LITTLE MASTERPIECES OF SCIENCE

[Illustration: George Stephenson. ]

Little Masterpiecesof Science

Edited by George Iles

INVENTION AND DISCOVERY

_By_

Benjamin Franklin Alexander Graham BellMichael Faraday Count RumfordJoseph Henry George Stephenson

[Illustration]

NEW YORK

DOUBLEDAY, PAGE & COMPANY

1902

Copyright, 1902, by Doubleday, Page & Co. 

Copyright, 1877, by George B. Prescott

Copyright, 1896, by S. S. McClure Co. 

Copyright, 1900, by Doubleday, McClure & Co. 

PREFACE

To a good many of us the inventor is the true hero for he multiplies theworking value of life. He performs an old task with new economy, as whenhe devises a mowing-machine to oust the scythe; or he creates a servicewholly new, as when he bids a landscape depict itself on a photographicplate. He, and his twin brother, the discoverer, have eyes to read alesson that Nature has held for ages under the undiscerning gaze ofother men. Where an ordinary observer sees, or thinks he sees, diversity, a Franklin detects identity, as in the famous experiment hererecounted which proves lightning to be one and the same with a charge ofthe Leyden jar. Of a later day than Franklin, advantaged therefor by newknowledge and better opportunities for experiment, stood Faraday, thefounder of modern electric art. His work gave the world the dynamo andmotor, the transmission of giant powers, almost without toll, for twohundred miles at a bound. It is, however, in the carriage of buttrifling quantities of motion, just enough for signals, that electricitythus far has done its most telling work. Among the men who have createdthe electric telegraph Joseph Henry has a commanding place. A shortaccount of what he did, told in his own words, is here presented. Thenfollows a narrative of the difficult task of laying the first Atlanticcables, a task long scouted as impossible: it is a story which proveshow much science may be indebted to unfaltering courage, to faith inultimate triumph. 

To give speech the wings of electricity, to enable friends in Denver andNew York to converse with one another, is a marvel which onlyfamiliarity places beyond the pale of miracle. Shortly after heperfected the telephone Professor Bell described the steps which led toits construction. That recital is here reprinted. 

A recent wonder of electric art is its penetration by a photographic rayof substances until now called opaque. Professor Röntgen's account ofhow he wrought this feat forms one of the most stirring chapters in thehistory of science. Next follows an account of the telegraph as itdispenses with metallic conductors altogether, and trusts itself to thatweightless ether which brings to the eye the luminous wave. To thissucceeds a chapter which considers what electricity stands for as one ofthe supreme resources of human wit, a resource transcending even flameitself, bringing articulate speech and writing to new planes of facilityand usefulness. It is shown that the rapidity with which during a singlecentury electricity has been subdued for human service, illustrates thatprogress has leaps as well as deliberate steps, so that at last a gulf, all but infinite, divides man from his next of kin. 

At this point we pause to recall our debt to the physical philosophywhich underlies the calculations of the modern engineer. In such anexperiment as that of Count Rumford we observe how the corner-stone waslaid of the knowledge that heat is motion, and that motion underwhatever guise, as light, electricity, or what not, is equally beyondcreation or annihilation, however elusively it may glide from phase tophase and vanish from view. In the mastery of Flame for the supersedingof muscle, of breeze and waterfall, the chief credit rests with JamesWatt, the inventor of the steam engine. Beside him stands GeorgeStephenson, who devised the locomotive which by abridging space haslengthened life and added to its highest pleasures. Our volume closes bynarrating the competition which decided that Stephenson's "Rocket" wasmuch superior to its rivals, and thus opened a new chapter in thehistory of mankind. 

GEORGE ILES. 

CONTENTS

 FRANKLIN, BENJAMIN

 LIGHTNING IDENTIFIED WITH ELECTRICITY

 Franklin explains the action of the Leyden phial or jar. Suggests lightning-rods. Sends a kite into the clouds during a thunderstorm; through the kite-string obtains a spark of lightning which throws into divergence the loose fibres of the string, just as an ordinary electrical discharge would do. 3

 FARADAY, MICHAEL

 PREPARING THE WAY FOR THE ELECTRIC DYNAMO AND MOTOR

 Notices the inductive effect in one coil when the circuit in a concentric coil is completed or broken. Notices similar effects when a wire bearing a current approaches another wire or recedes from it. Rotates a galvanometer needle by an electric pulse. Induces currents in coils when the magnetism is varied in their iron or steel cores. Observes the lines of magnetic force as iron filings are magnetized. A magnetic bar moved in and out of a coil of wire excites electricity therein, --mechanical motion is converted into electricity. Generates a current by spinning a copper plate in a horizontal plane. 7

 HENRY, JOSEPH

 INVENTION OF THE ELECTRIC TELEGRAPH

 Improves the electro-magnet of Sturgeon by insulating its wire with silk thread, and by disposing the wire in several coils instead of one. Experiments with a large electro-magnet excited by nine distinct coils. Uses a battery so powerful that electro-magnets are produced one hundred times more energetic than those of Sturgeon. Arranges a telegraphic circuit more than a mile long and at that distance sounds a bell by means of an electro-magnet. 23

 ILES, GEORGE

 THE FIRST ATLANTIC CABLES

 Forerunners at New York and Dover. Gutta-percha the indispensable insulator. Wire is used to sheathe the cables. Cyrus W. Field's project for an Atlantic cable. The first cable fails. 1858 so does the second cable 1865. A triumph of courage, 1866. The highway smoothed for successors. Lessons of the cable. 37

