A HISTORY OF AERONAUTICS by E. Charles Vivian FOREWORD Although successful heavier-than-air flight is less than two decadesold, and successful dirigible propulsion antedates it by a very shortperiod, the mass of experiment and accomplishment renders any one-volumehistory of the subject a matter of selection. In addition to therestrictions imposed by space limits, the material for compilation isfragmentary, and, in many cases, scattered through periodical andother publications. Hitherto, there has been no attempt at furnishing adetailed account of how the aeroplane and the dirigible of to-day cameto being, but each author who has treated the subject has devoted hisattention to some special phase or section. The principal exception tothis rule--Hildebrandt--wrote in 1906, and a good many of his statementsare inaccurate, especially with regard to heavier-than-air experiment. Such statements as are made in this work are, where possible, givenwith acknowledgment to the authorities on which they rest. Furtheracknowledgment is due to Lieut. -Col. Lockwood Marsh, not only for thesection on aeroplane development which he has contributed to the work, but also for his kindly assistance and advice in connection with thesection on aerostation. The author's thanks are also due to theRoyal Aeronautical Society for free access to its valuable library ofaeronautical literature, and to Mr A. Vincent Clarke for permission tomake use of his notes on the development of the aero engine. In this work is no claim to originality--it has been a matter mainly ofcompilation, and some stories, notably those of the Wright Brothers andof Santos Dumont, are better told in the words of the men themselvesthan any third party could tell them. The author claims, however, thatthis is the first attempt at recording the facts of development andstating, as fully as is possible in the compass of a single volume, howflight and aerostation have evolved. The time for a critical history ofthe subject is not yet. In the matter of illustrations, it has been found very difficult tosecure suitable material. Even the official series of photographs ofaeroplanes in the war period is curiously incomplete' and the methodsof censorship during that period prevented any complete series beingprivately collected. Omissions in this respect will probably be remediedin future editions of the work, as fresh material is constantly beinglocated. E. C. V. October, 1920. CONTENTS Part I--THE EVOLUTION OF THE AEROPLANE I. THE PERIOD OF LEGEND II. EARLY EXPERIMENTS III. SIR GEORGE CAYLEY--THOMAS WALKER IV. THE MIDDLE NINETEENTH CENTURY V. WENHAM, LE BRIS, AND SOME OTHERS VI. THE AGE OF THE GIANTS VII. LILIENTHAL AND PILCHER VIII. AMERICAN GLIDING EXPERIMENTS IX. NOT PROVEN X. SAMUEL PIERPOINT LANGLEY XI. THE WRIGHT BROTHERS XII. THE FIRST YEARS OF CONQUEST XIII. FIRST FLIERS IN ENGLAND XIV. RHEIMS, AND AFTER XV. THE CHANNEL CROSSING XVI. LONDON TO MANCHESTER XVII. A SUMMARY--TO 1911 XVIII. A SUMMARY--TO 1914 XIX. THE WAR PERIOD--I XX. THE WAR PERIOD--II XXI. RECONSTRUCTION XXII. 1919-1920 Part II--1903-1920: PROGRESS IN DESIGN I. THE BEGINNINGS II. MULTIPLICITY OF IDEAS III. PROGRESS ON STANDARDISED LINES IV. THE WAR PERIOD Part III--AEROSTATICS I. BEGINNINGS II. THE FIRST DIRIGIBLES III. SANTOS-DUMONT IV. THE MILITARY DIRIGIBLE V. BRITISH AIRSHIP DESIGN VI. THE AIRSHIP COMMERCIALLY VII. KITE BALLOONS PART IV--ENGINE DEVELOPMENT I. THE VERTICAL TYPE II. THE VEE TYPE III. THE RADIAL TYPE IV. THE ROTARY TYPE V. THE HORIZONTALLY-OPPOSED ENGINE VI. THE TWO-STROKE CYCLE ENGINE VII. ENGINES OF THE WAR PERIOD APPENDICES PART I. THE EVOLUTION OF THE AEROPLANE I. THE PERIOD OF LEGEND The blending of fact and fancy which men call legend reached its fullestand richest expression in the golden age of Greece, and thus it is toGreek mythology that one must turn for the best form of any legend whichforeshadows history. Yet the prevalence of legends regarding flight, existing in the records of practically every race, shows that this formof transit was a dream of many peoples--man always wanted to fly, andimagined means of flight. In this age of steel, a very great part of the inventive genius of manhas gone into devices intended to facilitate transport, both of men andgoods, and the growth of civilisation is in reality the facilitation oftransit, improvement of the means of communication. He was a genius whofirst hoisted a sail on a boat and saved the labour of rowing; equally, he who first harnessed ox or dog or horse to a wheeled vehicle was agenius--and these looked up, as men have looked up from the earliestdays of all, seeing that the birds had solved the problem of transit farmore completely than themselves. So it must have appeared, and thereis no age in history in which some dreamers have not dreamed of theconquest of the air; if the caveman had left records, these wouldwithout doubt have showed that he, too, dreamed this dream. His mainaim, probably, was self-preservation; when the dinosaur looked round thecorner, the prehistoric bird got out of the way in his usual manner, and prehistoric man, such of him as succeeded in getting out of the wayafter his fashion--naturally envied the bird, and concluded that as lordof creation in a doubtful sort of way he ought to have equalfacilities. He may have tried, like Simon the Magician, and other earlyexperimenters, to improvise those facilities; assuming that he did, there is the groundwork of much of the older legend with regard to menwho flew, since, when history began, legends would be fashioned outof attempts and even the desire to fly, these being compounded of somesmall ingredient of truth and much exaggeration and addition. In a study of the first beginnings of the art, it is worth while tomention even the earliest of the legends and traditions, for they showthe trend of men's minds and the constancy of this dream that has becomereality in the twentieth century. In one of the oldest records of theworld, the Indian classic Mahabarata, it is stated that 'Krishna'senemies sought the aid of the demons, who built an aerial chariot withsides of iron and clad with wings. The chariot was driven through thesky till it stood over Dwarakha, where Krishna's followers dwelt, and from there it hurled down upon the city missiles that destroyedeverything on which they fell. ' Here is pure fable, not legend, butstill a curious forecast of twentieth century bombs from a rigiddirigible. It is to be noted in this case, as in many, that the power tofly was an attribute of evil, not of good--it was the demons who builtthe chariot, even as at Friedrichshavn. Mediaeval legend in nearlyevery case, attributes flight to the aid of evil powers, and inciteswell-disposed people to stick to the solid earth--though, curiouslyenough, the pioneers of medieval times were very largely of priestlytype, as witness the monk of Malmesbury. The legends of the dawn of history, however, distribute the power offlight with less of prejudice. Egyptian sculpture gives the figureof winged men; the British Museum has made the winged Assyrian bullsfamiliar to many, and both the cuneiform records of Assyria and thehieroglyphs of Egypt record flights that in reality were never made. The desire fathered the story then, and until Clement Ader either hoppedwith his Avion, as is persisted by his critics, or flew, as is claimedby his friends. While the origin of many legends is questionable, that of others iseasy enough to trace, though not to prove. Among the credulous thesignificance of the name of a people of Asia Minor, the Capnobates, 'those who travel by smoke, ' gave rise to the assertion that Montgolfierwas not first in the field--or rather in the air--since surely thispeople must have been responsible for the first hot-air balloons. Farless questionable is the legend of Icarus, for here it is possibleto trace a foundation of fact in the story. Such a tribe as Daedalusgoverned could have had hardly any knowledge of the rudiments ofscience, and even their ruler, seeing how easy it is for birds tosustain themselves in the air, might be excused for believing that he, if he fashioned wings for himself, could use them. In that belief, letit be assumed, Daedalus made his wings; the boy, Icarus, learning thathis father had determined on an attempt at flight secured the wings andfastened them to his own shoulders. A cliff seemed the likeliest placefor a 'take-off, ' and Icarus leaped from the cliff edge only to findthat the possession of wings was not enough to assure flight to a humanbeing. The sea that to this day bears his name witnesses that he madethe attempt and perished by it. In this is assumed the bald story, from which might grow the legend of awise king who ruled a peaceful people--'judged, sitting in the sun, ' asBrowning has it, and fashioned for himself wings with which he flew overthe sea and where he would, until the prince, Icarus, desired to emulatehim. Icarus, fastening the wings to his shoulders with wax, was soimprudent as to fly too near the sun, when the wax melted and he fell, to lie mourned of water-nymphs on the shores of waters thenceforthIcarian. Between what we have assumed to be the base of fact, and thelegend which has been invested with such poetic grace in Greek story, there is no more than a century or so of re-telling might give to anyevent among a people so simple and yet so given to imagery. We may set aside as pure fable the stories of the winged horse ofPerseus, and the flights of Hermes as messenger of the gods. With themmay be placed the story of Empedocles, who failed to take Etna seriouslyenough, and found himself caught by an eruption while within the crater, so that, flying to safety in some hurry, he left behind but one sandalto attest that he had sought refuge in space--in all probability, ifhe escaped at all, he flew, but not in the sense that the aeronautunderstands it. But, bearing in mind the many men who tried to flyin historic times, the legend of Icarus and Daedalus, in spite of theimpossible form in which it is presented, may rank with the story of theSaracen of Constantinople, or with that of Simon the Magician. A simplefolk would naturally idealise the man and magnify his exploit, as theymagnified the deeds of some strong man to make the legends of Hercules, and there, full-grown from a mere legend, is the first record of apioneer of flying. Such a theory is not nearly so fantastic as thatwhich makes the Capnobates, on the strength of their name, the inventorsof hot-air balloons. However it may be, both in story and in picture, Icarus and his less conspicuous father have inspired the Caucasian mind, and the world is the richer for them. Of the unsupported myths--unsupported, that is, by even a shadow ofprobability--there is no end. Although Latin legend approaches nearerto fact than the Greek in some cases, in others it shows a disregardfor possibilities which renders it of far less account. Thus Diodorus ofSicily relates that one Abaris travelled round the world on an arrow ofgold, and Cassiodorus and Glycas and their like told of mechanical birdsthat flew and sang and even laid eggs. More credible is the storyof Aulus Gellius, who in his Attic Nights tells how Archytas, fourcenturies prior to the opening of the Christian era, made a woodenpigeon that actually flew by means of a mechanism of balancing weightsand the breath of a mysterious spirit hidden within it. There may yetarise one credulous enough to state that the mysterious spirit wasprecursor of the internal combustion engine, but, however that may be, the pigeon of Archytas almost certainly existed, and perhaps it actuallyglided or flew for short distances--or else Aulus Gellius was an utterliar, like Cassiodorus and his fellows. In far later times a certainJohn Muller, better known as Regiomontanus, is stated to have made anartificial eagle which accompanied Charles V. On his entry to and exitfrom Nuremberg, flying above the royal procession. But, since Mullerdied in 1436 and Charles was born in 1500, Muller may be ruled out fromamong the pioneers of mechanical flight, and it may be concluded thatthe historian of this event got slightly mixed in his dates. Thus far, we have but indicated how one may draw from the richeststores from which the Aryan mind draws inspiration, the Greek and Latinmythologies and poetic adaptations of history. The existing legends offlight, however, are not thus to be localised, for with two possibleexceptions they belong to all the world and to every civilisation, however primitive. The two exceptions are the Aztec and the Chinese;regarding the first of these, the Spanish conquistadores destroyed suchcivilisation as existed in Tenochtitlan so thoroughly that, if legendof flight was among the Aztec records, it went with the rest; as to theChinese, it is more than passing strange that they, who claim to haveknown and done everything while the first of history was shaping, evento antedating the discovery of gunpowder that was not made by RogerBacon, have not yet set up a claim to successful handling of a monoplanesome four thousand years ago, or at least to the patrol of the Gulf ofKorea and the Mongolian frontier by a forerunner of the 'blimp. ' The Inca civilisation of Peru yields up a myth akin to that of Icarus, which tells how the chieftain Ayar Utso grew wings and visited thesun--it was from the sun, too, that the founders of the Peruvian Incadynasty, Manco Capac and his wife Mama Huella Capac, flew to earth nearLake Titicaca, to make the only successful experiment in pure tyrannythat the world has ever witnessed. Teutonic legend gives forth Wielandthe Smith, who made himself a dress with wings and, clad in it, roseand descended against the wind and in spite of it. Indian mythology, inaddition to the story of the demons and their rigid dirigible, alreadyquoted, gives the story of Hanouam, who fitted himself with wings bymeans of which he sailed in the air and, according to his desire, landedin the sacred Lauka. Bladud, the ninth king of Britain, is said to havecrowned his feats of wizardry by making himself wings and attemptingto fly--but the effort cost him a broken neck. Bladud may have been asmythic as Uther, and again he may have been a very early pioneer. TheFinnish epic, 'Kalevala, ' tells how Ilmarinen the Smith 'forged an eagleof fire, ' with 'boat's walls between the wings, ' after which he 'satdown on the bird's back and bones, ' and flew. Pure myths, these, telling how the desire to fly was characteristic ofevery age and every people, and how, from time to time, there arose anexperimenter bolder than his fellows, who made some attempt to translatedesire into achievement. And the spirit that animated these pioneers, in a time when things new were accounted things accursed, for the mostpart, has found expression in this present century in the utter daringand disregard of both danger and pain that stamps the flying man, a typeof humanity differing in spirit from his earthbound fellows as fully asthe soldier differs from the priest. Throughout mediaeval times, records attest that here and there some manbelieved in and attempted flight, and at the same time it is clear thatsuch were regarded as in league with the powers of evil. There is thehalf-legend, half-history of Simon the Magician, who, in the third yearof the reign of Nero announced that he would raise himself in the air, in order to assert his superiority over St Paul. The legend states thatby the aid of certain demons whom he had prevailed on to assist him, heactually lifted himself in the air--but St Paul prayed him down again. He slipped through the claws of the demons and fell headlong on theForum at Rome, breaking his neck. The 'demons' may have been someprimitive form of hot-air balloon, or a glider with which the magicianattempted to rise into the wind; more probably, however, Simonthreatened to ascend and made the attempt with apparatus as unsuitableas Bladud's wings, paying the inevitable penalty. Another version of thestory gives St Peter instead of St Paul as the one whose prayers foiledSimon--apart from the identity of the apostle, the two accounts aresimilar, and both define the attitude of the age toward investigationand experiment in things untried. Another and later circumstantial story, with similar evidence of somefact behind it, is that of the Saracen of Constantinople, who, in thereign of the Emperor Comnenus--some little time before Norman Williammade Saxon Harold swear away his crown on the bones of the saints atRouen--attempted to fly round the hippodrome at Constantinople, havingComnenus among the great throng who gathered to witness the feat. The Saracen chose for his starting-point a tower in the midst of thehippodrome, and on the top of the tower he stood, clad in a long whiterobe which was stiffened with rods so as to spread and catch the breeze, waiting for a favourable wind to strike on him. The wind was so long incoming that the spectators grew impatient. 'Fly, O Saracen!' theycalled to him. 'Do not keep us waiting so long while you try the wind!'Comnenus, who had present with him the Sultan of the Turks, gave itas his opinion that the experiment was both dangerous and vain, and, possibly in an attempt to controvert such statement, the Saracen leanedinto the wind and 'rose like a bird 'at the outset. But the record ofCousin, who tells the story in his Histoire de Constantinople, statesthat 'the weight of his body having more power to drag him down than hisartificial wings had to sustain him, he broke his bones, and his evilplight was such that he did not long survive. ' Obviously, the Saracen was anticipating Lilienthal and his gliders bysome centuries; like Simon, a genuine experimenter--both legendsbear the impress of fact supporting them. Contemporary with him, andbelonging to the history rather than the legends of flight, was Oliver, the monk of Malmesbury, who in the year 1065 made himself wings afterthe pattern of those supposed to have been used by Daedalus, attachingthem to his hands and feet and attempting to fly with them. Twysden, inhis Historiae Anglicanae Scriptores X, sets forth the story of Oliver, who chose a high tower as his starting-point, and launched himself inthe air. As a matter of course, he fell, permanently injuring himself, and died some time later. After these, a gap of centuries, filled in by impossible stories ofmagical flight by witches, wizards, and the like--imagination wasfertile in the dark ages, but the ban of the church was on all attemptat scientific development, especially in such a matter as the conquestof the air. Yet there were observers of nature who argued that sincebirds could raise themselves by flapping their wings, man had only tomake suitable wings, flap them, and he too would fly. As early asthe thirteenth century Roger Bacon, the scientific friar of unboundedinquisitiveness and not a little real genius, announced that there couldbe made 'some flying instrument, so that a man sitting in the middle andturning some mechanism may put in motion some artificial wings whichmay beat the air like a bird flying. ' But being a cautious man, with anatural dislike for being burnt at the stake as a necromancer throughhaving put forward such a dangerous theory, Roger added, 'not thatI ever knew a man who had such an instrument, but I am particularlyacquainted with the man who contrived one. ' This might have been a lamedefence if Roger had been brought to trial as addicted to black arts; heseems to have trusted to the inadmissibility of hearsay evidence. Some four centuries later there was published a book entitled PerugiaAugusta, written by one C. Crispolti of Perugia--the date of the work inquestion is 1648. In it is recorded that 'one day, towards the close ofthe fifteenth century, whilst many of the principal gentry had cometo Perugia to honour the wedding of Giovanni Paolo Baglioni, and somelancers were riding down the street by his palace, Giovanni BaptistiDanti unexpectedly and by means of a contrivance of wings that he hadconstructed proportionate to the size of his body took off from the topof a tower near by, and with a horrible hissing sound flew successfullyacross the great Piazza, which was densely crowded. But (oh, horror ofan unexpected accident!) he had scarcely flown three hundred paces onhis way to a certain point when the mainstay of the left wing gave way, and, being unable to support himself with the right alone, he fell on aroof and was injured in consequence. Those who saw not only this flight, but also the wonderful construction of the framework of the wings, said--and tradition bears them out--that he several times flew over thewaters of Lake Thrasimene to learn how he might gradually come to earth. But, notwithstanding his great genius, he never succeeded. ' This reads circumstantially enough, but it may be borne in mind that thedate of writing is more than half a century later than the time of thealleged achievement--the story had had time to round itself out. Danti, however, is mentioned by a number of writers, one of whom states thatthe failure of his experiment was due to the prayers of some individualof a conservative turn of mind, who prayed so vigorously that Danti fellappropriately enough on a church and injured himself to such an extentas to put an end to his flying career. That Danti experimented, thereis little doubt, in view of the volume of evidence on the point, but thedarkness of the Middle Ages hides the real truth as to the results ofhis experiments. If he had actually flown over Thrasimene, as alleged, then in all probability both Napoleon and Wellington would have had airscouts at Waterloo. Danti's story may be taken as fact or left as fable, and with it theperiod of legend or vague statement may be said to end--the rest ishistory, both of genuine experimenters and of charlatans. Such instancesof legend as are given here are not a tithe of the whole, but there issufficient in the actual history of flight to bar out more than thisbrief mention of the legends, which, on the whole, go farther to proveman's desire to fly than his study and endeavour to solve the problemsof the air. II. EARLY EXPERIMENTS So far, the stories of the development of flight are either legendaryor of more or less doubtful authenticity, even including that of Danti, who, although a man of remarkable attainments in more directionsthan that of attempted flight, suffers--so far as reputation isconcerned--from the inexactitudes of his chroniclers; he may have soaredover Thrasimene, as stated, or a mere hop with an ineffectual glider mayhave grown with the years to a legend of gliding flight. So far, too, there is no evidence of the study that the conquest of the air demanded;such men as made experiments either launched themselves in the air fromsome height with made-up wings or other apparatus, and paid the penalty, or else constructed some form of machine which would not leave theearth, and then gave up. Each man followed his own way, and there was noattempt--without the printing press and the dissemination of knowledgethere was little possibility of attempt--on the part of any one tobenefit by the failures of others. Legend and doubtful history carries up to the fifteenth century, andthen came Leonardo da Vinci, first student of flight whose work enduresto the present day. The world knows da Vinci as artist; his age knew himas architect, engineer, artist, and scientist in an age when science wasa single study, comprising all knowledge from mathematics to medicine. He was, of course, in league with the devil, for in no other waycould his range of knowledge and observation be explained by hiscontemporaries; he left a Treatise on the Flight of Birds in which arestatements and deductions that had to be rediscovered when the Treatisehad been forgotten--da Vinci anticipated modern knowledge as Platoanticipated modern thought, and blazed the first broad trail towardflight. One Cuperus, who wrote a Treatise on the Excellence of Man, assertedthat da Vinci translated his theories into practice, and actually flew, but the statement is unsupported. That he made models, especially onthe helicopter principle, is past question; these were made of paper andwire, and actuated by springs of steel wire, which caused them to liftthemselves in the air. It is, however, in the theories which he putforward that da Vinci's investigations are of greatest interest; theseprove him a patient as well as a keen student of the principles offlight, and show that his manifold activities did not prevent him fromdevoting some lengthy periods to observations of bird flight. 'A bird, ' he says in his Treatise, 'is an instrument working accordingto mathematical law, which instrument it is within the capacity of manto reproduce with all its movements, but not with a correspondingdegree of strength, though it is deficient only in power of maintainingequilibrium. We may say, therefore, that such an instrument constructedby man is lacking in nothing except the life of the bird, and this lifemust needs be supplied from that of man. The life which resides in thebird's members will, without doubt, better conform to their needs thanwill that of a man which is separated from them, and especially in thealmost imperceptible movements which produce equilibrium. But since wesee that the bird is equipped for many apparent varieties of movement, we are able from this experience to deduce that the most rudimentaryof these movements will be capable of being comprehended by man'sunderstanding, and that he will to a great extent be able to provideagainst the destruction of that instrument of which he himself hasbecome the living principle and the propeller. ' In this is the definite belief of da Vinci that man is capable offlight, together with a far more definite statement of the principles bywhich flight is to be achieved than any which had preceded it--and forthat matter, than many that have succeeded it. Two further extracts fromhis work will show the exactness of his observations:-- 'When a bird which is in equilibrium throws the centre of resistance ofthe wings behind the centre of gravity, then such a bird will descendwith its head downward. This bird which finds itself in equilibriumshall have the centre of resistance of the wings more forward thanthe bird's centre of gravity; then such a bird will fall with its tailturned toward the earth. ' And again: 'A man, when flying, shall be free from the waist up, that hemay be able to keep himself in equilibrium as he does in a boat, sothat the centre of his gravity and of the instrument may set itself inequilibrium and change when necessity requires it to the changing of thecentre of its resistance. ' Here, in this last quotation, are the first beginnings of the inherentstability which proved so great an advance in design, in this twentiethcentury. But the extracts given do not begin to exhaust the range ofda Vinci's observations and deductions. With regard to bird flight, heobserved that so long as a bird keeps its wings outspread it cannot falldirectly to earth, but must glide down at an angle to alight--a smallthing, now that the principle of the plane in opposition to the air isgenerally grasped, but da Vinci had to find it out. From observationhe gathered how a bird checks its own speed by opposing tail and wingsurface to the direction of flight, and thus alights at the proper'landing speed. ' He proved the existence of upward air currents bynoting how a bird takes off from level earth with wings outstretched andmotionless, and, in order to get an efficient substitute for thenatural wing, he recommended that there be used something similar tothe membrane of the wing of a bat--from this to the doped fabric of anaeroplane wing is but a small step, for both are equally impervious toair. Again, da Vinci recommended that experiments in flight be conductedat a good height from the ground, since, if equilibrium be lost throughany cause, the height gives time to regain it. This recommendation, bythe way, received ample support in the training areas of war pilots. Man's muscles, said da Vinci, are fully sufficient to enable him tofly, for the larger birds, he noted, employ but a small part of theirstrength in keeping themselves afloat in the air--by this theory heattempted to encourage experiment, just as, when his time came, Borellireached the opposite conclusion and discouraged it. That Borelli wasright--so far--and da Vinci wrong, detracts not at all from the reputeof the earlier investigator, who had but the resources of his age tosupport investigations conducted in the spirit of ages after. His chief practical contributions to the science of flight--apartfrom numerous drawings which have still a value--are the helicopter orlifting screw, and the parachute. The former, as already noted, hemade and proved effective in model form, and the principle which hedemonstrated is that of the helicopter of to-day, on which sundryexperimenters work spasmodically, in spite of the success of the planewith its driving propeller. As to the parachute, the idea was doubtlessinspired by observation of the effect a bird produced by pressure of itswings against the direction of flight. Da Vinci's conclusions, and his experiments, were forgotten easily bymost of his contemporaries; his Treatise lay forgotten for nearly fourcenturies, overshadowed, mayhap, by his other work. There was, however, a certain Paolo Guidotti of Lucca, who lived in the latter half of thesixteenth century, and who attempted to carry da Vinci's theories--oneof them, at least, into practice. For this Guidotti, who was byprofession an artist and by inclination an investigator, made forhimself wings, of which the framework was of whalebone; these he coveredwith feathers, and with them made a number of gliding flights, attainingconsiderable proficiency. He is said in the end to have made a flight ofabout four hundred yards, but this attempt at solving the problemended on a house roof, where Guidotti broke his thigh bone. After that, apparently, he gave up the idea of flight, and went back to painting. One other a Venetian architect named Veranzio, studied da Vinci's theoryof the parachute, and found it correct, if contemporary records and evenpictorial presentment are correct. Da Vinci showed his conception of aparachute as a sort of inverted square bag; Veranzio modified this to a'sort of square sail extended by four rods of equal size and having fourcords attached at the corners, ' by means of which 'a man could withoutdanger throw himself from the top of a tower or any high place. Forthough at the moment there may be no wind, yet the effort of his fallingwill carry up the wind, which the sail will hold, by which means he doesnot fall suddenly but descends little by little. The size of the sailshould be measured to the man. ' By this last, evidently, Veranziointended to convey that the sheet must be of such content as wouldenclose sufficient air to support the weight of the parachutist. Veranzio made his experiments about 1617-1618, but, naturally, theycarried him no farther than the mere descent to earth, and since adescent is merely a descent, it is to be conjectured that he soon gottired of dropping from high roofs, and took to designing architectureinstead of putting it to such a use. With the end of his experiments thework of da Vinci in relation to flying became neglected for nearly fourcenturies. Apart from these two experimenters, there is little to record in thematter either of experiment or study until the seventeenth century. Francis Bacon, it is true, wrote about flying in his Sylva Sylvarum, andmentioned the subject in the New Atlantis, but, except for the insightthat he showed even in superficial mention of any specific subject, he does not appear to have made attempt at serious investigation. 'Spreading of Feathers, thin and close and in great breadth willlikewise bear up a great Weight, ' says Francis, 'being even laid withoutTilting upon the sides. ' But a lesser genius could have told as much, even in that age, and though the great Sir Francis is sometimes adducedas one of the early students of the problems of flight, his writingswill not sustain the reputation. The seventeenth century, however, gives us three names, those ofBorelli, Lana, and Robert Hooke, all of which take definite place inthe history of flight. Borelli ranks as one of the great figures in thestudy of aeronautical problems, in spite of erroneous deductions throughwhich he arrived at a purely negative conclusion with regard to thepossibility of human flight. Borelli was a versatile genius. Born in 1608, he was practicallycontemporary with Francesco Lana, and there is evidence that he eitherknew or was in correspondence with many prominent members of the RoyalSociety of Great Britain, more especially with John Collins, Dr Wallis, and Henry Oldenburgh, the then Secretary of the Society. He was authorof a long list of scientific essays, two of which only are responsiblefor his fame, viz. , Theorice Medicaearum Planetarum, published inFlorence, and the better known posthumous De Motu Animalium. The firstof these two is an astronomical study in which Borelli gives evidence ofan instinctive knowledge of gravitation, though no definite expressionis given of this. The second work, De Motu Animalium, deals with themechanical action of the limbs of birds and animals and with a theory ofthe action of the internal organs. A section of the first part ofthis work, called De Volatu, is a study of bird flight; it is quiteindependent of Da Vinci's earlier work, which had been forgotten andremained unnoticed until near on the beginning of practical flight. Marey, in his work, La Machine Animale, credits Borelli with the firstcorrect idea of the mechanism of flight. He says: 'Therefore we must beallowed to render to the genius of Borelli the justice which is dueto him, and only claim for ourselves the merit of having furnished theexperimental demonstration of a truth already suspected. ' In fact, allsubsequent studies on this subject concur in making Borelli the firstinvestigator who illustrated the purely mechanical theory of the actionof a bird's wings. Borelli's study is divided into a series of propositions in which hetraces the principles of flight, and the mechanical actions of the wingsof birds. The most interesting of these are the propositions in which hesets forth the method in which birds move their wings during flight andthe manner in which the air offers resistance to the stroke of the wing. With regard to the first of these two points he says: 'When birds inrepose rest on the earth their wings are folded up close against theirflanks, but when wishing to start on their flight they first bend theirlegs and leap into the air. Whereupon the joints of their wings arestraightened out to form a straight line at right angles to the lateralsurface of the breast, so that the two wings, outstretched, are placed, as it were, like the arms of a cross to the body of the bird. Next, since the wings with their feathers attached form almost a planesurface, they are raised slightly above the horizontal, and with amost quick impulse beat down in a direction almost perpendicular to thewing-plane, upon the underlying air; and to so intense a beat the air, notwithstanding it to be fluid, offers resistance, partly by reasonof its natural inertia, which seeks to retain it at rest, and partlybecause the particles of the air, compressed by the swiftness of thestroke, resist this compression by their elasticity, just like the hardground. Hence the whole mass of the bird rebounds, making a freshleap through the air; whence it follows that flight is simply a motioncomposed of successive leaps accomplished through the air. And I remarkthat a wing can easily beat the air in a direction almost perpendicularto its plane surface, although only a single one of the corners of thehumerus bone is attached to the scapula, the whole extent of its baseremaining free and loose, while the greater transverse feathers arejoined to the lateral skin of the thorax. Nevertheless the wing caneasily revolve about its base like unto a fan. Nor are there lackingtendon ligaments which restrain the feathers and prevent them fromopening farther, in the same fashion that sheets hold in the sails ofships. No less admirable is nature's cunning in unfolding and foldingthe wings upwards, for she folds them not laterally, but by movingupwards edgewise the osseous parts wherein the roots of the feathers areinserted; for thus, without encountering the air's resistance the upwardmotion of the wing surface is made as with a sword, hence they can beuplifted with but small force. But thereafter when the wings are twistedby being drawn transversely and by the resistance of the air, they areflattened as has been declared and will be made manifest hereafter. ' Then with reference to the resistance to the air of the wings heexplains: 'The air when struck offers resistance by its elastic virtuethrough which the particles of the air compressed by the wing-beatstrive to expand again. Through these two causes of resistance thedownward beat of the wing is not only opposed, but even caused to recoilwith a reflex movement; and these two causes of resistance ever increasethe more the down stroke of the wing is maintained and accelerated. Onthe other hand, the impulse of the wing is continuously diminished andweakened by the growing resistance. Hereby the force of the wing and theresistance become balanced; so that, manifestly, the air is beaten bythe wing with the same force as the resistance to the stroke. ' He concerns himself also with the most difficult problem that confrontsthe flying man of to-day, namely, landing effectively, and his remarkson this subject would be instructive even to an air pilot of these days:'Now the ways and means by which the speed is slackened at the end ofa flight are these. The bird spreads its wings and tail so that theirconcave surfaces are perpendicular to the direction of motion; in thisway, the spreading feathers, like a ship's sail, strike against thestill air, check the speed, and so that most of the impetus may bestopped, the wings are flapped quickly and strongly forward, inducing acontrary motion, so that the bird absolutely or very nearly stops. ' At the end of his study Borelli came to a conclusion which militatedgreatly against experiment with any heavier-than-air apparatus, untilwell on into the nineteenth century, for having gone thoroughly into thesubject of bird flight he states distinctly in his last propositionon the subject that 'It is impossible that men should be able to flycraftily by their own strength. ' This statement, of course, remains trueup to the present day for no man has yet devised the means by which hecan raise himself in the air and maintain himself there by mere musculareffort. From the time of Borelli up to the development of the steam engine itmay be said that flight by means of any heavier-than-air apparatus wasgenerally regarded as impossible, and apart from certain deductionswhich a little experiment would have shown to be doomed to failure, thismethod of flight was not followed up. It is not to be wondered at, whenBorelli's exaggerated estimate of the strength expended by birds inproportion to their weight is borne in mind; he alleged that the motiveforce in birds' wings is 10, 000 times greater than the resistance oftheir weight, and with regard to human flight he remarks:-- 'When, therefore, it is asked whether men may be able to fly by theirown strength, it must be seen whether the motive power of the pectoralmuscles (the strength of which is indicated and measured by their size)is proportionately great, as it is evident that it must exceed theresistance of the weight of the whole human body 10, 000 times, togetherwith the weight of enormous wings which should be attached to the arms. And it is clear that the motive power of the pectoral muscles in men ismuch less than is necessary for flight, for in birds the bulk and weightof the muscles for flapping the wings are not less than a sixth part ofthe entire weight of the body. Therefore, it would be necessary thatthe pectoral muscles of a man should weigh more than a sixth part of theentire weight of his body; so also the arms, by flapping with the wingsattached, should be able to exert a power 10, 000 times greater than theweight of the human body itself. But they are far below such excess, for the aforesaid pectoral muscles do not equal a hundredth part of theentire weight of a man. Wherefore either the strength of the musclesought to be increased or the weight of the human body must be decreased, so that the same proportion obtains in it as exists in birds. Henceit is deducted that the Icarian invention is entirely mythical becauseimpossible, for it is not possible either to increase a man's pectoralmuscles or to diminish the weight of the human body; and whateverapparatus is used, although it is possible to increase the momentum, the velocity or the power employed can never equal the resistance; andtherefore wing flapping by the contraction of muscles cannot give outenough power to carry up the heavy body of a man. ' It may be said that practically all the conclusions which Borellireached in his study were negative. Although contemporary with Lana, he perceived the one factor which rendered Lana's project for flight bymeans of vacuum globes an impossibility--he saw that no globe couldbe constructed sufficiently light for flight, and at the same timesufficiently strong to withstand the pressure of the outside atmosphere. He does not appear to have made any experiments in flying on hisown account, having, as he asserts most definitely, no faith in anyinvention designed to lift man from the surface of the earth. But hiswork, from which only the foregoing short quotations can be given, is, nevertheless, of indisputable value, for he settled the mechanics ofbird flight, and paved the way for those later investigators who had, first, the steam engine, and later the internal combustion engine--twofactors in mechanical flight which would have seemed as impossible toBorelli as would wireless telegraphy to a student of Napoleonic times. On such foundations as his age afforded Borelli built solidly andwell, so that he ranks as one of the greatest--if not actually thegreatest--of the investigators into this subject before the age ofsteam. The conclusion, that 'the motive force in birds' wings is apparentlyten thousand times greater than the resistance of their weight, ' iserroneous, of course, but study of the translation from which theforegoing excerpt is taken will show that the error detracts very littlefrom the value of the work itself. Borelli sets out very definitelythe mechanism of flight, in such fashion that he who runs may read. Hisreference to 'the use of a large vessel, ' etc. , concerns the suggestionmade by Francesco Lana, who antedated Borelli's publication of De MotuAnimalium by some ten years with his suggestion for an 'aerial ship, ' ashe called it. Lana's mind shows, as regards flight, a more imaginativetwist; Borelli dived down into first causes, and reached mathematicalconclusions; Lana conceived a theory and upheld it--theoretically, sincethe manner of his life precluded experiment. Francesco Lana, son of a noble family, was born in 1631; in 1647 he wasreceived as a novice into the Society of Jesus at Rome, and remaineda pious member of the Jesuit society until the end of his life. He wasgreatly handicapped in his scientific investigations by the vowsof poverty which the rules of the Order imposed on him. He was morescientist than priest all his life; for two years he held the post ofProfessor of Mathematics at Ferrara, and up to the time of his death, in 1687, he spent by far the greater part of his time in scientificresearch, He had the dubious advantage of living in an age when one mancould cover the whole range of science, and this he seems to havedone very thoroughly. There survives an immense work of his entitled, Magisterium Naturae et Artis, which embraces the whole field ofscientific knowledge as that was developed in the period in which Lanalived. In an earlier work of his, published in Brescia in 1670, appearshis famous treatise on the aerial ship, a problem which Lana worked outwith thoroughness. He was unable to make practical experiments, and thusfailed to perceive the one insuperable drawback to his project--of whichmore anon. Only extracts from the translation of Lana's work can be given here, butsufficient can be given to show fully the means by which he designed toachieve the conquest of the air. He begins by mention of the celebratedpigeon of Archytas the Philosopher, and advances one or two theorieswith regard to the way in which this mechanical bird was constructed, and then he recites, apparently with full belief in it, the fable ofRegiomontanus and the eagle that he is said to have constructed toaccompany Charles V. On his entry into Nuremberg. In fact, Lana startshis work with a study of the pioneers of mechanical flying up to hisown time, and then outlines his own devices for the construction ofmechanical birds before proceeding to detail the construction of theaerial ship. Concerning primary experiments for this he says:-- 'I will, first of all, presuppose that air has weight owing to thevapours and halations which ascend from the earth and seas to a heightof many miles and surround the whole of our terraqueous globe; and thisfact will not be denied by philosophers, even by those who may have buta superficial knowledge, because it can be proven by exhausting, ifnot all, at any rate the greater part of, the air contained in a glassvessel, which, if weighed before and after the air has been exhausted, will be found materially reduced in weight. Then I found out how muchthe air weighed in itself in the following manner. I procured a largevessel of glass, whose neck could be closed or opened by means of a tap, and holding it open I warmed it over a fire, so that the air inside itbecoming rarified, the major part was forced out; then quickly shuttingthe tap to prevent the re-entry I weighed it; which done, I plunged itsneck in water, resting the whole of the vessel on the surface of thewater, then on opening the tap the water rose in the vessel and filledthe greater part of it. I lifted the neck out of the water, released thewater contained in the vessel, and measured and weighed its quantity anddensity, by which I inferred that a certain quantity of air had come outof the vessel equal in bulk to the quantity of water which had enteredto refill the portion abandoned by the air. I again weighed the vessel, after I had first of all well dried it free of all moisture, and foundit weighed one ounce more whilst it was full of air than when it wasexhausted of the greater part, so that what it weighed more was aquantity of air equal in volume to the water which took its place. Thewater weighed 640 ounces, so I concluded that the weight of air comparedwith that of water was 1 to 640--that is to say, as the water whichfilled the vessel weighed 640 ounces, so the air which filled the samevessel weighed one ounce. ' Having thus detailed the method of exhausting air from a vessel, Lanagoes on to assume that any large vessel can be entirely exhausted ofnearly all the air contained therein. Then he takes Euclid's propositionto the effect that the superficial area of globes increases in theproportion of the square of the diameter, whilst the volume increases inthe proportion of the cube of the same diameter, and he considers thatif one only constructs the globe of thin metal, of sufficient size, andexhausts the air in the manner that he suggests, such a globe will be sofar lighter than the surrounding atmosphere that it will not onlyrise, but will be capable of lifting weights. Here is Lana's own way ofputting it:-- 'But so that it may be enabled to raise heavier weights and to liftmen in the air, let us take double the quantity of copper, 1, 232 squarefeet, equal to 308 lbs. Of copper; with this double quantity of copperwe could construct a vessel of not only double the capacity, but offour times the capacity of the first, for the reason shown by my fourthsupposition. Consequently the air contained in such a vessel will be 718lbs. 4 2/3 ounces, so that if the air be drawn out of the vessel itwill be 410 lbs. 4 2/3 ounces lighter than the same volume of air, and, consequently, will be enabled to lift three men, or at least two, shouldthey weigh more than eight pesi each. It is thus manifest that thelarger the ball or vessel is made, the thicker and more solid can thesheets of copper be made, because, although the weight will increase, the capacity of the vessel will increase to a greater extent and with itthe weight of the air therein, so that it will always be capable to lifta heavier weight. From this it can be easily seen how it is possible toconstruct a machine which, fashioned like unto a ship, will float on theair. ' With four globes of these dimensions Lana proposed to make an aerialship of the fashion shown in his quaint illustration. He is careful topoint out a method by which the supporting globes for the aerial shipmay be entirely emptied of air; (this is to be done by connecting to eachglobe a tube of copper which is 'at least a length of 47 modern Romanpalm). ' A small tap is to close this tube at the end nearest the globe, and then vessel and tube are to be filled with water, after which thetube is to be immersed in water and the tap opened, allowing the waterto run out of the vessel, while no air enters. The tap is then closedbefore the lower end of the tube is removed from the water, leaving noair at all in the globe or sphere. Propulsion of this airship was to beaccomplished by means of sails, and also by oars. Lana antedated the modern propeller, and realised that the air wouldoffer enough resistance to oars or paddle to impart motion to any vesselfloating in it and propelled by these means, although he did not realisethe amount of pressure on the air which would be necessary to accomplishpropulsion. As a matter of fact, he foresaw and provided againstpractically all the difficulties that would be encountered in theworking, as well as the making, of the aerial ship, finally coming upagainst what his religious training made an insuperable objection. This, again, is best told in his own words:-- 'Other difficulties I do not foresee that could prevail against thisinvention, save one only, which to me seems the greatest of them all, and that is that God would surely never allow such a machine to besuccessful, since it would create many disturbances in the civil andpolitical governments of mankind. ' He ends by saying that no city would be proof against surprise, whilethe aerial ship could set fire to vessels at sea, and destroy houses, fortresses, and cities by fire balls and bombs. In fact, at the end ofhis treatise on the subject, he furnishes a pretty complete resume ofthe activities of German Zeppelins. As already noted, Lana himself, owing to his vows of poverty, wasunable to do more than put his suggestions on paper, which he did witha thoroughness that has procured him a place among the really greatpioneers of flying. It was nearly 200 years before any attempt was made to realise hisproject; then, in 1843, M. Marey Monge set out to make the globes andthe ship as Lana detailed them. Monge's experiments cost him the sumof 25, 000 francs 75 centimes, which he expended purely from loveof scientific investigation. He chose to make his globes of brass, about. 004 in thickness, and weighing 1. 465 lbs. To the square yard. Having made his sphere of this metal, he lined it with two thicknessesof tissue paper, varnished it with oil, and set to work to empty it ofair. This, however, he never achieved, for such metal is incapable ofsustaining the pressure of the outside air, as Lana, had he had themeans to carry out experiments, would have ascertained. M. Monge'ssphere could never be emptied of air sufficiently to rise from theearth; it ended in the melting-pot, ignominiously enough, and all thatMonge got from his experiment was the value of the scrap metal and thesatisfaction of knowing that Lana's theory could never be translatedinto practice. Robert Hooke is less conspicuous than either Borelli or Lana; his work, which came into the middle of the seventeenth century, consisted ofvarious experiments with regard to flight, from which emerged 'a Module, which by the help of Springs and Wings, raised and sustained itself inthe air. ' This must be reckoned as the first model flying machine whichactually flew, except for da Vinci's helicopters; Hooke's model appearsto have been of the flapping-wing type--he attempted to copy the motionof birds, but found from study and experiment that human muscles werenot sufficient to the task of lifting the human body. For that reason, he says, 'I applied my mind to contrive a way to make artificialmuscles, ' but in this he was, as he expresses it, 'frustrated of myexpectations. ' Hooke's claim to fame rests mainly on his successfulmodel; the rest of his work is of too scrappy a nature to rank as aserious contribution to the study of flight. Contemporary with Hooke was one Allard, who, in France, undertook toemulate the Saracen of Constantinople to a certain extent. Allard was atight-rope dancer who either did or was said to have done short glidingflights--the matter is open to question--and finally stated that hewould, at St Germains, fly from the terrace in the king's presence. Hemade the attempt, but merely fell, as did the Saracen some centuriesbefore, causing himself serious injury. Allard cannot be regarded as acontributor to the development of aeronautics in any way, and is onlymentioned as typical of the way in which, up to the time of the Wrightbrothers, flying was regarded. Even unto this day there are many whostill believe that, with a pair of wings, man ought to be able to fly, and that the mathematical data necessary to effective constructionsimply do not exist. This attitude was reasonable enough in anunlearned age, and Allard was one--a little more conspicuous than themajority--among many who made experiment in ignorance, with more or lessdanger to themselves and without practical result of any kind. The seventeenth century was not to end, however, without practicalexperiment of a noteworthy kind in gliding flight. Among the recruits tothe ranks of pioneers was a certain Besnier, a locksmith of Sable, whosomewhere between 1675 and 1680 constructed a glider of which a crudepicture has come down to modern times. The apparatus, as will be seen, consisted of two rods with hinged flaps, and the original designer ofthe picture seems to have had but a small space in which to draw, sinceobviously the flaps must have been much larger than those shown. Besnierplaced the rods on his shoulders, and worked the flaps by cords attachedto his hands and feet--the flaps opened as they fell, and closed as theyrose, so the device as a whole must be regarded as a sort of flappingglider. Having by experiment proved his apparatus successful, Besnierpromptly sold it to a travelling showman of the period, and forthwithset about constructing a second set, with which he made gliding flightsof considerable height and distance. Like Lilienthal, Besnier projectedhimself into space from some height, and then, according to thecontemporary records, he was able to cross a river of considerable sizebefore coming to earth. It does not appear that he had any imitators, or that any advantage whatever was taken of his experiments; the age wasone in which he would be regarded rather as a freak exhibitor than asa serious student, and possibly, considering his origin and the sale ofhis first apparatus to such a client, he regarded the matter himself asmore in the nature of an amusement than as a discovery. Borelli, coming at the end of the century, proved to his ownsatisfaction and that of his fellows that flapping wing flight was animpossibility; the capabilities of the plane were as yet undreamed, andthe prime mover that should make the plane available for flight wasdeep in the womb of time. Da Vinci's work was forgotten--flight was animpossibility, or at best such a useless show as Besnier was able togive. The eighteenth century was almost barren of experiment. EmanuelSwedenborg, having invented a new religion, set about inventing a flyingmachine, and succeeded theoretically, publishing the result of hisinvestigations as follows:-- 'Let a car or boat or some like object be made of light material such ascork or bark, with a room within it for the operator. Secondly, in frontas well as behind, or all round, set a widely-stretched sail parallel tothe machine forming within a hollow or bend which could be reefed likethe sails of a ship. Thirdly, place wings on the sides, to be workedup and down by a spiral spring, these wings also to be hollow below inorder to increase the force and velocity, take in the air, and make theresistance as great as may be required. These, too, should be of lightmaterial and of sufficient size; they should be in the shape of birds'wings, or the sails of a windmill, or some such shape, and should betilted obliquely upwards, and made so as to collapse on the upwardstroke and expand on the downward. Fourth, place a balance or beambelow, hanging down perpendicularly for some distance with a smallweight attached to its end, pendent exactly in line with the centre ofgravity; the longer this beam is, the lighter must it be, for it musthave the same proportion as the well-known vectis or steel-yard. Thiswould serve to restore the balance of the machine if it should lean overto any of the four sides. Fifthly, the wings would perhaps have greaterforce, so as to increase the resistance and make the flight easier, ifa hood or shield were placed over them, as is the case with certaininsects. Sixthly, when the sails are expanded so as to occupy a greatsurface and much air, with a balance keeping them horizontal, only asmall force would be needed to move the machine back and forth in acircle, and up and down. And, after it has gained momentum to moveslowly upwards, a slight movement and an even bearing would keep itbalanced in the air and would determine its direction at will. ' The only point in this worthy of any note is the first device formaintaining stability automatically--Swedenborg certainly scored a pointthere. For the rest, his theory was but theory, incapable of being putto practice--he does not appear to have made any attempt at advancebeyond the mere suggestion. Some ten years before his time the state of knowledge with regard toflying in Europe was demonstrated by an order granted by the King ofPortugal to Friar Lourenzo de Guzman, who claimed to have invented aflying machine capable of actual flight. The order stated that 'Inorder to encourage the suppliant to apply himself with zeal towardthe improvement of the new machine, which is capable of producing theeffects mentioned by him, I grant unto him the first vacant place inmy College of Barcelos or Santarem, and the first professorship ofmathematics in my University of Coimbra, with the annual pension of600, 000 reis during his life. --Lisbon, 17th of March, 1709. ' What happened to Guzman when the non-existence of the machine wasdiscovered is one of the things that is well outside the province ofaeronautics. He was charlatan pure and simple, as far as actual flightwas concerned, though he had some ideas respecting the design of hot-airballoons, according to Tissandier. (La Navigation Aerienne. ) Hisflying machine was to contain, among other devices, bellows to produceartificial wind when the real article failed, and also magnets in globesto draw the vessel in an upward direction and maintain its buoyancy. Some draughtsman, apparently gifted with as vivid imagination as Guzmanhimself, has given to the world an illustration of the hypotheticalvessel; it bears some resemblance to Lana's aerial ship, from which factone draws obvious conclusions. A rather amusing claim to solving the problem of flight was made in themiddle of the eighteenth century by one Grimaldi, a 'famous and uniqueEngineer' who, as a matter of actual fact, spent twenty years inmissionary work in India, and employed the spare time that missionarywork left him in bringing his invention to a workable state. Theinvention is described as a 'box which with the aid of clockwork risesin the air, and goes with such lightness and strong rapidity that itsucceeds in flying a journey of seven leagues in an hour. It is made inthe fashion of a bird; the wings from end to end are 25 feet in extent. The body is composed of cork, artistically joined together and wellfastened with metal wire, covered with parchment and feathers. Thewings are made of catgut and whalebone, and covered also with the sameparchment and feathers, and each wing is folded in three seams. In thebody of the machine are contained thirty wheels of unique work, with twobrass globes and little chains which alternately wind up a counterpoise;with the aid of six brass vases, full of a certain quantity ofquicksilver, which run in some pulleys, the machine is kept by theartist in due equilibrium and balance. By means, then, of the frictionbetween a steel wheel adequately tempered and a very heavy andsurprising piece of lodestone, the whole is kept in a regulated forwardmovement, given, however, a right state of the winds, since the machinecannot fly so much in totally calm weather as in stormy. This prodigiousmachine is directed and guided by a tail seven palmi long, which isattached to the knees and ankles of the inventor by leather straps; bystretching out his legs, either to the right or to the left, he movesthe machine in whichever direction he pleases.... The machine'sflight lasts only three hours, after which the wings gradually closethemselves, when the inventor, perceiving this, goes down gently, so asto get on his own feet, and then winds up the clockwork and gets himselfready again upon the wings for the continuation of a new flight. Hehimself told us that if by chance one of the wheels came off or if oneof the wings broke, it is certain he would inevitably fall rapidly tothe ground, and, therefore, he does not rise more than the height of atree or two, as also he only once put himself in the risk of crossingthe sea, and that was from Calais to Dover, and the same morning hearrived in London. ' And yet there are still quite a number of people who persist in statingthat Bleriot was the first man to fly across the Channel! A study of the development of the helicopter principle was publishedin France in 1868, when the great French engineer Paucton produced hisTheorie de la Vis d'Archimede. For some inexplicable reason, Pauctonwas not satisfied with the term 'helicopter, ' but preferred to call ita 'pterophore, ' a name which, so far as can be ascertained, has not beenadopted by any other writer or investigator. Paucton stated that, sincea man is capable of sufficient force to overcome the weight of his ownbody, it is only necessary to give him a machine which acts on the air'with all the force of which it is capable and at its utmost speed, ' andhe will then be able to lift himself in the air, just as by the exertionof all his strength he is able to lift himself in water. 'It wouldseem, ' says Paucton, 'that in the pterophore, attached vertically to acarriage, the whole built lightly and carefully assembled, he hasfound something that will give him this result in all perfection. Inconstruction, one would be careful that the machine produced the leastfriction possible, and naturally it ought to produce little, as it wouldnot be at all complicated. The new Daedalus, sitting comfortably in hiscarriage, would by means of a crank give to the pterophore a suitablecircular (or revolving) speed. This single pterophore would lift himvertically, but in order to move horizontally he should be supplied witha tail in the shape of another pterophore. When he wished to stop for alittle time, valves fixed firmly across the end of the space betweenthe blades would automatically close the openings through which the airflows, and change the pterophore into an unbroken surface whichwould resist the flow of air and retard the fall of the machine to aconsiderable degree. ' The doctrine thus set forth might appear plausible, but it is based onthe common misconception that all the force which might be put into thehelicopter or 'pterophore' would be utilised for lifting or propellingthe vehicle through the air, just as a propeller uses all its power todrive a ship through water. But, in applying such a propelling forceto the air, most of the force is utilised in maintaining aerodynamicsupport--as a matter of fact, more force is needed to maintain thissupport than the muscle of man could possibly furnish to a liftingscrew, and even if the helicopter were applied to a full-sized, engine-driven air vehicle, the rate of ascent would depend on the amountof surplus power that could be carried. For example, an upward liftof 1, 000 pounds from a propeller 15 feet in diameter would demand anexpenditure of 50 horse-power under the best possible conditions, and inorder to lift this load vertically through such atmospheric pressure asexists at sea-level or thereabouts, an additional 20 horsepower would berequired to attain a rate of 11 feet per second--50 horse-power mustbe continually provided for the mere support of the load, and theadditional 20 horse-power must be continually provided in order tolift it. Although, in model form, there is nothing quite so strikinglysuccessful as the helicopter in the range of flying machines, yet theessential weight increases so disproportionately to the effective areathat it is necessary to go but very little beyond model dimensions forthe helicopter to become quite ineffective. That is not to say that the lifting screw must be totally ruled outso far as the construction of aircraft is concerned. Much is stillempirical, so far as this branch of aeronautics is concerned, andconsideration of the structural features of a propeller goes to showthat the relations of essential weight and effective area do notaltogether apply in practice as they stand in theory. Paucton's dream, in some modified form, may yet become reality--it is only so shorta time ago as 1896 that Lord Kelvin stated he had not the smallestmolecule of faith in aerial navigation, and since the whole history offlight consists in proving the impossible possible, the helicopter mayyet challenge the propelled plane surface for aerial supremacy. It does not appear that Paucton went beyond theory, nor is there in histheory any advance toward practical flight--da Vinci could have toldhim as much as he knew. He was followed by Meerwein, who invented anapparatus apparently something between a flapping wing machine and aglider, consisting of two wings, which were to be operated by means of arod; the venturesome one who would fly by means of this apparatus had tolie in a horizontal position beneath the wings to work the rod. Meerweindeserves a place of mention, however, by reason of his investigationsinto the amount of surface necessary to support a given weight. Takingthat weight at 200 pounds--which would allow for the weight of a manand a very light apparatus--he estimated that 126 square feet would benecessary for support. His pamphlet, published at Basle in 1784, showshim to have been a painstaking student of the potentialities of flight. Jean-Pierre Blanchard, later to acquire fame in connection with balloonflight, conceived and described a curious vehicle, of which he evenannounced trials as impending. His trials were postponed time aftertime, and it appears that he became convinced in the end of the futilityof his device, being assisted to such a conclusion by Lalande, theastronomer, who repeated Borelli's statement that it was impossible forman ever to fly by his own strength. This was in the closing days ofthe French monarchy, and the ascent of the Montgolfiers' first hot-airballoon in 1783--which shall be told more fully in its place--put anend to all French experiments with heavier-than-air apparatus, though inEngland the genius of Cayley was about to bud, and even in France therewere those who understood that ballooning was not true flight. III. SIR GEORGE CAYLEY--THOMAS WALKER On the fifth of June, 1783, the Montgolfiers' hot-air balloon rose atVersailles, and in its rising divided the study of the conquest of theair into two definite parts, the one being concerned with thepropulsion of gas lifted, lighter-than-air vehicles, and the other beingcrystallised in one sentence by Sir George Cayley: 'The whole problem, 'he stated, 'is confined within these limits, viz. : to make a surfacesupport a given weight by the application of power to the resistance ofthe air. ' For about ten years the balloon held the field entirely, beingregarded as the only solution of the problem of flight that man couldever compass. So definite for a time was this view on the eastern sideof the Channel that for some years practically all the progress that wasmade in the development of power-driven planes was made in Britain. In 1800 a certain Dr Thomas Young demonstrated that certain curvedsurfaces suspended by a thread moved into and not away from a horizontalcurrent of air, but the demonstration, which approaches perilously nearto perpetual motion if the current be truly horizontal, has never beensuccessfully repeated, so that there is more than a suspicion thatYoung's air-current was NOT horizontal. Others had made and were makingexperiments on the resistance offered to the air by flat surfaces, whenCayley came to study and record, earning such a place among the pioneersas to win the title of 'father of British aeronautics. ' Cayley was a man in advance of his time, in many ways. Of independentmeans, he made the grand tour which was considered necessary to theeducation of every young man of position, and during this excursion hewas more engaged in studies of a semi-scientific character than in thepursuits that normally filled such a period. His various writings provethat throughout his life aeronautics was the foremost subject in hismind; the Mechanic's Magazine, Nicholson's Journal, the PhilosophicalMagazine, and other periodicals of like nature bear witness to Cayley'scontinued research into the subject of flight. He approached the subjectafter the manner of the trained scientist, analysing the mechanicalproperties of air under chemical and physical action. Then he set towork to ascertain the power necessary for aerial flight, and was one ofthe first to enunciate the fallacy of the hopes of successful flight bymeans of the steam engine of those days, owing to the fact that it wasimpossible to obtain a given power with a given weight. Yet his conclusions on this point were not altogether negative, for asearly as 1810 he stated that he could construct a balloon which couldtravel with passengers at 20 miles an hour--he was one of the first toconsider the possibilities of applying power to a balloon. Nearly thirtyyears later--in 1837--he made the first attempt at establishing anaeronautical society, but at that time the power-driven plane wasregarded by the great majority as an absurd dream of more or less madinventors, while ballooning ranked on about the same level as tight-ropewalking, being considered an adjunct to fairs and fetes, more a pastimethan a study. Up to the time of his death, in 1857, Cayley maintained his study ofaeronautical matters, and there is no doubt whatever that his workwent far in assisting the solution of the problem of air conquest. Hisprincipal published work, a monograph entitled Aerial Navigation, hasbeen republished in the admirable series of 'Aeronautical Classics'issued by the Royal Aeronautical Society. He began this work bypointing out the impossibility of flying by means of attached wings, animpossibility due to the fact that, while the pectoral muscles of a birdaccount for more than two-thirds of its whole muscular strength, in aman the muscles available for flying, no matter what mechanism might beused, would not exceed one-tenth of his total strength. Cayley did not actually deny the possibility of a man flying by musculareffort, however, but stated that 'the flight of a strong man by greatmuscular exertion, though a curious and interesting circumstance, inasmuch as it will probably be the means of ascertaining finis powerand supplying the basis whereon to improve it, would be of little use. ' From this he goes on to the possibility of using a Boulton and Wattsteam engine to develop the power necessary for flight, and in this hesaw a possibility of practical result. It is worthy of note that inthis connection he made mention of the forerunner of the modern internalcombustion engine; 'The French, ' he said, 'have lately shown the greatpower produced by igniting inflammable powders in closed vessels, and several years ago an engine was made to work in this country ina similar manner by inflammation of spirit of tar. ' In a subsequentparagraph of his monograph he anticipates almost exactly theconstruction of the Lenoir gas engine, which came into being more thanfifty-five years after his monograph was published. Certain experiments detailed in his work were made to ascertain thesize of the surface necessary for the support of any given weight. He accepted a truism of to-day in pointing out that in any mattersconnected with aerial investigation, theory and practice are aswidely apart as the poles. Inclined at first to favour the helicopterprinciple, he finally rejected this in favour of the plane, with whichhe made numerous experiments. During these, he ascertained the peculiaradvantages of curved surfaces, and saw the necessity of providing bothvertical and horizontal rudders in order to admit of side steeringas well as the control of ascent and descent, and for preservingequilibrium. He may be said to have anticipated the work of Lilienthaland Pilcher, since he constructed and experimented with a fixed surfaceglider. 'It was beautiful, ' he wrote concerning this, 'to see this noblewhite bird sailing majestically from the top of a hill to any givenpoint of the plain below it with perfect steadiness and safety, according to the set of its rudder, merely by its own weight, descendingat an angle of about eight degrees with the horizon. ' It is said that he once persuaded his gardener to trust himself in thisglider for a flight, but if Cayley himself ventured a flight in it hehas left no record of the fact. The following extract from his work, Aerial Navigation, affords an instance of the thoroughness of hisinvestigations, and the concluding paragraph also shows his faith in theultimate triumph of mankind in the matter of aerial flight:-- 'The act of flying requires less exertion than from the appearance issupposed. Not having sufficient data to ascertain the exact degree ofpropelling power exerted by birds in the act of flying, it is uncertainwhat degree of energy may be required in this respect for vessels ofaerial navigation; yet when we consider the many hundreds of miles ofcontinued flight exerted by birds of passage, the idea of its being onlya small effort is greatly corroborated. To apply the power of the firstmover to the greatest advantage in producing this effect is a verymaterial point. The mode universally adopted by Nature is the obliquewaft of the wing. We have only to choose between the direct beatovertaking the velocity of the current, like the oar of a boat, orone applied like the wing, in some assigned degree of obliquity to it. Suppose 35 feet per second to be the velocity of an aerial vehicle, theoar must be moved with this speed previous to its being able to receiveany resistance; then if it be only required to obtain a pressure ofone-tenth of a lb. Upon each square foot it must exceed the velocity ofthe current 7. 3 feet per second. Hence its whole velocity must be 42. 5feet per second. Should the same surface be wafted downward like a wingwith the hinder edge inclined upward in an angle of about 50 deg. 40feet to the current it will overtake it at a velocity of 3. 5 feet persecond; and as a slight unknown angle of resistance generates a lb. Pressure per square foot at this velocity, probably a waft of a littlemore than 4 feet per second would produce this effect, one-tenth partof which would be the propelling power. The advantage of this mode ofapplication compared with the former is rather more than ten to one. 'In continuing the general principles of aerial navigation, for thepractice of the art, many mechanical difficulties present themselveswhich require a considerable course of skilfully applied experimentsbefore they can be overcome; but, to a certain extent, the air hasalready been made navigable, and no one who has seen the steadinesswith which weights to the amount of ten stone (including four stone, the weight of the machine) hover in the air can doubt of the ultimateaccomplishment of this object. ' This extract from his work gives but a faint idea of the amount ofresearch for which Cayley was responsible. He had the humility of thetrue investigator in scientific problems, and so far as can be seenwas never guilty of the great fault of so many investigators in thissubject--that of making claims which he could not support. He wascontent to do, and pass after having recorded his part, and althoughnearly half a century had to pass between the time of his death and thefirst actual flight by means of power-driven planes, yet he may be saidto have contributed very largely to the solution of the problem, and hisname will always rank high in the roll of the pioneers of flight. Practically contemporary with Cayley was Thomas Walker, concerning whomlittle is known save that he was a portrait painter of Hull, wherewas published his pamphlet on The Art of Flying in 1810, a second andamplified edition being produced, also in Hull, in 1831. The pamphlet, which has been reproduced in extenso in the Aeronautical Classics seriespublished by the Royal Aeronautical Society, displays a curious mixtureof the true scientific spirit and colossal conceit. Walker appears tohave been a man inclined to jump to conclusions, which carried him up tothe edge of discovery and left him vacillating there. The study of the two editions of his pamphlet side by side shows thattheir author made considerable advances in the practicability of hisdesigns in the 21 intervening years, though the drawings which accompanythe text in both editions fail to show anything really capableof flight. The great point about Walker's work as a whole is itssuggestiveness; he did not hesitate to state that the 'art' of flying isas truly mechanical as that of rowing a boat, and he had some conceptionof the necessary mechanism, together with an absolute conviction that heknew all there was to be known. 'Encouraged by the public, ' he says, 'I would not abandon my purpose of making still further exertions toadvance and complete an art, the discovery of the TRUE PRINCIPLES (theitalics are Walker's own) of which, I trust, I can with certainty affirmto be my own. ' The pamphlet begins with Walker's admiration of the mechanism of flightas displayed by birds. 'It is now almost twenty years, ' he says, 'sinceI was first led to think, by the study of birds and their means offlying, that if an artificial machine were formed with wings in exactimitation of the mechanism of one of those beautiful living machines, and applied in the very same way upon the air, there could be no doubtof its being made to fly, for it is an axiom in philosophy that the samecause will ever produce the same effect. ' With this he confesses hisinability to produce the said effect through lack of funds, though heclothes this delicately in the phrase 'professional avocations and othercircumstances. ' Owing to this inability he published his designs thatothers might take advantage of them, prefacing his own researches witha list of the very early pioneers, and giving special mention toFriar Bacon, Bishop Wilkins, and the Portuguese friar, De Guzman. But, although he seems to suggest that others should avail themselves ofhis theoretical knowledge, there is a curious incompleteness about thedesigns accompanying his work, and about the work itself, which seemsto suggest that he had more knowledge to impart than he chose to makepublic--or else that he came very near to complete solution of theproblem of flight, and stayed on the threshold without knowing it. After a dissertation upon the history and strength of the condor, andon the differences between the weights of birds, he says: 'The followingobservations upon the wonderful difference in the weight of some birds, with their apparent means of supporting it in their flight, may tendto remove some prejudices against my plan from the minds of some ofmy readers. The weight of the humming-bird is one drachm, that of thecondor not less than four stone. Now, if we reduce four stone intodrachms we shall find the condor is 14, 336 times as heavy as thehumming-bird. What an amazing disproportion of weight! Yet by the samemechanical use of its wings the condor can overcome the specific gravityof its body with as much ease as the little humming-bird. But this isnot all. We are informed that this enormous bird possesses a power inits wings, so far exceeding what is necessary for its own conveyancethrough the air, that it can take up and fly away with a whole sheer inits talons, with as much ease as an eagle would carry off, in the samemanner, a hare or a rabbit. This we may readily give credit to, from theknown fact of our little kestrel and the sparrow-hawk frequently flyingoff with a partridge, which is nearly three times the weight of theserapacious little birds. ' After a few more observations he arrives at the following conclusion:'By attending to the progressive increase in the weight of birds, fromthe delicate little humming-bird up to the huge condor, we clearlydiscover that the addition of a few ounces, pounds, or stones, is noobstacle to the art of flying; the specific weight of birds availsnothing, for by their possessing wings large enough, and sufficientpower to work them, they can accomplish the means of flying equally wellupon all the various scales and dimensions which we see in nature. Suchbeing a fact, in the name of reason and philosophy why shall not man, with a pair of artificial wings, large enough, and with sufficient powerto strike them upon the air, be able to produce the same effect?' Walker asserted definitely and with good ground that muscular effortapplied without mechanism is insufficient for human flight, but hestates that if an aeronautical boat were constructed so that a man couldsit in it in the same manner as when rowing, such a man would be able tobring into play his whole bodily strength for the purpose of flight, and at the same time would be able to get an additional advantage byexerting his strength upon a lever. At first he concluded there mustbe expansion of wings large enough to resist in a sufficient degreethe specific gravity of whatever is attached to them, but in the secondedition of his work he altered this to 'expansion of flat passivesurfaces large enough to reduce the force of gravity so as to floatthe machine upon the air with the man in it. ' The second requisite isstrength enough to strike the wings with sufficient force to completethe buoyancy and give a projectile motion to the machine. Giventhese two requisites, Walker states definitely that flying must beaccomplished simply by muscular exertion. 'If we are secure of these tworequisites, and I am very confident we are, we may calculate upon thesuccess of flight with as much certainty as upon our walking. ' Walker appears to have gained some confidence from the experiments of acertain M. Degen, a watchmaker of Vienna, who, according to the MonthlyMagazine of September, 1809, invented a machine by means of which aperson might raise himself into the air. The said machine, according tothe magazine, was formed of two parachutes which might be folded up orextended at pleasure, while the person who worked them was placed in thecentre. This account, however, was rather misleading, for the magazinecarefully avoided mention of a balloon to which the inventor fixed hiswings or parachutes. Walker, knowing nothing of the balloon, concludedthat Degen actually raised himself in the air, though he is doubtfulof the assertion that Degen managed to fly in various directions, especially against the wind. Walker, after considering Degen and all his works, proceeds to detailhis own directions for the construction of a flying machine, thesebeing as follows: 'Make a car of as light material as possible, butwith sufficient strength to support a man in it; provide a pair of wingsabout four feet each in length; let them be horizontally expanded andfastened upon the top edge of each side of the car, with two jointseach, so as to admit of a vertical motion to the wings, which motion maybe effected by a man sitting and working an upright lever in the middleof the car. Extend in the front of the car a flat surface of silk, whichmust be stretched out and kept fixed in a passive state; there mustbe the same fixed behind the car; these two surfaces must be perfectlyequal in length and breadth and large enough to cover a sufficientquantity of air to support the whole weight as nearly in equilibrium aspossible, thus we shall have a great sustaining power in those passivesurfaces and the active wings will propel the car forward. ' A description of how to launch this car is subsequently given: 'Itbecomes necessary, ' says the theorist, 'that I should give directionshow it may be launched upon the air, which may be done by various means;perhaps the following method may be found to answer as well as any: Fixa poll upright in the earth, about twenty feet in height, with two opencollars to admit another poll to slide upwards through them; let therebe a sliding platform made fast upon the top of the sliding poll; placethe car with a man in it upon the platform, then raise the platform tothe height of about thirty feet by means of the sliding poll, let thesliding poll and platform suddenly fall down, the car will then beleft upon the air, and by its pressing the air a projectile force willinstantly propel the car forward; the man in the car must then strikethe active wings briskly upon the air, which will so increase theprojectile force as to become superior to the force of gravitation, andif he inclines his weight a little backward, the projectile impulse willdrive the car forward in an ascending direction. When the car is broughtto a sufficient altitude to clear the tops of hills, trees, buildings, etc. , the man, by sitting a little forward on his seat, will then bringthe wings upon a horizontal plane, and by continuing the action of thewings he will be impelled forward in that direction. To descend, hemust desist from striking the wings, and hold them on a level with theirjoints; the car will then gradually come down, and when it is withinfive or six feet of the ground the man must instantly strike the wingsdownwards, and sit as far back as he can; he will by this means checkthe projectile force, and cause the car to alight very gently with aretrograde motion. The car, when up in the air, may be made to turnto the right or to the left by forcing out one of the fins, having oneabout eighteen inches long placed vertically on each side of the car forthat purpose, or perhaps merely by the man inclining the weight of hisbody to one side. ' Having stated how the thing is to be done, Walker is careful to explainthat when it is done there will be in it some practical use, notably inrespect of the conveyance of mails and newspapers, or the saving oflife at sea, or for exploration, etc. It might even reduce the number ofhorses kept by man for his use, by means of which a large amount of landmight be set free for the growth of food for human consumption. At the end of his work Walker admits the idea of steam power for drivinga flying machine in place of simple human exertion, but he, like Cayley, saw a drawback to this in the weight of the necessary engine. On thewhole, he concluded, navigation of the air by means of engine powerwould be mostly confined to the construction of navigable balloons. As already noted, Walker's work is not over practical, and the foregoingextract includes the most practical part of it; the rest is a seriesof dissertations on bird flight, in which, evidently, the portraitpainter's observations were far less thorough than those of da Vinci orBorelli. Taken on the whole, Walker was a man with a hobby; he devotedto it much time and thought, but it remained a hobby, nevertheless. Hisobservations have proved useful enough to give him a place among theearly students of flight, but a great drawback to his work is the lackof practical experiment, by means of which alone real advance couldbe made; for, as Cayley admitted, theory and practice are very widelyseparated in the study of aviation, and the whole history of flight isa matter of unexpected results arising from scarcely foreseen causes, together with experiment as patient as daring. IV. THE MIDDLE NINETEENTH CENTURY Both Cayley and Walker were theorists, though Cayley supported histheoretical work with enough of practice to show that he studied alongright lines; a little after his time there came practical menwho brought to being the first machine which actually flew by theapplication of power. Before their time, however, mention must be madeof the work of George Pocock of Bristol, who, somewhere about 1840invented what was described as a 'kite carriage, ' a vehicle whichcarried a number of persons, and obtained its motive power from a largekite. It is on record that, in the year 1846 one of these carriagesconveyed sixteen people from Bristol to London. Another device ofPocock's was what he called a 'buoyant sail, ' which was in effect aman-lifting kite, and by means of which a passenger was actually raised100 yards from the ground, while the inventor's son scaled a cliff200 feet in height by means of one of these, 'buoyant sails. ' Thisconstitutes the first definitely recorded experiment in the use ofman-lifting kites. A History of the Charvolant or Kite-carriage, published in London in 1851, states that 'an experiment of a bold andvery novel character was made upon an extensive down, where a largewagon with a considerable load was drawn along, whilst this huge machineat the same time carried an observer aloft in the air, realising almostthe romance of flying. ' Experimenting, two years after the appearance of the 'kite-carriage, 'on the helicopter principle, W. H. Phillips constructed a model machinewhich weighed two pounds; this was fitted with revolving fans, drivenby the combustion of charcoal, nitre, and gypsum, producing steam which, discharging into the air, caused the fans to revolve. The inventorstated that 'all being arranged, the steam was up in a few seconds, whenthe whole apparatus spun around like any top, and mounted into theair faster than a bird; to what height it ascended I had no means ofascertaining; the distance travelled was across two fields, where, aftera long search, I found the machine minus the wings, which had beentorn off in contact with the ground. ' This could hardly be described assuccessful flight, but it was an advance in the construction of machineson the helicopter principle, and it was the first steam-driven model ofthe type which actually flew. The invention, however, was not followedup. After Phillips, we come to the great figures of the middle nineteenthcentury, W. S. Henson and John Stringfellow. Cayley had shown, in1809, how success might be attained by developing the idea of the planesurface so driven as to take advantage of the resistance offered bythe air, and Henson, who as early as 1840 was experimenting with modelgliders and light steam engines, evolved and patented an idea forsomething very nearly resembling the monoplane of the early twentiethcentury. His patent, No. 9478, of the year 1842 explains the principleof the machine as follows:-- In order that the description hereafter given be rendered clear, I willfirst shortly explain the principle on which the machine is constructed. If any light and flat or nearly flat article be projected or thrownedgewise in a slightly inclined position, the same will rise on theair till the force exerted is expended, when the article so thrown orprojected will descend; and it will readily be conceived that, if thearticle so projected or thrown possessed in itself a continuous power orforce equal to that used in throwing or projecting it, the articlewould continue to ascend so long as the forward part of the surface wasupwards in respect to the hinder part, and that such article, when thepower was stopped, or when the inclination was reversed, would descendby gravity aided by the force of the power contained in the article, ifthe power be continued, thus imitating the flight of a bird. Now, the first part of my invention consists of an apparatus soconstructed as to offer a very extended surface or plane of a light yetstrong construction, which will have the same relation to the generalmachine which the extended wings of a bird have to the body when a birdis skimming in the air; but in place of the movement or power for onwardprogress being obtained by movement of the extended surface or plane, asis the case with the wings of birds, I apply suitable paddle-wheelsor other proper mechanical propellers worked by a steam or othersufficiently light engine, and thus obtain the requisite power foronward movement to the plane or extended surface; and in order to givecontrol as to the upward and downward direction of such a machine Iapply a tail to the extended surface which is capable of being inclinedor raised, so that when the power is acting to propel the machine, byinclining the tail upwards, the resistance offered by the air willcause the machine to rise on the air; and, on the contrary, when theinclination of the tail is reversed, the machine will immediately bepropelled downwards, and pass through a plane more or less inclined tothe horizon as the inclination of the tail is greater or less; and inorder to guide the machine as to the lateral direction which it shalltake, I apply a vertical rudder or second tail, and, according as thesame is inclined in one direction or the other, so will be the directionof the machine. ' The machine in question was very large, and differed very little fromthe modern monoplane; the materials were to be spars of bamboo andhollow wood, with diagonal wire bracing. The surface of the planes wasto amount to 4, 500 square feet, and the tail, triangular in form (heremodern practice diverges) was to be 1, 500 square feet. The inventorestimated that there would be a sustaining power of half a pound persquare foot, and the driving power was to be supplied by a steam engineof 25 to 30 horse-power, driving two six-bladed propellers. Henson waslargely dependent on Stringfellow for many details of his design, moreespecially with regard to the construction of the engine. The publication of the patent attracted a great amount of publicattention, and the illustrations in contemporary journals, representingthe machine flying over the pyramids and the Channel, anticipated factby sixty years and more; the scientific world was divided, as it wasup to the actual accomplishment of flight, as to the value of theinvention. Strongfellow and Henson became associated after the conception of theirdesign, with an attorney named Colombine, and a Mr Marriott, andbetween the four of them a project grew for putting the whole thing ona commercial basis--Henson and Stringfellow were to supply the idea;Marriott, knowing a member of Parliament, would be useful in getting acompany incorporated, and Colombine would look after the purely legalside of the business. Thus an application was made by Mr Roebuck, Marriott's M. P. , for an act of incorporation for 'The Aerial SteamTransit Company, ' Roebuck moving to bring in the bill on the 24th ofMarch, 1843. The prospectus, calling for funds for the development ofthe invention, makes interesting reading at this stage of aeronauticaldevelopment; it was as follows: PROPOSAL. For subscriptions of sums of L100, in furtherance of an ExtraordinaryInvention not at present safe to be developed by securing the necessaryPatents, for which three times the sum advanced, namely, L300, isconditionally guaranteed for each subscription on February 1, 1844, in case of the anticipations being realised, with the option of thesubscribers being shareholders for the large amount if so desired, butnot otherwise. ---------An Invention has recently been discovered, which if ultimatelysuccessful will be without parallel even in the age which introduced tothe world the wonderful effects of gas and of steam. The discovery is of that peculiar nature, so simple in principle yetso perfect in all the ingredients required for complete and permanentsuccess, that to promulgate it at present would wholly defeat itsdevelopment by the immense competition which would ensue, and the viewsof the originator be entirely frustrated. This work, the result of years of labour and study, presents a wonderfulinstance of the adaptation of laws long since proved to the scientificworld combined with established principles so judiciously and carefullyarranged, as to produce a discovery perfect in all its parts and alikein harmony with the laws of Nature and of science. The Invention has been subjected to several tests and examinationsand the results are most satisfactory so much so that nothing but thecompletion of the undertaking is required to determine its practicaloperation, which being once established its utility is undoubted, as itwould be a necessary possession of every empire, and it were hardly toomuch to say, of every individual of competent means in the civilisedworld. Its qualities and capabilities are so vast that it were impossible and, even if possible, unsafe to develop them further, but some idea maybe formed from the fact that as a preliminary measure patents in GreatBritain Ireland, Scotland, the Colonies, France, Belgium, and theUnited States, and every other country where protection to the firstdiscoveries of an Invention is granted, will of necessity be immediatelyobtained, and by the time these are perfected, which it is estimatedwill be in the month of February, the Invention will be fit for PublicTrial, but until the Patents are sealed any further disclosure would bemost dangerous to the principle on which it is based. Under these circumstances, it is proposed to raise an immediate sum ofL2, 000 in furtherance of the Projector's views, and as some protectionto the parties who may embark in the matter, that this is not avisionary plan for objects imperfectly considered, Mr Colombine, to whomthe secret has been confided, has allowed his name to be used on theoccasion, and who will if referred to corroborate this statement, andconvince any inquirer of the reasonable prospects of large pecuniaryresults following the development of the Invention. It is, therefore, intended to raise the sum of L2, 000 in twenty sums ofL100 each (of which any subscriber may take one or more not exceedingfive in number to be held by any individual) the amount of which is tobe paid into the hands of Mr Colombine as General Manager of the concernto be by him appropriated in procuring the several Patents and providingthe expenses incidental to the works in progress. For each of whichsums of L100 it is intended and agreed that twelve months after the1st February next, the several parties subscribing shall receive as anequivalent for the risk to be run the sum of L300 for each of the sumsof L100 now subscribed, provided when the time arrives the Patents shallbe found to answer the purposes intended. As full and complete success is alone looked to, no moderate orimperfect benefit is to be anticipated, but the work, if it once passesthe necessary ordeal, to which inventions of every kind must be firstsubject, will then be regarded by every one as the most astonishingdiscovery of modern times; no half success can follow, and therefore thefull nature of the risk is immediately ascertained. The intention is to work and prove the Patent by collective instead ofindividual aid as less hazardous at first end more advantageous in theresult for the Inventor, as well as others, by having the interest ofseveral engaged in aiding one common object--the development of aGreat Plan. The failure is not feared, yet as perfect success might, bypossibility, not ensue, it is necessary to provide for that result, and the parties concerned make it a condition that no return ofthe subscribed money shall be required, if the Patents shall by anyunforeseen circumstances not be capable of being worked at all; againstwhich, the first application of the money subscribed, that of securingthe Patents, affords a reasonable security, as no one without solidgrounds would think of such an expenditure. It is perfectly needless to state that no risk or responsibility of anykind can arise beyond the payment of the sum to be subscribed under anycircumstances whatever. As soon as the Patents shall be perfected and proved it is contemplated, so far as may be found practicable, to further the great object in viewa Company shall be formed but respecting which it is unnecessary tostate further details, than that a preference will be given to all thosepersons who now subscribe, and to whom shares shall be appropriatedaccording to the larger amount (being three times the sum to be paid byeach person) contemplated to be returned as soon as the success of theInvention shall have been established, at their option, or the moneypaid, whereby the Subscriber will have the means of either withdrawingwith a large pecuniary benefit, or by continuing his interest in theconcern lay the foundation for participating in the immense benefitwhich must follow the success of the plan. It is not pretended to conceal that the project is a speculation--allparties believe that perfect success, and thence incalculable advantageof every kind, will follow to every individual joining in this greatundertaking; but the Gentlemen engaged in it wish that no concealmentof the consequences, perfect success, or possible failure, should in theslightest degree be inferred. They believe this will prove the germ of amighty work, and in that belief call for the operation of others with novisionary object, but a legitimate one before them, to attain that pointwhere perfect success will be secured from their combined exertions. All applications to be made to D. E. Colombine, Esquire, 8 CarltonChambers, Regent Street. The applications did not materialise, as was only to be expected in viewof the vagueness of the proposals. Colombine did some advertising, andMr Roebuck expressed himself as unwilling to proceed further in theventure. Henson experimented with models to a certain extent, whileStringfellow looked for funds for the construction of a full-sizedmonoplane. In November of 1843 he suggested that he and Henson shouldconstruct a large model out of their own funds. On Henson's suggestionColombine and Marriott were bought out as regards the original patent, and Stringfellow and Henson entered into an agreement and set to work. Their work is briefly described in a little pamphlet by F. J. Stringfellow, entitled A few Remarks on what has been done withscrew-propelled Aero-plane Machines from 1809 to 1892. The author writeswith regard to the work that his father and Henson undertook:-- 'They commenced the construction of a small model operated by a spring, and laid down the larger model 20 ft. From tip to tip of planes, 3 1/2ft. Wide, giving 70 ft. Of sustaining surface, about 10 more in thetail. The making of this model required great consideration; varioussupports for the wings were tried, so as to combine lightness withfirmness, strength and rigidity. 