 BELL, ALEXANDER GRAHAM

 THE INVENTION OF THE TELEPHONE

 Indebted to his father's study of the vocal organs as they form sounds. Examines the Helmholtz method for the analysis and synthesis of vocal sounds. Suggests the electrical actuation of tuning-forks and the electrical transmission of their tones. Distinguishes intermittent, pulsatory and undulatory currents. Devises as his first articulating telephone a harp of steel rods thrown into vibration by electro-magnetism. Exhibits optically the vibrations of sound, using a preparation of a human ear: is struck by the efficiency of a slight aural membrane. Attaches a bit of clock spring to a piece of goldbeater's skin, speaks to it, an audible message is received at a distant and similar device. This contrivance improved is shown at the Centennial Exhibition, Philadelphia, 1876. At first the same kind of instrument transmitted and delivered, a message; soon two distinct instruments were invented for transmitting and for receiving. Extremely small magnets suffice. A single blade of grass forms a telephonic circuit. 57

 DAM, H. J. W. 

 PHOTOGRAPHING THE UNSEEN

 Röntgen indebted to the researches of Faraday, Clerk-Maxwell, Hertz, Lodge and Lenard. The human optic nerve is affected by a very small range in the waves that exist in the ether. Beyond the visible spectrum of common light are vibrations which have long been known as heat or as photographically active. Crookes in a vacuous bulb produced soft light from high tension electricity. Lenard found that rays from a Crookes' tube passed through substances opaque to common light. Röntgen extended these experiments and used the rays photographically, taking pictures of the bones of the hand through living flesh, and so on. 87

 ILES, GEORGE

 THE WIRELESS TELEGRAPH

 What may follow upon electric induction. Telegraphy to a moving train. The Preece induction method; its limits. Marconi's system. His precursors, Hertz, Onesti, Branly and Lodge. The coherer and the vertical wire form the essence of the apparatus. Wireless telegraphy at sea. 109

 ILES, GEORGE

 ELECTRICITY, WHAT ITS MASTERY MEANS: WITH A REVIEW AND A PROSPECT

 Electricity does all that fire ever did, does it better, and performs uncounted services impossible to flame. Its mastery means as great a forward stride as the subjugation of fire. A minor invention or discovery simply adds to human resources: a supreme conquest as of flame or electricity, is a multiplier and lifts art and science to a new plane. Growth is slow, flowering is rapid: progress at times is so quick of pace as virtually to become a leap. The mastery of electricity based on that of fire. Electricity vastly wider of range than heat: it is energy in its most available and desirable phase. The telegraph and the telephone contrasted with the signal fire. Electricity as the servant of mechanic and engineer. Household uses of the current. Electricity as an agent of research now examines Nature in fresh aspects. The investigator and the commercial exploiter render aid to one another. Social benefits of electricity, in telegraphy, in quick travel. The current should serve every city house. 125

 RUMFORD, COUNT (BENJAMIN THOMPSON)

 HEAT AND MOTION IDENTIFIED

 Observes that in boring a cannon much heat is generated: the longer the boring lasts, the more heat is produced. He argues that since heat without limit may be thus produced by motion, heat must be motion. 155

 STEPHENSON, GEORGE

 THE "ROCKET" LOCOMOTIVE AND ITS VICTORY

 Shall it be a system of stationary engines or locomotives? The two best practical engineers of the day are in favour of stationary engines. A test of locomotives is, however, proffered, and George Stephenson and his son, Robert, discuss how they may best build an engine to win the first prize. They adopt a steam blast to stimulate the draft of the furnace, and raise steam quickly in a boiler having twenty-five small fire-tubes of copper. The "Rocket" with a maximum speed of twenty-nine miles an hour distances its rivals. With its load of water its weight was but four and a quarter tons. 163

INVENTION AND DISCOVERY

FRANKLIN IDENTIFIES LIGHTNING WITH ELECTRICITY

 [From Franklin's Works, edited in ten volumes by John Bigelow, Vol. I, pages 276-281, copyright by G. P. Putnam's Sons, New York. ]

Dr. Stuber, the author of the first continuation of Franklin's life, gives this account of the electrical experiments of Franklin:--

"His observations he communicated, in a series of letters, to his friendCollinson, the first of which is dated March 28, 1747. In these he showsthe power of points in drawing and throwing off the electrical matter, which had hitherto escaped the notice of electricians. He also made thegrand discovery of a _plus_ and _minus_, or of a _positive_ and_negative_ state of electricity. We give him the honour of this withouthesitation; although the English have claimed it for their countryman, Dr. Watson. Watson's paper is dated January 21, 1748; Franklin's July11, 1747, several months prior. Shortly after Franklin, from hisprinciples of the _plus_ and _minus_ state, explained in a satisfactorymanner the phenomena of the Leyden phial, first observed by Mr. Cuneus, or by Professor Muschenbroeck, of Leyden, which had much perplexedphilosophers. He showed clearly that when charged the bottle containedno more electricity than before, but that as much was taken from oneside as thrown on the other; and that to discharge it nothing wasnecessary but to produce a communication between the two sides by whichthe equilibrium might be restored, and that then no signs of electricitywould remain. He afterwards demonstrated by experiments that theelectricity did not reside in the coating as had been supposed, but inthe pores of the glass itself. After the phial was charged he removedthe coating, and found that upon applying a new coating the shock mightstill be received. In the year 1749, he first suggested his idea ofexplaining the phenomena of thunder gusts and of _aurora borealis_ uponelectric principles. He points out many particulars in which lightningand electricity agree; and he adduces many facts, and reasonings fromfacts, in support of his positions. 