'The planes were staid from three sets of fish-shaped masts, and riggedsquare and firm by flat steel rigging. The engine and boiler were put inthe car to drive two screw-propellers, right and left-handed, 3 ft. Indiameter, with four blades each, occupying three-quarters of the areaof the circumference, set at an angle of 60 degrees. A considerable timewas spent in perfecting the motive power. Compressed air was tried andabandoned. Tappets, cams, and eccentrics were all tried, to work theslide valve, to obtain the best results. The piston rod of engine passedthrough both ends of the cylinder, and with long connecting rods workeddirect on the crank of the propellers. From memorandum of experimentsstill preserved the following is a copy of one: June, 27th, 1845, water50 ozs. , spirit 10 ozs. , lamp lit 8. 45, gauge moves 8. 46, engine started8. 48 (100 lb. Pressure), engine stopped 8. 57, worked 9 minutes, 2, 288revolutions, average 254 per minute. No priming, 40 ozs. Water consumed, propulsion (thrust of propellers), 5 lbs. 4 1/2 ozs. At commencement, steady, 4 lbs. 1/2 oz. , 57 revolutions to 1 oz. Water, steam cut offone-third from beginning. 'The diameter of cylinder of engine was 1 1/2 inch, length of stroke 3inches. 'In the meantime an engine was also made for the smaller model, and awing action tried, but with poor results. The time was mostly devoted tothe larger model, and in 1847 a tent was erected on Bala Down, about twomiles from Chard, and the model taken up one night by the workmen. Theexperiments were not so favourable as was expected. The machine couldnot support itself for any distance, but, when launched off, graduallydescended, although the power and surface should have been ample;indeed, according to latest calculations, the thrust should have carriedmore than three times the weight, for there was a thrust of 5 lbs. Fromthe propellers, and a surface of over 70 square feet to sustain under 30lbs. , but necessary speed was lacking. ' Stringfellow himself explained the failure as follows:-- 'There stood our aerial protegee in all her purity--too delicate, toofragile, too beautiful for this rough world; at least those weremy ideas at the time, but little did I think how soon it was to berealised. I soon found, before I had time to introduce the spark, adrooping in the wings, a flagging in all the parts. In less than tenminutes the machine was saturated with wet from a deposit of dew, sothat anything like a trial was impossible by night. I did not considerwe could get the silk tight and rigid enough. Indeed, the frameworkaltogether was too weak. The steam-engine was the best part. Our want ofsuccess was not for want of power or sustaining surface, but for want ofproper adaptation of the means to the end of the various parts. ' Henson, who had spent a considerable amount of money in theseexperimental constructions, consoled himself for failure by venturinginto matrimony; in 1849 he went to America, leaving Stringfellow tocontinue experimenting alone. From 1846 to 1848 Stringfellow worked onwhat is really an epoch-making item in the history of aeronautics--thefirst engine-driven aeroplane which actually flew. The machine inquestion had a 10 foot span, and was 2 ft. Across in the widest part ofthe wing; the length of tail was 3 ft. 6 ins. , and the span of tail inthe widest part 22 ins. , the total sustaining area being about 14sq. Ft. The motive power consisted of an engine with a cylinder ofthree-quarter inch diameter and a two-inch stroke; between this andthe crank shaft was a bevelled gear giving three revolutions of thepropellers to every stroke of the engine; the propellers, right and leftscrew, were four-bladed and 16 inches in diameter. The total weight ofthe model with engine was 8 lbs. Its successful flight is ascribed tothe fact that Stringfellow curved the wings, giving them rigid frontedges and flexible trailing edges, as suggested long before both by DaVinci and Borelli, but never before put into practice. Mr F. J. Stringfellow, in the pamphlet quoted above, gives the bestaccount of the flight of this model: 'My father had constructed anothersmall model which was finished early in 1848, and having the loan of along room in a disused lace factory, early in June the small model wasmoved there for experiments. The room was about 22 yards long andfrom 10 to 12 ft. High.... The inclined wire for starting the machineoccupied less than half the length of the room and left space at the endfor the machine to clear the floor. In the first experiment the tail wasset at too high an angle, and the machine rose too rapidly on leavingthe wire. After going a few yards it slid back as if coming down aninclined plane, at such an angle that the point of the tail struck theground and was broken. The tail was repaired and set at a smaller angle. The steam was again got up, and the machine started down the wire, and, upon reaching the point of self-detachment, it gradually rose untilit reached the farther end of the room, striking a hole in the canvasplaced to stop it. In experiments the machine flew well, when rising asmuch as one in seven. The late Rev. J. Riste, Esq. , lace manufacturer, Northcote Spicer, Esq. , J. Toms, Esq. , and others witnessed experiments. Mr Marriatt, late of the San Francisco News Letter brought down fromLondon Mr Ellis, the then lessee of Cremorne Gardens, Mr Partridge, andLieutenant Gale, the aeronaut, to witness experiments. Mr Ellis offeredto construct a covered way at Cremorne for experiments. Mr Stringfellowrepaired to Cremorne, but not much better accommodations than he hadat home were provided, owing to unfulfilled engagement as to room. Mr Stringfellow was preparing for departure when a party of gentlemenunconnected with the Gardens begged to see an experiment, and findingthem able to appreciate his endeavours, he got up steam and started themodel down the wire. When it arrived at the spot where it should leavethe wire it appeared to meet with some obstruction, and threatened tocome to the ground, but it soon recovered itself and darted off inas fair a flight as it was possible to make at a distance of about 40yards, where it was stopped by the canvas. 'Having now demonstrated the practicability of making a steam-enginefly, and finding nothing but a pecuniary loss and little honour, this experimenter rested for a long time, satisfied with what he hadeffected. The subject, however, had to him special charms, and he stillcontemplated the renewal of his experiments. ' It appears that Stringfellow's interest did not revive sufficientlyfor the continuance of the experiments until the founding of theAeronautical Society of Great Britain in 1866. Wenham's paper on AerialLocomotion read at the first meeting of the Society, which was held atthe Society of Arts under the Presidency of the Duke of Argyll, wasthe means of bringing Stringfellow back into the field. It was Wenham'ssuggestion, in the first place, that monoplane design should beabandoned for the superposition of planes; acting on this suggestionStringfellow constructed a model triplane, and also designed a steamengine of slightly over one horse-power, and a one horse-power copperboiler and fire box which, although capable of sustaining a pressure of500 lbs. To the square inch, weighed only about 40 lbs. Both the engine and the triplane model were exhibited at the firstAeronautical Exhibition held at the Crystal Palace in 1868. The triplanehad a supporting surface of 28 sq. Ft. ; inclusive of engine, boiler, fuel, and water its total weight was under 12 lbs. The engine worked two21 in. Propellers at 600 revolutions per minute, and developed 100 lbs. Steam pressure in five minutes, yielding one-third horse-power. Sinceno free flight was allowed in the Exhibition, owing to danger from fire, the triplane was suspended from a wire in the nave of the building, and it was noted that, when running along the wire, the model made aperceptible lift. A prize of L100 was awarded to the steam engine as the lightest steamengine in proportion to its power. The engine and model together maybe reckoned as Stringfellow's best achievement. He used his L100 inpreparation for further experiments, but he was now an old man, andhis work was practically done. Both the triplane and the engine wereeventually bought for the Washington Museum; Stringfellow's earliermodels, together with those constructed by him in conjunction withHenson, remain in this country in the Victoria and Albert Museum. John Stringfellow died on December 13th, 1883. His place in the historyof aeronautics is at least equal to that of Cayley, and it may besaid that he laid the foundation of such work as was subsequentlyaccomplished by Maxim, Langley, and their fellows. It was the coming ofthe internal combustion engine that rendered flight practicable, and hadthis prime mover been available in John Stringfellow's day the Wrightbrothers' achievement might have been antedated by half a century. V. WENHAM, LE BRIS, AND SOME OTHERS There are few outstanding events in the development of aeronauticsbetween Stringfellow's final achievement and the work of such men asLilienthal, Pilcher, Montgomery, and their kind; in spite of this, thelater middle decades of the nineteenth century witnessed a considerableamount of spade work both in England and in France, the two countrieswhich led in the way in aeronautical development until Lilienthal gavehonour to Germany, and Langley and Montgomery paved the way for theWright Brothers in America. Two abortive attempts characterised the sixties of last century inFrance. As regards the first of these, it was carried out by three men, Nadar, Ponton d'Amecourt, and De la Landelle, who conceived the ideaof a full-sized helicopter machine. D'Amecourt exhibited a steam model, constructed in 1865, at the Aeronautical Society's Exhibition in 1868. The engine was aluminium with cylinders of bronze, driving two screwsplaced one above the other and rotating in Opposite directions, but thepower was not sufficient to lift the model. De la Landelle's principalachievement consisted in the publication in 1863 of a book entitledAviation which has a certain historical value; he got out severaldesigns for large machines on the helicopter principle, but did littlemore until the three combined in the attempt to raise funds for theconstruction of their full-sized machine. Since the funds were notforthcoming, Nadar took to ballooning as the means of raising money;apparently he found this substitute for real flight sufficientlyinteresting to divert him from the study of the helicopter principle, for the experiment went no further. The other experimenter of this period, one Count d'Esterno, took out apatent in 1864 for a soaring machine which allowed for alteration ofthe angle of incidence of the wings in the manner that was subsequentlycarried out by the Wright Brothers. It was not until 1883 that anyattempt was made to put this patent to practical use, and, as theinventor died while it was under construction, it was never completed. D'Esterno was also responsible for the production of a work entitledDu Vol des Oiseaux, which is a very remarkable study of the flight ofbirds. Mention has already been made of the founding of the AeronauticalSociety of Great Britain, which, since 1918 has been the RoyalAeronautical Society. 1866 witnessed the first meeting of the Societyunder the Presidency of the Duke of Argyll, when in June, at the Societyof Arts, Francis Herbert Wenham read his now classic paper AerialLocomotion. Certain quotations from this will show how clearly Wenhamhad thought out the problems connected with flight. 'The first subject for consideration is the proportion of surface toweight, and their combined effect in descending perpendicularly throughthe atmosphere. The datum is here based upon the consideration ofsafety, for it may sometimes be needful for a living being to droppassively, without muscular effort. One square foot of sustainingsurface for every pound of the total weight will be sufficient forsecurity. 'According to Smeaton's table of atmospheric resistances, to producea force of one pound on a square foot, the wind must move against theplane (or which is the same thing, the plane against the wind), at therate of twenty-two feet per second, or 1, 320 feet per minute, equal tofifteen miles per hour. The resistance of the air will now balance theweight on the descending surface, and, consequently, it cannot exceedthat speed. Now, twenty-two feet per second is the velocity acquired atthe end of a fall of eight feet--a height from which a well-knit man oranimal may leap down without much risk of injury. Therefore, if a manwith parachute weigh together 143 lbs. , spreading the same number ofsquare feet of surface contained in a circle fourteen and a half feetin diameter, he will descend at perhaps an unpleasant velocity, but withsafety to life and limb. 'It is a remarkable fact how this proportion of wing-surface to weightextends throughout a great variety of the flying portion of theanimal kingdom, even down to hornets, bees, and other insects. In someinstances, however, as in the gallinaceous tribe, including pheasants, this area is somewhat exceeded, but they are known to be very poorfliers. Residing as they do chiefly on the ground, their wings areonly required for short distances, or for raising them or easing theirdescent from their roosting-places in forest trees, the shortnessof their wings preventing them from taking extended flights. Thewing-surface of the common swallow is rather more than in the ratio oftwo square feet per pound, but having also great length of pinion, it isboth swift and enduring in its flight. When on a rapid course this birdis in the habit of furling its wings into a narrow compass. The greaterextent of surface is probably needful for the continual variations ofspeed and instant stoppages for obtaining its insect food. 'On the other hand, there are some birds, particularly of the ducktribe, whose wing-surface but little exceeds half a square foot, or seventy-two inches per pound, yet they may be classed among thestrongest and swiftest of fliers. A weight of one pound, suspendedfrom an area of this extent, would acquire a velocity due to a fall ofsixteen feet--a height sufficient for the destruction or injury of mostanimals. But when the plane is urged forward horizontally, in a manneranalogous to the wings of a bird during flight, the sustaining power isgreatly influenced by the form and arrangement of the surface. 'In the case of perpendicular descent, as a parachute, the sustainingeffect will be much the same, whatever the figure of the outline of thesuperficies may be, and a circle perhaps affords the best resistance ofany. Take, for example, a circle of twenty square feet (as possessedby the pelican) loaded with as many pounds. This, as just stated, willlimit the rate of perpendicular descent to 1, 320 feet per minute. Butinstead of a circle sixty-one inches in diameter, if the area is boundedby a parallelogram ten feet long by two feet broad, and whilst atperfect freedom to descend perpendicularly, let a force be appliedexactly in a horizontal direction, so as to carry it edgeways, with thelong side foremost, at a forward speed of thirty miles per hour--justdouble that of its passive descent: the rate of fall under theseconditions will be decreased most remarkably, probably to less thanone-fifteenth part, or eighty-eight feet per minute, or one mile perhour. ' And again: 'It has before been shown how utterly inadequate the mereperpendicular impulse of a plane is found to be in supporting a weight, when there is no horizontal motion at the time. There is no materialweight of air to be acted upon, and it yields to the slightest force, however great the velocity of impulse may be. On the other hand, supposethat a large bird, in full flight, can make forty miles per hour, or3, 520 feet per minute, and performs one stroke per second. Now, duringevery fractional portion of that stroke, the wing is acting upon andobtaining an impulse from a fresh and undisturbed body of air; and ifthe vibration of the wing is limited to an arc of two feet, this by nomeans represents the small force of action that would be obtained whenin a stationary position, for the impulse is secured upon a stratum offifty-eight feet in length of air at each stroke. So that the conditionsof weight of air for obtaining support equally well apply to weight ofair and its reaction in producing forward impulse. 'So necessary is the acquirement of this horizontal speed, even incommencing flight, that most heavy birds, when possible, rise againstthe wind, and even run at the top of their speed to make their wingsavailable, as in the example of the eagle, mentioned at the commencementof this paper. It is stated that the Arabs, on horseback, can approachnear enough to spear these birds, when on the plain, before they areable to rise; their habit is to perch on an eminence, where possible. 'The tail of a bird is not necessary for flight. A pigeon can flyperfectly with this appendage cut short off; it probably performs animportant function in steering, for it is to be remarked, that mostbirds that have either to pursue or evade pursuit are amply providedwith this organ. 'The foregoing reasoning is based upon facts, which tend to show thatthe flight of the largest and heaviest of all birds is really performedwith but a small amount of force, and that man is endowed withsufficient muscular power to enable him also to take individual andextended flights, and that success is probably only involved in aquestion of suitable mechanical adaptations. But if the wings are to bemodelled in imitation of natural examples, but very little considerationwill serve to demonstrate its utter impracticability when applied inthese forms. ' Thus Wenham, one of the best theorists of his age. The Society withwhich this paper connects his name has done work, between that time andthe present, of which the importance cannot be overestimated, and hasbeen of the greatest value in the development of aeronautics, both intheory and experiment. The objects of the Society are to give a strongerimpulse to the scientific study of aerial navigation, to promote theintercourse of those interested in the subject at home and abroad, andto give advice and instruction to those who study the principles uponwhich aeronautical science is based. From the date of its foundation theSociety has given special study to dynamic flight, putting this beforeballooning. Its library, its bureau of advice and information, and itsmeetings, all assist in forwarding the study of aeronautics, and itstwenty-three early Annual Reports are of considerable value, containingas they do a large amount of useful information on aeronauticalsubjects, and forming practically the basis of aeronautical science. Ante to Wenham, Stringfellow and the French experimenters already noted, by some years, was Le Bris, a French sea captain, who appears to haverequired only a thorough scientific training to have rendered him ofequal moment in the history of gliding flight with Lilienthal himself. Le Bris, it appears, watched the albatross and deduced, from the mannerin which it supported itself in the air, that plane surfaces couldbe constructed and arranged to support a man in like manner. OctaveChanute, himself a leading exponent of gliding, gives the bestdescription of Le Bris's experiments in a work, Progress in FlyingMachines, which, although published as recently as I 1894, is alreadyrare. Chanute draws from a still rarer book, namely, De la Landelle'swork published in 1884. Le Bris himself, quoted by De la Landelle asspeaking of his first visioning of human flight, describes how he killedan albatross, and then--'I took the wing of the albatross and exposedit to the breeze; and lo! in spite of me it drew forward into the wind;notwithstanding my resistance it tended to rise. Thus I had discoveredthe secret of the bird! I comprehended the whole mystery of flight. ' This apparently took place while at sea; later on Le Bris, returning toFrance, designed and constructed an artificial albatross of sufficientsize to bear his own weight. The fact that he followed the bird outlineas closely as he did attests his lack of scientific training for histask, while at the same time the success of the experiment was proof ofhis genius. The body of his artificial bird, boat-shaped, was 13 1/2 ft. In length, with a breadth of 4 ft. At the widest part. The materialwas cloth stretched over a wooden framework; in front was a small mastrigged after the manner of a ship's masts to which were attached polesand cords with which Le Bris intended to work the wings. Each wing was23 ft. In length, giving a total supporting surface of nearly 220 sq. Ft. ; the weight of the whole apparatus was only 92 pounds. For steering, both vertical and horizontal, a hinged tail was provided, and theleading edge of each wing was made flexible. In construction throughout, and especially in that of the wings, Le Bris adhered as closely aspossible to the original albatross. He designed an ingenious kind of mechanism which he termed 'Rotules, 'which by means of two levers gave a rotary motion to the front edge ofthe wings, and also permitted of their adjustment to various angles. The inventor's idea was to stand upright in the body of the contrivance, working the levers and cords with his hands, and with his feet ona pedal by means of which the steering tail was to be worked. Heanticipated that, given a strong wind, he could rise into the air afterthe manner of an albatross, without any need for flapping his wings, andthe account of his first experiment forms one of the most interestingincidents in the history of flight. It is related in full in Chanute'swork, from which the present account is summarised. Le Bris made his first experiment on a main road near Douarnenez, atTrefeuntec. From his observation of the albatross Le Bris concludedthat it was necessary to get some initial velocity in order to make themachine rise; consequently on a Sunday morning, with a breeze of about12 miles an hour blowing down the road, he had his albatross placed on acart and set off, with a peasant driver, against the wind. At the outsetthe machine was fastened to the cart by a rope running through the railson which the machine rested, and secured by a slip knot on Le Bris's ownwrist, so that only a jerk on his part was necessary to loosen the ropeand set the machine free. On each side walked an assistant holding thewings, and when a turn of the road brought the machine full into thewind these men were instructed to let go, while the driver increased thepace from a walk to a trot. Le Bris, by pressure on the levers of themachine, raised the front edges of his wings slightly; they took thewind almost instantly to such an extent that the horse, relieved of agreat part of the weight he had been drawing, turned his trot into agallop. Le Bris gave the jerk of the rope that should have unfastenedthe slip knot, but a concealed nail on the cart caught the rope, so thatit failed to run. The lift of the machine was such, however, that itrelieved the horse of very nearly the weight of the cart and driver, aswell as that of Le Bris and his machine, and in the end the rails of thecart gave way. Le Bris rose in the air, the machine maintaining perfectbalance and rising to a height of nearly 300 ft. , the total length ofthe glide being upwards of an eighth of a mile. But at the last momentthe rope which had originally fastened the machine to the cart got woundround the driver's body, so that this unfortunate dangled in the airunder Le Bris and probably assisted in maintaining the balance of theartificial albatross. Le Bris, congratulating himself on his success, was prepared to enjoy just as long a time in the air as the pressure ofthe wind would permit, but the howls of the unfortunate driver at theend of the rope beneath him dispelled his dreams; by working his levershe altered the angle of the front wing edges so skilfully as to make avery successful landing indeed for the driver, who, entirely uninjured, disentangled himself from the rope as soon as he touched the ground, andran off to retrieve his horse and cart. Apparently his release made a difference in the centre of gravity, forLe Bris could not manipulate his levers for further ascent; by skilfulmanipulation he retarded the descent sufficiently to escape injury tohimself; the machine descended at an angle, so that one wing, strikingthe ground in front of the other, received a certain amount of damage. It may have been on account of the reluctance of this same or anotherdriver that Le Bris chose a different method of launching himself inmaking a second experiment with his albatross. He chose the edge of aquarry which had been excavated in a depression of the ground; here heassembled his apparatus at the bottom of the quarry, and by means of arope was hoisted to a height of nearly 100 ft. From the quarry bottom, this rope being attached to a mast which he had erected upon the edgeof the depression in which the quarry was situated. Thus hoisted, thealbatross was swung to face a strong breeze that blew inland, and LeBris manipulated his levers to give the front edges of his wings adownward angle, so that only the top surfaces should take the wingpressure. Having got his balance, he obtained a lifting angle ofincidence on the wings by means of his levers, and released the hookthat secured the machine, gliding off over the quarry. On the glide hemet with the inevitable upward current of air that the quarry and thedepression in which it was situated caused; this current upset thebalance of the machine and flung it to the bottom of the quarry, breaking it to fragments. Le Bris, apparently as intrepid as ingenious, gripped the mast from which his levers were worked, and, springingupward as the machine touched earth, escaped with no more damage than abroken leg. But for the rebound of the levers he would have escaped eventhis. The interest of these experiments is enhanced by the fact that Le Briswas a seafaring man who conducted them from love of the science whichhad fired his imagination, and in so doing exhausted his own smallmeans. It was in 1855 that he made these initial attempts, andtwelve years passed before his persistence was rewarded by a publicsubscription made at Brest for the purpose of enabling him to continuehis experiments. He built a second albatross, and on the advice of hisfriends ballasted it for flight instead of travelling in it himself. Itwas not so successful as the first, probably owing to the lack of humancontrol while in flight; on one of the trials a height of 150 ft. Wasattained, the glider being secured by a thin rope and held so as to faceinto the wind. A glide of nearly an eighth of a mile was made with therope hanging slack, and, at the end of this distance, a rise in theground modified the force of the wind, whereupon the machine settleddown without damage. A further trial in a gusty wind resulted in thecomplete destruction of this second machine; Le Bris had no morefunds, no further subscriptions were likely to materialise, and sothe experiments of this first exponent of the art of gliding (savefor Besnier and his kind) came to an end. They constituted a notableachievement, and undoubtedly Le Bris deserves a better place than hasbeen accorded him in the ranks of the early experimenters. Contemporary with him was Charles Spencer, the first man to practicegliding in England. His apparatus consisted of a pair of wings with atotal area of 30 sq. Ft. , to which a tail and body were attached. Theweight of this apparatus was some 24 lbs. , and, launching himself onit from a small eminence, as was done later by Lilienthal in hisexperiments, the inventor made flights of over 120 feet. The glider inquestion was exhibited at the Aeronautical Exhibition of 1868. VI. THE AGE OF THE GIANTS Until the Wright Brothers definitely solved the problem of flight andvirtually gave the aeroplane its present place in aeronautics, therewere three definite schools of experiment. The first of these wasthat which sought to imitate nature by means of the ornithopter orflapping-wing machines directly imitative of bird flight; the secondschool was that which believed in the helicopter or lifting screw; thethird and eventually successful school is that which followed up theprinciple enunciated by Cayley, that of opposing a plane surface to theresistance of the air by supplying suitable motive power to drive it atthe requisite angle for support. Engineering problems generally go to prove that too close an imitationof nature in her forms of recipro-cating motion is not advantageous; itis impossible to copy the minutiae of a bird's wing effectively, and thebird in flight depends on the tiniest details of its feathers just asmuch as on the general principle on which the whole wing is constructed. Bird flight, however, has attracted many experimenters, including evenLilienthal; among others may be mentioned F. W. Brearey, who inventedwhat he called the 'Pectoral cord, ' which stored energy on each upstrokeof the artificial wing; E. P. Frost; Major R. Moore, and especiallyHureau de Villeneuve, a most enthusiastic student of this form offlight, who began his experiments about 1865, and altogether designedand made nearly 300 artificial birds, one of his later constructionswas a machine in bird form with a wing span of about 50 ft. ; themotive power for this was supplied by steam from a boiler which, beingstationary on the ground, was connected by a length of hose to themachine. De Villeneuve, turning on steam for his first trial, obtainedsufficient power to make the wings beat very forcibly; with the inventoron the machine the latter rose several feet into the air, whereupon deVilleneuve grew nervous and turned off the steam supply. The machinefell to the earth, breaking one of its wings, and it does not appearthat de Villeneuve troubled to reconstruct it. This experiment remainsas the greatest success yet achieved by any machine constructed on theornithopter principle. It may be that, as forecasted by the prophet Wells, the flapping-wingmachine will yet come to its own and compete with the aeroplane inefficiency. Against this, however, are the practical advantages ofthe rotary mechanism of the aeroplane propeller as compared with themovement of a bird's wing, which, according to Marey, moves in a figureof eight. The force derived from a propeller is of necessity continual, while it is equally obvious that that derived from a flapping movementis intermittent, and, in the recovery of a wing after completion of onestroke for the next, there is necessarily a certain cessation, if notloss, of power. The matter of experiment along any lines in connection with aviation isprimarily one of hard cash. Throughout the whole history of flight up tothe outbreak of the European war development has been handicapped onthe score of finance, and, since the arrival of the aeroplane, bothornithopter and helicopter schools have been handicapped by thisconsideration. Thus serious study of the efficiency of wings inimitation of those of the living bird has not been carried to a pointthat might win success for this method of propulsion. Even Wilbur Wrightstudied this subject and propounded certain theories, while a later andpossibly more scientific student, F. W. Lanchester, has also contributedempirical conclusions. Another and earlier student was LawrenceHargrave, who made a wing-propelled model which achieved successfulflight, and in 1885 was exhibited before the Royal Society of New SouthWales. Hargrave called the principle on which his propeller worked thatof a 'Trochoided plane'; it was, in effect, similar to the feathering ofan oar. Hargrave, to diverge for a brief while from the machine to the man, was one who, although he achieved nothing worthy of special remark, contributed a great deal of painstaking work to the science of flight. He made a series of experiments with man-lifting kites in addition tomaking a study of flapping-wing flight. It cannot be said that he setforth any new principle; his work was mainly imitative, but at the sametime by developing ideas originated in great measure by others he helpedtoward the solution of the problem. Attempts at flight on the helicopter principle consist in the work of Dela Landelle and others already mentioned. The possibility of flight bythis method is modified by a very definite disadvantage of which loversof the helicopter seem to take little account. It is always claimed fora machine of this type that it possesses great advantages both in risingand in landing, since, if it were effective, it would obviously be ableto rise from and alight on any ground capable of containing its ownbulk; a further advantage claimed is that the helicopter would be ableto remain stationary in the air, maintaining itself in any position bythe vertical lift of its propeller. These potential assets do not take into consideration the fact thatefficiency is required not only in rising, landing, and remainingstationary in the air, but also in actual flight. It must be evidentthat if a certain amount of the motive force is used in maintaining themachine off the ground, that amount of force is missing from the totalof horizontal driving power. Again, it is often assumed by advocates ofthis form of flight that the rapidity of climb of the helicopter wouldbe far greater than that of the driven plane; this view overlooks thefact that the maintenance of aerodynamic support would claim the greaterpart of the engine-power; the rate of ascent would be governed by theamount of power that could be developed surplus to that required formaintenance. This is best explained by actual figures: assuming that a propeller 15ft. In diameter is used, almost 50 horse-power would be required toget an upward lift of 1, 000 pounds; this amount of horse-power would becontinually absorbed in maintaining the machine in the air at any givenlevel; for actual lift from one level to another at a speed of elevenfeet per second a further 20 horse-power would be required, which meansthat 70 horse-power must be constantly provided for; this absorptionof power in the mere maintenance of aero-dynamic support is a permanentdrawback. The attraction of the helicopter lies, probably, in the ease with whichflight is demonstrated by means of models constructed on this principle, but one truism with regard to the principles of flight is that theproblems change remarkably, and often unexpectedly, with the size ofthe machine constructed for experiment. Berriman, in a brief but veryinteresting manual entitled Principles of Flight, assumed that 'there isa significant dimension of which the effective area is an expressionof the second power, while the weight became an expression of the thirdpower. Then once again we have the two-thirds power law militatingagainst the successful construction of large helicopters, on the groundthat the essential weight increases disproportionately fast to theeffective area. From a consideration of the structural features ofpropellers it is evident that this particular relationship does notapply in practice, but it seems reasonable that some such governingfactor should exist as an explanation of the apparent failure of allfull-sized machines that have been constructed. Among models there isnothing more strikingly successful than the toy helicopter, in which theessential weight is so small compared with the effective area. ' De la Landelle's work, already mentioned, was carried on a few yearslater by another Frenchman, Castel, who constructed a machine with eightpropellers arranged in two fours and driven by a compressed air motor orengine. The model with which Castel experimented had a total weight ofonly 49 lbs. ; it rose in the air and smashed itself by driving againsta wall, and the inventor does not seem to have proceeded further. Contemporary with Castel was Professor Forlanini, whose design was fora machine very similar to de la Landelle's, with two superposed screws. This machine ranks as the second on the helicopter principle to achieveflight; it remained in the air for no less than the third of a minute inone of its trials. Later experimenters in this direction were Kress, a German; ProfessorWellner, an Austrian; and W. R. Kimball, an American. Kress, like mostGermans, set to the development of an idea which others had originated;he followed de la Landelle and Forlanini by fitting two superposedpropellers revolving in opposite directions, and with this machine heachieved good results as regards horse-power to weight; Kimball, itappears, did not get beyond the rubber-driven model stage, and anysuccess he may have achieved was modified by the theory enunciated byBerriman and quoted above. Comparing these two schools of thought, the helicopter and bird-flightschools, it appears that the latter has the greater chance of eventualsuccess--that is, if either should ever come into competition with theaeroplane as effective means of flight. So far, the aeroplane holdsthe field, but the whole science of flight is so new and so full ofunexpected developments that this is no reason for assuming that othermeans may not give equal effect, when money and brains are diverted fromthe driven plane to a closer imitation of natural flight. Reverting from non-success to success, from consideration of the twomethods mentioned above to the direction in which practical flighthas been achieved, it is to be noted that between the time of LeBris, Stringfellow, and their contemporaries, and the nineties of lastcentury, there was much plodding work carried out with little visibleresult, more especially so far as English students were concerned. Amongthe incidents of those years is one of the most pathetic tragedies inthe whole history of aviation, that of Alphonse Penaud, who, in histhirty years of life, condensed the experience of his predecessors andcombined it with his own genius to state in a published patent whatthe aeroplane of to-day should be. Consider the following abstract ofPenaud's design as published in his patent of 1876, and comparison ofthis with the aeroplane that now exists will show very few divergencesexcept for those forced on the inventor by the fact that the internalcombustion engine had not then developed. The double surfaced planeswere to be built with wooden ribs and arranged with a slight dihedralangle; there was to be a large aspect ratio and the wings were camberedas in Stringfellow's later models. Provision was made for warping thewings while in flight, and the trailing edges were so designed as tobe capable of upward twist while the machine was in the air. The planeswere to be placed above the car, and provision was even made for a glasswind-screen to give protection to the pilot during flight. Steering wasto be accomplished by means of lateral and vertical planes forminga tail; these controlled by a single lever corresponding to the 'joystick' of the present day plane. Penaud conceived this machine as driven by two propellers; alternativelythese could be driven by petrol or steam-fed motor, and the centre ofgravity of the machine while in flight was in the front fifth of thewings. Penaud estimated from 20 to 30 horse-power sufficient to drivethis machine, weighing with pilot and passenger 2, 600 lbs. , through theair at a speed of 60 miles an hour, with the wings set at an angleof incidence of two degrees. So complete was the design that it evenincluded instruments, consisting of an aneroid, pressure indicator, ananemometer, a compass, and a level. There, with few alterations, is theaeroplane as we know it--and Penaud was twenty-seven when his patent waspublished. For three years longer he worked, experimenting with models, contributing essays and other valuable data to French papers on thesubject of aeronautics. His gains were ill health, poverty, and neglect, and at the age of thirty a pistol shot put an end to what had promisedto be one of the most brilliant careers in all the history of flight. Two years before the publication of Penaud's patent Thomas Moyexperimented at the Crystal Palace with a twin-propelled aeroplane, steam driven, which seems to have failed mainly because the internalcombustion engine had not yet come to give sufficient power for weight. Moy anchored his machine to a pole running on a prepared circular track;his engine weighed 80 lbs. And, developing only three horse-power, gavehim a speed of 12 miles an hour. He himself estimated that the machinewould not rise until he could get a speed of 35 miles an hour, and hisestimate was correct. Two six-bladed propellers were placed side by sidebetween the two main planes of the machine, which was supported on atriangular wheeled undercarriage and steered by fairly conventional tailplanes. Moy realised that he could not get sufficient power to achieveflight, but he went on experimenting in various directions, and leftmuch data concerning his experiments which has not yet been deemedworthy of publication, but which still contains a mass of informationthat is of practical utility, embodying as it does a vast amount ofpainstaking work. Penaud and Moy were followed by Goupil, a Frenchman, who, in place ofattempting to fit a motor to an aeroplane, experimented by making thewind his motor. He anchored his machine to the ground, allowing it twofeet of lift, and merely waited for a wind to come along and lift it. The machine was stream lined, and the wings, curving as in the earlyGerman patterns of war aeroplanes, gave a total lifting surface of about290 sq. Ft. Anchored to the ground and facing a wind of 19 feet persecond, Goupil's machine lifted its own weight and that of two men aswell to the limit of its anchorage. Although this took place as lateas 1883 the inventor went no further in practical work. He published abook, however, entitled La Locomotion Aerienne, which is still of greatimportance, more especially on the subject of inherent stability. In 1884 came the first patents of Horatio Phillips, whose work laymainly in the direction of investigation into the curvature of planesurfaces, with a view to obtaining the greatest amount of support. Phillips was one of the first to treat the problem of curvature ofplanes as a matter for scientific experiment, and, great as has been thedevelopment of the driven plane in the 36 years that have passed sincehe began, there is still room for investigation into the subject whichhe studied so persistently and with such valuable result. At this point it may be noted that, with the solitary exception ofLe Bris, practically every student of flight had so far set aboutconstructing the means of launching humanity into the air without anyattempt at ascertaining the nature and peculiarities of the sustainingmedium. The attitude of experimenters in general might be compared tothat of a man who from boyhood had grown up away from open water, and, at the first sight of an expanse of water, set to work to construct aboat with a vague idea that, since wood would float, only sufficientpower was required to make him an efficient navigator. Accident, perhaps, in the shape of lack of means of procuring driving power, droveLe Bris to the form of experiment which he actually carried out; itremained for the later years of the nineteenth century to produce menwho were content to ascertain the nature of the support the air wouldafford before attempting to drive themselves through it. Of the age in which these men lived and worked, giving their all in manycases to the science they loved, even to life itself, it may be saidwith truth that 'there were giants on the earth in those days, ' as faras aeronautics is in question. It was an age of giants who lived anddared and died, venturing into uncharted space, knowing nothing of itsdangers, giving, as a man gives to his mistress, without stint andfor the joy of the giving. The science of to-day, compared with theglimmerings that were in that age of the giants, is a fixed and certainthing; the problems of to-day are minor problems, for the great majorproblem vanished in solution when the Wright Brothers made their firstascent. In that age of the giants was evolved the flying man, the newtype in human species which found full expression and came to fulldevelopment in the days of the war, achieving feats of daring andendurance which leave the commonplace landsman staggered at thought ofthat of which his fellows prove themselves capable. He is a new type, this flying man, a being of self-forgetfulness; of such was Lilienthal, of such was Pilcher; of such in later days were Farman, Bleriot, Hamel, Rolls, and their fellows; great names that will live for as long as manflies, adventurers equally with those of the spacious days of Elizabeth. To each of these came the call, and he worked and dared and passed, having, perhaps, advanced one little step in the long march that has ledtoward the perfecting of flight. It is not yet twenty years since man first flew, but into that twentyyears have been compressed a century or so of progress, while, in thetwo decades that preceded it, was compressed still more. We have only torecall and recount the work of four men: Lilienthal, Langley, Pilcher, and Clement Ader to see the immense stride that was made between thetime when Penaud pulled a trigger for the last time and the WrightBrothers first left the earth. Into those two decades was compressed theinvestigation that meant knowledge of the qualities of the air, togetherwith the development of the one prime mover that rendered flight apossibility--the internal combustion engine. The coming and progress ofthis latter is a thing apart, to be detailed separately; for the presentwe are concerned with the evolution of the driven plane, and with it theevolution of that daring being, the flying man. The two are inseparable, for the men gave themselves to their art; the story of Lilienthal's lifeand death is the story of his work; the story of Pilcher's work is thatof his life and death. Considering the flying man as he appeared in the war period, thereentered into his composition a new element--patriotism--which broughtabout a modification of the type, or, perhaps, made it appear thatcertain men belonged to the type who in reality were commonplacemortals, animated, under normal conditions, by normal motives, butdriven by the stress of the time to take rank with the last expressionof human energy, the flying type. However that may be, what may betermed the mathematising of aeronautics has rendered the type itselfevanescent; your pilot of to-day knows his craft, once he is trained, much in the manner that a driver of a motor-lorry knows his vehicle;design has been systematised, capabilities have been tabulated; camber, dihedral angle, aspect ratio, engine power, and plane surface, arebusiness items of drawing office and machine shop; there is room forenterprise, for genius, and for skill; once and again there is room fordaring, as in the first Atlantic flight. Yet that again was a thing ofmathematical calculation and petrol storage, allied to a certain starkcourage which may be found even in landsmen. For the ventures into theunknown, the limit of daring, the work for work's sake, with the almostcertainty that the final reward was death, we must look back to the ageof the giants, the age when flying was not a business, but romance. VII. LILIENTHAL AND PILCHER There was never a more enthusiastic and consistent student of theproblems of flight than Otto Lilienthal, who was born in 1848 at Anklam, Pomerania, and even from his early school-days dreamed and planned theconquest of the air. His practical experiments began when, at the ageof thirteen, he and his brother Gustav made wings consisting of woodenframework covered with linen, which Otto attached to his arms, and thenran downhill flapping them. In consequence of possible derision on thepart of other boys, Otto confined these experiments for the most part tomoonlit nights, and gained from them some idea of the resistance offeredby flat surfaces to the air. It was in 1867 that the two brothersbegan really practical work, experimenting with wings which, fromtheir design, indicate some knowledge of Besnier and the history of hisgliding experiments; these wings the brothers fastened to their backs, moving them with their legs after the fashion of one attempting to swim. Before they had achieved any real success in gliding the Franco-Germanwar came as an interruption; both brothers served in this campaign, resuming their experiments in 1871 at the conclusion of hostilities. The experiments made by the brothers previous to the war had convincedOtto that previous experimenters in gliding flight had failed throughreliance on empirical conclusions or else through incomplete observationon their own part, mostly of bird flight. From 1871 onward OttoLilenthal (Gustav's interest in the problem was not maintained as washis brother's) made what is probably the most detailed and accurateseries of observations that has ever been made with regard to theproperties of curved wing surfaces. So far as could be done, Lilienthaltabulated the amount of air resistance offered to a bird's wing, ascertaining that the curve is necessary to flight, as offering far moreresistance than a flat surface. Cayley, and others, had already statedthis, but to Lilienthal belongs the honour of being first to put thestatement to effective proof--he made over 2, 000 gliding flightsbetween 1891 and the regrettable end of his experiments; his practicalconclusions are still regarded as part of the accepted theory ofstudents of flight. In 1889 he published a work on the subject ofgliding flight which stands as data for investigators, and, on theconclusions embodied in this work, he began to build his gliders andpractice what he had preached, turning from experiment with models towings that he could use. It was in the summer of 1891 that he built his first glider of rods ofpeeled willow, over which was stretched strong cotton fabric; with this, which had a supporting surface of about 100 square feet, Otto Lilienthallaunched himself in the air from a spring board, making glides which, atfirst of only a few feet, gradually lengthened. As his experience ofthe supporting qualities of the air progressed he gradually alteredhis designs until, when Pilcher visited him in the spring of 1895, he experimented with a glider, roughly made of peeled willow rods andcotton fabric, having an area of 150 square feet and weighing half ahundredweight. By this time Lilienthal had moved from his springboard toa conical artificial hill which he had had thrown up on level ground atGrosse Lichterfelde, near Berlin. This hill was made with earth takenfrom the excavations incurred in constructing a canal, and had a caveinside in which Lilienthal stored his machines. Pilcher, in his paperon 'Gliding, ' [*] gives an excellent short summary of Lilienthal'sexperiments, from which the following extracts are taken:-- [*] Aeronautical Classes, No. 5. Royal Aeronautical Society'spublications. 'At first Lilienthal used to experiment by jumping off a springboardwith a good run. Then he took to practicing on some hills close toBerlin. In the summer of 1892 he built a flat-roofed hut on the summitof a hill, from the top of which he used to jump, trying, of course, tosoar as far as possible before landing.... One of the great dangers witha soaring machine is losing forward speed, inclining the machine toomuch down in front, and coming down head first. Lilienthal was thefirst to introduce the system of handling a machine in the air merelyby moving his weight about in the machine; he always rested only on hiselbows or on his elbows and shoulders.... 'In 1892 a canal was being cut, close to where Lilienthal lived, in thesuburbs of Berlin, and with the surplus earth Lilienthal had a specialhill thrown up to fly from. The country round is as flat as the sea, andthere is not a house or tree near it to make the wind unsteady, sothis was an ideal practicing ground; for practicing on natural hillsis generally rendered very difficult by shifty and gusty winds.... Thishill is 50 feet high, and conical. Inside the hill there is a cave forthe machines to be kept in.... When Lilienthal made a good flight heused to land 300 feet from the centre of the hill, having come down atan angle of 1 in 6; but his best flights have been at an angle of about1 in 10. 'If it is calm, one must run a few steps down the hill, holding themachine as far back on oneself as possible, when the air will graduallysupport one, and one slides off the hill into the air. If there is anywind, one should face it at starting; to try to start with a side windis most unpleasant. It is possible after a great deal of practice toturn in the air, and fairly quickly. This is accomplished by throwingone's weight to one side, and thus lowering the machine on that sidetowards which one wants to turn. Birds do the same thing--crows andgulls show it very clearly. Last year Lilienthal chiefly experimentedwith double-surfaced machines. These were very much like the oldmachines with awnings spread above them. 'The object of making these double-surfaced machines was to get moresurface without increasing the length and width of the machine. This, of course, it does, but I personally object to any machine in whichthe wing surface is high above the weight. I consider that it makesthe machine very difficult to handle in bad weather, as a puff of windstriking the surface, high above one, has a great tendency to heel themachine over. 'Herr Lilienthal kindly allowed me to sail down his hill in one of thesedouble-surfaced machines last June. With the great facility afforded byhis conical hill the machine was handy enough; but I am afraid I shouldnot be able to manage one at all in the squally districts I have had topractice in over here. 'Herr Lilienthal came to grief through deserting his old method ofbalancing. In order to control his tipping movements more rapidly heattached a line from his horizontal rudder to his head, so that when hemoved his head forward it would lift the rudder and tip the machine upin front, and vice versa. He was practicing this on some natural hillsoutside Berlin, and he apparently got muddled with the two motions, and, in trying to regain speed after he had, through a lull in the wind, cometo rest in the air, let the machine get too far down in front, came downhead first and was killed. ' Then in another passage Pilcher enunciates what is the true value ofsuch experiments as Lilienthal--and, subsequently, he himself--made:'The object of experimenting with soaring machines, ' he says, 'is toenable one to have practice in starting and alighting and controlling amachine in the air. They cannot possibly float horizontally in theair for any length of time, but to keep going must necessarily lose inelevation. They are excellent schooling machines, and that is all theyare meant to be, until power, in the shape of an engine working a screwpropeller, or an engine working wings to drive the machine forward, isadded; then a person who is used to soaring down a hill with a simplesoaring machine will be able to fly with comparative safety. One canbest compare them to bicycles having no cranks, but on which one couldlearn to balance by coming down an incline. ' It was in 1895 that Lilienthal passed from experiment with the monoplanetype of glider to the construction of a biplane glider which, accordingto his own account, gave better results than his previous machines. 'Six or seven metres velocity of wind, ' he says, 'sufficed to enablethe sailing surface of 18 square metres to carry me almost horizontallyagainst the wind from the top of my hill without any starting jump. Ifthe wind is stronger I allow myself to be simply lifted from the pointof the hill and to sail slowly towards the wind. The direction of theflight has, with strong wind, a strong upwards tendency. I often reachpositions in the air which are much higher than my starting point. Atthe climax of such a line of flight I sometimes come to a standstillfor some time, so that I am enabled while floating to speak with thegentlemen who wish to photograph me, regarding the best position for thephotographing. ' Lilienthal's work did not end with simple gliding, though he did notlive to achieve machine-driven flight. Having, as he considered, gainedsufficient experience with gliders, he constructed a power-drivenmachine which weighed altogether about 90 lbs. , and this was thoroughlytested. The extremities of its wings were made to flap, and the drivingpower was obtained from a cylinder of compressed carbonic acid gas, released through a hand-operated valve which, Lilienthal anticipated, would keep the machine in the air for four minutes. There were certainminor accidents to the mechanism, which delayed the trial flights, andon the day that Lilienthal had determined to make his trial he made along gliding flight with a view to testing a new form of rudder that--asPilcher relates--was worked by movements of his head. His death cameabout through the causes that Pilcher states; he fell from a height of50 feet, breaking his spine, and the next day he died. It may be said that Lilienthal accomplished as much as any one of thegreat pioneers of flying. As brilliant in his conceptions as da Vincihad been in his, and as conscientious a worker as Borelli, he laid thefoundations on which Pilcher, Chanute, and Professor Montgomery wereable to build to such good purpose. His book on bird flight, publishedin 1889, with the authorship credited both to Otto and his brotherGustav, is regarded as epoch-making; his gliding experiments are no lessentitled to this description. In England Lilienthal's work was carried on by Percy Sinclair Pilcher, who, born in 1866, completed six years' service in the British Navyby the time that he was nineteen, and then went through a course ofengineering, subsequently joining Maxim in his experimental work. It wasnot until 1895 that he began to build the first of the series of gliderswith which he earned his plane among the pioneers of flight. Probablythe best account of Pilcher's work is that given in the AeronauticalClassics issued by the Royal Aeronautical Society, from which thefollowing account of Pilcher's work is mainly abstracted. [*] [*] Aeronautical Classes, No. 5. Royal Aeronautical Societypublications. The 'Bat, ' as Pilcher named his first glider, was a monoplane which hecompleted before he paid his visit to Lilienthal in 1895. Concerningthis Pilcher stated that he purposely finished his own machine beforegoing to see Lilienthal, so as to get the greatest advantage from anyoriginal ideas he might have; he was not able to make any trials withthis machine, however, until after witnessing Lilienthal's experimentsand making several glides in the biplane glider which Lilienthalconstructed. The wings of the 'Bat' formed a pronounced dihedral angle; the tipsbeing raised 4 feet above the body. The spars forming the enteringedges of the wings crossed each other in the centre and were lashed toopposite sides of the triangle that served as a mast for the stay-wiresthat guyed the wings. The four ribs of each wing, enclosed in pocketsin the fabric, radiated fanwise from the centre, and were each stayed bythree steel piano-wires to the top of the triangular mast, and similarlyto its base. These ribs were bolted down to the triangle at their roots, and could be easily folded back on to the body when the glider was notin use. A small fixed vertical surface was carried in the rear. Theframework and ribs were made entirely of Riga pine; the surface fabricwas nainsook. The area of the machine was 150 square feet; its weight45 lbs. ; so that in flight, with Pilcher's weight of 145 lbs. Added, itcarried one and a half pounds to the square foot. Pilcher's first glides, which he carried out on a grass hill on thebanks of the Clyde near Cardross, gave little result, owing to theexaggerated dihedral angle of the wings, and the absence of a horizontaltail. The 'Bat 'was consequently reconstructed with a horizontal tailplane added to the vertical one, and with the wings lowered so that thetips were only six inches above the level of the body. The machine nowgave far better results; on the first glide into a head wind Pilcherrose to a height of twelve feet and remained in the the air for a thirdof a minute; in the second attempt a rope was used to tow the glider, which rose to twenty feet and did not come to earth again until nearlya minute had passed. With experience Pilcher was able to lengthen hisglide and improve his balance, but the dropped wing tips made landingdifficult, and there were many breakages. In consequence of this Pilcher built a second glider which he namedthe 'Beetle, ' because, as he said, it looked like one. In this thesquare-cut wings formed almost a continuous plane, rigidly fixed to thecentral body, which consisted of a shaped girder. These wings were builtup of five transverse bamboo spars, with two shaped ribs running fromfore to aft of each wing, and were stayed overhead to a couple of masts. The tail, consisting of two discs placed crosswise (the horizontalone alone being movable), was carried high up in the rear. With theexception of the wing-spars, the whole framework was built of whitepine. The wings in this machine were actually on a higher level than theoperator's head; the centre of gravity was, consequently, very low, afact which, according to Pilcher's own account, made the glider verydifficult to handle. Moreover, the weight of the 'Beetle, ' 80 lbs. , wasconsiderable; the body had been very solidly built to enable it to carrythe engine which Pilcher was then contemplating; so that the glidercarried some 225 lbs. With its area of 170 square feet--too great a massfor a single man to handle with comfort. It was in the spring of 1896 that Pilcher built his third glider, the'Gull, ' with 300 square feet of area and a weight of 55 lbs. The size ofthis machine rendered it unsuitable for experiment in any but very calmweather, and it incurred such damage when experiments were made in abreeze that Pilcher found it necessary to build a fourth, which he namedthe 'Hawk. ' This machine was very soundly built, being constructed ofbamboo, with the exception of the two main transverse beams. The wingswere attached to two vertical masts, 7 feet high, and 8 feet apart, joined at their summits and their centres by two wooden beams. Each winghad nine bamboo ribs, radiating from its mast, which was situated at adistance of 2 feet 6 inches from the forward edge of the wing. Each ribwas rigidly stayed at the top of the mast by three tie-wires, and by asimilar number to the bottom of the mast, by which means the curve ofeach wing was maintained uniformly. The tail was formed of a triangularhorizontal surface to which was affixed a triangular vertical surface, and was carried from the body on a high bamboo mast, which was alsostayed from the masts by means of steel wires, but only on its uppersurface, and it was the snapping of one of these guy wires which causedthe collapse of the tail support and brought about the fatal end ofPilcher's experiments. In flight, Pilcher's head, shoulders, and thegreater part of his chest projected above the wings. He took up hisposition by passing his head and shoulders through the top apertureformed between the two wings, and resting his forearms on thelongitudinal body members. A very simple form of undercarriage, whichtook the weight off the glider on the ground, was fitted, consisting oftwo bamboo rods with wheels suspended on steel springs. Balance and steering were effected, apart from the high degree ofinherent stability afforded by the tail, as in the case of Lilienthal'sglider, by altering the position of the body. With this machine Pilchermade some twelve glides at Eynsford in Kent in the summer of 1896, andas he progressed he increased the length of his glides, and also handledthe machine more easily, both in the air and in landing. He was occupiedwith plans for fitting an engine and propeller to the 'Hawk, ' but, inthese early days of the internal combustion engine, was unable toget one light enough for his purpose. There were rumours of an engineweighing 15 lbs. Which gave 1 horse-power, and was reported to be inexistence in America, but it could not be traced. In the spring of 1897 Pilcher took up his gliding experiments again, obtaining what was probably the best of his glides on June 19th, when healighted after a perfectly balanced glide of over 250 yards in length, having crossed a valley at a considerable height. From his variousexperiments he concluded that once the machine was launched in the airan engine of, at most, 3 horse-power would suffice for the maintenanceof horizontal flight, but he had to allow for the additional weightof the engine and propeller, and taking into account the comparativeinefficiency of the propeller, he planned for an engine of 4horse-power. Engine and propeller together were estimated at under 44lbs. Weight, the engine was to be fitted in front of the operator, andby means of an overhead shaft was to operate the propeller situatedin rear of the wings. 1898 went by while this engine was underconstruction. Then in 1899 Pilcher became interested in LawrenceHargrave's soaring kites, with which he carried out experiments duringthe summer of 1899. It is believed that he intended to incorporatea number of these kites in a new machine, a triplane, of which thefragments remaining are hardly sufficient to reconstitute the completeglider. This new machine was never given a trial. For on September 30th, 1899, at Stamford Hall, Market Harborough, Pilcher agreed to give ademonstration of gliding flight, but owing to the unfavourable weatherhe decided to postpone the trial of the new machine and to experimentwith the 'Hawk, ' which was intended to rise from a level field, towed bya line passing over a tackle drawn by two horses. At the first trial themachine rose easily, but the tow-line snapped when it was well clear ofthe ground, and the glider descended, weighed down through being soddenwith rain. Pilcher resolved on a second trial, in which the glider againrose easily to about thirty feet, when one of the guy wires of the tailbroke, and the tail collapsed; the machine fell to the ground, turningover, and Pilcher was unconscious when he was freed from the wreckage. Hopes were entertained of his recovery, but he died on Monday, October2nd, 1899, aged only thirty-four. His work in the cause of flyinglasted only four years, but in that time his actual accomplishments weresufficient to place his name beside that of Lilienthal, with whom heranks as one of the greatest exponents of gliding flight. VIII. AMERICAN GLIDING EXPERIMENTS While Pilcher was carrying on Lilienthal's work in England, the greatGerman had also a follower in America; one Octave Chanute, who, in oneof the statements which he has left on the subject of his experimentsacknowledges forty years' interest in the problem of flight, did moreto develop the glider in America than--with the possible exceptionof Montgomery--any other man. Chanute had all the practicality of anAmerican; he began his work, so far as actual gliding was concerned, with a full-sized glider of the Lilienthal type, just before Lilienthalwas killed. In a rather rare monograph, entitled Experiments in Flying, Chanute states that he found the Lilienthal glider hazardous and decidedto test the value of an idea of his own; in this he followed the samegeneral method, but reversed the principle upon which Lilienthal haddepended for maintaining his equilibrium in the air. Lilienthal hadshifted the weight of his body, under immovable wings, as fast and asfar as the sustaining pressure varied under his surfaces; this shiftingwas mainly done by moving the feet, as the actions required were smallexcept when alighting. Chanute's idea was to have the operator remainseated in the machine in the air, and to intervene only to steer or toalight; moving mechanism was provided to adjust the wings automaticallyin order to restore balance when necessary. Chanute realised that experiments with models were of little use; inorder to be fully instructive, these experiments should be made witha full-sized machine which carried its operator, for models seldom flytwice alike in the open air, and no relation can be gained from them ofthe divergent air currents which they have experienced. Chanute's ideawas that any flying machine which might be constructed must be able tooperate in a wind; hence the necessity for an operator to report uponwhat occurred in flight, and to acquire practical experience of the workof the human factor in imitation of bird flight. From this point ofview he conducted his own experiments; it must be noted that he wasover sixty years of age when he began, and, being no longer sufficientlyyoung and active to perform any but short and insignificant glides, thecourage of the man becomes all the more noteworthy; he set to work toevolve the state required by the problem of stability, and without anyexpectation of advancing to the construction of a flying machine whichmight be of commercial value. His main idea was the testing of devicesto secure equilibrium; for this purpose he employed assistants tocarry out the practical work, where he himself was unable to supply thenecessary physical energy. Together with his assistants he found a suitable place for experimentsamong the sandhills on the shore of Lake Michigan, about thirty mileseastward from Chicago. Here a hill about ninety-five feet high wasselected as a point from which Chanute's gliders could set off; inpractice, it was found that the best observation was to be obtainedfrom short glides at low speed, and, consequently, a hill which wasonly sixty-one feet above the shore of the lake was employed for theexperimental work done by the party. In the years 1896 and 1897, with parties of from four to six persons, five full-sized gliders were tried out, and from these two distincttypes were evolved: of these one was a machine consisting of five tiersof wings and a steering tail, and the other was of the biplane type;Chanute believed these to be safer than any other machine previouslyevolved, solving, as he states in his monograph, the problem of inherentequilibrium as fully as this could be done. Unfortunately, very fewphotographs were taken of the work in the first year, but one view of amultiple wing-glider survives, showing the machine in flight. In 1897 aseries of photographs was taken exhibiting the consecutive phases ofa single flight; this series of photographs represents the experiencegained in a total of about one thousand glides, but the point of viewwas varied so as to exhibit the consecutive phases of one single flight. The experience gained is best told in Chanute's own words. 'The firstthing, ' he says, 'which we discovered practically was that the windflowing up a hill-side is not a steadily-flowing current like that of ariver. It comes as a rolling mass, full of tumultuous whirls and eddies, like those issuing from a chimney; and they strike the apparatus withconstantly varying force and direction, sometimes withdrawing supportwhen most needed. It has long been known, through instrumentalobservations, that the wind is constantly changing in force anddirection; but it needed the experience of an operator afloat on agliding machine to realise that this all proceeded from cyclonic action;so that more was learned in this respect in a week than had previouslybeen acquired by several years of experiments with models. There was apair of eagles, living in the top of a dead tree about two miles fromour tent, that came almost daily to show us how such wind effects areovercome and utilised. The birds swept in circles overhead onpulseless wings, and rose high up in the air. Occasionally there wasa side-rocking motion, as of a ship rolling at sea, and then the birdsrocked back to an even keel; but although we thought the action wasclearly automatic, and were willing to learn, our teachers were toofar off to show us just how it was done, and we had to experiment forourselves. ' Chanute provided his multiple glider with a seat, but, since eachglide only occupied between eight and twelve seconds, there was littlepossibility of the operator seating himself. With the multiple glider apair of horizontal bars provided rest for the arms, and beyond thesewas a pair of vertical bars which the operator grasped with his hands;beyond this, the operator was in no way attached to the machine. Hetook, at the most, four running steps into the wind, which launchedhim in the air, and thereupon he sailed into the wind on a generallydescending course. In the matter of descent Chanute observed the sparrowand decided to imitate it. 'When the latter, ' he says, 'approaches thestreet, he throws his body back, tilts his outspread wings nearly squareto the course, and on the cushion of air thus encountered he stops hisspeed and drops lightly to the ground. So do all birds. We tried it withmisgivings, but found it perfectly effective. The soft sand was a greatadvantage, and even when the experts were racing there was not a singlesprained ankle. ' With the multiple winged glider some two to three hundred glides weremade without any accident either to the man or to the machine, and theaction was found so effective, the principle so sound, that full planswere published for the benefit of any experimenters who might wish toimprove on this apparatus. The American Aeronautical Annual for 1897contains these plans; Chanute confessed that some movement on the partof the operator was still required to control the machine, but it wasonly a seventh or a sixth part of the movement required for control ofthe Lilienthal type. Chanute waxed enthusiastic over the possibilities of gliding, concerningwhich he remarks that 'There is no more delightful sensation than thatof gliding through the air. All the faculties are on the alert, andthe motion is astonishingly smooth and elastic. The machine respondsinstantly to the slightest movement of the operator; the air rushes byone's ears; the trees and bushes flit away underneath, and the landingcomes all too quickly. Skating, sliding, and bicycling are not to becompared for a moment to aerial conveyance, in which, perhaps, zest isadded by the spice of danger. For it must be distinctly understood thatthere is constant danger in such preliminary experiments. When thishazard has been eliminated by further evolution, gliding will become amost popular sport. ' Later experiments proved that the biplane type of glider gave betterresults than the rather cumbrous model consisting of five tiers ofplanes. Longer and more numerous glides, to the number of seven to eighthundred, were obtained, the rate of descent being about one in six. Thelongest distance traversed was about 120 yards, but Chanute had dreamsof starting from a hill about 200 feet high, which would have given himgliding flights of 1, 200 feet. He remarked that 'In consequence ofthe speed gained by running, the initial stage of the flight is nearlyhorizontal, and it is thrilling to see the operator pass from thirty toforty feet overhead, steering his machine, undulating his course, andstruggling with the wind-gusts which whistle through the guy wires. Theautomatic mechanism restores the angle of advance when compromised byvariations of the breeze; but when these come from one side and tilt theapparatus, the weight has to be shifted to right the machine... Thesegusts sometimes raise the machine from ten to twenty feet vertically, and sometimes they strike the apparatus from above, causing it todescend suddenly. When sailing near the ground, these vicissitudes canbe counteracted by movements of the body from three to four inches; butthis has to be done instantly, for neither wings nor gravity will waiton meditation. At a height of three hundred or four hundred feet theregulating mechanism would probably take care of these wind-gusts, as itdoes, in fact, for their minor variations. The speed of the machineis generally about seventeen miles an hour over the ground, and fromtwenty-two to thirty miles an hour relative to the air. Constant effortwas directed to keep down the velocity, which was at times fifty-twomiles an hour. This is the purpose of the starting and gliding againstthe wind, which thus furnishes an initial velocity without there beingundue speed at the landing. The highest wind we dared to experiment inblew at thirty-one miles an hour; when the wind was stronger, we waitedand watched the birds. ' Chanute details an amusing little incident which occurred in the courseof experiment with the biplane glider. He says that 'We had taken oneof the machines to the top of the hill, and loaded its lower wings withsand to hold it while we e went to lunch. A gull came strolling inland, and flapped full-winged to inspect. He swept several circles above themachine, stretched his neck, gave a squawk and went off. Presently hereturned with eleven other gulls, and they seemed to hold a conclaveabout one hundred feet above the big new white bird which they haddiscovered on the sand. They circled round after round, and once in awhile there was a series of loud peeps, like those of a rusty gate, asif in conference, with sudden flutterings, as if a terrifying suggestionhad been made. The bolder birds occasionally swooped downwards toinspect the monster more closely; they twisted their heads around tobring first one eye and then the other to bear, and then they roseagain. After some seven or eight minutes of this performance, theyevidently concluded either that the stranger was too formidable totackle, if alive, or that he was not good to eat, if dead, and they flewoff to resume fishing, for the weak point about a bird is his stomach. ' The gliders were found so stable, more especially the biplane form, thatin the end Chanute permitted amateurs to make trials under guidance, and throughout the whole series of experiments not a single accidentoccurred. Chanute came to the conclusion that any young, quick, andhandy man could master a gliding machine almost as soon as he could getthe hang of a bicycle, although the penalty for any mistake would bemuch more severe. At the conclusion of his experiments he decided that neither themultiple plane nor the biplane type of glider was sufficiently perfectedfor the application of motive power. In spite of the amount of automaticstability that he had obtained he considered that there was yet more tobe done, and he therefore advised that every possible method of securingstability and safety should be tested, first with models, and then withfull-sized machines; designers, he said, should make a point of practicein order to make sure of the action, to proportion and adjust the partsof their machine, and to eliminate hidden defects. Experimentalflight, he suggested, should be tried over water, in order to break anyaccidental fall; when a series of experiments had proved the stabilityof a glider, it would then be time to apply motive power. He admittedthat such a process would be both costly and slow, but, he said, that'it greatly diminished the chance of those accidents which bring a wholeline of investigation into contempt. ' He saw the flying machine as whatit has, in fact, been; a child of evolution, carried on step by stepby one investigator after another, through the stages of doubt andperplexity which lie behind the realm of possibility, beyond which isthe present day stage of actual performance and promise of ultimatesuccess and triumph over the earlier, more cumbrous, and slower forms ofthe transport that we know. Chanute's monograph, from which the foregoing notes have been comprised, was written soon after the conclusion of his series of experiments. Hedoes not appear to have gone in for further practical work, but tohave studied the subject from a theoretical view-point and with greatattention to the work done by others. In a paper contributed in 1900to the American Independent, he remarks that 'Flying machines promisebetter results as to speed, but yet will be of limited commercialapplication. They may carry mails and reach other inaccessible places, but they cannot compete with railroads as carriers of passengers orfreight. They will not fill the heavens with commerce, abolish customhouses, or revolutionise the world, for they will be expensive forthe loads which they can carry, and subject to too many weathercontingencies. Success is, however, probable. Each experimenter hasadded something to previous knowledge which his successors can avail of. It now seems likely that two forms of flying machines, a sporting typeand an exploration type, will be gradually evolved within one or twogenerations, but the evolution will be costly and slow, and must becarried on by well-equipped and thoroughly informed scientific men; forthe casual inventor, who relies upon one or two happy inspirations, willhave no chance of success whatever. ' Follows Professor John J. Montgomery, who, in the true American spirit, describes his own experiments so well that nobody can possibly do itbetter. His account of his work was given first of all in the AmericanJournal, Aeronautics, in January, 1909, and thence transcribed in theEnglish paper of the same name in May, 1910, and that account is herecopied word for word. It may, however, be noted first that as far backas 1860, when Montgomery was only a boy, he was attracted to the studyof aeronautical problems, and in 1883 he built his first machine, which was of the flapping-wing ornithopter type, and which showed itsdesigner, with only one experiment, that he must design some otherform of machine if he wished to attain to a successful flight. Chanute details how, in 1884 and 1885 Montgomery built three gliders, demonstrating the value of curved surfaces. With the first of thesegliders Montgomery copied the wing of a seagull; with the second heproved that a flat surface was virtually useless, and with the thirdhe pivoted his wings as in the Antoinette type of power-propelledaeroplane, proving to his own satisfaction that success lay in thisdirection. His own account of the gliding flights carried out under hisdirection is here set forth, being the best description of his work thatcan be obtained:-- 'When I commenced practical demonstration in my work with aeroplanesI had before me three points; first, equilibrium; second, completecontrol; and third, long continued or soaring flight. In starting Iconstructed and tested three sets of models, each in advance of theother in regard to the continuance of their soaring powers, but allequally perfect as to equilibrium and control. These models were testedby dropping them from a cable stretched between two mountain tops, withvarious loads, adjustments and positions. And it made no differencewhether the models were dropped upside down or any other conceivableposition, they always found their equilibrium immediately and glidedsafely to earth. 'Then I constructed a large machine patterned after the first model, andwith the assistance of three cowboy friends personally made a number offlights in the steep mountains near San Juan (a hundred miles distant). In making these flights I simply took the aeroplane and made a runningjump. These tests were discontinued after I put my foot into a squirrelhole in landing and hurt my leg. 'The following year I commenced the work on a larger scale, by engagingaeronauts to ride my aeroplane dropped from balloons. During this work Iused five hot-air balloons and one gas balloon, five or six aeroplanes, three riders--Maloney, Wilkie, and Defolco--and had sixteen applicantson my list, and had a training station to prepare any when I neededthem. 'Exhibitions were given in Santa Cruz, San Jose, Santa Clara, Oaklands, and Sacramento. The flights that were made, instead of being haphazardaffairs, were in the order of safety and development. In the firstflight of an aeronaut the aeroplane was so arranged that the rider hadlittle liberty of action, consequently he could make only a limitedflight. In some of the first flights, the aeroplane did little more thansettle in the air. But as the rider gained experience in each successiveflight I changed the adjustments, giving him more liberty of action, sohe could obtain longer flights and more varied movements in the flights. But in none of the flights did I have the adjustments so that the ridershad full liberty, as I did not consider that they had the requisiteknowledge and experience necessary for their safety; and hence, noneof my aeroplanes were launched so arranged that the rider could makeadjustments necessary for a full flight. 'This line of action caused a good deal of trouble with aeronauts orriders, who had unbounded confidence and wanted to make long flightsafter the first few trials; but I found it necessary, as they seemedslow in comprehending the important elements and were willing totake risks. To give them the full knowledge in these matters I wasformulating plans for a large starting station on the Mount HamiltonRange from which I could launch an aeroplane capable of carrying two, one of my aeronauts and myself, so I could teach him by demonstration. But the disasters consequent on the great earthquake completely stoppedall my work on these lines. The flights that were given were only thefirst of the series with aeroplanes patterned after the first model. There were no aeroplanes constructed according to the two other models, as I had not given the full demonstration of the workings of the first, though some remarkable and startling work was done. On one occasionMaloney, in trying to make a very short turn in rapid flight, pressedvery hard on the stirrup which gives a screw-shape to the wings, andmade a side somersault. The course of the machine was very much like oneturn of a corkscrew. After this movement the machine continued on itsregular course. And afterwards Wilkie, not to be outdone by Maloney, told his friends he would do the same, and in a subsequent flight madetwo side somersaults, one in one direction and the other in an opposite, then made a deep dive and a long glide, and, when about three hundredfeet in the air, brought the aeroplane to a sudden stop and settled tothe earth. After these antics, I decreased the extent of the possiblechange in the form of wing-surface, so as to allow only straight sailingor only long curves in turning. 'During my work I had a few carping critics that I silenced by thisstanding offer: If they would deposit a thousand dollars I would coverit on this proposition. I would fasten a 150 pound sack of sand in therider's seat, make the necessary adjustments, and send up an aeroplaneupside down with a balloon, the aeroplane to be liberated by a timefuse. If the aeroplane did not immediately right itself, make a flight, and come safely to the ground, the money was theirs. 'Now a word in regard to the fatal accident. The circumstances arethese: The ascension was given to entertain a military company in whichwere many of Maloney's friends, and he had told them he would give themost sensational flight they ever heard of. As the balloon was risingwith the aeroplane, a guy rope dropping switched around the right wingand broke the tower that braced the two rear wings and which also gavecontrol over the tail. We shouted Maloney that the machine was broken, but he probably did not hear us, as he was at the same time saying, "Hurrah for Montgomery's airship, " and as the break was behind him, hemay not have detected it. Now did he know of the breakage or not, and ifhe knew of it did he take a risk so as not to disappoint his friends?At all events, when the machine started on its flight the rear wingscommenced to flap (thus indicating they were loose), the machine turnedon its back, and settled a little faster than a parachute. When wereached Maloney he was unconscious and lived only thirty minutes. Theonly mark of any kind on him was a scratch from a wire on the side ofhis neck. The six attending physicians were puzzled at the cause of hisdeath. This is remarkable for a vertical descent of over 2, 000 feet. ' The flights were brought to an end by the San Francisco earthquake inApril, 1906, which, Montgomery states, 'Wrought such a disaster that Ihad to turn my attention to other subjects and let the aeroplane restfor a time. ' Montgomery resumed experiments in 1911 in California, andin October of that year an accident brought his work to an end. Thereport in the American Aeronautics says that 'a little whirlwind caughtthe machine and dashed it head on to the ground; Professor Montgomerylanded on his head and right hip. He did not believe himself seriouslyhurt, and talked with his year-old bride in the tent. He complained ofpains in his back, and continued to grow worse until he died. ' IX. NOT PROVEN The early history of flying, like that of most sciences, is repletewith tragedies; in addition to these it contains one mystery concerningClement Ader, who was well known among European pioneers in thedevelopment of the telephone, and first turned his attention to theproblems of mechanical flight in 1872. At the outset he favoured theornithopter principle, constructing a machine in the form of a bird witha wing-spread of twenty-six feet; this, according to Ader's conception, was to fly through the efforts of the operator. The result of suchan attempt was past question and naturally the machine never left theground. A pause of nineteen years ensued, and then in 1886 Ader turned his mindto the development of the aeroplane, constructing a machine of bat-likeform with a wingspread of about forty-six feet, a weight of elevenhundred pounds, and a steam-power plant of between twenty and thirtyhorse-power driving a four-bladed tractor screw. On October 9th, 1890, the first trials of this machine were made, and it was alleged to haveflown a distance of one hundred and sixty-four feet. Whatever truththere may be in the allegation, the machine was wrecked throughdeficient equilibrium at the end of the trial. Ader repeated theconstruction, and on October 14th, 1897, tried out his third machineat the military establishment at Satory in the presence of the Frenchmilitary authorities, on a circular track specially prepared for theexperiment. Ader and his friends alleged that a flight of nearly athousand feet was made; again the machine was wrecked at the end of thetrial, and there Ader's practical work may be said to have ended, sinceno more funds were forthcoming for the subsidy of experiments. There is the bald narrative, but it is worthy of some amplification. IfAder actually did what he claimed, then the position which the WrightBrothers hold as first to navigate the air in a power-driven plane isnullified. Although at this time of writing it is not a quarter of acentury since Ader's experiment in the presence of witnesses competentto judge on his accomplishment, there is no proof either way, andwhether he was or was not the first man to fly remains a mystery in thestory of the conquest of the air. The full story of Ader's work reveals a persistence and determination tosolve the problem that faced him which was equal to that of Lilienthal. He began by penetrating into the interior of Algeria after havingdisguised himself as an Arab, and there he spent some months in studyingflight as practiced by the vultures of the district. Returning to Francein 1886 he began to construct the 'Eole, ' modelling it, not on thevulture, but in the shape of a bat. Like the Lilienthal and Pilchergliders this machine was fitted with wings which could be folded; thefirst flight made, as already noted, on October 9th, 1890, took placein the grounds of the chateau d'Amainvilliers, near Bretz; twofellow-enthusiasts named Espinosa and Vallier stated that a flightwas actually made; no statement in the history of aeronautics has beensubject of so much question, and the claim remains unproved. It was in September of 1891 that Ader, by permission of the Minister ofWar, moved the 'Eole' to the military establishment at Satory for thepurpose of further trial. By this time, whether he had flown or not, his nineteen years of work in connection with the problems attendant onmechanical flight had attracted so much attention that henceforthhis work was subject to the approval of the military authorities, foralready it was recognised that an efficient flying machine would conferan inestimable advantage on the power that possessed it in the eventof war. At Satory the 'Eole' was alleged to have made a flight of 109yards, or, according to another account, 164 feet, as stated above, inthe trial in which the machine wrecked itself through colliding withsome carts which had been placed near the track--the root cause of thisaccident, however, was given as deficient equilibrium. Whatever the sceptics may say, there is reason for belief in theaccomplishment of actual flight by Ader with his first machine in thefact that, after the inevitable official delay of some months, theFrench War Ministry granted funds for further experiment. Ader namedhis second machine, which he began to build in May, 1892, the 'Avion, 'and--an honour which he well deserve--that name remains in Frenchaeronautics as descriptive of the power-driven aeroplane up to this day. This second machine, however, was not a success, and it was not until1897 that the second 'Avion, ' which was the third power-driven aeroplaneof Ader's construction, was ready for trial. This was fitted withtwo steam motors of twenty horse-power each, driving two four-bladedpropellers; the wings warped automatically: that is to say, if itwere necessary to raise the trailing edge of one wing on the turn, the trailing edge of the opposite wing was also lowered by the samemovement; an under-carriage was also fitted, the machine running onthree small wheels, and levers controlled by the feet of the aviatoractuated the movement of the tail planes. On October the 12th, 1897, the first trials of this 'Avion' were madein the presence of General Mensier, who admitted that the machine madeseveral hops above the ground, but did not consider the performance asone of actual flight. The result was so encouraging, in spite of thepartial failure, that, two days later, General Mensier, accompanied byGeneral Grillon, a certain Lieutenant Binet, and two civilians namedrespectively Sarrau and Leaute, attended for the purpose of giving themachine an official trial, over which the great controversy regardingAder's success or otherwise may be said to have arisen. We will take first Ader's own statement as set out in a very competentaccount of his work published in Paris in 1910. Here are Ader's ownwords: 'After some turns of the propellers, and after travelling a fewmetres, we started off at a lively pace; the pressure-gauge registeredabout seven atmospheres; almost immediately the vibrations of the rearwheel ceased; a little later we only experienced those of the frontwheels at intervals. 