"In the same year he conceived the astonishingly bold and grand idea ofascertaining the truth of his doctrine by actually drawing down thelightning, by means of sharp pointed iron rods raised into the regionsof the clouds. Even in this uncertain state his passion to be useful tomankind displayed itself in a powerful manner. Admitting the identity ofelectricity and lightning, and knowing the power of points in repellingbodies charged with electricity, and in conducting fires silently andimperceptibly, he suggested the idea of securing houses, ships and thelike from being damaged by lightning, by erecting pointed rods thatshould rise some feet above the most elevated part, and descend somefeet into the ground or water. The effect of these he concluded would beeither to prevent a stroke by repelling the cloud beyond the strikingdistance or by drawing off the electrical fire which it contained; or, if they could not effect this they would at least conduct the electricalmatter to the earth without any injury to the building. 

"It was not until the summer of 1752 that he was enabled to complete hisgrand and unparalleled discovery by experiment. The plan which he hadoriginally proposed was, to erect, on some high tower or elevated place, a sentry-box from which should rise a pointed iron rod, insulated bybeing fixed in a cake of resin. Electrified clouds passing over thiswould, he conceived, impart to it a portion of their electricity whichwould be rendered evident to the senses by sparks being emitted when akey, the knuckle, or other conductor, was presented to it. Philadelphiaat this time afforded no opportunity of trying an experiment of thiskind. While Franklin was waiting for the erection of a spire, itoccurred to him that he might have more ready access to the region ofclouds by means of a common kite. He prepared one by fastening two crosssticks to a silk handkerchief, which would not suffer so much from therain as paper. To the upright stick was affixed an iron point. Thestring was, as usual, of hemp, except the lower end, which was silk. Where the hempen string terminated, a key was fastened. With thisapparatus, on the appearance of a thundergust approaching, he went outinto the commons, accompanied by his son, to whom alone he communicatedhis intentions, well knowing the ridicule which, too generally for theinterest of science, awaits unsuccessful experiments in philosophy. Heplaced himself under a shed, to avoid the rain; his kite was raised, athunder-cloud passed over it, no sign of electricity appeared. He almostdespaired of success, when suddenly he observed the loose fibres of hisstring to move towards an erect position. He now presented his knuckleto the key and received a strong spark. How exquisite must hissensations have been at this moment! On his experiment depended the fateof his theory. If he succeeded, his name would rank high among those whohad improved science; if he failed, he must inevitably be subjected tothe derision of mankind, or, what is worse, their pity, as awell-meaning man, but a weak, silly projector. The anxiety with which helooked for the result of his experiment may easily be conceived. Doubtsand despair had begun to prevail, when the fact was ascertained, in soclear a manner, that even the most incredulous could no longer withholdtheir assent. Repeated sparks were drawn from the key, a phial wascharged, a shock given, and all the experiments made which are usuallyperformed with electricity. "

FARADAY'S DISCOVERIES LEADING UP TO THE ELECTRIC DYNAMO AND MOTOR

 [Michael Faraday was for many years Professor of Natural Philosophy at the Royal Institution, London, where his researches did more to subdue electricity to the service of man than those of any other physicist who ever lived. "Faraday as a Discoverer, " by Professor John Tyndall (his successor) depicts a mind of the rarest ability and a character of the utmost charm. This biography is published by D. Appleton & Co. , New York: the extracts which follow are from the third chapter. ]

In 1831 we have Faraday at the climax of his intellectual strength, forty years of age, stored with knowledge and full of original power. Through reading, lecturing, and experimenting, he had become thoroughlyfamiliar with electrical science: he saw where light was needed andexpansion possible. The phenomena of ordinary electric inductionbelonged, as it were, to the alphabet of his knowledge: he knew thatunder ordinary circumstances the presence of an electrified body wassufficient to excite, by induction, an unelectrified body. He knew thatthe wire which carried an electric current was an electrified body, andstill that all attempts had failed to make it excite in other wires astate similar to its own. 

What was the reason of this failure? Faraday never could work from theexperiments of others, however clearly described. He knew well that fromevery experiment issues a kind of radiation, luminous, in differentdegrees to different minds, and he hardly trusted himself to reason uponan experiment that he had not seen. In the autumn of 1831 he began torepeat the experiments with electric currents, which, up to that time, had produced no positive result. And here, for the sake of youngerinquirers, if not for the sake of us all, it is worth while to dwell fora moment on a power which Faraday possessed in an extraordinary degree. He united vast strength with perfect flexibility. His momentum was thatof a river, which combines weight and directness with the ability toyield to the flexures of its bed. The intentness of his vision in anydirection did not apparently diminish his power of perception in otherdirections; and when he attacked a subject, expecting results, he hadthe faculty of keeping his mind alert, so that results different fromthose which he expected should not escape him through pre-occupation. 

He began his experiments "on the induction of electric currents" bycomposing a helix of two insulated wires, which were wound side by sideround the same wooden cylinder. One of these wires he connected with avoltaic battery of ten cells, and the other with a sensitivegalvanometer. When connection with the battery was made, and while thecurrent flowed, no effect whatever was observed at the galvanometer. But he never accepted an experimental result, until he had applied toit the utmost power at his command. He raised his battery from ten cellsto one hundred and twenty cells, but without avail. The current flowedcalmly through the battery wire without producing, during its flow, anysensible result upon the galvanometer. 

"During its flow, " and this was the time when an effect wasexpected--but here Faraday's power of lateral vision, separating, as itwere from the line of expectation, came into play--he noticed that afeeble movement of the needle always occurred at the moment when he madecontact with the battery; that the needle would afterwards return to itsformer position and remain quietly there unaffected by the _flowing_current. At the moment, however, when the circuit was interrupted theneedle again moved, and in a direction opposed to that observed on thecompletion of the circuit. 

This result, and others of a similar kind, led him to the conclusion"that the battery current through the one wire did in reality induce asimilar current through the other; but that it continued for an instantonly, and partook more of the nature of the electric wave from a commonLeyden jar than of the current from a voltaic battery. " The momentarycurrents thus generated were called _induced currents_, while thecurrent which generated them was called the _inducing_ current. It wasimmediately proved that the current generated at making the circuit wasalways opposed in direction to its generator, while that developed onthe rupture of the circuit coincided in direction with the inducingcurrent. It appeared as if the current on its first rush through theprimary wire sought a purchase in the secondary one, and, by a kind ofkick, impelled backward through the latter an electric wave, whichsubsided as soon as the primary current was fully established. 

Faraday, for a time, believed that the secondary wire, though quiescentwhen the primary current had been once established, was not in itsnatural condition, its return to that condition being declared by thecurrent observed at breaking the circuit. He called this hypotheticalstate of the wire the _electro-tonic state_: he afterwards abandonedthis hypothesis, but seemed to return to it in after life. The termelectro-tonic is also preserved by Professor Du Bois Reymond to expressa certain electric condition of the nerves, and Professor Clerk Maxwellhas ably defined and illustrated the hypothesis in the Tenth Volume ofthe "Transactions of the Cambridge Philosophical Society. "

The mere approach of a wire forming a closed curve to a second wirethrough which a voltaic current flowed was then shown by Faraday to besufficient to arouse in the neutral wire an induced current, opposed indirection to the inducing current; the withdrawal of the wire alsogenerated a current having the same direction as the inducing current;those currents existed only during the time of approach or withdrawal, and when neither the primary nor the secondary wire was in motion, nomatter how close their proximity might be, no induced current wasgenerated. 

Faraday has been called a purely inductive philosopher. A great deal ofnonsense is, I fear, uttered in this land of England about induction anddeduction. Some profess to befriend the one, some the other, while thereal vocation of an investigator, like Faraday, consists in theincessant marriage of both. He was at this time full of the theory ofAmpère, and it cannot be doubted that numbers of his experiments wereexecuted merely to test his deductions from that theory. Starting fromthe discovery of Oersted, the celebrated French philosopher had shownthat all the phenomena of magnetism then known might be reduced to themutual attractions and repulsions of electric currents. Magnetism hadbeen produced from electricity, and Faraday, who all his life longentertained a strong belief in such reciprocal actions, now attempted toeffect the evolution of electricity from magnetism. Round a welded ironring he placed two distinct coils of covered wire, causing the coils tooccupy opposite halves of the ring. Connecting the ends of one of thecoils with a galvanometer, he found that the moment the ring wasmagnetized, by sending a current through _the other coil_, thegalvanometer needle whirled round four or five times in succession. Theaction, as before, was that of a pulse, which vanished immediately. Oninterrupting the current, a whirl of the needle in the oppositedirection occurred. It was only during the time of magnetization ordemagnetization that these effects were produced. The induced currentsdeclared a _change_ of condition only, and they vanished the moment theact of magnetization or demagnetization was complete. 

The effects obtained with the welded ring were also obtained withstraight bars of iron. Whether the bars were magnetized by the electriccurrent, or were excited by the contact of permanent steel magnets, induced currents were always generated during the rise, and during thesubsidence of the magnetism. The use of iron was then abandoned, and thesame effects were obtained by merely thrusting a permanent steel magnetinto a coil of wire. A rush of electricity through the coil accompaniedthe insertion of the magnet; an equal rush in the opposite directionaccompanied its withdrawal. The precision with which Faraday describesthese results, and the completeness with which he defined the boundariesof his facts, are wonderful. The magnet, for example, must not be passedquite through the coil, but only half through, for if passed whollythrough, the needle is stopped as by a blow, and then he shows how thisblow results from a reversal of the electric wave in the helix. He nextoperated with the powerful permanent magnet of the Royal Society, andobtained with it, in an exalted degree, all the foregoing phenomena. 

And now he turned the light of these discoveries upon the darkestphysical phenomenon of that day. Arago had discovered in 1824, that adisk of non-magnetic metal had the power of bringing a vibratingmagnetic needle suspended over it rapidly to rest; and that on causingthe disk to rotate the magnetic needle rotated along with it. When bothwere quiescent, there was not the slightest measurable attraction orrepulsion exerted between the needle and the disk; still when in motionthe disk was competent to drag after it, not only a light needle, but aheavy magnet. The question had been probed and investigated withadmirable skill by both Arago and Ampère, and Poisson had published atheoretic memoir on the subject; but no cause could be assigned for soextraordinary an action. It had also been examined in this country bytwo celebrated men, Mr. Babbage and Sir John Herschel; but it stillremained a mystery. Faraday always recommended the suspension ofjudgment in cases of doubt. "I have always admired, " he says, "theprudence and philosophical reserve shown by M. Arago in resisting thetemptations to give a theory of the effect he had discovered, so long ashe could not devise one which was perfect in its application, and inrefusing to assent to the imperfect theories of others. " Now, however, the time for theory had come. Faraday saw mentally the rotating disk, under the operation of the magnet, flooded with his induced currents, and from the known laws of interaction between currents and magnets hehoped to deduce the motion observed by Arago. That hope he realized, showing by actual experiment that when his disk rotated currents passedthrough it, their position and direction being such as must, inaccordance with the established laws of electro-magnetic action, producethe observed rotation. 