'Unhappily, the wind became suddenly strong, andwe had some difficulty in keeping the "Avion" on the white line. Weincreased the pressure to between eight and nine atmospheres, andimmediately the speed increased considerably, and the vibrations ofthe wheels were no longer sensible; we were at that moment at the pointmarked G in the sketch; the "Avion" then found itself freely supportedby its wings; under the impulse of the wind it continually tended to gooutside the (prepared) area to the right, in spite of the action ofthe rudder. On reaching the point V it found itself in a very criticalposition; the wind blew strongly and across the direction of the whiteline which it ought to follow; the machine then, although still goingforward, drifted quickly out of the area; we immediately put over therudder to the left as far as it would go; at the same time increasingthe pressure still more, in order to try to regain the course. The"Avion" obeyed, recovered a little, and remained for some seconds headedtowards its intended course, but it could not struggle against the wind;instead of going back, on the contrary it drifted farther and fartheraway. And ill-luck had it that the drift took the direction towardspart of the School of Musketry, which was guarded by posts andbarriers. Frightened at the prospect of breaking ourselves against theseobstacles, surprised at seeing the earth getting farther away from underthe "Avion, " and very much impressed by seeing it rushing sideways ata sickening speed, instinctively we stopped everything. What passedthrough our thoughts at this moment which threatened a tragic turn wouldbe difficult to set down. All at once came a great shock, splintering, aheavy concussion: we had landed. ' Thus speaks the inventor; the cold official mind gives out a differentaccount, crediting the 'Avion' with merely a few hops, and to-day, amongthose who consider the problem at all, there is a little group whichpersists in asserting that to Ader belongs the credit of the firstpower-driven flight, while a larger group is equally persistent instating that, save for a few ineffectual hops, all three wheels of themachine never left the ground. It is past question that the 'Avion' wascapable of power-driven flight; whether it achieved it or no remains anunsettled problem. Ader's work is negative proof of the value of such experiments asLilienthal, Pilcher, Chanute, and Montgomery conducted; these four setto work to master the eccentricities of the air before attempting touse it as a supporting medium for continuous flight under power; Aderattacked the problem from the other end; like many other experimentershe regarded the air as a stable fluid capable of giving such support tohis machine as still water might give to a fish, and he reckoned that hehad only to produce the machine in order to achieve flight. The wrecked'Avion' and the refusal of the French War Ministry to grant any morefunds for further experiment are sufficient evidence of the need forworking along the lines taken by the pioneers of gliding rather than onthose which Ader himself adopted. Let it not be thought that in this comment there is any desire toderogate from the position which Ader should occupy in any study ofthe pioneers of aeronautical enterprise. If he failed, he failedmagnificently, and if he succeeded, then the student of aeronautics doeshim an injustice and confers on the Brothers Wright an honour which, in spite of the value of their work, they do not deserve. There wasone earlier than Ader, Alphonse Penaud, who, in the face of a lesserdisappointment than that which Ader must have felt in gazing on thewreckage of his machine, committed suicide; Ader himself, renderedunable to do more, remained content with his achievement, and with theknowledge that he had played a good part in the long search which musteventually end in triumph. Whatever the world might say, he himself wascertain that he had achieved flight. This, for him, was perforce enough. Before turning to consideration of the work accomplished by the BrothersWright, and their proved conquest of the air, it is necessary first tosketch as briefly as may be the experimental work of Sir (then Mr) HiramMaxim, who, in his book, Artificial and Natural Flight, has givena fairly complete account of his various experiments. He began byexperimenting with models, with screw-propelled planes so attached to ahorizontal movable arm that when the screw was set in motion the planedescribed a circle round a central point, and, eventually, he built agiant aeroplane having a total supporting area of 1, 500 square feet, and a wing-span of fifty feet. It has been thought advisable to givea fairly full description of the power plant used to the propulsionof this machine in the section devoted to engine development. Theaeroplane, as Maxim describes it, had five long and narrow planesprojecting from each side, and a main or central plane of pterygoidaspect. A fore and aft rudder was provided, and had all the auxiliaryplanes been put in position for experimental work a total liftingsurface of 6, 000 square feet could have been obtained. Maxim, however, did not use more than 4, 000 square feet of lifting surface even in hislater experiments; with this he judged the machine capable of liftingslightly under 8, 000 lbs. Weight, made up of 600 lbs. Water in theboiler and tank, a crew of three men, a supply of naphtha fuel, and theweight of the machine itself. Maxim's intention was, before attempting free flight, to get as muchdata as possible regarding the conditions under which flight must beobtained, by what is known in these days as 'taxi-ing'--that is, runningthe propellers at sufficient speed to drive the machine along the groundwithout actually mounting into the air. He knew that he had an immenselifting surface and a tremendous amount of power in his engine even whenthe total weight of the experimental plant was taken into consideration, and thus he set about to devise some means of keeping the machine on thenine foot gauge rail track which had been constructed for the trials. Atthe outset he had a set of very heavy cast-iron wheels made on which tomount the machine, the total weight of wheels, axles, and connectionsbeing about one and a half tons. These were so constructed that thelight flanged wheels which supported the machine on the steel railscould be lifted six inches above the track, still leaving the heavywheels on the rails for guidance of the machine. 'This arrangement, 'Maxim states, 'was tried on several occasions, the machine being runfast enough to lift the forward end off the track. However, I foundconsiderable difficulty in starting and stopping quickly on account ofthe great weight, and the amount of energy necessary to set such heavywheels spinning at a high velocity. The last experiment with thesewheels was made when a head wind was blowing at the rate of about tenmiles an hour. It was rather unsteady, and when the machine was runningat its greatest velocity, a sudden gust lifted not only the frontend, but also the heavy front wheels completely off the track, and themachine falling on soft ground was soon blown over by the wind. ' Consequently, a safety track was provided, consisting of squared pinelogs, three inches by nine inches, placed about two feet above the steelway and having a thirty-foot gauge. Four extra wheels were fitted to themachine on outriggers and so adjusted that, if the machine shouldlift one inch clear of the steel rails, the wheels at the ends of theoutriggers would engage the under side of the pine trackway. The first fully loaded run was made in a dead calm with 150 lbs. Steampressure to the square inch, and there was no sign of the wheels leavingthe steel track. On a second run, with 230 lbs. Steam pressure themachine seemed to alternate between adherence to the lower and uppertracks, as many as three of the outrigger wheels engaging at the sametime, and the weight on the steel rails being reduced practically tonothing. In preparation for a third run, in which it was intended to usefull power, a dynamometer was attached to the machine and the engineswere started at 200 lbs. Pressure, which was gradually increased to 310lbs per square inch. The incline of the track, added to the reading ofthe dynamometer, showed a total screw thrust of 2, 164 lbs. After thedynamometer test had been completed, and everything had been made readyfor trial in motion, careful observers were stationed on each side ofthe track, and the order was given to release the machine. What followsis best told in Maxim's own words:-- 'The enormous screw-thrust started the engine so quickly that it nearlythrew the engineers off their feet, and the machine bounded over thetrack at a great rate. Upon noticing a slight diminution in thesteam pressure, I turned on more gas, when almost instantly the steamcommenced to blow a steady blast from the small safety valve, showingthat the pressure was at least 320 lbs. In the pipes supplying theengines with steam. Before starting on this run, the wheels that wereto engage the upper track were painted, and it was the duty of one ofmy assistants to observe these wheels during the run, while anotherassistant watched the pressure gauges and dynagraphs. The first part ofthe track was up a slight incline, but the machine was lifted clearof the lower rails and all of the top wheels were fully engaged on theupper track when about 600 feet had been covered. The speed rapidlyincreased, and when 900 feet had been covered, one of the rear axletrees, which were of two-inch steel tubing, doubled up and set the rearend of the machine completely free. The pencils ran completely acrossthe cylinders of the dynagraphs and caught on the underneath end. Therear end of the machine being set free, raised considerably above thetrack and swayed. At about 1, 000 feet, the left forward wheel also gotclear of the upper track, and shortly afterwards the right forward wheeltore up about 100 feet of the upper track. Steam was at once shut offand the machine sank directly to the earth, embedding the wheels in thesoft turf without leaving any other marks, showing most conclusivelythat the machine was completely suspended in the air before it settledto the earth. In this accident, one of the pine timbers forming theupper track went completely through the lower framework of the machineand broke a number of the tubes, but no damage was done to the machineryexcept a slight injury to one of the screws. ' It is a pity that the multifarious directions in which Maxim turned hisenergies did not include further development of the aeroplane, for itseems fairly certain that he was as near solution of the problem as Aderhimself, and, but for the holding-down outer track, which was really thecause of his accident, his machine would certainly have achieved freeflight, though whether it would have risen, flown and alighted, withoutaccident, is matter for conjecture. The difference between experiments with models and with full-sizedmachines is emphasised by Maxim's statement to the effect that witha small apparatus for ascertaining the power required for artificialflight, an angle of incidence of one in fourteen was most advantageous, while with a large machine he found it best to increase his angle to onein eight in order to get the maximum lifting effect on a short run at amoderate speed. He computed the total lifting effect in the experimentswhich led to the accident as not less than 10, 000 lbs. , in which isproof that only his rail system prevented free flight. X. SAMUEL PIERPOINT LANGLEY Langley was an old man when he began the study of aeronautics, or, ashe himself might have expressed it, the study of aerodromics, since hepersisted in calling the series of machines he built 'Aerodromes, ' aword now used only to denote areas devoted to use as landing spaces forflying machines; the Wright Brothers, on the other hand, had the greatgift of youth to aid them in their work. Even so it was a great racebetween Langley, aided by Charles Manly, and Wilbur and Orville Wright, and only the persistent ill-luck which dogged Langley from the start tothe finish of his experiments gave victory to his rivals. It has beenproved conclusively in these later years of accomplished flight that themachine which Langley launched on the Potomac River in October of 1903was fully capable of sustained flight, and only the accidents incurredin launching prevented its pilot from being the first man to navigatethe air successfully in a power-driven machine. The best account of Langley's work is that diffused throughout a weightytome issued by the Smithsonian Institution, entitled the Langley Memoiron Mechanical Flight, of which about one-third was written by Langleyhimself, the remainder being compiled by Charles M. Manly, the engineerresponsible for the construction of the first radial aero-engine, andchief assistant to Langley in his experiments. To give a twentiethof the contents of this volume in the present short account of thedevelopment of mechanical flight would far exceed the amount of spacethat can be devoted even to so eminent a man in aeronautics as S. P. Langley, who, apart from his achievement in the construction of apower-driven aeroplane really capable of flight, was a scientist of nomean order, and who brought to the study of aeronautics the skill of thetrained investigator allied to the inventive resource of the genius. That genius exemplified the antique saw regarding the infinite capacityfor taking pains, for the Langley Memoir shows that as early as 1891Langley had completed a set of experiments, lasting through years, which proved it possible to construct machines giving such a velocityto inclined surfaces that bodies indefinitely heavier than air couldbe sustained upon it and propelled through it at high speed. For fullaccount (very full) of these experiments, and of a later series leadingup to the construction of a series of 'model aerodromes' capable offlight under power, it is necessary to turn to the bulky memoir ofSmithsonian origin. The account of these experiments as given by Langley himself revealsthe humility of the true investigator. Concerning them, Langley remarksthat, 'Everything here has been done with a view to putting a trialaerodrome successfully in flight within a few years, and thus giving anearly demonstration of the only kind which is conclusive in the eyes ofthe scientific man, as well as of the general public--a demonstrationthat mechanical flight is possible--by actually flying. All that hasbeen done has been with an eye principally to this immediate result, and all the experiments given in this book are to be considered only asapproximations to exact truth. All were made with a view, not to someremote future, but to an arrival within the compass of a few years atsome result in actual flight that could not be gainsaid or mistaken. ' With a series of over thirty rubber-driven models Langley demonstratedthe practicability of opposing curved surfaces to the resistance of theair in such a way as to achieve flight, in the early nineties of lastcentury; he then set about finding the motive power which should permitof the construction of larger machines, up to man-carrying size. Theinternal combustion engine was then an unknown quantity, and he had toturn to steam, finally, as the propulsive energy for his power plant. The chief problem which faced him was that of the relative weight andpower of his engine; he harked back to the Stringfellow engine of 1868, which in 1889 came into the possession of the Smithsonian Institutionas a historical curiosity. Rightly or wrongly Langley concluded onexamination that this engine never had developed and never coulddevelop more than a tenth of the power attributed to it; consequentlyhe abandoned the idea of copying the Stringfellow design and set aboutmaking his own engine. How he overcame the various difficulties that faced him and constructeda steam-engine capable of the task allotted to it forms a story initself, too long for recital here. His first power-driven aerodromeof model size was begun in November of 1891, the scale of constructionbeing decided with the idea that it should be large enough to carry anautomatic steering apparatus which would render the machine capable ofmaintaining a long and steady flight. The actual weight of the firstmodel far exceeded the theoretical estimate, and Langley found that aconstant increase of weight under the exigencies of construction was afeature which could never be altogether eliminated. The machine was madeprincipally of steel, the sustaining surfaces being composed of silkstretched from a steel tube with wooden attachments. The first engineswere the oscillating type, but were found deficient in power. This ledto the construction of single-acting inverted oscillating engines withhigh and low pressure cylinders, and with admission and exhaust portsto avoid the complication and weight of eccentric and valves. Boiler andfurnace had to be specially designed; an analysis of sustaining surfacesand the settlement of equilibrium while in flight had to be overcome, and then it was possible to set about the construction of the series ofmodel aerodromes and make test of their 'lift. ' By the time Langley had advanced sufficiently far to consider itpossible to conduct experiments in the open air, even with these models, he had got to his fifth aerodrome, and to the year 1894. Certain testsresulted in failure, which in turn resulted in further modifications ofdesign, mainly of the engines. By February of 1895 Langley reportedthat under favourable conditions a lift of nearly sixty per cent ofthe flying weight was secured, but although this was much more thanwas required for flight, it was decided to postpone trials until twomachines were ready for the test. May, 1896, came before actual trialswere made, when one machine proved successful and another, a laterdesign, failed. The difficulty with these models was that of securinga correct angle for launching; Langley records how, on launching onemachine, it rose so rapidly that it attained an angle of sixty degreesand then did a tail slide into the water with its engines working atfull speed, after advancing nearly forty feet and remaining in theair for about three seconds. Here, Langley found that he had to obtaingreater rigidity in his wings, owing to the distortion of the form ofwing under pressure, and how he overcame this difficulty constitutes yetanother story too long for the telling here. Field trials were first attempted in 1893, and Langley blamed hislaunching apparatus for their total failure. There was a brief, but atthe same time practical, success in model flight in 1894, extendingto between six and seven seconds, but this only proved the need forstrengthening of the wing. In 1895 there was practically no advancetoward the solution of the problem, but the flights of May 6th andNovember 28th, 1896, were notably successful. A diagram given inLangley's memoir shows the track covered by the aerodrome on these twoflights; in the first of them the machine made three complete circles, covering a distance of 3, 200 feet; in the second, that of November 28th, the distance covered was 4, 200 feet, or about three-quarters of a mile, at a speed of about thirty miles an hour. These achievements meant a good deal; they proved mechanically propelledflight possible. The difference between them and such experiments aswere conducted by Clement Ader, Maxim, and others, lay principally inthe fact that these latter either did or did not succeed in rising intothe air once, and then, either willingly or by compulsion, gave upthe quest, while Langley repeated his experiments and thus attained toactual proof of the possibilities of flight. Like these others, however, he decided in 1896 that he would not undertake the construction of alarge man-carrying machine. In addition to a multitude of actual duties, which left him practically no time available for original research, hehad as an adverse factor fully ten years of disheartening difficultiesin connection with his model machines. It was President McKinley who, byrequesting Langley to undertake the construction and test of a machinewhich might finally lead to the development of a flying machinecapable of being used in warfare, egged him on to his final experiment. Langley's acceptance of the offer to construct such a machine iscontained in a letter addressed from the Smithsonian Institution onDecember 12th, 1898, to the Board of Ordnance and Fortification of theUnited States War Department; this letter is of such interest as torender it worthy of reproduction:-- 'Gentlemen, --In response to your invitation I repeat what I had thehonour to say to the Board--that I am willing, with the consent of theRegents of this Institution, to undertake for the Government the furtherinvestigation of the subject of the construction of a flying machineon a scale capable of carrying a man, the investigation to include theconstruction, development and test of such a machine under conditionsleft as far as practicable in my discretion, it being understood that myservices are given to the Government in such time as may not be occupiedby the business of the Institution, and without charge. 'I have reason to believe that the cost of the construction will comewithin the sum of $50, 000. 00, and that not more than one-half of thatwill be called for in the coming year. 'I entirely agree with what I understand to be the wish of the Boardthat privacy be observed with regard to the work, and only when itreaches a successful completion shall I wish to make public the fact ofits success. 'I attach to this a memorandum of my understanding of some points ofdetail in order to be sure that it is also the understanding of theBoard, and I am, gentlemen, with much respect, your obedient servant, S. P. Langley. ' One of the chief problems in connection with the construction of afull-sized apparatus was that of the construction of an engine, for itwas realised from the first that a steam power plant for a full-sizedmachine could only be constructed in such a way as to make it a constantmenace to the machine which it was to propel. By this time (1898) theinternal combustion engine had so far advanced as to convince Langleythat it formed the best power plant available. A contract was made forthe delivery of a twelve horse-power engine to weigh not more than ahundred pounds, but this contract was never completed, and it fell toCharles M. Manly to design the five-cylinder radial engine, of which abrief account is included in the section of this work devoted to aeroengines, as the power plant for the Langley machine. The history of the years 1899 to 1903 in the Langley series ofexperiments contains a multitude of detail far beyond the scope ofthis present study, and of interest mainly to the designer. There wereframes, engines, and propellers, to be considered, worked out, andconstructed. We are concerned here mainly with the completed machine andits trials. Of these latter it must be remarked that the only two actualfield trials which took place resulted in accidents due to the failureof the launching apparatus, and not due to any inherent defect in themachine. It was intended that these two trials should be the first ofa series, but the unfortunate accidents, and the fact that no furtherfunds were forthcoming for continuance of experiments, preventedLangley's success, which, had he been free to go through as he intendedwith his work, would have been certain. The best brief description of the Langley aerodrome in its final form, and of the two attempted trials, is contained in the official report ofMajor M. M. Macomb of the United States Artillery Corps, which report ishere given in full:-- REPORT Experiments with working models which were concluded August 8 lasthaving proved the principles and calculations on which the design of theLangley aerodrome was based to be correct, the next step was to applythese principles to the construction of a machine of sufficient sizeand power to permit the carrying of a man, who could control the motivepower and guide its flight, thus pointing the way to attaining the finalgoal of producing a machine capable of such extensive and precise aerialflight, under normal atmospheric conditions, as to prove of military orcommercial utility. Mr C. M. Manly, working under Professor Langley, had, by the summerof 1903, succeeded in completing an engine-driven machine which underfavourable atmospheric conditions was expected to carry a man for anytime up to half an hour, and to be capable of having its flight directedand controlled by him. The supporting surface of the wings was ample, and experiment showed theengine capable of supplying more than the necessary motive power. Owing to the necessity of lightness, the weight of the various elementshad to be kept at a minimum, and the factor of safety in constructionwas therefore exceedingly small, so that the machine as a whole wasdelicate and frail and incapable of sustaining any unusual strain. Thisdefect was to be corrected in later models by utilising data gathered infuture experiments under varied conditions. One of the most remarkable results attained was the production of agasoline engine furnishing over fifty continuous horse-power for aweight of 120 lbs. The aerodrome, as completed and prepared for test, is briefly describedby Professor Langley as 'built of steel, weighing complete about730 lbs. , supported by 1, 040 feet of sustaining surface, having twopropellers driven by a gas engine developing continuously over fiftybrake horse-power. ' The appearance of the machine prepared for flight was exceedingly lightand graceful, giving an impression to all observers of being capable ofsuccessful flight. On October 7 last everything was in readiness, and I witnessed theattempted trial on that day at Widewater, Va. On the Potomac. The engineworked well and the machine was launched at about 12. 15 p. M. The trialwas unsuccessful because the front guy-post caught in its support on thelaunching car and was not released in time to give free flight, as wasintended, but, on the contrary, caused the front of the machine to bedragged downward, bending the guy-post and making the machine plungeinto the water about fifty yards in front of the house-boat. The machinewas subsequently recovered and brought back to the house-boat. Theengine was uninjured and the frame only slightly damaged, but the fourwings and rudder were practically destroyed by the first plunge andsubsequent towing back to the house-boat. This accident necessitated the removal of the house-boat to Washingtonfor the more convenient repair of damages. On December 8 last, between 4 and 5 p. M. , another attempt at a trial wasmade, this time at the junction of the Anacostia with the Potomac, justbelow Washington Barracks. On this occasion General Randolph and myself represented the Board ofOrdnance and Fortification. The launching car was released at 4. 45 p. M. Being pointed up the Anacostia towards the Navy Yard. My position wason the tug Bartholdi, about 150 feet from and at right angles tothe direction of proposed flight. The car was set in motion and thepropellers revolved rapidly, the engine working perfectly, but there wassomething wrong with the launching. The rear guy-post seemed to drag, bringing the rudder down on the launching ways, and a crashing, rendingsound, followed by the collapse of the rear wings, showed that themachine had been wrecked in the launching, just how, it was impossiblefor me to see. The fact remains that the rear wings and rudder werewrecked before the machine was free of the ways. Their collapse deprivedthe machine of its support in the rear, and it consequently reared upin front under the action of the motor, assumed a vertical position, and then toppled over to the rear, falling into the water a few feet infront of the boat. Mr Manly was pulled out of the wreck uninjured and the wreckedmachine--was subsequently placed upon the house-boat, and the wholebrought back to Washington. From what has been said it will be seen that these unfortunate accidentshave prevented any test of the apparatus in free flight, and the claimthat an engine-driven, man-carrying aerodrome has been constructed lacksthe proof which actual flight alone can give. Having reached the present stage of advancement in its development, itwould seem highly desirable, before laying down the investigation, toobtain conclusive proof of the possibility of free flight, not onlybecause there are excellent reasons to hope for success, but becauseit marks the end of a definite step toward the attainment of the finalgoal. Just what further procedure is necessary to secure successful flightwith the large aerodrome has not yet been decided upon. ProfessorLangley is understood to have this subject under advisement, andwill doubtless inform the Board of his final conclusions as soon aspracticable. In the meantime, to avoid any possible misunderstanding, it should bestated that even after a successful test of the present great aerodrome, designed to carry a man, we are still far from the ultimate goal, and itwould seem as if years of constant work and study by experts, togetherwith the expenditure of thousands of dollars, would still be necessarybefore we can hope to produce an apparatus of practical utility on theselines. --Washington, January 6, 1904. A subsequent report of the Board of ordnance and Fortification to theSecretary of War embodied the principal points in Major Macomb's report, but as early as March 3rd, 1904, the Board came to a similar conclusionto that of the French Ministry of War in respect of Clement Ader's work, stating that it was not 'prepared to make an additional allotmentat this time for continuing the work. ' This decision was in no smallmeasure due to hostile newspaper criticisms. Langley, in a letter tothe press explaining his attitude, stated that he did not wish to makepublic the results of his work till these were certain, in consequenceof which he refused admittance to newspaper representatives, and thisattitude produced a hostility which had effect on the United StatesCongress. An offer was made to commercialise the invention, but Langleysteadfastly refused it. Concerning this, Manly remarks that Langleyhad 'given his time and his best labours to the world without hope ofremuneration, and he could not bring himself, at his stage of life, toconsent to capitalise his scientific work. ' The final trial of the Langley aerodrome was made on December 8th, 1903;nine days later, on December 17th, the Wright Brothers made their firstflight in a power-propelled machine, and the conquest of the air wasthus achieved. But for the two accidents that spoilt his trials, thehonour which fell to the Wright Brothers would, beyond doubt, have beensecured by Samuel Pierpoint Langley. XI. THE WRIGHT BROTHERS Such information as is given here concerning the Wright Brothers isderived from the two best sources available, namely, the writings ofWilbur Wright himself, and a lecture given by Dr Griffith Brewer tomembers of the Royal Aeronautical Society. There is no doubt that sofar as actual work in connection with aviation accomplished by the twobrothers is concerned, Wilbur Wright's own statements are the clearestand best available. Apparently Wilbur was, from the beginning, thehistorian of the pair, though he himself would have been the last toattempt to detract in any way from the fame that his brother's work alsodeserves. Throughout all their experiments the two were inseparable, and their work is one indivisible whole; in fact, in every departmentof that work, it is impossible to say where Orville leaves off and whereWilbur begins. It is a great story, this of the Wright Brothers, and one worth all thedetail that can be spared it. It begins on the 16th April, 1867, whenWilbur Wright was born within eight miles of Newcastle, Indiana. BeforeOrville's birth on the 19th August, 1871, the Wright family had movedto Dayton, Ohio, and settled on what is known as the 'West Side' of thetown. Here the brothers grew up, and, when Orville was still a boy inhis teens, he started a printing business, which, as Griffith Brewerremarks, was only limited by the smallness of his machine and smallquantity of type at his disposal. This machine was in such a state thatpieces of string and wood were incorporated in it by way of repair, buton it Orville managed to print a boys' paper which gained considerablepopularity in Dayton 'West Side. ' Later, at the age of seventeen, he obtained a more efficient outfit, with which he launched a weeklynewspaper, four pages in size, entitled The West Side News. After threemonths' running the paper was increased in size and Wilbur came intothe enterprise as editor, Orville remaining publisher. In 1894 the twobrothers began the publication of a weekly magazine, Snap-Shots, towhich Wilbur contributed a series of articles on local affairs that gaveevidence of the incisive and often sarcastic manner in which he was ableto express himself throughout his life. Dr Griffith Brewer describes himas a fearless critic, who wrote on matters of local interest in a kindlybut vigorous manner, which did much to maintain the healthy publicmunicipal life of Dayton. Editorial and publishing enterprise was succeeded by the formation, justacross the road from the printing works, of the Wright Cycle Company, where the two brothers launched out as cycle manufacturers with the'Van Cleve' bicycle, a machine of great local repute for excellence ofconstruction, and one which won for itself a reputation that lasted longafter it had ceased to be manufactured. The name of the machine was thatof an ancestor of the brothers, Catherine Van Cleve, who was one of thefirst settlers at Dayton, landing there from the River Miami on April1st, 1796, when the country was virgin forest. It was not until 1896 that the mechanical genius which characterisedthe two brothers was turned to the consideration of aeronautics. In thatyear they took up the problem thoroughly, studying all the aeronauticalinformation then in print. Lilienthal's writings formed one basis fortheir studies, and the work of Langley assisted in establishing inthem a confidence in the possibility of a solution to the problems ofmechanical flight. In 1909, at the banquet given by the Royal Aero Clubto the Wright Brothers on their return to America, after the series ofdemonstration flights carried out by Wilbur Wright on the Continent, Wilbur paid tribute to the great pioneer work of Stringfellow, whosestudies and achievements influenced his own and Orville's early work. Hepointed out how Stringfellow devised an aeroplane having two propellersand vertical and horizontal steering, and gave due place to this earlypioneer of mechanical flight. Neither of the brothers was content with mere study of the work ofothers. They collected all the theory available in the books publishedup to that time, and then built man-carrying gliders with which to testthe data of Lilienthal and such other authorities as they had consulted. For two years they conducted outdoor experiments in order to test thetruth or otherwise of what were enunciated as the principles of flight;after this they turned to laboratory experiments, constructing a windtunnel in which they made thousands of tests with models of variousforms of curved planes. From their experiments they tabulated thousandsof readings, which Griffith Brewer remarks as giving results equallyefficient with those of the elaborate tables prepared by learnedinstitutions. Wilbur Wright has set down the beginnings of the practical experimentsmade by the two brothers very clearly. 'The difficulties, ' he says, 'which obstruct the pathway to success in flying machine constructionare of three general classes: (1) Those which relate to the constructionof the sustaining wings; (2) those which relate to the generation andapplication of the power required to drive the machine through the air;(3) those relating to the balancing and steering of the machine afterit is actually in flight. Of these difficulties two are already toa certain extent solved. Men already know how to construct wings, oraeroplanes, which, when driven through the air at sufficient speed, willnot only sustain the weight of the wings themselves, but also that ofthe engine and the engineer as well. Men also know how to build enginesand' screws of sufficient lightness and power to drive these planesat sustaining speed. Inability to balance and steer still confrontsstudents of the flying problem, although nearly ten years have passed(since Lilienthal's success). When this one feature has been worked out, the age of flying machines will have arrived, for all other difficultiesare of minor importance. 'The person who merely watches the flight of a bird gathers theimpression that the bird has nothing to think of but the flapping ofits wings. As a matter of fact, this is a very small part of its mentallabour. Even to mention all the things the bird must constantly keep inmind in order to fly securely through the air would take a considerabletime. If I take a piece of paper and, after placing it parallel withthe ground, quickly let it fall, it will not settle steadily down asa staid, sensible piece of paper ought to do, but it insists oncontravening every recognised rule of decorum, turning over and dartinghither and thither in the most erratic manner, much after the style ofan untrained horse. Yet this is the style of steed that men must learnto manage before flying can become an everyday sport. The bird haslearned this art of equilibrium, and learned it so thoroughly that itsskill is not apparent to our sight. We only learn to appreciate it whenwe can imitate it. 'Now, there are only two ways of learning to ride a fractious horse: oneis to get on him and learn by actual practice how each motion and trickmay be best met; the other is to sit on a fence and watch the beastawhile, and then retire to the house and at leisure figure out the bestway of overcoming his jumps and kicks. The latter system is the safer, but the former, on the whole, turns out the larger proportion of goodriders. It is very much the same in learning to ride a flying machine;if you are looking for perfect safety you will do well to sit on a fenceand watch the birds, but if you really wish to learn you must mounta machine and become acquainted with its tricks by actual trial. Thebalancing of a gliding or flying machine is very simple in theory. Itmerely consists in causing the centre of pressure to coincide with thecentre of gravity. ' These comments are taken from a lecture delivered by Wilbur Wrightbefore the Western Society of Engineers in September of 1901, under thepresidency of Octave Chanute. In that lecture Wilbur detailed the wayin which he and his brother came to interest themselves in aeronauticalproblems and constructed their first glider. He speaks of his ownnotice of the death of Lilienthal in 1896, and of the way in which thisfatality roused him to an active interest in aeronautical problems, which was stimulated by reading Professor Marey's Animal Mechanism, notfor the first time. 'From this I was led to read more modern works, andas my brother soon became equally interested with myself, we soon passedfrom the reading to the thinking, and finally to the working stage. Itseemed to us that the main reason why the problem had remained so longunsolved was that no one had been able to obtain any adequate practice. We figured that Lilienthal in five years of time had spent only aboutfive hours in actual gliding through the air. The wonder was not that hehad done so little, but that he had accomplished so much. It would notbe considered at all safe for a bicycle rider to attempt to ride througha crowded city street after only five hours' practice, spread out inbits of ten seconds each over a period of five years; yet Lilienthalwith this brief practice was remarkably successful in meeting thefluctuations and eddies of wind-gusts. We thought that if some methodcould be found by which it would be possible to practice by the hourinstead of by the second there would be hope of advancing the solutionof a very difficult problem. It seemed feasible to do this by building amachine which would be sustained at a speed of eighteen miles per hour, and then finding a locality where winds of this velocity were common. With these conditions a rope attached to the machine to keep it fromfloating backward would answer very nearly the same purpose as apropeller driven by a motor, and it would be possible to practice by thehour, and without any serious danger, as it would not be necessary torise far from the ground, and the machine would not have any forwardmotion at all. We found, according to the accepted tables of airpressure on curved surfaces, that a machine spreading 200 square feet ofwing surface would be sufficient for our purpose, and that places wouldeasily be found along the Atlantic coast where winds of sixteen totwenty-five miles were not at all uncommon. When the winds were low itwas our plan to glide from the tops of sandhills, and when they weresufficiently strong to use a rope for our motor and fly over one spot. Our next work was to draw up the plans for a suitable machine. Aftermuch study we finally concluded that tails were a source of troublerather than of assistance, and therefore we decided to dispense withthem altogether. It seemed reasonable that if the body of the operatorcould be placed in a horizontal position instead of the upright, as inthe machines of Lilienthal, Pilcher, and Chanute, the wind resistancecould be very materially reduced, since only one square foot instead offive would be exposed. As a full half horse-power would be saved by thischange, we arranged to try at least the horizontal position. Then themethod of control used by Lilienthal, which consisted in shifting thebody, did not seem quite as quick or effective as the case required; so, after long study, we contrived a system consisting of two large surfaceson the Chanute double-deck plan, and a smaller surface placed a shortdistance in front of the main surfaces in such a position that theaction of the wind upon it would counterbalance the effect of the travelof the centre of pressure on the main surfaces. Thus changes in thedirection and velocity of the wind would have little disturbing effect, and the operator would be required to attend only to the steering of themachine, which was to be effected by curving the forward surface up ordown. The lateral equilibrium and the steering to right or left wasto be attained by a peculiar torsion of the main surfaces which wasequivalent to presenting one end of the wings at a greater angle thanthe other. In the main frame a few changes were also made in the detailsof construction and trussing employed by Mr Chanute. The most importantof these were: (1) The moving of the forward main crosspiece of theframe to the extreme front edge; (2) the encasing in the cloth of allcrosspieces and ribs of the surfaces; (3) a rearrangement of the wiresused in trussing the two surfaces together, which rendered it possibleto tighten all the wires by simply shortening two of them. ' The brothers intended originally to get 200 square feet of supportingsurface for their glider, but the impossibility of obtaining suitablematerial compelled them to reduce the area to 165 square feet, which, bythe Lilienthal tables, admitted of support in a wind of about twenty-onemiles an hour at an angle of three degrees. With this glider they wentin the summer of I 1900 to the little settlement of Kitty Hawk, NorthCarolina, situated on the strip of land dividing Albemarle Sound fromthe Atlantic. Here they reckoned on obtaining steady wind, and here, onthe day that they completed the machine, they took it out for trial asa kite with the wind blowing at between twenty-five and thirty milesan hour. They found that in order to support a man on it the gliderrequired an angle nearer twenty degrees than three, and even with thewind at thirty miles an hour they could not get down to the plannedangle of three degrees. 'Later, when the wind was too light to supportthe machine with a man on it, they tested it as a kite, working therudders by cords. Although they obtained satisfactory results in thisway they realised fully that actual gliding experience was necessarybefore the tests could be considered practical. A series of actual measurements of lift and drift of the machine gaveastonishing results. 'It appeared that the total horizontal pull of themachine, while sustaining a weight of 52 lbs. , was only 8. 5 lbs. , whichwas less than had been previously estimated for head resistance of theframing alone. Making allowance for the weight carried, it appeared thatthe head resistance of the framing was but little more than fifty percent of the amount which Mr Chanute had estimated as the head resistanceof the framing of his machine. On the other hand, it appeared sadlydeficient in lifting power as compared with the calculated lift ofcurved surfaces of its size... We decided to arrange our machine for thefollowing year so that the depth of curvature of its surfaces could bevaried at will, and its covering air-proofed. ' After these experiments the brothers decided to turn to practicalgliding, for which they moved four miles to the south, to the Kill Devilsandhills, the principal of which is slightly over a hundred feetin height, with an inclination of nearly ten degrees on its mainnorth-western slope. On the day after their arrival they made about adozen glides, in which, although the landings were made at a speed ofmore than twenty miles an hour, no injury was sustained either by themachine or by the operator. 'The slope of the hill was 9. 5 degrees, or a drop of one foot in six. Wefound that after attaining a speed of about twenty-five to thirty mileswith reference to the wind, or ten to fifteen miles over the ground, themachine not only glided parallel to the slope of the hill, but greatlyincreased its speed, thus indicating its ability to glide on a somewhatless angle than 9. 5 degrees, when we should feel it safe to rise higherfrom the surface. The control of the machine proved even better than wehad dared to expect, responding quickly to the slightest motion of therudder. With these glides our experiments for the year 1900 closed. Although the hours and hours of practice we had hoped to obtain finallydwindled down to about two minutes, we were very much pleased with thegeneral results of the trip, for, setting out as we did with almostrevolutionary theories on many points and an entirely untried form ofmachine, we considered it quite a point to be able to return withouthaving our pet theories completely knocked on the head by the hard logicof experience, and our own brains dashed out in the bargain. Everythingseemed to us to confirm the correctness of our original opinions:(1) That practice is the key to the secret of flying; (2) that itis practicable to assume the horizontal position; (3) that a smallersurface set at a negative angle in front of the main bearing surfaces, or wings, will largely counteract the effect of the fore and aft travelof the centre of pressure; (4) that steering up and down can be attainedwith a rudder without moving the position of the operator's body; (5)that twisting the wings so as to present their ends to the wind atdifferent angles is a more prompt and efficient way of maintaininglateral equilibrium than shifting the body of the operator. ' For the gliding experiments of 1901 it was decided to retain the form ofthe 1900 glider, but to increase the area to 308 square feet, which, thebrothers calculated, would support itself and its operator in a windof seventeen miles an hour with an angle of incidence of three degrees. Camp was formed at Kitty Hawk in the middle of July, and on July 27ththe machine was completed and tried for the first time in a wind ofabout fourteen miles an hour. The first attempt resulted in landingafter a glide of only a few yards, indicating that the centre of gravitywas too far in front of the centre of pressure. By shifting his positionfarther and farther back the operator finally achieved an undulatingflight of a little over 300 feet, but to obtain this success he had touse full power of the rudder to prevent both stalling and nose-diving. With the 1900 machine one-fourth of the rudder action had been necessaryfor far better control. Practically all glides gave the same result, and in one the machine rosehigher and higher until it lost all headway. 'This was the position fromwhich Lilienthal had always found difficulty in extricating himself, as his machine then, in spite of his greatest exertions, manifested atendency to dive downward almost vertically and strike the ground headon with frightful velocity. In this case a warning cry from the groundcaused the operator to turn the rudder to its full extent and also tomove his body slightly forward. The machine then settled slowly to theground, maintaining its horizontal position almost perfectly, and landedwithout any injury at all. This was very encouraging, as it showed thatone of the very greatest dangers in machines with horizontal tails hadbeen overcome by the use of the front rudder. Several glides later thesame experience was repeated with the same result. In the latter casethe machine had even commenced to move backward, but was neverthelessbrought safely to the ground in a horizontal position. On the whole thisday's experiments were encouraging, for while the action of the rudderdid not seem at all like that of our 1900 machine, yet we had escapedwithout difficulty from positions which had proved very dangerousto preceding experimenters, and after less than one minute's actualpractice had made a glide of more than 300 feet, at an angle ofdescent of ten degrees, and with a machine nearly twice as large as hadpreviously been considered safe. The trouble with its control, whichhas been mentioned, we believed could be corrected when we should havelocated its cause. ' It was finally ascertained that the defect could be remedied bytrussing down the ribs of the whole machine so as to reduce the depth ofcurvature. When this had been done gliding was resumed, and after a fewtrials glides of 366 and 389 feet were made with prompt response on thepart of the machine, even to small movements of the rudder. The rest ofthe story of the gliding experiments of 1901 cannot be better told thanin Wilbur Wright's own words, as uttered by him in the lecture fromwhich the foregoing excerpts have been made. 'The machine, with its new curvature, never failed to respond promptlyto even small movements of the rudder. The operator could cause it toalmost skim the ground, following the undulations of its surface, or hecould cause it to sail out almost on a level with the starting point, and, passing high above the foot of the hill, gradually settle down tothe ground. The wind on this day was blowing eleven to fourteen milesper hour. The next day, the conditions being favourable, the machinewas again taken out for trial. This time the velocity of the wind waseighteen to twenty-two miles per hour. At first we felt some doubt as tothe safety of attempting free flight in so strong a wind, with a machineof over 300 square feet and a practice of less than five minutes spentin actual flight. But after several preliminary experiments we decidedto try a glide. The control of the machine seemed so good that we thenfelt no apprehension in sailing boldly forth. And thereafter we madeglide after glide, sometimes following the ground closely and sometimessailing high in the air. Mr Chanute had his camera with him and tookpictures of some of these glides, several of which are among thoseshown. 'We made glides on subsequent days, whenever the conditions werefavourable. The highest wind thus experimented in was a little overtwelve metres per second--nearly twenty-seven miles per hour. It had been our intention when building the machine to do the largerpart of the experimenting in the following manner:--When the wind blewseventeen miles an hour, or more, we would attach a rope to the machineand let it rise as a kite with the operator upon it. When it shouldreach a proper height the operator would cast off the rope and glidedown to the ground just as from the top of a hill. In this way we wouldbe saved the trouble of carrying the machine uphill after each glide, and could make at least ten glides in the time required for one in theother way. But when we came to try it, we found that a wind of seventeenmiles, as measured by Richards' anemometer, instead of sustaining themachine with its operator, a total weight of 240 lbs. , at an angle ofincidence of three degrees, in reality would not sustain the machinealone--100 lbs. --at this angle. Its lifting capacity seemed scarcely onethird of the calculated amount. In order to make sure that this was notdue to the porosity of the cloth, we constructed two small experimentalsurfaces of equal size, one of which was air-proofed and the other leftin its natural state; but we could detect no difference in their liftingpowers. For a time we were led to suspect that the lift of curvedsurfaces very little exceeded that of planes of the same size, butfurther investigation and experiment led to the opinion that (1) theanemometer used by us over-recorded the true velocity of the wind bynearly 15 per cent; (2) that the well-known Smeaton co-efficient of. 005V squared for the wind pressure at 90 degrees is probably too great byat least 20 per cent; (3) that Lilienthal's estimate that the pressureon a curved surface having an angle of incidence of 3 degrees equals. 545of the pressure at go degrees is too large, being nearly 50 percent greater than very recent experiments of our own with a pressuretesting-machine indicate; (4) that the superposition of the surfacessomewhat reduced the lift per square foot, as compared with a singlesurface of equal area. 'In gliding experiments, however, the amount of lift is of less relativeimportance than the ratio of lift to drift, as this alone decidesthe angle of gliding descent. In a plane the pressure is alwaysperpendicular to the surface, and the ratio of lift to drift istherefore the same as that of the cosine to the sine of the angle ofincidence. But in curved surfaces a very remarkable situation is found. The pressure, instead of being uniformly normal to the chord of thearc, is usually inclined considerably in front of the perpendicular. The result is that the lift is greater and the drift less than ifthe pressure were normal. Lilienthal was the first to discover thisexceedingly important fact, which is fully set forth in his book, BirdFlight the Basis of the Flying Art, but owing to some errors in themethods he used in making measurements, question was raised by otherinvestigators not only as to the accuracy of his figures, but even asto the existence of any tangential force at all. Our experiments confirmthe existence of this force, though our measurements differ considerablyfrom those of Lilienthal. While at Kitty Hawk we spent much time inmeasuring the horizontal pressure on our unloaded machine at variousangles of incidence. We found that at 13 degrees the horizontal pressurewas about 23 lbs. This included not only the drift proper, or horizontalcomponent of the pressure on the side of the surface, but also the headresistance of the framing as well. The weight of the machine at the timeof this test was about 108 lbs. Now, if the pressure had been normal tothe chord of the surface, the drift proper would have been to the lift(108 lbs. ) as the sine of 13 degrees is to the cosine of 13 degrees, or. 22 X 108/. 97 = 24+ lbs. ; but this slightly exceeds the total pullof 23 pounds on our scales. Therefore it is evident that the averagepressure on the surface, instead of being normal to the chord, was sofar inclined toward the front that all the head resistance of framingand wires used in the construction was more than overcome. In a wind offourteen miles per hour resistance is by no means a negligible factor, so that tangential is evidently a force of considerable value. In ahigher wind, which sustained the machine at an angle of 10 degrees thepull on the scales was 18 lbs. With the pressure normal to the chord thedrift proper would have been 17 X 98/. 98. The travel of the centre ofpressure made it necessary to put sand on the front rudder to bringthe centres of gravity and pressure into coincidence, consequently theweight of the machine varied from 98 lbs. To 108 lbs. In the differenttests= 17 lbs. , so that, although the higher wind velocity must havecaused an increase in the head resistance, the tangential force stillcame within 1 lb. Of overcoming it. After our return from Kitty Hawkwe began a series of experiments to accurately determine the amount anddirection of the pressure produced on curved surfaces when acted upon bywinds at the various angles from zero to 90 degrees. These experimentsare not yet concluded, but in general they support Lilienthal in theclaim that the curves give pressures more favourable in amount anddirection than planes; but we find marked differences in the exactvalues, especially at angles below 10 degrees. We were unable to obtaindirect measurements of the horizontal pressures of the machine withthe operator on board, but by comparing the distance travelled with thevertical fall, it was easily calculated that at a speed of 24 miles perhour the total horizontal resistances of our machine, when bearingthe operator, amounted to 40 lbs. , which is equivalent to about 2 1/3horse-power. It must not be supposed, however, that a motor developingthis power would be sufficient to drive a man-bearing machine. The extraweight of the motor would require either a larger machine, higher speed, or a greater angle of incidence in order to support it, and thereforemore power. It is probable, however, that an engine of 6 horse-power, weighing 100 lbs. Would answer the purpose. Such an engine is entirelypracticable. Indeed, working motors of one-half this weight perhorse-power (9 lbs. Per horse-power) have been constructed by severaldifferent builders. Increasing the speed of our machine from 24 to 33miles per hour reduced the total horizontal pressure from 40 to about 35lbs. This was quite an advantage in gliding, as it made it possible tosail about 15 per cent farther with a given drop. However, it wouldbe of little or no advantage in reducing the size of the motor ina power-driven machine, because the lessened thrust would becounterbalanced by the increased speed per minute. Some years agoProfessor Langley called attention to the great economy of thrust whichmight be obtained by using very high speeds, and from this many were ledto suppose that high speed was essential to success in a motor-drivenmachine. But the economy to which Professor Langley called attention wasin foot pounds per mile of travel, not in foot pounds per minute. Itis the foot pounds per minute that fixes the size of the motor. Theprobability is that the first flying machines will have a relatively lowspeed, perhaps not much exceeding 20 miles per hour, but the problem ofincreasing the speed will be much simpler in some respects than that ofincreasing the speed of a steamboat; for, whereas in the latter case thesize of the engine must increase as the cube of the speed, in the flyingmachine, until extremely high speeds are reached, the capacity of themotor increases in less than simple ratio; and there is even a decreasein the fuel per mile of travel. In other words, to double the speed ofa steamship (and the same is true of the balloon type of airship) eighttimes the engine and boiler capacity would be required, and four timesthe fuel consumption per mile of travel: while a flying machine wouldrequire engines of less than double the size, and there would be anactual decrease in the fuel consumption per mile of travel. But lookingat the matter conversely, the great disadvantage of the flying machineis apparent; for in the latter no flight at all is possible unless theproportion of horse-power to flying capacity is very high; but onthe other hand a steamship is a mechanical success if its ratio ofhorse-power to tonnage is insignificant. A flying machine that would flyat a speed of 50 miles per hour with engines of 1, 000 horse-power wouldnot be upheld by its wings at all at a speed of less than 25 milesan hour, and nothing less than 500 horse-power could drive it at thisspeed. But a boat which could make 40 miles an hour with engines of1, 000 horse-power would still move 4 miles an hour even if the engineswere reduced to 1 horse-power. The problems of land and water travelwere solved in the nineteenth century, because it was possible to beginwith small achievements, and gradually work up to our present success. The flying problem was left over to the twentieth century, because inthis case the art must be highly developed before any flight of anyconsiderable duration at all can be obtained. 'However, there is another way of flying which requires no artificialmotor, and many workers believe that success will come first by thisroad. I refer to the soaring flight, by which the machine is permanentlysustained in the air by the same means that are employed by soaringbirds. They spread their wings to the wind, and sail by the hour, with no perceptible exertion beyond that required to balance and steerthemselves. What sustains them is not definitely known, though it isalmost certain that it is a rising current of air. But whether it be arising current or something else, it is as well able to support aflying machine as a bird, if man once learns the art of utilising it. In gliding experiments it has long been known that the rate of verticaldescent is very much retarded, and the duration of the flight greatlyprolonged, if a strong wind blows UP the face of the hill parallelto its surface. Our machine, when gliding in still air, has a rate ofvertical descent of nearly 6 feet per second, while in a wind blowing26 miles per hour up a steep hill we made glides in which the rate ofdescent was less than 2 feet per second. And during the larger part ofthis time, while the machine remained exactly in the rising current, THERE WAS NO DESCENT AT ALL, BUT EVEN A SLIGHT RISE. If the operatorhad had sufficient skill to keep himself from passing beyond the risingcurrent he would have been sustained indefinitely at a higher point thanthat from which he started. The illustration shows one of these veryslow glides at a time when the machine was practically at a standstill. The failure to advance more rapidly caused the photographer some troublein aiming, as you will perceive. In looking at this picture you willreadily understand that the excitement of gliding experiments doesnot entirely cease with the breaking up of camp. In the photographicdark-room at home we pass moments of as thrilling interest as any inthe field, when the image begins to appear on the plate and it is yet anopen question whether we have a picture of a flying machine or merely apatch of open sky. These slow glides in rising current probably hold outgreater hope of extensive practice than any other method within man'sreach, but they have the disadvantage of requiring rather strong windsor very large supporting surfaces. However, when gliding operatorshave attained greater skill, they can with comparative safety maintainthemselves in the air for hours at a time in this way, and thus byconstant practice so increase their knowledge and skill that they canrise into the higher air and search out the currents which enable thesoaring birds to transport themselves to any desired point by firstrising in a circle and then sailing off at a descending angle. Thisillustration shows the machine, alone, flying in a wind of 35 miles perhour on the face of a steep hill, 100 feet high. It will be seenthat the machine not only pulls upward, but also pulls forward in thedirection from which the wind blows, thus overcoming both gravity andthe speed of the wind. We tried the same experiment with a man on it, but found danger that the forward pull would become so strong, that themen holding the ropes would be dragged from their insecure foothold onthe slope of the hill. So this form of experimenting was discontinuedafter four or five minutes' trial. 'In looking over our experiments of the past two years, with models andfull-size machines, the following points stand out with clearness:-- '1. That the lifting power of a large machine, held stationary in a windat a small distance from the earth, is much less than the Lilienthaltable and our own laboratory experiments would lead us to expect. Whenthe machine is moved through the air, as in gliding, the discrepancyseems much less marked. '2. That the ratio of drift to lift in well-shaped surfaces is less atangles of incidence of 5 degrees to 12 degrees than at an angle of 3degrees. '3. That in arched surfaces the centre of pressure at 90 degrees is nearthe centre of the surface, but moves slowly forward as the angle becomesless, till a critical angle varying with the shape and depth of thecurve is reached, after which it moves rapidly toward the rear till theangle of no lift is found. '4. That with similar conditions large surfaces may be controlled withnot much greater difficulty than small ones, if the control is effectedby manipulation of the surfaces themselves, rather than by a movement ofthe body of the operator. '5. That the head resistances of the framing can be brought to a pointmuch below that usually estimated as necessary. '6. That tails, both vertical and horizontal, may with safety beeliminated in gliding and other flying experiments. '7. That a horizontal position of the operator's body may be assumedwithout excessive danger, and thus the head resistance reduced to aboutone-fifth that of the upright position. '8. That a pair of superposed, or tandem surfaces, has less lift inproportion to drift than either surface separately, even after makingallowance for weight and head resistance of the connections. ' Thus, to the end of the 1901 experiments, Wilbur Wright provided afairly full account of what was accomplished; the record shows an amountof patient and painstaking work almost beyond belief--it was no questionof making a plane and launching it, but a business of trial and error, investigation and tabulation of detail, and the rejection time aftertime of previously accepted theories, till the brothers must have feltthe the solid earth was no longer secure, at times. Though it was Wilburwho set down this and other records of the work done, yet the actualwork was so much Orville's as his brother's that no analysis couldseparate any set of experiments and say that Orville did this and Wilburthat--the two were inseparable. On this point Griffith Brewer remarkedthat 'in the arguments, if one brother took one view, the other brothertook the opposite view as a matter of course, and the subject wasthrashed to pieces until a mutually acceptable result remained. I haveoften been asked since these pioneer days, "Tell me, Brewer, who wasreally the originator of those two?" In reply, I used first to say, "I think it was mostly Wilbur, " and later, when I came to know Orvillebetter, I said, "The thing could not have been without Orville. " Now, when asked, I have to say, "I don't know, " and I feel the more I thinkof it that it was only the wonderful combination of these two brothers, who devoted their lives together or this common object, that made thediscovery of the art of flying possible. ' Beyond the 1901 experiments in gliding, the record grows more scrappy, less detailed. It appears that once power-driven flight had beenachieved, the brothers were not so willing to talk as before;considering the amount of work that they put in, there could have beenlittle time for verbal description of that work--as already remarked, their tables still stand for the designer and experimenter. The end ofthe 1901 experiments left both brothers somewhat discouraged, thoughthey had accomplished more than any others. 'Having set out withabsolute faith in the existing scientific data, we ere driven to doubtone thing after another, finally, after two years of experiment, we castit all aside, and decided to rely entirely on our own investigations. Truth and error were everywhere so intimately mixed as to beindistinguishable.... We had taken up aeronautics as a sport. Wereluctantly entered upon the scientific side of it. ' Yet, driven thus to the more serious aspect of the work, they found inthe step its own reward, for the work of itself drew them on and on, tothe construction of measuring machines for the avoidance of error, andto the making of series after series of measurements, concerning whichWilbur wrote in 1908 (in the Century Magazine) that 'after makingpreliminary measurements on a great number of different shaped surfaces, to secure a general understanding of the subject, we began systematicmeasurements of standard surfaces, so varied in design as to bringout the underlying causes of differences noted in their pressures. Measurements were tabulated on nearly fifty of these at all angles fromzero to 45 degrees, at intervals of 2 1/2 degrees. Measurements werealso secured showing the effects on each other when surfaces aresuperposed, or when they follow one another. 'Some strange results were obtained. One surface, with a heavy roll atthe front edge, showed the same lift for all angles from 7 1/2 to 45degrees. This seemed so anomalous that we were almost ready to doubt ourown measurements, when a simple test was suggested. A weather vane, withtwo planes attached to the pointer at an angle of 80 degrees witheach other, was made. According to our table, such a vane would be inunstable equilibrium when pointing directly into the wind, for if bychance the wind should happen to strike one plane at 39 degrees and theother at 41 degrees, the plane with the smaller angle would have thegreater pressure and the pointer would be turned still farther outof the course of the wind until the two vanes again secured equalpressures, which would be at approximately 30 and 50 degrees. But thevane performed in this very manner. Further corroboration of the tableswas obtained in experiments with the new glider at Kill Devil Hill thenext season. 'In September and October, 1902 nearly 1, 000 gliding flights were made, several of which covered distances of over 600 feet. Some, made againsta wind of 36 miles an hour, gave proof of the effectiveness of thedevices for control. With this machine, in the autumn of 1903, we madea number of flights in which we remained in the air for over a minute, often soaring for a considerable time in one spot, without any descentat all. Little wonder that our unscientific assistant should think theonly thing needed to keep it indefinitely in the air would be a coat offeathers to make it light!' It was at the conclusion of these experiments of 1903 that the brothersconcluded they had obtained sufficient data from their thousands ofglides and multitude of calculations to permit of their constructingand making trial of a power-driven machine. The first designs got outprovided for a total weight of 600 lbs. , which was to include the weightof the motor and the pilot; but on completion it was found that therewas a surplus of power from the motor, and thus they had 150 lbs. Weightto allow for strengthening wings and other parts. They came up against the problem to which Riach has since devoted somuch attention, that of propeller design. 'We had thought of getting thetheory of the screw-propeller from the marine engineers, and then, byapplying our table of air-pressures to their formulae, of designingair-propellers suitable for our uses. But, so far as we could learn, themarine engineers possessed only empirical formulae, and the exact actionof the screw propeller, after a century of use, was still very obscure. As we were not in a position to undertake a long series of practicalexperiments to discover a propeller suitable for our machine, it seemednecessary to obtain such a thorough understanding of the theory of itsreactions as would enable us to design them from calculation alone. What at first seemed a simple problem became more complex the longer westudied it. With the machine moving forward, the air flying backward, the propellers turning sidewise, and nothing standing still, it seemedimpossible to find a starting point from which to trace the varioussimultaneous reactions. Contemplation of it was confusing. After longarguments we often found ourselves in the ludicrous position of eachhaving been converted to the other's side, with no more agreement thanwhen the discussion began. 'It was not till several months had passed, and every phase of theproblem had been thrashed over and over, that the various reactionsbegan to untangle themselves. When once a clear understanding had beenobtained there was no difficulty in designing a suitable propeller, withproper diameter, pitch, and area of blade, to meet the requirements ofthe flier. High efficiency in a screw-propeller is not dependent uponany particular or peculiar shape, and there is no such thing as a "best"screw. A propeller giving a high dynamic efficiency when used upon onemachine may be almost worthless when used upon another. The propellershould in every case be designed to meet the particular conditions ofthe machine to which it is to be applied. Our first propellers, builtentirely from calculation, gave in useful work 66 per cent of the powerexpended. This was about one-third more than had been secured by Maximor Langley. ' Langley had made his last attempt with the 'aerodrome, ' and his splendidfailure but a few days before the brothers made their first attempt atpower-driven aeroplane flight. On December 17th, 1903, the machine wastaken out; in addition to Wilbur and Orville Wright, there were presentfive spectators: Mr A. D. Etheridge, of the Kill Devil life-savingstation; Mr W. S. Dough, Mr W. C. Brinkley, of Manteo; Mr John Ward, ofNaghead, and Mr John T. Daniels. [*] A general invitation had been givento practically all the residents in the vicinity, but the Kill Devildistrict is a cold area in December, and history had recorded so manyexperiments in which machines had failed to leave the ground thatbetween temperature and scepticism only these five risked a waste oftheir time. [*] This list is as given by Wilbur Wright himself. And these five were in at the greatest conquest man had made since JamesWatt evolved the steam engine--perhaps even a greater conquest than thatof Watt. Four flights in all were made; the first lasted only twelveseconds, 'the first in the history of the world in which a machinecarrying a man had raised itself into the air by its own power in freeflight, had sailed forward on a level course without reduction ofspeed, and had finally landed without being wrecked, ' said WilburWright concerning the achievement. [*] The next two flights were slightlylonger, and the fourth and last of the day was one second short of thecomplete minute; it was made into the teeth of a 20 mile an hour wind, and the distance travelled was 852 feet. [*] Century Magazine, September, 1908. This bald statement of the day's doings is as Wilbur Wright himselfhas given it, and there is in truth nothing more to say; no amount ofstatement could add to the importance of the achievement, and no morethan the bare record is necessary. The faith that had inspired the longroll of pioneers, from da Vinci onward, was justified at last. Having made their conquest, the brothers took the machine back to camp, and, as they thought, placed it in safety. Talking with the little groupof spectators about the flights, they forgot about the machine, and thena sudden gust of wind struck it. Seeing that it was being overturned, all made a rush toward it to save it, and Mr Daniels, a man of largeproportions, was in some way lifted off his feet, falling between theplanes. The machine overturned fully, and Daniels was shaken like a diein a cup as the wind rolled the machine over and over--he came out atthe end of his experience with a series of bad bruises, and no more, butthe damage done to the machine by the accident was sufficient to renderit useless for further experiment that season. A new machine, stronger and heavier, was constructed by the brothers, and in the spring of 1904 they began experiments again at SimsStation, eight miles to the east of Dayton, their home town. Pressrepresentatives were invited for the first trial, and about a dozencame--the whole gathering did not number more than fifty people. 'Whenpreparations had been concluded, ' Wilbur Wright wrote of this trial, 'awind of only three or four miles an hour was blowing--insufficient forstarting on so short a track--but since many had come a long way tosee the machine in action, an attempt was made. To add to the otherdifficulty, the engine refused to work properly. The machine, afterrunning the length of the track, slid off the end without rising intothe air at all. Several of the newspaper men returned next day but wereagain disappointed. The engine performed badly, and after a glide ofonly sixty feet the machine again came to the ground. Further trial waspostponed till the motor could be put in better running condition. Thereporters had now, no doubt, lost confidence in the machine, thoughtheir reports, in kindness, concealed it. Later, when they heard thatwe were making flights of several minutes' duration, knowing that longerflights had been made with airships, and not knowing any essentialdifference between airships and flying machines, they were but littleinterested. 'We had not been flying long in 1904 before we found that the problem ofequilibrium had not as yet been entirely solved. Sometimes, in makinga circle, the machine would turn over sidewise despite anything theoperator could do, although, under the same conditions in ordinarystraight flight it could have been righted in an instant. In one flight, in 1905, while circling round a honey locust-tree at a height of about50 feet, the machine suddenly began to turn up on one wing, and took acourse toward the tree. The operator, not relishing the idea of landingin a thorn tree, attempted to reach the ground. The left wing, however, struck the tree at a height of 10 or 12 feet from the ground and carriedaway several branches; but the flight, which had already covered adistance of six miles, was continued to the starting point. 'The causes of these troubles--too technical for explanation here--werenot entirely overcome till the end of September, 1905. The flights thenrapidly increased in length, till experiments were discontinued afterOctober 5 on account of the number of people attracted to the field. Although made on a ground open on every side, and bordered on two sidesby much-travelled thoroughfares, with electric cars passing every hour, and seen by all the people living in the neighbourhood for miles around, and by several hundred others, yet these flights have been made by somenewspapers the subject of a great "mystery. "' Viewing their work from the financial side, the two brothers incurredbut little expense in the earlier gliding experiments, and, indeed, viewed these only as recreation, limiting their expenditure to thatwhich two men might spend on any hobby. When they had once achievedsuccessful power-driven flight, they saw the possibilities of theirwork, and abandoned such other business as had engaged their energies, sinking all their capital in the development of a practical flyingmachine. Having, in 1905, improved their designs to such an extent thatthey could consider their machine a practical aeroplane, they devotedthe years 1906 and 1907 to business negotiations and to the constructionof new machines, resuming flying experiments in May of 1908 in order totest the ability of their machine to meet the requirements of a contractthey had made with the United States Government, which required anaeroplane capable of carrying two men, together with sufficient fuelsupplies for a flight of 125 miles at 40 miles per hour. Practicallysimilar to the machine used in the experiments of 1905, the contractaeroplane was fitted with a larger motor, and provision was made forseating a passenger and also for allowing of the operator assuming asitting position, instead of lying prone. Before leaving the work of the brothers to consider contemporary events, it may be noted that they claimed--with justice--that they were first toconstruct wings adjustable to different angles of incidence on the rightand left side in order to control the balance of an aeroplane; thefirst to attain lateral balance by adjusting wing-tips to respectivelydifferent angles of incidence on the right and left sides, and the firstto use a vertical vane in combination with wing-tips, adjustable torespectively different angles of incidence, in balancing and steeringan aeroplane. They were first, too, to use a movable vertical tail, incombination with wings adjustable to different angles of incidence, incontrolling the balance and direction of an aeroplane. [*] [*]Aeronautical Journal, No. 79. A certain Henry M. Weaver, who went to see the work of the brothers, writing in a letter which was subsequently read before the Aero Club deFrance records that he had a talk in 1905 with the farmer who rented thefield in which the Wrights made their flights. ' On October 5th (1905) hewas cutting corn in the next field east, which is higher ground. Whenhe noticed the aeroplane had started on its flight he remarked to hishelper: "Well, the boys are at it again, " and kept on cutting corn, atthe same time keeping an eye on the great white form rushing about itscourse. "I just kept on shocking corn, " he continued, "until I got downto the fence, and the durned thing was still going round. I thought itwould never stop. "' He was right. The brothers started it, and it will never stop. Mr Weaver also notes briefly the construction of the 1905 Wright flier. 'The frame was made of larch wood-from tip to tip of the wings thedimension was 40 feet. The gasoline motor--a special constructionmade by them--much the same, though, as the motor on the Pope-Toledoautomobile--was of from 12 to 15 horse-power. The motor weighed 240 lbs. The frame was covered with ordinary muslin of good quality. No attemptwas made to lighten the machine; they simply built it strong enoughto stand the shocks. The structure stood on skids or runners, like asleigh. These held the frame high enough from the ground in alightingto protect the blades of the propeller. Complete with motor, the machineweighed 925 lbs. XII. THE FIRST YEARS OF CONQUEST It is no derogation of the work accomplished by the Wright Brothers tosay that they won the honour of the first power-propelled flights ina heavier-than-air machine only by a short period. In Europe, andespecially in France, independent experiment was being conducted byFerber, by Santos-Dumont, and others, while in England Cody was not farbehind the other giants of those days. The history of the early yearsof controlled power flights is a tangle of half-records; there were nochroniclers, only workers, and much of what was done goes unrecordedperforce, since it was not set down at the time. Before passing to survey of those early years, let it be set down thatin 1907, when the Wright Brothers had proved the practicability of theirmachines, negotiations were entered into between the brothers andthe British War office. On April 12th 1907, the apostle of militarystagnation, Haldane, then War Minister, put an end to the negotiationsby declaring that 'the War office is not disposed to enter intorelations at present with any manufacturer of aeroplanes' The stateof the British air service in 1914 at the outbreak of hostilities, iseloquent regarding the pursuance of the policy which Haldane initiated. 'If I talked a lot, ' said Wilbur Wright once, 'I should be like theparrot, which is the bird that speaks most and flies least. ' Thatattitude is emblematic of the majority of the early fliers, and becauseof it the record of their achievements is incomplete to-day. Ferber, for instance, has left little from which to state what he did, and thatlittle is scattered through various periodicals, scrappily enough. AFrench army officer, Captain Ferber was experimenting with monoplaneand biplane gliders at the beginning of the century-his work wascontemporary with that of the Wrights. He corresponded both with Chanuteand with the Wrights, and in the end he was commissioned by theFrench Ministry of War to undertake the journey to America in orderto negotiate with the Wright Brothers concerning French rights in thepatents they had acquired, and to study their work at first hand. Ferber's experiments in gliding began in 1899 at the Military School atFountainebleau, with a canvas glider of some 80 square feet supportingsurface, and weighing 65 lbs. Two years later he constructed a largerand more satisfactory machine, with which he made numerous excellentglides. Later, he constructed an apparatus which suspended a plane froma long arm which swung on a tower, in order that experiments might becarried out without risk to the experimenter, and it was not until 1905that he attempted power-driven free flight. He took up the Voisin designof biplane for his power-driven flights, and virtually devoted all hisenergies to the study of aeronautics. His book, Aviation, its Dawnand Development, is a work of scientific value--unlike many of hiscontemporaries, Ferber brought to the study of the problems of flight atrained mind, and he was concerned equally with the theoretical problemsof aeronautics and the practical aspects of the subject. After Bleriot's successful cross-Channel flight, it was proposed tooffer a prize of L1, 000 for the feat which C. S. Rolls subsequentlyaccomplished (starting from the English side of the Channel), a flightfrom Boulogne to Dover and back; in place of this, however, an aviationweek at Boulogne was organised, but, although numerous aviators wereinvited to compete, the condition of the flying grounds was such thatno competitions took place. Ferber was virtually the only one to do anyflying at Boulogne, and at the outset he had his first accident; afterwhat was for those days a good flight, he made a series of circleswith his machine, when it suddenly struck the ground, being partiallywrecked. Repairs were carried out, and Ferber resumed his exhibitionflights, carrying on up to Wednesday, September 22nd, 1909. On that dayhe remained in the air for half an hour, and, as he was about to land, the machine struck a mound of earth and overturned, pinning Ferber underthe weight of the motor. After being extricated, Ferber seemed to showlittle concern at the accident, but in a few minutes he complained ofgreat pain, when he was conveyed to the ambulance shed on the ground. 'I was foolish, ' he told those who were with him there. 'I was flyingtoo low. It was my own fault and it will be a severe lesson to me. I wanted to turn round, and was only five metres from the ground. ' Alittle after this, he got up from the couch on which he had been placed, and almost immediately collapsed, dying five minutes later. Ferber's chief contemporaries in France were Santos-Dumont, of airshipfame, Henri and Maurice Farman, Hubert Latham, Ernest Archdeacon, andDelagrange. These are names that come at once to mind, as does that ofBleriot, who accomplished the second great feat of power-driven flight, but as a matter of fact the years 1903-10 are filled with a little hostof investigators and experimenters, many of whom, although their namesdo not survive to any extent, are but a very little way behind thosementioned here in enthusiasm and devotion. Archdeacon and GabrielVoisin, the former of whom took to heart the success achieved by theWright Brothers, co-operated in experiments in gliding. Archdeaconconstructed a glider in box-kite fashion, and Voisin experimented withit on the Seine, the glider being towed by a motorboat to attain thenecessary speed. It was Archdeacon who offered a cup for the firststraight flight of 200 metres, which was won by Santos-Dumont, and healso combined with Henri Deutsch de la Meurthe in giving the prize forthe first circular flight of a mile, which was won by Henry Farman onJanuary 13th, 1908. A history of the development of aviation in France in these, thestrenuous years, would fill volumes in itself. Bleriot was carryingout experiments with a biplane glider on the Seine, and RobertEsnault-Pelterie was working on the lines of the Wright Brothers, bringing American practice to France. In America others besides theWrights had wakened to the possibilities of heavier-than-air flight;Glenn Curtiss, in company with Dr Alexander Graham Bell, with J. A. D. McCurdy, and with F. W. Baldwin, a Canadian engineer, formed the AerialExperiment Company, which built a number of aeroplanes, most famous ofwhich were the 'June Bug, ' the 'Red Wing, ' and the 'White Wing. ' In 1908the 'June Bug 'won a cup presented by the Scientific American--it wasthe first prize offered in America in connection with aeroplane flight. Among the little group of French experimenters in these first years ofpractical flight, Santos-Dumont takes high rank. He built his 'No. 14bis' aeroplane in biplane form, with two superposed main plane surfaces, and fitted it with an eight-cylinder Antoinette motor driving atwo-bladed aluminium propeller, of which the blades were 6 feet onlyfrom tip to tip. The total lift surface of 860 square feet was givenwith a wing-span of a little under 40 feet, and the weight of thecomplete machine was 353 lbs. , of which the engine weighed 158 lbs. In July of 1906 Santos-Dumont flew a distance of a few yards in thismachine, but damaged it in striking the ground; on October 23rd of thesame year he made a flight of nearly 200 feet--which might have beenlonger, but that he feared a crowd in front of the aeroplane and cutoff his ignition. This may be regarded as the first effective flight inEurope, and by it Santos-Dumont takes his place as one of the chief--ifnot the chief--of the pioneers of the first years of practical flight, so far as Europe is concerned. Meanwhile, the Voisin Brothers, who in 1904 made cellular kites forArchdeacon to test by towing on the Seine from a motor launch, obtaineddata for the construction of the aeroplane which Delagrange and HenryFarman were to use later. The Voisin was a biplane, constructed withdue regard to the designs of Langley, Lilienthal, and other earlierexperimenters--both the Voisins and M. Colliex, their engineer, studiedLilienthal pretty exhaustively in getting out their design, though theirown researches were very thorough as well. The weight of this Voisinbiplane was about 1, 450 lbs. , and its maximum speed was some 38 to 40miles per hour, the total supporting surface being about 535 squarefeet. It differed from the Wright design in the possession of atail-piece, a characteristic which marked all the French school of earlydesign as in opposition to the American. The Wright machine got itslongitudinal stability by means of the main planes and the elevatingplanes, while the Voisin type added a third factor of stability in itssailplanes. Further, the Voisins fitted their biplane with a wheeledundercarriage, while the Wright machine, being fitted only with runners, demanded a launching rail for starting. Whether a machine should betailless or tailed was for some long time matter for acute controversy, which in the end was settled by the fitting of a tail to the Wrightmachines-France won the dispute by the concession. Henry Farman, who began his flying career with a Voisin machine, evolvedfrom it the aeroplane which bore his name, following the main lines ofthe Voisin type fairly closely, but making alterations in the controls, and in the design of the undercarriage, which was somewhat elaborated, even to the inclusion of shock absorbers. The seven-cylinder 50horse-power Gnome rotary engine was fitted to the Farman machine--theVoisins had fitted an eight-cylinder Antoinette, giving 50 horse-powerat 1, 100 revolutions per minute, with direct drive to the propeller. Farman reduced the weight of the machine from the 1, 450 lbs. Of theVoisins to some 1, 010 lbs. Or thereabouts, and the supporting area to450 square feet. This machine won its chief fame with Paulhan as pilotin the famous London to Manchester flight--it is to be remarked, too, that Farman himself was the first man in Europe to accomplish a flightof a mile. Other notable designs of these early days were the 'R. E. P. ', EsnaultPelterie's machine, and the Curtiss-Herring biplane. Of these EsnaultPelterie's was a monoplane, designed in that form since Esnault Pelteriehad found by experiment that the wire used in bracing offers far moreresistance to the air than its dimensions would seem to warrant. Hebuilt the wings of sufficient strength to stand the strain of flightwithout bracing wires, and dependent only for their support on thepoints of attachment to the body of the machine; for the rest, itcarried its propeller in front of the planes, and both horizontal andvertical rudders at the stern--a distinct departure from the Wrightand similar types. One wheel only was fixed under the body where theundercarriage exists on a normal design, but light wheels were fixed, one at the extremity of each wing, and there was also a wheel under thetail portion of the machine. A single lever actuated all the controlsfor steering. With a supporting surface of 150 square feet the machineweighed 946 lbs. , about 6. 4 lbs. Per square foot of lifting surface. The Curtiss biplane, as flown by Glenn Curtiss at the Rheims meeting, was built with a bamboo framework, stayed by means of very finesteel-stranded cables. A--then--novel feature of the machine was themoving of the ailerons by the pilot leaning to one side or the other inhis seat, a light, tubular arm-rest being pressed by his body when heleaned to one side or the other, and thus operating the movement of theailerons employed for tilting the plane when turning. A steering-wheelfitted immediately in front of the pilot's seat served to operate a rearsteering-rudder when the wheel was turned in either direction, whilepulling back the wheel altered the inclination of the front elevatingplanes, and so gave lifting or depressing control of the plane. This machine ran on three wheels before leaving the ground, a centralundercarriage wheel being fitted in front, with two more in line witha right angle line drawn through the centre of the engine crank at therear end of the crank-case. The engine was a 35 horsepower Vee design, water cooled, with overhead inlet and exhaust valves, and Boschhigh-tension magneto ignition. The total weight of the plane in flyingorder was about 700 lbs. As great a figure in the early days as either Ferber or Santos-Dumontwas Louis Bleriot, who, as early as 1900 built a flapping-wing model, this before ever he came to experimenting with the Voisin biplane typeof glider on the Seine. Up to 1906 he had built four biplanes of his owndesign, and in March of 1907 he built his first monoplane, to wreckit only a few days after completion in an accident from which he hada fortunate escape. His next machine was a double monoplane, designedafter Langley's precept, to a certain extent, and this was totallywrecked in September of 1907. His seventh machine, a monoplane, wasbuilt within a month of this accident, and with this he had a numberof mishaps, also achieving some good flights, including one in whichhe made a turn. It was wrecked in December of 1907, whereupon he builtanother monoplane on which, on July 6th, 1908, Bleriot made a flightlasting eight and a half minutes. In October of that year he flew themachine from Toury to Artenay and returned on it--this was just a dayafter Farman's first cross-country flight--but, trying to repeat thesuccess five days later, Bleriot collided with a tree in a fog andwrecked the machine past repair. Thereupon he set about building hiseleventh machine, with which he was to achieve the first flight acrossthe English channel. Henry Farman, to whom reference has already been made, was engaged withhis two brothers, Maurice and Richard, in the motor-car business, andturned to active interest in flying in 1907, when the Voisin firm builthis first biplane on the box-kite principle. In July of 1908 he wona prize of L400 for a flight of thirteen miles, previously havingcompleted the first kilometre flown in Europe with a passenger, the saidpassenger being Ernest Archdeaon. In September of 1908 Farman put up aspeed record of forty miles an hour in a flight lasting forty minutes. Santos-Dumont produced the famous 'Demoiselle' monoplane early in 1909, a tiny machine in which the pilot had his seat in a sort of miniaturecage under the main plane. It was a very fast, light little machine butwas difficult to fly, and owing to its small wingspread was unableto glide at a reasonably safe angle. There has probably never been acheaper flying machine to build than the 'Demoiselle, ' which could be soupset as to seem completely wrecked, and then repaired ready for furtherflight by a couple of hours' work. Santos-Dumont retained no patentin the design, but gave it out freely to any one who chose to build'Demoiselles'; the vogue of the pattern was brief, owing to thedifficulty of piloting the machine. These were the years of records, broken almost as soon as made. Therewas Farman's mile, there was the flight of the Comte de Lambert over theEiffel Tower, Latham's flight at Blackpool in a high wind, the Rheimsrecords, and then Henry Farman's flight of four hours later in 1909, Orville Wright's height record of 1, 640 feet, and Delagrange's speedrecord of 49. 9 miles per hour. The coming to fame of the Gnome rotaryengine helped in the making of these records to a very great extent, for in this engine was a prime mover which gave the reliability thataeroplane builders and pilots had been searching for, but vainly. TheWrights and Glenn Curtiss, of course, had their own designs of engine, but the Gnome, in spite of its lack of economy in fuel and oil, and itshigh cost, soon came to be regarded as the best power plant for flight. Delagrange, one of the very good pilots of the early days, provided acurious insight to the way in which flying was regarded, at the openingof the Juvisy aero aerodrome in May of 1909. A huge crowd had gatheredfor the first day's flying, and nine machines were announced to appear, but only three were brought out. Delagrange made what was considered anindifferent little flight, and another pilot, one De Bischoff, attemptedto rise, but could not get his machine off the ground. Thereupon thecrowd of 30, 000 people lost their tempers, broke down the barrierssurrounding the flying course, and hissed the officials, who were quiteunable to maintain order. Delagrange, however, saved the situationby making a circuit of the course at a height of thirty feet from theground, which won him rounds of cheering and restored the crowd togood humour. Possibly the smash achieved by Rougier, the famous racingmotorist, who crashed his Voisin biplane after Delagrange had made hiscircuit, completed the enjoyment of the spectators. Delagrange, flyingat Argentan in June of 1909, made a flight of four kilometres at aheight of sixty feet; for those days this was a noteworthy performance. Contemporary with this was Hubert Latham's flight of an hour and sevenminutes on an Antoinette monoplane; this won the adjective 'magnificent'from contemporary recorders of aviation. Viewing the work of the little group of French experimenters, it is, at this length of time from their exploits, difficult to see whythey carried the art as far as they did. There was in it little ofsatisfaction, a certain measure of fame, and practically no profit--thegiants of those days got very little for their pains. Delagrange'sexperience at the opening of the Juvisy ground was symptomatic of theway in which flight was regarded by the great mass of people--it was asport, and nothing more, but a sport without the dividends attachingto professional football or horse-racing. For a brief period, after theRheims meeting, there was a golden harvest to be reaped by the best ofthe pilots. Henry Farman asked L2, 000 for a week's exhibition flying inEngland, and Paulhan asked half that sum, but a rapid increase inthe number of capable pilots, together with the fact that most flyingmeetings were financial failures, owing to great expense in organisationand the doubtful factor of the weather, killed this goose before manygolden eggs had been gathered in by the star aviators. Besides, asheight and distance records were broken one after another, it becameless and less necessary to pay for entrance to an aerodrome in order tosee a flight--the thing grew too big for a mere sports ground. Long before Rheims and the meeting there, aviation had grown too big forthe chronicling of every individual effort. In that period of the firstdays of conquest of the air, so much was done by so many whose namesare now half-forgotten that it is possible only to pick out the greatfigures and make brief reference to their achievements and the machineswith which they accomplished so much, pausing to note such epoch-makingevents as the London-Manchester flight, Bleriot's Channel crossing, and the Rheims meeting itself, and then passing on beyond the days ofindividual records to the time when the machine began to dominate theman. This latter because, in the early days, it was heroism to trustlife to the planes that were turned out--the 'Demoiselle' and theAntoinette machine that Latham used in his attempt to fly the Channelare good examples of the flimsiness of early types--while in the laterperiod, that of the war and subsequently, the heroism turned itself in adifferent--and nobler-direction. Design became standardised, thoughnot perfected. The domination of the machine may best be expressed bycontrasting the way in which machines came to be regarded as comparedwith the men who flew them: up to 1909, flying enthusiasts talked ofFarman, of Bleriot, of Paulhan, Curtiss, and of other men; later, theybegan to talk of the Voisin, the Deperdussin, and even to the Fokker, the Avro, and the Bristol type. With the standardising of the machine, the days of the giants came to an end. XIII. FIRST FLIERS IN ENGLAND Certain experiments made in England by Mr Phillips seem to have comenear robbing the Wright Brothers of the honour of the first flight;notes made by Colonel J. D. Fullerton on the Phillips flying machineshow that in 1893 the first machine was built with a length of 25 feet, breadth of 22 feet, and height of 11 feet, the total weight, including a72 lb. Load, being 420 lbs. The machine was fitted with some fifty woodslats, in place of the single supporting surface of the monoplane or twosuperposed surfaces of the biplane, these slats being fixed in a steelframe so that the whole machine rather resembled a Venetian blind. Asteam engine giving about 9 horse-power provided the motive power forthe six-foot diameter propeller which drove the machine. As it wasnot possible to put a passenger in control as pilot, the machine wasattached to a central post by wire guys and run round a circle 100feet in diameter, the track consisting of wooden planking 4 feet wide. Pressure of air under the slats caused the machine to rise some two orthree feet above the track when sufficient velocity had been attained, and the best trials were made on June 19th 1893, when at a speed of 40miles an hour, with a total load of 385 lbs. , all the wheels were offthe ground for a distance of 2, 000 feet. In 1904 a full-sized machine was constructed by Mr Phillips, with atotal weight, including that of the pilot, of 600 lbs. The machine wasdesigned to lift when it had attained a velocity of 50 feet persecond, the motor fitted giving 22 horse-power. On trial, however, thelongitudinal equilibrium was found to be defective, and a further designwas got out, the third machine being completed in 1907. In this the woodslats were held in four parallel container frames, the weight of themachine, excluding the pilot, being 500 lbs. A motor similar to thatused in the 1904 machine was fitted, and the machine was designed tolift at a velocity of about 30 miles an hour, a seven-foot propellerdoing the driving. Mr Phillips tried out this machine in a field about400 yards across. 'The machine was started close to the hedge, and rosefrom the ground when about 200 yards had been covered. When the machinetouched the ground again, about which there could be no doubt, owing tothe terrific jolting, it did not run many yards. When it came to rest Iwas about ten yards from the boundary. Of course, I stopped the enginebefore I commenced to descend. '[*] [*] Aeronautical Journal, July, 1908. S. F. Cody, an American by birth, aroused the attention not only of theBritish public, but of the War office and Admiralty as well, as early as1905 with his man-lifting kites. In that year a height of 1, 600 feet wasreached by one of these box-kites, carrying a man, and later in the sameyear one Sapper Moreton, of the Balloon Section of the Royal Engineers(the parent of the Royal Flying Corps) remained for an hour at analtitude of 2, 600 feet. Following on the success of these kites, Codyconstructed an aeroplane which he designated a 'power kite, ' whichwas in reality a biplane that made the first flight in Great Britain. Speaking before the Aeronautical Society in 1908, Cody said that 'I haveaccomplished one thing that I hoped for very much, that is, to be thefirst man to fly in Great Britain.... I made a machine that left theground the first time out; not high, possibly five or six inches only. Imight have gone higher if I wished. I made some five flights in all, andthe last flight came to grief.... On the morning of the accident Iwent out after adjusting my propellers at 8 feet pitch running at 600(revolutions per minute). I think that I flew at about twenty-eightmiles per hour. I had 50 horsepower motor power in the engine. A bunchof trees, a flat common above these trees, and from this flat there is aslope goes down... To another clump of trees. Now, these clumps of treesare a quarter of a mile apart or thereabouts.... I was accused of doingnothing but jumping with my machine, so I got a bit agitated and went tofly. I went out this morning with an easterly wind, and left the ground atthe bottom of the hill and struck the ground at the top, a distance of74 yards. That proved beyond a doubt that the machine would fly--itflew uphill. That was the most talented flight the machine did, in myopinion. Now, I turned round at the top and started the machine and leftthe ground--remember, a ten mile wind was blowing at the time. Then, 60yards from where the men let go, the machine went off in this direction(demonstrating)--I make a line now where I hoped to land--to cut thesetrees off at that side and land right off in here. I got here somewhatexcited, and started down and saw these trees right in front of me. Idid not want to smash my head rudder to pieces, so I raised it again andwent up. I got one wing direct over that clump of trees, the right wingover the trees, the left wing free; the wind, blowing with me, had tolift over these trees. So I consequently got a false lift on the rightside and no lift on the left side. Being only about 8 feet from thetree tops, that turned my machine up like that (demonstrating). Thisend struck the ground shortly after I had passed the trees. I pulled thesteering handle over as far as I could. Then I faced another bunch oftrees right in front of me. Trying to avoid this second bunch of trees Iturned the rudder, and turned it rather sharp. That side of the machinestruck, and it crumpled up like so much tissue paper, and the machinespun round and struck the ground that way on, and the framework wasconsiderably wrecked. Now, I want to advise all aviators not to tryto fly with the wind and to cross over any big clump of earth or anyobstacle of any description unless they go square over the top of it, because the lift is enormous crossing over anything like that, and incoming the other way against the wind it would be the same thing whenyou arrive at the windward side of the obstacle. That is a point I didnot think of, and had I thought of it I would have been more cautious. ' This Cody machine was a biplane with about 40 foot span, the wings beingabout 7 feet in depth with about 8 feet between upper and lower wingsurfaces. 'Attached to the extremities of the lower planes are two smallhorizontal planes or rudders, while a third small vertical plane isfixed over the centre of the upper plane. ' The tail-piece and principalrudder were fitted behind the main body of the machine, and a horizontalrudder plane was rigged out in front, on two supporting arms extendingfrom the centre of the machine. The small end-planes and the verticalplane were used in conjunction with the main rudder when turning toright or left, the inner plane being depressed on the turn, and theouter one correspondingly raised, while the vertical plane, working inconjunction, assisted in preserving stability. Two two-bladed propellerswere driven by an eight-cylinder 50 horse-power Antoinette motor. Withthis machine Cody made his first flights over Laffan's plain, being thendefinitely attached to the Balloon Section of the Royal Engineers asmilitary aviation specialist. There were many months of experiment and trial, after the accident whichCody detailed in the statement given above, and then, on May 14th, 1909, Cody took the air and made a flight of 1, 200 yards with entire success. Meanwhile A. V. Roe was experimenting at Lea Marshes with a triplaneof rather curious design the pilot having his seat between two sets ofthree superposed planes, of which the front planes could be tilted andtwisted while the machine was in motion. He comes but a little way afterCody in the chronology of early British experimenters, but Cody, a borninventor, must be regarded as the pioneer of the present century sofar as Britain is concerned. He was neither engineer nor trainedmathematician, but he was a good rule-of-thumb mechanic and a man ofpluck and perseverance; he never strove to fly on an imperfect machine, but made alteration after alteration in order to find out what wasimprovement and what was not, in consequence of which it was said of himthat he was 'always satisfied with his alterations. ' By July of 1909 he had fitted an 80 horse-power motor to his biplane, and with this he made a flight of over four miles over Laffan's Plain onJuly 21st. By August he was carrying passengers, the first being ColonelCapper of the R. E. Balloon Section, who flew with Cody for overtwo miles, and on September 8th, 1909, he made a world's recordcross-country flight of over forty miles in sixty-six minutes, takinga course from Laffan's Plain over Farnborough, Rushmoor, and Fleet, and back to Laffan's Plain. He was one of the competitors in the 1909Doncaster Aviation Meeting, and in 1910 he competed at Wolverhampton, Bournemouth, and Lanark. It was on June 7th, 1910, that he qualified forhis brevet, No. 9, on the Cody biplane. He built a machine which embodied all the improvements for which he hadgained experience, in 1911, a biplane with a length of 35 feet andspan of 43 feet, known as the 'Cody cathedral' on account of itsrather cumbrous appearance. With this, in 1911, he won the two Michelintrophies presented in England, completed the Daily Mail circuit ofBritain, won the Michelin cross-country prize in 1912 and altogether, bythe end of 1912, had covered more than 7, 000 miles with the machine. It was fitted with a 120 horse-power Austro-Daimler engine, and wascharacterised by an exceptionally wide range of speed--the greatwingspread gave a slow landing speed. A few of his records may be given: in 1910, flying at Laffan's Plain inhis biplane, fitted with a 50-60 horsepower Green engine, on December31st, he broke the records for distance and time by flying 185 miles, 787 yards, in 4 hours 37 minutes. On October 31st, 1911, he beat thisrecord by flying for 5 hours 15 minutes, in which period he covered261 miles 810 yards with a 60 horse-power Green engine fitted to hisbiplane. In 1912, competing in the British War office tests of militaryaeroplanes, he won the L5, 000 offered by the War Office. This was incompetition with no less than twenty-five other machines, among whichwere the since-famous Deperdussin, Bristol, Flanders, and Avro types, as well as the Maurice Farman and Bleriot makes of machine. Cody'sremarkable speed range was demonstrated in these trials, the speeds ofhis machine varying between 72. 4 and 48. 5 miles per hour. The machinewas the only one delivered for the trials by air, and during the threehours' test imposed on all competitors a maximum height of 5, 000 feetwas reached, the first thousand feet being achieved in three and a halfminutes. During the summer of 1913 Cody put his energies into the production ofa large hydro-biplane, with which he intended to win the L5, 000 prizeoffered by the Daily Mail to the first aviator to fly round Britain ona waterplane. This machine was fitted with landing gear for its tests, and, while flying it over Laffan's Plain on August 7th, 1913, with Mr W. H. B. Evans as passenger, Cody met with the accident that cost bothhim and his passenger their lives. Aviation lost a great figure by hisdeath, for his plodding, experimenting, and dogged courage not only wonhim the fame that came to a few of the pilots of those days, but alsoadvanced the cause of flying very considerably and contributed not alittle to the sum of knowledge in regard to design and construction. Another figure of the early days was A. V. Roe, who came from marineengineering to the motor industry and aviation in 1905. In 1906 he wentout to Colorado, getting out drawings for the Davidson helicopter, andin 1907 having returned to England, he obtained highest award out of 200entries in a model aeroplane flying competition. From the design ofthis model he built a full-sized machine, and made a first flight on it, fitted with a 24 horse-power Antoinette engine, in June of 1908 Later, he fitted a 9 horsepower motor-cycle engine to a triplane of his owndesign, and with this made a number of short flights; he got his flyingbrevet on a triplane with a motor of 35 horse-power, which, togetherwith a second triplane, was entered for the Blackpool aviation meetingof 1910 but was burnt in transport to the meeting. He was responsiblefor the building of the first seaplane to rise from English waters, andmay be counted the pioneer of the tractor type of biplane. In 1913 hebuilt a two-seater tractor biplane with 80 horse-power engine, a machinewhich for some considerable time ranked as a leader of design. Togetherwith E. V. Roe and H. V. Roe, 'A. V. ' controlled the Avro works, whichproduced some of the most famous training machines of the war period ina modification of the original 80 horse-power tractor. The first of theseries of Avro tractors to be adopted by the military authorities wasthe 1912 biplane, a two-seater fitted with 50 horsepower engine. It wasthe first tractor biplane with a closed fuselage to be used for militarywork, and became standard for the type. The Avro seaplane, of I 100horse-power (a fourteen-cylinder Gnome engine was used) was taken upby the British Admiralty in 1913. It had a length of 34 feet and awing-span of 50 feet, and was of the twin-float type. Geoffrey de Havilland, though of later rank, counts high among designersof British machines. He qualified for his brevet as late as February, 1911, on a biplane of his own construction, and became responsible forthe design of the BE2, the first successful British Government biplane. On this he made a British height record of 10, 500 feet over SalisburyPlain, in August of 1912, when he took up Major Sykes as passenger. Inthe war period he was one of the principal designers of fighting andreconnaissance machines. F. Handley Page, who started in business as an aeroplane builder in1908, having works at Barking, was one of the principal exponents ofthe inherently stable machine, to which he devoted practically all hisexperimental work up to the outbreak of war. The experiments were madewith various machines, both of monoplane and biplane type, and of theseone of the best was a two-seater monoplane built in 1911, while a secondwas a larger machine, a biplane, built in 1913 and fitted with a 110horse-power Anzani engine. The war period brought out the giant biplanewith which the name of Handley Page is most associated, the twin-enginednight-bomber being a familiar feature of the later days of the war;the four-engined bomber had hardly had a chance of proving itself underservice conditions when the war came to an end. Another notable figure of the early period was 'Tommy' Sopwith, who tookhis flying brevet at Brooklands in November of 1910, and within fourdays made the British duration record of 108 miles in 3 hours 12minutes. On December 18th, 1910, he won the Baron de Forrest prize ofL4, 000 for the longest flight from England to the Continent, flyingfrom Eastchurch to Tirlemont, Belgium, in three hours, a distance of 161miles. After two years of touring in America, he returned to England andestablished a flying school. In 1912 he won the first aerial Derby, andin 1913 a machine of his design, a tractor biplane, raised the Britishheight record to 13, 000 feet (June 16th, at Brooklands). First asaviator, and then as designer, Sopwith has done much useful work inaviation. These are but a few, out of a host who contributed to the development offlying in this country, for, although France may be said to have setthe pace as regards development, Britain was not far behind. Frenchexperimenters received far more Government aid than did the earlyBritish aviators and designers--in the early days the two werepractically synonymous, and there are many stories of the very earlydays at Brooklands, where, when funds ran low, the ardent spiritspatched their trousers with aeroplane fabric and went on with their workwith Bohemian cheeriness. Cody, altering and experimenting on Laffan'sPlain, is the greatest figure of them all, but others rank, too, asgiants of the early days, before the war brought full recognition of theaeroplane's potentialities. One of the first men actually to fly in England, Mr J. C. T. Moore-Brabazon, was a famous figure in the days of exhibition flying, and won his reputation mainly through being first to fly a circularmile on a machine designed and built in Great Britain and piloted by aBritish subject. Moore-Brabazon's earliest flights were made in Franceon a Voisin biplane in 1908, and he brought this machine over toEngland, to the Aero Club grounds at Shellness, but soon decided that hewould pilot a British machine instead. An order was placed for a Shortmachine, and this, fitted with a 50-60 horse-power Green engine, wasused for the circular mile, which won a prize of L1, 000 offered by theDaily Mail, the feat being accomplished on October 30th, 1909. Fivedays later, Moore-Brabazon achieved the longest flight up to that timeaccomplished on a British-built machine, covering three and a halfmiles. In connection with early flying in England, it is claimed that A. V. Roe, flying 'Avro B, ', ' on June 8th, 1908, was actually the first manto leave the ground, this being at Brooklands, but in point of fact Codyantedated him. No record of early British fliers could be made without the name of C. S. Rolls, a son of Lord Llangattock, on June 2nd, 1910, he flew acrossthe English Channel to France, until he was duly observed over Frenchterritory, when he returned to England without alighting. The trip wasmade on a Wright biplane, and was the third Channel crossing by air, Bleriot having made the first, and Jacques de Lesseps the second. Rollswas first to make the return journey in one trip. He was eventuallykilled through the breaking of the tail-plane of his machine indescending at a flying meeting at Bournemouth. The machine was a Wrightbiplane, but the design of the tail-plane--which, by the way, wasan addition to the machine, and was not even sanctioned by theWrights--appears to have been carelessly executed, and the plane itselfwas faulty in construction. The breakage caused the machine to overturn, killing Rolls, who was piloting it. XIV. RHEIMS, AND AFTER The foregoing brief--and necessarily incomplete--survey of the earlyBritish group of fliers has taken us far beyond some of the great eventsof the early days of successful flight, and it is necessary to go backto certain landmarks in the history of aviation, first of which is thegreat meeting at Rheims in 1909. Wilbur Wright had come to Europe, and, flying at Le Mans and Pau--it was on August 8th, 1908, that WilburWright made the first of his ascents in Europe--had stimulated publicinterest in flying in France to a very great degree. Meanwhile, OrvilleWright, flying at Fort Meyer, U. S. A. , with Lieutenant Selfridge as apassenger, sustained an accident which very nearly cost him his lifethrough the transmission gear of the motor breaking. Selfridge waskilled and Orville Wright was severely injured--it was the first fatalaccident with a Wright machine. Orville Wright made a flight of over an hour on September 9th, 1908, andon December 31st of that year Wilbur flew for 2 hours 19 minutes. Thus, when the Rheims meeting was organised--more notable because it was thefirst of its kind, there were already records waiting to be broken. Thegreat week opened on August 22nd, there being thirty entrants, includingall the most famous men among the early fliers in France. Bleriot, fresh from his Channel conquest, was there, together with Henry Farman, Paulhan, Curtiss, Latham, and the Comte de Lambert, first pupil of theWright machine in Europe to achieve a reputation as an aviator. 'To say that this week marks an epoch in the history of the world is tostate a platitude. Nevertheless, it is worth stating, and for us whoare lucky enough to be at Rheims during this week there is a solidsatisfaction in the idea that we are present at the making of history. In perhaps only a few years to come the competitions of this week maylook pathetically small and the distances and speeds may appear paltry. Nevertheless, they are the first of their kind, and that is sufficient. ' So wrote a newspaper correspondent who was present at the famousmeeting, and his words may stand, being more than mere journalism; forthe great flying week which opened on August 22nd, 1909, ranks as one ofthe great landmarks in the history of heavier-than-air flight. The daybefore the opening of the meeting a downpour of rain spoilt the flyingground; Sunday opened with a fairly high wind, and in a lull M. Guffroy turned out on a crimson R. E. P. Monoplane, but the wheels ofhis undercarriage stuck in the mud and prevented him from rising inthe quarter of an hour allowed to competitors to get off the ground. Bleriot, following, succeeded in covering one side of the triangularcourse, but then came down through grit in the carburettor. Latham, following him with thirteen as the number of his machine, experiencedhis usual bad luck and came to earth through engine trouble after a veryshort flight. Captain Ferber, who, owing to military regulations, alwaysflew under the name of De Rue, came out next with his Voisin biplane, but failed to get off the ground; he was followed by Lefebvre on aWright biplane, who achieved the success of the morning by rounding thecourse--a distance of six and a quarter miles--in nine minutes with atwenty mile an hour wind blowing. His flight finished the morning. Wind and rain kept competitors out of the air until the evening, whenLatham went up, to be followed almost immediately by the Comte deLambert. Sommer, Cockburn (the only English competitor), Delagrange, Fournier, Lefebvre, Bleriot, Bunau-Varilla, Tissandier, Paulhan, and Ferber turned out after the first two, and the excitement of thespectators at seeing so many machines in the air at one time provokedwild cheering. The only accident of the day came when Bleriot damagedhis propeller in colliding with a haycock. The main results of the day were that the Comte de Lambert flew 30kilometres in 29 minutes 2 seconds; Lefebvre made the ten-kilometrecircle of the track in just a second under 9 minutes, while Tissandierdid it in 9 1/4 minutes, and Paulhan reached a height of 230 feet. Smallas these results seem to us now, and ridiculous as may seem enthusiasmat the sight of a few machines in the air at the same time, the RheimsMeeting remains a great event, since it proved definitely to the wholeworld that the conquest of the air had been achieved. Throughout the week record after record was made and broken. Thus onthe Monday, Lefebvre put up a record for rounding the course and Bleriotbeat it, to be beaten in turn by Glenn Curtiss on his Curtiss-Herringbiplane. On that day, too, Paulhan covered 34 3/4 miles in 1 hour 6minutes. On the next day, Paulhan on his Voisin biplane took the airwith Latham, and Fournier followed, only to smash up his machine bystriking an eddy of wind which turned him over several times. On theThursday, one of the chief events was Latham's 43 miles accomplished in1 hour 2 minutes in the morning and his 96. 5 miles in 2 hours 13 minutesin the afternoon, the latter flight only terminated by running out ofpetrol. On the Friday, the Colonel Renard French airship, which hadflown over the ground under the pilotage of M. Kapfarer, paid Rheims asecond visit; Latham manoeuvred round the airship on his Antoinette andfinally left it far behind. Henry Farman won the Grand Prix de Champagneon this day, covering 112 miles in 3 hours, 4 minutes, 56 seconds, Latham being second with his 96. 5 miles flight, and Paulhan third. On the Saturday, Glenn Curtiss came to his own, winning theGordon-Bennett Cup by covering 20 kilometres in 15 minutes 50. 6 seconds. Bleriot made a good second with 15 minutes 56. 2 seconds as his time, and Latham and Lefebvre were third and fourth. Farman carried off thepassenger prize by carrying two passengers a distance of 6 miles in 10minutes 39 seconds. On the last day Delagrange narrowly escaped seriousaccident through the bursting of his propeller while in the air, Curtissmade a new speed record by travelling at the rate of over 50 miles anhour, and Latham, rising to 500 feet, won the altitude prize. These are the cold statistics of the meeting; at this length of time itis difficult to convey any idea of the enthusiasm of the crowds overthe achievements of the various competitors, while the incidents ofthe week, comic and otherwise, are nearly forgotten now even by thosepresent in this making of history. Latham's great flight on the Thursdaywas rendered a breathless episode by a downpour of rain when he hadcovered all but a kilometre of the record distance previously achievedby Paulhan, and there was wild enthusiasm when Latham flew on throughthe rain until he had put up a new record and his petrol had run out. Again, on the Friday afternoon, the Colonel Renard took the air togetherwith a little French dirigible, Zodiac III; Latham was already in theair directly over Farman, who was also flying, and three crows whichturned out as rivals to the human aviators received as much cheering fortheir appearance as had been accorded to the machines, which doubtlessthey could not understand. Frightened by the cheering, the crows triedto escape from the course, but as they came near the stands, the crowdrose to cheer again and the crows wheeled away to make a second chargetowards safety, with the same result; the crowd rose and cheered at thema third and fourth time; between ten and fifteen thousand people stoodon chairs and tables and waved hats and handkerchiefs at three ordinary, everyday crows. One thoughtful spectator, having thoroughly enjoyed thefunny side of the incident, remarked that the ultimate mastery of theair lies with the machine that comes nearest to natural flight. Thisstill remains for the future to settle. Farman's world record, which won the Grand Prix de Champagne, was donewith a Gnome Rotary Motor which had only been run on the test benchand was fitted to his machine four hours before he started on the greatflight. His propeller had never been tested, having only been completedthe night before. The closing laps of that flight, extending as they didinto the growing of the dusk, made a breathlessly eerie experience forsuch of the spectators as stayed on to watch--and these were many. Nightcame on steadily and Farman covered lap after lap just as steadily, abuzzing, circling mechanism with something relentless in its isolatedpersistency. The final day of the meeting provided a further record in the quartermillion spectators who turned up to witness the close of the great week. Bleriot, turning out in the morning, made a landing in some such fashionas flooded the carburettor and caused it to catch fire. Bleriot himselfwas badly burned, since the petrol tank burst and, in the end, onlythe metal parts of the machine were left. Glenn Curtis tried to beatBleriot's time for a lap of the course, but failed. In the evening, Farman and Latham went out and up in great circles, Farman cleaving hisway upward in what at the time counted for a huge machine, on circlesof about a mile diameter. His first round took him level with the top ofthe stands, and, in his second, he circled the captive balloon anchoredin the middle of the grounds. After another circle, he came down on along glide, when Latham's lean Antoinette monoplane went up in circlesmore graceful than those of Farman. 'Swiftly it rose and swept roundclose to the balloon, veered round to the hangars, and out over to theRheims road. Back it came high over the stands, the people craning theirnecks as the shrill cry of the engine drew nearer and nearer behind thestands. Then of a sudden, the little form appeared away up in the deeptwilight blue vault of the sky, heading straight as an arrow for theanchored balloon. Over it, and high, high above it went the Antoinette, seemingly higher by many feet than the Farman machine. Then, wheelingin a long sweep to the left, Latham steered his machine round past thestands, where the people, their nerve-tension released on seeing themachine descending from its perilous height of 500 feet, shouted theirfrenzied acclamations to the hero of the meeting. 'For certainly "Le Tham, " as the French call him, was the popular hero. He always flew high, he always flew well, and his machine was a joy tothe eye, either afar off or at close quarters. The public feeling forBleriot is different. Bleriot, in the popular estimation, is the man whofights against odds, who meets the adverse fates calmly and with goodcourage, and to whom good luck comes once in a while as a reward formuch labour and anguish, bodily and mental. Latham is the darling ofthe Gods, to whom Fate has only been unkind in the matter of the Channelflight, and only then because the honour belonged to Bleriot. 'Next to these two, the public loved most Lefebvre, the joyous, thegymnastic. Lefebvre was the comedian of the meeting. When things beganto flag, the gay little Lefebvre would trot out to his starting rail, out at the back of the judge's enclosure opposite the stands, and aftera little twisting of propellers his Wright machine would bounce off theend of its starting rail and proceed to do the most marvellous tricksfor the benefit of the crowd, wheeling to right and left, darting up anddown, now flying over a troop of the cavalry who kept the plain clear ofpeople and sending their horses into hysterics, anon making straightfor an unfortunate photographer who would throw himself and his preciouscamera flat on the ground to escape annihilation as Lefebvre swept overhim 6 or 7 feet off the ground. Lefebvre was great fun, and when he hadonce found that his machine was not fast enough to compete for speedwith the Bleriots, Antoinettes, and Curtiss, he kept to his metier ofamusing people. The promoters of the meeting owe Lefebvre a debt ofgratitude, for he provided just the necessary comic relief. '--(The Aero, September 7th, 1909. ) It may be noted, in connection with the fact that Cockburn was the onlyEnglish competitor at the meeting, that the Rheims Meeting did more thananything which had preceded it to waken British interest in aviation. Previously, heavier-than-air flight in England had been regarded asa freak business by the great majority, and the very few pioneers whopersevered toward winning England a share in the conquest of the aircame in for as much derision as acclamation. Rheims altered this; ittaught the world in general, and England in particular, that a seriousrival to the dirigible balloon had come to being, and it awakened thethinking portion of the British public to the fact that the aeroplanehad a future. The success of this great meeting brought about a host of imitationsof which only a few deserve bare mention since, unlike the first, theytaught nothing and achieved little. There was the meeting at Boulognelate in September of 1909, of which the only noteworthy event wasFerber's death. There was a meeting at Brescia where Curtiss again tookfirst prize for speed and Rougier put up a world's height record of 645feet. The Blackpool meeting followed between 18th and 23rd of October, 1909, forming, with the exception of Doncaster, the first British FlyingMeeting. Chief among the competitors were Henry Farman, who took thedistance prize, Rougier, Paulhan, and Latham, who, by a flight in a highwind, convinced the British public that the theory that flying was onlypossible in a calm was a fallacy. A meeting at Doncaster was practicallysimultaneous with the Blackpool week; Delagrange, Le Blon, Sommer, andCody were the principal figures in this event. It should be addedthat 130 miles was recorded as the total flown at Doncaster, while atBlackpool only 115 miles were flown. Then there were Juvisy, the firstParisian meeting, Wolverhampton, and the Comte de Lambert's flight roundthe Eiffel Tower at a height estimated at between 1, 200 and 1, 300 feet. This may be included in the record of these aerial theatricals, since itwas nothing more. Probably wakened to realisation of the possibilities of the aeroplane bythe Rheims Meeting, Germany turned out its first plane late in 1909. It was known as the Grade monoplane, and was a blend of the Bleriot andSantos-Dumont machines, with a tail suggestive of the Antoinette type. The main frame took the form of a single steel tube, at the forward endof which was rigged a triangular arrangement carrying the pilot's seatand the landing wheels underneath, with the wing warping wires and staysabove. The sweep of the wings was rather similar to the later Taubedesign, though the sweep back was not so pronounced, and the machine wasdriven by a four-cylinder, 20 horse-power, air-cooled engine which drovea two-bladed tractor propeller. In spite of Lilienthal's pioneerwork years before, this was the first power-driven German plane whichactually flew. Eleven months after the Rheims meeting came what may be reckoned theonly really notable aviation meeting on English soil, in the form of theBournemouth week, July 10th to 16th, 1910. This gathering is noteworthymainly in view of the amazing advance which it registered on the Rheimsperformances. Thus, in the matter of altitude, Morane reached 4, 107feet and Drexel came second with 2, 490 feet. Audemars on a Demoisellemonoplane made a flight of 17 miles 1, 480 yards in 27 minutes 17. 2seconds, a great flight for the little Demoiselle. Morane achieved aspeed of 56. 64 miles per hour, and Grahame White climbed to 1, 000 feetaltitude in 6 minutes 36. 8 seconds. Machines carrying the Gnome engineas power unit took the great bulk of the prizes, and British-builtengines were far behind. The Bournemouth Meeting will always be remembered with regret for thetragedy of C. S. Rolls's death, which took place on the Tuesday, thesecond day of the meeting. The first competition of the day was thatfor the landing prize; Grahame White, Audemars, and Captain Dickson hadlanded with varying luck, and Rolls, following on a Wright machine witha tail-plane which ought never to have been fitted and was not part ofthe Wright design, came down wind after a left-hand turn and turned leftagain over the top of the stands in order to land up wind. He began todive when just clear of the stands, and had dropped to a height of 40feet when he came over the heads of the people against the barriers. Finding his descent too steep, he pulled back his elevator lever tobring the nose of the machine up, tipping down the front end of the tailto present an almost flat surface to the wind. Had all gone well, thenose of the machine would have been forced up, but the strain on thetail and its four light supports was too great; the tail collapsed, thewind pressed down the biplane elevator, and the machine dived verticallyfor the remaining 20 feet of the descent, hitting the ground verticallyand crumpling up. Major Kennedy, first to reach the debris, found Rollslying with his head doubled under him on the overturned upper mainplane; the lower plane had been flung some few feet away with the engineand tanks under it. Rolls was instantaneously killed by concussion ofthe brain. Antithesis to the tragedy was Audemars on his Demoiselle, which wasnamed 'The Infuriated Grasshopper. ' Concerning this, it was recordedat the time that 'Nothing so excruciatingly funny as the action ofthis machine has ever been seen at any aviation ground. The littletwo-cylinder engine pops away with a sound like the frantic drawing ofginger beer corks; the machine scutters along the ground with its tailwell up; then down comes the tail suddenly and seems to slap the groundwhile the front jumps up, and all the spectators rock with laughter. Thewhole attitude and the jerky action of the machine suggest a grasshopperin a furious rage, and the impression is intensified when it comes down, as it did twice on Wednesday, in long grass, burying its head in theground in its temper. '--(The Aero, July, 1910. ) The Lanark Meeting followed in August of the same year, and with thebare mention of this, the subject of flying meetings may he leftalone, since they became mere matters of show until there came militarycompetitions such as the Berlin Meeting at the end of August, 1910, and the British War office Trials on Salisbury Plain, when Cody won hisgreatest triumphs. The Berlin meeting proved that, from the time of theconstruction of the first successful German machine mentioned above, tothe date of the meeting, a good number of German aviators had qualifiedfor flight, but principally on Wright and Antoinette machines, thoughby that time the Aviatik and Dorner German makes had taken the air. TheBritish War office Trials deserve separate and longer mention. In 1910 in spite of official discouragement, Captain Dickson proved thevalue of the aeroplane for scouting purposes by observing movementsof troops during the Military Manoeuvres on Salisbury Plain. Lieut. Lancelot Gibbs and Robert Loraine, the actor-aviator, also made flightsover the manoeuvre area, locating troops and in a way anticipating theformation and work of the Royal Flying Corps by a usefulness which couldnot be officially recognised. XV. THE CHANNEL CROSSING It may be said that Louis Bleriot was responsible for the second greatlandmark in the history of successful flight. The day when the brothersWright succeeded in accomplishing power-driven flight ranks as the firstof these landmarks. Ader may or may not have left the ground, but thewreckage of his 'Avion' at the end of his experiment places his doubtfulsuccess in a different category from that of the brothers Wright andleaves them the first definite conquerors, just as Bleriot ranks asfirst definite conqueror of the English Channel by air. In a way, Louis Bleriot ranks before Farman in point of time; hisfirst flapping-wing model was built as early as 1900, and Voisin flew abiplane glider of his on the Seine in the very early experimental days. Bleriot's first four machines were biplanes, and his fifth, a monoplane, was wrecked almost immediately after its construction. Bleriot hadstudied Langley's work to a certain extent, and his sixth constructionwas a double monoplane based on the Langley principle. A month afterhe had wrecked this without damaging himself--for Bleriot had as manymiraculous escapes as any of the other fliers-he brought out numberseven, a fairly average monoplane. It was in December of 1907 after aseries of flights that he wrecked this machine, and on its successor, inJuly of 1908, he made a flight of over 8 minutes. Sundry flights, moreor less successful, including the first cross-country flight from Touryto Artenay, kept him busy up to the beginning of November, 1908, whenthe wreckage in a fog of the machine he was flying sent him to thebuilding of 'number eleven, ' the famous cross-channel aeroplane. Number eleven was shown at the French Aero Show in the Grand Palaisand was given its first trials on the 18th January, 1909. It was firstfitted with a R. E. P. Motor and had a lifting area of 120 square feet, which was later increased to 150 square feet. The framework was of oakand poplar spliced and reinforced with piano wire; the weight of themachine was 47 lbs. And the undercarriage weight a further 60 lbs. , thisconsisting of rubber cord shock absorbers mounted on two wheels. TheR. E. P. Motor was found unsatisfactory, and a three-cylinder Anzaniof 105 mm. Bore and 120 mm. Stroke replaced it. An accident seriouslydamaged the machine on June 2nd, but Bleriot repaired it and tested itat Issy, where between June 19th and June 23rd he accomplished flightsof 8, 12, 15, 16, and 36 minutes. On July 4th he made a 50-minute flightand on the 13th flew from Etampes to Chevilly. A few further details of construction may be given: the wings themselvesand an elevator at the tail controlled the rate of ascent and descent, while a rudder was also fitted at the tail. The steering lever, working on a universally jointed shaft--forerunner of the modernjoystick--controlled both the rudder and the wings, while a pedalactuated the elevator. The engine drove a two-bladed tractor screw of 6feet 7 inches diameter, and the angle of incidence of the wings was 20degrees. Timed at Issy, the speed of the machine was given as 36 milesan hour, and as Bleriot accomplished the Channel flight of 20 miles in37 minutes, he probably had a slight following wind. The Daily Mail had offered a prize of L1, 000 for the first Cross-Channelflight, and Hubert Latham set his mind on winning it. He put up ashelter on the French coast at Sangatte, half-way between Calais andCape Blanc Nez. From here he made his first attempt to fly to Englandon Monday the 19th of July. He soared to a fair height, circling, andreached an estimated height of about 900 feet as he came over the waterwith every appearance of capturing the Cross-Channel prize. The luckwhich dogged his career throughout was against him, for, after he hadcovered some 8 miles, his engine stopped and he came down to the waterin a series of long glides. It was discovered afterward that a smallpiece of wire had worked its way into a vital part of the engine to robLatham of the honour he coveted. The tug that came to his rescue foundhim seated on the fuselage of his Antoinette, smoking a cigarette andwaiting for a boat to take him to the tug. It may be remarked thatLatham merely assumed his Antoinette would float in case he failed tomake the English coast; he had no actual proof. Bleriot immediately entered his machine for the prize and took up hisquarters at Barraques. On Sunday, July 25th, 1909, shortly after 4 a. M. , Bleriot had his machine taken out from its shelter and prepared forflight. He had been recently injured in a petrol explosion and hobbledout on crutches to make his cross-Channel attempt; he made two greatcircles in the air to try the machine, and then alighted. 'In tenminutes I start for England, ' he declared, and at 4. 35 the motor wasstarted up. After a run of 100 yards, the machine rose in the air andgot a height of about 100 feet over the land, then wheeling sharplyseaward and heading for Dover. Bleriot had no means of telling direction, and any change of wind mighthave driven him out over the North Sea, to be lost, as were Cecil Graceand Hamel later on. Luck was with him, however, and at 5. 12 a. M. Of thatJuly Sunday, he made his landing in the North Fall meadow, just behindDover Castle. Twenty minutes out from the French coast, he lost sight ofthe destroyer which was patrolling the Channel, and at the same timehe was out of sight of land without compass or any other means ofascertaining his direction. Sighting the English coast, he found thathe had gone too far to the east, for the wind increased in strengththroughout the flight, this to such an extent as almost to turn themachine round when he came over English soil. Profiting by Latham'sexperience, Bleriot had fitted an inflated rubber cylinder a foot indiameter by 5 feet in length along the middle of his fuselage, to renderfloating a certainty in case he had to alight on the water. Latham in his camp at Sangatte had been allowed to sleep through thecalm of the early morning through a mistake on the part of a friend, andwhen his machine was turned out--in order that he might emulate Bleriot, although he no longer hoped to make the first flight, it took so longto get the machine ready and dragged up to its starting-point that therewas a 25 mile an hour wind by the time everything was in readiness. Latham was anxious to make the start in spite of the wind, but theDirectors of the Antoinette Company refused permission. It was not untiltwo days later that the weather again became favourable, and then with afresh machine, since the one on which he made his first attempt hadbeen very badly damaged in being towed ashore, he made a circular trialflight of about 5 miles. In landing from this, a side gust of wind drovethe nose of the machine against a small hillock, damaging both propellerblades and chassis, and it was not until evening that the damage wasrepaired. French torpedo boats were set to mark the route, and Latham set out onhis second attempt at six o'clock. Flying at a height of 200 feet, heheaded over the torpedo boats for Dover and seemed certain of making theEnglish coast, but a mile and a half out from Dover his engine failedhim again, and he dropped to the water to be picked up by the steampinnace of an English warship and put aboard the French destroyerEscopette. There is little to choose between the two aviators for courage inattempting what would have been considered a foolhardy feat a year ortwo before. Bleriot's state, with an abscess in the burnt foot which hadto control the elevator of his machine, renders his success all themore remarkable. His machine was exhibited in London for a time, andwas afterwards placed in the Conservatoire des Arts et Metiers, while amemorial in stone, copying his monoplane in form, was let into the turfat the point where he landed. The second Channel crossing was not made until 1910, a year of newrecords. The altitude record had been lifted to over 10, 000 feet, theduration record to 8 hours 12 minutes, and the distance for a singleflight to 365 miles, while a speed of over 65 miles an hour had beenachieved, when Jacques de Lesseps, son of the famous engineer of SuezCanal and Panama fame, crossed from France to England on a Bleriotmonoplane. By this time flying had dropped so far from the marvellousthat this second conquest of the Channel aroused but slight publicinterest in comparison with Bleriot's feat. The total weight of Bleriot's machine in Cross Channel trim was 660lbs. , including the pilot and sufficient petrol for a three hours' run;at a speed of 37 miles an hour, it was capable of carrying about 5lbs. Per square foot of lifting surface. It was the three-cylinder 25horse-power Anzani motor which drove the machine for the flight. Shortlyafter the flight had been accomplished, it was announced that theBleriot firm would construct similar machines for sale at L400 apiece--agood commentary on the prices of those days. On June the 2nd, 1910, the third Channel crossing was made by C. S. Rolls, who flew from Dover, got himself officially observed over Frenchsoil at Barraques, and then flew back without landing. He was the firstto cross from the British side of the Channel and also was the firstaviator who made the double journey. By that time, however, distanceflights had so far increased as to reduce the value of the feat, andthenceforth the Channel crossing was no exceptional matter. The honour, second only to that of the Wright Brothers, remains with Bleriot. XVI. LONDON TO MANCHESTER The last of the great contests to arouse public enthusiasm was theLondon to Manchester Flight of 1910. As far back as 1906, the DailyMail had offered a prize of L10, 000 to the first aviator who shouldaccomplish this journey, and, for a long time, the offer was regarded asa perfectly safe one for any person or paper to make--it brought forthfar more ridicule than belief. Punch offered a similar sum to the firstman who should swim the Atlantic and also for the first flight to Marsand back within a week, but in the spring of 1910 Claude Grahame Whiteand Paulhan, the famous French pilot, entered for the 183 mile run onwhich the prize depended. Both these competitors flew the Farman biplanewith the 50 horse-power Gnome motor as propulsive power. Grahame Whitesurveyed the ground along the route, and the L. & N. W. Railway Company, at his request, whitewashed the sleepers for 100 yards on the north sideof all junctions to give him his direction on the course. The machinewas run out on to the starting ground at Park Royal and set going at5. 19 a. M. On April 23rd. After a run of 100 yards, the machine went upover Wormwood Scrubs on its journey to Normandy, near Hillmorten, whichwas the first arranged stopping place en route; Grahame White landedhere in good trim at 7. 20 a. M. , having covered 75 miles and made aworld's record cross country flight. At 8. 15 he set off again to comedown at Whittington, four miles short of Lichfield, at about 9. 20, withhis machine in good order except for a cracked landing skid. Twice, onthis second stage of the journey, he had been caught by gusts of windwhich turned the machine fully round toward London, and, when over awood near Tamworth, the engine stopped through a defect in the balancesprings of two exhaust valves; although it started up again after a 100foot glide, it did not give enough power to give him safety in the galehe was facing. The rising wind kept him on the ground throughout theday, and, though he hoped for better weather, the gale kept up untilthe Sunday evening. The men in charge of the machine during its halt hadattempted to hold the machine down instead of anchoring it with stakesand ropes, and, in consequence of this, the wind blew the machine overon its back, breaking the upper planes and the tail. Grahame White hadto return to London, while the damaged machine was prepared for a secondflight. The conditions of the competition enacted that the full journeyshould be completed within 24 hours, which made return to the startingground inevitable. Louis Paulhan, who had just arrived with his Farman machine, immediatelygot it unpacked and put together in order to be ready to make hisattempt for the prize as soon as the weather conditions should admit. At 5. 31 p. M. , on April 27th, he went up from Hendon and had travelled50 miles when Grahame White, informed of his rival's start, set out toovertake him. Before nightfall Paulhan landed at Lichfield, 117 milesfrom London, while Grahame White had to come down at Roden, only 60miles out. The English aviator's chance was not so small as it seemed, for, as Latham had found in his cross-Channel attempts, engine failurewas more the rule than the exception, and a very little thing mightreverse the relative positions. A special train accompanied Paulhan along the North-Western route, conveying Madame Paulhan, Henry Farman, and the mechanics who fitted theFarman biplane together. Paulhan himself, who had flown at a height of1, 000 feet, spent the night at Lichfield, starting again at 4. 9 a. M. On the 28th, passing Stafford at 4. 45, Crewe at 5. 20, and landing atBurnage, near Didsbury, at 5. 32, having had a clean run. Meanwhile, Grahame White had made a most heroic attempt to beat hisrival. An hour before dawn on the 28th, he went to the small field inwhich his machine had landed, and in the darkness managed to make anascent from ground which made starting difficult even in daylight. Purely by instinct and his recollection of the aspect of things thenight before, he had to clear telegraph wires and a railway bridge, neither of which he could possibly see at that hour. His engine, too, was faltering, and it was obvious to those who witnessed his start thatits note was far from perfect. At 3. 50 he was over Nuneaton and making good progress; betweenAtherstone and Lichfield the wind caught him and the engine failed moreand more, until at 4. 13 in the morning he was forced to come to earth, having covered 6 miles less distance than in his first attempt. It waspurely a case of engine failure, for, with full power, he would havepassed over Paulhan just as the latter was preparing for the restart. Taking into consideration the two machines, there is little doubt thatGrahame White showed the greater flying skill, although he lost theprize. After landing and hearing of Paulhan's victory, on which he wiredcongratulations, he made up his mind to fly to Manchester within the24 hours. He started at 5 o'clock in the afternoon from Polesworth, hislanding place, but was forced to land at 5. 30 at Whittington, wherehe had landed on the previous Saturday. The wind, which had forced hisdescent, fell again and permitted of starting once more; on this thirdstage he reached Lichfield, only to make his final landing at 7. 15 p. M. , near the Trent Valley station. The defective running of the Gnome engineprevented his completing the course, and his Farman machine had to bebrought back to London by rail. The presentation of the prize to Paulhan was made the occasion for theannouncement of a further competition, consisting of a 1, 000 mile flightround a part of Great Britain. In this, nineteen competitors started, and only four finished; the end of the race was a great fight betweenBeaumont and Vedrines, both of whom scorned weather conditions in theirdetermination to win. Beaumont made the distance in a flying time of22 hours 28 minutes 19 seconds, and Vedrines covered the journey ina little over 23 1/2 hours. Valentine came third on a Deperdussinmonoplane and S. F. Cody on his Cathedral biplane was fourth. This wasin 1911, and by that time heavier-than-air flight had so far advancedthat some pilots had had war experience in the Italian campaign inTripoli, while long cross-country flights were an everyday event, andbad weather no longer counted. XVII. A SUMMARY, TO 1911 There is so much overlapping in the crowded story of the first yearsof successful power-driven flight that at this point it is advisable tomake a concise chronological survey of the chief events of the period ofearly development, although much of this is of necessity recapitulation. The story begins, of course, with Orville Wright's first flight of 852feet at Kitty Hawk on December 19th, 1903. The next event of note wasWright's flight of 11. 12 miles in 18 minutes 9 seconds at Dayton, Ohio, on September 26th, 1905, this being the first officially recordedflight. On October 4th of the same year, Wright flew 20. 75 miles in 33minutes 17 seconds, this being the first flight of over 20 miles evermade. Then on September 14th 1906, Alberto Santos-Dumont made aflight of eight seconds on the second heavier-than-air machine he hadconstructed. It was a big box-kite-like machine; this was the secondpower-driven aeroplane in Europe to fly, for although Santos-Dumont'sfirst machine produced in 1905 was reckoned an unsuccessful design, ithad actually got off the ground for brief periods. Louis Bleriot cameinto the ring on April 5th, 1907, with a first flight of 6 seconds on aBleriot monoplane, his eighth but first successful construction. Henry Farman made his first appearance in the history of aviation with aflight of 935 feet on a Voisin biplane on October 15th 1907. On October25th, in a flight of 2, 530 feet, he made the first recorded turn inthe air, and on March 29th, 1908, carrying Leon Delagrange on a Voisinbiplane, he made the first passenger flight. On April 10th of thisyear, Delagrange, in flying 1 1/2 miles, made the first flight in Europeexceeding a mile in distance. He improved on this by flying 10 1/2 milesat Milan on June 22nd, while on July 8th, at Turin, he took up MadamePeltier, the first woman to make an aeroplane flight. Wilbur Wright, coming over to Europe, made his first appearance on theContinent with a flight of 1 3/4 minutes at Hunaudieres, France, onAugust 8th, 1908. On September 6th, at Chalons, he flew for 1 hour 4minutes 26 seconds with a passenger, this being the first flight inwhich an hour in the air was exceeded with a passenger on board. On September 12th 1908, Orville Wright, flying at Fort Meyer, U. S. A. , with Lieut. Selfridge as passenger, crashed his machine, sufferingsevere injuries, while Selfridge was killed. This was the firstaeroplane fatality. On October 30th, 1908, Farman made the firstcross-country flight, covering the distance of 17 miles between Bouy andRheims. The next day, Louis Bleriot, in flying from Toury to Artenay, made two landings en route, this being the first cross-country flightwith landings. On the last day of the year, Wilbur Wright won theMichelin Cup at Auvours with a flight of 90 miles, which, lasting 2hours 20 minutes 23 seconds, exceeded 2 hours in the air for the firsttime. On January 2nd, 1909, S. F. Cody opened the New Year by making the firstobserved flight at Farnborough on a British Army aeroplane. It was notuntil July 18th of 1909 that the first European height record deservingof mention was put up by Paulhan, who achieved a height of 450 feet on aVoisin biplane. This preceded Latham's first attempt to fly the Channelby two days, and five days later, on the 25th of the month, Bleriot madethe first Channel crossing. The Rheims Meeting followed on August 22nd, and it was a great day for aviation when nine machines were seen inthe air at once. It was here that Farman, with a 118 mile flight, first exceeded the hundred miles, and Latham raised the height recordofficially to 500 feet, though actually he claimed to have reached 1, 200feet. On September 8th, Cody, flying from Aldershot, made a 40 milejourney, setting up a new cross-country record. On October 19th theComte de Lambert flew from Juvisy to Paris, rounded the Eiffel Tower andflew back. J. T. C. Moore-Brabazon made the first circular mile flightby a British aviator on an all-British machine in Great Britain, onOctober 30th, flying a Short biplane with a Green engine. Paulhan, flying at Brooklands on November 2nd, accomplished 96 miles in 2 hours48 minutes, creating a British distance record; on the followingday, Henry Farman made a flight of 150 miles in 4 hours 22 minutesat Mourmelon, and on the 5th of the month, Paulhan, flying a Farmanbiplane, made a world's height record of 977 feet. This, however, wasnot to stand long, for Latham got up to 1, 560 feet on an Antoinette atMourmelon on December 1st. December 31st witnessed the first flightin Ireland, made by H. Ferguson on a monoplane which he himself hadconstructed at Downshire Park, Lisburn. These, thus briefly summarised, are the principal events up to the endof 1909. 1910 opened with tragedy, for on January 4th Leon Delagrange, one of the greatest pilots of his time, was killed while flying atPau. The machine was the Bleriot XI which Delagrange had used at theDoncaster meeting, and to which Delagrange had fitted a 50 horse-powerGnome engine, increasing the speed of the machine from its original30 to 45 miles per hour. With the Rotary Gnome engine there was ofnecessity a certain gyroscopic effect, the strain of which proved toomuch for the machine. Delagrange had come to assist in the inaugurationof the Croix d'Hins aerodrome, and had twice lapped the course at aheight of about 60 feet. At the beginning of the third lap, the strainof the Gnome engine became too great for the machine; one wing collapsedas if the stay wires had broken, and the whole machine turned over andfell, killing Delagrange. On January 7th Latham, flying at Mourmelon, first made the verticalkilometre and dedicated the record to Delagrange, this being the day ofhis friend's funeral. The record was thoroughly authenticated by a largeregistering barometer which Latham carried, certified by the officialsof the French Aero Club. Three days later Paulhan, who was at LosAngeles, California, raised the height record to 4, 146 feet. On January 25th the Brussels Exhibition opened, when the Antoinettemonoplane, the Gaffaux and Hanriot monoplanes, together with thed'Hespel aeroplane, were shown; there were also the dirigible Belgicaand a number of interesting aero engines, including a German airshipengine and a four-cylinder 50 horse-power Miesse, this last air-cooledby means of 22 fans driving a current of air through air jacketssurrounding fluted cylinders. On April 2nd Hubert Le Blon, flying a Bleriot with an Anzani engine, was killed while flying over the water. His machine was flying quitesteadily, when it suddenly heeled over and came down sideways into thesea; the motor continued running for some seconds and the whole machinewas drawn under water. When boats reached the spot, Le Blon was foundlying back in the driving seat floating just below the surface. He haddone good flying at Doncaster, and at Heliopolis had broken the world'sspeed records for 5 and 10 kilometres. The accident was attributed tofracture of one of the wing stay wires when running into a gust of wind. The next notable event was Paulhan's London-Manchester flight, of whichfull details have already been given. In May Captain Bertram Dickson, flying at the Tours meeting, beat all the Continental fliers whom heencountered, including Chavez, the Peruvian, who later made thefirst crossing of the Alps. Dickson was the first British winner ofinternational aviation prizes. C. S. Rolls, of whom full details have already been given, was killed atBournemouth on July 12th, being the first British aviator of note to bekilled in an aeroplane accident. His return trip across the Channel hadtaken place on June 2nd. Chavez, who was rapidly leaping into fame, asa pilot, raised the British height record to 5, 750 feet while flying atBlackpool on August 3rd. On the 11th of that month, Armstrong Drexel, flying a Bleriot, made a world's height record of 6, 745 feet. It was in 1910 that the British War office first began fully to realisethat there might be military possibilities in heavier-than-air flying. C. S. Rolls had placed a Wright biplane at the disposal of the militaryauthorities, and Cody, as already recorded, had been experimenting witha biplane type of his own for some long period. Such development as wasachieved was mainly due to the enterprise and energy of Colonel J. E. Capper, C. B. , appointed to the superintendency of the Balloon Factoryand Balloon School at Farnborough in 1906. Colonel Capper's retirementin 1910 brought (then) Mr Mervyn O'Gorman to command, and by that timethe series of successes of the Cody biplane, together with the provedefficiency of the aeroplane in various civilian meetings, had convincedthe British military authorities that the mastery of the air did not liealtogether with dirigible airships, and it may be said that in 1910 theBritish War office first began seriously to consider the possibilitiesof the aeroplane, though two years more were to elapse before theformation of the Royal Flying Corps marked full realisation of itsvalue. A triumph and a tragedy were combined in September of 1910. On the 23rdof the month, Georges Chavez set out to fly across the Alps on a Bleriotmonoplane. Prizes had been offered by the Milan Aviation Committee fora flight from Brigue in Switzerland over the Simplon Pass to Milan, a distance of 94 miles with a minimum height of 6, 600 feet above sealevel. Chavez started at 1. 30 p. M. On the 23rd, and 41 minutes later hereached Domodossola, 25 miles distant. Here he descended, numbed withthe cold of the journey; it was said that the wings of his machinecollapsed when about 30 feet from the ground, but however this mayhave been, he smashed the machine on landing, and broke both legs, inaddition to sustaining other serious injuries. He lay in hospital untilthe 27th September, when he died, having given his life to the conquestof the Alps. His death in the moment of success was as great a tragedyas were those of Pilcher and Lilienthal. The day after Chavez's death, Maurice Tabuteau flew across the Pyrenees, landing in the square at Biarritz. On December 30th, Tabuteau made aflight of 365 miles in 7 hours 48 minutes. Farman, on December 18th, hadflown for over 8 hours, but his total distance was only 282 miles. Theautumn of this year was also noteworthy for the fact that aeroplaneswere first successfully used in the French Military Manoeuvres. TheBritish War Office, by the end of the year, had bought two machines, amilitary type Farman and a Paulhan, ignoring British experimenters andaeroplane builders of proved reliability. These machines, added to anold Bleriot two-seater, appear to have constituted the British aeroplanefleet of the period. There were by this time three main centres of aviation in England, apartfrom Cody, alone on Laffan's Plain. These three were Brooklands, Hendon, and the Isle of Sheppey, and of the three Brooklands was chief. Here such men as Graham Gilmour, Rippen, Leake, Wickham, and Thomaspersistently experimented. Hendon had its own little group, andShellbeach, Isle of Sheppey, held such giants of those days as C. S. Rolls and Moore Brabazon, together with Cecil Grace and Rawlinson. Oneor other, and sometimes all of these were deserted on the occasion ofsome meeting or other, but they were the points where the spade work wasdone, Brooklands taking chief place. 'If you want the early historyof flying in England, it is there, ' one of the early school remarked, pointing over toward Brooklands course. 1911 inaugurated a new series of records of varying character. Onthe 17th January, E. B. Ely, an American, flew from the shore of SanFrancisco to the U. S. Cruiser Pennsylvania, landing on the cruiser, and then flew back to the shore. The British military designing ofaeroplanes had been taken up at Farnborough by G. H. De Havilland, whoby the end of January was flying a machine of his own design, when henarrowly escaped becoming a casualty through collision with an obstacleon the ground, which swept the undercarriage from his machine. A list of certified pilots of the countries of the world was issuedearly in 1911, showing certificates granted up to the end of 1910. France led the way easily with 353 pilots; England came next with 57, and Germany next with 46; Italy owned 32, Belgium 27, America 26, andAustria 19; Holland and Switzerland had 6 aviators apiece, while Denmarkfollowed with 3, Spain with 2, and Sweden with 1. The first certificatein England was that of J. T. C. Moore-Brabazon, while Louis Bleriot wasfirst on the French list and Glenn Curtiss, first holder of an Americancertificate, also held the second French brevet. On the 7th March, Eugene Renaux won the Michelin Grand Prize by flyingfrom the French Aero Club ground at St Cloud and landing on the Puy deDome. The landing, which was one of the conditions of the prize, wasone of the most dangerous conditions ever attached to a competition;it involved dropping on to a little plateau 150 yards square, witha possibility of either smashing the machine against the face of themountain, or diving over the edge of the plateau into the gulf beneath. The length of the journey was slightly over 200 miles and the height ofthe landing point 1, 465 metres, or roughly 4, 500 feet above sea-level. Renaux carried a passenger, Doctor Senoucque, a member of Charcot'sSouth Polar Expedition. The 1911 Aero Exhibition held at Olympia bore witness to the enormousstrides made in construction, more especially by British designers, between 1908 and the opening of the Show. The Bristol Firm showed threemachines, including a military biplane, and the first British builtbiplane with tractor screw. The Cody biplane, with its enormous sizerendering it a prominent feature of the show, was exhibited. Itsdesigner anticipated later engines by expressing his desire for a motorof 150 horse-power, which in his opinion was necessary to get the bestresults from the machine. The then famous Dunne monoplane was exhibitedat this show, its planes being V-shaped in plan, with apex leading. Itembodied the results of very lengthy experiments carried out both withgliders and power-driven machines by Colonel Capper, Lieut. Gibbs, and Lieut. Dunne, and constituted the longest step so far taken in thedirection of inherent stability. Such forerunners of the notable planes of the war period as the MartinHandasyde, the Nieuport, Sopwith, Bristol, and Farman machines, werefeatures of the show; the Handley-Page monoplane, with a span of 32feet over all, a length of 22 feet, and a weight of 422 lbs. , bore norelation at all to the twin-engined giant which later made this firmfamous. In the matter of engines, the principal survivals to the presentday, of which this show held specimens, were the Gnome, Green, Renaultair-cooled, Mercedes four-cylinder dirigible engine of 115 horse-power, and 120 horsepower Wolseley of eight cylinders for use with dirigibles. On April 12th, of 1911, Paprier, instructor at the Bleriot school atHendon, made the first non-stop flight between London and Paris. He leftthe aerodrome at 1. 37 p. M. , and arrived at Issy-les-Moulineaux at 5. 33p. M. , thus travelling 250 miles in a little under 4 hours. He followedthe railway route practically throughout, crossing from Dover to nearlyopposite Calais, keeping along the coast to Boulogne, and then followingthe Nord Railway to Amiens, Beauvais, and finally Paris. In May, the Paris-Madrid race took place; Vedrines, flying a Moranebiplane, carried off the prize by first completing the distance of 732miles. The Paris-Rome race of 916 miles was won in the same month byBeaumont, flying a Bleriot monoplane. In July, Koenig won the GermanNational Circuit race of 1, 168 miles on an Albatross biplane. This waspractically simultaneous with the Circuit of Britain won by Beaumont, who covered 1, 010 miles on a Bleriot monoplane, having already wonthe Paris-Brussels-London-Paris Circuit of 1, 080 miles, this also ona Bleriot. It was in August that a new world's height record of 11, 152feet was set up by Captain Felix at Etampes, while on the 7th of themonth Renaux flew nearly 600 miles on a Maurice Farman machine in 12hours. Cody and Valentine were keeping interest alive in the Circuit ofBritain race, although this had long been won, by determinedly ploddingon at finishing the course. On September 9th, the first aerial post was tried between Hendon andWindsor, as an experiment in sending mails by aeroplane. Gustave Hamelflew from Hendon to Windsor and back in a strong wind. A few dayslater, Hamel went on strike, refusing to carry further mails unless thepromoters of the Aerial Postal Service agreed to pay compensation toHubert, who fractured both his legs on the 11th of the month whileengaged in aero postal work. The strike ended on September 25th, whenHamel resumed mail-carrying in consequence of the capitulation of thePostmaster-General, who agreed to set aside L500 as compensation toHubert. September also witnessed the completion in America of a flight acrossthe Continent, a distance of 2, 600 miles. The only competitor whocompleted the full distance was C. P. Rogers, who was disqualifiedthrough failing to comply with the time limit. Rogers needed so manyreplacements to his machine on the journey that, expressing it inAmerican fashion, he arrived with practically a dfferent aeroplane fromthat with which he started. With regard to the aerial postal service, analysis of the matter carriedand the cost of the service seemed to show that with a special charge ofone shilling for letters and sixpence for post cards, the revenue justbalanced the expenditure. It was not possible to keep to the time-tableas, although the trials were made in the most favourable season of theyear, aviation was not sufficiently advanced to admit of facing allweathers and complying with time-table regulations. French military aeroplane trials took place at Rheims in October, thenoteworthy machines being Antoinette, Farman, Nieuport, and Deperdussin. The tests showed the Nieuport monoplane with Gnome motor as first inposition; the Breguet biplane was second, and the Deperdussin monoplanesthird. The first five machines in order of merit were all engined withthe Gnome motor. The records quoted for 1911 form the best evidence that can be given ofadvance in design and performance during the year. It will be seen thatthe days of the giants were over; design was becoming more and morestandardised and aviation not so much a matter of individual courage andeven daring, as of the reliability of the machine and its engine. This was the first year in which the twin-engined aeroplane made itsappearance, and it was the year, too, in which flying may be said tohave grown so common that the 'meetings' which began with Rheims werehardly worth holding, owing to the fact that increase in height anddistance flown rendered it no longer necessary for a would-be spectatorof a flight to pay half a crown and enter an enclosure. Henceforth, flying as a spectacle was very little to be considered; its commercialaspects were talked of, and to a very slight degree exploited, but, moreand more, the fact that the aeroplane was primarily an engine of war, and the growing German menace against the peace of the world combinedto point the way of speediest development, and the arrangements for theBritish Military Trials to be held in August, 1912, showed that eventhe British War office was waking up to the potentialities of this newengine of war. XVIII. A SUMMARY, TO 1914 Consideration of the events in the years immediately preceding the Warmust be limited to as brief a summary as possible, this not only becausethe full history of flying achievements is beyond the compass of anysingle book, but also because, viewing the matter in perspective, theyears 1903-1911 show up as far more important as regards both design andperformance. From 1912 to August of 1914, the development of aeronauticswas hindered by the fact that it had not progressed far enough to forma real commercial asset in any country. The meetings which drew vastconcourses of people to such places as Rheims and Bournemouth may havebeen financial successes at first, but, as flying grew more common anddistances and heights extended, a great many people found it other thanworth while to pay for admission to an aerodrome. The business of takingup passengers for pleasure flights was not financially successful, and, although schemes for commercial routes were talked of, the aeroplane wasnot sufficiently advanced to warrant the investment of hard cash inany of these projects. There was a deadlock; further developmentwas necessary in order to secure financial aid, and at the same timefinancial aid was necessary in order to secure further development. Consequently, neither was forthcoming. This is viewing the matter in a broad and general sense; there werefirms, especially in France, but also in England and America, whichlooked confidently for the great days of flying to arrive, and regardedtheir sunk capital as investment which would eventually bring its duereturn. But when one looks back on those years, the firms in questionstand out as exceptions to the general run of people, who regardedaeronautics as something extremely scientific, exceedingly dangerous, and very expensive. The very fame that was attained by such pilots asbecame casualties conduced to the advertisement of every death, and thedangers attendant on the use of heavier-than-air machines became greatlyexaggerated; considering the matter as one of number of miles flown, even in the early days, flying exacted no more toll in human life thandid railways or road motors in the early stages of their development. But to take one instance, when C. S. Rolls was killed at Bournemouth byreason of a faulty tail-plane, the fact was shouted to the whole worldwith almost as much vehemence as characterised the announcement of theTitanic sinking in mid-Atlantic. Even in 1911 the deadlock was apparent; meetings were falling off inattendance, and consequently in financial benefit to the promoters;there remained, however, the knowledge--for it was proved pastquestion--that the aeroplane in its then stage of development was anecessity to every army of the world. France had shown this by the morethan interest taken by the French Government in what had developed intoan Air Section of the French army; Germany, of course, was hypnotised byCount Zeppelin and his dirigibles, to say nothing of the Parsevals whichhad been proved useful military accessories; in spite of this, it wasrealised in Germany that the aeroplane also had its place in militaryaffairs. England came into the field with the military aeroplane trialsof August 1st to 15th, 1912, barely two months after the founding of theRoyal Flying Corps. When the R. F. C. Was founded--and in fact up to two years after itsfounding--in no country were the full military potentialities of theaeroplane realised; it was regarded as an accessory to cavalry forscouting more than as an independent arm; the possibilities of bombingwere very vaguely considered, and the fact that it might be possible toshoot from an aeroplane was hardly considered at all. The conditions ofthe British Military Trials of 1912 gave to the War office the optionof purchasing for L1, 000 any machine that might be awarded a prize. Machines were required, among other things, to carry a useful load of350 lbs. In addition to equipment, with fuel and oil for 4 1/2-hours;thus loaded, they were required to fly for 3 hours, attaining analtitude of 4, 500 feet, maintaining a height of 1, 500 feet for 1 hour, and climbing 1, 000 feet from the ground at a rate of 200 feet perminute, 'although 300 feet per minute is desirable. ' They had to attaina speed of not less than 55 miles per hour in a calm, and be able toplane down to the ground in a calm from not more than 1, 000 feet withengine stopped, traversing 6, 000 feet horizontal distance. For thosedays, the landing demands were rather exacting; the machine should beable to rise without damage from long grass, clover, or harrowed land, in 100 yards in a calm, and should be able to land without damage on anycultivated ground, including rough ploughed land, and, when landing onsmooth turf in a calm, be able to pull up within 75 yards of the pointof first touching the ground. It was required that pilot and observershould have as open a view as possible to front and flanks, and theyshould be so shielded from the wind as to be able to communicate witheach other. These are the main provisions out of the set of conditionslaid down for competitors, but a considerable amount of leniency wasshown by the authorities in the competition, who obviously wished to tryout every machine entered and see what were its capabilities. The beginning of the competition consisted in assembling the machinesagainst time from road trim to flying trim. Cody's machine, which wasthe only one to be delivered by air, took 1 hour and 35 minutes toassemble; the best assembling time was that of the Avro, which was gotinto flying trim in 14 minutes 30 seconds. This machine came to griefwith Lieut. Parke as pilot, on the 7th, through landing at very highspeed on very bad ground; a securing wire of the under-carriage broke inthe landing, throwing the machine forward on to its nose and then overon its back. Parke was uninjured, fortunately; the damaged machine wassent off to Manchester for repair and was back again on the 16th ofAugust. It is to be noted that by this time the Royal Aircraft Factory wasbuilding aeroplanes of the B. E. And F. E. Types, but at the same time itis also to be noted that British military interest in engines was notsufficient to bring them up to the high level attained by the planes, and it is notorious that even the outbreak of war found Englandincapable of providing a really satisfactory aero engine. In the 1912Trials, the only machines which actually completed all their tests werethe Cody biplane, the French Deperdussin, the Hanriot, two Bleriots anda Maurice Farman. The first prize of L4, 000, open to all the world, went to F. S. Cody's British-built biplane, which complied with allthe conditions of the competition and well earned its officialacknowledgment of supremacy. The machine climbed at 280 feet per minuteand reached a height of 5, 000 feet, while in the landing test, in spiteof its great weight and bulk, it pulled up on grass in 56 yards. Thetotal weight was 2, 690 lbs. When fully loaded, and the total area ofsupporting surface was 500 square feet; the motive power was suppliedby a six-cylinder 120 horsepower Austro-Daimler engine. The second prizewas taken by A. Deperdussin for the French-built Deperdussin monoplane. Cody carried off the only prize awarded for a British-built plane, this being the sum of L1, 000, and consolation prizes of L500 each wereawarded to the British Deperdussin Company and The British and ColonialAeroplane Company, this latter soon to become famous as makers of theBristol aeroplane, of which the war honours are still fresh in men'sminds. While these trials were in progress Audemars accomplished the firstflight between Paris and Berlin, setting out from Issy early in themorning of August 18th, landing at Rheims to refill his tanks within anhour and a half, and then coming into bad weather which forced himto land successively at Mezieres, Laroche, Bochum, and finally nearlyGersenkirchen, where, owing to a leaky petrol tank, the attempt to winthe prize offered for the first flight between the two capitals had tobe abandoned after 300 miles had been covered, as the time limit wasdefinitely exceeded. Audemars determined to get through to Berlin, andset off at 5 in the morning of the 19th, only to be brought down by fog;starting off again at 9. 15 he landed at Hanover, was off again at 1. 35, and reached the Johannisthal aerodrome in the suburbs of Berlin at 6. 