Introducing the edge of his disk between the poles of the largehorseshoe magnet of the Royal Society, and connecting the axis and theedge of the disk, each by a wire with a galvanometer, he obtained, whenthe disk was turned round, a constant flow of electricity. The directionof the current was determined by the direction of the motion, thecurrent being reversed when the rotation was reversed. He now states thelaw which rules the production of currents in both disks and wires, andin so doing uses, for the first time, a phrase which has since becomefamous. When iron filings are scattered over a magnet, the particles ofiron arrange themselves in certain determined lines called magneticcurves. In 1831, Faraday for the first time called these curves "linesof magnetic force;" and he showed that to produce induced currentsneither approach to nor withdrawal from a magnetic source, or centre, orpole, was essential, but that it was only necessary to cut appropriatelythe lines of magnetic force. Faraday's first paper on Magneto-electricInduction, which I have here endeavoured to condense, was read beforethe Royal Society on the 24th of November, 1831. 

On January 12, 1832, he communicated to the Royal Society a second paperon "Terrestrial Magneto-electric Induction, " which was chosen as theBakerian Lecture for the year. He placed a bar of iron in a coil ofwire, and lifting the bar into the direction of the dipping needle, heexcited by this action a current in the coil. On reversing the bar, acurrent in the opposite direction rushed through the wire. The sameeffect was produced, when, on holding the helix in the line of dip, abar of iron was thrust into it. Here, however, the earth acted on thecoil through the intermediation of the bar of iron. He abandoned the barand simply set a copper-plate spinning in a horizontal plane; he knewthat the earth's lines of magnetic force then crossed the plate at anangle of about 70°. When the plate spun round, the lines of force wereintersected and induced currents generated, which produced their propereffect when carried from the plate to the galvanometer. "When the platewas in the magnetic meridian, or in any other plane coinciding with themagnetic dip, then its rotation produced no effect upon thegalvanometer. "

At the suggestion of a mind fruitful in suggestions of a profound andphilosophic character--I mean that of Sir John Herschel--Mr. Barlow, ofWoolwich, had experimented with a rotating iron shell. Mr. Christie hadalso performed an elaborate series of experiments on a rotating irondisk. Both of them had found that when in rotation the body exercised apeculiar action upon the magnetic needle, deflecting it in a mannerwhich was not observed during quiescence; but neither of them was awareat the time of the agent which produced this extraordinary deflection. They ascribed it to some change in the magnetism of the iron shell anddisk. 

But Faraday at once saw that his induced currents must come into playhere, and he immediately obtained them from an iron disk. With a hollowbrass ball, moreover, he produced the effects obtained by Mr. Barlow. Iron was in no way necessary: the only condition of success was that therotating body should be of a character to admit of the formation ofcurrents in its substance: it must, in other words, be a conductor ofelectricity. The higher the conducting power the more copious were thecurrents. He now passes from his little brass globe to the globe of theearth. He plays like a magician with the earth's magnetism. He sees theinvisible lines along which its magnetic action is exerted and sweepinghis wand across these lines evokes this new power. Placing a simple loopof wire round a magnetic needle he bends its upper portion to the west:the north pole of the needle immediately swerves to the east: he bendshis loop to the east, and the north poles moves to the west. Suspendinga common bar magnet in a vertical position, he causes it to spin roundits own axis. Its pole being connected with one end of a galvanometerwire, and its equator with the other end, electricity rushes round thegalvanometer from the rotating magnet. He remarks upon the "_singularindependence_" of the magnetism and the body of the magnet which carriesit. The steel behaves as if it were isolated from its own magnetism. 

And then his thoughts suddenly widen, and he asks himself whether therotating earth does not generate induced currents as it turns round itsaxis from west to east. In his experiment with the twirling magnet thegalvanometer wire remained at rest; one portion of the circuit was inmotion _relatively_ to _another portion_. But in the case of thetwirling planet the galvanometer wire would necessarily be carried alongwith the earth; there would be no relative motion. What must be theconsequence? Take the case of a telegraph wire with its two terminalplates dipped into the earth, and suppose the wire to lie in themagnetic meridian. The ground underneath the wire is influenced like thewire itself by the earth's rotation; if a current from south to north begenerated in the wire, a similar current from south to north would begenerated in the earth under the wire; these currents would run againstthe same terminal plates, and thus neutralize each other. 

This inference appears inevitable, but his profound vision perceived itspossible invalidity. He saw that it was at least possible that thedifference of conducting power between the earth and the wire mightgive one an advantage over the other, and that thus a residual ordifferential current might be obtained. He combined wires of differentmaterials, and caused them to act in opposition to each other, but foundthe combination ineffectual. The more copious flow in the betterconductor was exactly counterbalanced by the resistance of the worst. Still, though experiment was thus emphatic, he would clear his mind ofall discomfort by operating on the earth itself. He went to the roundlake near Kensington Palace, and stretched four hundred and eighty feetof copper wire, north and south, over the lake, causing plates solderedto the wire at its ends to dip into the water. The copper wire wassevered at the middle, and the severed ends connected with agalvanometer. No effect whatever was observed. But though quiescentwater gave no effect, moving water might. He therefore worked at LondonBridge for three days during the ebb and flow of the tide, but withoutany satisfactory result. Still he urges, "Theoretically it seems anecessary consequence, that where water is flowing there electriccurrents should be formed. If a line be imagined passing from Dover toCalais through the sea, and returning through the land, beneath thewater, to Dover, it traces out a circuit of conducting matter one partof which, when the water moves up or down the channel, is cutting themagnetic curves of the earth, while the other is relatively at rest.... There is every reason to believe that currents do run in the generaldirection of the circuit described, either one way or the other, according as the passage of the waters is up or down the channel. " Thiswas written before the submarine cable was thought of, and he onceinformed me that actual observation upon that cable had been found to bein accordance with his theoretic deduction. 

Three years subsequent to the publication of these researches, that isto say on January 29, 1835, Faraday read before the Royal Society apaper "On the influence by induction of an electric current uponitself. " A shock and spark of a peculiar character had been observed bya young man named William Jenkin, who must have been a youth of somescientific promise, but who, as Faraday once informed me, was dissuadedby his own father from having anything to do with science. Theinvestigation of the fact noticed by Mr. Jenkin led Faraday to thediscovery of the _extra current_, or the current _induced in the primarywire itself_ at the moments of making and breaking contact, thephenomena of which he described and illustrated in the beautiful andexhaustive paper referred to. 

Seven and thirty years have passed since the discovery ofmagneto-electricity; but, if we except the _extra current_, until quiterecently nothing of moment was added to the subject. Faraday entertainedthe opinion that the discoverer of a great law or principle had a rightto the "spoils"--this was his term--arising from its illustration; andguided by the principle he had discovered, his wonderful mind, aided byhis wonderful ten fingers, overran in a single autumn this vast domain, and hardly left behind him the shred of a fact to be gathered by hissuccessors. 

And here the question may arise in some minds, What is the use of itall? The answer is, that if man's intellectual nature thirsts forknowledge then knowledge is useful because it satisfies this thirst. Ifyou demand practical ends, you must, I think, expand your definition ofthe term practical, and make it include all that elevates and enlightensthe intellect, as well as all that ministers to the bodily health andcomfort of men. Still, if needed, an answer of another kind might begiven to the question "what is its use?" As far as electricity has beenapplied for medical purposes, it has been almost exclusively Faraday'selectricity. You have noticed those lines of wire which cross thestreets of London. It is Faraday's currents that speed from place toplace through these wires. Approaching the point of Dungeness, themariner sees an unusually brilliant light, and from the noble lighthouseof La Hève the same light flashes across the sea. These are Faraday'ssparks exalted by suitable machinery to sun-like splendour. At thepresent moment the Board of Trade and the Brethren of the Trinity House, as well as the Commissioners of Northern Lights, are contemplating theintroduction of the Magneto-electric Light at numerous points upon ourcoasts; and future generations will be able to refer to those guidingstars in answer to the question, what has been the practical use of thelabours of Faraday? But I would again emphatically say, that his workneeds no justification, and that if he had allowed his vision to bedisturbed by considerations regarding the practical use of hisdiscoveries, those discoveries would never have been made by him. "Ihave rather, " he writes in 1831, "been desirous of discovering new factsand new relations dependent on magneto-electric induction, than ofexalting the force of those already obtained; being assured that thelatter would find their full development hereafter. "

In 1817, when lecturing before a private society in London on theelement chlorine, Faraday thus expresses himself with reference to thisquestion of utility. "Before leaving this subject, I will point out thehistory of this substance as an answer to those who are in the habit ofsaying to every new fact, 'What is its use?' Dr. Franklin says to such, 'What is the use of an infant?' The answer of the experimentalist is, 'Endeavour to make it useful. ' When Scheele discovered this substance, it appeared to have no use; it was in its infancy and useless state, buthaving grown up to maturity, witness its powers, and see what endeavoursto make it useful have done. "

PROFESSOR JOSEPH HENRY'S INVENTION OF THE ELECTRIC TELEGRAPH

 [In 1855 the Regents of the Smithsonian Institution, Washington, D. C. , at the instance of their secretary, Professor Joseph Henry, took evidence with respect to his claims as inventor of the electric telegraph. The essential paragraphs of Professor Henry's statement are taken from the Proceedings of the Board of Regents of the Smithsonian Institution, Washington, 1857. ]

There are several forms of the electric telegraph; first, that in whichfrictional electricity has been proposed to produce sparks and motion ofpith balls at a distance. 

Second, that in which galvanism has been employed to produce signals bymeans of bubbles of gas from the decomposition of water. 

Third, that in which electro-magnetism is the motive power to producemotion at a distance; and again, of the latter there are two kinds oftelegraphs, those in which the intelligence is indicated by the motionof a magnetic needle, and those in which sounds and permanent signs aremade by the attraction of an electro-magnet. The latter is the class towhich Mr. Morse's invention belongs. The following is a brief expositionof the several steps which led to this form of the telegraph. 

The first essential fact which rendered the electro-magnetic telegraphpossible was discovered by Oersted, in the winter of 1819-'20. It isillustrated by figure 1, in which the magnetic needle is deflected bythe action of a current of galvanism transmitted through the wire A B. 

[Illustration: Fig. 1]

The second fact of importance, discovered in 1820, by Arago and Davy, isillustrated in Fig. 2. It consists in this, that while a current ofgalvanism is passing through a copper wire A B, it is magnetic, itattracts iron filings and not those of copper or brass, and is capableof developing magnetism in soft iron. 