48that evening. As early as 1910 the British Government possessed some ten aeroplanes, and in 1911 the force developed into the Army Air Battalion, with theaeroplanes under the control of Major J. H. Fulton, R. F. A. Toward theend of 1911 the Air Battalion was handed over to (then) Brig. -Gen. D. Henderson, Director of Military Training. On June 6th, 1912, the RoyalFlying Corps was established with a military wing under Major F. H. Sykes and a naval wing under Commander C. R. Samson. A joint Naval andMilitary Flying School was established at Upavon with Captain GodfreyM. Paine, R. N. , as Commandant and Major Hugh Trenchard as AssistantCommandant. The Royal Aircraft Factory brought out the B. E. And F. E. Types of biplane, admittedly superior to any other British design of theperiod, and an Aircraft Inspection Department was formed under Major J. H. Fulton. The military wing of the R. F. C. Was equipped almost entirelywith machines of Royal Aircraft Factory design, but the Navy preferredto develop British private enterprise by buying machines from privatefirms. On July 1st, 1914 the establishment of the Royal Naval AirService marked the definite separation of the military and naval sidesof British aviation, but the Central Flying School at Upavon continuedto train pilots for both services. It is difficult at this length of time, so far as the military wing wasconcerned, to do full justice to the spade work done by Major-GeneralSir David Henderson in the early days. Just before war broke out, British military air strength consisted officially of eight squadrons, each of 12 machines and 13 in reserve, with the necessary complement ofroad transport. As a matter of fact, there were three complete squadronsand a part of a fourth which constituted the force sent to France at theoutbreak of war. The value of General Henderson's work lies in the factthat, in spite of official stinginess and meagre supplies of every kind, he built up a skeleton organisation so elastic and so well thought outthat it conformed to war requirements as well as even the German plansfitted in with their aerial needs. On the 4th of August, 1914, thenominal British air strength of the military wing was 179 machines. Ofthese, 82 machines proceeded to France, landing at Amiens and flyingto Maubeuge to play their part in the great retreat with the BritishExpeditionary Force, in which they suffered heavy casualties both inpersonnel and machines. The history of their exploits, however, belongsto the War period. The development of the aeroplane between 1912 and 1914 can be judged bycomparison of the requirements of the British War Office in 1912 withthose laid down in an official memorandum issued by the War Officein February, 1914. This latter called for a light scout aeroplane, asingle-seater, with fuel capacity to admit of 300 miles range and aspeed range of from 50 to 85 miles per hour. It had to be able to climb3, 500 feet in five minutes, and the engine had to be so constructed thatthe pilot could start it without assistance. At the same time, a heaviertype of machine for reconnaissance work was called for, carrying fuelfor a 200 mile flight with a speed range of between 35 and 60 miles perhour, carrying both pilot and observer. It was to be equipped witha wireless telegraphy set, and be capable of landing over a 30 footvertical obstacle and coming to rest within a hundred yards' distancefrom the obstacle in a wind of not more than 15 miles per hour. A thirdrequirement was a heavy type of fighting aeroplane accommodating pilotand gunner with machine gun and ammunition, having a speed range ofbetween 45 and 75 miles per hour and capable of climbing 3, 500 feet in 8minutes. It was required to carry fuel for a 300 mile flight and to givethe gunner a clear field of fire in every direction up to 30 degrees oneach side of the line of flight. Comparison of these specifications withthose of the 1912 trials will show that although fighting, scouting, andreconnaissance types had been defined, the development of performancecompared with the marvellous development of the earlier years ofachieved flight was small. Yet the records of those years show that here and there an outstandingdesign was capable of great things. On the 9th September, 1912, Vedrines, flying a Deperdussin monoplane at Chicago, attained a speed of105 miles an hour. On August 12th, G. De Havilland took a passenger to aheight of 10, 560 feet over Salisbury Plain, flying a B. E. Biplane witha 70 horse-power Renault engine. The work of de Havilland may be said tohave been the principal influence in British military aeroplane design, and there is no doubt that his genius was in great measure responsiblefor the excellence of the early B. E. And F. E. Types. On the 31st May, 1913, H. G. Hawker, flying at Brooklands, reacheda height of 11, 450 feet on a Sopwith biplane engined with an 80horse-power Gnome engine. On June 16th, with the same type of machineand engine, he achieved 12, 900 feet. On the 2nd October, in the sameyear, a Grahame White biplane with 120 horse-power Austro-Daimlerengine, piloted by Louis Noel, made a flight of just under 20 minutescarrying 9 passengers. In France a Nieuport monoplane piloted by G. Legagneaux attained a height of 6, 120 metres, or just over 20, 070 feet, this being the world's height record. It is worthy of note that of theworld's aviation records as passed by the International AeronauticalFederation up to June 30th, 1914, only one, that of Noel, is credited toGreat Britain. Just as records were made abroad, with one exception, so were thereally efficient engines. In England there was the Green engine, but theoutbreak of war found the Royal Flying Corps with 80 horse-power Gnomes, 70 horse-power Renaults, and one or two Antoinette motors, but not oneBritish, while the Royal Naval Air Service had got 20 machines withengines of similar origin, mainly land planes in which the wheeledundercarriages had been replaced by floats. France led in development, and there is no doubt that at the outbreak of war, the French militaryaeroplane service was the best in the world. It was mainly composed ofMaurice Farman two-seater biplanes and Bleriot monoplanes--the lattertype banned for a period on account of a number of serious accidentsthat took place in 1912. America had its Army Aviation School, and employed Burgess-Wrightand Curtiss machines for the most part. In the pre-war years, oncethe Wright Brothers had accomplished their task, America's chiefaccomplishment consisted in the development of the 'Flying Boat, 'alternatively named with characteristic American clumsiness, 'TheHydro-Aeroplane. ' In February of 1911, Glenn Curtiss attached afloat to a machine similar to that with which he won the firstGordon-Bennett Air Contest and made his first flying boatexperiment. From this beginning he developed the boat form of bodywhich obviated the use and troubles of floats--his hydroplane becameits own float. Mainly owing to greater engine reliability the duration records steadilyincreased. By September of 1912 Fourny, on a Maurice Farman biplane, wasable to accomplish a distance of 628 miles without a landing, remainingin the air for 13 hours 17 minutes and just over 57 seconds. By 1914this was raised by the German aviator, Landemann, to 21 hours 48 3/4seconds. The nature of this last record shows that the factors in such arecord had become mere engine endurance, fuel capacity, and capacityof the pilot to withstand air conditions for a prolonged period, ratherthan any exceptional flying skill. Let these years be judged by the records they produced, and even thenthey are rather dull. The glory of achievement such as characterised thework of the Wright Brothers, of Bleriot, and of the giants of the earlydays, had passed; the splendid courage, the patriotism and devotionof the pilots of the War period had not yet come to being. There wasprogress, past question, but it was mechanical, hardly ever inspired. The study of climatic conditions was definitely begun and aeronauticalmeteorology came to being, while another development already noted wasthe fitting of wireless telegraphy to heavier-than-air machines, asinstanced in the British War office specification of February, 1914. These, however, were inevitable; it remained for the War to forcedevelopment beyond the inevitable, producing in five years that whichunder normal circumstances might easily have occupied fifty--theaeroplane of to-day; for, as already remarked, there was a deadlock, and any survey that may be made of the years 1912-1914, no matter howsuperficial, must take it into account with a view to retaining correctperspective in regard to the development of the aeroplane. There is one story of 1914 that must be included, however briefly, in any record of aeronautical achievement, since it demonstrates pastquestion that to Professor Langley really belongs the honour of havingachieved a design which would ensure actual flight, although the seriesof accidents which attended his experiments gave to the Wright Brothersthe honour of first leaving the earth and descending without accident ina power-driven heavier-than-air machine. In March, 1914, Glenn Curtisswas invited to send a flying boat to Washington for the celebrationof 'Langley Day, ' when he remarked, 'I would like to put the Langleyaeroplane itself in the air. ' In consequence of this remark, SecretaryWalcot of the Smithsonian Institution authorised Curtiss to re-canvasthe original Langley aeroplane and launch it either under its own poweror with a more recent engine and propeller. Curtiss completed this, andhad the machine ready on the shores of Lake Keuka, Hammondsport, N. Y. , by May. The main object of these renewed trials was to show whether theoriginal Langley machine was capable of sustained free flight with apilot, and a secondary object was to determine more fully the advantagesof the tandem monoplane type; thus the aeroplane was first flownas nearly as possible in its original condition, and then with suchmodifications as seemed desirable. The only difference made for thefirst trials consisted in fitting floats with connecting trusses;the steel main frame, wings, rudders, engine, and propellers weresubstantially as they had been in 1903. The pilot had the same seatunder the main frame and the same general system of control. He couldraise or lower the craft by moving the rear rudder up and down; he couldsteer right or left by moving the vertical rudder. He had no aileronsnor wing-warping mechanism, but for lateral balance depended on thedihedral angle of the wings and upon suitable movements of his weight orof the vertical rudder. After the adjustments for actual flight had been made in the Curtissfactory, according to the minute descriptions contained in the LangleyMemoir on Mechanical Flight, the aeroplane was taken to the shore ofLake Keuka, beside the Curtiss hangars, and assembled for launching. Ona clear morning (May 28th) and in a mild breeze, the craft was liftedon to the water by a dozen men and set going, with Mr Curtiss at thesteering wheel, esconced in the little boat-shaped car under the forwardpart of the frame. The four-winged craft, pointed somewhat across thewind, went skimming over the waveless, then automatically headed intothe wind, rose in level poise, soared gracefully for 150 feet, andlanded softly on the water near the shore. Mr Curtiss asserted that hecould have flown farther, but, being unused to the machine, imaginedthat the left wings had more resistance than the right. The truth isthat the aeroplane was perfectly balanced in wing resistance, but turnedon the water like a weather vane, owing to the lateral pressure onits big rear rudder. Hence in future experiments this rudder was madeturnable about a vertical axis, as well as about the horizontal axisused by Langley. Henceforth the little vertical rudder under the framewas kept fixed and inactive. [*] That the Langley aeroplane was subsequently fitted with an 80horse-power Curtiss engine and successfully flown is of little interestin such a record as this, except for the fact that with the weightnearly doubled by the new engine and accessories the machine flewsuccessfully, and demonstrated the perfection of Langley's design bystanding the strain. The point that is of most importance is that thedesign itself proved a success and fully vindicated Langley's work. At the same time, it would be unjust to pass by the fact of the flightwithout according to Curtiss due recognition of the way in which he paidtribute to the genius of the pioneer by these experiments. [*] Smithsonian Publications No. 2329. XIX. THE WAR PERIOD--I Full record of aeronautical progress and of the accomplishments ofpilots in the years of the War would demand not merely a volume, but acomplete library, and even then it would be barely possible to pay fulltribute to the heroism of pilots of the war period. There are namesconnected with that period of which the glory will not fade, names suchas Bishop, Guynemer, Boelcke, Ball, Fonck, Immelmann, and many othersthat spring to mind as one recalls the 'Aces' of the period. Inaddition to the pilots, there is the stupendous development of themachines--stupendous when the length of the period in which it wasachieved is considered. The fact that Germany was best prepared in the matter ofheavier-than-air service machines in spite of the German faith in thedirigible is one more item of evidence as to who forced hostilities. The Germans came into the field with well over 600 aeroplanes, mainlytwo-seaters of standardised design, and with factories back in theFatherland turning out sufficient new machines to make good thelosses. There were a few single-seater scouts built for speed, and thetwo-seater machines were all fitted with cameras and bomb-dropping gear. Manoeuvres had determined in the German mind what should be the uses ofthe air fleet; there was photography of fortifications and field works;signalling by Very lights; spotting for the guns, and scouting for newsof enemy movements. The methodical German mind had arranged all thisbeforehand, but had not allowed for the fact that opponents might takecounter-measures which would upset the over-perfect mechanism of the airservice just as effectually as the great march on Paris was countered bythe genius of Joffre. The French Air Force at the beginning of the War consisted of upwards of600 machines. These, unlike the Germans, were not standardised, but wereof many and diverse types. In order to get replacements quickly enough, the factories had to work on the designs they had, and thus for along time after the outbreak of hostilities standardisation was animpossibility. The versatility of a Latin race in a measure compensatedfor this; from the outset, the Germans tried to overwhelm the FrenchAir Force, but failed, since they had not the numerical superiority, nor--this equally a determining factor--the versatility and resourceof the French pilots. They calculated on a 50 per cent superiority toensure success; they needed more nearly 400 per cent, for the Germanfought to rule, avoiding risks whenever possible, and definitelyinstructed to save both machines and pilots wherever possible. Frenchpilots, on the other hand, ran all the risks there were, got newsof German movements, bombed the enemy, and rapidly worked up a veryrespectable antiaircraft force which, whatever it may have accomplishedin the way of hitting German planes, got on the German pilots' nerves. It has already been detailed how Britain sent over 82 planes as itscontribution to the military aerial force of 1914. These consisted ofFarman, Caudron, and Short biplanes, together with Bleriot, Deperdussinand Nieuport monoplanes, certain R. A. F. Types, and other machines ofwhich even the name barely survives--the resourceful Yankee entitlesthem 'orphans. ' It is on record that the work of providing spares mighthave been rather complicated but for the fact that there were none. There is no doubt that the Germans had made study of aerialmilitary needs just as thoroughly as they had perfected their groundorganisation. Thus there were 21 illuminated aircraft stations inGermany before the War, the most powerful being at Weimar, where arevolving electric flash of over 27 million candle-power was located. Practically all German aeroplane tests in the period immediatelypreceding the War were of a military nature, and quite a number ofreliability tests were carried out just on the other side of the Frenchfrontier. Night flying and landing were standardised items in the Germanpilot's course of instruction while they were still experimental inother countries, and a system of signals was arranged which rendered theinstructional course as perfect as might be. The Belgian contribution consisted of about twenty machines fit foractive service and another twenty which were more or less useful astraining machines. The material was mainly French, and the Belgianpilots used it to good account until German numbers swamped them. France, and to a small extent England, kept Belgian aviators suppliedwith machines throughout the War. The Italian Air Fleet was small, and consisted of French machinestogether with a percentage of planes of Italian origin, of which thedesign was very much a copy of French types. It was not until the Warwas nearing its end that the military and naval services relied moreon the home product than on imports. This does not apply to engines, however, for the F. I. A. T. And S. C. A. T. Were equal to practically anyengine of Allied make, both in design and construction. Russia spent vast sums in the provision of machines: the giant Sikorskybiplane, carrying four 100 horsepower Argus motors, was designed bya young Russian engineer in the latter part of 1913, and in its earlytrials it created a world's record by carrying seven passengers for1 hour 54 minutes. Sikorsky also designed several smaller machines, tractor biplanes on the lines of the British B. E. Type, which werevery successful. These were the only home productions, and the importsconsisted mainly of French aeroplanes by the hundred, which got asfar as the docks and railway sidings and stayed there, while Germaninfluence and the corruption that ruined the Russian Army helped to losethe War. A few Russian aircraft factories were got into operation ashostilities proceeded, but their products were negligible, and it is noton record that Russia ever learned to manufacture a magneto. The United States paid tribute to British efficiency by adopting theBritish system of training for its pilots; 500 American cadets weretrained at the School of Military Aeronautics at oxford, in order toform a nucleus for the American aviation schools which were subsequentlyset up in the United States and in France. As regards production ofcraft, the designing of the Liberty engine and building of over 20, 000aeroplanes within a year proves that America is a manufacturing country, even under the strain of war. There were three years of struggle for aerial supremacy, the combatantsbeing England and France against Germany, and the contest was neckand neck all the way. Germany led at the outset with the standardisedtwo-seater biplanes manned by pilots and observers, whose trainingwas superior to that afforded by any other nation, while the machinesthemselves were better equipped and fitted with accessories. All theearly German aeroplanes were designated Taube by the uninitiated, andwere formed with swept-back, curved wings very much resembling the wingsof a bird. These had obvious disadvantages, but the standardisationof design and mass production of the German factories kept them in thefield for a considerable period, and they flew side by side with tractorbiplanes of improved design. For a little time, the Fokker monoplanebecame a definite threat both to French and British machines. It wasan improvement on the Morane French monoplane, and with a high-poweredengine it climbed quickly and flew fast, doing a good deal of damage fora brief period of 1915. Allied design got ahead of it and finally droveit out of the air. German equipment at the outset, which put the Allies at a disadvantage, included a hand-operated magneto engine-starter and a small independentscrew which, mounted on one of the main planes, drove the dynamo usedfor the wireless set. Cameras were fitted on practically every machine;equipment included accurate compasses and pressure petrol gauges, speedand height recording instruments, bomb-dropping fittings and sectionalradiators which facilitated repairs and gave maximum engine efficiencyin spite of variations of temperature. As counter to these, the Alliedpilots had resource amounting to impudence. In the early days theycarried rifles and hand grenades and automatic pistols. They loadedtheir machines down, often at their own expense, with accessories andfittings until their aeroplanes earned their title of Christmas trees. They played with death in a way that shocked the average German pilotof the War's early stages, declining to fight according to rule andindulging in the individual duels of the air which the German hated. As Sir John French put it in one of his reports, they established apersonal ascendancy over the enemy, and in this way compensated fortheir inferior material. French diversity of design fitted in well with the initiative andresource displayed by the French pilots. The big Caudron type was theideal bomber of the early days; Farman machines were excellent forreconnaissance and artillery spotting; the Bleriots proved excellentas fighting scouts and for aerial photography; the Nieuports made goodfighters, as did the Spads, both being very fast craft, as were theMorane-Saulnier monoplanes, while the big Voisin biplanes rivalled theCaudron machines as bombers. The day of the Fokker ended when the British B. E. 2. C. Aeroplane cameto France in good quantities, and the F. E. Type, together with the DeHavilland machines, rendered British aerial superiority a certainty. Germany's best reply--this was about 1916--was the Albatross biplane, which was used by Captain Baron von Richthofen for his famous travellingcircus, manned by German star pilots and sent to various parts of theline to hearten up German troops and aviators after any specially badstrafe. Then there were the Aviatik biplane and the Halberstadt fightingscout, a cleanly built and very fast machine with a powerful engine withwhich Germany tried to win back superiority in the third year of theWar, but Allied design kept about three months ahead of that of theenemy, once the Fokker had been mastered, and the race went on. Spadsand Bristol fighters, Sopwith scouts and F. E. 's played their part in therace, and design was still advancing when peace came. The giant twin-engined Handley-Page bomber was tried out, provedefficient, and justly considered better than anything of its kind thathad previously taken the field. Immediately after the conclusion of itstrials, a specimen of the type was delivered intact at Lille for theGermans to copy, the innocent pilot responsible for the delivery doingsome great disservice to his own cause. The Gotha Wagon-Fabrik Firmimmediately set to work and copied the Handley-Page design, producingthe great Gotha bombing machine which was used in all the later raids onEngland as well as for night work over the Allied lines. How the War advanced design may be judged by comparison of the militaryrequirements given for the British Military Trials of 1912, withperformances of 1916 and 1917, when the speed of the faster machines hadincreased to over 150 miles an hour and Allied machines engaged enemyaircraft at heights ranging up to 22, 000 feet. All pre-war records ofendurance, speed, and climb went by the board, as the race for aerialsuperiority went on. Bombing brought to being a number of crude devices in the first year ofthe War. Allied pilots of the very early days carried up bombs packedin a small box and threw them over by hand, while, a little later, thebombs were strung like apples on wings and undercarriage, so thatthe pilot who did not get rid of his load before landing risked anexplosion. Then came a properly designed carrying apparatus, crude butfairly efficient, and with 1916 development had proceeded as far as theproper bomb-racks with releasing gear. Reconnaissance work developed, so that fighting machines went as escortto observing squadrons and scouting operations were undertaken up to 100miles behind the enemy lines; out of this grew the art of camouflage, when ammunition dumps were painted to resemble herds of cows, guns werescreened by foliage or painted to merge into a ground scheme, and manyother schemes were devised to prevent aerial observation. Troops weremoved by night for the most part, owing to the keen eyes of the airpilots and the danger of bombs, though occasionally the aviator had hischance. There is one story concerning a British pilot who, on returningfrom a reconnaissance flight, observed a German Staff car on the roadunder him; he descended and bombed and machine--gunned the car until theGerman General and his chauffeur abandoned it, took to their heels, andran like rabbits. Later still, when Allied air superiority was assured, there came the phase of machine-gunning bodies of enemy troops from theair. Disregarding all antiaircraft measures, machines would sweep downand throw battalions into panic or upset the military traffic along aroad, demoralising a battery or a transport train and causing as muchdamage through congestion of traffic as with their actual machine-gunfire. Aerial photography, too, became a fine art; the ordinary longfocus cameras were used at the outset with automatic plate changers, butlater on photographing aeroplanes had cameras of wide angle lens typebuilt into the fuselage. These were very simply operated, one leverregistering the exposure and changing the plate. In many cases, aerialphotographs gave information which the human eye had missed, and it isnoteworthy that photographs of ground showed when troops had marchedover it, while the aerial observer was quite unable to detect the marksleft by their passing. Some small mention must be made of seaplane activities, which, roundthe European coasts involved in the War, never ceased. The submarinecampaign found in the spotting seaplane its greatest deterrent, and itis old news now how even the deeply submerged submarines were easilypicked out for destruction from a height and the news wirelessed fromseaplane to destroyer, while in more than one place the seaplane itselffinished the task by bomb dropping. It was a seaplane that gave AdmiralBeatty the news that the whole German Fleet was out before the JutlandBattle, news which led to a change of plans that very nearly broughtabout the destruction of Germany's naval power. For the most part, theseaplanes of the War period were heavier than the land machines and, inthe opinion of the land pilots, were slow and clumsy things to fly. Thiswas inevitable, for their work demanded more solid building and greaterreliability. To put the matter into Hibernian phrase, a forced landingat sea is a much more serious matter than on the ground. Thus there wasneed for greater engine power, bigger wingspread to support the floats, and fuel tanks of greater capacity. The flying boats of the laterWar period carried considerable crews, were heavily armed, capable ofwithstanding very heavy weather, and carried good loads of bombs onlong cruises. Their work was not all essentially seaplane work, for theR. N. A. S. Was as well known as hated over the German airship sheds inBelgium and along the Flanders coast. As regards other theatres of War, they rendered valuable service from the Dardanelles to the Rufiji River, at this latter place forming a principal factor in the destruction ofthe cruiser Konigsberg. Their spotting work at the Dardanelles forthe battleships was responsible for direct hits from 15 in. Guns oninvisible targets at ranges of over 12, 000 yards. Seaplane pilots werebombing specialists, including among their targets army headquarters, ammunition dumps, railway stations, submarines and their bases, docks, shipping in German harbours, and the German Fleet at Wilhelmshaven. Dunkirk, a British seaplane base, was a sharp thorn in the German side. Turning from consideration of the various services to the exploits ofthe men composing them, it is difficult to particularise. A certaininevitable prejudice even at this length of time leads one to discountthe valour of pilots in the German Air Service, but the names ofBoelcke, von Richthofen, and Immelmann recur as proof of the couragethat was not wanting in the enemy ranks, while, however much we maydecry the Gotha raids over the English coast and on London, there is nodoubt that the men who undertook these raids were not deficient in theform of bravery that is of more value than the unthinking valour ofa minute which, observed from the right quarter, wins a militarydecoration. Yet the fact that the Allied airmen kept the air at all in the earlydays proved on which side personal superiority lay, for they wereoutnumbered, out-manoeuvred, and faced by better material than anythat they themselves possessed; yet they won their fights or died. Thestories of their deeds are endless; Bishop, flying alone and meetingseven German machines and crashing four; the battle of May 5th, 1915, when five heroes fought and conquered twenty-seven German machines, ranging in altitude between 12, 000 and 3, 000 feet, and continuing theextraordinary struggle from five until six in the evening. CaptainAizlewood, attacking five enemy machines with such reckless speed thathe rammed one and still reached his aerodrome safely--these are items ina long list of feats of which the character can only be realised whenit is fully comprehended that the British Air Service accounted for some8, 000 enemy machines in the course of the War. Among the French therewas Captain Guynemer, who at the time of his death had brought downfifty-four enemy machines, in addition to many others of which thedestruction could not be officially confirmed. There was Fonck, whobrought down six machines in one day, four of them within two minutes. There are incredible stories, true as incredible, of shattered mencarrying on with their work in absolute disregard of physical injury. Major Brabazon Rees, V. C. , engaged a big German battle-plane inSeptember of 1915 and, single-handed, forced his enemy out of action. Later in his career, with a serious wound in the thigh from which bloodwas pouring, he kept up a fight with an enemy formation until he had nota round of ammunition left, and then returned to his aerodrome to gethis wound dressed. Lieutenants Otley and Dunning, flying in the Balkans, engaged a couple of enemy machines and drove them off, but not untiltheir petrol tank had got a hole in it and Dunning was dangerouslywounded in the leg. Otley improvised a tourniquet, passed it to Dunning, and, when the latter had bandaged himself, changed from the observer'sto the pilot's seat, plugged the bullet hole in the tank with his thumband steered the machine home. These are incidents; the full list has not been, and can never berecorded, but it goes to show that in the pilot of the War period therecame to being a new type of humanity, a product of evolution whichfitted a certain need. Of such was Captain West, who, engaging hostiletroops, was attacked by seven machines. Early in the engagement, one ofhis legs was partially severed by an explosive bullet and fell powerlessinto the controls, rendering the machine for the time unmanageable. Lifting his disabled leg, he regained control of the machine, andalthough wounded in the other leg, he manoeuvred his machine soskilfully that his observer was able to get several good bursts into theenemy machines, driving them away. Then, desperately wounded as hewas, Captain West brought the machine over to his own lines and landedsafely. He fainted from loss of blood and exhaustion, but on regainingconsciousness, insisted on writing his report. Equal to this was theexploit of Captain Barker, who, in aerial combat, was wounded in theright and left thigh and had his left arm shattered, subsequentlybringing down an enemy machine in flames, and then breaking throughanother hostile formation and reaching the British lines. In recalling such exploits as these, one is tempted on and on, for itseems that the pilots rivalled each other in their devotion to duty, this not confined to British aviators, but common practically to allservices. Sufficient instances have been given to show the nature of thework and the character of the men who did it. The rapid growth of aerial effort rendered it necessary in January of1915 to organise the Royal Flying Corps into separate wings, and inOctober of the same year it was constituted in Brigades. In 1916 theAir Board was formed, mainly with the object of co-ordinating effortand ensuring both to the R. N. A. S. And to the R. F. C. Adequate supplies ofmaterial as far as construction admitted. Under the presidency of LordCowdray, the Air Board brought about certain reforms early in 1917, and in November of that year a separate Air Ministry was constituted, separating the Air Force from both Navy and Army, and rendering it anindependent force. On April 1st, 1918, the Royal Air Force came intoexistence, and unkind critics in the Royal Flying Corps remarked on theappropriateness of the date. At the end of the War, the personnel of theRoyal Air Force amounted to 27, 906 officers, and 263, 842 other ranks. Contrast of these figures with the number of officers and men who tookthe field in 1914 is indicative of the magnitude of British aerialeffort in the War period. XX. THE WAR PERIOD--II There was when War broke out no realisation on the part of the BritishGovernment of the need for encouraging the enterprise of privatebuilders, who carried out their work entirely at their-own cost. Theimportance of a supply of British-built engines was realised before theWar, it is true, and a competition was held in which a prize of L5, 000was offered for the best British engine, but this awakening was so latethat the R. F. C. Took the field without a single British power plant. Although Germany woke up equally late to the need for home producedaeroplane engines, the experience gained in building engines fordirigibles sufficed for the production of aeroplane power plants. TheMercedes filled all requirements together with the Benz and the Maybach. There was a 225 horsepower Benz which was very popular, as were the 100horse-power and 170 horse-power Mercedes, the last mentioned fitted tothe Aviatik biplane of 1917. The Uberursel was a copy of the Gnome andsupplied the need for rotary engines. In Great Britain there were a number of aeroplane constructing firmsthat had managed to emerge from the lean years 1912-1913 withsufficient manufacturing plant to give a hand in making up the leeway ofconstruction when War broke out. Gradually the motor-car firms camein, turning their body-building departments to plane and fuselageconstruction, which enabled them to turn out the complete planes enginedand ready for the field. The coach-building trade soon joined in andcame in handy as propeller makers; big upholstering and furniture firmsand scores of concerns that had never dreamed of engaging in aeroplaneconstruction were busy on supplying the R. F. C. By 1915 hundreds ofdifferent firms were building aeroplanes and parts; by 1917 the numberhad increased to over 1, 000, and a capital of over a million pounds fora firm that at the outbreak of War had employed a score or so of handswas by no means uncommon. Women and girls came into the work, moreespecially in plane construction and covering and doping, though theytook their place in the engine shops and proved successful at acetylenewelding and work at the lathes. It was some time before Britain was ableto provide its own magnetos, for this key industry had been left inthe hands of the Germans up to the outbreak of War, and the 'Bosch' wasadmittedly supreme--even now it has never been beaten, and can only beequalled, being as near perfection as is possible for a magneto. One of the great inventions of the War was the synchronisation ofengine-timing and machine gun, which rendered it possible to firethrough the blades of a propeller without damaging them, though thegrowing efficiency of the aeroplane as a whole and of its armament isa thing to marvel at on looking back and considering what was actuallyaccomplished. As the efficiency of the aeroplane increased, soanti-aircraft guns and range-finding were improved. Before the War anaeroplane travelling at full speed was reckoned perfectly safe at 4, 000feet, but, by the first month of 1915, the safe height had gone up to9, 000 feet, 7, 000 feet being the limit of rifle and machine gun bullettrajectory; the heavier guns were not sufficiently mobile to tackleaircraft. At that time, it was reckoned that effective aerialphotography ceased at 6, 000 feet, while bomb-dropping from 7, 000-8, 000feet was reckoned uncertain except in the case of a very large target. The improvement in anti-aircraft devices went on, and by May of 1916, anaeroplane was not safe under 15, 000 feet, while anti-aircraft shells hadfuses capable of being set to over 20, 000 feet, and bombing from 15, 000and 16, 000 feet was common. It was not till later that Allied pilotsdemonstrated the safety that lies in flying very near the ground, thisowing to the fact that, when flying swiftly at a very low altitude, themachine is out of sight almost before it can be aimed at. The Battle of the Somme and the clearing of the air preliminary to thatoperation brought the fighting aeroplane pure and simple with them. Formations of fighting planes preceded reconnaissance craft in orderto clear German machines and observation balloons out of the sky and towatch and keep down any further enemy formations that might attemptto interfere with Allied observation work. The German reply to thisconsisted in the formation of the Flying Circus, of which Captain Baronvon Richthofen's was a good example. Each circus consisted of a largeformation of speedy machines, built specially for fighting and mannedby the best of the German pilots. These were sent to attack at any pointalong the line where the Allies had got a decided superiority. The trick flying of pre-war days soon became an everyday matter; Pegoudastonished the aviation world before the War by first looping the loop, but, before three years of hostilities had elapsed, looping was part ofthe training of practically every pilot, while the spinning nose dive, originally considered fatal, was mastered, and the tail slide, whichconsisted of a machine rising nose upward in the air and falling back onits tail, became one of the easiest 'stunts' in the pilot's repertoire. Inherent stability was gradually improved, and, from 1916 onward, practically every pilot could carry on with his machine-gun or cameraand trust to his machine to fly itself until he was free to attend toit. There was more than one story of a machine coming safely to earthand making good landing on its own account with the pilot dead in hiscock-pit. Toward the end of the War, the Independent Air Force was formed as abranch of the R. A. F. With a view to bombing German bases and devotingits attention exclusively to work behind the enemy lines. Bombingoperations were undertaken by the R. N. A. S. As early as 1914-1915 againstCuxhaven, Dusseldorf, and Friedrichshavn, but the supply of material wasnot sufficient to render these raids continuous. A separate Brigade, the 8th, was formed in 1917 to harass the German chemical and ironindustries, the base being in the Nancy area, and this policy was foundso fruitful that the Independent Force was constituted on the 8th June, 1918. The value of the work accomplished by this force is demonstratedby the fact that the German High Command recalled twenty fightingsquadrons from the Western front to counter its activities, and, inaddition, took troops away from the fighting line in large numbers formanning anti-aircraft batteries and searchlights. The German press ofthe last year of the War is eloquent of the damage done in manufacturingareas by the Independent Force, which, had hostilities continued alittle longer, would have included Berlin in its activities. Formation flying was first developed by the Germans, who made use of itin the daylight raids against England in 1917. Its value was very soonrealised, and the V formation of wild geese was adopted, the leadertaking the point of the V and his squadron following on either side atdifferent heights. The air currents set up by the leading machines werethus avoided by those in the rear, while each pilot had a good viewof the leader's bombs, and were able to correct their own aim bythe bursts, while the different heights at which they flew renderedanti-aircraft gun practice less effective. Further, machines were ableto afford mutual protection to each other and any attacker would bemet by machine-gun fire from three or four machines firing on him fromdifferent angles and heights. In the later formations single-seaterfighters flew above the bombers for the purpose of driving off hostilecraft. Formation flying was not fully developed when the end of the Warbrought stagnation in place of the rapid advance in the strategy andtactics of military air work. XXI. RECONSTRUCTION The end of the War brought a pause in which the multitude of aircraftconstructors found themselves faced with the possible completestagnation of the industry, since military activities no longer demandedtheir services and the prospects of commercial flying were virtuallynil. That great factor in commercial success, cost of plant and upkeep, had received no consideration whatever in the War period, for armies donot count cost. The types of machines that had evolved from the Warwere very fast, very efficient, and very expensive, although the bombersshowed promise of adaptation to commercial needs, and, so far as othermachines were concerned, America had already proved the possibilities ofmail-carrying by maintaining a mail service even during the War period. A civil aviation department of the Air Ministry was formed in Februaryof 1919 with a Controller General of Civil Aviation at the head. Thiswas organised into four branches, one dealing with the survey andpreparation of air routes for the British Empire, one organisingmeteorological and wireless telegraphy services, one dealing with thelicensing of aerodromes, machines for passenger or goods carrying andcivilian pilots, and one dealing with publicity and transmission ofinformation generally. A special Act of Parliament 264 entitled 'The AirNavigation Acts, 1911-1919, ' was passed on February 27th, and commercialflying was officially permitted from May 1st, 1919. Meanwhile the great event of 1919, the crossing of the Atlantic by air, was gradually ripening to performance. In addition to the rigid airship, R. 34, eight machines entered for this flight, these being a Shortseaplane, Handley-Page, Martinsyde, Vickers-Vimy, and Sopwithaeroplanes, and three American flying boats, N. C. 1, N. C. 3, and N. C. 4. The Short seaplane was the only one of the eight which proposed to makethe journey westward; in flying from England to Ireland, before startingon the long trip to Newfoundland, it fell into the sea off the coast ofAnglesey, and so far as it was concerned the attempt was abandoned. The first machines to start from the Western end were the three Americanseaplanes, which on the morning of May 6th left Trepassy, Newfoundland, on the 1, 380 mile stage to Horta in the Azores. N. C. 1 and N. C. 3 gaveup the attempt very early, but N. C. 4, piloted by Lieut. -Commander Read, U. S. N. , made Horta on May 17th and made a three days' halt. On the 20ththe second stage of the journey to Ponta Delgada, a further 190 miles, was completed and a second halt of a week was made. On the 27th, themachine left for Lisbon, 900 miles distant, and completed the journey ina day. On the 30th a further stage of 340 miles took N. C. 4 on toFerrol, and the next day the last stage of 420 miles to Plymouth wasaccomplished. Meanwhile, H. G. Hawker, pilot of the Sopwith biplane, together withCommander Mackenzie Grieve, R. N. , his navigator, found the weathersufficiently auspicious to set out at 6. 48 p. M. On Sunday, May 18th, inthe hope of completing the trip by the direct route before N. C. 4 couldreach Plymouth. They set out from Mount Pearl aerodrome, St John's, Newfoundland, and vanished into space, being given up as lost, as Hamelwas lost immediately before the War in attempting to fly the NorthSea. There was a week of dead silence regarding their fate, but on thefollowing Sunday morning there was world-wide relief at the news thatthe plucky attempt had not ended in disaster, but both aviators had beenpicked up by the steamer Mary at 9. 30 a. M. On the morning of the 19th, while still about 750 miles short of the conclusion of their journey. Engine failure brought them down, and they planed down to the sea closeto the Mary to be picked up; as the vessel was not fitted with wireless, the news of their rescue could not be communicated until land wasreached. An equivalent of half the L10, 000 prize offered by the DailyMail for the non-stop flight was presented by the paper in recognitionof the very gallant attempt, and the King conferred the Air Force Crosson both pilot and navigator. Raynham, pilot of the Martinsyde competing machine, had the bad luck tocrash his craft twice in attempting to start before he got outside theboundary of the aerodrome. The Handley-Page machine was withdrawn fromthe competition, and, attempting to fly to America, was crashed on theway. The first non-stop crossing was made on June 14th-15th in 16 hours 27minutes, the speed being just over 117 miles per hour. The machine was aVickers-Vimy bomber, engined with two Rolls-Royce Eagle VIII's, pilotedby Captain John Alcock, D. S. C. , with Lieut. Arthur Whitten-Brown asnavigator. The journey was reported to be very rough, so much so attimes that Captain Alcock stated that they were flying upside down, andfor the greater part of the time they were out of sight of the sea. Bothpilot and navigator had the honour of knighthood conferred on them atthe conclusion of the journey. Meanwhile, commercial flying opened on May 8th (the official datewas May 1st) with a joy-ride service from Hounslow of Avro trainingmachines. The enterprise caught on remarkably, and the company extendedtheir activities to coastal resorts for the holiday season--at Blackpoolalone they took up 10, 000 passengers before the service was two monthsold. Hendon, beginning passenger flights on the same date, went in forexhibition and passenger flying, and on June 21st the aerial Derbywas won by Captain Gathergood on an Airco 4R machine with a Napier 450horse-power 'Lion' engine; incidentally the speed of 129. 3 miles perhour was officially recognised as constituting the world's record forspeed within a closed circuit. On July 17th a Fiat B. R. Biplane with a700 horse-power engine landed at Kenley aerodrome after having made anon-stop flight of 1, 100 miles. The maximum speed of this machine was160 miles per hour, and it was claimed to be the fastest machine inexistence. On August 25th a daily service between London and Paris wasinaugurated by the Aircraft Manufacturing Company, Limited, who ran amachine each way each day, starting at 12. 30 and due to arrive at 2. 45p. M. The Handley-Page Company began a similar service in Septemberof 1919, but ran it on alternate days with machines capable ofaccommodating ten passengers. The single fare in each case was fixed at15 guineas and the parcel rate at 7s. 6d. Per pound. Meanwhile, in Germany, a number of passenger services had been inoperation from the early part of the year; the Berlin-Weimar service wasestablished on February 5th and Berlin-Hamburg on March 1st, both formail and passenger carrying. Berlin-Breslau was soon added, but thefirst route opened remained most popular, 538 flights being made betweenits opening and the end of April, while for March and April combined, the Hamburg-Berlin route recorded only 262 flights. All three routeswere operated by a combine of German aeronautical firms entitled theDeutsch Luft Rederie. The single fare between Hamburg and Berlin was450 marks, between Berlin and Breslau 500 marks, and between Berlinand Weimar 450 marks. Luggage was carried free of charge, but variedaccording to the weight of the passenger, since the combined weight ofboth passenger and luggage was not allowed to exceed a certain limit. In America commercial flying had begun in May of 1918 with the mailservice between Washington, Philadelphia, and New York, which provedthat mail carrying is a commercial possibility, and also demonstratedthe remarkable reliability of the modern aeroplane by making 102complete flights out of a possible total of 104 in November, 1918, at acost of 0. 777 of a dollar per mile. By March of 1919 the cost per milehad gone up to 1. 28 dollars; the first annual report issued at theend of May showed an efficiency of 95. 6 per cent and the originalsix aeroplanes and engines with which the service began were still inregular use. In June of 1919 an American commercial firm chartered an aeroplane foremergency service owing to a New York harbour strike and found it souseful that they made it a regular service. The Travellers Companyinaugurated a passenger flying boat service between New York andAtlantic City on July 25th, the fare, inclusive of 35 lbs. Of luggage, being fixed at L25 each way. Five flights on the American continent up to the end of 1919 are worthyof note. On December 13th, 1918, Lieut. D. Godoy of the Chilian armyleft Santiago, Chili, crossed the Andes at a height of 19, 700 feetand landed at Mendoza, the capital of the wine-growing province ofArgentina. On April 19th, 1919, Captain E. F. White made the firstnon-stop flight between New York and Chicago in 6 hours 50 minutes ona D. H. 4 machine driven by a twelve-cylinder Liberty engine. Early inAugust Major Schroeder, piloting a French Lepere machine flying at aheight of 18, 400 feet, reached a speed of 137 miles per hour with aLiberty motor fitted with a super-charger. Toward the end of August, RexMarshall, on a Thomas-Morse biplane, starting from a height of 17, 000feet, made a glide of 35 miles with his engine cut off, restarting itwhen at a height of 600 feet above the ground. About a month later R. Rohlfe, piloting a Curtiss triplane, broke the height record by reaching34, 610 feet. XXII. 1919-20 Into the later months of 1919 comes the flight by Captain Ross-Smithfrom England to Australia and the attempt to make the Cape to Cairovoyage by air. The Australian Government had offered a prize of L10, 000for the first flight from England to Australia in a British machine, theflight to be accomplished in 720 consecutive hours. Ross-Smith, with hisbrother, Lieut. Keith Macpherson Smith, and two mechanics, left Hounslowin a Vickers-Vimy bomber with Rolls-Royce engine on November 12th andarrived at Port Darwin, North Australia, on the 10th December, havingcompleted the flight in 27 days 20 hours 20 minutes, thus having 51hours 40 minutes to spare out of the 720 allotted hours. Early in 1920 came a series of attempts at completing the journey by airbetween Cairo and the Cape. Out of four competitors Colonel Van Ryneveldcame nearest to making the journey successfully, leaving England ona standard Vickers-Vimy bomber with Rolls-Royce engines, identical indesign with the machine used by Captain Ross-Smith on the Englandto Australia flight. A second Vickers-Vimy was financed by the Timesnewspaper and a third flight was undertaken with a Handley-Page machineunder the auspices of the Daily Telegraph. The Air Ministry had alreadyprepared the route by means of three survey parties which cleared theaerodromes and landing grounds, dividing their journey into stages of200 miles or less. Not one of the competitors completed the course, butin both this and Ross-Smith's flight valuable data was gained inrespect of reliability of machines and engines, together with a mass ofmeteorological information. The Handley-Page Company announced in the early months of 1920 that theyhad perfected a new design of wing which brought about a twenty to fortyper cent improvement in lift rate in the year. When the nature of thedesign was made public, it was seen to consist of a division of thewing into small sections, each with its separate lift. A few days later, Fokker, the Dutch inventor, announced the construction of a machine inwhich all external bracing wires are obviated, the wings being of avery deep section and self-supporting. The value of these two inventionsremains to be seen so far as commercial flying is concerned. The value of air work in war, especially so far as the Colonialcampaigns in which British troops are constantly being engaged is inquestion, was very thoroughly demonstrated in a report issued earlyin 1920 with reference to the successful termination of the Somalilandcampaign through the intervention of the Royal Air Force, which betweenJanuary 21st and the 31st practically destroyed the Dervish force underthe Mullah, which had been a thorn in the side of Britain since 1907. Bombs and machine-guns did the work, destroying fortifications andbringing about the surrender of all the Mullah's following, with theexception of about seventy who made their escape. Certain records both in construction and performance had characterisedthe post-war years, though as design advances and comes nearer toperfection, it is obvious that records must get fewer and fartherbetween. The record aeroplane as regards size at the time of itsconstruction was the Tarrant triplane, which made its first--andlast--flight on May 28th, 1919. The total loaded weight was 30 tons, and the machine was fitted with six 400 horse-power engines; almostimmediately after the trial flight began, the machine pitched forwardon its nose and was wrecked, causing fatal injuries to Captains Dunnand Rawlings, who were aboard the machine. A second accident ofsimilar character was that which befell the giant seaplane known as theFelixstowe Fury, in a trial flight. This latter machine was intended tobe flown to Australia, but was crashed over the water. On May 4th, 1920, a British record for flight duration and usefulload was established by a commercial type Handley-Page biplane, which, carrying a load of 3, 690 lbs. , rose to a height of 13, 999 feet andremained in the air for 1 hour 20 minutes. On May 27th the French pilot, Fronval, flying at Villacoublay in a Morane-Saulnier type of biplanewith Le Rhone motor, put up an extraordinary type of record by loopingthe loop 962 times in 3 hours 52 minutes 10 seconds. Another record ofthe year of similar nature was that of two French fliers, Boussotrotand Bernard, who achieved a continuous flight of 24 hours 19 minutes 7seconds, beating the pre-war record of 21 hours 48 3/4 seconds set upby the German pilot, Landemann. Both these records are likely to stand, being in the nature of freaks, which demonstrate little beyond thereliability of the machine and the capacity for endurance on the part ofits pilots. Meanwhile, on February 14th, Lieuts. Masiero and Ferrarin left Rome onS. V. A. Ansaldo V. Machines fitted with 220 horse-power S. V. A. Motors. OnMay 30th they arrived at Tokio, having flown by way of Bagdad, Karachi, Canton, Pekin, and Osaka. Several other competitors started, two of whomwere shot down by Arabs in Mesopotamia. Considered in a general way, the first two years after the terminationof the Great European War form a period of transition in which thecommercial type of aeroplane was gradually evolved from the fightingmachine which was perfected in the four preceding years. There was aboutthis period no sense of finality, but it was as experimental, in itsown way, as were the years of progressing design which preceded the warperiod. Such commercial schemes as were inaugurated call for no morenote than has been given here; they have been experimental, and, withthe possible exception of the United States Government mail service, have not been planned and executed on a sufficiently large scale tofurnish reliable data on which to forecast the prospects of commercialaviation. And there is a school rapidly growing up which asserts thatthe day of aeroplanes is nearly over. The construction of the giantairships of to-day and the successful return flight of R34 acrossthe Atlantic seem to point to the eventual triumph, in spite of itsdisadvantages, of the dirigible airship. This is a hard saying for such of the aeroplane industry as survivedthe War period and consolidated itself, and it is but the saying of asection which bases its belief on the fact that, as was noted in thevery early years of the century, the aeroplane is primarily a warmachine. Moreover, the experience of the War period tended to discreditthe dirigible, since, before the introduction of helium gas, the inflammability of its buoyant factor placed it at an immensedisadvantage beside the machine dependent on the atmosphere itself forits lift. As life runs to-day, it is a long time since Kipling wrote his story ofthe airways of a future world and thrust out a prophecy that the bulkof the world's air traffic would be carried by gas-bag vessels. If theschool which inclines to belief in the dirigible is right in its belief, as it well may be, then the foresight was uncannily correct, not onlyin the matter of the main assumption, but in the detail with which thewriter embroidered it. On the constructional side, the history of the aeroplane is still somuch in the making that any attempt at a critical history would beunwise, and it is possible only to record fact, leaving it to the futurefor judgment to be passed. But, in a general way, criticism maybe advanced with regard to the place that aeronautics takes incivilisation. In the past hundred years, the world has made miraculouslyrapid strides materially, but moral development has not kept abreast. Conception of the responsibilities of humanity remains virtually in aposition of a hundred years ago; given a higher conception of life andits responsibilities, the aeroplane becomes the crowning achievementof that long series which James Watt inaugurated, the last step inintercommunication, the chain with which all nations are bound ina growing prosperity, surely based on moral wellbeing. Without suchconception of the duties as well as the rights of life, this lastachievement of science may yet prove the weapon that shall endcivilisation as men know it to-day, and bring this ultra-material age toa phase of ruin on which saner people can build a world more reasonableand less given to groping after purely material advancement. PART II. 1903-1920: PROGRESS IN DESIGN By Lieut. -Col. W. Lockwood Marsh I. THE BEGINNINGS Although the first actual flight of an aeroplane was made by the Wrightson December 17th 1903, it is necessary, in considering the progressof design between that period and the present day, to go back tothe earlier days of their experiments with 'gliders, ' which show thealterations in design made by them in their step-bystep progress to aflying machine proper, and give a clear idea of the stage at which theyhad arrived in the art of aeroplane design at the time of their firstflights. They started by carefully surveying the work of previous experimenters, such as Lilienthal and Chanute, and from the lesson of some of thefailures of these pioneers evolved certain new principles which wereembodied in their first glider, built in 1900. In the first place, instead of relying upon the shifting of the operator's body to obtainbalance, which had proved too slow to be reliable, they fitted in frontof the main supporting surfaces what we now call an 'elevator, ' whichcould be flexed, to control the longitudinal balance, from where theoperator lay prone upon the main supporting surfaces. The secondmain innovation which they incorporated in this first glider, and theprinciple of which is still used in every aeroplane in existence, wasthe attainment of lateral balance by warping the extremities of the mainplanes. The effect of warping or pulling down the extremity of the wingon one side was to increase its lift and so cause that side to rise. Inthe first two gliders this control was also used for steering to rightand left. Both these methods of control were novel for other than modelwork, as previous experimenters, such as Lilienthal and Pilcher, hadrelied entirely upon moving the legs or shifting the position of thebody to control the longitudinal and lateral motions of their gliders. For the main supporting surfaces of the glider the biplane system ofChanute's gliders was adopted with certain modifications, while thecurve of the wings was founded upon the calculations of Lilienthal as towind pressure and consequent lift of the plane. This first glider was tested on the Kill Devil Hill sand-hills in NorthCarolina in the summer of 1900 and proved at any rate the correctnessof the principles of the front elevator and warping wings, though itsdesigners were puzzled by the fact that the lift was less than theyexpected; whilst the 'drag'(as we call it), or resistance, was alsoconsiderably lower than their predictions. The 1901 machine was, inconsequence, nearly doubled in area--the lifting surface being increasedfrom 165 to 308 square feet--the first trial taking place on July 27th, 1901, again at Kill Devil Hill. It immediately appeared that somethingwas wrong, as the machine dived straight to the ground, and it was onlyafter the operator's position had been moved nearly a foot back fromwhat had been calculated as the correct position that the machine wouldglide--and even then the elevator had to be used far more strongly thanin the previous year's glider. After a good deal of thought the apparentsolution of the trouble was finally found. This consisted in the fact that with curved surfaces, while at largeangles the centre of pressure moves forward as the angle decreases, whena certain limit of angle is reached it travels suddenly backwards andcauses the machine to dive. The Wrights had known of this tendency fromLilienthal's researches, but had imagined that the phenomenon woulddisappear if they used a fairly lightly cambered--or curved--surfacewith a very abrupt curve at the front. Having discovered what appearedto be the cause they surmounted the difficulty by 'trussing down' thecamber of the wings, with the result that they at once got back tothe old conditions of the previous year and could control the machinereadily with small movements of the elevator, even being able to followundulations in the ground. They still found, however, that the lift wasnot as great as it should have been; while the drag remained, as inthe previous glider, surprisingly small. This threw doubt on previousfigures as to wind resistance and pressure on curved surfaces; butat the same time confirmed (and this was a most important result)Lilienthal's previously questioned theory that at small angles thepressure on a curved surface instead of being normal, or at right anglesto, the chord is in fact inclined in front of the perpendicular. Theresult of this is that the pressure actually tends to draw the machineforward into the wind--hence the small amount of drag, which had puzzledWilbur and Orville Wright. Another lesson which was learnt from these first two years ofexperiment, was that where, as in a biplane, two surfaces are superposedone above the other, each of them has somewhat less lift than it wouldhave if used alone. The experimenters were also still in doubt as to theefficiency of the warping method of controlling the lateral balanceas it gave rise to certain phenomena which puzzled them, the machineturning towards the wing having the greater angle, which seemed also totouch the ground first, contrary to their expectations. Accordingly, on returning to Dayton towards the end of 1901, they set themselves tosolve the various problems which had appeared and started on alengthy series of experiments to check the previous figures as to windresistance and lift of curved surfaces, besides setting themselvesto grapple with the difficulty of lateral control. They accordinglyconstructed for themselves at their home in Dayton a wind tunnel 16inches square by 6 feet long in which they measured the lift and 'drag'of more than two hundred miniature wings. In the course of these teststhey for the first time produced comparative results of the lift ofoblong and square surfaces, with the result that they re-discovered theimportance of 'aspect ratio'--the ratio of length to breadth of planes. As a result, in the next year's glider the aspect ration of the wingswas increased from the three to one of the earliest model to about sixto one, which is approximately the same as that used in the machinesof to-day. Further than that, they discussed the question of lateralstability, and came to the conclusion that the cause of the trouble wasthat the effect of warping down one wing was to increase the resistanceof, and consequently slow down, that wing to such an extent that itslift was reduced sufficiently to wipe out the anticipated increase inlift resulting from the warping. From this they deduced that if thespeed of the warped wing could be controlled the advantage of increasingthe angle by warping could be utilised as they originally intended. They therefore decided to fit a vertical fin at the rear which, if themachine attempted to turn, would be exposed more and more to the windand so stop the turning motion by offering increased resistance. As a result of this laboratory research work the third Wright glider, which was taken to Kill Devil Hill in September, 1902, was far moreefficient aerodynamically than either of its two predecessors, and wasfitted with a fixed vertical fin at the rear in addition to the movableelevator in front. According to Mr Griffith Brewer, [*] this third glidercontained 305 square feet of surface; though there may possibly be amistake here, as he states[**] the surface of the previous year's gliderto have been only 290 square feet, whereas Wilbur Wright himself[***]states it to have been 308 square feet. The matter is not, perhaps, savehistorically, of much importance, except that the gliders are believedto have been progressively larger, and therefore if we accept WilburWright's own figure of the surface of the second glider, the thirdmust have had a greater area than that given by Mr Griffith Brewer. Unfortunately, no evidence of the Wright Brothers themselves on thispoint is available. [*] Fourth Wilbur Wright Memorial Lecture, Aeronautical Journal, Vol. XX, No. 79, page 75. [**] Ibid. Page 73. [***] Ibid. Pp. 91 and 102. The first glide of the 1902, season was made on September 17th of thatyear, and the new machine at once showed itself an improvement on itspredecessors, though subsequent trials showed that the difficultyof lateral balance had not been entirely overcome. It was decided, therefore, to turn the vertical fin at the rear into a rudder by makingit movable. At the same time it was realised that there was a definiterelation between lateral balance and directional control, and the ruddercontrols and wing-warping wires were accordingly connected This endedthe pioneer gliding experiments of Wilbur and Orville Wright--thoughfurther glides were made in subsequent years--as the following year, 1903, saw the first power-driven machine leave the ground. To recapitulate--in the course of these original experiments the Wrightsconfirmed Lilienthal's theory of the reversal of the centre of pressureon cambered surfaces at small angles of incidence: they confirmed theimportance of high aspect ratio in respect to lift: they had evolved newand more accurate tables of lift and pressure on cambered surfaces:they were the first to use a movable horizontal elevator for controllingheight: they were the first to adjust the wings to different angles ofincidence to maintain lateral balance: and they were the first to usethe movable rudder and adjustable wings in combination. They now considered that they had gone far enough to justify them inbuilding a power-driven 'flier, ' as they called their first aeroplane. They could find no suitable engine and so proceeded to build forthemselves an internal combustion engine, which was designed to give8 horse-power, but when completed actually developed about 12-15horse-power and weighed 240 lbs. The complete machine weighed about750 lbs. Further details of the first Wright aeroplane are difficult toobtain, and even those here given should be received with some caution. The first flight was made on December 17th 1903, and lasted 12 seconds. Others followed immediately, and the fourth lasted 59 seconds, adistance of 852 feet being covered against a 20-mile wind. The following year they transferred operations to a field outsideDayton, Ohio (their home), and there they flew a somewhat larger andheavier machine with which on September 20th 1904, they completed thefirst circle in the air. In this machine for the first time the pilothad a seat; all the previous experiments having been carried out withthe operator lying prone on the lower wing. This was followed nextyear by another still larger machine, and on it they carried out manyflights. During the course of these flights they satisfied themselves asto the cause of a phenomenon which had puzzled them during the previousyear and caused them to fear that they had not solved the problemof lateral control. They found that on occasions--always when on aturn--the machine began to slide down towards the ground and that noamount of warping could stop it. Finally it was found that if the noseof the machine was tilted down a recovery could be effected; from whichthey concluded that what actually happened was that the machine, 'owingto the increased load caused by centrifugal force, ' had insufficientpower to maintain itself in the air and therefore lost speed until apoint was reached at which the controls became inoperative. In otherwords, this was the first experience of 'stalling on a turn, ' which is adanger against which all embryo pilots have to guard in the early stagesof their training. The 1905 machine was, like its predecessors, a biplane with a biplaneelevator in front and a double vertical rudder in rear. The span was 40feet, the chord of the wings being 6 feet and the gap between them aboutthe same. The total area was about 600 square feet which supporteda total weight of 925 lbs. ; while the motor was 12 to 15 horse-powerdriving two propellers on each side behind the main planes throughchains and giving the machine a speed of about 30 m. P. H. One ofthese chains was crossed so that the propellers revolved in oppositedirections to avoid the torque which it was feared would be set upif they both revolved the same way. The machine was not fitted with awheeled undercarriage but was carried on two skids, which also acted asoutriggers to carry the elevator. Consequently, a mechanical method oflaunching had to be evolved and the machine received initial velocityfrom a rail, along which it was drawn by the impetus provided by thefalling of a weight from a wooden tower or 'pylon. ' As a result of thisthe Wright aeroplane in its original form had to be taken back to itsstarting rail after each flight, and could not restart from the point ofalighting. Perhaps, in comparison with French machines of more or lesscontemporary date (evolved on independent lines in ignorance of theAmericans' work), the chief feature of the Wright biplane of 1905was that it relied entirely upon the skill of the operator for itsstability; whereas in France some attempt was being made, althoughperhaps not very successfully, to make the machine automatically stablelaterally. The performance of the Wrights in carrying a loading of some60 lbs. Per horse-power is one which should not be overlooked. The wingloading was about 1 1/2 lbs. Per square foot. About the same time that the Wrights were carrying out theirpower-driven experiments, a band of pioneers was quite independentlybeginning to approach success in France. In practically every case, however, they started from a somewhat different standpoint and tookas their basic idea the cellular (or box) kite. This form of kite, consisting of two superposed surfaces connected at each end by avertical panel or curtain of fabric, had proved extremely successful forman-carrying purposes, and, therefore, it was little wonder that severalminds conceived the idea of attempting to fly by fitting a seriesof box-kites with an engine. The first to achieve success was M. Santos-Dumont, the famous Brazilian pioneer-designer of airships, who, on November 12th, 1906, made several flights, the last of which covereda little over 700 feet. Santos-Dumont's machine consisted essentially oftwo box-kites, forming the main wings, one on each side of the body, inwhich the pilot stood, and at the front extremity of which was anothermovable box-kite to act as elevator and rudder. The curtains at the endswere intended to give lateral stability, which was further ensured bysetting the wings slightly inclined upwards from the centre, so thatwhen seen from the front they formed a wide V. This feature is stillto be found in many aeroplanes to-day and has come to be known as the'dihedral. ' The motor was at first of 24 horse-power, for which later a50 horse-power Antoinette engine was substituted; whilst a three-wheeledundercarriage was provided, so that the machine could start withoutexternal mechanical aid. The machine was constructed of bamboo andsteel, the weight being as low as 352 lbs. The span was 40 feet, thelength being 33 feet, with a total surface of main planes of 860 squarefeet. It will thus be seen--for comparison with the Wright machine--thatthe weight per horse-power (with the 50 horse-power engine) was only 7lbs. , while the wing loading was equally low at 1/2 lb. Per square foot. The main features of the Santos-Dumont machine were the box-kite form ofconstruction, with a dihedral angle on the main planes, and the forwardelevator which could be moved in any direction and therefore acted inthe same way as the rudder at the rear of the Wright biplane. It had asingle propeller revolving in the centre behind the wings and was fittedwith an undercarriage incorporated in the machine. The other chief French experimenters at this period were the VoisinFreres, whose first two machines--identical in form--were sold toDelagrange and H. Farman, which has sometimes caused confusion, the twopurchasers being credited with the design they bought. The Voisins, likethe Wrights, based their designs largely on the experimental work ofLilienthal, Langley, Chanute, and others, though they also carried outtests on the lifting properties of aerofoils in a wind tunnel of theirown. Their first machines, like those of Santos-Dumont, showed theeffects of experimenting with box-kites, some of which they had builtfor M. Ernest Archdeacon in 1904. In their case the machine, which wasagain a biplane, had, like both the others previously mentioned, anelevator in front--though in this case of monoplane form--and, as inthe Wright, a rudder was fitted in rear of the main planes. The Voisins, however, fitted a fixed biplane horizontal 'tail'--in an effort toobtain a measure of automatic longitudinal stability--between the twosurfaces of which the single rudder worked. For lateral stability theydepended entirely on end curtains between the upper and lowersurfaces of both the main planes and biplane tail surfaces. They, likeSantos-Dumont, fitted a wheeled undercarriage, so that the machinewas self-contained. The Voisin machine, then, was intended to beautomatically stable in both senses; whereas the Wrights deliberatelyproduced a machine which was entirely dependent upon the pilot'sskill for its stability. The dimensions of the Voisin may be given forcomparative purposes, and were as follows: Span 33 feet with a chord(width from back to front) of main planes of 6 1/2 feet, giving a totalarea of 430 square feet. The 50 horse-power Antoinette engine, whichwas enclosed in the body (or 'nacelle ') in the front of which the pilotsat, drove a propeller behind, revolving between the outriggers carryingthe tail. The total weight, including Farman as pilot, is given as 1, 540lbs. , so that the machine was much heavier than either of the others;the weight per horse-power being midway between the Santos-Dumontand the Wright at 31 lbs. Per square foot, while the wing loading wasconsiderably greater than either at 3 1/2 lbs. Per square foot. TheVoisin machine was experimented with by Farman and Delagrange from aboutJune 1907 onwards, and was in the subsequent years developed by Farman;and right up to the commencement of the War upheld the principles ofthe box-kite method of construction for training purposes. The chiefmodification of the original design was the addition of flaps (orailerons) at the rear extremities of the main planes to give lateralcontrol, in a manner analogous to the wing-warping method invented bythe Wrights, as a result of which the end curtains between the planeswere abolished. An additional elevator was fitted at the rear of thefixed biplane tail, which eventually led to the discarding of the frontelevator altogether. During the same period the Wright machine came intoline with the others by the fitting of a wheeled undercarriage integralwith the machine. A fixed horizontal tail was also added to the rearrudder, to which a movable elevator was later attached; and, finally, the front elevator was done away with. It will thus be seen that havingstarted from the very different standpoints of automatic stability andcomplete control by the pilot, the Voisin (as developed in the Farman)and Wright machines, through gradual evolution finally resulted inaeroplanes of similar characteristics embodying a modicum of bothfeatures. Before proceeding to the next stage of progress mention should be madeof the experimental work of Captain Ferber in France. This officercarried out a large number of experiments with gliders contemporarilywith the Wrights, adopting--like them--the Chanute biplane principle. Headopted the front elevator from the Wrights, but immediately went a stepfarther by also fitting a fixed tail in rear, which did not become afeature of the Wright machine until some seven or eight years later. Hebuilt and appeared to have flown a machine fitted with a motor in 1905, and was commissioned to go to America by the French War Office on asecret mission to the Wrights. Unfortunately, no complete account of hisexperiments appears to exist, though it can be said that his work was atleast as important as that of any of the other pioneers mentioned. II. MULTIPLICITY OF IDEAS In a review of progress such as this, it is obviously impossible, whena certain stage of development has been reached, owing to the verymultiplicity of experimenters, to continue dealing in anythingapproaching detail with all the different types of machines; and it isproposed, therefore, from this point to deal only with tendencies, andto mention individuals merely as examples of a class of thought ratherthan as personalities, as it is often difficult fairly to allocate theresponsibility for any particular innovation. During 1907 and 1908 a new type of machine, in the monoplane, began toappear from the workshops of Louis Bleriot, Robert Esnault-Pelterie, andothers, which was destined to give rise to long and bitter controversieson the relative advantages of the two types, into which it is notproposed to enter here; though the rumblings of the conflict are stillto be heard by discerning ears. Bleriot's early monoplanes had certainnew features, such as the location of the pilot, and in some cases theengine, below the wing; but in general his monoplanes, particularly thefamous No. XI on which the first Channel crossing was made on July25th, 1909, embodied the main principles of the Wright and Voisintypes, except that the propeller was in front of instead of behind thesupporting surfaces, and was, therefore, what is called a 'tractor' inplace of the then more conventional 'pusher. ' Bleriot aimed at lateralbalance by having the tip of each wing pivoted, though he soon fell intoline with the Wrights and adopted the warping system. The main featuresof the design of Esnault-Pelterie's monoplane was the inverted dihedral(or kathedral as this was called in Mr S. F. Cody's British Army Biplaneof 1907) on the wings, whereby the tips were considerably lower thanthe roots at the body. This was designed to give automatic lateralstability, but, here again, conventional practice was soon adopted andthe R. E. P. Monoplanes, which became well-known in this country throughtheir adoption in the early days by Messrs Vickers, were of the ordinarymonoplane design, consisting of a tractor propeller with wire-stayedwings, the pilot being in an enclosed fuselage containing the engine infront and carrying at its rear extremity fixed horizontal and verticalsurfaces combined with movable elevators and rudder. Constructionally, the R. E. P. Monoplane was of extreme interest as the body was constructedof steel. The Antoinette monoplane, so ably flown by Latham, was anothervery famous machine of the 1909-1910 period, though its performance werefrequently marred by engine failure; which was indeed the bugbear of allthese early experimenters, and it is difficult to say, after this lapseof time, how far in many cases the failures which occurred, both inperformances and even in the actual ability to rise from the ground, were due to defects in design or merely faults in the primitive enginesavailable. The Antoinette aroused admiration chiefly through itsgraceful, birdlike lines, which have probably never been equalled; butits chief interest for our present purpose lies in the novel method ofwing-staying which was employed. Contemporary monoplanes practicallyall had their wings stayed by wires to a post in the centre above thefuselage, and, usually, to the undercarriage below. In the Antoinette, however, a king post was introduced half-way along the wing, from whichwires were carried to the ends of the wings and the body. Thiswas intended to give increased strength and permitted of a greaterwing-spread and consequently improved aspect ratio. The same system ofconstruction was adopted in the British Martinsyde monoplanes of two orthree years later. This period also saw the production of the first triplane, which wasbuilt by A. V. Roe in England and was fitted with a J. A. P. Engine ofonly 9 horse-power--an amazing performance which remains to this dayunequalled. Mr Roe's triplane was chiefly interesting otherwise forthe method of maintaining longitudinal control, which was achievedby pivoting the whole of the three main planes so that their angleof incidence could be altered. This was the direct converse of theuniversal practice of elevating by means of a subsidiary surface eitherin front or rear of the main planes. Recollection of the various flying meetings and exhibitions which oneattended during the years from 1909 to 1911, or even 1912 are chieflynotable for the fact that the first thought on seeing any new type ofmachine was not as to what its 'performance'--in speed, lift, or whatnot--would be; but speculation as to whether it would leave the groundat all when eventually tried. This is perhaps the best indication of theoutstanding characteristic of that interim period between the time ofthe first actual flights and the later period, commencing about 1912, when ideas had become settled and it was at last becoming possible toforecast on the drawing-board the performance of the completed machinein the air. Without going into details, for which there is no spacehere, it is difficult to convey the correct impression of the chaoticstate which existed as to even the elementary principles of aeroplanedesign. All the exhibitions contained large numbers--one had almostwritten a majority--of machines which embodied the most unusual featuresand which never could, and in practice never did, leave the ground. At the same time, there were few who were sufficiently hardy to saycertainly that this or that innovation was wrong; and consequentlydozens of inventors in every country were conducting isolatedexperiments on both good and bad lines. All kinds of devices, mechanicaland otherwise, were claimed as the solution of the problem of stability, and there was even controversy as to whether any measure of stabilitywas not undesirable; one school maintaining that the only safety layin the pilot having the sole say in the attitude of the machine at anygiven moment, and fearing danger from the machine having any mind ofits own, so to speak. There was, as in most controversies, some righton both sides, and when we come to consider the more settled period from1912 to the outbreak of the War in 1914 we shall find how a compromisewas gradually effected. At the same time, however, though it was at the time difficult to pickout, there was very real progress being made, and, though a number of'freak' machines fell out by the wayside, the pioneer designers of thosedays learnt by a process of trial and error the right principles tofollow and gradually succeeded in getting their ideas crystallised. In connection with stability mention must be made of a machine whichwas evolved in the utmost secrecy by Mr J. W. Dunne in a remote partof Scotland under subsidy from the War office. This type, which wasconstructed in both monoplane and biplane form, showed that it wasin fact possible in 1910 and 1911 to design an aeroplane which coulddefinitely be left to fly itself in the air. One of the Dunne machineswas, for example flown from Farnborough to Salisbury Plain without anycontrol other than the rudder being touched; and on another occasion itflew a complete circle with all controls locked automatically assumingthe correct bank for the radius of turn. The peculiar form of wing used, the camber of which varied from the root to the tip, gave rise however, to a certain loss in efficiency, and there was also a difficulty in thepilot assuming adequate control when desired. Other machines designed tobe stable--such as the German Etrich and the British Weiss gliders andHandley-Page monoplanes--were based on the analogy of a wing attachedto a certain seed found in Nature (the 'Zanonia' leaf), on the rightingeffect of back-sloped wings combined with upturned (or 'negative') tips. Generally speaking, however, the machines of the 1909-1912 period reliedfor what automatic stability they had on the principle of the dihedralangle, or flat V, both longitudinally and laterally. Longitudinally thiswas obtained by setting the tail at a slightly smaller angle than themain planes. The question of reducing the resistance by adopting 'stream-line' forms, along which the air could flow uninterruptedly without the formationof eddies, was not at first properly realised, though credit should begiven to Edouard Nieuport, who in 1909 produced a monoplane with avery large body which almost completely enclosed the pilot and made themachine very fast, for those days, with low horse-power. On one of thesemachines C. T. Weyman won the Gordon-Bennett Cup for America in 1911and another put up a fine performance in the same race with only a 30horse-power engine. The subject, was however, early taken up by theBritish Advisory Committee for Aeronautics, which was established bythe Government in 1909, and designers began to realise the importanceof streamline struts and fuselages towards the end of this transitionperiod. These efforts were at first not always successful and showed attimes a lack of understanding of the problems involved, but there wasa very marked improvement during the year 1912. At the Paris Aero Salonheld early in that year there was a notable variety of ideas on thesubject; whereas by the time of the one held in October designs hadconsiderably settled down, more than one exhibitor showing what werecalled 'monocoque' fuselages completely circular in shape and havingvery low resistance, while the same show saw the introduction ofrotating cowls over the propeller bosses, or 'spinners, ' as they came tobe called during the War. A particularly fine example of stream-liningwas to be found in the Deperdussin monoplane on which Vedrines wonback the Gordon-Bennett Aviation Cup from America at a speed of 105. 5m. P. H. --a considerable improvement on the 78 m. P. H. Of the precedingyear, which was by no means accounted for by the mere increase in enginepower from 100 horse-power to 140 horse-power. This machine was thefirst in which the refinement of 'stream-lining' the pilot's head, whichbecame a feature of subsequent racing machines, was introduced. Thisconsisted of a circular padded excresence above the cockpit immediatelybehind the pilot's head, which gradually tapered off into the topsurface of the fuselage. The object was to give the air an uninterruptedflow instead of allowing it to be broken up into eddies behind thehead of the pilot, and it also provided a support against the enormouswind-pressure encountered. This true stream-line form of fuselage owedits introduction to the Paulhan-Tatin 'Torpille' monoplane of the ParisSalon of early 1917. Altogether the end of the year 1912 began to seethe disappearance of 'freak' machines with all sorts of original ideasfor the increase of stability and performance. Designs had by thengradually become to a considerable extent standardised, and it hadbecome unusual to find a machine built which would fail to fly. TheGnome engine held the field owing to its advantages, as the first ofthe rotary type, in lightness and ease of fitting into the nose of afuselage. The majority of machines were tractors (propeller in front)although a preference, which died down subsequently, was still shown forthe monoplane over the biplane. This year also saw a great increasein the number of seaplanes, although the 'flying boat' type had onlyappeared at intervals and the vast majority were of the ordinaryaeroplane type fitted with floats in place of the land undercarriage;which type was at that time commonly called 'hydro-aeroplane. ' The usualhorse power was 50--that of the smallest Gnome engine--although enginesof 100 to 140 horse-power were also fitted occasionally. The averageweight per horse-power varied from 18 to 25 lbs. , while the wing-loadingwas usually in the neighbourhood of 5 to 6 lbs. Per square foot. Theaverage speed ranged from 65-75 miles per hour. III. PROGRESS ON STANDARDISED LINES In the last section an attempt has been made to show how, during whatwas from the design standpoint perhaps the most critical period, ordergradually became evident out of chaos, ill-considered ideas dropped outthrough failure to make good, and, though there was still plenty of roomfor improvement in details, the bulk of the aeroplanes showed a generalsimilarity in form and conception. There was still a great deal to belearnt in finding the best form of wing section, and performances werestill low; but it had become definitely possible to say that flying hademerged from the chrysalis stage and had become a science. The periodwhich now began was one of scientific development and improvement--inperformance, manoeuvrability, and general airworthiness and stability. The British Military Aeroplane Competition held in the summer of 1912had done much to show the requirements in design by giving possiblythe first opportunity for a definite comparison of the performanceof different machines as measured by impartial observers on standardlines--albeit the methods of measuring were crude. These showed that ahigh speed--for those days--of 75 miles an hour or so was attended bydisadvantages in the form of an equally fast low speed, of 50 miles perhour or more, and generally may be said to have given designers an ideawhat to aim for and in what direction improvements were required. Infact, the most noticeable point perhaps of the machines of this time wasthe marked manner in which a machine that was good in one respectwould be found to be wanting in others. It had not yet been possibleto combine several desirable attributes in one machine. The nearestapproach to this was perhaps to be found in the much discussedGovernment B. E. 2 machine, which was produced from the Royal AircraftFactory at Farnborough, in the summer of 1912. Though considerablycriticized from many points of view it was perhaps the nearest approachto a machine of all-round efficiency that had up to that date appeared. The climbing rate, which subsequently proved so important for militarypurposes, was still low, seldom, if ever, exceeding 400 feet per minute;while gliding angles (ratio of descent to forward travel over the groundwith engine stopped) little exceeded 1 in 8. The year 1912 and 1913 saw the subsequently all-conquering tractorbiplane begin to come into its own. This type, which probably originatedin England, and at any rate attained to its greatest excellence prior tothe War from the drawing offices of the Avro Bristol and Sopwith firms, dealt a blow at the monoplane from which the latter never recovered. The two-seater tractor biplane produced by Sopwith and piloted by H. G. Hawker, showed that it was possible to produce a biplane with at leastequal speed to the best monoplanes, whilst having the advantage ofgreater strength and lower landing speeds. The Sopwith machine had a topspeed of over 80 miles an hour while landing as slowly as little morethan 30 miles an hour; and also proved that it was possible to carry 3passengers with fuel for 4 hours' flight with a motive power of only 80horse-power. This increase in efficiency was due to careful attention todetail in every part, improved wing sections, clean fuselage-lines, andsimplified undercarriages. At the same time, in the early part of 1913a tendency manifested itself towards the four-wheeled undercarriage, a pair of smaller wheels being added in front of the main wheels toprevent overturning while running on the ground; and several designs ofoleo-pneumatic and steel-spring undercarriages were produced in placeof the rubber shock-absorber type which had up till then been almostuniversal. These two statements as to undercarriage designs may appear to becontradictory, but in reality they do not conflict as they both showeda greater attention to the importance of good springing, combined witha desire to avoid complication and a mass of struts and wires whichincreased head resistance. The Olympia Aero Show of March, 1913, also produced a machine which, although the type was not destined to prove the best for the purpose forwhich it was designed, was of interest as being the first to be designedspecially for war purposes. This was the Vickers 'Gun-bus, ' a 'pusher'machine, with the propeller revolving behind the main planes between theoutriggers carrying the tail, with a seat right in front for a gunnerwho was provided with a machine gun on a swivelling mount which had afree field of fire in every direction forward. The device which provedthe death-blow for this type of aircraft during the war will be dealtwith in the appropriate place later, but the machine should not gounrecorded. As a result of a number of accidents to monoplanes the Governmentappointed a Committee at the end of 1912 to inquire into the causes ofthese. The report which was presented in March, 1913, exonerated themonoplane by coming to the conclusion that the accidents were not causedby conditions peculiar to monoplanes, but pointed out certaindesiderata in aeroplane design generally which are worth recording. Theyrecommended that the wings of aeroplanes should be so internally bracedas to have sufficient strength in themselves not to collapse if theexternal bracing wires should give way. The practice, more common inmonoplanes than biplanes, of carrying important bracing wires fromthe wings to the undercarriage was condemned owing to the liability ofdamage from frequent landings. They also pointed out the desirability ofduplicating all main wires and their attachments, and of using strandedcable for control wires. Owing to the suspicion that one accident atleast had been caused through the tearing of the fabric away from thewing, it was recommended that fabric should be more securely fastened tothe ribs of the wings, and that devices for preventing the spreading oftears should be considered. In the last connection it is interesting tonote that the French Deperdussin firm produced a fabric wing-coveringwith extra strong threads run at right-angles through the fabric atintervals in order to limit the tearing to a defined area. In spite, however, of the whitewashing of the monoplane by theGovernment Committee just mentioned, considerable stir was occasionedlater in the year by the decision of the War office not to order anymore monoplanes; and from this time forward until the War period theBritish Army was provided exclusively with biplanes. Even prior to thisthe popularity of the monoplane had begun to wane. At the OlympiaAero Show in March, 1913, biplanes for the first time outnumbered the'single-deckers'(as the Germans call monoplanes); which had the effectof reducing the wing-loading. In the case of the biplanes exhibitedthis averaged about 4 1/2 lbs. Per square foot, while in the case ofthe monoplanes in the same exhibition the lowest was 5 1/2 lbs. , andthe highest over 8 1/2 lbs. Per square foot of area. It may here bementioned that it was not until the War period that the importanceof loading per horse-power was recognised as the true criterion ofaeroplane efficiency, far greater interest being displayed in the amountof weight borne per unit area of wing. An idea of the state of development arrived at about this time may begained from the fact that the Commandant of the Military Wing of theRoyal Flying Corps in a lecture before the Royal Aeronautical Societyread in February, 1913, asked for single-seater scout aeroplanes witha speed of 90 miles an hour and a landing speed of 45 miles an hour--aperformance which even two years later would have been considered modestin the extreme. It serves to show that, although higher performanceswere put up by individual machines on occasion, the general developmenthad not yet reached the stage when such performances could be obtainedin machines suitable for military purposes. So far as seaplanes wereconcerned, up to the beginning of 1913 little attempt had been made tostudy the novel problems involved, and the bulk of the machines at theMonaco Meeting in April, 1913, for instance, consisted of land machinesfitted with floats, in many cases of a most primitive nature, withoutother alterations. Most of those which succeeded in leaving the waterdid so through sheer pull of engine power; while practically all wereincapable of getting off except in a fair sea, which enabled the pilotto jump the machine into the air across the trough between two waves. Stability problems had not yet been considered, and in only one or twocases was fin area added at the rear high up, to counterbalance theeffect of the floats low down in front. Both twin and single-floatmachines were used, while the flying boat was only just beginningto come into being from the workshops of Sopwith in Great Britain, Borel-Denhaut in France, and Curtiss in America. In view of theapproaching importance of amphibious seaplanes, mention should be madeof the flying boat (or 'bat boat' as it was called, followingRudyard Kipling) which was built by Sopwith in 1913 with a wheeledlanding-carriage which could be wound up above the bottom surface of theboat so as to be out of the way when alighting on water. During 1913 the (at one time almost universal) practice originated bythe Wright Brothers, of warping the wings for lateral stability, beganto die out and the bulk of aeroplanes began to be fitted with flaps(or 'ailerons') instead. This was a distinct change for the better, ascontinually warping the wings by bending down the extremities of therear spars was bound in time to produce 'fatigue' in that member andlead to breakage; and the practice became completely obsolete during thenext two or three years. The Gordon-Bennett race of September, 1913, was again won by aDeperdussin machine, somewhat similar to that of the previous year, butwith exceedingly small wings, only 107 square feet in area. The shapeof these wings was instructive as showing how what, from the generalutility point of view, may be disadvantageous can, for a specialpurpose, be turned to account. With a span of 21 feet, the chord was5 feet, giving the inefficient 'aspect ratio' of slightly over 4 to1 only. The object of this was to reduce the lift, and therefore theresistance, to as low a point as possible. The total weight was 1, 500lbs. , giving a wing-loading of 14 lbs. Per square foot--a hithertoundreamt-of figure. The result was that the machine took an enormouslylong run before starting; and after touching the ground on landing ranfor nearly a mile before stopping; but she beat all records by attaininga speed of 126 miles per hour. Where this performance is mainlyinteresting is in contrast to the machines of 1920, which with an evenhigher speed capacity would yet be able to land at not more than 40 or50 miles per hour, and would be thoroughly efficient flying machines. The Rheims Aviation Meeting, at which the Gordon-Bennett race was flown, also saw the first appearance of the Morane 'Parasol' monoplane. TheMorane monoplane had been for some time an interesting machine as beingthe only type which had no fixed surface in rear to give automaticstability, the movable elevator being balanced through being hingedabout one-third of the way back from the front edge. This made themachine difficult to fly except in the hands of experts, but it wasvery quick and handy on the controls and therefore useful for racingpurposes. In the 'Parasol' the modification was introduced of raisingthe wing above the body, the pilot looking out beneath it, in order togive as good a view as possible. Before passing to the year 1914 mention should be made of the featperformed by Nesteroff, a Russian, and Pegoud, a French pilot, who werethe first to demonstrate the possibilities of flying upside-down andlooping the loop. Though perhaps not coming strictly within the purviewof a chapter on design (though certain alterations were made to the topwing-bracing of the machine for this purpose) this performance wasof extreme importance to the development of aviation by showing thepossibility of recovering, given reasonable height, from any position inthe air; which led designers to consider the extra stresses to which anaeroplane might be subjected and to take steps to provide for them byincreasing strength where necessary. When the year 1914 opened a speed of 126 miles per hour had beenattained and a height of 19, 600 feet had been reached. The Sopwith andAvro (the forerunner of the famous training machine of the War period)were probably the two leading tractor biplanes of the world, bothtwo-seaters with a speed variation from 40 miles per hour up to some90 miles per hour with 80 horse-power engines. The French were stillpinning their faith mainly to monoplanes, while the Germans werebeginning to come into prominence with both monoplanes and biplanes ofthe 'Taube' type. These had wings swept backward and also upturnedat the wing-tips which, though it gave a certain measure of automaticstability, rendered the machine somewhat clumsy in the air, and theirperformances were not on the whole as high as those of either France orGreat Britain. Early in 1914 it became known that the experimental work of EdwardBusk--who was so lamentably killed during an experimental flight laterin the year--following upon the researches of Bairstow and others hadresulted in the production at the Royal Aircraft Factory at Farnboroughof a truly automatically stable aeroplane. This was the 'R. E. '(Reconnaissance Experimental), a development of the B. E. Which hasalready been referred to. The remarkable feature of this design was thatthere was no particular device to which one could point out as the causeof the stability. The stable result was attained simply by detaileddesign of each part of the aeroplane, with due regard to its relationto, and effect on, other parts in the air. Weights and areas were sonicely arranged that under practically any conditions the machine tendedto right itself. It did not, therefore, claim to be a machine which itwas impossible to upset, but one which if left to itself would tendto right itself from whatever direction a gust might come. When theprinciples were extended to the 'B. E. 2c' type (largely used at theoutbreak of the War) the latter machine, if the engine were switched off at a height of not less than 1, 000 feet above the ground, would aftera few moments assume its correct gliding angle and glide down to theground. The Paris Aero Salon of December, 1913, had been remarkable chiefly forthe large number of machines of which the chassis and bodywork had beenconstructed of steel-tubing; for the excess of monoplanes over biplanes;and (in the latter) predominance of 'pusher' machines (with propellerin rear of the main planes) compared with the growing British preferencefor 'tractors' (with air screw in front). Incidentally, the MauriceFarman, the last relic of the old type box-kite with elevator in frontappeared shorn of this prefix, and became known as the 'short-horn' incontradistinction to its front-elevatored predecessor which, owing toits general reliability and easy flying capabilities, had long beenaffectionately called the 'mechanical cow. ' The 1913 Salon also sawsome lingering attempts at attaining automatic stability by pendulum andother freak devices. Apart from the appearance of 'R. E. 1, ' perhaps the most notabledevelopment towards the end of 1913 was the appearance of the Sopwith'Tabloid 'tractor biplane. This single-seater machine, evolved fromthe two-seater previously referred to, fitted with a Gnome engine of 80horse-power, had the, for those days, remarkable speed of 92 miles anhour; while a still more notable feature was that it could remain inlevel flight at not more than 37 miles per hour. This machine is ofparticular importance because it was the prototype and forerunner of thesuccessive designs of single-seater scout fighting machines which wereused so extensively from 1914 to 1918. It was also probably the firstmachine to be capable of reaching a height of 1, 000 feet within oneminute. It was closely followed by the 'Bristol Bullet, ' which wasexhibited at the Olympia Aero Show of March, 1914. This last pre-warshow was mainly remarkable for the good workmanship displayed--ratherthan for any distinct advance in design. In fact, there was a notablediversity in the types displayed, but in detailed design considerableimprovements were to be seen, such as the general adoption of strandedsteel cable in place of piano wire for the mail bracing. IV. THE WAR PERIOD Up to this point an attempt has been made to give some idea of theprogress that was made during the eleven years that had elapsed sincethe days of the Wrights' first flights. Much advance had been made andaeroplanes had settled down, superficially at any rate, into more orless standardised forms in three main types--tractor monoplanes, tractorbiplanes, and pusher biplanes. Through the application of the resultsof experiments with models in wind tunnels to full-scale machines, considerable improvements had been made in the design of wing sections, which had greatly increased the efficiency of aeroplanes by raising theamount of 'lift' obtained from the wing compared with the 'drag' (orresistance to forward motion) which the same wing would cause. In thesame way the shape of bodies, interplane struts, etc. , had beenimproved to be of better stream-line shape, for the further reductionof resistance; while the problems of stability were beginning to betolerably well understood. Records (for what they are worth) stoodat 21, 000 feet as far as height was concerned, 126 miles per hour forspeed, and 24 hours duration. That there was considerable room fordevelopment is, however, evidenced by a statement made by the late B. C. Hucks (the famous pilot) in the course of an address delivered beforethe Royal Aeronautical Society in July, 1914. 'I consider, ' he said, 'that the present day standard of flying is due far more to theimprovement in piloting than to the improvement in machines.... Iconsider those (early 1914) machines are only slight improvements onthe machines of three years ago, and yet they are put through evolutionswhich, at that time, were not even dreamed of. I can take a good exampleof the way improvement in piloting has outdistanced improvement inmachines--in the case of myself, my 'looping' Bleriot. Most of you knowthat there is very little difference between that machine and the 50horse-power Bleriot of three years ago. ' This statement was, of course, to some extent an exaggeration and was by no means agreed with bydesigners, but there was at the same time a germ of truth in it. Thereis at any rate little doubt that the theory and practice of aeroplanedesign made far greater strides towards becoming an exact science duringthe four years of War than it had done during the six or seven yearspreceding it. It is impossible in the space at disposal to treat of this developmenteven with the meagre amount of detail that has been possible whilecovering the 'settling down' period from 1911 to 1914, and it isproposed, therefore, to indicate the improvements by sketching brieflythe more noticeable difference in various respects between the averagemachine of 1914 and a similar machine of 1918. In the first place, it was soon found that it was possible to obtaingreater efficiency and, in particular, higher speeds, from tractormachines than from pusher machines with the air screw behind the mainplanes. This was for a variety of reasons connected with the efficiencyof propellers and the possibility of reducing resistance to a greaterextent in tractor machines by using a 'stream-line' fuselage (or body)to connect the main planes with the tail. Full advantage of this couldnot be taken, however, owing to the difficulty of fixing a machine-gunin a forward direction owing to the presence of the propeller. This wasfinally overcome by an ingenious device (known as an 'Interrupter gear')which allowed the gun to fire only when none of the propeller bladeswas passing in front of the muzzle. The monoplane gradually fell intodesuetude, mainly owing to the difficulty of making that type adequatelystrong without it becoming prohibitively heavy, and also because of itshigh landing speed and general lack of manoeuvrability. The triplanewas also little used except in one or two instances, and, practicallyspeaking, every machine was of the biplane tractor type. A careful consideration of the salient features leading to maximumefficiency in aeroplanes--particularly in regard to speed and climb, which were the two most important military requirements--showed thata vital feature was the reduction in the amount of weight lifted perhorse-power employed; which in 1914 averaged from 20 to 25 lbs. This waseffected both by gradual increase in the power and size of the enginesused and by great improvement in their detailed design (by increasingcompression ratio and saving weight whenever possible); with the resultthat the motive power of single-seater aeroplanes rose from 80 and 100horse-power in 1914 to an average of 200 to 300 horse-power, while theactual weight of the engine fell from 3 1/2-4 lbs. Per horse-power to anaverage of 2 1/2 lbs. Per horse-power. This meant that while a pre-warengine of 100 horse-power would weigh some 400 lbs. , the 1918 enginedeveloping three times the power would have less than double the weight. The result of this improvement was that a scout aeroplane at the timeof the Armistice would have 1 horse-power for every 8 lbs. Of weightlifted, compared with the 20 or 25 lbs. Of its 1914 predecessors. Thisproduced a considerable increase in the rate of climb, a good postwarmachine being able to reach 10, 000 feet in about 5 minutes and 20, 000feet in under half an hour. The loading per square foot was alsoconsiderably increased; this being rendered possible both by improvementin the design of wing sections and by more scientific constructiongiving increased strength. It will be remembered that in the machineof the very early period each square foot of surface had only to lifta weight of some 1 1/2 to 2 lbs. , which by 1914 had been increased toabout 4 lbs. By 1918 aeroplanes habitually had a loading of 8 lbs. Ormore per square foot of area; which resulted in great increase in speed. Although a speed of 126 miles per hour had been attained by a speciallydesigned racing machine over a short distance in 1914, the average atthat period little exceeded, if at all, 100 miles per hour; whereas in1918 speeds of 130 miles per hour had become a commonplace, and shortlyafterwards a speed of over 166 miles an hour was achieved. In another direction, also, that of size, great developments were made. Before the War a few machines fitted with more than one engine had beenbuilt (the first being a triple Gnome-engined biplane built by MessrsShort Bros. At Eastchurch in 1913), but none of large size had beensuccessfully produced, the total weight probably in no case exceedingabout 2 tons. In 1916, however, the twin engine Handley-Page biplanewas produced, to be followed by others both in this country and abroad, which represented a very great increase in size and, consequently, load-carrying capacity. By the end of the War period several types werein existence weighing a total of 10 tons when fully loaded, of whichsome 4 tons or more represented 'useful load' available for crew, fuel, and bombs or passengers. This was attained through very carefulattention to detailed design, which showed that the material could beemployed more efficiently as size increased, and was also due to thefact that a large machine was not liable to be put through the sameevolutions as a small machine, and therefore could safely be built witha lower factor of safety. Owing to the fact that a wing section which isadopted for carrying heavy loads usually has also a somewhat low liftto drag ratio, and is not therefore productive of high speed, thesemachines are not as fast as light scouts; but, nevertheless, they provedthemselves capable of achieving speeds of 100 miles an hour or more insome cases; which was faster than the average small machine of 1914. In one respect the development during the War may perhaps have provedto be somewhat disappointing, as it might have been expected that greatimprovements would be effected in metal construction, leading almost tothe abolition of wooden structures. Although, however, a good deal ofexperimental work was done which resulted in overcoming at any rate theworst of the difficulties, metal-built machines were little used (exceptto a certain extent in Germany) chiefly on account of the need for rapidproduction and the danger of delay resulting from switching over fromknown and tried methods to experimental types of construction. The Germans constructed some large machines, such as the giantSiemens-Schukhert machine, entirely of metal except for the wingcovering, while the Fokker and Junker firms about the time of theArmistice in 1918 both produced monoplanes with very deep all-metalwings (including the covering) which were entirely unstayed externally, depending for their strength on internal bracing. In Great Britain cablebracing gave place to a great extent to 'stream-line wires, ' which aresteel rods rolled to a more or less oval section, while tie-rods werealso extensively used for the internal bracing of the wings. Greatdevelopments in the economical use of material were also made in thedirection of using built-up main spars for the wings and interplanestruts; spars composed of a series of layers (or 'laminations') ofdifferent pieces of wood also being used. Apart from the metallic construction of aeroplanes an enormous amountof work was done in the testing of different steels and light alloys foruse in engines, and by the end of the War period a number of aircraftengines were in use of which the pistons and other parts were of suchalloys; the chief difficulty having been not so much in the design as inthe successful heat-treatment and casting of the metal. An important development in connection with the inspection andtesting of aircraft parts, particularly in the case of metal, was theexperimental application of X-ray photography, which showed up latentdefects, both in the material and in manufacture, which would otherwisehave passed unnoticed. This method was also used to test the penetrationof glue into the wood on each side of joints, so giving a measure of thestrength; and for the effect of 'doping' the wings, dope being a film(of cellulose acetate dissolved in acetone with other chemicals)applied to the covering of wings and bodies to render the linen taut andweatherproof, besides giving it a smooth surface for the lessening of'skin friction' when passing rapidly through the air. An important result of this experimental work was that it in many casesenabled designers to produce aeroplane parts from less costly materialthan had previously been considered necessary, without impairing thestrength. It may be mentioned that it was found undesirable to usewelded joints on aircraft in any part where the material is subjecttoa tensile or bending load, owing to the danger resulting from badworkmanship causing the material to become brittle--an effect whichcannot be discovered except by cutting through the weld, which, ofcourse, involves a test to destruction. Written, as it has been, inAugust, 1920, it is impossible in this chapter to give any conception ofhow the developments of War will be applied to commercial aeroplanes, as few truly commercial machines have yet been designed, and even thosestill show distinct traces of the survival of war mentality. When, however, the inevitable recasting of ideas arrives, it will becomeevident, whatever the apparent modification in the relative importanceof different aspects of design, that enormous advances were made underthe impetus of War which have left an indelible mark on progress. We have, during the seventeen years since aeroplanes first took the air, seen them grow from tentative experimental structures of unknown andunknowable performance to highly scientific products, of which notonly the performances (in speed, load-carrying capacity, and climb) areknown, but of which the precise strength and degree of stability can beforecast with some accuracy on the drawing board. For the rest, withthe future lies--apart from some revolutionary change in fundamentaldesign--the steady development of a now well-tried and well-foundengineering structure. PART III. AEROSTATICS I. BEGINNINGS Francesco Lana, with his 'aerial ship, ' stands as one of the first greatexponents of aerostatics; up to the time of the Montgolfier andCharles balloon experiments, aerostatic and aerodynamic research are soinextricably intermingled that it has been thought well to treat of themas one, and thus the work of Lana, Veranzio and his parachute, Guzman'sfrauds, and the like, have already been sketched. In connection withGuzman, Hildebrandt states in his Airships Past and Present, afairly exhaustive treatise on the subject up to 1906, the year of itspublication, that there were two inventors--or charlatans--Lorenzo deGuzman and a monk Bartolemeo Laurenzo, the former of whom constructedan unsuccessful airship out of a wooden basket covered with paper, while the latter made certain experiments with a machine of which nodescription remains. A third de Guzman, some twenty-five years later, announced that he had constructed a flying machine, with which heproposed to fly from a tower to prove his success to the public. Thelack of record of any fatal accident overtaking him about that timeseems to show that the experiment was not carried out. Galien, a French monk, published a book L'art de naviguer dans l'airin 1757, in which it was conjectured that the air at high levels waslighter than that immediately over the surface of the earth. Galienproposed to bring down the upper layers of air and with them fill avessel, which by Archimidean principle would rise through the heavieratmosphere. If one went high enough, said Galien, the air would be twothousand times as light as water, and it would be possible to constructan airship, with this light air as lifting factor, which should be aslarge as the town of Avignon, and carry four million passengers withtheir baggage. How this high air was to be obtained is matter forconjecture--Galien seems to have thought in a vicious circle, in whichthe vessel that must rise to obtain the light air must first be filledwith it in order to rise. Cavendish's discovery of hydrogen in 1776 set men thinking, and soon acertain Doctor Black was suggesting that vessels might be filled withhydrogen, in order that they might rise in the air. Black, however, didnot get beyond suggestion; it was Leo Cavallo who first made experimentswith hydrogen, beginning with filling soap bubbles, and passing on tobladders and special paper bags. In these latter the gas escaped, and Cavallo was about to try goldbeaters' skin at the time that theMontgolfiers came into the field with their hot air balloon. Joseph and Stephen Montgolfier, sons of a wealthy French papermanufacturer, carried out many experiments in physics, and Josephinterested himself in the study of aeronautics some time before thefirst balloon was constructed by the brothers--he is said to have madea parachute descent from the roof of his house as early as 1771, butof this there is no proof. Galien's idea, together with study of themovement of clouds, gave Joseph some hope of achieving aerostationthrough Galien's schemes, and the first experiments were made by passingsteam into a receiver, which, of course, tended to rise--but therapid condensation of the steam prevented the receiver from more thanthreatening ascent. The experiments were continued with smoke, whichproduced only a slightly better effect, and, moreover, the paper baginto which the smoke was induced permitted of escape through its pores;finding this method a failure the brothers desisted until Priestley'swork became known to them, and they conceived the use of hydrogen asa lifting factor. Trying this with paper bags, they found that thehydrogen escaped through the pores of the paper. Their first balloon, made of paper, reverted to the hot-air principle;they lighted a fire of wool and wet straw under the balloon--and as amatter of course the balloon took fire after very little experiment;thereupon they constructed a second, having a capacity of 700 cubicfeet, and this rose to a height of over 1, 000 feet. Such a success gavethem confidence, and they gave their first public exhibition on June5th, 1783, with a balloon constructed of paper and of a circumference of112 feet. A fire was lighted under this balloon, which, after rising toa height of 1, 000 feet, descended through the cooling of the air insidea matter of ten minutes. At this the Academie des Sciences invited thebrothers to conduct experiments in Paris. The Montgolfiers were undoubtedly first to send up balloons, but otherexperimenters were not far behind them, and before they could get toParis in response to their invitation, Charles, a prominent physicist ofthose days, had constructed a balloon of silk, which he proofed againstescape of gas with rubber--the Roberts had just succeeded in dissolvingthis substance to permit of making a suitable coating for the silk. Witha quarter of a ton of sulphuric acid, and half a ton of iron filingsand turnings, sufficient hydrogen was generated in four days to fillCharles's balloon, which went up on August 28th, 1783. Although the daywas wet, Paris turned out to the number of over 300, 000 in the Champs deMars, and cannon were fired to announce the ascent of the balloon. This, rising very rapidly, disappeared amid the rain clouds, but, probablybursting through no outlet being provided to compensate for theescape of gas, fell soon in the neighbourhood of Paris. Here peasants, ascribing evil supernatural influence to the fall of such a thing fromnowhere, went at it with the implements of their craft--forks, hoes, andthe like--and maltreated it severely, finally attaching it to a horse'stail and dragging it about until it was mere rag and scrap. Meanwhile, Joseph Montgolfier, having come to Paris, set about theconstruction of a balloon out of linen; this was in three diversesections, the top being a cone 30 feet in depth, the middle a cylinder42 feet in diameter by 26 feet in depth, and the bottom another cone 20feet in depth from junction with the cylindrical portion to its point. The balloon was both lined and covered with paper, decorated in blue andgold. Before ever an ascent could be attempted this ambitious balloonwas caught in a heavy rainstorm which reduced its paper covering to pulpand tore the linen at its seams, so that a supervening strong wind torethe whole thing to shreds. Montgolfier's next balloon was spherical, having a capacity of 52, 000cubic feet. It was made from waterproofed linen, and on September 19th, 1783, it made an ascent for the palace courtyard at Versailles, takingup as passengers a cock, a sheep, and a duck. A rent at the top of theballoon caused it to descend within eight minutes, and the duck andsheep were found none the worse for being the first living things toleave the earth in a balloon, but the cock, evidently suffering, wasthought to have been affected by the rarefaction of the atmosphere atthe tremendous height reached--for at that time the general opinion wasthat the atmosphere did not extend more than four or five miles abovethe earth's surface. It transpired later that the sheep had trampled onthe cock, causing more solid injury than any that might be inflicted byrarefied air in an eight-minute ascent and descent of a balloon. For achieving this flight Joseph Montgolfier received from the Kingof France a pension of of L40, while Stephen was given the order of StMichael, and a patent of nobility was granted to their father. They weremade members of the Legion d'Honneur, and a scientific deputation, of which Faujas de Saint-Fond, who had raised the funds with whichCharles's hydrogen balloon was constructed, presented to StephenMontgolfier a gold medal struck in honour of his aerial conquest. Since Joseph appears to have had quite as much share in the successas Stephen, the presentation of the medal to one brother only was inquestionable taste, unless it was intended to balance Joseph's pension. Once aerostation had been proved possible, many people began theconstruction of small balloons--the wholehole thing was regarded as amatter of spectacles and a form of amusement by the great majority. Acertain Baron de Beaumanoir made the first balloon of goldbeaters' skin, this being eighteen inches in diameter, and using hydrogen as a liftingfactor. Few people saw any possibilities in aerostation, in spite ofthe adventures of the duck and sheep and cock; voyages to the moon weretalked and written, and there was more of levity than seriousness overballooning as a rule. The classic retort of Benjamin Franklin standsas an exception to the general rule: asked what was the use ofballooning--'What's the use of a baby?' he countered, and the spirit ofthat reply brought both the dirigible and the aeroplane to being, later. The next noteworthy balloon was one by Stephen Montgolfier, designed totake up passengers, and therefore of rather large dimensions, as thesethings went then. The capacity was 100, 000 cubic feet, the depth being85 feet, and the exterior was very gaily decorated. A short, cylindricalopening was made at the lower extremity, and under this a fire-pan wassuspended, above the passenger car of the balloon. On October 15th, 1783, Pilatre de Rozier made the first balloon ascent--but the balloonwas held captive, and only allowed to rise to a height of 80 feet. But, a little later in 1783, Rozier secured the honour of making the firstascent in a free balloon, taking up with him the Marquis d'Arlandes. It had been originally intended that two criminals, condemned to death, should risk their lives in the perilous venture, with the prospect ofa free pardon if they made a safe descent, but d'Arlandes got the royalconsent to accompany Rozier, and the criminals lost their chance. Rozierand d'Arlandes made a voyage lasting for twenty-five minutes, and, onlanding, the balloon collapsed with such rapidity as almost to suffocateRozier, who, however, was dragged out to safety by d'Arlandes. Thisfirst aerostatic journey took place on November 21st, 1783. Some seven months later, on June 4th, 1784, a Madame Thible ascended ina free balloon, reaching a height of 9, 000 feet, and making a journeywhich lasted for forty-five minutes--the great King Gustavus of Swedenwitnessed this ascent. France grew used to balloon ascents in the courseof a few months, in spite of the brewing of such a storm as mighthave been calculated to wipe out all but purely political interests. Meanwhile, interest in the new discovery spread across the Channel, and on September 15th, 1784, one Vincent Lunardi made the first balloonvoyage in England, starting from the Artillery Ground at Chelsea, witha cat and dog as passengers, and landing in a field in the parish ofStandon, near Ware. There is a rather rare book which gives a verydetailed account of this first ascent in England, one copy of whichis in the library of the Royal Aeronautical Society; the venturesomeLunardi won a greater measure of fame through his exploit than didCody for his infinitely more courageous and--from a scientific point ofview--valuable first aeroplane ascent in this country. The Montgolfier type of balloon, depending on hot air for its liftingpower, was soon realised as having dangerous limitations. There wasalways a possibility of the balloon catching fire while it was beingfilled, and on landing there was further danger from the hot pan whichkept up the supply of hot air on the voyage--the collapsing balloon fellon the pan, inevitably. The scientist Saussure, observing the filling ofthe balloons very carefully, ascertained that it was rarefaction of theair which was responsible for the lifting power, and not the heat initself, and, owing to the rarefaction of the air at normal temperatureat great heights above the earth, the limit of ascent for a balloon ofthe Montgolfier type was estimated by him at under 9, 000 feet. Moreover, since the amount of fuel that could be carried for maintaining theheat of the balloon after inflation was subject to definite limits, prescribed by the carrying capacity of the balloon, the duration of thejourney was necessarily limited just as strictly. These considerations tended to turn the minds of those interestedin aerostation to consideration of the hydrogen balloon evolved byProfessor Charles. Certain improvements had been made by Charlessince his first construction; he employed rubber-coated silk in theconstruction of a balloon of 30 feet diameter, and provided a net fordistributing the pressure uniformly over the surface of the envelope;this net covered the top half of the balloon, and from its lower edgedependent ropes hung to join on a wooden ring, from which the car ofthe balloon was suspended--apart from the extension of the net so as tocover in the whole of the envelope, the spherical balloon of to-day isvirtually identical with that of Charles in its method of construction. He introduced the valve at the top of the balloon, by which escape ofgas could be controlled, operating his valve by means of ropes whichdepended to the car of the balloon, and he also inserted a tube, ofabout 7 inches diameter, at the bottom of the balloon, not only forpurposes of inflation, but also to provide a means of escape for gas incase of expansion due to atmospheric conditions. Sulphuric acid and iron filings were used by Charles for filling hisballoon, which required three days and three nights for the generationof its 14, 000 cubic feet of hydrogen gas. The inflation was completed onDecember 1st, 1783, and the fittings carried included a barometer and agrapnel form of anchor. In addition to this, Charles provided the first'ballon sonde' in the form of a small pilot balloon which he handed toMontgolfier to launch before his own ascent, in order to determine thedirection and velocity of the wind. It was a graceful compliment to hisrival, and indicated that, although they were both working to the oneend, their rivalry was not a matter of bitterness. Ascending on December 1st, 1783, Charles took with him one of thebrothers Robert, and with him made the record journey up to that date, covering a period of three and three-quarter hours, in which time theyjourneyed some forty miles. Robert then landed, and Charles ascendedagain alone, reaching such a height as to feel the effects of therarefaction of the air, this very largely due to the rapidity of hisascent. Opening the valve at the top of the balloon, he descendedthirty-five minutes after leaving Robert behind, and came to earth a fewmiles from the point of the first descent. His discomfort over the rapidascent was mainly due to the fact that, when Robert landed, he forgot tocompensate for the reduction of weight by taking in further ballast, but the ascent proved the value of the tube at the bottom of the balloonenvelope, for the gas escaped very rapidly in that second ascent, and, but for the tube, the balloon must inevitably have burst in the air, with fatal results for Charles. As in the case of aeroplane flight, as soon as the balloon was provedpracticable the flight across the English Channel was talked of, andRozier, who had the honour of the first flight, announced his intentionof being first to cross. But Blanchard, who had an idea for a 'flyingcar, ' anticipated him, and made a start from Dover on January 7th, 1785, taking with him an American doctor named Jeffries. Blanchard fitted outhis craft for the journey very thoroughly, taking provisions, oars, andeven wings, for propulsion in case of need. He took so much, in fact, that as soon as the balloon lifted clear of the ground the whole of theballast had to be jettisoned, lest the balloon should drop into the sea. Half-way across the Channel the sinking of the balloon warned Blanchardthat he had to part with more than ballast to accomplish the journey, and all the equipment went, together with certain books and papers thatwere on board the car. The balloon looked perilously like collapsing, and both Blanchard and Jeffries began to undress in order further tolighten their craft--Jeffries even proposed a heroic dive to save thesituation, but suddenly the balloon rose sufficiently to clear theFrench coast, and the two voyagers landed at a point near Calais inthe Forest of Gaines, where a marble column was subsequently erected tocommemorate the great feat. Rozier, although not first across, determined to be second, and forthat purpose he constructed a balloon which was to owe its buoyancy toa combination of the hydrogen and hot air principles. There was aspherical hydrogen balloon above, and beneath it a cylindrical containerwhich could be filled with hot air, thus compensating for the leakage ofgas from the hydrogen portion of the balloon--regulating the heat ofhis fire, he thought, would give him perfect control in the matter ofascending and descending. On July 6th, 1785, a favourable breeze gave Rozier his opportunity ofstarting from the French coast, and with a passenger aboard he cast offin his balloon, which he had named the 'Aero-Montgolfiere. ' There was arapid rise at first, and then for a time the balloon remained stationaryover the land, after which a cloud suddenly appeared round the balloon, denoting that an explosion had taken place. Both Rozier and hiscompanion were killed in the fall, so that he, first to leave the earthby balloon, was also first victim to the art of aerostation. There followed, naturally, a lull in the enthusiasm with whichballooning had been taken up, so far as France was concerned. In Italy, however, Count Zambeccari took up hot-air ballooning, using a spiritlamp to give him buoyancy, and on the first occasion when the ballooncar was set on fire Zambeccari let down his passenger by means of theanchor rope, and managed to extinguish the fire while in the air. Thisreduced the buoyancy of the balloon to such an extent that it fellinto the Adriatic and was totally wrecked, Zambeccari being rescued byfishermen. He continued to experiment up to 1812, when he attempted toascend at Bologna; the spirit in his lamp was upset by the collisionof the car with a tree, and the car was again set on fire. Zambeccarijumped from the car when it was over fifty feet above level ground, andwas killed. With him the Rozier type of balloon, combining the hydrogenand hot air principles, disappeared; the combination was obviously toodangerous to be practical. The brothers Robert were first to note how the heat of the sun acted onthe gases within a balloon envelope, and it has since been ascertainedthat sun rays will heat the gas in a balloon to as much as 80 degreesFahrenheit greater temperature than the surrounding atmosphere;hydrogen, being less affected by change of temperature than coal gas, isthe most suitable filling element, and coal gas comes next as the mediumof buoyancy. This for the free and non-navigable balloon, though for theairship, carrying means of combustion, and in military work liable toignition by explosives, the gas helium seems likely to replace hydrogen, being non-combustible. In spite of the development of the dirigible airship, there remainswork for the free, spherical type of balloon in the scientific field. Blanchard's companion on the first Channel crossing by balloon, DrJeffries, was the first balloonist to ascend for purely scientificpurposes; as early as 1784 he made an ascent to a height of 9, 000 feet, and observed a fall in temperature of from degrees--at the level ofLondon, where he began his ascent--to 29 degrees at the maximumheight reached. He took up an electrometer, a hydrometer, a compass, athermometer, and a Toricelli barometer, together with bottles of water, in order to collect samples of the air at different heights. In 1785 hemade a second ascent, when trigonometrical observations of the height ofthe balloon were made from the French coast, giving an altitude of 4, 800feet. The matter was taken up on its scientific side very early in America, experiments in Philadelphia being almost simultaneous with those of theMontgolfiers in France. The flight of Rozier and d'Arlandes inspired twomembers of the Philadelphia Philosophical Academy to construct a balloonor series of balloons of their own design; they made a machine whichconsisted of no less than 47 small hydrogen balloons attached to awicker car, and made certain preliminary trials, using animals aspassengers. This was followed by a captive ascent with a man aspassenger, and eventually by the first free ascent in America, whichwas undertaken by one James Wilcox, a carpenter, on December 28th, 1783. Wilcox, fearful of falling into a river, attempted to regulate hislanding by cutting slits in some of the supporting balloons, which wasthe method adopted for regulating ascent or descent in this machine. He first cut three, and then, finding that the effect produced was notsufficient, cut three more, and then another five--eleven out of theforty-seven. The result was so swift a descent that he dislocated hiswrist on landing. A NOTE ON BALLONETS OR AIR BAGS. Meusnier, toward the end of the eighteenth century, was first toconceive the idea of compensating for the loss of gas due to expansionby fitting to the interior of a free balloon a ballonet, or air bag, which could be pumped full of air so as to retain the shape and rigidityof the envelope. The ballonet became particularly valuable as soon as airshipconstruction became general, and it was in the course of advancein Astra Torres design that the project was introduced of using theballonets in order to give inclination from the horizontal. In theearlier Astra Torres, trimming was accomplished by moving the car foreand aft--this in itself was an advance on the separate 'sliding weigh'principle--and this was the method followed in the Astra Torres boughtby the British Government from France in 1912 for training airshippilots. Subsequently, the two ballonets fitted inside the envelope weremade to serve for trimming by the extent of their inflation, and thismethod of securing inclination proved the best until exterior rudders, and greater engine power, supplanted it, as in the Zeppelin and, infact, all rigid types. In the kite balloon, the ballonet serves the purpose of a rudder, filling itself through the opening being kept pointed toward thewind--there is an ingenious type of air scoop with non-return valvewhich assures perfect inflation. In the S. S. Type of airship, twoballonets are provided, the supply of air being taken from the propellerdraught by a slanting aluminium tube to the underside of the envelope, where it meets a longitudinal fabric hose which connects the twoballonet air inlets. In this hose the non-return air valves, knownas 'crab-pots, ' are fitted, on either side of the junction with theair-scoop. Two automatic air valves, one for each ballonet, are fittedin the underside of the envelope, and, as the air pressure tends toopen these instead of keeping them shut, the spring of the valve is setinside the envelope. Each spring is set to open at a pressure of 25 to28 mm. II. THE FIRST DIRIGIBLES Having got off the earth, the very early balloonists set about the taskof finding a means of navigating the air but, lacking steam or otheraccessory power to human muscle, they failed to solve the problem. Joseph Montgolfier speedily exploded the idea of propelling a ballooneither by means of oars or sails, pointing out that even in a deadcalm a speed of five miles an hour would be the limit achieved. Still, sailing balloons were constructed, even up to the time of Andree, theexplorer, who proposed to retard the speed of the balloon by ropesdragging on the ground, and then to spread a sail which should catchthe wind and permit of deviation of the course. It has been proved thatslight divergences from the course of the wind can be obtained by thismeans, but no real navigation of the air could be thus accomplished. Professor Wellner, of Brunn, brought up the idea of a sailing balloonin more practical fashion in 1883. He observed that surfaces inclined tothe horizontal have a slight lateral motion in rising and falling, anddeduced that by alternate lowering and raising of such surfaces he wouldbe able to navigate the air, regulating ascent and descent by increasingor decreasing the temperature of his buoyant medium in the balloon. Hecalculated that a balloon, 50 feet in diameter and 150 feet in length, with a vertical surface in front and a horizontal surface behind, mightbe navigated at a speed of ten miles per hour, and in actual tests atBrunn he proved that a single rise and fall moved the balloon threemiles against the wind. His ideas were further developed by Lebaudy inthe construction of the early French dirigibles. According to Hildebrandt, [*] the first sailing balloon was built in 1784by Guyot, who made his balloon egg-shaped, with the smaller end at theback and the longer axis horizontal; oars were intended to propel thecraft, and naturally it was a failure. Carra proposed the use of paddlewheels, a step in the right direction, by mounting them on the sidesof the car, but the improvement was only slight. Guyton de Morveau, entrusted by the Academy of Dijon with the building of a sailingballoon, first used a vertical rudder at the rear end of hisconstruction--it survives in the modern dirigible. His constructionincluded sails and oars, but, lacking steam or other than humanpropulsive power, the airship was a failure equally with Guyot's. [*] Airships Past and Present. Two priests, Miollan and Janinet, proposed to drive balloons through theair by the forcible expulsion of the hot air in the envelope from therear of the balloon. An opening was made about half-way up the envelope, through which the hot air was to escape, buoyancy being maintained by apan of combustibles in the car. Unfortunately, this development of theMontgolfier type never got a trial, for those who were to be spectatorsof the first flight grew exasperated at successive delays, and in theend, thinking that the balloon would never rise, they destroyed it. Meusnier, a French general, first conceived the idea of compensatingfor loss of gas by carrying an air bag inside the balloon, in orderto maintain the full expansion of the envelope. The brothers Robertconstructed the first balloon in which this was tried and placed theair bag near the neck of the balloon which was intended to be drivenby oars, and steered by a rudder. A violent swirl of wind which wasencountered on the first ascent tore away the oars and rudder and brokethe ropes which held the air bag in position; the bag fell into theopening of the neck and stopped it up, preventing the escape of gasunder expansion. The Duc de Chartres, who was aboard, realised theextreme danger of the envelope bursting as the balloon ascended, and at16, 000 feet he thrust a staff through the envelope--another account saysthat he slit it with his sword--and thus prevented disaster. The descentafter this rip in the fabric was swift, but the passengers got offwithout injury in the landing. Meusnier, experimenting in various ways, experimented with regard tothe resistance offered by various shapes to the air, and found that anelliptical shape was best; he proposed to make the car boat--shaped, inorder further to decrease the resistance, and he advocated an entirelyrigid connection between the car and the body of the balloon, asindispensable to a dirigible. [*] He suggested using three propellers, which were to be driven by hand by means of pulleys, and calculated thata crew of eighty would be required to furnish sufficient motive power. Horizontal fins were to be used to assure stability, and Meusnierthoroughly investigated the pressures exerted by gases, in order toascertain the stresses to which the envelope would be subjected. Moreimportant still, he went into detail with regard to the use of air bags, in order to retain the shape of the balloon under varying pressures ofgas due to expansion and consequent losses; he proposed two separateenvelopes, the inner one containing gas, and the space between it andthe outer one being filled with air. Further, by compressing the airinside the air bag, the rate of ascent or descent could be regulated. Lebaudy, acting on this principle, found it possible to pump air at therate of 35 cubic feet per second, thus making good loss of ballast whichhad to be thrown overboard. [*] Hildebrandt. Meusnier's balloon, of course, was never constructed, but his ideas havebeen of value to aerostation up to the present time. His career endedin the revolutionary army in 1793, when he was killed in the fightingbefore Mayence, and the King of Prussia ordered all firing to ceaseuntil Meusnier had been buried. No other genius came forward to carryon his work, and it was realised that human muscle could not drive aballoon with certainty through the air; experiment in this directionwas abandoned for nearly sixty years, until in 1852 Giffard brought thefirst practicable power-driven dirigible to being. Giffard, inventor of the steam injector, had already made balloonascents when he turned to aeronautical propulsion, and constructed asteam engine of 5 horsepower with a weight of only 100 lbs. --a greatachievement for his day. Having got his engine, he set about making theballoon which it was to drive; this he built with the aid of two otherenthusiasts, diverging from Meusnier's ideas by making the ends pointed, and keeping the body narrowed from Meusnier's ellipse to a shape moreresembling a rather fat cigar. The length was 144 feet, and the greatestdiameter only 40 feet, while the capacity was 88, 000 cubic feet. A netwhich covered the envelope of the balloon supported a spar, 66 feet inlength, at the end of which a triangular sail was placed vertically toact as rudder. The car, slung 20 feet below the spar, carried the engineand propeller. Engine and boiler together weighed 350 lbs. , and drovethe 11 foot propeller at 110 revolutions per minute. As precaution against explosion, Giffard arranged wire gauze in frontof the stoke-hole of his boiler, and provided an exhaust pipe whichdischarged the waste gases from the engine in a downward direction. Withthis first dirigible he attained to a speed of between 6 and 8 feet persecond, thus proving that the propulsion of a balloon was a possibility, now that steam had come to supplement human effort. Three years later he built a second dirigible, reducing the diameter andincreasing the length of the gas envelope, with a view to reducing airresistance. The length of this was 230 feet, the diameter only 33 feet, and the capacity was 113, 000 cubic feet, while the upper part of theenvelope, to which the covering net was attached, was specially coveredto ensure a stiffening effect. The car of this dirigible was droppedrather lower than that of the first machine, in order to provide morethoroughly against the danger of explosions. Giffard, with a companionnamed Yon as passenger, took a trial trip on this vessel, and made ajourney against the wind, though slowly. In commencing to descend, thenose of the envelope tilted upwards, and the weight of the car andits contents caused the net to slip, so that just before the dirigiblereached the ground, the envelope burst. Both Giffard and his companionescaped with very slight injuries. Plans were immediately made for the construction of a third dirigible, which was to be 1, 970 feet in length, 98 feet in extreme diameter, andto have a capacity of 7, 800, 000 cubic feet of gas. The engine of thisgiant was to have weighed 30 tons, and with it Giffard expected toattain a speed of 40 miles per hour. Cost prevented the scheme beingcarried out, and Giffard went on designing small steam engines until hisinvention of the steam injector gave him the funds to turn to dirigiblesagain. He built a captive balloon for the great exhibition in Londonin 1868, at a cost of nearly L30, 000, and designed a dirigible balloonwhich was to have held a million and three quarters cubic feet of gas, carry two boilers, and cost about L40, 000. The plans were thoroughlyworked out, down to the last detail, but the dirigible was neverconstructed. Giffard went blind, and died in 1882--he stands as thegreat pioneer of dirigible construction, more on the strength of thetwo vessels which he actually built than on that of the ambitious laterconceptions of his brain. In 1872 Dupuy de Lome, commissioned by the French government, built adirigible which he proposed to drive by man-power--it was anticipatedthat the vessel would be of use in the siege of Paris, but it was notactually tested till after the conclusion of the war. The length ofthis vessel was 118 feet, its greatest diameter 49 feet, the ends beingpointed, and the motive power was by a propeller which was revolved bythe efforts of eight men. The vessel attained to about the same speed asGiffard's steam-driven airship; it was capable of carrying fourteenmen, who, apart from these engaged in driving the propeller, had tomanipulate the pumps which controlled the air bags inside the gasenvelope. In the same year Paul Haenlein, working in Vienna, produced an airshipwhich was a direct forerunner of the Lebaudy type, 164 feet in length, 30 feet greatest diameter, and with a cubic capacity of 85, 000 feet. Semi-rigidity was attained by placing the car as close to the envelopeas possible, suspending it by crossed ropes, and the motive power wasa gas engine of the Lenoir type, having four horizontal cylinders, andgiving about 5 horse-power with a consumption of about 250 cubic feetof gas per hour. This gas was sucked from the envelope of the balloon, which was kept fully inflated by pumping in compensating air to the airbags inside the main envelope. A propeller, 15 feet in diameter, wasdriven by the Lenoir engine at 40 revolutions per minute. This was thefirst instance of the use of an internal combustion engine in connectionwith aeronautical experiments. The envelope of this dirigible was rendered airtight by means ofinternal rubber coating, with a thinner film on the outside. Coal gas, used for inflation, formed a suitable fuel for the engine, but limitedthe height to which the dirigible could ascend. Such trials as were madewere carried out with the dirigible held captive, and a speed of I 5feet per second was attained. Full experiment was prevented throughfunds running low, but Haenlein's work constituted a distinct advance onall that had been done previously. Two brothers, Albert and Gaston Tissandier, were next to enter the fieldof dirigible construction; they had experimented with balloons duringthe Franc-Prussian War, and had attempted to get into Paris by balloonduring the siege, but it was not until 1882 that they produced theirdirigible. This was 92 feet in length and 32 feet in greatest diameter, witha cubic capacity of 37, 500 feet, and the fabric used was varnishedcambric. The car was made of bamboo rods, and in addition to its crewof three, it carried a Siemens dynamo, with 24 bichromate cells, eachof which weighed 17 lbs. The motor gave out 1 1/2 horse-power, which wassufficient to drive the vessel at a speed of up to 10 feet per second. This was not so good as Haenlein's previous attempt and, after L2, 000had been spent, the Tissandier abandoned their experiments, since a5-mile breeze was sufficient to nullify the power of the motor. Renard, a French officer who had studied the problem of dirigibleconstruction since 1878, associated himself first with a brother officernamed La Haye, and subsequently with another officer, Krebs, in theconstruction of the second dirigible to be electrically-propelled. LaHaye first approached Colonel Laussedat, in charge of the Engineers ofthe French Army, with a view to obtaining funds, but was refused, inconsequence of the practical failure of all experiments since 1870. Renard, with whom Krebs had now associated himself, thereupon went toGambetta, and succeeded in getting a promise of a grant of L8, 000 forthe work; with this promise Renard and Krebs set to work. They built their airship in torpedo shape, 165 feet in length, and ofjust over 27 feet greatest diameter--the greatest diameter was at thefront, and the cubic capacity was 66, 000 feet. The car itself was 108feet in length, and 4 1/2 feet broad, covered with silk over the bambooframework. The 23 foot diameter propeller was of wood, and was drivenby an electric motor connected to an accumulator, and yielding 8. 5horsepower. The sweep of the propeller, which might have brought it incontact with the ground in landing, was counteracted by rendering itpossible to raise the axis on which the blades were mounted, and a guiderope was used to obviate damage altogether, in case of rapid descent. There was also a 'sliding weight' which was movable to any requiredposition to shift the centre of gravity as desired. Altogether, withpassengers and ballast aboard, the craft weighed two tons. In the afternoon of August 8th, 1884, Renard and Krebs ascended inthe dirigible--which they had named 'La France, ' from the militaryballooning ground at Chalais-Meudon, making a circular flight of aboutfive miles, the latter part of which was in the face of a slightwind. They found that the vessel answered well to her rudder, andthe five-mile flight was made successfully in a period of 23 minutes. Subsequent experimental flights determined that the air speed of thedirigible was no less than 14 1/2 miles per hour, by far the best thathad so far been accomplished in dirigible flight. Seven flights in allwere made, and of these five were completely successful, the dirigiblereturning to its starting point with no difficulty. On the other twoflights it had to be towed back. Renard attempted to repeat his construction on a larger scale, but fundswould not permit, and the type was abandoned; the motive power was notsufficient to permit of more than short flights, and even to the presenttime electric motors, with their necessary accumulators, are far toocumbrous to compete with the self-contained internal combustion engine. France had to wait for the Lebaudy brothers, just as Germany had to waitfor Zeppelin and Parseval. Two German experimenters, Baumgarten and Wolfert, fitted a Daimler motorto a dirigible balloon which made its first ascent at Leipzig in 1880. This vessel had three cars, and placing a passenger in one of the outercars[*] distributed the load unevenly, so that the whole vessel tiltedover and crashed to the earth, the occupants luckily escaping withoutinjury. After Baumgarten's death, Wolfert determined to carry on withhis experiments, and, having achieved a certain measure of success, heannounced an ascent to take place on the Tempelhofer Field, near Berlin, on June 12th, 1897. The vessel, travelling with the wind, reached aheight of 600 feet, when the exhaust of the motor communicated flame tothe envelope of the balloon, and Wolfert, together with a passenger hecarried, was either killed by the fall or burnt to death on the ground. Giffard had taken special precautions to avoid an accident of thisnature, and Wolfert, failing to observe equal care, paid the fullpenalty. [*] Hildebrandt. Platz, a German soldier, attempting an ascent on the Tempelhofer Fieldin the Schwartz airship in 1897, merely proved the dirigible a failure. The vessel was of aluminium, 0. 008 inch in thickness, strengthened by analuminium lattice work; the motor was two-cylindered petrol-driven; atthe first trial the metal developed such leaks that the vessel cameto the ground within four miles of its starting point. Platz, who wasaboard alone as crew, succeeded in escaping by jumping clear before thecar touched earth, but the shock of alighting broke up the balloon, anda following high wind completed the work of full destruction. A secondaccount says that Platz, finding the propellers insufficient to drivethe vessel against the wind, opened the valve and descended too rapidly. The envelope of this dirigible was 156 feet in length, and the methodof filling was that of pushing in bags, fill them with gas, and thenpulling them to pieces and tearing them out of the body of the balloon. A second contemplated method of filling was by placing a linen envelopeinside the aluminium casing, blowing it out with air, and then admittingthe gas between the linen and the aluminium outer casing. This wouldcompress the air out of the linen envelope, which was to be withdrawnwhen the aluminium casing had been completely filled with gas. All this, however, assumes that the Schwartz type--the first rigiddirigible, by the way--would prove successful. As it proved a failure onthe first trial, the problem of filling it did not arise again. By this time Zeppelin, retired from the German army, had begun todevote himself to the study of dirigible construction, and, a yearafter Schwartz had made his experiment and had failed, he got togethersufficient funds for the formation of a limitedliability company, andstarted on the construction of the first of his series of airships. Theage of tentative experiment was over, and, forerunner of the success ofthe heavier-than-air type of flying machine, successful dirigible flightwas accomplished by Zeppelin in Germany, and by Santos-Dumont in France. III. SANTOS-DUMONT A Brazilian by birth, Santos-Dumont began in Paris in the year 1898 tomake history, which he subsequently wrote. His book, My Airships, is arecord of his eight years of work on lighter-than-air machines, aperiod in which he constructed no less than fourteen dirigible balloons, beginning with a cubic capacity of 6, 350 feet, and an engine of 3horse-power, and rising to a cubic capacity of 71, 000 feet on the tenthdirigible he constructed, and an engine of 60 horse-power, which wasfitted to the seventh machine in order of construction, the one which hebuilt after winning the Deutsch Prize. The student of dirigible construction is recommended to Santos-Dumont'sown book not only as a full record of his work, but also as one of thebest stories of aerial navigation that has ever been written. Throughoutall his experiments, he adhered to the non-rigid type; his firstdirigible made its first flight on September 18th, 1898, starting fromthe Jardin d'Acclimatation to the west of Paris; he calculated that his3 horse-power engine would yield sufficient power to enable him to steerclear of the trees with which the starting-point was surrounded, but, yielding to the advice of professional aeronauts who were present, with regard to the placing of the dirigible for his start, he tore theenvelope against the trees. Two days later, having repaired the balloon, he made an ascent of 1, 300 feet. In descending, the hydrogen left inthe balloon contracted, and Santos-Dumont narrowly escaped a seriousaccident in coming to the ground. His second machine, built in the early spring of 1899, held over 7, 000cubic feet of gas and gave a further 44 lbs. Of ascensional force. Theballoon envelope was very long and very narrow; the first attempt atflight was made in wind and rain, and the weather caused sufficientcontraction of the hydrogen for a wind gust to double the machine up andtoss it into the trees near its starting-point. The inventor immediatelyset about the construction of 'Santos-Dumont No. 3, ' on which he made anumber of successful flights, beginning on November 13th, 1899. Onthe last of his flights, he lost the rudder of the machine and made afortunate landing at Ivry. He did not repair the balloon, consideringit too clumsy in form and its motor too small. Consequently No. 4 wasconstructed, being finished on the 1st, August, 1900. It had a cubiccapacity of 14, 800 feet, a length of 129 feet and greatest diameterof 16. 7 feet, the power plant being a 7 horse-power Buchet motor. Santos-Dumont sat on a bicycle saddle fixed to the long bar suspendedunder the machine, which also supported motor propeller, ballast; andfuel. The experiment of placing the propeller at the stem instead of atthe stern was tried, and the motor gave it a speed of 100 revolutionsper minute. Professor Langley witnessed the trials of the machine, whichproved before the members of the International Congress of Aeronautics, on September 19th, that it was capable of holding its own against astrong wind. Finding that the cords with which his dirigible balloon cars weresuspended offered almost as much resistance to the air as did theballoon itself, Santos-Dumont substituted piano wire and found that thealteration constituted greater progress than many a more showy device. He altered the shape and size of his No. 4 to a certain extent andfitted a motor of 12 horse-power. Gravity was controlled by shiftingweights worked by a cord; rudder and propeller were both placed at thestern. In Santos-Dumont's book there is a certain amount of confusionbetween the No. 4 and No. 5 airships, until he explains that 'No. 5'is the reconstructed 'No. 4. ' It was with No. 5 that he won theEncouragement Prize presented by the Scientific Commission of the ParisAero Club. This he devoted to the first aeronaut who between May andOctober of 1900 should start from St Cloud, round the Eiffel Tower, and return. If not won in that year, the prize was to remain open thefollowing year from May 1st to October 1st, and so on annually untilwon. This was a simplification of the conditions of the Deutsch Prizeitself, the winning of which involved a journey of 11 kilometres in 30minutes. The Santos-Dumont No. 5, which was in reality the modified No. 4 withnew keel, motor, and propeller, did the course of the Deutsch Prize, but with it Santos-Dumont made no attempt to win the prize until July of1901, when he completed the course in 40 minutes, but tore his balloonin landing. On the 8th August, with his balloon leaking, he madea second attempt, and narrowly escaped disaster, the airship beingentirely wrecked. Thereupon he built No. 6 with a cubic capacity of22, 239 feet and a lifting power of 1, 518 lbs. With this machine he won the Deutsch Prize on October 19th, 1901, starting with the disadvantage of a side wind of 20 feet per second. Hereached the Eiffel Tower in 9 minutes and, through miscalculating histurn, only just missed colliding with it. He got No. 6 under controlagain and succeeded in getting back to his starting-point in 29 1/2minutes, thus winning the 125, 000 francs which constituted the DeutschPrize, together with a similar sum granted to him by the BrazilianGovernment for the exploit. The greater part of this money was given bySantos-Dumont to charities. He went on building after this until he had made fourteen non-rigiddirigibles; of these No. 12 was placed at the disposal of the militaryauthorities, while the rest, except for one that was sold to an Americanand made only one trip, were matters of experiment for their maker. Hisconclusions from his experiments may be gathered from his own work:-- 'On Friday, 31st July, 1903, Commandant Hirschauer andLieutenant-Colonel Bourdeaux spent the afternoon with me at my airshipstation at Neuilly St James, where I had my three newest airships--theracing 'No. 7, ' the omnibus 'No. 10, ' and the runabout 'No. 9'--readyfor their study. Briefly, I may say that the opinions expressed by therepresentatives of the Minister of War were so unreservedly favourablethat a practical test of a novel character was decided to be made. Should the airship chosen pass successfully through it the result willbe conclusive of its military value. 'Now that these particular experiments are leaving my exclusivelyprivate control I will say no more of them than what has been alreadypublished in the French press. The test will probably consist of anattempt to enter one of the French frontier towns, such as Belfort orNancy, on the same day that the airship leaves Paris. It will not, of course, be necessary to make the whole journey in the airship. Amilitary railway wagon may be assigned to carry it, with its balloonuninflated, with tubes of hydrogen to fill it, and with all thenecessary machinery and instruments arranged beside it. At some stationa short distance from the town to be entered the wagon may be uncoupledfrom the train, and a sufficient number of soldiers accompanying theofficers will unload the airship and its appliances, transport the wholeto the nearest open space, and at once begin inflating the balloon. Within two hours from quitting the train the airship may be ready forits flight to the interior of the technically-besieged town. 'Such may be the outline of the task--a task presented imperiously toFrench balloonists by the events of 1870-1, and which all the devotionand science of the Tissandier brothers failed to accomplish. To-daythe problem may be set with better hope of success. All the essentialdifficulties may be revived by the marking out of a hostile zone aroundthe town that must be entered; from beyond the outer edge of this zone, then, the airship will rise and take its flight--across it. 'Will the airship be able to rise out of rifle range? I have alwaysbeen the first to insist that the normal place of the airship is in lowaltitudes, and I shall have written this book to little purpose ifI have not shown the reader the real dangers attending any brusquevertical mounting to considerable heights. For this we have the terribleSevero accident before our eyes. In particular, I have expressedastonishment at hearing of experimenters rising to these altitudeswithout adequate purpose in their early stages of experience withdirigible balloons. All this is very different, however, from areasoned, cautious mounting, whose necessity has been foreseen andprepared for. ' Probably owing to the fact that his engines were not of sufficientpower, Santos-Dumont cannot be said to have solved the problem of themilitary airship, although the French Government bought one of hisvessels. At the same time, he accomplished much in furthering andinciting experiment with dirigible airships, and he will always rankhigh among the pioneers of aerostation. His experiments might havegone further had not the Wright brothers' success in America and Frenchinterest in the problem of the heavier-than-air machine turned him fromthe study of dirigibles to that of the aeroplane, in which also he takeshigh rank among the pioneers, leaving the construction of a successfulmilitary dirigible to such men as the Lebaudy brothers, Major Parseval, and Zeppelin. IV. THE MILITARY DIRIGIBLE Although French and German experiment in connection with the productionof an airship which should be suitable for military purposes proceededside by side, it is necessary to outline the development in the twocountries separately, owing to the differing character of the workcarried out. So far as France is concerned, experiment began with theLebaudy brothers, originally sugar refiners, who turned their energiesto airship construction in 1899. Three years of work went to theproduction of their first vessel, which was launched in 1902, havingbeen constructed by them together with a balloon manufacturer namedSurcouf and an engineer, Julliot. The Lebaudy airships were what isknown as semi-rigids, having a spar which ran practically the fulllength of the gas bag to which it was attached in such a way as todistribute the load evenly. The car was suspended from the spar, atthe rear end of which both horizontal and vertical rudders were fixed, whilst stabilising fins were provided at the stern of the gas envelopeitself. The first of the Lebaudy vessels was named the 'Jaune'; itslength was 183 feet and its maximum diameter 30 feet, while the cubiccapacity was 80, 000 feet. The power unit was a 40 horse-power Daimlermotor, driving two propellers and giving a maximum speed of 26 milesper hour. This vessel made 29 trips, the last of which took place inNovember, 1902, when the airship was wrecked through collision with atree. The second airship of Lebaudy construction was 7 feet longer than thefirst, and had a capacity of 94, 000 cubic feet of gas with a triple airbag of 17, 500 cubic feet to compensate for loss of gas; this latter waskept inflated by a rotary fan. The vessel was eventually taken over bythe French Government and may be counted the first dirigible airshipconsidered fit on its tests for military service. Later vessels of the Lebaudy type were the 'Patrie' and 'Republique, 'in which both size and method of construction surpassed those of thetwo first attempts. The 'Patrie' was fitted with a 60 horse-power enginewhich gave a speed of 28 miles an hour, while the vessel had a radius of280 miles, carrying a crew of nine. In the winter of 1907 the 'Patrie'was anchored at Verdun, and encountered a gale which broke her holdon her mooring-ropes. She drifted derelict westward across France, theChannel, and the British Isles, and was lost in the Atlantic. The 'Republique' had an 80 horse-power motor, which, however, only gaveher the same speed as the 'Patrie. ' She was launched in July, 1908, and within three months came to an end which constituted a tragedyfor France. A propeller burst while the vessel was in the air, and oneblade, flying toward the envelope, tore in it a great gash; the airshipcrashed to earth, and the two officers and two non-commissioned officerswho were in the car were instantaneously killed. The Clement Bayard, and subsequently the Astra-Torres, non-rigids, followed on the early Lebaudys and carried French dirigible constructionup to 1912. The Clement Bayard was a simple non-rigid having four lobesat the stern end to assist stability. These were found to retardthe speed of the airship, which in the second and more successfulconstruction was driven by a Clement Bayard motor of 100 horse-power ata speed of 30 miles an hour. On August 23rd, 1909, while being tried foracceptance by the military authorities, this vessel achieved a recordby flying at a height of 5, 000 feet for two hours. The Astra-Torresnon-rigids were designed by a Spaniard, Senor Torres, and built by theAstra Company. The envelope was of trefoil shape, this being due to theinterior rigging from the suspension band; the exterior appearanceis that of two lobes side by side, overlaid by a third. The interiorrigging, which was adopted with a view to decreasing air resistance, supports a low-hung car from the centre of the envelope; steering isaccomplished by means of horizontal planes fixed on the envelope at thestern, and vertical planes depending beneath the envelope, also at thestern end. One of the most successful of French pre-war dirigibles was a ClementBayard built in 1912. In this twin propellers were placed at the frontand horizontal and vertical rudders in a sort of box formation under theenvelope at the stern. The envelope was stream-lined, while the car ofthe machine was placed well forward with horizontal controlling planesabove it and immediately behind the propellers. This airship, whichwas named 'Dupuy de Lome, ' may be ranked as about the most successfulnon-rigid dirigible constructed prior to the War. Experiments with non-rigids in Germany was mainly carried on by MajorParseval, who produced his first vessel in 1906. The main feature ofthis airship consisted in variation in length of the suspension cablesat the will of the operator, so that the envelope could be given anupward tilt while the car remained horizontal in order to give thevessel greater efficiency in climbing. In this machine, the propellerwas placed above and forward of the car, and the controlling planes werefixed directly to the envelope near the forward end. A second vesseldiffered from the first mainly in the matter of its larger size, variable suspension being again employed, together with a similarmethod of control. The vessel was moderately successful, and under MajorParseval's direction a third was constructed for passenger carrying, with two engines of 120 horsepower, each driving propellers of 13 feetdiameter. This was the most successful of the early German dirigibles;it made a number of voyages with a dozen passengers in addition to itscrew, as well as proving its value for military purposes by use asa scout machine in manoeuvres. Later Parsevals were constructedof stream-line form, about 300 feet in length, and with enginessufficiently powerful to give them speeds up to 50 miles an hour. Major Von Gross, commander of a Balloon Battalion, produced semi-rigiddirigibles from 1907 onward. The second of these, driven by two 75horse-power Daimler motors, was capable of a speed of 27 miles an hour;in September of 1908 she made a trip from and back to Berlin whichlasted 13 hours, in which period she covered 176 miles with fourpassengers and reached a height of 4, 000 feet. Her successor, launchedin April of 1909, carried a wireless installation, and the next to this, driven by four motors of 75 horse-power each, reached a speed of 45miles an hour. As this vessel was constructed for military purposes, very few details either of its speed or method of construction were madepublic. Practically all these vessels were discounted by the work of Ferdinandvon Zeppelin, who set out from the first with the idea of constructinga rigid dirigible. Beginning in 1898, he built a balloon on an aluminiumframework covered with linen and silk, and divided into interiorcompartments holding linen bags which were capable of containing nearly400, 000 cubic feet of hydrogen. The total length of this first Zeppelinairship was 420 feet and the diameter 38 feet. Two cars were rigidlyattached to the envelope, each carrying a 16 horse-power motor, drivingpropellers which were rigidly connected to the aluminium framework ofthe balloon. Vertical and horizontal screws were used for lifting andforward driving and a sliding weight was used to raise or lower the stemof the vessel out of the horizontal in order to rise or descend withoutaltering the load by loss of ballast or the lift by loss of gas. The first trial of this vessel was made in July of 1900, and wassingularly unfortunate. The winch by which the sliding weight wasoperated broke, and the balloon was so bent that the working of thepropellers was interfered with, as was the steering. A speed of 13 feetper second was attained, but on descending, the airship ran againstsome piles and was further damaged. Repairs were completed by the endof September, 1900, and on a second trial flight made on October 21st aspeed of 30 feet per second was reached. Zeppelin was far from satisfied with the performance of this vessel, and he therefore set about collecting funds for the construction ofa second, which was completed in 1905. By this time the internalcombustion engine had been greatly improved, and without any increase ofweight, Zeppelin was able to instal two motors of 85 horse-power each. The total capacity was 367, 000 cubic feet of hydrogen, carried in 16 gasbags inside the framework, and the weight of the whole constructionwas 9 tons--a ton less than that of the first Zeppelin airship. Threevertical planes at front and rear controlled horizontal steering, whilerise and fall was controlled by horizontal planes arranged in box form. Accident attended the first trial of this second airship, which tookplace over the Bodensee on November 30th, 1905, 'It had been intended totow the raft, to which it was anchored, further from the shore againstthe wind. But the water was too low to allow the use of the raft. Theballoon was therefore mounted on pontoons, pulled out into the lake, andtaken in tow by a motor-boat. It was caught by a strong wind which wasblowing from the shore, and driven ahead at such a rate that itovertook the motor-boat. The tow rope was therefore at once cut, but itunexpectedly formed into knots and became entangled with the airship, pulling the front end down into the water. The balloon was then caughtby the wind and lifted into the air, when the propellers were setin motion. The front end was at this instant pointing in a downwarddirection, and consequently it shot into the water, where it was foundnecessary to open the valves. '[*] [*] Hildebrandt, Airships Past and Present. The damage done was repaired within six weeks, and the second trialwas made on January 17th, 1906. The lifting force was too great forthe weight, and the dirigible jumped immediately to 1, 500 feet. Thepropellers were started, and the dirigible brought to a lower level, when it was found possible to drive against the wind. The steeringarrangements were found too sensitive, and the motors were stopped, whenthe vessel was carried by the wind until it was over land--it had beenintended that the trial should be completed over water. A descent wassuccessfully accomplished and the dirigible was anchored for the night, but a gale caused it so much damage that it had to be broken up. It hadachieved a speed of 30 feet per second with the motors developing only36 horse-power and, gathering from this what speed might have beenaccomplished with the full 170 horse-power, Zeppelin set about theconstruction of No. 3, with which a number of successful voyages weremade, proving the value of the type for military purposes. No. 4 was the most notable of the early Zeppelins, as much on account ofits disastrous end as by reason of any superior merit in comparison withNo. 3. The main innovation consisted in attaching a triangular keel tothe under side of the envelope, with two gaps beneath which the carswere suspended. Two Daimler Mercedes motors of 110 horse-power each wereplaced one in each car, and the vessel carried sufficient fuel for a60-hour cruise with the motors running at full speed. Each motor drove apair of three-bladed metal propellers rigidly attached to the frameworkof the envelope and about 15 feet in diameter. There was a verticalrudder at the stern of the envelope and horizontal controlling planeswere fixed on the sides of the envelope. The best performances and theend of this dirigible were summarised as follows by Major Squier:-- 'Its best performances were two long trips performed during the summerof 1908. The first, on July 4th, lasted exactly 12 hours, during whichtime it covered a distance of 235 miles, crossing the mountainsto Lucerne and Zurich, and returning to the balloon-house nearFriedrichshafen, on Lake Constance. The average speed on this tripwas 32 miles per hour. On August 4th, this airship attempted a 24-hourflight, which was one of the requirements made for its acceptance by theGovernment. It left Friedrichshafen in the morning with the intentionof following the Rhine as far as Mainz, and then returning to itsstarting-point, straight across the country. A stop of 3 hours 30minutes was made in the afternoon of the first day on the Rhine, torepair the engine. On the return, a second stop was found necessary nearStuttgart, due to difficulties with the motors, and some loss of gas. While anchored to the ground, a storm arose which broke loose theanchorage, and, as the balloon rose in the air, it exploded and tookfire (due to causes which have never been actually determined andpublished) and fell to the ground, where it was completely destroyed. Onthis journey, which lasted in all 31 hours 15 minutes, the airship wasin the air 20 hours 45 minutes, and covered a total distance of 378miles. 'The patriotism of the German nation was aroused. Subscriptions wereimmediately started, and in a short space of time a quarter of a millionpounds had been raised. A Zeppelin Society was formed to direct theexpenditure of this fund. Seventeen thousand pounds has been expended inpurchasing land near Friedrichshafen; workshops were erected, and it wasannounced that within one year the construction of eight airships of theZeppelin type would be completed. Since the disaster to 'Zeppelin IV. 'the Crown Prince of Germany made a trip in 'Zeppelin No. 3, ' which hadbeen called back into service, and within a very few days the GermanEmperor visited Friedrichshafen for the purpose of seeing the airship inflight. He decorated Count Zeppelin with the order of the Black Eagle. German patriotism and enthusiasm has gone further, and the "GermanAssociation for an Aerial Fleet" has been organised in sectionsthroughout the country. It announces its intention of building 50garages (hangars) for housing airships. ' By January of 1909, with well over a quarter of a million in hand forthe construction of Zeppelin airships, No. 3 was again brought out, probably in order to maintain public enthusiasm in respect of thepossible new engine of war. In March of that year No. 3 made a voyagewhich lasted for 4 hours over and in the vicinity of Lake Constance; itcarried 26 passengers for a distance of nearly 150 miles. Before the end of March, Count Zeppelin determined to voyage fromFriedrichshafen to Munich, together with the crew of the airship andfour military officers. Starting at four in the morning and ascertainingtheir route from the lights of railway stations and the ringing of bellsin the towns passed over, the journey was completed by nine o'clock, buta strong south-west gale prevented the intended landing. The airshipwas driven before the wind until three o'clock in the afternoon, when itlanded safely near Dingolfing; by the next morning the wind had fallenconsiderably and the airship returned to Munich and landed on the paradeground as originally intended. At about 3. 30 in the afternoon, thehomeward journey was begun, Friedrichshafen being reached at about 7. 30. These trials demonstrated that sufficient progress had been made tojustify the construction of Zeppelin airships for use with the Germanarmy. No. 3 had been manoeuvred safely if not successfully in half agale of wind, and henceforth it was known as 'SMS. Zeppelin I. , ' at thebidding of the German Emperor, while the construction of 'SMS. ZeppelinII. ' was rapidly proceeded with. The fifth construction of CountZeppelin's was 446 feet in length, 42 1/2 feet in diameter, and contained 530, 000 cubic feet of hydrogen gas in 17 separatecompartments. Trial flights were made on the 26th May, 1909, and a weeklater she made a record voyage of 940 miles, the route being from LakeConstance over Ulm, Nuremberg, Leipzig, Bitterfeld, Weimar, Heilbronn, and Stuttgart, descending near Goppingen; the time occupied in theflight was upwards of 38 hours. In landing, the airship collided with a pear-tree, which damaged thebows and tore open two sections of the envelope, but repairs on thespot enabled the return journey to Friedrichshafen to be begun 24 hourslater. In spite of the mishap the Zeppelin had once more proved itselfas a possible engine of war, and thenceforth Germany pinned its faithto the dirigible, only developing the aeroplane to such an extent asto keep abreast of other nations. By the outbreak of war, nearly 30Zeppelins had been constructed; considerably more than half of thesewere destroyed in various ways, but the experiments carried on witheach example of the type permitted of improvements being made. The firstfatality occurred in September, 1913, when the fourteenth Zeppelin to beconstructed, known as Naval Zeppelin L. 1, was wrecked in the North Seaby a sudden storm and her crew of thirteen were drowned. About threeweeks after this, Naval Zeppelin L. 2, the eighteenth in order ofbuilding, exploded in mid-air while manoeuvring over Johannisthal. Shewas carrying a crew of 25, who were all killed. By 1912 the success of the Zeppelin type brought imitators. Chief amongthem was the Schutte-Lanz, a Mannheim firm, which produced a rigiddirigible with a wooden framework, wire braced. This was not a cylinderlike the Zeppelin, but reverted to the cigar shape and contained aboutthe same amount of gas as the Zeppelin type. The Schutte-Lanz was madewith two gondolas rigidly attached to the envelope in which the gas bagswere placed. The method of construction involved greater weight than wasthe case with the Zeppelin, but the second of these vessels, built withthree gondolas containing engines, and a navigating cabin built intothe hull of the airship itself, proved quite successful as a naval scoutuntil wrecked on the islands off the coast of Denmark late in 1914. Thelast Schutte-Lanz to be constructed was used by the Germans for raidingEngland, and was eventually brought down in flames at Cowley. V. BRITISH AIRSHIP DESIGN As was the case with the aeroplane, Great Britain left France andGermany to make the running in the early days of airship construction;the balloon section of the Royal Engineers was compelled to confineits energies to work with balloons pure and simple until well afterthe twentieth century had dawned, and such experiments as were madein England were done by private initiative. As far back as 1900 DoctorBarton built an airship at the Alexandra Palace and voyaged acrossLondon in it. Four years later Mr E. T. Willows of Cardiff produced thefirst successful British dirigible, a semi-rigid 74 feet in length and18 feet in diameter, engined with a 7 horse-power Peugot twin-cylinderedmotor. This drove a two-bladed propeller at the stern for propulsion, and also actuated a pair of auxiliary propellers at the front whichcould be varied in their direction so as to control the right and leftmovements of the airship. This device was patented and the patent wastaken over by the British Government, which by 1908 found Mr Willow'swork of sufficient interest to regard it as furnishing data forexperiment at the balloon factory at Farnborough. In 1909, Willowssteered one of his dirigibles to London from Cardiff in a little lessthan ten hours, making an average speed of over 14 miles an hour. Thebest speed accomplished was probably considerably greater than this, for at intervals of a few miles, Willows descended near the earth toascertain his whereabouts with the help of a megaphone. It must be addedthat he carried a compass in addition to his megaphone. He set out forParis in November of 1910, reached the French coast, and landed nearDouai. Some damage was sustained in this landing, but, after repair, thetrip to Paris was completed. Meanwhile the Government balloon factory at Farnborough began airshipconstruction in 1907; Colonel Capper, R. E. , and S. F. Cody were jointlyconcerned in the production of a semi-rigid. Fifteen thicknesses ofgoldbeaters' skin--about the most expensive covering obtainable--wereused for the envelope, which was 25 feet in diameter. A slight shower ofrain in which the airship was caught led to its wreckage, owing to theabsorbent quality of the goldbeaters' skin, whereupon Capper and Codyset to work to reproduce the airship and its defects on a larger scale. The first had been named 'Nulli Secundus' and the second was named'Nulli Secundus II. ' Punch very appropriately suggested that the firstvessel ought to have been named 'Nulli Primus, ' while a possible thirdshould be christened 'Nulli Tertius. ' 'Nulli Secundus II. ' was fittedwith a 100 horse-power engine and had an envelope of 42 feet indiameter, the goldbeaters' skin being covered in fabric and the carbeing suspended by four bands which encircled the balloon envelope. In October of 1907, 'Nulli Secundus II. ' made a trial flight fromFarnborough to London and was anchored at the Crystal Palace. The windsprung up and took the vessel away from its mooring ropes, wrecking itafter the one flight. Stagnation followed until early in 1909, when a small airship fittedwith two 12 horse-power motors and named the 'Baby' was turned out fromthe balloon factory. This was almost egg-shaped, the blunt end beingforward, and three inflated fins being placed at the tail as controlmembers. A long car with rudder and elevator at its rear-end carriedthe engines and crew; the 'Baby' made some fairly successful flights andgave a good deal of useful data for the construction of later vessels. Next to this was 'Army Airship 2A 'launched early in 1910 and larger, longer, and narrower in design than the Baby. The engine was an 80horse-power Green motor which drove two pairs of propellers; smallinflated control members were fitted at the stern end of the envelope, which was 154 feet in length. The suspended car was 84 feet long, carrying both engines and crew, and the Willows idea of swivellingpropellers for governing the direction was used in this vessel. In Juneof that year a new, small-type dirigible, the 'Beta, ' was produced, driven by a 30 horse-power Green engine with which she flew over 3, 000miles. She was the most successful British dirigible constructed up tothat time, and her successor, the 'Gamma, ' was built on similar lines. The 'Gamma' was a larger vessel, however, produced in 1912, with flat, controlling fins and rudder at the rear end of the envelope, and withthe conventional long car suspended at some distance beneath the gasbag. By this time, the mooring mast, carrying a cap of which the concaveside fitted over the convex nose of the airship, had been originated. The cap was swivelled, and, when attached to it, an airship was heldnose on to the wind, thus reducing by more than half the dangersattendant on mooring dirigibles in the open. Private subscription under the auspices of the Morning Post got togethersufficient funds in 1910 for the purchase of a Lebaudy airship, whichwas built in France, flown across the Channel, and presented to the ArmyAirship Fleet. This dirigible was 337 feet long, and was driven by two135 horse-power Panhard motors, each of which actuated two propellers. The journey from Moisson to Aldershot was completed at a speed of 36miles an hour, but the airship was damaged while being towed into itsshed. On May of the following year, the Lebaudy was brought out for aflight, but, in landing, the guide rope fouled in trees and sheds andbrought the airship broadside on to the wind; she was driven into sometrees and wrecked to such an exteent that rebuilding was considered animpossibility. A Clement Bayard, bought by the army airship section, became scrap after even less flying than had been accomplished by theLebaudy. In April of 1910, the Admiralty determined on a naval air service, and set about the production of rigid airships which should be able tocompete with Zeppelins as naval scouts. The construction was entrustedto Vickers, Ltd. , who set about the task at their Barrow works and builtsomething which, when tested after a year's work, was found incapableof lifting its own weight. This defect was remedied by a series ofalterations, and meanwhile the unofficial title of 'Mayfly' was given tothe vessel. Taken over by the Admiralty before she had passed any flying tests, the 'Mayfly' was brought out on September 24th, 1911, for a trial trip, being towed out from her shed by a tug. When half out from the shed, the envelope was caught by a light cross-wind, and, in spite of the pullfrom the tug, the great fabric broke in half, nearly drowning the crew, who had to dive in order to get clear of the wreckage. There was considerable similarity in form, though not in performance, between the Mayfly and the prewar Zeppelin. The former was 510 feet inlength, cylindrical in form, with a diameter of 48 feet, and dividedinto 19 gas-bag compartments. The motive power consisted of two 200horse-power Wolseley engines. After its failure, the Naval Air Servicebought an Astra-Torres airship from France and a Parseval from Germany, both of which proved very useful in the early days of the War, doingpatrol work over the Channel before the Blimps came into being. Early in 1915 the 'Blimp' or 'S. S. ' type of coastal airship was evolvedin response to the demand for a vessel which could be turned out quicklyand in quantities. There was urgent demand, voiced by Lord Fisher, fora type of vessel capable of maintaining anti-submarine patrol off theBritish coasts, and the first S. S. Airships were made by combining agasbag with the most available type of aeroplane fuselage and engine, and fitting steering gear. The 'Blimp' consisted of a B. E. Fuselage withengine and geared-down propeller, and seating for pilot and observer, attached to an envelope about 150 feet in length. With a speed ofbetween 35 and 40 miles an hour, the 'Blimp' had a cruising capacity ofabout ten hours; it was fitted with wireless set, camera, machine-gun, and bombs, and for submarine spotting and patrol work generally itproved invaluable, though owing to low engine power and comparativelysmall size, its uses were restricted to reasonably fair weather. Forwork farther out at sea and in all weathers, airships known as the coastpatrol type, and more commonly as 'coastals, ' were built, and laterthe 'N. S. ' or North Sea type, still larger and more weather-worthy, followed. By the time the last year of the War came, Britain led theworld in the design of non-rigid and semi-rigid dirigibles. The 'S. S. 'or 'Blimp' had been improved to a speed of 50 miles an hour, carrying acrew of three, and the endurance record for the type was 18 1/2 hours, while one of them had reached a height of 10, 000 feet. The North Seatype of non-rigid was capable of travelling over 20 hours at full speed, or forty hours at cruising speed, and the number of non-rigids belongingto the British Navy exceeded that of any other country. It was owing to the incapacity--apparent or real--of the Britishmilitary or naval designers to produce a satisfactory rigid airship thatthe 'N. S. ' airship was evolved. The first of this type was producedin 1916, and on her trials she was voted an unqualified success, inconsequence of which the building of several more was pushed on. Theenvelope, of 360, 000 cubic feet capacity, was made on the Astra-Torresprinciple of three lobes, giving a trefoil section. The ship carriedfour fins, to three of which the elevator and rudder flaps wereattached; petrol tanks were placed inside the envelope, under whichwas rigged a long covered-in car, built up of a light steel tubularframework 35 feet in length. The forward portion was covered withduralumin sheeting, an aluminium alloy which, unlike aluminium itself, is not affected by the action of sea air and water, and the remainderwith fabric laced to the framework. Windows and port-holes were providedto give light to the crew, and the controls and navigating instrumentswere placed forward, with the sleeping accommodation aft. The engineswere mounted in a power unit structure, separate from the car andconnected by wooden gang ways supported by wire cables. A completeelectrical installation of two dynamos and batteries for lights, signalling lamps, wireless, telephones, etc. , was carried, and themotive power consisted of either two 250 horse-power Rolls-Royce enginesor two 240 horse-power Fiat engines. The principal dimensions of thistype are length 262 feet, horizontal diameter 56 feet 9 inches, verticaldiameter 69 feet 3 inches. The gross lift is 24, 300 lbs. And thedisposable lift without crew, petrol, oil, and ballast 8, 500 lbs. Thenormal crew carried for patrol work was ten officers and men. This typeholds the record of 101 hours continuous flight on patrol duty. In the matter of rigid design it was not until 1913 that the BritishAdmiralty got over the fact that the 'Mayfly' would not, and decided ona further attempt at the construction of a rigid dirigible. Thecontract for this was signed in March of 1914; work was suspended in thefollowing February and begun again in July, 1915, but it was not untilJanuary of 1917 that the ship was finished, while her trials were notcompleted until March of 1917, when she was taken over by the Admiralty. The details of the construction and trial of this vessel, known as 'No. 9, ' go to show that she did not quite fill the contract requirements inrespect of disposable lift until a number of alterations had been made. The contract specified that a speed of at least 45 miles per hour was tobe attained at full engine power, while a minimum disposable lift of 5tons was to be available for movable weights, and the airship was tobe capable of rising to a height of 2, 000 feet. Driven by four WolseleyMaybach engines of 180 horse-power each, the lift of the vessel was notsufficient, so it was decided to remove the two engines in the aftercar and replace them by a single engine of 250 horsepower. With this thevessel reached the contract speed of 45 miles per hour with a cruisingradius of 18 hours, equivalent to 800 miles when the engines wererunning at full speed. The vessel served admirably as a trainingairship, for, by the time she was completed, the No. 23 class of rigidairship had come to being, and thus No. 9 was already out of date. Three of the 23 class were completed by the end of 1917; it wasstipulated that they should be built with a speed of at least 55 milesper hour, a minimum disposable lift of 8 tons, and a capability ofrising at an average rate of not less than 1, 000 feet per minute to aheight of 3, 000 feet. The motive power consisted of four 250 horse-powerRolls-Royce engines, one in each of the forward and after cars and twoin a centre car. Four-bladed propellers were used throughout the ship. A 23X type followed on the 23 class, but by the time two ships had beencompleted, this was practically obsolete. The No. 31 class followed the23X; it was built on Schutte-Lanz lines, 615 feet in length, 66 feetdiameter, and a million and a half cubic feet capacity. The hull wassimilar to the later types of Zeppelin in shape, with a tapering sternand a bluff, rounded bow. Five cars each carrying a 250 horse-powerRolls-Royce engine, driving a single fixed propeller, were fitted, andon her trials R. 31 performed well, especially in the matter of speed. But the experiment of constructing in wood in the Schutte-Lanz wayadopted with this vessel resulted in failure eventually, and the typewas abandoned. Meanwhile, Germany had been pushing forward Zeppelin designand straining every nerve in the improvement of rigid dirigibleconstruction, until L. 33 was evolved; she was generally known asa super-Zeppelin, and on September 24th, 1916, six weeks after herlaunching, she was damaged by gun-fire in a raid over London, beingeventually compelled to come to earth at Little Wigborough in Essex. Thecrew gave themselves up after having set fire to the ship, and thoughthe fabric was totally destroyed, the structure of the hull remainedintact, so that just as Germany was able to evolve the Gotha bomber fromthe Handley-Page delivered at Lille, British naval constructors were ableto evolve the R. 33 type of airship from the Zeppelin framework deliveredat Little Wigborough. Two vessels, R. 33 and R. 34, were laid down forcompletion; three others were also put down for construction, but, whileR. 33 and R. 34 were built almost entirely from the data gathered fromthe wrecked L. 33, the three later vessels embody more modern design, including a number of improvements, and more especially greaterdisposable lift. It has been commented that while the Britishauthorities were building R. 33 and R. 34, Germany constructed 30Zeppelins on 4 slips, for which reason it may be reckoned a matter forcongratulation that the rigid airship did not decide the fate of theWar. The following particulars of construction of the R. 33 and R. 34types are as given by Major Whale in his survey of British Airships:-- 'In all its main features the hull structure of R. 33 and R. 34 followsthe design of the wrecked German Zeppelin airship L. 33. 'The hullfollows more nearly a true stream-line shape than in the previous shipsconstructed of duralumin, in which a greater proportion of the greaterlength was parallel-sided. The Germans adopted this new shape fromthe Schutte-Lanz design and have not departed from this practice. Thisconsists of a short, parallel body with a long, rounded bow and a longtapering stem culminating in a point. The overall length of the ship is643 feet with a diameter of 79 feet and an extreme height of 92 feet. 'The type of girders in this class has been much altered from thosein previous ships. The hull is fitted with an internal triangular keelthroughout practically the entire length. This forms the main corridorof the ship, and is fitted with a footway down the centre for its entirelength. It contains water ballast and petrol tanks, bomb storage andcrew accommodation, and the various control wires, petrol pipes, andelectric leads are carried along the lower part. 'Throughout this internal corridor runs a bridge girder, from whichthe petrol and water ballast tanks are supported. These tanks are soarranged that they can be dropped clear of the ship. Amidships is thecabin space with sufficient room for a crew of twenty-five. Hammocks canbe swung from the bridge girder before mentioned. 'In accordance with the latest Zeppelin practice, monoplane rudders andelevators are fitted to the horizontal and vertical fins. 