[Illustration: Fig. 2]

The next important discovery, also made in 1820, by Ampère, was that twowires through which galvanic currents are passing in the same directionattract, and in the opposite direction, repel, each other. On this factAmpère founded his celebrated theory, that magnetism consists merely inthe attraction of electrical currents revolving at right angles to theline joining the two poles of the magnet. The magnetization of a bar ofsteel or iron, according to this theory consists in establishing withinthe metal by induction a series of electrical currents, all revolving inthe same direction at right angles to the axis or length of the bar. 

[Illustration: Fig. 3]

It was this theory which led Arago, as he states, to adopt the method ofmagnetizing sewing needles and pieces of steel wire, shown in Fig. 3. This method consists in transmitting a current of electricity through ahelix surrounding the needle or wire to be magnetised. For the purposeof insulation the needle was enclosed in a glass tube, and the severalturns of the helix were at a distance from each other to insure thepassage of electricity through the whole length of the wire, or, inother words, to prevent it from seeking a shorter passage by cuttingacross from one spire to another. The helix employed by Arago obviouslyapproximates the arrangement required by the theory of Ampère, in orderto develop by induction the magnetism of the iron. By an attentiveperusal of the original account of the experiments of Arago, it will beseen that, properly speaking, he made no electro-magnet, as has beenasserted by Morse and others; his experiments were confined to themagnetism of iron filings, to sewing needles and pieces of steel wire ofthe diameter of a millimetre, or of about the thickness of a smallknitting needle. 

[Illustration: Fig. 4]

Mr. Sturgeon, in 1825, made an important step in advance of theexperiments of Arago, and produced what is properly known as theelectro-magnet. He bent a piece of iron _wire_ into the form of ahorseshoe, covered it with varnish to insulate it, and surrounded itwith a helix, of which the spires were at a distance. When a current ofgalvanism was passed through the helix from a small battery of a singlecup the iron wire became magnetic, and continued so during the passageof the current. When the current was interrupted the magnetismdisappeared, and thus was produced the first temporary soft ironmagnet. 

The electro-magnet of Sturgeon is shown in Fig. 4. By comparing Figs. 3and 4 it will be seen that the helix employed by Sturgeon was of thesame kind as that used by Arago; instead however, of a straight steelwire inclosed in a tube of glass, the former employed a bent wire ofsoft iron. The difference in the arrangement at first sight might appearto be small, but the difference in the results produced was important, since the temporary magnetism developed in the arrangement of Sturgeonwas sufficient to support a weight of several pounds, and an instrumentwas thus produced of value in future research. 

[Illustration: Fig. 5]

The next improvement was made by myself. After reading an account of thegalvanometer of Schweigger, the idea occurred to me that a much nearerapproximation to the requirements of the theory of Ampère could beattained by insulating the conducting wire itself, instead of the rod tobe magnetized, and by covering the whole surface of the iron with aseries of coils in close contact. This was effected by insulating a longwire with silk thread, and winding this around the rod of iron in closecoils from one end to the other. The same principle was extended byemploying a still longer insulated wire, and winding several strata ofthis over the first, care being taken to insure the insulation betweeneach stratum by a covering of silk ribbon. By this arrangement the rodwas surrounded by a compound helix formed of a long wire of many coils, instead of a single helix of a few coils, (Fig. 5). 

In the arrangement of Arago and Sturgeon the several turns of wire werenot precisely at right angles to the axis of the rod, as they should be, to produce the effect required by the theory, but slightly oblique, andtherefore each tended to develop a separate magnetism not coincidentwith the axis of the bar. But in winding the wire over itself, theobliquity of the several turns compensated each other, and the resultantaction was at right angles to the bar. The arrangement then introducedby myself was superior to those of Arago and Sturgeon, first in thegreater multiplicity of turns of wire, and second in the betterapplication of these turns to the development of magnetism. The power ofthe instrument with the same amount of galvanic force, was by thisarrangement several times increased. 

The maximum effect, however, with this arrangement and a single batterywas not yet obtained. After a certain length of wire had been coiledupon the iron, the power diminished with a further increase of thenumber of turns. This was due to the increased resistance which thelonger wire offered to the conduction of electricity. Two methods ofimprovement therefore suggested themselves. The first consisted, not inincreasing the length of the coil, but in using a number of separatecoils on the same piece of iron. By this arrangement the resistance tothe conduction of the electricity was diminished and a greater quantitymade to circulate around the iron from the same battery. The secondmethod of producing a similar result consisted in increasing the numberof elements of the battery, or, in other words, the projectile force ofthe electricity, which enabled it to pass through an increased number ofturns of wire, and thus, by increasing the length of the wire, todevelop the maximum power of the iron. 

[Illustration: Fig. 6]

To test these principles on a larger scale, the experimental magnet wasconstructed, which is shown in Fig. 6. In this a number of compoundhelices were placed on the same bar, their ends left projecting, and sonumbered that they could be all united into one long helix, or variouslycombined in sets of lesser length. 

From a series of experiments with this and other magnets it was provedthat, in order to produce the greatest amount of magnetism from abattery of a single cup, a number of helices is required; but when acompound battery is used, then one long wire must be employed, makingmany turns around the iron, the length of wire and consequently thenumber of turns being commensurate with the projectile power of thebattery. 

In describing the results of my experiments, the terms _intensity_ and_quantity_ magnets were introduced to avoid circumlocution, and wereintended to be used merely in a technical sense. By the _intensity_magnet I designated a piece of soft iron, so surrounded with wire thatits magnetic power could be called into operation by an _intensity_battery, and by a _quantity_ magnet, a piece of iron so surrounded by anumber of separate coils, that its magnetism could be fully developed bya _quantity_ battery. 