'The ship is supported in the air by nineteen gas bags, which give atotal capacity of approximately two million cubic feet of gas. The grosslift works out at approximately 59 1/2 tons, of which the total fixedweight is 33 tons, giving a disposable lift of 26 1/2 tons. 'The arrangement of cars is as follows: At the forward end the controlcar is slung, which contains all navigating instruments and the variouscontrols. Adjoining this is the wireless cabin, which is also fittedfor wireless telephony. Immediately aft of this is the forward power carcontaining one engine, which gives the appearance that the whole is onelarge car. 'Amidships are two wing cars, each containing a single engine. Theseare small and just accommodate the engines with sufficient room formechanics to attend to them. Further aft is another larger car whichcontains an auxiliary control position and two engines. 'It will thus be seen that five engines are installed in the ship;these are all of the same type and horsepower, namely, 250 horse-powerSunbeam. R. 33 was constructed by Messrs Armstrong, Whitworth, Ltd. ;while her sister ship R. 34 was built by Messrs Beardmore on the Clyde. ' Of the two vessels, R. 34 appeared rather more airworthy than her sistership; the lift of the ship justified the carrying of a greater quantityof fuel than had been provided for, and, as she was considered suitablefor making a Transatlantic crossing, extra petrol tanks were fitted inthe hull and a new type of outer cover was fitted with a view to hermaking the Atlantic crossing. She made a 21-hour cruise over the Northof England and the South of Scotland at the end of May, 1919, andsubsequently went for a longer cruise over Denmark, the Baltic, and thenorth coast of Germany, remaining in the air for 56 hours in spiteof very bad weather conditions. Finally, July 2nd was selected as thestarting date for the cross Atlantic flight; the vessel was commandedby Major G. H. Scott, A. F. C. , with Captain G. S. Greenland as firstofficer, Second-Lieut. H. F. Luck as second officer, and Lieut. J. D. Shotter as engineer officer. There were also on board Brig. -Gen. E. P. Maitland, representing the Air Ministry, Major J. E. M. Pritchard, representing the Admiralty, and Lieut. -Col. W. H. Hemsley of the ArmyAviation Department. In addition to eight tons of petrol, R. 34 carried atotal number of 30 persons from East Fortune to Long Island, N. Y. There being no shed in America capable of accommodating the airship, she had to be moored in the open for refilling with fuel and gas, and tomake the return journey almost immediately. Brig. -Gen. Maitland's account of the flight, in itself a record asinteresting as valuable, divides the outward journey into two mainstages, the first from East Fortune to Trinity Bay, Newfoundland, adistance of 2, 050 sea miles, and the second and more difficult stageto Mineola Field, Long Island, 1, 080 sea miles. An easy journeywas experienced until Newfoundland was reached, but then storms andelectrical disturbances rendered it necessary to alter the course, inconsequence of which petrol began to run short. Head winds rendered theshortage still more acute, and on Saturday, July 5th, a wireless signalwas sent out asking for destroyers to stand by to tow. However, after ananxious night, R. 33 landed safely at Mineola Field at 9. 55 a. M. On July6th, having accomplished the journey in 108 hours 12 minutes. She remained at Mineola until midnight of July 9th, when, althoughit had been intended that a start should be made by daylight for thebenefit of New York spectators, an approaching storm caused preparationsto be advanced for immediate departure. She set out at 5. 57 a. M. By British summer time, and flew over New York in the full glareof hundreds of searchlights before heading out over the Atlantic. Afollowing wind assisted the return voyage, and on July 13th, at 7. 57a. M. , R. 34 anchored at Pulham, Norfolk, having made the return journeyin 75 hours 3 minutes, and proved the suitability of the dirigiblefor Transatlantic commercial work. R. 80, launched on July 19th, 1920, afforded further proof, if this were needed. It is to be noted that nearly all the disasters to airships have beencaused by launching and landing--the type is safe enough in the air, under its own power, but its bulk renders it unwieldy for groundhandling. The German system of handling Zeppelins in and out of theirsheds is, so far, the best devised: this consists of heavy trucksrunning on rails through the sheds and out at either end; on descending, the trucks are run out, and the airship is securely attached to themoutside the shed; the trucks are then run back into the shed, taking theairship with them, and preventing any possibility of the wind drivingthe envelope against the side of the shed before it is safely housed;the reverse process is adopted in launching, which is thus rendered assimple as it is safe. VI. THE AIRSHIP COMMERCIALLY Prior to the war period, between the years 1910 and 1914, a Germanundertaking called the Deutsche Luftfahrt Actien Gesellschaft conducteda commercial Zeppelin service in which four airships known as theSachsan, Hansa, Victoria Louise, and Schwaben were used. During the fouryears of its work, the company carried over 17, 000 passengers, and over100, 000 miles were flown without incurring one fatality and with onlyminor and unavoidable accidents to the vessels composing the service. Although a number of English notabilities made voyages in theseairships, the success of this only experiment in commercial aerostationseems to have been forgotten since the war. There was beyond doubt amilitary aim in this apparently peaceful use of Zeppelin airships; it ispast question now that all Germany's mechanical development in respectof land sea, and air transport in the years immediately preceding thewar, was accomplished with the ulterior aim of military conquest, but, at the same time, the running of this service afforded proof of thepossibility of establishing a dirigible service for peaceful ends, andafforded proof too, of the value of the dirigible as a vessel of purelycommercial utility. In considering the possibility of a commercial dirigible service, itis necessary always to bear in mind the disadvantages of first cost andupkeep as compared with the aeroplane. The building of a modern rigidis an exceedingly costly undertaking, and the provision of an efficientsupply of hydrogen gas to keep its compartments filled is a very largeitem in upkeep of which the heavier-than-air machine goes free. Yetthe future of commercial aeronautics so far would seem to lie with thedirigible where very long voyages are in question. No matter how theaeroplane may be improved, the possibility of engine failure alwaysremains as a danger for work over water. In seaplane or flying boatform, the danger is still present in a rough sea, though in the AmericanTransatlantic flight, N. C. 3, taxi-ing 300 miles to the Azores afterhaving fallen to the water, proved that this danger is not so acute asis generally assumed. Yet the multiple-engined rigid, as R. 34 showed onher return voyage, may have part of her power plant put out of actionaltogether and still complete her voyage very successfully, which, inthe case of mail carrying and services run strictly to time, gives heran enormous advantage over the heavier-than-air machine. 'For commercial purposes, ' General Sykes has remarked, 'the airship iseminently adapted for long distance journeys involving non-stop flights. It has this inherent advantage over the aeroplane, that while thereappears to be a limit to the range of the aeroplane as at presentconstructed, there is practically no limit whatever to that of theairship, as this can be overcome by merely increasing the size. It thusappears that for such journeys as crossing the Atlantic, or crossingthe Pacific from the west coast of America to Australia or Japan, theairship will be peculiarly suitable. It having been conceded that thescope of the airship is long distance travel, the only type which needbe considered for this purpose is the rigid. The rigid airship is stillin an embryonic state, but sufficient has already been accomplishedin this country, and more particularly in Germany, to show that withincreased capacity there is no reason why, within a few years' time, airships should not be built capable of completing the circuit of theglobe and of conveying sufficient passengers and merchandise to rendersuch an undertaking a paying proposition. ' The British R. 38 class, embodying the latest improvements in airshipdesign outside Germany, gives a gross lift per airship of 85 tons and anet lift of about 45 tons. The capacity of the gas bags is about twoand three-quarter million cubic feet, and, travelling at the rate of45 miles per hour, the cruising range of the vessel is estimated at 8. 8days. Six engines, each of 350 horse-power, admit of an extreme speed of70 miles per hour if necessary. The last word in German design is exemplified in the rigids L. 70 andL. 71, together with the commercial airship 'Bodensee. ' Previous to theconstruction of these, the L. 65 type is noteworthy as being the firstZeppelin in which direct drive of the propeller was introduced, togetherwith an improved and lighter type of car. L. 70 built in 1918 anddestroyed by the British naval forces, had a speed of about 75 miles perhour; L. 71 had a maximum speed of 72 miles per hour, a gas bag capacityof 2, 420, 000 cubic feet, and a length of 743 feet, while the total liftwas 73 tons. Progress in design is best shown by the progress in usefulload; in the L. 70 and L. 71 class, this has been increased to 58. 3 percent, while in the Bodensee it was ever higher. As was shown in R. 34's American flight, the main problem in connectionwith the commercial use of dirigibles is that of mooring in the open. The nearest to a solution of this problem, so far, consists in the mastcarrying a swivelling cap; this has been tried in the British servicewith a non-rigid airship, which was attached to a mast in open countryin a gale of 52 miles an hour without the slightest damage to theairship. In its commercial form, the mast would probably take theform of a tower, at the top of which the cap would revolve so thatthe airship should always face the wind, the tower being used forembarkation and disembarkation of passengers and the provision of fueland gas. Such a system would render sheds unnecessary except in case ofrepairs, and would enormously decrease the establishment charges of anycommercial airship. All this, however, is hypothetical. Remains the airship of to-day, developed far beyond the promise of five years ago, capable, as hasbeen proved by its achievements both in Britain and in Germany, ofundertaking practically any given voyage with success. VII. KITE BALLOONS As far back as the period of the Napoleonic wars, the balloon wasgiven a place in warfare, but up to the Franco-Prussian Prussian Warof 1870-71 its use was intermittent. The Federal forces made use ofballoons to a small extent in the American Civil War; they came to greatprominence in the siege of Paris, carrying out upwards of three millionletters and sundry carrier pigeons which took back messages into thebesieged city. Meanwhile, as captive balloons, the German and otherarmies used them for observation and the direction of artillery fire. Inthis work the ordinary spherical balloon was at a grave disadvantage; ifa gust of wind struck it, the balloon was blown downward and downwind, generally twirling in the air and upsetting any calculations andestimates that might be made by the observers, while in a wind of 25miles an hour it could not rise at all. The rotatory movement caused bywind was stopped by an experimenter in the Russo-Japanese war, who fixedto the captive observation balloons a fin which acted as a rudder. Thisdid not stop the balloon from being blown downward and away from itsmooring station, but this tendency was overcome by a modificationdesigned in Germany by the Parseval-Siegsfield Company, which originatedwhat has since become familiar as the 'Sausage' or kite balloon. Thisis so arranged that the forward end is tilted up into the wind, and theunderside of the gas bag, acting as a plane, gives the balloon a liftingtendency in a wind, thus counteracting the tendency of the wind to blowit downward and away from its mooring station. Smaller bags are fittedat the lower and rear end of the balloon with openings that face intothe wind; these are thus kept inflated, and they serve the purpose of arudder, keeping the kite balloon steady in the air. Various types of kite balloon have been introduced; the original GermanParseval-Siegsfield had a single air bag at the stern end, which wasmodified to two, three, or more lobes in later varieties, while anAmerican experimental design attempted to do away with the attachedlobes altogether by stringing out a series of small air bags, kitefashion, in rear of the main envelope. At the beginning of the War, Germany alone had kite balloons, for the authorities of the Alliedarmies con-sidered that the bulk of such a vessel rendered it tooconspicuous a mark to permit of its being serviceable. The Belgianarm alone possessed two which, on being put into service, were foundextremely useful. The French followed by constructing kite balloons atChalais Meudon, and then, after some months of hostilities and with theexample of the Royal Naval Air Service to encourage them, the Britishmilitary authorities finally took up the construction and use of kiteballoons for artillery-spotting and general observation purposes. Although many were brought down by gun-fire, their uses far outweighedtheir disadvantages, and toward the end of the War, hardly a mile offront was without its 'Sausage. ' For naval work, kite balloons were carried in a specially constructedhold in the forepart of certain vessels; when required for use, thecovering of the hold was removed, the kite balloon inflated and releasedto the required height by means of winches as in the case of theland work. The perfecting of the 'Coastal' and N. S. Types of airship, together with the extension of wireless telephony between airship andcruiser or other warship, in all probability will render the use of thekite balloon unnecessary in connection with naval scouting. But, duringthe War, neither wireless telephony nor naval airships had developedsufficiently to render the Navy independent of any means that might cometo hand, and the fitting of kite balloons in this fashion filled a needof the times. A necessary accessory of the kite balloon is the parachute, which hasa long history. Da Vinci and Veranzio appear to have been the firstexponents, the first in the theory and the latter in the practice ofparachuting. Montgolfier experimented at Annonay before he constructedhis first hot air-balloon, and in 1783 a certain Lenormand dropped froma tree in a parachute. Blanchard the balloonist made a spectacleof parachuting, and made it a financial success; Cocking, in 1836, attempted to use an inverted form of parachute; taken up to a heightof 3, 000 feet, he was cut adrift, when the framework of the parachutecollapsed and Cocking was killed. The rate of fall is slow in parachuting to the ground. Frau Poitevin, making a descent from a height of 6, 000 feet, took 45 minutes to reachthe ground, and, when she alighted, her husband, who had taken her up, had nearly got his balloon packed up. Robertson, another parachutist issaid to have descended from a height of 10, 000 feet in 35 minutes, orat a rate of nearly 5 feet per second. During the War Brigadier-GeneralMaitland made a parachute descent from a height of 10, 000 feet, the timetaken being about 20 minutes. The parachute was developed considerably during the War period, the mainrequirement, that of certainty in opening, being considerably developed. Considered a necessary accessory for kite balloons, the parachute wasalso partially adopted for use with aeroplanes in the later War period, when it was contended that if a machine were shot down in flames, itsoccupants would be given a far better chance of escape if they hadparachutes. Various trials were made to demonstrate the extremeefficiency of the parachute in modern form, one of them being a descentfrom the upper ways of the Tower Bridge to the waters of the Thames, inwhich short distance the 'Guardian Angel' type of parachute opened andcushioned the descent for its user. For dirigibles, balloons, and kite balloons the parachute is anessential. It would seem to be equally essential in the case ofheavier-than-air machines, but this point is still debated. Certainlyit affords the occupant of a falling aeroplane a chance, no matter howslender, of reaching the ground in safety, and, for that reason, itwould seem to have a place in aviation as well as in aerostation. PART IV. ENGINE DEVELOPMENT I. THE VERTICAL TYPE The balloon was but a year old when the brothers Robert, in 1784attempted propulsion of an aerial vehicle by hand-power, and succeeded, to a certain extent, since they were able to make progress when therewas only a slight wind to counteract their work. But, as may be easilyunderstood, the manual power provided gave but a very slow speed, and inany wind it all the would-be airship became an uncontrolled balloon. Henson and Stringfellow, with their light steam engines, were first toattempt conquest of the problem of mechanical propulsion in theair; their work in this direction is so fully linked up with theirconstructed models that it has been outlined in the section dealingwith the development of the aeroplane. But, very shortly after thesetwo began, there came into the field a Monsieur Henri Giffard, who firstachieved success in the propulsion by mechanical means of dirigibleballoons, for his was the first airship to fly against the wind. He employed a small steam-engine developing about 3 horse-power andweighing 350 lbs. With boiler, fitting the whole in a car suspended fromthe gas-bag of his dirigible. The propeller which this engine workedwas 11 feet in diameter, and the inventor, who made several flights, obtained a speed of 6 miles an hour against a slight wind. The powerwas not sufficient to render the invention practicable, as the dirigiblecould only be used in calm weather, but Giffard was sufficientlyencouraged by his results to get out plans for immense dirigibles, which through lack of funds he was unable to construct. When, later, hisinvention of the steam-injector gave him the means he desired, he becameblind, and in 1882 died, having built but the one famous dirigible. This appears to have been the only instance of a steam engine beingfitted to a dirigible; the inherent disadvantage of this form of motivepower is that a boiler to generate the steam must be carried, and this, together with the weight of water and fuel, renders the steam engineuneconomical in relation to the lift either of plane or gas-bag. Again, even if the weight could be brought down to a reasonable amount, theattention required by steam plant renders it undesirable as a motivepower for aircraft when compared with the internal combustion engine. Maxim, in Artificial and Natural Flight, details the engine which heconstructed for use with his giant experimental flying machine, and hisdescription is worthy of reproduction since it is that of the only steamengine besides Giffard's, and apart from those used for the propulsionof models, designed for driving an aeroplane. 'In 1889, ' Maxim says, 'I had my attention drawn to some very thin, strong, and comparativelycheap tubes which were being made in France, and it was only after I hadseen these tubes that I seriously considered the question of making aflying machine. I obtained a large quantity of them and found that theywere very light, that they would stand enormously high pressures, andgenerate a very large quantity of steam. Upon going into a mathematicalcalculation of the whole subject, I found that it would be possible tomake a machine on the aeroplane system, driven by a steam engine, whichwould be sufficiently strong to lift itself into the air. I first madedrawings of a steam engine, and a pair of these engines was afterwardsmade. These engines are constructed, for the most part, of a very highgrade of cast steel, the cylinders being only 3/32 of an inch thick, the crank shafts hollow, and every part as strong and light as possible. They are compound, each having a high-pressure piston with an area of20 square inches, a low-pressure piston of 50. 26 square inches, and acommon stroke of 1 foot. When first finished they were found to weigh300 lbs. Each; but after putting on the oil cups, felting, painting, andmaking some slight alterations, the weight was brought up to 320 lbs. Each, or a total of 640 lbs. For the two engines, which have sincedeveloped 362 horsepower with a steam pressure of 320 lbs. Per squareinch. ' The result is remarkable, being less than 2 lbs. Weight per horse-power, especially when one considers the state of development to which thesteam engine had attained at the time these experiments were made. Thefining down of the internal combustion engine, which has done so much tosolve the problems of power in relation to weight for use with aircraft, had not then been begun, and Maxim had nothing to guide him, so faras work on the part of his predecessors was concerned, save theexperimental engines of Stringfellow, which, being constructed on sosmall a scale in comparison with his own, afforded little guidance. Concerning the factor of power, he says: 'When first designing thisengine, I did not know how much power I might require from it. I thoughtthat in some cases it might be necessary to allow the high-pressuresteam to enter the low-pressure cylinder direct, but as this wouldinvolve a considerable loss, I constructed a species of injector. Thisinjector may be so adjusted that when the steam in the boiler risesabove a certain predetermined point, say 300 lbs. , to the square inch, it opens a valve and escapes past the high-pressure cylinder instead ofblowing off at the safety valve. In escaping through this valve, a fallof about 200 lbs. Pressure per square inch is made to do work on thesurrounding steam and drive it forward in the pipe, producing a pressureon the low-pressure piston considerably higher than the back-pressure onthe high-pressure piston. In this way a portion of the work which wouldotherwise be lost is utilised, and it is possible, with an unlimitedsupply of steam, to cause the engines to develop an enormous amount ofpower. ' With regard to boilers, Maxim writes, 'The first boiler which I made was constructed something on theHerreshof principle, but instead of having one simple pipe in one verylong coil, I used a series of very small and light pipes, connected insuch a manner that there was a rapid circulation through the whole--thetubes increasing in size and number as the steam was generated. Iintended that there should be a pressure of about 100 lbs. More on thefeed water end of the series than on the steam end, and I believed thatthis difference in pressure would be sufficient to ensure direct andpositive circulation through every tube in the series. The first boilerwas exceedingly light, but the workmanship, as far as putting the tubestogether was concerned, was very bad, and it was found impossible to soadjust the supply of water as to make dry steam without overheating anddestroying the tubes. 'Before making another boiler I obtained a quantity of copper tubes, about 8 feet long, 3/8 inch external diameter, and 1/50 of an inchthick. I subjected about 100 of these tubes to an internal pressure of1 ton per square inch of cold kerosene oil, and as none of them leakedI did not test any more, but commenced my experiments by placing someof them in a white-hot petroleum fire. I found that I could evaporateas much as 26 1/2 lbs. Of water per square foot of heating surface perhour, and that with a forced circulation, although the quantity of waterpassing was very small but positive, there was no danger of overheating. I conducted many experiments with a pressure of over 400 lbs. Per squareinch, but none of the tubes failed. I then mounted a single tube in awhite-hot furnace, also with a water circulation, and found that it onlyburst under steam at a pressure of 1, 650 lbs. Per square inch. A largeboiler, having about 800 square feet of heating surface, including thefeed-water heater, was then constructed. This boiler is about 4 1/2 feetwide at the bottom, 8 feet long and 6 feet high. It weighs, with thecasing, the dome, and the smoke stack and connections, a little lessthan 1, 000 lbs. The water first passes through a system of smalltubes--1/4 inch in diameter and 1/60 inch thick--which were placed atthe top of the boiler and immediately over the large tubes.... Thisfeed-water heater is found to be very effective. It utilises the heatof the products of combustion after they have passed through the boilerproper and greatly reduces their temperature, while the feed-waterenters the boiler at a temperature of about 250 F. A forced circulationis maintained in the boiler, the feed-water entering through a springvalve, the spring valve being adjusted in such a manner that thepressure on the water is always 30 lbs. Per square inch in excess ofthe boiler pressure. This fall of 30 lbs. In pressure acts upon thesurrounding hot water which has already passed through the tubes, anddrives it down through a vertical outside tube, thus ensuring a positiveand rapid circulation through all the tubes. This apparatus is found toact extremely well. ' Thus Maxim, who with this engine as power for his large aeroplaneachieved free flight once, as a matter of experiment, though for whatdistance or time the machine was actually off the ground is matter fordebate, since it only got free by tearing up the rails which were tohave held it down in the experiment. Here, however, was a steam enginewhich was practicable for use in the air, obviously, and only the rapidsuccess of the internal combustion engine prevented the steam-producingtype from being developed toward perfection. The first designers of internal combustion engines, knowing nothingof the petrol of these days, constructed their examples with a view tousing gas as fuel. As far back as 1872 Herr Paul Haenlein obtained aspeed of about 10 miles an hour with a balloon propelled by an internalcombustion engine, of which the fuel was gas obtained from the balloonitself. The engine in this case was of the Lenoir type, developingsome 6 horse-power, and, obviously, Haenlein's flights were purelyexperimental and of short duration, since he used the gas that sustainedhim and decreased the lifting power of his balloon with every stroke ofthe piston of his engine. No further progress appears to have been madewith the gas-consuming type of internal combustion engine for workwith aircraft; this type has the disadvantage of requiring either agas-producer or a large storage capacity for the gas, either of whichmakes the total weight of the power plant much greater than that ofa petrol engine. The latter type also requires less attention whenworking, and the fuel is more convenient both for carrying and in thematter of carburation. The first airship propelled by the present-day type of internalcombustion engine was constructed by Baumgarten and Wolfert in 1879at Leipzig, the engine being made by Daimler with a view to working onbenzine--petrol as a fuel had not then come to its own. The constructionof this engine is interesting since it was one of the first of Daimler'smake, and it was the development brought about by the experimentalseries of which this engine was one that led to the success of themotor-car in very few years, incidentally leading to that fining down ofthe internal combustion engine which has facilitated the developmentof the aeroplane with such remarkable rapidity. Owing to the faultyconstruction of the airship no useful information was obtained fromDaimler's pioneer installation, as the vessel got out of controlimmediately after it was first launched for flight, and was wrecked. Subsequent attempts at mechanically-propelled flight by Wolfert ended, in 1897, in the balloon being set on fire by an explosion of benzinevapour, resulting in the death of both the aeronauts. Daimler, from 1882 onward, devoted his attention to the perfecting ofthe small, high-speed petrol engine for motor-car work, and owing tohis efforts, together with those of other pioneer engine-builders, themotorcar was made a success. In a few years the weight of this type ofengine was reduced from near on a hundred pounds per horse-power to lessthan a tenth of that weight, but considerable further improvement had tobe made before an engine suitable for use with aircraft was evolved. The increase in power of the engines fitted to airships has madesteady progress from the outset; Haenlein's engine developed about 6horse-power; the Santos-Dumont airship of 1898 was propelled by a motorof 4 horse-power; in 1902 the Lebaudy airship was fitted with an engineof 40 horse-power, while, in 1910, the Lebaudy brothers fitted anengine of nearly 300 horsepower to the airship they were thenconstructing--1, 400 horse-power was common in the airships of the Warperiod, and the later British rigids developed yet more. Before passing on to consideration of the petrol-driven type of engine, it is necessary to accord brief mention to the dirigible constructed in1884 by Gaston and Albert Tissandier, who at Grenelle, France, achieveda directed flight in a wind of 8 miles an hour, obtaining their powerfor the propeller from 1 1/3 horse-power Siemens electric motor, whichweighed 121 lbs. And took its current from a bichromate battery weighing496 lbs. A two-bladed propeller, 9 feet in diameter, was used, andthe horse-power output was estimated to have run up to 1 1/2 as thedirigible successfully described a semicircle in a wind of 8 miles anhour, subsequently making headway transversely to a wind of 7 milesan hour. The dirigible with which this motor was used was of theconventional pointed-end type, with a length of 92 feet, diameter of 30feet, and capacity of 37, 440 cubic feet of gas. Commandant Renard, ofthe French army balloon corps, followed up Tissandier's attempt inthe next year--1885--making a trip from Chalais-Meudon to Paris andreturning to the point of departure quite successfully. In this case themotive power was derived from an electric plant of the type used bythe Tissandiers, weighing altogether 1, 174 lbs. , and developing9 horsepower. A speed of 14 miles an hour was attained with thisdirigible, which had a length of 165 feet, diameter of 27 feet, andcapacity of 65, 836 cubic feet of gas. Reverting to the petrol-fed type again, it is to be noted thatSantos-Dumont was practically the first to develop the use of theordinary automobile engine for air work--his work is of such importancethat it has been considered best to treat of it as one whole, anddetails of the power plants are included in the account of hisexperiments. Coming to the Lebaudy brothers and their work, their engineof 1902 was a 40 horse-power Daimler, four-cylindered; it was virtuallya large edition of the Daimler car engine, the arrangement of thevarious details being on the lines usually adopted for the standardDaimler type of that period. The cylinders were fully water-jacketed, and no special attempt toward securing lightness for air work appears tohave been made. The fining down of detail that brought weight to such limits as wouldfit the engine for work with heavier-than-air craft appears to havewaited for the brothers Wright. Toward the end of 1903 they fittedto their first practicable flying machine the engine which made thehistoric first aeroplane flight; this engine developed 30 horse-power, and weighed only about 7 lbs. Per horse-power developed, its design andworkmanship being far ahead of any previous design in this respect, withthe exception of the remarkable engine, designed by Manly, installed inLangley's ill-fated aeroplane--or 'aerodrome, ' as he preferred to callit--tried in 1903. The light weight of the Wright brothers' engine did not necessitate ahigh number of revolutions per minute to get the requisite power; thespeed was only 1, 300 revolutions per minute, which, with a pistonstroke of 3. 94 inches, was quite moderate. Four cylinders were used, the cylinder diameter being 4. 42 inches; the engine was of thevertical type, arranged to drive two propellers at a rate of about 350revolutions per minute, gearing being accomplished by means of chaindrive from crank-shaft end to propeller spindle. The methods adopted by the Wrights for obtaining a light-weight enginewere of considerable interest, in view of the fact that the honourof first achieving flight by means of the driven plane belongs tothem--unless Ader actually flew as he claimed. The cylinders of thisfirst Wright engine were separate castings of steel, and only thebarrels were jacketed, this being done by fixing loose, thin aluminiumcovers round the outside of each cylinder. The combustion head and valvepockets were cast together with the cylinder barrel, and were not watercooled. The inlet valves were of the automatic type, arranged on thetops of the cylinders, while the exhaust valves were also overhead, operated by rockers and push-rods. The pistons and piston rings wereof the ordinary type, made of cast-iron, and the connecting rods werecircular in form, with a hole drilled down the middle of each to reducethe weight. Necessity for increasing power and ever lighter weight in relation tothe power produced has led to the evolution of a number of differentdesigns of internal combustion engines. It was quickly realised thatincreasing the number of cylinders on an engine was a better way ofgetting more power than that of increasing the cylinder diameter, as thegreater number of cylinders gives better torque-even turning effect--aswell as keeping down the weight--this latter because the biggercylinders must be more stoutly constructed than the small sizes; thisfact has led to the construction of engines having as many as eighteencylinders, arranged in three parallel rows in order to keep the lengthof crankshaft within reasonable limits. The aero engine of to-day may, roughly, be divided into four classes: these are the V type, in whichtwo rows of cylinders are set parallel at a certain angle to each other;the radial type, which consists of cylinders arranged radially andremaining stationary while the crankshaft revolves; the rotary, wherethe cylinders are disposed round a common centre and revolve rounda stationary shaft, and the vertical type, of four or sixcylinders--seldom more than this--arranged in one row. A modification ofthe V type is the eighteen-cylindered engine--the Sunbeam is one of thebest examples--in which three rows of cylinders are set parallel to eachother, working on a common crankshaft. The development these four typesstarted with that of the vertical--the simplest of all; the V, radial, and rotary types came after the vertical, in the order given. The evolution of the motor-car led to the adoption of the verticaltype of internal combustion engine in preference to any other, andit followed naturally that vertical engines should be first used foraeroplane propulsion, as by taking an engine that had been developed tosome extent, and adapting it to its new work, the problem of mechanicalflight was rendered easier than if a totally new type had had to beevolved. It was quickly realised--by the Wrights, in fact-that theminimum of weight per horse-power was the prime requirement for thesuccessful development of heavier-than-air machines, and at the sametime it was equally apparent that the utmost reliability had to beobtained from the engine, while a third requisite was economy, in orderto reduce the weight of petrol necessary for flight. Daimler, working steadily toward the improvement of the internalcombustion engine, had made considerable progress by the end oflast century. His two-cylinder engine of 1897 was approaching tothe present-day type, except as regards the method of ignition; thecylinders had 3. 55 inch diameter, with a 4. 75 inch piston stroke, and the engine was rated at 4. 5 brake horse-power, though it probablydeveloped more than this in actual running at its rated speed of 800revolutions per minute. Power was limited by the inlet and exhaustpassages, which, compared with present-day practice, were very small. The heavy castings of which the engine was made up are accounted for bythe necessity for considering foundry practice of the time, for in 1897castings were far below the present-day standard. The crank-case ofthis two-cylinder vertical Daimler engine was the only part made ofaluminium, and even with this no attempt was made to attain lightness, for a circular flange was cast at the bottom to form a stand for theengine during machining and erection. The general design can be followedfrom the sectional views, and these will show, too, that ignition was bymeans of a hot tube on the cylinder head, which had to be heated with ablow-lamp before starting the engine. With all its well known and hatedtroubles, at that time tube ignition had an advantage over the magneto, and the coil and accumulator system, in reliability; sparking plugs, too, were not so reliable then as they are now. Daimler fitted a verysimple type of carburettor to this engine, consisting only of a floatwith a single jet placed in the air passage. It may be said that thistwin-cylindered vertical was the first of the series from which has beenevolved the Mercedes-Daimler car and airship engines, built in sizes upto and even beyond 240 horse-power. In 1901 the development of the petrol engine was still so slight that itdid not admit of the construction, by any European maker, of an engineweighing less than 12 lbs. Per horse-power. Manly, working at theinstance of Professor Langley, produced a five-cylindered radial typeengine, in which both the design and workmanship showed a remarkableadvance in construction. At 950 revolutions per minute it developed 52. 4horse-power, weighing only 2. 4 pounds per horse-power; it was a veryremarkable achievement in engine design, considering the power developedin relation to the total weight, and it was, too, an interruption inthe development of the vertical type which showed that there were otherequally great possibilities in design. In England, the first vertical aero-engine of note was that designedby Green, the cylinder dimensions being 4. 15 inch diameter by 4. 75stroke--a fairly complete idea of this engine can be obtained from theaccompanying diagrams. At a speed of 1, 160 revolutions per minuteit developed 35 brake horse-power, and by accelerating up to 1, 220revolutions per minute a maximum of 40 brake horse-power could beobtained--the first-mentioned was the rated working speed of the enginefor continuous runs. A flywheel, weighing 23. 5 lbs. , was fitted to theengine, and this, together with the ignition system, brought the weightup to 188 lbs. , giving 5. 4 lbs. Per horse-power. In comparison with theengine fitted to the Wrights' aeroplane a greater power was obtainedfrom approximately the same cylinder volume, and an appreciable savingin weight had also been effected. The illustration shows the arrangementof the vertical valves at the top of the cylinder and the overhead camshaft, while the position of the carburettor and inlet pipes can bealso seen. The water jackets were formed by thin copper casings, eachcylinder being separate and having its independent jacket rigidlyfastened to the cylinder at the top only, thus allowing for freeexpansion of the casing; the joint at the bottom end was formed bysliding the jacket over a rubber ring. Each cylinder was bolted to thecrank-case and set out of line with the crankshaft, so that the crankhas passed over the upper dead centre by the time that the piston is atthe top of its stroke when receiving the full force of fuel explosion. The advantage of this desaxe setting is that the pressure in thecylinder acts on the crank-pin with a more effective leverage duringthat part of the stroke when that pressure is highest, and in additionthe side pressure of the piston on the cylinder wall, due to the thrustof the connecting rod, is reduced. Possibly the charging of the cylinderis also more complete by this arrangement, owing to the slower movementof the piston at the bottom of its stroke allowing time for an increasedcharge of mixture to enter the cylinder. A 60 horse-power engine was also made, having four vertical cylinders, each with a diameter of 5. 5 inches and stroke of 5. 75 inches, developingits rated power at 1, 100 revolutions per minute. By accelerating up to1, 200 revolutions per minute 70 brake horsepower could be obtained, anda maximum of 80 brake horse-power was actually attained with the type. The flywheel, fitted as with the original 35 horse-power engine, weighed37 lbs. ; with this and with the ignition system the total weight ofthe engine was only 250 lbs. , or 4. 2 lbs. Per horse-power at the normalrating. In this design, however, low weight in relation to power wasnot the ruling factor, for Green gave more attention to reliability andeconomy of fuel consumption, which latter was approximately 0. 6 pint ofpetrol per brake horse-power per hour. Both the oil for lubricatingthe bearings and the water for cooling the cylinders were circulated bypumps, and all parts of the valve gear, etc. , were completely enclosedfor protection from dust. A later development of the Green engine was a six-cylindered vertical, cylinder dimensions being 5. 5 inch diameter by 6 inch stroke, developing120 brake horsepower when running at 1, 250 revolutions per minute. Thetotal weight of the engine with ignition system 398 was 440 lbs. , or3. 66 lbs. Per horse-power. One of these engines was used on the machinewhich, in 1909, won the prize of L1, 000 for the first circular mileflight, and it may be noted, too, that S. F. Cody, making the circuitof England in 1911, used a four-cylinder Green engine. Again, it was aGreen engine that in 1914 won the L5, 000 prize offered for the best aeroengine in the Naval and Military aeroplane engine competition. Manufacture of the Green engines, in the period of the War, hadstandardised to the production of three types. Two of these weresix-cylinder models, giving respectively 100 and 150 brake horse-power, and the third was a twelve-cylindered model rated at 275 brakehorse-power. In 1910 J. S. Critchley compiled a list showing the types of engine thenbeing manufactured; twenty-two out of a total of seventy-six were of thefour-cylindered vertical type, and in addition to these there were twosix-cylindered verticals. The sizes of the four-cylinder types rangedfrom 26 up to 118 brake horse-power; fourteen of them developed lessthan 50 horse-power, and only two developed over 100 horse-power. It became apparent, even in the early stages of heavier-than-air flying, that four-cylinder engines did not produce the even torque that wasrequired for the rotation of the power shaft, even though a flywheelwas fitted to the engine. With this type of engine the breakage ofair-screws was of frequent occurrence, and an engine having a moreregular rotation was sought, both for this and to avoid the excessivevibration often experienced with the four-cylinder type. Another, pointthat forced itself on engine builders was that the increased power whichwas becoming necessary for the propulsion of aircraft made an increasein the number of cylinders essential, in order to obtain a light engine. An instance of the weight reduction obtainable in using six cylindersinstead of four is shown in Critchley's list, for one of thefour-cylinder engines developed 118. 5 brake horse-power and weighed1, 100 lbs. , whereas a six-cylinder engine by the same manufacturerdeveloped 117. 5 brake horse-power with a weight of 880 lbs. , therespective cylinder dimensions being 7. 48 diameter by 9. 06 strokefor the four-cylinder engine, and 6. 1 diameter by 7. 28 stroke for thesix-cylinder type. A list of aeroplane engines, prepared in 1912 by Graham Clark, showedthat, out of the total number of 112 engines then being manufactured, forty-two were of the vertical type, and of this number twenty-four hadfour-cylinders while sixteen were six-cylindered. The German aeroplaneengine trials were held a year later, and sixty-six engines entered thecompetition, fourteen of these being made with air-cooled cylinders. All of the ten engines that were chosen for the final trials were of thewater-cooled type, and the first place was won by a Benz four-cylindervertical engine which developed 102 brake horse-power at 1, 288revolutions per minute. The cylinder dimensions of this engine were 5. 1inch diameter by 7. 1 inch stroke, and the weight of the engine workedout at 3. 4 lbs. Per brake horse-power. During the trials the full-loadpetrol consumption was 0. 53 pint per horse-power per hour, and theamount of lubricating oil used was 0. 0385 pint per brake horse-power perhour. In general construction this Benz engine was somewhat similar tothe Green engine already described; the overhead valves, fitted in thetops of the cylinders, were similarly arranged, as was the cam-shaft;two springs were fitted to each of the valves to guard against thepossibility of the engine being put out of action by breakage of oneof the springs, and ignition was obtained by two high-tension magnetosgiving simultaneous sparks in each cylinder by means of two sparkingplugs--this dual ignition reduced the possibility of ignition troubles. The cylinder jackets were made of welded sheet steel so fitted aroundthe cylinder that the head was also water-cooled, and the jackets werecorrugated in the middle to admit of independent expansion. Even thelubrication system was duplicated, two sets of pumps being used, one tocirculate the main supply of lubricating oil, and the other to give acontinuous supply of fresh oil to the bearings, so that if thesupply from one pump failed the other could still maintain effectivelubrication. Development of the early Daimler type brought about the four-cylindervertical Mercedes-Daimler engine of 85 horse-power, with cylindersof 5. 5 diameter with 5. 9 inch stroke, the cylinders being cast in twopairs. The overhead arrangement of valves was adopted, and in laterdesigns push-rods were eliminated, the overhead cam-shaft being adoptedin their place. By 1914 the four-cylinder Mercedes-Daimler had beenpartially displaced from favour by a six-cylindered model, made in twosizes; the first of these gave a nominal brake horse-power of 80, havingcylinders of 4. 1 inches diameter by 5. 5 inches stroke; the second typedeveloped 100 horse-power with cylinders 4. 7 inches in diameter and 5. 5inches stroke, both types being run at 1, 200 revolutions per minute. Thecylinders of both these types were cast in pairs, and, instead of thewater jackets forming part of the casting, as in the design of theoriginal four-cylinder Mercedes-Daimler engine, they were made of steelwelded to flanges on the cylinders. Steel pistons, fitted with cast-ironrings, were used, and the overhead arrangement of valves and cam-shaftwas adopted. About 0. 55 pint per brake horse-power per hour was theusual fuel consumption necessary to full load running, and the enginewas also economical as regards the consumption of lubricating oil, the lubricating system being 'forced' for all parts, including thecam-shaft. The shape of these engines was very well suited for workwith aircraft, being narrow enough to admit of a streamline form beingobtained, while all the accessories could be so mounted as to producelittle or no wind resistance, and very little obstruction to the pilot'sview. The eight-cylinder Mercedes-Daimler engine, used for airship propulsionduring the War, developed 240 brake horse-power at 1, 100 revolutions perminute; the cylinder dimensions were 6. 88 diameter by 6. 5 stroke--oneof the instances in which the short stroke in relation to bore was verynoticeable. Other instances of successful vertical design-the types already detailedare fully sufficient to give particulars of the type generally--arethe Panhard, Chenu, Maybach, N. A. G. , Argus, Mulag, and the well-knownAustro-Daimler, which by 1917 was being copied in every combatantcountry. There are also the later Wright engines, and in Americathe Wisconsin six-cylinder vertical, weighing well under 4 lbs. Perhorse-power, is evidence of the progress made with this first type ofaero engine to develop. II. THE VEE TYPE An offshoot from the vertical type, doubling the power of this with onlya very slight--if any--increase in the length of crankshaft, the Veeor diagonal type of aero engine leaped to success through the insistentdemand for greater power. Although the design came after that of thevertical engine, by 1910, according to Critchley's list of aero engines, there were more Vee type engines being made than any other type, twenty-five sizes being given in the list, with an average rating of57. 4 brake horse-power. The arrangement of the cylinders in Vee form over the crankshaft, enabling the pistons of each pair of opposite cylinders to act upon thesame crank pin, permits of a very short, compact engine being built, andalso permits of reduction of the weight per horsepower, comparing thiswith that of the vertical type of engine, with one row of cylinders. Further, at the introduction of this type of engine it was seen thatcrankshaft vibration, an evil of the early vertical engines, waspractically eliminated, as was the want of longitudinal stiffness thatcharacterised the higher-powered vertical engines. Of the Vee type engines shown in Critchley's list in 1910 nineteendifferent sizes were constructed with eight cylinders, and withhorse-powers ranging from thirty to just over the hundred; the lightestof these weighed 2. 9 lbs. Per horse-power--a considerable advance indesign on the average vertical engine, in this respect of weight perhorse-power. There were also two sixteen-cylinder engines of Vee design, the larger of which developed 134 horse-power with a weight of only 2lbs. Per brake horse-power. Subsequent developments have indicated thatthis type, with the further development from it of the double-Vee, orengine with three rows of cylinders, is likely to become the standarddesign of aero engine where high powers are required. The constructionpermits of placing every part so that it is easy of access, and theform of the engine implies very little head resistance, while it can beplaced on the machine--supposing that machine to be of the single-enginetype--in such a way that the view of the pilot is very little obstructedwhile in flight. An even torque, or great uniformity of rotation, is transmitted to theair-screw by these engines, while the design also permits of such goodbalance of the engine itself that vibration is practically eliminated. The angle between the two rows of cylinders is varied according to thenumber of cylinders, in order to give working impulses at equal anglesof rotation and thus provide even torque; this angle is determined bydividing the number of degrees in a circle by the number of cylindersin either row of the engine. In an eight-cylindered Vee type engine, theangle between the cylinders is 90 degrees; if it is a twelve-cylinderedengine, the angle drops to 60 degrees. One of the earliest of the British-built Vee type engines was aneight-cylinder 50 horse-power by the Wolseley Company, constructed in1908 with a cylinder bore of 3. 75 inches and stroke of 5 inches, runningat a normal speed of 1, 350 revolutions per minute. With this engine, agearing was introduced to enable the propeller to run at a lower speedthan that of the engine, the slight loss of efficiency caused by thefriction of the gearing being compensated by the slower speed of theair-screw, which had higher efficiency than would have been the case ifit had been run at the engine speed. The ratio of the gearing--that is, the speed of the air-screw relatively to that of the engine, could bechosen so as to suit exactly the requirements of the air-screw, and thegearing itself, on this engine, was accomplished on the half-speed shaftactuating the valves. Very soon after this first design had been tried out, a second Vee typeengine was produced which, at 1, 200 revolutions per minute, developed 60horse-power; the size of this engine was practically identical with thatof its forerunner, the only exception being an increase of half an inchin the cylinder stroke--a very long stroke of piston in relation tothe bore of the cylinder. In the first of these two engines, which wasdesigned for airship propulsion, the weight had been about 8 lbs. Perbrake horse-power, no special attempt appearing to have been made tofine down for extreme lightness; in this 60 horse-power design, theweight was reduced to 6. 1 lbs. Per horse-power, counting the latteras normally rated; the engine actually gave a maximum of 75 brakehorse-power, reducing the ratio of weight to power very considerablybelow the figure given. The accompanying diagram illustrates a later Wolseley model, endelevation, the eight-cylindered 120 horse-power Vee type aero engineof the early war period. With this engine, each crank pin has twoconnecting rods bearing on it, these being placed side by side andconnected to the pistons of opposite cylinders and the two cylinders ofthe pair are staggered by an amount equal to the width of the connectingrod bearing, to afford accommodation for the rods. The crankshaft was anickel chrome steel forging, machined hollow, with four crank pins setat 180 degrees to each other, and carried in three bearings lined withanti-friction metal. The connecting rods were made of tubular nickelchrome steel, and the pistons of drawn steel, each being fitted withfour piston rings. Of these the two rings nearest to the piston headwere of the ordinary cast-iron type, while the others were of phosphorbronze, so arranged as to take the side thrust of the piston. Thecylinders were of steel, arranged in two groups or rows of four, theangular distance between them being 90 degrees. In the space above thecrankshaft, between the cylinder rows, was placed the valve-operatingmechanism, together with the carburettor and ignition system, thusrendering this a very compact and accessible engine. The combustionheads of the cylinders were made of cast-iron, screwed into the steelcylinder barrels; the water-jacket was of spun aluminium, with one endfitting over the combustion head and the other free to slide on thecylinder; the water-joint at the lower end was made tight by a Dermatinering carried between small flanges formed on the cylinder barrel. Overhead valves were adopted, and in order to make these as large aspossible the combustion chamber was made slightly larger in diameterthan the cylinder, and the valves set at an angle. Dual ignition wasfitted in each cylinder, coil and accumulator being used for startingand as a reserve in case of failure of the high-tension magneto systemfitted for normal running. There was a double set of lubricating pumps, ensuring continuity of the oil supply to all the bearings of the engine. The feature most noteworthy in connection with the running of this typeof engine was its flexibility; the normal output of power wasobtained with 1, 150 revolutions per minute of the crankshaft, but, byaccelerating up to 1, 400 revolutions, a maximum of 147 brake horse-powercould be obtained. The weight was about 5 lbs. Per horse-power, thecylinder dimensions being 5 inches bore by 7 inches stroke. Economy inrunning was obtained, the fuel consumption being 0. 58 pint per brakehorse-power per hour at full load, with an expenditure of about 0. 075pint of lubricating oil per brake horse-power per hour. Another Wolseley Vee type that was standardised was a 90 horse-powereight-cylinder engine running at 1, 800 revolutions per minute, witha reducing gear introduced by fitting the air screw on the half-speedshaft. First made semi-cooled--the exhaust valve was left air-cooled, and then entirely water-jacketed--this engine demonstrated the advantageof full water cooling, for under the latter condition the same power wasdeveloped with cylinders a quarter of an inch less in diameter than inthe semi-cooled pattern; at the same time the weight was brought down to4 1/2 lbs. Per horsepower. A different but equally efficient type of Vee design was the Dormanengine, of which an end elevation is shown; this developed 80 brakehorse-power at a speed of 1, 300 revolutions per minute, with a cylinderbore of 5 inches; each cylinder was made in cast-iron in one piece withthe combustion chamber, the barrel only being water-jacketed. Auxiliaryexhaust ports were adopted, the holes through the cylinder wall beinguncovered by the piston at the bottom of its stroke--the piston, 4. 75inches in length, was longer than its stroke, so that these ports werecovered when it was at the top of the cylinder. The exhaust dischargedthrough the ports into a belt surrounding the cylinder, the belts on thecylinders being connected so that the exhaust gases were taken througha single pipe. The air was drawn through the crank case, before reachingthe carburettor, this having the effect of cooling the oil in the crankcase as well as warming the air and thus assisting in vaporising thepetrol for each charge of the cylinders. The inlet and exhaust valveswere of the overhead type, as may be gathered from the diagram, and inspite of cast-iron cylinders being employed a light design was obtained, the total weight with radiator, piping, and water being only 5. 5 lbs. Per horse-power. Here was the antithesis of the Wolseley type in the matter of bore inrelation to stroke; from about 1907 up to the beginning of the war, andeven later, there was controversy as to which type--that in which thebore exceeded the stroke, or vice versa--gave greater efficiency. The short-stroke enthusiasts pointed to the high piston speed of thelong-stroke type, while those who favoured the latter design contendedthat full power could not be obtained from each explosion in theshort-stroke type of cylinder. It is now generally conceded that thelong-stroke engine yields higher efficiency, and in addition to this, so far as car engines are concerned, the method of rating horse-powerin relation to bore without taking stroke into account has given thelong-stroke engine an advantage, actual horse-power with a long strokeengine being in excess of the nominal rating. This may have had someinfluence on aero engine design, but, however this may have been, thelong-stroke engine has gradually come to favour, and its rival has takensecond place. For some time pride of place among British Vee type engines was heldby the Sunbeam Company, which, owing to the genius of Louis Coatalen, together with the very high standard of construction maintained by thefirm, achieved records and fame in the middle and later periods of thewar. Their 225 horse-power twelve-cylinder engine ran at a normalspeed of 2, 000 revolutions per minute; the air screw was driven throughgearing at half this speed, its shaft being separate from the timinggear and carried in ball-bearings on the nose-piece of the engine. Thecylinders were of cast-iron, entirely water-cooled; a thin casing formedthe water-jacket, and a very light design was obtained, the weight beingonly 3. 2 lbs. Per horse-power. The first engine of Sunbeam design hadeight cylinders and developed 150 horse-power at 2, 000 revolutionsper minute; the final type of Vee design produced during the war wastwelve-cylindered, and yielded 310 horse-power with cylinders 4. 3 inchesbore by 6. 4 inches stroke. Evidence in favour of the long-stroke engineis afforded in this type as regards economy of working; under full load, working at 2, 000 revolutions per minute, the consumption was 0. 55 pintsof fuel per brake horse-power per hour, which seems to indicate that thelong stroke permitted of full use being made of the power resulting fromeach explosion, in spite of the high rate of speed of the piston. Developing from the Vee type, the eighteen-cylinder 475 brakehorse-power engine, designed during the war, represented for a timethe limit of power obtainable from a single plant. It was water-cooledthroughout, and the ignition to each cylinder was duplicated; thisengine proved fully efficient, and economical in fuel consumption. It was largely used for seaplane work, where reliability was fully asnecessary as high power. The abnormal needs of the war period brought many British firms into theranks of Vee-type engine-builders, and, apart from those mentioned, the most notable types produced are the Rolls-Royce and the Napier. The first mentioned of these firms, previous to 1914 had concentratedentirely on car engines, and their very high standard of production inthis department of internal combustion engine work led, once they tookup the making of aero engines, to extreme efficiency both of design andworkmanship. The first experimental aero engine, of what became knownas the 'Eagle' type, was of Vee design--it was completed in Marchof 1915--and was so successful that it was standardised for quantityproduction. How far the original was from the perfection subsequentlyascertained is shown by the steady increase in developed horse-powerof the type; originally designed to develop 200 horse-power, it wasdeveloped and improved before its first practical trial in October of1915, when it developed 255 horsepower on a brake test. Researchand experiment produced still further improvements, for, without anyenlargement of the dimensions, or radical alteration in design, thepower of the engine was brought up to 266 horse-power by March of 1916, the rate of revolutions of 1, 800 per minute being maintained throughout. July, 1916 gave 284 horse-power; by the cud of the year this had beenincreased to 322 horse-power; by September of 1917 the increase was to350 horse-power, and by February of 1918 then 'Eagle' type of engine wasrated at 360 horse-power, at which standard it stayed. But there is nomore remarkable development in engine design than this, a 75 per centincrease of power in the same engine in a period of less than threeyears. To meet the demand for a smaller type of engine for use on trainingmachines, the Rolls-Royce firm produced the 'Hawk' Vee-type engine of100 horsepower, and, intermediately between this and the 'Eagle, ' the'Falcon' engine came to being with an original rated horse-power of 205at 1, 800 revolutions per minute, in April of 1916. Here was another caseof growth of power in the same engine through research, almost similarto that of the 'Eagle' type, for by July of 1918 the 'Falcon' wasdeveloping 285 horse-power with no radical alteration of design. Finally, in response to the constant demand for increase of power in asingle plant, the Rolls-Royce company designed and produced the 'Condor'type of engine, which yielded 600 horse-power on its first test inAugust of 1918. The cessation of hostilities and consequent falling offin the demand for extremely high-powered plants prevented the 'Condor'being developed to its limit, as had been the 'Falcon' and 'Eagle'types. The 'Eagle 'engine was fitted to the two Handley-Page aeroplanes--whichmade flights from England to India--it was virtually standard on theHandley-Page bombers of the later War period, though to a certain extentthe American 'Liberty' engine was also used. Its chief record, however, is that of being the type fitted to the Vickers-Vimy aeroplane whichmade the first Atlantic flight, covering the distance of 1, 880 miles ata speed averaging 117 miles an hour. The Napier Company specialised on one type of engine from the outset, a power plant which became known as the 'Lion' engine, giving 450horse-power with twelve cylinders arranged in three rows of four each. Considering the engine as 'dry, ' or without fuel and accessories, anabnormally light weight per horse-power--only 1. 89 lbs. --was attainedwhen running at the normal rate of revolution. The cylinders andwater-jackets are of steel, and there is fitted a detachable aluminiumcylinder head containing inlet and exhaust valves and valve actuatingmechanism; pistons are of aluminium alloy, and there are two inlet andtwo exhaust valves to each cylinder, the whole of the valve mechanismbeing enclosed in an oil-tight aluminium case. Connecting rods andcrankshaft are of steel, the latter being machined from a solid steelforging and carried in five roller bearings and one plain bearing at theforward end. The front end of the crank-case encloses reduction gear forthe propeller shaft, together with the shaft and bearings. There aretwo suction and one pressure type oil pumps driven through gears athalf-engine speed, and two 12 spark magnetos, giving 2 sparks in eachcylinder. The cylinders are set with the central row vertical, and the two siderows at angles of 60 degrees each; cylinder bore is 5 1/2 inches, andstroke 5 1/8 inches; the normal rate of revolution is 1, 350 per minute, and the reducing gear gives one revolution of the propeller shaft to1. 52 revolutions of crankshaft. Fuel consumption is 0. 48lbs. Of fuel perbrake horse-power hour at full load, and oil consumption is 0. 020 lbs. Per brake horsepower hour. The dry weight of the engine, complete withpropeller boss, carburettors, and induction pipes, is 850 lbs. , and thegross weight in running order, with fuel and oil for six hours working, is 2, 671 lbs. , exclusive of cooling water. To this engine belongs an altitude record of 30, 500 feet, made atMartlesham, near Ipswich, on January 2nd, 1919, by Captain Lang, R. A. F. , the climb being accomplished in 66 minutes 15 seconds. Previous to this, the altitude record was held by an Italian pilot, who made 25, 800 feetin an hour and 57 minutes in 1916. Lang's climb was stopped throughthe pressure of air, at the altitude he reached, being insufficient fordriving the small propellers on the machine which worked the petrol andoil pumps, or he might have made the height said to have been attainedby Major Schroeder on February 27th, 1920, at Dayton, Ohio. Schroederis said to have reached an altitude of 36, 020 feet on a Napier biplane, and, owing to failure of the oxygen supply, to have lost consciousness, fallen five miles, righted his machine when 2, 000 feet in the air, andalighted successfully. Major Schroeder is an American. Turning back a little, and considering other than British design of Veeand double-Vee or 'Broad arrow' type of engine, the Renault firm fromthe earliest days devoted considerable attention to the development ofthis type, their air-cooled engines having been notable examples fromthe earliest days of heavier-than-air machines. In 1910 they were makingthree sizes of eight-cylindered Vee-type engines, and by 1915 they hadincreased to the manufacture of five sizes, ranging from 25 to 100 brakehorse-power, the largest of the five sizes having twelve cylinders butstill retaining the air-cooled principle. The De Dion firm, also, made Vee-type engines in 1914, being represented by an 80 horse-powereight-cylindered engine, air-cooled, and a 150 horse-power, alsoof eight cylinders, water-cooled, running at a normal rate of 1, 600revolutions per minute. Another notable example of French constructionwas the Panhard and Levassor 100 horse-power eight-cylinder Vee engine, developing its rated power at 1, 500 revolutions per minute, and havingthe--for that time--low weight of 4. 4 lbs. Per horse-power. American Vee design has followed the British fairly cclosely; theCurtiss Company produced originally a 75 horse-power eight-cylinder Veetype running at 1, 200 revolutions per minute, supplementing this witha 170 horse-power engine running at 1, 600 revolutions per minute, andlater with a twelve-cylinder model Vee type, developing 300 horse-powerat 1, 500 revolutions per minute, with cylinder bore of 5 inches andstroke of 7 inches. An exceptional type of American design was the KempVee engine of 80 horse-power in which the cylinders were cooled by acurrent of air obtained from a fan at the forward end of the engine. With cylinders of 4. 25 inches bore and 4. 75 inches stroke, the raterpower was developed at 1, 150 revolutions per minute, and with the enginecomplete the weight was only 4. 75 lbs. Per horse-power. III. THE RADIAL TYPE The very first successful design of internal combustion aero engine madewas that of Charles Manly, who built a five-cylinder radial engine in1901 for use with Langley's 'aerodrome, ' as the latter inventor decidedto call what has since become known as the aeroplane. Manly made anumber of experiments, and finally decided on radial design, in whichthe cylinders are so rayed round a central crank-pin that the pistonsact successively upon it; by this arrangement a very short and compactengine is obtained, with a minimum of weight, and a regular crankshaftrotation and perfect balance of inertia forces. When Manly designed his radial engine, high speed internal combustionengines were in their infancy, and the difficulties in constructioncan be partly realised when the lack of manufacturing methods for thishigh-class engine work, and the lack of experimental data on the variousmaterials, are taken into account. During its tests, Manly's enginedeveloped 52. 4 brake horsepower at a speed of 950 revolutions perminute, with the remarkably low weight of only 2. 4 lbs. Per horsepower;this latter was increased to 3. 6 lbs. When the engine was completedby the addition of ignition system, radiator, petrol tank, and allaccessories, together with the cooling water for the cylinders. In Manly's engine, the cylinders were of steel, machined outside andinside to 1/16 of an inch thickness; on the side of cylinder, at the topend, the valve chamber was brazed, being machined from a solid forging, The casing which formed the water-jacket was of sheet steel, 1/50 of aninch in thickness, and this also was brazed on the cylinder and tothe valve chamber. Automatic inlet valves were fitted, and the exhaustvalves were operated by a cam which had two points, 180 degreesapart; the cam was rotated in the opposite direction to the engine atone-quarter engine speed. Ignition was obtained by using a one-sparkcoil and vibrator for all cylinders, with a distributor to selectthe right cylinder for each spark--this was before the days of thehigh-tension magneto and the almost perfect ignition systems that makersnow employ. The scheme of ignition for this engine was originated byManly himself, and he also designed the sparking plugs fitted in thetops of the cylinders. Through fear of trouble resulting if the steelpistons worked on the steel cylinders, cast iron liners were introducedin the latter, 1/16 of an inch thick. The connecting rods of this engine were of virtually the same type as isemployed on nearly all modern radial engines. The rod for one cylinderhad a bearing along the whole of the crank pin, and its end enclosed thepin; the other four rods had bearings upon the end of the first rod, and did not touch the crank pin. The accompanying diagram shows thisconstruction, together with the means employed for securing the ends ofthe four rods--the collars were placed in position after the rods hadbeen put on. The bearings of these rods did not receive any of therubbing effect due to the rotation of the crank pin, the rubbing on thembeing only that of the small angular displacement of the rods duringeach revolution; thus there was no difficulty experienced with thelubrication. Another early example of the radial type of engine was the FrenchAnzani, of which type one was fitted to the machine with which Bleriotfirst crossed the English Channel--this was of 25 horse-power. Theearliest Anzani engines were of the three-cylinder fan type, onecylinder being vertical, and the other two placed at an angle of 72degrees on each side, as the possibility of over-lubrication of thebottom cylinders was feared if a regular radial construction wereadopted. In order to overcome the unequal balance of this type, balanceweights were fitted inside the crank case. The final development of this three-cylinder radial was the 'Y' type ofengine, in which the cylinders were regularly disposed at 120 degreesapart, the bore was 4. 1, stroke 4. 7 inches, and the power developed was30 brake horse-power at 1, 300 revolutions per minute. Critchley's list of aero engines being constructed in 1910 shows twelveof the radial type, with powers of between 14 and 100 horse-power, andwith from three to ten cylinder--this last is probably the greatestnumber of cylinders that can be successfully arranged in circular form. Of the twelve types of 1910, only two were water-cooled, and it is to benoted that these two ran at the slowest speeds and had the lowest weightper horse-power of any. The Anzani radial was considerably developed special attention beingpaid to this type by its makers and by 1914 the Anzani list comprisedseven different sizes of air-cooled radials. Of these the largest hadtwenty cylinders, developing 200 brake horse-power--it was virtuallya double radial--and the smallest was the original 30 horse-powerthree-cylinder design. A six-cylinder model was formed by a combinationof two groups of three cylinders each, acting upon a double-throwcrankshaft; the two crank pins were set at 180 degrees to each other, and the cylinder groups were staggered by an amount equal to thedistance between the centres of the crank pins. Ten-cylinder radialengines are made with two groups of five cylinders acting upon twocrank pins set at 180 degrees to each other, the largest Anzani 'ten'developed 125 horsepower at 1, 200 revolutions per minute, the tencylinders being each 4. 5 inches in bore with stroke of 5. 9 inches, andthe weight of the engine being 3. 7 lbs. Per horse-power. In the 200horse-power Anzani radial the cylinders are arranged in four groups offive each, acting on two crank pins. The bore of the cylinders in thisengine is the same as in the three-cylinder, but the stroke is increasedto 5. 5 inches. The rated power is developed at 1, 300 revolutions perminute, and the engine complete weighs 3. 4 lbs. Per horse-power. With this 200 horse-power Anzani, a petrol consumption of as low as 0. 49lbs. Of fuel per brake horse-power per hour has been obtained, butthe consumption of lubricating oil is compensatingly high, being up toone-fifth of the fuel used. The cylinders are set desaxe with thecrank shaft, and are of cast-iron, provided with radiating ribs forair-cooling; they are attached to the crank case by long bolts passingthrough bosses at the top of the cylinders, and connected to other boltsat right angles through the crank case. The tops of the cylinders areformed flat, and seats for the inlet and exhaust valves are formed onthem. The pistons are cast-iron, fitted with ordinary cast-iron springrings. An aluminium crank case is used, being made in two halvesconnected together by bolts, which latter also attach the engine to theframe of the machine. The crankshaft is of nickel steel, made hollow, and mounted on ball-bearings in such a manner that practically acombination of ball and plain bearings is obtained; the central webof the shaft is bent to bring the centres of the crank pins as closetogether as possible, leaving only room for the connecting rods, andthe pins are 180 degrees apart. Nickel steel valves of the cone-seated, poppet type are fitted, the inlet valves being automatic, and those forthe exhaust cam-operated by means of push-rods. With an engine havingsuch a number of cylinders a very uniform rotation of the crankshaft isobtained, and in actual running there are always five of the cylindersgiving impulses to the crankshaft at the same time. An interesting type of pioneer radial engine was the Farcot, in whichthe cylinders were arranged in a horizontal plane, with a verticalcrankshaft which operated the air-screw through bevel gearing. This wasan eight-cylinder engine, developing 64 horse-power at 1, 200 revolutionsper minute. The R. E. P. Type, in the early days, was a 'fan' engine, but the designer, M. Robert Pelterie, turned from this design to aseven-cylinder radial, which at 1, 100 revolutions per minute gave 95horse-power. Several makers entered into radial engine development inthe years immediately preceding the War, and in 1914 there weresome twenty-two different sizes and types, ranging from 30 to 600horse-power, being made, according to report; the actual construction ofthe latter size at this time, however, is doubtful. Probably the best example of radial construction up to the outbreak ofWar was the Salmson (Canton-Unne) water-cooled, of which in 1914six sizes were listed as available. Of these the smallest was aseven-cylinder 90 horse-power engine, and the largest, rated at 600horse-power, had eighteen cylinders. These engines, during the War, weremade under license by the Dudbridge Ironworks in Great Britain. The accompanying diagram shows the construction of the cylinders in the200 horse-power size, showing the method of cooling, and the arrangementof the connecting rods. A patent planetary gear, also shown in thediagram, gives exactly the same stroke to all the pistons. The completeengine has fourteen cylinders, of forged steel machined all over, andso secured to the crank case that any one can be removed without partingthe crank case. The water-jackets are of spun copper, brazed on to thecylinder, and corrugated so as to admit of free expansion; the water iscirculated by means of a centrifugal pump. The pistons are of cast-iron, each fitted with three rings, and the connecting rods are of high gradesteel, machined all over and fitted with bushes of phosphor bronze;these rods are connected to a central collar, carried on the crank pinby two ball-bearings. The crankshaft has a single throw, and is madein two parts to allow the cage for carrying the big end-pins of theconnecting rods to be placed in position. The casing is in two parts, on one of which the brackets for fixing theengine are carried, while the other part carries the valve-gear. Boltssecure the two parts together. The mechanically-operated steel valveson the cylinders are each fitted with double springs and the valves areoperated by rods and levers. Two Zenith carburettors are fitted on therear half of the crank case, and short induction pipes are led to eachcylinder; each of the carburettors is heated by the exhaust gases. Ignition is by two high-tension magnetos, and a compressed airself-starting arrangement is provided. Two oil pumps are fitted forlubricating purposes, one of which forces oil to the crankshaft andconnecting-rod bearings, while the second forces oil to the valve gear, the cylinders being so arranged that the oil which flows along the wallscannot flood the lower cylinders. This engine operates upon a six-strokecycle, a rather rare arrangement for internal combustion engines of theelectrical ignition type; this is done in order to obtain equal angularintervals for the working impulses imparted to the rotating crankshaft, as the cylinders are arranged in groups of seven, and all act upon theone crankshaft. The angle, therefore, between the impulses is 77 1/7degrees. A diagram is inset giving a side view of the engine, in orderto show the grouping of the cylinders. The 600 horse-power Salmson engine was designed with a view to fittingto airships, and was in reality two nine-cylindered engines, with agear-box connecting them; double air-screws were fitted, and these wereso arranged that either or both of them might be driven by either orboth engines; in addition to this, the two engines were complete andseparate engines as regards carburation and ignition, etc. , so thatthey could be run independently of each other. The cylinders wereexceptionally 'long stroke, ' being 5. 9 inches bore to 8. 27 inchesstroke, and the rated power was developed at 1, 200 revolutions perminute, the weight of the complete engine being only 4. 1 lbs. Perhorse-power at the normal rating. A type of engine specially devised for airship propulsion is that inwhich the cylinders are arranged horizontally instead of vertically, themain advantages of this form being the reduction of head resistance andless obstruction to the view of the pilot. A casing, mounted on the topof the engine, supports the air-screw, which is driven through bevelgearing from the upper end of the crankshaft. With this type of enginea better rate of air-screw efficiency is obtained by gearing the screwdown to half the rate of revolution of the engine, this giving a moreeven torque. The petrol consumption of the type is very low, being only0. 48 lbs. Per horse-power per hour, and equal economy is claimed asregards lubricating oil, a consumption of as little as 0. 04 lbs. Perhorse-power per hour being claimed. Certain American radial engines were made previous to 1914, theprincipal being the Albatross six-cylinder engines of 50 and 100horse-powers. Of these the smaller size was air-cooled, with cylindersof 4. 5 inches bore and 5 inches stroke, developing the rated powerat 1, 230 revolutions per minute, with a weight of about 5 lbs. Perhorse-power. The 100 horse-power size had cylinders of 5. 5 inches bore, developing its rated power at 1, 230 revolutions per minute, and weighingonly 2. 75 lbs. Per horse-power. This engine was markedly similar to thesix-cylindered Anzani, having all the valves mechanically operated, andwith auxiliary exhaust ports at the bottoms of the cylinders, overrunby long pistons. These Albatross engines had their cylinders arranged intwo groups of three, with each group of three pistons operating on oneof two crank pins, each 180 degrees apart. The radial type of engine, thanks to Charles Manly, had the honour ofbeing first in the field as regards aero work. Its many advantages, among which may be specially noted the very short crankshaft as comparedwith vertical, Vee, or 'broad arrow' type of engine, and consequentgreater rigidity, ensure it consideration by designers of to-day, andrender it certain that the type will endure. Enthusiasts claim that the'broad arrow' type, or Vee with a third row of cylinders inset betweenthe original two, is just as much a development from the radial engineas from the vertical and resulting Vee; however this may be, there isa place for the radial type in air-work for as long as the internalcombustion engine remains as a power plant. IV. THE ROTARY TYPE M. Laurent Seguin, the inventor of the Gnome rotary aero engine, provided as great a stimulus to aviation as any that was given anteriorto the war period, and brought about a great advance in mechanicalflight, since these well-made engines gave a high-power output for theirweight, and were extremely smooth in running. In the rotary design thecrankshaft of the engine is stationary, and the cylinders, crankcase, and all their adherent parts rotate; the working is thus exactlyopposite in principle to that of the radial type of aero engine, andthe advantage of the rotary lies in the considerable flywheel effectproduced by the revolving cylinders, with consequent evenness of torque. Another advantage is that air-cooling, adopted in all the Gnome engines, is rendered much more effective by the rotation of the cylinders, thoughthere is a tendency to distortion through the leading side of eachcylinder being more efficiently cooled than the opposite side; advocatesof other types are prone to claim that the air resistance to therevolving cylinders absorbs some 10 per cent of the power developed bythe rotary engine, but that has not prevented the rotary from attainingto great popularity as a prime mover. There were, in the list of aero engines compiled in 1910, five rotaryengines included, all air-cooled. Three of these were Gnome engines, andtwo of the make known as 'International. ' They ranged from 21. 5 to 123horse-power, the latter being rated at only 1. 8 lbs. Weight per brakehorse-power, and having fourteen cylinders, 4. 33 inches in diameterby 4. 7 inches stroke. By 1914 forty-three different sizes and typesof rotary engine were being constructed, and in 1913 five rotary typeengines were entered for the series of aeroplane engine trials heldin Germany. Minor defects ruled out four of these, and only theGerman Bayerischer Motoren Flugzeugwerke completed the seven-hour testprescribed for competing engines. Its large fuel consumption barred thisengine from the final trials, the consumption being some 0. 95 pintsper horse-power per hour. The consumption of lubricating oil, also wasexcessive, standing at 0. 123 pint per horse-power per hour. The enginegave 37. 5 effective horse-power during its trial, and the loss due toair resistance was 4. 6 horse-power, about 11 per cent. The accompanyingdrawing shows the construction of the engine, in which the sevencylinders are arranged radially on the crank case; the method ofconnecting the pistons to the crank pins can be seen. The mixture isdrawn through the crank chamber, and to enter the cylinder it passesthrough the two automatic valves in the crown of the piston; the exhaustvalves are situated in the tops of the cylinders, and are actuated bycams and push-rods. Cooling of the cylinder is assisted by the radialrings, and the diameter of these rings is increased round the hottestpart of the cylinder. When long flights are undertaken the advantage ofthe light weight of this engine is more than counterbalanced by its highfuel and lubricating oil consumption, but there are other makes whichare much better than this seven-cylinder German in respect of this. Rotation of the cylinders in engines of this type is produced by theside pressure of the pistons on the cylinder walls, and in order toprevent this pressure from becoming abnormally large it is necessaryto keep the weight of the piston as low as possible, as the pressure isproduced by the tangential acceleration and retardation of the piston. On the upward stroke the circumferential velocity of the piston israpidly increased, which causes it to exert a considerable tangentialpressure on the side of the cylinder, and on the return stroke thereis a corresponding retarding effect due to the reduction of thecircumferential velocity of the piston. These side pressures cause anappreciable increase in the temperatures of the cylinders and pistons, which makes it necessary to keep the power rating of the engines fairlylow. Seguin designed his first Gnome rotary as a 34 horse-power engine whenrun at a speed of 1, 300 revolutions per minute. It had five cylinders, and the weight was 3. 9 lbs. Per horse-power. A seven-cylinder model soondisplaced this first engine, and this latter, with a total weight of 165lbs. , gave 61. 5 horse-power. The cylinders were machined out of solidnickel chrome-steel ingots, and the machining was carried out so thatthe cylinder walls were under 1/6 of an inch in thickness. The pistonswere cast-iron, fitted each with two rings, and the automatic inletvalve to the cylinder was placed in the crown of the piston. Theconnecting rods, of 'H' section, were of nickel chrome-steel, and thelarge end of one rod, known as the 'master-rod' embraced the crank pin;on the end of this rod six hollow steel pins were carried, and to thesethe remaining six connecting-rods were attached. The crankshaft of theengine was made of nickel chrome-steel, and was in two parts connectedtogether at the crank pin; these two parts, after the master-rod hadbeen placed in position and the other connecting rods had been attachedto it, were firmly secured. The steel crank case was made in five parts, the two central ones holding the cylinders in place, and on one sideanother of the five castings formed a cam-box, to the outside of whichwas secured the extension to which the air-screw was attached. On theother side of the crank case another casting carried the thrust-box, andthe whole crank case, with its cylinders and gear, was carried on thefixed crank shaft by means of four ball-bearings, one of which also tookthe axial thrust of the air-screw. For these engines, castor oil is the lubricant usually adopted, and itis pumped to the crankshaft by means of a gear-driven oil pump; fromthis shaft the other parts of the engine are lubricated by means ofcentrifugal force, and in actual practice sufficient unburnt oil passesthrough the cylinders to lubricate the exhaust valve, which partlyaccounts for the high rate of consumption of lubricating oil. A verysimple carburettor of the float less, single-spray type was used, andthe mixture was passed along the hollow crankshaft to the interior ofthe crank case, thence through the automatic inlet valves in the tops ofthe pistons to the combustion chambers of the cylinders. Ignition wasby means of a high-tension magneto specially geared to give the correcttiming, and the working impulses occurred at equal angular intervals of102. 85 degrees. The ignition was timed so that the firing spark occurredwhen the cylinder was 26 degrees before the position in which the pistonwas at the outer end of its stroke, and this timing gave a maximumpressure in the cylinder just after the piston had passed this position. By 1913, eight different sizes of the Gnome engine were beingconstructed, ranging from 45 to 180 brake horse-power; four of thesewere single-crank engines one having nine and the other three havingseven cylinders. The remaining four were constructed with two cranks;three of them had fourteen cylinders apiece, ranged in groups of seven, acting on the cranks, and the one other had eighteen cylinders ranged intwo groups of nine, acting on its two cranks. Cylinders of the two-crankengines are so arranged (in the fourteen-cylinder type) that fourteenequal angular impulses occur during each cycle; these engines aresupported on bearings on both sides of the engine, the air-screw beingplaced outside the front support. In the eighteen-cylinder model theimpulses occur at each 40 degrees of angular rotation of the cylinders, securing an extremely even rotation of the air-screw. In 1913 the Gnome Monosoupape engine was introduced, a model in whichthe inlet valve to the cylinder was omitted, while the piston was of theordinary cast-iron type. A single exhaust valve in the cylinder head wasoperated in a manner similar to that on the previous Gnome engines, andthe fact of this being the only valve on the cylinder gave the engineits name. Each cylinder contained ports at the bottom which communicatedwith the crank chamber, and were overrun by the piston when this wasapproaching the bottom end of its stroke. During the working cycle ofthe engine the exhaust valve was opened early to allow the exhaust gasesto escape from the cylinder, so that by the time the piston overran theports at the bottom the pressure within the cylinder was approximatelyequal to that in the crank case, and practically no flow of gas tookplace in either direction through the ports. The exhaust valve remainedopen as usual during the succeeding up-stroke of the piston, andthe valve was held open until the piston had returned through aboutone-third of its downward stroke, thus permitting fresh air to enter thecylinder. The exhaust valve then closed, and the downward motion of thepiston, continuing, caused a partial vacuum inside the cylinder; whenthe piston overran the ports, the rich mixture from the crank caseimmediately entered. The cylinder was then full of the mixture, and thenext upward stroke of the piston compressed the charge; upon ignitionthe working cycle was repeated. The speed variation of this enginewas obtained by varying the extent and duration of the opening of theexhaust valves, and was controlled by the pilot by hand-operated leversacting on the valve tappet rollers. The weight per horsepower of theseengines was slightly less than that of the two-valve type, while thelubrication of the gudgeon pin and piston showed an improvement, so thata lower lubricating oil consumption was obtained. The 100 horse-powerGnome Monosoupape was built with nine cylinders, each 4. 33 inchesbore by 5. 9 inches stroke, and it developed its rated power at 1, 200revolutions per minute. An engine of the rotary type, almost as well known as the Gnome, is theClerget, in which both cylinders and crank case are made of steel, theformer having the usual radial fins for cooling. In this type theinlet and exhaust valves are both located in the cylinder head, andmechanically operated by push-rods and rockers. Pipes are carried fromthe crank case to the inlet valve casings to convey the mixture to thecylinders, a carburettor of the central needle type being used. Thecarburetted mixture is taken into the crank case chamber in a mannersimilar to that of the Gnome engine. Pistons of aluminium alloy, withthree cast-iron rings, are fitted, the top ring being of the obturatortype. The large end of one of the nine connecting rods embraces thecrank pin and the pressure is taken on two ball-bearings housed in theend of the rod. This carries eight pins, to which the other rods areattached, and the main rod being rigid between the crank pin and pistonpin determines the position of the pistons. Hollow connecting-rodsare used, and the lubricating oil for the piston pins passes from thecrankshaft through the centres of the rods. Inlet and exhaust valvescan be set quite independently of one another--a useful point, sincethe correct timing of the opening of these valves is of importance. Theinlet valve opens 4 degrees from top centre and closes after the bottomdead centre of the piston; the exhaust valve opens 68 degrees beforethe bottom centre and closes 4 degrees after the top dead centre of thepiston. The magnetos are set to give the spark in the cylinder at 25degrees before the end of the compression stroke--two high-tensionmagnetos are used: if desired, the second one can be adjusted to givea later spark for assisting the starting of the engine. The lubricatingoil pump is of the valveless two-plunger type, so geared that it runsat seven revolutions to 100 revolutions of the engine; by countingthe pulsations the speed of the engine can be quickly calculated bymultiplying the pulsations by 100 and dividing by seven. In the 115horse-power nine-cylinder Clerget the cylinders are 4. 7 bore with a 6. 3inches stroke, and the rated power of the engine is obtained at1, 200 revolutions per minute. The petrol consumption is 0. 75 pint perhorse-power per hour. A third rotary aero engine, equally well known with the foregoing two, is the Le Rhone, made in four different sizes with power outputs of from50 to 160 horse-power; the two smaller sizes are single crank engineswith seven and nine cylinders respectively, and the larger sizes areof double-crank design, being merely the two smaller sizesdoubled--fourteen and eighteen-cylinder engines. The inlet andexhaust valves are located in the cylinder head, and both valves aremechanically operated by one push-rod and rocker, radial pipes fromcrank case to inlet valve casing taking the mixture to the cylinders. The exhaust valves are placed on the leading, or air-screw side, of theengine, in order to get the fullest possible cooling effect. The ratedpower of each type of engine is obtained at 1, 200 revolutions perminute, and for all four sizes the cylinder bore is 4. 13 inches, witha 5. 5 inches piston stroke. Thin cast-iron liners are shrunk intothe steel cylinders in order to reduce the amount of piston friction. Although the Le Rhone engines are constructed practically throughoutof steel, the weight is only 2. 9 lbs. Per horse-power in theeighteen-cylinder type. American enterprise in the construction of the rotary type is perhapsbest illustrated in the 'Gyro 'engine; this was first constructed withinlet valves in the heads of the pistons, after the Gnome pattern, theexhaust valves being in the heads of the cylinders. The inlet valve inthe crown of each piston was mechanically operated in a very ingeniousmanner by the oscillation of the connecting-rod. The Gyro-Duplex enginesuperseded this original design, and a small cross-section illustrationof this is appended. It is constructed in seven and nine-cylinder sizes, with a power range of from 50 to 100 horse-power; with the largest sizethe low weight of 2. 5 lbs.. Per horse-power is reached. The design isof considerable interest to the internal combustion engineer, for itembodies a piston valve for controlling auxiliary exhaust ports, whichalso acts as the inlet valve to the cylinder. The piston uncovers theauxiliary ports when it reaches the bottom of its stroke, and at the endof the power stroke the piston is in such a position that the exhaustcan escape over the top of it. The exhaust valve in the cylinder head isthen opened by means of the push-rod and rocker, and is held open untilthe piston has completed its upward stroke and returned through morethan half its subsequent return stroke. When the exhaust valve closes, the cylinder has a charge of fresh air, drawn in through the exhaustvalve, and the further motion of the piston causes a partial vacuum;by the time the piston reaches bottom dead centre the piston-valve hasmoved up to give communication between the cylinder and the crank case, therefore the mixture is drawn into the cylinder. Both the piston valveand exhaust valve are operated by cams formed on the one casting, whichrotates at seven-eighths engine speed for the seven-cylinder type, andnine-tenths engine speed for the nine-cylinder engines. Each of thesecams has four or five points respectively, to suit the number ofcylinders. The steel cylinders are machined from solid forgings and provided withwebs for air-cooling as shown. Cast-iron pistons are used, and areconnected to the crankshaft in the same manner as with the Gnome and LeRhone engines. Petrol is sprayed into the crank case by a small gearedpump and the mixture is taken from there to the piston valves by radialpipes. Two separate pumps are used for lubrication, one forcing oil tothe crank-pin bearing and the other spraying the cylinders. Among other designs of rotary aero engines the E. J. C. Is noteworthy, in that the cylinders and crank case of this engine rotate in oppositedirections, and two air-screws are used, one being attached to the endof the crankshaft, and the other to the crank case. Another interestingtype is the Burlat rotary, in which both the cylinders and crankshaftrotate in the same direction, the rotation of the crankshaft being twicethat of the cylinders as regards speed. This engine is arranged towork on the four-stroke cycle with the crankshaft making four, and thecylinders two, revolutions per cycle. It would appear that the rotary type of engine is capable of but littlemore improvement--save for such devices as these of the last two enginesmentioned, there is little that Laurent Seguin has not already done inthe Gnome type. The limitation of the rotary lies in its high fuel andlubricating oil consumption, which renders it unsuited for long-distanceaero work; it was, in the war period, an admirable engine for suchshort runs as might be involved in patrol work 'over the lines, ' andfor similar purposes, but the watercooled Vee or even vertical, withits much lower fuel consumption, was and is to be preferred for distancework. The rotary air-cooled type has its uses, and for them it willprobably remain among the range of current types for some time to come. Experience of matters aeronautical is sufficient to show, however, thatprophecy in any direction is most unsafe. V. THE HORIZONTALLY-OPPOSED ENGINE Among the first internal combustion engines to be taken into use withaircraft were those of the horizontally-opposed four-stroke cycle type, and, in every case in which these engines were used, their excellentbalance and extremely even torque rendered them ideal-until thetremendous increase in power requirements rendered the type too long andbulky for placing in the fuselage of an aeroplane. As power increased, there came a tendency toward placing cylinders radially round a centralcrankshaft, and, as in the case of the early Anzani, it may be said thatthe radial engine grew out of the horizontal opposed piston type. Therewere, in 1910--that is, in the early days of small power units, ten different sizes of the horizontally opposed engine listed formanufacture, but increase in power requirements practically ruled outthe type for air work. The Darracq firm were the leading makers of these engines in 1910; theirsmallest size was a 24 horsepower engine, with two cylinders each of 5. 1inches bore by 4. 7 inches stroke. This engine developed its rated powerat 1, 500 revolutions per minute, and worked out at a weight of 5 lbs. Per horse-power. With these engines the cranks are so placed that tworegular impulses are given to the crankshaft for each cycle of working, an arrangement which permits of very even balancing of the inertiaforces of the engine. The Darracq firm also made a four-cylinderedhorizontal opposed piston engine, in which two revolutions were given tothe crankshaft per revolution, at equal angular intervals. The Dutheil-Chambers was another engine of this type, and hadthe distinction of being the second largest constructed. At 1, 000revolutions per minute it developed 97 horse-power; its four cylinderswere each of 4. 93 inches bore by 11. 8 inches stroke--an abnormally longstroke in comparison with the bore. The weight--which owing to the buildof the engine and its length of stroke was bound to be rather high, actually amounted to 8. 2 lbs. Per horse-power. Water cooling wasadopted, and the engine was, like the Darracq four-cylinder type, so arranged as to give two impulses per revolution at equal angularintervals of crankshaft rotation. One of the first engines of this type to be constructed in England wasthe Alvaston, a water-cooled model which was made in 20, 30, and 50brake horse-power sizes, the largest being a four-cylinder engine. Allthree sizes were constructed to run at 1, 200 revolutions per minute. Inthis make the cylinders were secured to the crank case by means offour long tie bolts passing through bridge pieces arranged across thecylinder heads, thus relieving the cylinder walls of all longitudinalexplosion stresses. These bridge pieces were formed from chromevanadium steel and milled to an 'H' section, and the bearings for thevalve-tappet were forged solid with them. Special attention was givento the machining of the interiors of the cylinders and the combustionheads, with the result that the exceptionally high compression of 95lbs. Per square inch was obtained, giving a very flexible engine. Thecylinder heads were completely water-jacketed, and copper water-jacketswere also fitted round the cylinders. The mechanically operated valveswere actuated by specially shaped cams, and were so arranged that onlytwo cams were required for the set of eight valves. The inlet valves atboth ends of the engine were connected by a single feed-pipe to whichthe carburettor was attached, the induction piping being arranged abovethe engine in an easily accessible position. Auxiliary air ports wereprovided in the cylinder walls so that the pistons overran them at theend of their stroke. A single vertical shaft running in ball-bearingsoperated the valves and water circulating pump, being driven by spiralgearing from the crankshaft at half speed. In addition to the excellentbalance obtained with this engine, the makers claimed with justice thatthe number of working parts was reduced to an absolute minimum. In the two-cylinder Darracq, the steel cylinders were machined fromsolid, and auxiliary exhaust ports, overrun by the piston at the innerend of its stroke, were provided in the cylinder walls, consisting of acircular row of drilled holes--this arrangement was subsequently adoptedon some of the Darracq racing car engines. The water jackets were ofcopper, soldered to the cylinder walls; both the inlet and exhaustvalves were located in the cylinder heads, being operated by rockers andpush-rods actuated by cams on the halftime shaft driven from one endof the crankshaft. Ignition was by means of a high-tension magneto, and long induction pipes connected the-ends of the cylinders to thecarburettor, the latter being placed underneath the engine. Lubricationwas effected by spraying oil into the crank case by means of a pump, anda second pump circulated the cooling water. Another good example of this type of engine was the Eole, which hadeight opposed pistons, each pair of which was actuated by a commoncombustion chamber at the centre of the engine, two crankshafts beingplaced at the outer ends of the engine. This reversal of the ordinaryarrangement had two advantages; it simplified induction, and furtherobviated the need for cylinder heads, since the explosion drove at twopiston heads instead of at one piston head and the top of the cylinder;against this, however, the engine had to be constructed strongly enoughto withstand the longitudinal stresses due to the explosions, as thecranks are placed on the outer ends and the cylinders and crank-casestake the full force of each explosion. Each crankshaft drove a separateair-screw. This pattern of engine was taken up by the Dutheil-Chambers firm inthe pioneer days of aircraft, when the firm in question produced sevendifferent sizes of horizontal engines. The Demoiselle monoplane usedby Santos-Dumont in 1909 was fitted with a two-cylinder, horizontally-opposed Dutheil-Chambers engine, which developed 25 brakehorse-power at a speed of 1, 100 revolutions per minute, the cylindersbeing of 5 inches bore by 5. 1 inches stroke, and the total weight of theengine being some 120 lbs. The crankshafts of these engines were usuallyfitted with steel flywheels in order to give a very even torque, the wheels being specially constructed with wire spokes. In all theDutheil-Chambers engines water cooling was adopted, and the cylinderswere attached to the crank cases by means of long bolts passing throughthe combustion heads. For their earliest machines, the Clement-Bayard firm constructedhorizontal engines of the opposed piston type. The best known of thesewas the 30 horse-power size, which had cylinders of 4. 7 inches diameterby 5. 1 inches stroke, and gave its rated power at 1, 200 revolutions perminute. In this engine the steel cylinders were secured to the crankcase by flanges, and radiating ribs were formed around the barrelto assist the air-cooling. Inlet and exhaust valves were actuated bypush-rods and rockers actuated from the second motion shaft mountedabove the crank case; this shaft also drove the high-tension magnetowith which the engine was fitted. A ring of holes drilled round eachcylinder constituted auxiliary ports which the piston uncovered at theinner end of its stroke, and these were of considerable assistance notonly in expelling exhaust gases, but also in moderating the temperatureof the cylinder and of the main exhaust valve fitted in the cylinderhead. A water-cooled Clement-Bayard horizontal engine was also made, andin this the auxiliary exhaust ports were not embodied; except in thisparticular, the engine was very similar to the water-cooled Darracq. The American Ashmusen horizontal engine, developing 100 horse-power, isprobably the largest example of this type constructed. It was made withsix cylinders arranged on each side of a common crank case, with longbolts passing through the cylinder heads to assist in holding them down. The induction piping and valve-operating gear were arranged below theengine, and the half-speed shaft carried the air-screw. Messrs Palons and Beuse, Germans, constructed a light-weight, air-cooled, horizontally-opposed engine, two-cylindered. In this thecast-iron cylinders were made very thin, and were secured to thecrank case by bolts passing through lugs cast on the outer ends ofthe cylinders; the crankshaft was made hollow, and holes were drilledthrough the webs of the connecting-rods in order to reduce the weight. The valves were fitted to the cylinder heads, the inlet valves being ofthe automatic type, while the exhaust valves were mechanically operatedfrom the cam-shaft by means of rockers and push-rods. Two carburettorswere fitted, to reduce the induction piping to a minimum; one wasattached to each combustion chamber, and ignition was by the normalhigh-tension magneto driven from the halftime shaft. There was also a Nieuport two-cylinder air-cooled horizontal engine, developing 35 horse-power when running at 1, 300 revolutions per minute, and being built at a weight of 5. 1 lbs. Per horse-power. The cylinderswere of 5. 3 inches diameter by 5. 9 inches stroke; the engine followedthe lines of the Darracq and Dutheil-Chambers pretty closely, and thuscalls for no special description. The French Kolb-Danvin engine of the horizontal type, first constructedin 1905, was probably the first two-stroke cycle engine designed tobe applied to the propulsion of aircraft; it never got beyond theexperimental stage, although its trials gave very good results. Steppedpistons were adopted, and the charging pump at one end was used toscavenge the power cylinder at the other ends of the engine, thetransfer ports being formed in the main casting. The openings of theseports were controlled at both ends by the pistons, and the location ofthe ports appears to have made it necessary to take the exhaust from thebottom of one cylinder and from the top of the other. The carburettedmixture was drawn into the scavenging cylinders, and the usualdeflectors were cast on the piston heads to assist in the scavenging andto prevent the fresh gas from passing out of the exhaust ports. VI. THE TWO-STROKE CYCLE ENGINE Although it has been little used for aircraft propulsion, thepossibilities of the two-stroke cycle engine render some study ofit desirable in this brief review of the various types of internalcombustion engine applicable both to aeroplanes and airships. Theoretically the two-stroke cycle engine--or as it is more commonlytermed, the 'two-stroke, ' is the ideal power producer; the doubling ofimpulses per revolution of the crankshaft should render it of very muchmore even torque than the four-stroke cycle types, while, theoretically, there should be a considerable saving of fuel, owing to the doubling ofthe number of power strokes per total of piston strokes. In practice, however, the inefficient scavenging of virtually every two-stroke cycleengine produced nullifies or more than nullifies its advantages over thefour-stroke cycle engine; in many types, too, there is a waste of fuelgases through the exhaust ports, and much has yet to be done in the wayof experiment and resulting design before the two-stroke cycle enginecan be regarded as equally reliable, economical, and powerful with itselder brother. The first commercially successful engine operating on the two-strokecycle was invented by Mr Dugald Clerk, who in 1881 proved the designfeasible. As is more or less generally understood, the exhaust gases ofthis engine are discharged from the cylinder during the time thatthe piston is passing the inner dead centre, and the compression, combustion, and expansion of the charge take place in similar mannerto that of the four-stroke cycle engine. The exhaust period is usuallycontrolled by the piston overrunning ports in the cylinder at the endof its working stroke, these ports communicating direct with the outerair--the complication of an exhaust valve is thus obviated; immediatelyafter the escape of the exhaust gases, charging of the cylinder occurs, and the fresh gas may be introduced either through a valve in thecylinder head or through ports situated diametrically opposite to theexhaust ports. The continuation of the outward stroke of the piston, after the exhaust ports have been closed, compresses the charge intothe combustion chamber of the cylinder, and the ignition of the mixtureproduces a recurrence of the working stroke. Thus, theoretically, is obtained the maximum of energy with the minimumof expenditure; in practice, however, the scavenging of the powercylinder, a matter of great importance in all internal combustionengines, is often imperfect, owing to the opening of the exhaust portsbeing of relatively short duration; clearing the exhaust gases out ofthe cylinder is not fully accomplished, and these gases mix with thefresh charge and detract from its efficiency. Similarly, owing to theshorter space of time allowed, the charging of the cylinder with thefresh mixture is not so efficient as in the four-stroke cycle type; thefresh charge is usually compressed slightly in a separate chamber--crankcase, independent cylinder, or charging pump, and is delivered tothe working cylinder during the beginning of the return stroke of thepiston, while in engines working on the four-stroke cycle principle acomplete stroke is devoted to the expulsion of the waste gases of theexhaust, and another full stroke to recharging the cylinder with freshexplosive mixture. Theoretically the two-stroke and the four-stroke cycle engines possessexactly the same thermal efficiency, but actually this is modified by aseries of practical conditions which to some extent tend to neutralisethe very strong case in favour of the two-stroke cycle engine. Thespecific capacity of the engine operating on the two-stroke principle istheoretically twice that of one operating on the four-stroke cycle, andconsequently, for equal power, the former should require only about halfthe cylinder volume of the latter; and, owing to the greater superficialarea of the smaller cylinder, relatively, the latter should be far moreeasily cooled than the larger four-stroke cycle cylinder; thus it shouldbe possible to get higher compression pressures, which in turn shouldresult in great economy of working. Also the obtaining of a workingimpulse in the cylinder for each revolution of the crankshaft shouldgive a great advantage in regularity of rotation--which it undoubtedlydoes--and the elimination of the operating gear for the valves, inletand exhaust, should give greater simplicity of design. In spite of all these theoretical--and some practical--advantages thefour-stroke cycle engine was universally adopted for aircraft work;owing to the practical equality of the two principles of operation, sofar as thermal efficiency and friction losses are concerned, there is nodoubt that the simplicity of design (in theory) and high power outputto weight ratio (also in theory) ought to have given the 'two-stroke'a place on the aeroplane. But this engine has to be developed so as toovercome its inherent drawbacks; better scavenging methods have yet tobe devised--for this is the principal drawback--before the two-strokecan come to its own as a prime mover for aircraft. Mr Dugald Clerk's original two-stroke cycle engine is indicated roughly, as regards principle, by the accompanying diagram, from which it willbe seen that the elimination of the ordinary inlet and exhaust valvesof the four-stroke type is more than compensated by a separate cylinderwhich, having a piston worked from the connecting-rod of the powercylinder, was used to charging, drawing the mixture from the carburettorpast the valve in the top of the charging cylinder, and then forcing itthrough the connecting pipe into the power cylinder. The inlet valvesboth on the charging and the power cylinders are automatic; when thepower piston is near the bottom of its stroke the piston in the chargingcylinder is compressing the carburetted air, so that as soon as thepressure within the power cylinder is relieved by the exit of the burntgases through the exhaust ports the pressure in the charging cylindercauses the valve in the head of the power cylinder to open, and freshmixture flows into the cylinder, replacing the exhaust gases. Afterthe piston has again covered the exhaust ports the mixture begins to becompressed, thus automatically closing the inlet valve. Ignitionoccurs near the end of the compression stroke, and the working strokeimmediately follows, thus giving an impulse to the crankshaft on everydown stroke of the piston. If the scavenging of the cylinder werecomplete, and the cylinder were to receive a full charge of freshmixture for every stroke, the same mean effective pressure as isobtained with four-stroke cycle engines ought to be realised, and atan equal speed of rotation this engine should give twice the powerobtainable from a four-stroke cycle engine of equal dimensions. Thisresult was not achieved, and, with the improvements in constructionbrought about by experiment up to 1912, the output was found to be onlyabout fifty per cent more than that of a four-stroke cycle engine of thesame size, so that, when the charging cylinder is included, this enginehas a greater weight per horse-power, while the lowest rate of fuelconsumption recorded was 0. 68 lb. Per horse-power per hour. In 1891 Mr Day invented a two-stroke cycle engine which used the crankcase as a scavenging chamber, and a very large number of these engineshave been built for industrial purposes. The charge of carburetted airis drawn through a non-return valve into the crank chamber during theupstroke of the piston, and compressed to about 4 lbs. Pressure persquare inch on the down stroke. When the piston approaches the bottomend of its stroke the upper edge first overruns an exhaust port, andalmost immediately after uncovers an inlet port on the opposite side ofthe cylinder and in communication with the crank chamber; the enteringcharge, being under pressure, assists in expelling the exhaust gasesfrom the cylinder. On the next upstroke the charge is compressed intothe combustion space of the cylinder, a further charge simultaneouslyentering the crank case to be compressed after the ignition for theworking stroke. To prevent the incoming charge escaping through theexhaust ports of the cylinder a deflector is formed on the top of thepiston, causing the fresh gas to travel in an upward direction, thusavoiding as far as possible escape of the mixture to the atmosphere. From experiments conducted in 1910 by Professor Watson and Mr Flemingit was found that the proportion of fresh gases which escaped unburntthrough the exhaust ports diminished with increase of speed; at 600revolutions per minute about 36 per cent of the fresh charge was lost;at 1, 200 revolutions per minute this was reduced to 20 per cent, and at1, 500 revolutions it was still farther reduced to 6 per cent. So much for the early designs. With regard to engines of this typespecially constructed for use with aircraft, three designs call forspecial mention. Messrs A. Gobe and H. Diard, Parisian engineers, produced an eight-cylindered two-stroke cycle engine of rotary design, the cylinders being co-axial. Each pair of opposite pistons was securedtogether by a rigid connecting rod, connected to a pin on a rotatingcrankshaft which was mounted eccentrically to the axis of rotationof the cylinders. The crankshaft carried a pinion gearing with aninternally toothed wheel on the transmission shaft which carried theair-screw. The combustible mixture, emanating from a common supply pipe, was led through conduits to the front ends of the cylinders, in whichthe charges were compressed before being transferred to the workingspaces through ports in tubular extensions carried by the pistons. These extensions had also exhaust ports, registering with ports in thecylinder which communicated with the outer air, and the extensions slidover depending cylinder heads attached to the crank case by long studs. The pump charge was compressed in one end of each cylinder, and thepump spaces each delivered into their corresponding adjacent combustionspaces. The charges entered the pump spaces during the suction periodthrough passages which communicated with a central stationary supplypassage at one end of the crank case, communication being cut off whenthe inlet orifice to the passage passed out of register with the portin the stationary member. The exhaust ports at the outer end of thecombustion space opened just before and closed a little later than theair ports, and the incoming charge assisted in expelling the exhaustgases in a manner similar to that of the earlier types of two-strokecycle engine; The accompanying rough diagram assists in showing theworking of this engine. Exhibited in the Paris Aero Exhibition of 1912, the Laviator two-strokecycle engine, six-cylindered, could be operated either as a radial oras a rotary engine, all its pistons acting on a single crank. Cylinderdimensions of this engine were 3. 94 inches bore by 5. 12 inches stroke, and a power output of 50 horse-power was obtained when working at a rateof 1, 200 revolutions per minute. Used as a radial engine, it developed65 horse-power at the same rate of revolution, and, as the total weightwas about 198 lbs. , the weight of about 3 lbs. Per horse-power wasattained in radial use. Stepped pistons were employed, the annular spacebetween the smaller or power piston and the walls of the larger cylinderbeing used as a charging pump for the power cylinder situated 120degrees in rear of it. The charging cylinders were connected by shortpipes to ports in the crank case which communicated with the hollowcrankshaft through which the fresh gas was supplied, and once in eachrevolution each port in the case registered with the port in thehollow shaft. The mixture which then entered the charging cylinder wastransferred to the corresponding working cylinder when the piston ofthat cylinder had reached the end of its power stroke, and immediatelybefore this the exhaust ports diametrically opposite the inlet portswere uncovered; scavenging was thus assisted in the usual way. The verydesirable feature of being entirely valveless was accomplished with thisengine, which is also noteworthy for exceedingly compact design. The Lamplough six-cylinder two-stroke cycle rotary, shown at the AeroExhibition at Olympia in 1911, had several innovations, including acharging pump of rotary blower type. With the six cylinders, six powerimpulses at regular intervals were given on each rotation; otherwise, the cycle of operations was carried out much as in other two-strokecycle engines. The pump supplied the mixture under slight pressure toan inlet port in each cylinder, which was opened at the same time as theexhaust port, the period of opening being controlled by the piston. Therotary blower sucked the mixture from the carburettor and delivered itto a passage communicating with the inlet ports in the cylinder walls. A mechanically-operated exhaust valve was placed in the centre of eachcylinder head, and towards the end of the working stroke this valveopened, allowing part of the burnt gases to escape to the atmosphere;the remainder was pushed out by the fresh mixture going in through theports at the bottom end of the cylinder. In practice, one or other ofthe cylinders was always taking fresh mixture while working, thereforethe delivery from the pump was continuous and the mixture had not to bestored under pressure. The piston of this engine was long enough to keep the ports coveredwhen it was at the top of the stroke, and a bottom ring was providedto prevent the mixture from entering the crank case. In addition topreventing leakage, this ring no doubt prevented an excess of oilworking up the piston into the cylinder. As the cylinder fired withevery revolution, the valve gear was of the simplest construction, afixed cam lifting each valve as the cylinder came into position. Thespring of the exhaust valve was not placed round the stem in the usualway, but at the end of a short lever, away from the heat of the exhaustgases. The cylinders were of cast steel, the crank case of aluminium, and ball-bearings were fitted to the crankshaft, crank pins, and therotary blower pump. Ignition was by means of a high-tension magneto ofthe two-spark pattern, and with a total weight of 300 lbs. The maximumoutput was 102 brake horse-power, giving a weight of just under 3 lbs. Per horse-power. One of the most successful of the two-stroke cycle engines was thatdesigned by Mr G. F. Mort and constructed by the New Engine Company. With four cylinders of 3. 69 inches bore by 4. 5 inches stroke, andrunning at 1, 250 revolutions per minute, this engine developed 50 brakehorse-power; the total weight of the engine was 155 lbs. , thus giving aweight of 3. 1 lbs. Per horse-power. A scavenging pump of the rotary typewas employed, driven by means of gearing from the engine crankshaft, andin order to reduce weight to a minimum the vanes were of aluminium. Thisengine was tried on a biplane, and gave very satisfactory results. American design yields two apparently successful two-stroke cycle aeroengines. A rotary called the Fredericson engine was said to give anoutput of 70 brake horse-power with five cylinders 4. 5 inches diameterby 4. 75 inches stroke, running at 1, 000 revolutions per minute. Another, the Roberts two-stroke cycle engine, yielded 100 brake horse-powerfrom six cylinders of the stepped piston design; two carburettors, eachsupplying three cylinders, were fitted to this engine. Ignition wasby means of the usual high-tension magneto, gear-driven from thecrankshaft, and the engine, which was water-cooled, was of compactdesign. It may thus be seen that the two-stroke cycle type got as far as actualexperiment in air work, and that with considerable success. So far, however, the greater reliability of the four-stroke cycle has renderedit practically the only aircraft engine, and the two-stroke has yet someway to travel before it becomes a formidable competitor, in spite of itsadmitted theoretical and questioned practical advantages. VII. ENGINES OF THE WAR PERIOD The principal engines of British, French, and American design used inthe war period and since are briefly described under the four distincttypes of aero engine; such notable examples as the Rolls-Royce, Sunbeam, and Napier engines have been given special mention, as theyembodied--and still embody--all that is best in aero engine practice. Sofar, however, little has been said about the development of German aeroengine design, apart from the early Daimler and other pioneer makes. At the outbreak of hostilities in 1914, thanks to subsidies tocontractors and prizes to aircraft pilots, the German aeroplaneindustry was in a comparatively flourishing condition. There were abouttwenty-two establishments making different types of heavier-than-airmachines, monoplane and biplane, engined for the most part with thefour-cylinder Argus or the six-cylinder Mercedes vertical type engines, each of these being of 100 horse-power--it was not till war broughtincreasing demands on aircraft that the limit of power began to rise. Contemporary with the Argus and Mercedes were the Austro-Daimler, Benz, and N. A. G. , in vertical design, while as far as rotary types wereconcerned there were two, the Oberursel and the Stahlhertz; of these theformer was by far the most promising, and it came to virtual monopolyof the rotary-engined plane as soon as the war demand began. It waspractically a copy of the famous Gnome rotary, and thus deserves littledescription. Germany, from the outbreak of war, practically, concentrated on thedevelopment of the Mercedes engine; and it is noteworthy that, with oneexception, increase of power corresponding with the increased demandfor power was attained without increasing the number of cylinders. Thevarious models ranged between 75 and 260 horse-power, the latter beingthe most recent production of this type. The exception to the rulewas the eight-cylinder 240 horse-power, which was replaced by the 260horse-power six-cylinder model, the latter being more reliable and butvery slightly heavier. Of the other engines, the 120 horsepower Argusand the 160 and 225 horse-power Benz were the most used, the Oberurselbeing very largely discarded after the Fokker monoplane had had its day, and the N. A. G. And Austro-Daimler Daimler also falling to comparativedisuse. It may be said that the development of the Mercedes enginecontributed very largely to such success as was achieved in the warperiod by German aircraft, and, in developing the engine, the builderswere careful to make alterations in such a way as to effect the leastpossible change in the design of aeroplane to which they were to befitted. Thus the engine base of the 175 horse-power model coincidedprecisely with that of the 150 horse-power model, and the 200 and 240horse-power models retained the same base dimensions. It was estimated, in 1918, that well over eighty per cent of German aircraft was enginedwith the Mercedes type. In design and construction, there was nothing abnormal about theMercedes engine, the keynote throughout being extreme reliability andsuch simplification of design as would permit of mass production indifferent factories. Even before the war, the long list of records setup by this engine formed practical application of the wisdom of thispolicy; Bohn's flight of 24 hours 10 minutes, accomplished on July 10thand 11th, 1914, 9is an instance of this--the flight was accomplished onan Albatross biplane with a 75 horsepower Mercedes engine. The radialtype, instanced in other countries by the Salmson and Anzani makes, wasnot developed in Germany; two radial engines were made in that countrybefore the war, but the Germans seemed to lose faith in the type underwar conditions, or it may have been that insistence on standardisationruled out all but the proved examples of engine. Details of one of the middle sizes of Mercedes motor, the 176horse-power type, apply very generally to the whole range; this size wasin use up to and beyond the conclusion of hostilities, and it may stillbe regarded as characteristic of modern (1920) German practice. Theengine is of the fixed vertical type, has six cylinders in line, notoff-set, and is water-cooled. The cam shaft is carried in a specialbronze casing, seated on the immediate top of the cylinders, and avertical shaft is interposed between crankshaft and camshaft, the latterbeing driven by bevel gearing. On this vertical connecting-shaft the water pump is located, serving tosteady the motion of the shaft. Extending immediately below the camshaftis another vertical shaft, driven by bevel gears from the crank-shaft, and terminating in a worm which drives the multiple piston oil pumps. The cylinders are made from steel forgings, as are the valve chamberelbows, which are machined all over and welded together. A jacket oflight steel is welded over the valve elbows and attached to a flangeon the cylinders, forming a water-cooling space with a section of about7/16 of an inch. The cylinder bore is 5. 5 inches, and the stroke 6. 29inches. The cylinders are attached to the crank case by means of dogsand long through bolts, which have shoulders near their lower ends andare bolted to the lower half of the crank chamber. A very light andrigid structure is thus obtained, and the method of construction won theflattery of imitation by makers of other nationality. The cooling system for the cylinders is extremely efficient. Afterleaving the water pump, the water enters the top of the front cylindersand passes successively through each of the six cylinders of the row;short tubes, welded to the tops of the cylinders, serve as connectinglinks in the system. The Panhard car engines for years were fitted witha similar cooling system, and the White and Poppe lorry engines werealso similarly fitted; the system gives excellent cooling effect whereit is most needed, round the valve chambers and the cylinder heads. The pistons are built up from two pieces; a dropped forged steel pistonhead, from which depend the piston pin bosses, is combined with acast-iron skirt, into which the steel head is screwed. Four rings arefitted, three at the upper and one at the lower end of the piston skirt, and two lubricating oil grooves are cut in the skirt, in addition to thering grooves. Two small rivets retain the steel head on the piston skirtafter it has been screwed into position, and it is also welded at twopoints. The coefficient of friction between the cast-iron and steel isconsiderably less than that which would exist between two steel parts, and there is less tendency for the skirt to score the cylinder wallsthan would be the case if all steel were used--so noticeable is thisthat many makers, after giving steel pistons a trial, discarded them infavour of cast-iron; the Gnome is an example of this, being originallyfitted with a steel piston carrying a brass ring, discarded in favour ofa cast-iron piston with a percentage of steel in the metal mixture. Inthe Le Rhone engine the difficulty is overcome by a cast-iron liner tothe cylinders. The piston pin of the Mercedes is of chrome nickel steel, and isretained in the piston by means of a set screw and cotter pin. Theconnecting rods, of I section, are very short and rigid, carryingfloating bronze bushes which fit the piston pins at the small end, andcarrying an oil tube on each for conveying oil from the crank pin to thepiston pin. The crankshaft is of chrome nickel steel, carried on seven bearings. Holes are drilled through each of the crank pins and main bearings, forhalf the diameter of the shaft, and these are plugged with pressed brassstuds. Small holes, drilled through the crank cheeks, serve to conveylubricant from the main bearings to the crank pins. The propeller thrustis taken by a simple ball thrust bearing at the propeller end of thecrankshaft, this thrust bearing being seated in a steel retainer whichis clamped between the two halves of the crank case. At the forward endof the crankshaft there is mounted a master bevel gear on six splines;this bevel floats on the splines against a ball thrust bearing, and, in turn, the thrust is taken by the crank case cover. A stuffingbox prevents the loss of lubricant out of the front end of the crankchamber, and an oil thrower ring serves a similar purpose at thepropeller end of the crank chamber. With a motor speed of 1, 450 r. P. M. , the vertical shaft at the forwardend of the motor turns at 2, 175 r. P. M. , this being the speed of the twomagnetos and the water pump. The lower vertical shaft bevel gear and themagneto driving gear are made integral with the vertical driving shaft, which is carried in plain bearings in an aluminium housing. This housingis clamped to the upper half of the crank case by means of three studs. The cam-shaft carries eighteen cams, these being the inlet and exhaustcams, and a set of half compression cams which are formed with theexhaust cams and are put into action when required by means of a leverat the forward end of the cam-shaft. The cam-shaft is hollow, andserves as a channel for the conveyance of lubricating oil to each ofthe camshaft bearings. At the forward end of this shaft there is alsomounted an air pump for maintaining pressure on the fuel supply tank, and a bevel gear tachometer drive. Lubrication of the engine is carried out by a full pressure system. The oil is pumped through a single manifold, with seven branches to thecrankshaft main bearings, and then in turn through the hollow crankshaftto the connecting-rod big ends and thence through small tubes, alreadynoted, to the small end bearings. The oil pump has four pistons and twodouble valves driven from a single eccentric shaft on which are mountedfour eccentrics. The pump is continuously submerged in oil; in order toavoid great variations in pressure in the oil lines there is a pistonoperated pressure regulator, cut in between the pump and the oil lines. The two small pistons of the pump take fresh oil from a tank located inthe fuselage of the machine; one of these delivers oil to the cam shaft, and one delivers to the crankshaft; this fresh oil mixes with the usedoil, returns to the base, and back to the main large oil pump cylinders. By means of these small pump pistons a constant quantity of oil is keptin the motor, and the oil is continually being freshened by means of thenew oil coming in. All the oil pipes are very securely fastened to thelower half of the crank case, and some cooling of the oil is effectedby air passing through channels cast in the crank case on its way to thecarburettor. A light steel manifold serves to connect the exhaust ports of thecylinders to the main exhaust pipe, which is inclined about 25 degreesfrom vertical and is arranged to give on to the atmosphere just over thetop of the upper wing of the aeroplane. As regards carburation, an automatic air valve surrounds the throat ofthe carburettor, maintaining normal composition of mixture. A small jetis fitted for starting and running without load. The channels cast inthe crank chamber, already alluded to in connection with oil-cooling, serve to warm the air before it reaches the carburettor, of which thebody is water-jacketed. Ignition of the engine is by means of two Bosch ZH6 magnetos, driven ata speed of 2, 175 revolutions per minute when the engine is running atits normal speed of 1, 450 revolutions. The maximum advance of spark is12 mm. , or 32 degrees before the top dead centre, and the firing orderof the cylinders is 1, 5, 3, 6, 2, 4. The radiator fitted to this engine, together with the water-jackets, has a capacity of 25 litres of water, it is rectangular in shape, and isnormally tilted at an angle of 30 degrees from vertical. Its weight is26 kg. , and it offers but slight head resistance in flight. The radial type of engine, neglected altogether in Germany, was broughtto a very high state of perfection at the end of the War period byBritish makers. Two makes, the Cosmos Engineering Company's 'Jupiter'and 'Lucifer, ' and the A. B. C. 'Wasp II' and 'Dragon Fly 1A' requirespecial mention for their light weight and reliability on trials. The Cosmos 'Jupiter' was--for it is no longer being made--a 450horse-power nine-cylinder radial engine, air-cooled, with the cylindersset in one single row; it was made both geared to reduce the propellerrevolutions relatively to the crankshaft revolutions, and ungeared;the normal power of the geared type was 450 horse-power, and the totalweight of the engine, including carburettors, magnetos, etc. , was only757 lbs. ; the engine speed was 1, 850 revolutions per minute, and thepropeller revolutions were reduced by the gearing to 1, 200. Fitted to a'Bristol Badger' aeroplane, the total weight was 2, 800 lbs. , includingpilot, passenger, two machine-guns, and full military load; at 7, 000feet the registered speed, with corrections for density, was 137 milesper hour; in climbing, the first 2, 000 feet was accomplished in 1 minute4 seconds; 4, 000 feet was reached in 2 minutes 10 seconds; 6, 000 feetwas reached in 3 minutes 33 seconds, and 7, 000 feet in 4 minutes 15seconds. It was intended to modify the plane design and fit a newpropeller, in order to attain even better results, but, if trials weremade with these modifications, the results are not obtainable. The Cosmos 'Lucifer' was a three-cylinder radial type engine of 100horse-power, inverted Y design, made on the simplest possible principleswith a view to quantity production and extreme reliability. The rated100 horse-power was attained at 1, 600 revolutions per minute, and thecylinder dimensions were 5. 75 bore by 6. 25 inches stroke. The cylinderswere of aluminium and steel mixture, with aluminium heads; overheadvalves, operated by push rods on the front side of the cylinders, werefitted, and a simple reducing gear ran them at half engine speed. Thecrank case was a circular aluminium casting, the engine being attachedto the fuselage of the aeroplane by a circular flange situated at theback of the case; propeller shaft and crankshaft were integral. Dualignition was provided, the generator and distributors being driven offthe back end of the engine and the distributors being easily accessible. Lubrication was by means of two pumps, one scavenging and one suction, oil being fed under pressure from the crankshaft. A single carburettorfed all three cylinders, the branch pipe from the carburettor to thecircular ring being provided with an exhaust heater. The total weight ofthe engine, 'all on, ' was 280 lbs. The A. B. C. 'Wasp II, ' made by Walton Motors, Limited, is aseven-cylinder radial, air-cooled engine, the cylinders having a boreof 4. 75 inches and stroke 6. 25 inches. The normal brake horse-powerat 1, 650 revolutions is 160, and the maximum 200 at a speed of 1, 850revolutions per minute. Lubrication is by means of two rotary pumps, one feeding through the hollow crankshaft to the crank pin, givingcentrifugal feed to big end and thence splash oiling, and one feeding tothe nose of the engine, dropping on to the cams and forming a permanentsump for the gears on the bottom of the engine nose. Two carburettorsare fitted, and two two-spark magnetos, running at one andthree-quarters engine speed. The total weight of this engine is 350lbs. , or 1. 75 lbs. Per horse-power. Oil consumption at 1, 850 revolutionsis. 03 pints per horse-power per hour, and petrol consumption is. 56 pintsper horsepower per hour. The engine thus shows as very economical inconsumption, as well as very light in weight. The A. B. C. 'Dragon Fly 1A 'is a nine-cylinder radial engine havingone overhead inlet and two overhead exhaust valves per cylinder. Thecylinder dimensions are 5. 5 inches bore by 6. 5 inches stroke, andthe normal rate of speed, 1, 650 revolutions per minute, gives 340horse-power. The oiling is by means of two pumps, the system beingpractically identical with that of the 'Wasp II. ' Oil consumptionis. 021 pints per brake horse-power per hour, and petrol consumption. 56pints--the same as that of the 'Wasp II. ' The weight of the completeengine, including propeller boss, is 600 lbs. , or 1, 765 lbs. Perhorse-power. These A. B. C. Radials have proved highly satisfactory on tests, and theirextreme simplicity of design and reliability commend them as engineeringproducts and at the same time demonstrate the value, for aero work, ofthe air-cooled radial design--when this latter is accompanied by soundworkmanship. These and the Cosmos engines represent the minimum ofweight per horse-power yet attained, together with a practicable degreeof reliability, in radial and probably any aero engine design. APPENDIX A GENERAL MENSIER'S REPORT ON THE TRIALS OF CLEMENT ADER'S AVION. Paris, October 21, 1897. Report on the trials of M. Clement Ader's aviation apparatus. M. Ader having notified the Minister of War by letter, July 21, 1897, that the Apparatus of Aviation which he had agreed to build under theconditions set forth in the convention of July 24th, 1894, was ready, and therefore requesting that trials be undertaken before a Committeeappointed for this purpose as per the decision of August 4th, theCommittee was appointed as follows:-- Division General Mensier, Chairman; Division General Delambre, InspectorGeneral of the Permanent Works of Coast Defence, Member of the TechnicalCommittee of the Engineering Corps; Colonel Laussedat, Director of theConservatoire des Arts et Metiers; Sarrau, Member of the Institute, Professor of Mechanical Engineering at the Polytechnic School; Leaute, Member of the Institute, Professor of Mechanical Engineering at thePolytechnique School. Colonel Laussedat gave notice at once that his health and work asDirector of the Conservatoire des Arts et Metiers did not permit himto be a member of the Committee; the Minister therefore accepted hisresignation on September 24th, and decided not to replace him. Later on, however, on the request of the Chairman of the Committee, theMinister appointed a new member General Grillon, commanding the EngineerCorps of the Military Government of Paris. To carry on the trials which were to take place at the camp of Satory, the Minister ordered the Governor of the Military Forces of Paris torequisition from the Engineer Corps, on the request of the Chairman ofthe Committee, the men necessary to prepare the grounds at Satory. After an inspection made on the 16th an aerodrome was chosen. M. Ader'sidea was to have it of circular shape with a width of 40 metres and anaverage diameter of 450 metres. The preliminary work, laying out thegrounds, interior and exterior circumference, etc. , was finished at theend of August; the work of smoothing off the grounds began September 1stwith forty-five men and two rollers, and was finished on the day of thefirst tests, October 12th. The first meeting of the Committee was held August 18th in M. Ader'sworkshop; the object being to demonstrate the machine to the Committeeand give all the information possible on the tests that were to be held. After a careful examination and after having heard all the explanationsby the inventor which were deemed useful and necessary, the Committeedecided that the apparatus seemed to be built with a perfectunderstanding of the purpose to be fulfilled as far as one could judgefrom a study of the apparatus at rest; they therefore authorised M. Aderto take the machine apart and carry it to the camp at Satory so as toproceed with the trials. By letter of August 19th the Chairman made report to the Minister of thefindings of the Committee. The work on the grounds having taken longer than was anticipated, theChairman took advantage of this delay to call the Committee togetherfor a second meeting, during which M. Ader was to run the two propulsivescrews situated at the forward end of the apparatus. The meeting was held October 2nd. It gave the Committee an opportunityto appreciate the motive power in all its details; firebox, boiler, engine, under perfect control, absolute condensation, automatic fueland feed of the liquid to be vaporised, automatic lubrication andscavenging; everything, in a word, seemed well designed and executed. The weights in comparison with the power of the engine realised aconsiderable advance over anything made to date, since the two enginesweighed together realised 42 kg. , the firebox and boiler 60 kg. , thecondenser 15 kg. , or a total of 117 kg. For approximately 40 horse-poweror a little less than 3 kg. Per horse-power. One of the members summed up the general opinion by saying: 'Whatevermay be the result from an aviation point of view, a result which couldnot be foreseen for the moment, it was nevertheless proven that froma mechanical point of view M. Ader's apparatus was of the greatestinterest and real ingeniosity. He expressed a hope that in any case themachine would not be lost to science. ' The second experiment in the workshop was made in the presence of theChairman, the purpose being to demonstrate that the wings, having aspread of 17 metres, were sufficiently strong to support the weight ofthe apparatus. With this object in view, 14 sliding supports were placedunder each one of these, representing imperfectly the manner in whichthe wings would support the machine in the air; by gradually raising thesupports with the slides, the wheels on which the machine rested werelifted from the ground. It was evident at that time that the memberscomposing the skeleton of the wings supported the apparatus, and it wasquite evident that when the wings were supported by the air on everypoint of their surface, the stress would be better equalised than whenresting on a few supports, and therefore the resistance to breakagewould be considerably greater. After this last test, the work on the ground being practically finished, the machine was transported to Satory, assembled and again made readyfor trial. At first M. Ader was to manoeuvre the machine on the ground at amoderate speed, then increase this until it was possible to judgewhether there was a tendency for the machine to rise; and it was onlyafter M. Ader had acquired sufficient practice that a meeting of theCommittee was to be called to be present at the first part of thetrials; namely, volutions of the apparatus on the ground. The first test took place on Tuesday, October 12th, in the presenceof the Chairman of the Committee. It had rained a good deal during thenight and the clay track would have offered considerable resistance tothe rolling of the machine; furthermore, a moderate wind was blowingfrom the south-west, too strong during the early part of the afternoonto allow of any trials. Toward sunset, however, the wind having weakened, M. Ader decided tomake his first trial; the machine was taken out of its hangar, the wingswere mounted and steam raised. M. Ader in his seat had, on each side ofhim, one man to the right and one to the left, whose duty was to rectifythe direction of the apparatus in the event that the action of therear wheel as a rudder would not be sufficient to hold the machine in astraight course. At 5. 25 p. M. The machine was started, at first slowly and then at anincreased speed; after 250 or 300 metres, the two men who were beingdragged by the apparatus were exhausted and forced to fall flat onthe ground in order to allow the wings to pass over them, and thetrip around the track was completed, a total of 1, 400 metres, withoutincident, at a fair speed, which could be estimated to be from 300 to400 metres per minute. Notwithstanding M. Ader's inexperience, thisbeing the first time that he had run his apparatus, he followedapproximately the chalk line which marked the centre of the track and hestopped at the exact point from which he started. The marks of the wheels on the ground, which was rather soft, did notshow up very much, and it was clear that a part of the weight of theapparatus had been supported by the wings, though the speed was onlyabout one-third of what the machine could do had M. Ader used all itsmotive power; he was running at a pressure of from 3 to 4 atmospheres, when he could have used 10 to 12. This first trial, so fortunately accomplished, was of great importance;it was the first time that a comparatively heavy vehicle (nearly 400kg. , including the weight of the operator, fuel, and water) had been setin motion by a tractive apparatus, using the air solely as a propellingmedium. The favourable report turned in by the Committee after themeeting of October 2nd was found justified by the results demonstratedon the grounds, and the first problem of aviation, namely, the creationof efficient motive power, could be considered as solved, since thepropulsion of the apparatus in the air would be a great deal easierthan the traction on the ground, provided that the second part of theproblem, the sustaining of the machine in the air, would be realised. The next day, Wednesday the 13th, no further trials were made on accountof the rain and wind. On Thursday the 14th the Chairman requested that General Grillon, whohad just been appointed a member of the Committee, accompany him so asto have a second witness. The weather was fine, but a fairly strong, gusty wind was blowing fromthe south. M. Ader explained to the two members of the Committee thedanger of these gusts, since at two points of the circumference the windwould strike him sideways. The wind was blowing in the direction A B, the apparatus starting from C, and running in the direction shown by thearrow. The first dangerous spot would be at B. The apparatus had beenkept in readiness in the event of the wind dying down. Toward sunset thewind seemed to die down, as it had done on the evening of the 12th. M. Ader hesitated, which, unfortunately, further events only justified, butdecided to make a new trial. At the start, which took place at 5. 15 p. M. , the apparatus, havingthe wind in the rear, seemed to run at a fairly regular speed; it was, nevertheless, easy to note from the marks of the wheels on the groundthat the rear part of the apparatus had been lifted and that the rearwheel, being the rudder, had not been in constant contact with theground. When the machine came to the neighbourhood of B, the two membersof the Committee saw the machine swerve suddenly out of the track in asemicircle, lean over to the right and finally stop. They immediatelyproceeded to the point where the accident had taken place andendeavoured to find an explanation for the same. The Chairman finallydecided as follows: M. Ader was the victim of a gust of wind which he had feared as heexplained before starting out; feeling himself thrown out of his course, he tried to use the rudder energetically, but at that time the rearwheel was not in contact with the ground, and therefore did notperform its function; the canvas rudder, which had as its purpose themanoeuvring of the machine in the air, did not have sufficient actionon the ground. It would have been possible without any doubt to reactby using the propellers at unequal speed, but M. Ader, being stillinexperienced, had not thought of this. Furthermore, he was thrownout of his course so quickly that he decided, in order to avoid a moreserious accident, to stop both engines. This sudden stop produced thehalf-circle already described and the fall of the machine on its side. The damage to the machine was serious; consisting at first sight of therupture of both propellers, the rear left wheel and the bending of theleft wing tip. It will only be possible to determine after the machineis taken apart whether the engine, and more particularly the organs oftransmission, have been put out of line. Whatever the damage may be, though comparatively easy to repair, it willtake a certain amount of time, and taking into consideration the timeof year it is evident that the tests will have to be adjourned for thepresent. As has been said in the above report, the tests, though prematurelyinterrupted, have shown results of great importance, and though thefinal results are hard to foresee, it would seem advisable to continuethe trials. By waiting for the return of spring there will be plenty oftime to finish the tests and it will not be necessary to rush matters, which was a partial cause of the accident. The Chairman of the Committeepersonally has but one hope, and that is that a decision be reachedaccordingly. Division General, Chairman of the Committee, Mensier. Boulogne-sur-Seine, October 21st, 1897. Annex to the Report of October 21st. General Grillon, who was present at the trials of the 14th, and who sawthe report relative to what happened during that day, made the followingobservations in writing, which are reproduced herewith in quotationmarks. The Chairman of the Committee does not agree with General Grillonand he answers these observations paragraph by paragraph. 1. 'If the rear wheel (there is only one of these) left but intermittenttracks on the ground, does that prove that the machine has a tendency torise when running at a certain speed?' Answer. --This does not prove anything in any way, and I was very carefulnot to mention this in my report, this point being exactly what wasneeded and that was not demonstrated during the two tests made on thegrounds. 'Does not this unequal pressure of the two pair of wheels on the groundshow that the centre of gravity of the apparatus is placed too farforward and that under the impulse of the propellers the machine has atendency to tilt forward, due to the resistance of the air?' Answer. --The tendency of the apparatus to rise from the rear when it wasrunning with the wind seemed to be brought about by the effects of thewind on the huge wings, having a spread of 17 metres, and I believe thatwhen the machine would have faced the wind the front wheels would havebeen lifted. During the trials of October 12th, when a complete circuit of the trackwas accomplished without incidents, as I and Lieut. Binet witnessed, there was practically no wind. I was therefore unable to verify whetherduring this circuit the two front wheels or the rear wheel were inconstant contact with the ground, because when the trial was over it wasdark (it was 5. 30) and the next day it was impossible to see anythingbecause it had rained during the night and during Wednesday morning. Butwhat would prove that the rear wheel was in contact with the ground atall times is the fact that M. Ader, though inexperienced, did not swervefrom the circular track, which would prove that he steered pretty wellwith his rear wheel--this he could not have done if he had been in theair. In the tests of the 12th, the speed was at least as great as on the14th. 2. 'It would seem to me that if M. Ader thought that his rear wheelswere off the ground he should have used his canvas rudder in order toregain his proper course; this was the best way of causing the machineto rotate, since it would have given an angular motion to the frontaxle. ' Answer. --I state in my report that the canvas rudder whose object wasthe manoeuvre of the apparatus in the air could have no effect on theapparatus on the ground, and to convince oneself of this point it isonly necessary to consider the small surface of this canvas ruddercompared with the mass to be handled on the ground, a weight ofapproximately 400 kg. According to my idea, and as I have stated in myreport, M. Ader should have steered by increasing the speed on one ofhis propellers and slowing down the other. He admitted afterward thatthis remark was well founded, but that he did not have time to think ofit owing to the suddenness of the accident. 3. 'When the apparatus fell on its side it was under the sole influenceof the wind, since M. Ader had stopped the machine. Have we not a resulthere which will always be the same when the machine comes to the ground, since the engines will always have to be stopped or slowed down whencoming to the ground? Here seems to be a bad defect of the apparatusunder trial. ' Answer. --I believe that the apparatus fell on its side after coming toa stop, not on account of the wind, but because the semicircle describedwas on rough ground and one of the wheels had collapsed. Mensier. October 27th, 1897. APPENDIX B Specification and Claims of Wright Patent, No. 821393. Filed March 23rd, 1903. Issued May 22nd, 1906. Expires May 22nd, 1923. To all whom it may concern. Be it known that we, Orville Wright and Wilbur Wright, citizens of theUnited States, residing in the city of Dayton, county of Montgomery, and State of Ohio, have invented certain new and useful Improvements inFlying Machines, of which the following is a specification. Our invention relates to that class of flying-machines in whichthe weight is sustained by the reactions resulting when one or moreaeroplanes are moved through the air edgewise at a small angle ofincidence, either by the application of mechanical power or by theutilisation of the force of gravity. The objects of our invention are to provide means for maintainingor restoring the equilibrium or lateral balance of the apparatus, toprovide means for guiding the machine both vertically and horizontally, and to provide a structure combining lightness, strength, convenience ofconstruction and certain other advantages which will hereinafter appear. To these ends our invention consists in certain novel features, which wewill now proceed to describe and will then particularly point out in theclaims. In the accompanying drawings, Figure I 1 is a perspective viewof an apparatus embodying our invention in one form. Fig. 2 is a planview of the same, partly in horizontal section and partly broken away. Fig. 3 is a side elevation, and Figs. 4 and 5 are detail views, of oneform of flexible joint for connecting the upright standards with theaeroplanes. In flying machines of the character to which this invention relates theapparatus is supported in the air by reason of the contact between theair and the under surface of one or more aeroplanes, the contact surfacebeing presented at a small angle of incidence to the air. The relativemovements of the air and aeroplane may be derived from the motion ofthe air in the form of wind blowing in the direction opposite to that inwhich the apparatus is travelling or by a combined downward and forwardmovement of the machine, as in starting from an elevated position orby combination of these two things, and in either case the operation isthat of a soaring-machine, while power applied to the machine to propelit positively forward will cause the air to support the machine in asimilar manner. In either case owing to the varying conditions to bemet there are numerous disturbing forces which tend to shift the machinefrom the position which it should occupy to obtain the desired results. It is the chief object of our invention to provide means for remedyingthis difficulty, and we will now proceed to describe the construction bymeans of which these results are accomplished. In the accompanying drawing we have shown an apparatus embodying ourinvention in one form. In this illustrative embodiment the machine isshown as comprising two parallel superposed aeroplanes, 1 and 2, may beembodied in a structure having a single aeroplane. Each aeroplane is ofconsiderably greater width from side to side than from front to rear. The four corners of the upper aeroplane are indicated by the referenceletters a, b, c, and d, while the corresponding corners of the loweraeroplane 2 are indicated by the reference letters e, f, g, and h. Themarginal lines ab and ef indicate the front edges of the aeroplanes, thelateral margins of the upper aeroplane are indicated, respectively, by the lines ad and bc, the lateral margins of the lower aeroplane areindicated, respectively, by the lines eh and fg, while the rear marginsof the upper and lower aeroplanes are indicated, respectively, by thelines cd and gh. Before proceeding to a description of the fundamental theory ofoperation of the structure we will first describe the preferred mode ofconstructing the aeroplanes and those portions of the structure whichserve to connect the two aeroplanes. Each aeroplane is formed by stretching cloth or other suitable fabricover a frame composed of two parallel transverse spars 3, extendingfrom side to side of the machine, their ends being connected by bows 4extending from front to rear of the machine. The front and rear spars3 of each aeroplane are connected by a series of parallel ribs 5, whichpreferably extend somewhat beyond the rear spar, as shown. These spars, bows, and ribs are preferably constructed of wood having the necessarystrength, combined with lightness and flexibility. Upon this frameworkthe cloth which forms the supporting surface of the aeroplane issecured, the frame being enclosed in the cloth. The cloth for eachaeroplane previous to its attachment to its frame is cut on the biasand made up into a single piece approximately the size and shape of theaeroplane, having the threads of the fabric arranged diagonally to thetransverse spars and longitudinal ribs, as indicated at 6 in Fig. 2. Thus the diagonal threads of the cloth form truss systems with the sparsand ribs, the threads constituting the diagonal members. A hem is formedat the rear edge of the cloth to receive a wire 7, which is connected tothe ends of the rear spar and supported by the rearwardly-extending endsof the longitudinal ribs 5, thus forming a rearwardly-extending flapor portion of the aeroplane. This construction of the aeroplane givesa surface which has very great strength to withstand lateral andlongitudinal strains, at the same time being capable of being bent ortwisted in the manner hereinafter described. When two aeroplanes are employed, as in the construction illustrated, they are connected together by upright standards 8. These standards aresubstantially rigid, being preferably constructed of wood and of equallength, equally spaced along the front and rear edges of the aeroplane, to which they are connected at their top and bottom ends by hingedjoints or universal joints of any suitable description. We have shownone form of connection which may be used for this purpose in Figs. 4 and5 of the drawings. In this construction each end of the standard 8has secured to it an eye 9 which engages with a hook 10, secured to abracket plate 11, which latter plate is in turn fastened to the spar 3. Diagonal braces or stay-wires 12 extend from each end of each standardto the opposite ends of the adjacent standards, and as a convenient modeof attaching these parts I have shown a hook 13 made integral with thehook 10 to receive the end of one of the stay-wires, the other stay-wirebeing mounted on the hook 10. The hook 13 is shown as bent down toretain the stay-wire in connection to it, while the hook 10 is shownas provided with a pin 14 to hold the staywire 12 and eye 9 in positionthereon. It will be seen that this construction forms a truss systemwhich gives the whole machine great transverse rigidity and strength, while at the same time the jointed connections of the parts permit theaeroplanes to be bent or twisted in the manner which we will now proceedto describe. 15 indicates a rope or other flexible connection extending lengthwiseof the front of the machine above the lower aeroplane, passing underpulleys or other suitable guides 16 at the front corners e and f of thelower aeroplane, and extending thence upward and rearward to the upperrear corners c and d, of the upper aeroplane, where they are attached, as indicated at 17. To the central portion of the rope there isconnected a laterally-movable cradle 18, which forms a means for movingthe rope lengthwise in one direction or the other, the cradle beingmovable toward either side of the machine. We have devised this cradleas a convenient means for operating the rope 15, and the machine isintended to be generally used with the operator lying face downward onthe lower aeroplane, with his head to the front, so that the operator'sbody rests on the cradle, and the cradle can be moved laterally by themovements of the operator's body. It will be understood, however, thatthe rope 15 may be manipulated in any suitable manner. 19 indicates a second rope extending transversely of the machine alongthe rear edge of the body portion of the lower aeroplane, passing undersuitable pulleys or guides 20 at the rear corners g and h of the loweraeroplane and extending thence diagonally upward to the front corners aand b of the upper aeroplane, where its ends are secured in any suitablemanner, as indicated at 21. Considering the structure so far as we have now described it, andassuming that the cradle 18 be moved to the right in Figs. 1 and 2, as indicated by the arrows applied to the cradle in Fig. 1 and by thedotted lines in Fig. 2, it will be seen that that portion of the rope 15passing under the guide pulley at the corner e and secured to the cornerd will be under tension, while slack is paid out throughout the otherside or half of the rope 15. The part of the rope 15 under tensionexercises a downward pull upon the rear upper corner d of the structureand an upward pull upon the front lower corner e, as indicated by thearrows. This causes the corner d to move downward and the corner e tomove upward. As the corner e moves upward it carries the corner a upwardwith it, since the intermediate standard 8 is substantially rigid andmaintains an equal distance between the corners a and e at all times. Similarly, the standard 8, connecting the corners d and h, causes thecorner h to move downward in unison with the corner d. Since the cornera thus moves upward and the corner h moves downward, that portion ofthe rope 19 connected to the corner a will be pulled upward through thepulley 20 at the corner h, and the pull thus exerted on the rope 19 willpull the corner b on the other wise of the machine downward and at thesame time pull the corner g at said other side of the machine upward. This results in a downward movement of the corner b and an upwardmovement of the corner c. Thus it results from a lateral movement of thecradle 18 to the right in Fig. 1 that the lateral margins ad and eh atone side of the machine are moved from their normal positions in whichthey lie in the normal planes of their respective aeroplanes, intoangular relations with said normal planes, each lateral margin on thisside of the machine being raised above said normal plane at its forwardend and depressed below said normal plane at its rear end, said lateralmargins being thus inclined upward and forward. At the same time areverse inclination is imparted to the lateral margins bc end fg at theother side of the machine, their inclination being downward and forward. These positions are indicated in dotted lines in Fig. 1 of the drawings. A movement of the cradle 18 in the opposite direction from its normalposition will reverse the angular inclination of the lateral margins ofthe aeroplanes in an obvious manner. By reason of this construction itwill be seen that with the particular mode of construction now underconsideration it is possible to move the forward corner of the lateraledges of the aeroplane on one side of the machine either above or belowthe normal planes of the aeroplanes, a reverse movement of the forwardcorners of the lateral margins on the other side of the machineoccurring simultaneously. During this operation each aeroplane istwisted or distorted around a line extending centrally across the samefrom the middle of one lateral margin to the middle of the other lateralmargin, the twist due to the moving of the lateral margins to differentangles extending across each aeroplane from side to side, so that eachaeroplane surface is given a helicoidal warp or twist. We prefer thisconstruction and mode of operation for the reason that it gives agradually increasing angle to the body of each aeroplane from thecentre longitudinal line thereof outward to the margin, thus giving acontinuous surface on each side of the machine, which has a graduallyincreasing or decreasing angle of incidence from the centre of themachine to either side. We wish it to be understood, however, that ourinvention is not limited to this particular construction, since anyconstruction whereby the angular relations of the lateral margins ofthe aeroplanes may be varied in opposite directions with respect tothe normal planes of said aeroplanes comes within the scope of ourinvention. Furthermore, it should be understood that while the lateralmargins of the aeroplanes move to different angular positions withrespect to or above and below the normal planes of said aeroplanes, it does not necessarily follow that these movements bring the oppositelateral edges to different angles respectively above and below ahorizontal plane since the normal planes of the bodies of the aeroplanesare inclined to the horizontal when the machine is in flight, saidinclination being downward from front to rear, and while the forwardcorners on one side of the machine may be depressed below thenormal planes of the bodies of the aeroplanes said depression is notnecessarily sufficient to carry them below the horizontal planes passingthrough the rear corners on that side. Moreover, although we prefer toso construct the apparatus that the movements of the lateral marginson the opposite sides of the machine are equal in extent and opposite mdirection, yet our invention is not limited to a construction producingthis result, since it may be desirable under certain circumstancesto move the lateral margins on one side of the machine just describedwithout moving the lateral margins on the other side of the machine toan equal extent in the opposite direction. Turning now to the purpose ofthis provision for moving the lateral margins of the aeroplanes in themanner described, it should be premised that owing to various conditionsof wind pressure and other causes the body of the machine is apt tobecome unbalanced laterally, one side tending to sink and the other sidetending to rise, the machine turning around its central longitudinalaxis. The provision which we have just described enables the operatorto meet this difficulty and preserve the lateral balance of the machine. Assuming that for some cause that side of the machine which lies tothe left of the observer in Figs. 1 and 2 has shown a tendency to dropdownward, a movement of the cradle 18 to the right of said figures, asherein before assumed, will move the lateral margins of the aeroplanesin the manner already described, so that the margins ad and eh will beinclined downward and rearward, and the lateral margins bc and fg willbe inclined upward and rearward with respect to the normal planes of thebodies of the aeroplanes. With the parts of the machine in this positionit will be seen that the lateral margins ad and eh present a largerangle of incidence to the resisting air, while the lateral margins onthe other side of the machine present a smaller angle of incidence. Owing to this fact, the side of the machine presenting the larger angleof incidence will tend to lift or move upward, and this upward movementwill restore the lateral balance of the machine. When the other side ofthe machine tends to drop, a movement of the cradle 18 in the reversedirection will restore the machine to its normal lateral equilibrium. Ofcourse, the same effect will be produced in the same way in the case ofa machine employing only a single aeroplane. In connection with the body of the machine as thus operated we employa vertical rudder or tail 22, so supported as to turn around a verticalaxis. This rudder is supported at the rear ends on supports or arms 23, pivoted at their forward ends to the rear margins of the upper and loweraeroplanes, respectively. These supports are preferably V-shaped, asshown, so that their forward ends are comparatively widely separated, their pivots being indicated at 24. Said supports are free to swingupward at their free rear ends, as indicated in dotted lines in Fig. 3, their downward movement being limited in any suitable manner. Thevertical pivots of the rudder 22 are indicated at 25, and one of thesepivots has mounted thereon a sheave or pulley 26, around which passes atiller-rope 27, the ends of which are extended out laterally and securedto the rope 19 on opposite sides of the central point of said rope. Byreason of this construction the lateral shifting of the cradle 18 servesto turn the rudder to one side or the other of the line of flight. Itwill be observed in this connection that the construction is such thatthe rudder will always be so turned as to present its resistingsurface on that side of the machine on which the lateral margins of theaeroplanes present the least angle of resistance. The reason of thisconstruction is that when the lateral margins of the aeroplanes areso turned in the manner hereinbefore described as to present differentangles of incidence to the atmosphere, that side presenting the largestangle of incidence, although being lifted or moved upward in the manneralready described, at the same time meets with an increased resistanceto its forward motion, while at the same time the other side of themachine, presenting a smaller angle of incidence, meets with lessresistance to its forward motion and tends to move forward more rapidlythan the retarded side. This gives the machine a tendency to turn aroundits vertical axis, and this tendency if not properly met will not onlychange the direction of the front of the machine, but will ultimatelypermit one side thereof to drop into a position vertically below theother side with the aero planes in vertical position, thus causing themachine to fall. The movement of the rudder, hereinbefore described, prevents this action, since it exerts a retarding influence on that sideof the machine which tends to move forward too rapidly and keeps themachine with its front properly presented to the direction of flight andwith its body properly balanced around its central longitudinal axis. The pivoting of the supports 23 so as to permit them to swing upwardprevents injury to the rudder and its supports in case the machinealights at such an angle as to cause the rudder to strike the groundfirst, the parts yielding upward, as indicated in dotted lines in Fig. 3, and thus preventing injury or breakage. We wish it to be understood, however, that we do not limit ourselves to the particular description ofrudder set forth, the essential being that the rudder shall be verticaland shall be so moved as to present its resisting surface on that sideof the machine which offers the least resistance to the atmosphere, soas to counteract the tendency of the machine to turn around a verticalaxis when the two sides thereof offer different resistances to the air. From the central portion of the front of the machine struts 28 extendhorizontally forward from the lower aeroplane, and struts 29 extenddownward and forward from the central portion of the upper aeroplane, their front ends being united to the struts 28, the forward extremitiesof which are turned up, as indicated at 30. These struts 28 and 29 formtruss-skids projecting in front of the whole frame of the machineand serving to prevent the machine from rolling over forward when italights. The struts 29 serve to brace the upper portion of the mainframe and resist its tendency to move forward after the lower aeroplanehas been stopped by its contact with the earth, thereby relieving therope 19 from undue strain, for it will be understood that when themachine comes into contact with the earth, further forward movement ofthe lower portion thereof being suddenly arrested, the inertia of theupper portion would tend to cause it to continue to move forward ifnot prevented by the struts 29, and this forward movement of the upperportion would bring a very violent strain upon the rope 19, since itis fastened to the upper portion at both of its ends, while its lowerportion is connected by the guides 20 to the lower portion. The struts28 and 29 also serve to support the front or horizontal rudder, theconstruction of which we will now proceed to describe. The front rudder 31 is a horizontal rudder having a flexible body, thesame consisting of three stiff crosspieces or sticks 32, 33, and 34, andthe flexible ribs 35, connecting said cross-pieces and extending fromfront to rear. The frame thus provided is covered by a suitable fabricstretched over the same to form the body of the rudder. The rudder issupported from the struts 29 by means of the intermediate cross-piece32, which is located near the centre of pressure slightly in front ofa line equidistant between the front and rear edges of the rudder, the cross-piece 32 forming the pivotal axis of the rudder, so as toconstitute a balanced rudder. To the front edge of the rudder there areconnected springs 36 which springs are connected to the upturned ends 30of the struts 28, the construction being such that said springs tend toresist any movement either upward or downward of the front edge of thehorizontal rudder. The rear edge of the rudder lies immediately in frontof the operator and may be operated by him in any suitable manner. Wehave shown a mechanism for this purpose comprising a roller or shaft 37, which may be grasped by the operator so as to turn the same in eitherdirection. Bands 38 extend from the roller 37 forward to and around asimilar roller or shaft 39, both rollers or shafts being supported insuitable bearings on the struts 28. The forward roller or shaft hasrearwardly-extending arms 40, which are connected by links 41 with therear edge of the rudder 31. The normal position of the rudder 31 isneutral or substantially parallel with the aeroplanes 1 and 2; but itsrear edge may be moved upward or downward, so as to be above or belowthe normal plane of said rudder through the mechanism provided for thatpurpose. It will be seen that the springs 36 will resist any tendency ofthe forward edge of the rudder to move in either direction, so that whenforce is applied to the rear edge of said rudder the longitudinal ribs35 bend, and the rudder thus presents a concave surface to the action ofthe wind either above or below its normal plane, said surface presentinga small angle of incidence at its forward portion and said angle ofincidence rapidly increasing toward the rear. This greatly increases theefficiency of the rudder as compared with a plane surface of equal area. By regulating the pressure on the upper and lower sides of the rudderthrough changes of angle and curvature in the manner described aturning movement of the main structure around its transverse axis may beeffected, and the course of the machine may thus be directed upwardor downward at the will of the operator and the longitudinal balancethereof maintained. Contrary to the usual custom, we place the horizontal rudder in front ofthe aeroplanes at a negative angle and employ no horizontal tail at all. By this arrangement we obtain a forward surface which is almost entirelyfree from pressure under ordinary conditions of flight, but which evenif not moved at all from its original position becomes an efficientlifting-surface whenever the speed of the machine is accidentallyreduced very much below the normal, and thus largely counteracts thatbackward travel of the centre of pressure on the aeroplanes which hasfrequently been productive of serious injuries by causing the machineto turn downward and forward and strike the ground head-on. We are awarethat a forward horizontal rudder of different construction has been usedin combination with a supporting surface and a rear horizontal-rudder;but this combination was not intended to effect and does not effect theobject which we obtain by the arrangement hereinbefore described. We have used the term 'aeroplane' in this specification and the appendedclaims to indicate the supporting surface or supporting surfaces bymeans of which the machine is sustained in the air, and by this term wewish to be understood as including any suitable supporting surface whichnormally is substantially flat, although. Of course, when constructedof cloth or other flexible fabric, as we prefer to construct them, thesesurfaces may receive more or less curvature from the resistance of theair, as indicated in Fig. 3. We do not wish to be understood as limiting ourselves strictly to theprecise details of construction hereinbefore described and shown inthe accompanying drawings, as it is obvious that these details may bemodified without departing from the principles of our invention. Forinstance, while we prefer the construction illustrated in which eachaeroplane is given a twist along its entire length in order to set itsopposite lateral margins at different angles, we have already pointedout that our invention is not limited to this form of construction, since it is only necessary to move the lateral marginal portions, andwhere these portions alone are moved only those upright standards whichsupport the movable portion require flexible connections at their ends. Having thus fully described our invention, what we claim as new, anddesire to secure by Letters Patent, is:-- 1. In a flying machine, a normally flat aeroplane having lateralmarginal portions capable of movement to different positions above orbelow the normal plane of the body of the aeroplane, such movement beingabout an axis transverse to the line of flight, whereby said lateralmarginal portions may be moved to different angles relatively to thenormal plane of the body of the aeroplane, so as to present to theatmosphere different angles of incidence, and means for so moving saidlateral marginal portions, substantially as described. 2. In a flying machine, the combination, with two normally parallelaeroplanes, superposed the one above the other, of upright standardsconnecting said planes at their margins, the connections between thestandards and aeroplanes at the lateral portions of the aeroplanes beingby means of flexible joints, each of said aeroplanes having lateralmarginal portions capable of movement to different positions above orbelow the normal plane of the body of the aeroplane, such movement beingabout an axis transverse to the line of flight, whereby said lateralmarginal portions may be moved to different angles relatively to thenormal plane of the body of the aeroplane, so as to present to theatmosphere different angles of incidence, the standards maintaininga fixed distance between the portions of the aeroplanes which theyconnect, and means for imparting such movement to the lateral marginalportions of the aeroplanes, substantially as described. 3. In a flying machine, a normally flat aeroplane having lateralmarginal portions capable of movement to different positions above orbelow the normal plane of the body of the aeroplane, such movement beingabout an axis transverse to the line of flight, whereby said lateralmarginal portions may be moved to different angles relatively to thenormal plane of the body of the aeroplane, and also to different anglesrelatively to each other, so as to present to the atmosphere differentangles of incidence, and means for simultaneously imparting suchmovement to said lateral marginal portions, substantially as described. 4. In a flying machine, the combination, with parallel superposedaeroplanes, each having lateral marginal portions capable of movement todifferent positions above or below the normal plane of the body of theaeroplane, such movement being about an axis transverse to the line offlight, whereby said lateral marginal portions may be moved to differentangles relatively to the normal plane of the body of the aeroplane, andto different angles relatively to each other, so as to present to theatmosphere different angles of incidence, of uprights connecting saidaeroplanes at their edges, the uprights connecting the lateral portionsof the aeroplanes being connected with said aeroplanes by flexiblejoints, and means for simultaneously imparting such movement to saidlateral marginal portions, the standards maintaining a fixed distancebetween the parts which they connect, whereby the lateral portions onthe same side of the machine are moved to the same angle, substantiallyas described. 5. In a flying machine, an aeroplane having substantially the form of anormally flat rectangle elongated transversely to the line of flight, in combination which means for imparting to the lateral margins of saidaeroplane a movement about an axis lying in the body of the aeroplaneperpendicular to said lateral margins, and thereby moving said lateralmargins into different angular relations to the normal plane of the bodyof the aeroplane, substantially as described. 6. In a flying machine, the combination, with two superposed andnormally parallel aeroplanes, each having substantially the form of anormally flat rectangle elongated transversely to the line of flight, of upright standards connecting the edges of said aeroplanes to maintaintheir equidistance, those standards at the lateral portions of saidaeroplanes being connected therewith by flexible joints, and means forsimultaneously imparting to both lateral margins of both aeroplanes amovement about axes which are perpendicular to said margins and in theplanes of the bodies of the respective aeroplanes, and thereby movingthe lateral margins on the opposite sides of the machine into differentangular relations to the normal planes of the respective aeroplanes, themargins on the same side of the machine moving to the same angle, andthe margins on one side of the machine moving to an angle different fromthe angle to which the margins on the other side of the machine move, substantially as described. 7. In a flying machine, the combination, with an aeroplane, and meansfor simultaneously moving the lateral portions thereof into differentangular relations to the normal plane of the body of the aeroplane andto each other, so as to present to the atmosphere different angles ofincidence, of a vertical rudder, and means whereby said rudder iscaused to present to the wind that side thereof nearest the side of theaeroplane having the smaller angle of incidence and offering the leastresistance to the atmosphere, substantially as described. 8. In a flying machine, the combination, with two superposed andnormally parallel aeroplanes, upright standards connecting the edges ofsaid aeroplanes to maintain their equidistance, those standards atthe lateral portions of said aeroplanes being connected therewithby flexible joints, and means for simultaneously moving both lateralportions of both aeroplanes into different angular relations to thenormal planes of the bodies of the respective aeroplanes, the lateralportions on one side of the machine being moved to an angle differentfrom that to which the lateral portions on the other side of the machineare moved, so as to present different angles of incidence at the twosides of the machine, of a vertical rudder, and means whereby saidrudder is caused to present to the wind that side thereof nearestthe side of the aeroplanes having the smaller angle of incidence andoffering the least resistance to the atmosphere, substantially asdescribed. 9. In a flying machine, an aeroplane normally flat and elongatedtransversely to the line of flight, in combination with means forimparting to said aeroplane a helicoidal warp around an axis transverseto the line of flight and extending centrally along the body aeroplanein the direction of the elongation aeroplane, substantially asdescribed. 10. In a flying machine, two aeroplanes, each normally flat andelongated transversely to the line of flight, and upright standardsconnecting the edges of said aeroplanes to maintain their equidistance, the connections between said standards and aeroplanes being by means offlexible joints, in combination with means for simultaneously impartingto each of said aeroplanes a helicoidal warp around an axis transverseto the line of flight and extending centrally along the body of theaeroplane in the direction of the aeroplane, substantially as described. 11. In a flying machine, two aeroplanes, each normally flat andelongated transversely to the line of flight, and upright standardsconnecting the edges of said aeroplanes to maintain their equidistance, the connections between such standards and aeroplanes being by means offlexible joints, in combination with means for simultaneously impartingto each of said aeroplanes a helicoidal warp around an axis transverseto the line of flight and extending centrally along the body of theaeroplane in the direction of the elongation of the aeroplane, avertical rudder, and means whereby said rudder is caused to present tothe wind that side thereof nearest the side of the aeroplanes havingthe smaller angle of incidence and offering the least resistance to theatmosphere, substantially as described. 12. In a flying machine, the combination, with an aeroplane, of anormally flat and substantially horizontal flexible rudder, and meansfor curving said rudder rearwardly and upwardly or rearwardly anddownwardly with respect to its normal plane, substantially as described. 13. In a flying machine, the combination, with an aeroplane, of anormally flat and substantially horizontal flexible rudder pivotallymounted on an axis transverse to the line of flight near its centre, springs resisting vertical movement of the front edge of said rudder, and means for moving the rear edge of said rudder, above or below thenormal plane thereof, substantially as described. 14. A flying machine comprising superposed connected aeroplanes meansfor moving the opposite lateral portions of said aeroplanes to differentangles to the normal planes thereof, a vertical rudder, means for movingsaid vertical rudder toward that side of the machine presenting thesmaller angle of incidence and the least resistance to the atmosphere, and a horizontal rudder provided with means for presenting its upperor under surface to the resistance of the atmosphere, substantially asdescribed. 15. A flying machine comprising superposed connected aeroplanes, meansfor moving the opposite lateral portions of said aeroplanes to differentangles to the normal planes thereof, a vertical rudder, means for movingsaid vertical rudder toward that side of the machine presenting thesmaller angle of incidence and the least resistance to the atmosphere, and a horizontal rudder provided with means for presenting its upper orunder surface to the resistance of the atmosphere, said vertical rudderbeing located at the rear of the machine and said horizontal rudder atthe front of the machine, substantially as described. 16. In a flying machine, the combination, with two superposed andconnected aeroplanes, of an arm extending rearward from each aeroplane, said arms being parallel and free to swing upward at their rear ends, and a vertical rudder pivotally mounted in the rear ends of said arms, substantially as described. 17. A flying machine comprising two superposed aeroplanes, normallyflat but flexible, upright standards connecting the margins of saidaeroplanes, said standards being connected to said aeroplanes byuniversal joints, diagonal stay-wires connecting the opposite ends ofthe adjacent standards, a rope extending along the front edge of thelower aeroplane, passing through guides at the front corners thereof, and having its ends secured to the rear corners of the upper aeroplane, and a rope extending along the rear edge of the lower aeroplane, passingthrough guides at the rear corners thereof, and having its ends securedto the front corners of the upper aeroplane, substantially as described. 18. A flying machine comprising two superposed aeroplanes, normallyflat but flexible, upright standards connecting the margins of saidaeroplanes, said standards being connected to said aeroplanes byuniversal joints, diagonal stay-wires connecting the opposite ends ofthe adjacent standards, a rope extending along the front edge of thelower aeroplane, passing through guides at the front corners thereof, and having its ends secured to the rear corners of the upper aeroplane, and a rope extending along the rear edge of the lower aeroplane, passingthrough guides at the rear corners thereof, and having its ends securedto the front corners of the upper aeroplane, in combination with avertical rudder, and a tiller-rope connecting said rudder with the ropeextending along the rear edge of the lower aeroplane, substantially asdescribed. ORVILLE WRIGHT. WILBUR WRIGHT. Witnesses: Chas. E. Taylor. E. Earle Forrer. APPENDIX C Proclamation published by the French Government on balloon ascents, 1783. NOTICE TO THE PUBLIC! PARIS, 27TH AUGUST, 1783. On the Ascent of balloons or globes in the air. The one in questionhas been raised in Paris this day, 27th August, 1783, at 5 p. M. , in theChamp de Mars. A Discovery has been made, which the Government deems it right to makeknown, so that alarm be not occasioned to the people. On calculating the different weights of hot air, hydrogen gas, andcommon air, it has been found that a balloon filled with either of thetwo former will rise toward heaven till it is in equilibrium with thesurrounding air, which may not happen until it has attained a greatheight. The first experiment was made at Annonay, in Vivarais, MM. Montgolfier, the inventors; a globe formed of canvas and paper, 105 feet incircumference, filled with heated air, reached an uncalculated height. The same experiment has just been renewed in Paris before a great crowd. A globe of taffetas or light canvas covered by elastic gum and filledwith inflammable air, has risen from the Champ de Mars, and been lostto view in the clouds, being borne in a north-westerly direction. Onecannot foresee where it will descend. It is proposed to repeat these experiments on a larger scale. Anyone who shall see in the sky such a globe, which resembles 'la luneobscurcie, ' should be aware that, far from being an alarming phenomenon, it is only a machine that cannot possibly cause any harm, and which willsome day prove serviceable to the wants of society. (Signed) DE SAUVIGNY. LENOIR.