I was the first to point out this connection of the two kinds of thebattery with the two forms of the magnet, in my paper in _Silliman'sJournal_, January, 1831, and clearly to state that when magnetism was tobe developed by means of a compound battery, one long coil was to beemployed, and when the maximum effect was to be produced by a singlebattery, a number of single strands were to be used. 

These steps in the advance of electro-magnetism, though small, were suchas to interest and astonish the scientific world. With the same batteryused by Mr. Sturgeon, at least a hundred times more magnetism wasproduced than could have been obtained by his experiment. Thedevelopments were considered at the time of much importance in ascientific point of view, and they subsequently furnished the means bywhich magneto-electricity, the phenomena of dia-magnetism, and themagnetic effects on polarized light were discovered. They gave rise tothe various forms of electro-magnetic machines which have sinceexercised the ingenuity of inventors in every part of the world, andwere of immediate applicability in the introduction of the magnet totelegraphic purposes. Neither the electro-magnet of Sturgeon nor anyelectro-magnet ever made previous to my investigations was applicable totransmitting power to a distance. 

The principles I have developed were properly appreciated by thescientific mind of Dr. Gale, and applied by him to operate Mr. Morse'smachine at a distance. 

Previous to my investigations the means of developing magnetism in softiron were imperfectly understood. The electro-magnet made by Sturgeon, and copied by Dana, of New York, was an imperfect quantity magnet, thefeeble power of which was developed by a single battery. It was entirelyinapplicable to a long circuit with an intensity battery, and no personpossessing the requisite scientific knowledge, would have attempted touse it in that connection after reading my paper. 

In sending a message to a distance, two circuits are employed, thefirst a long circuit through which the electricity is sent to thedistant station to bring into action the second, a short one, in whichis the local battery and magnet for working the machine. In order togive projectile force sufficient to send the power to a distance, it isnecessary to use an intensity battery in the long circuit, and inconnection with this, at the distant station, a magnet surrounded withmany turns of one long wire must be employed to receive and multiply theeffect of the current enfeebled by its transmission through the longconductor. In the local or short circuit either an intensity or aquantity magnet may be employed. If the first be used, then with it acompound battery will be required; and, therefore on account of theincreased resistance due to the greater quantity of acid, a less amountof work will be performed by a given amount of material; and, consequently, though this arrangement is practicable it is by no meanseconomical. In my original paper I state that the advantages of agreater conducting power, from using several wires in the quantitymagnet, may, in a less degree, be obtained by substituting for them onelarge wire; but in this case, on account of the greater obliquity of thespires and other causes, the magnetic effect would be less. Inaccordance with these principles, the receiving magnet, or that which isintroduced into the long circuit, consists of a horseshoe magnetsurrounded with many hundred turns of a single long wire, and isoperated with a battery of from twelve to twenty-four elements or more, while in the local circuit it is customary to employ a battery of one ortwo elements with a much thicker wire and fewer turns. 

It will, I think, be evident to the impartial reader that these wereimprovements in the electro-magnet, which first rendered it adequate tothe transmission of mechanical power to a distance; and had I omittedall allusion to the telegraph in my paper, the conscientious historianof science would have awarded me some credit, however small might havebeen the advance which I made. Arago and Sturgeon, in the accounts oftheir experiments, make no mention of the telegraph, and yet their namesalways have been and will be associated with the invention. I briefly, however, called attention to the fact of the applicability of myexperiments to the construction of the telegraph; but not being familiarwith the history of the attempts made in regard to this invention, Icalled it "Barlow's project, " while I ought to have stated that Mr. Barlow's investigation merely tended to disprove the possibility of atelegraph. 

I did not refer exclusively to the needle telegraph when, in my paper, Istated that the _magnetic_ action of a current from a trough is at leastnot sensibly diminished by passing through a long wire. This is evidentfrom the fact that the immediate experiment from which this deductionwas made was by means of an electro-magnet and not by means of a needlegalvanometer. 

[Illustration: Fig. 7]

At the conclusion of the series of experiments which I described in_Silliman's Journal_, there were two applications of the electro-magnetin my mind: one the production of a machine to be moved byelectro-magnetism, and the other the transmission of or calling intoaction power at a distance. The first was carried into execution in theconstruction of the machine described in _Silliman's Journal_, vol. Xx, 1831, and for the purpose of experimenting in regard to the second, Iarranged around one of the upper rooms in the Albany Academy a wire ofmore than a mile in length, through which I was enabled to make signalsby sounding a bell, (Fig. 7. ) The mechanical arrangement for effectingthis object was simply a steel bar, permanently magnetized, of about teninches in length, supported on a pivot, and placed with its north endbetween the two arms of a horseshoe magnet. When the latter was excitedby the current, the end of the bar thus placed was attracted by one armof the horseshoe, and repelled by the other, and was thus caused to movein a horizontal plane and its further extremity to strike a bellsuitably adjusted. 

I also devised a method of breaking a circuit, and thereby causing alarge weight to fall. It was intended to illustrate the practicabilityof calling into action a great power at a distance capable of producingmechanical effects; but as a description of this was not printed, I donot place it in the same category with the experiments of which Ipublished an account, or the facts which could be immediately deducedfrom my papers in _Silliman's Journal_. 

From a careful investigation of the history of electro-magnetism in itsconnection with the telegraph, the following facts may be established:

1. Previous to my investigations the means of developing magnetism insoft iron were imperfectly understood, and the electro-magnet which thenexisted was inapplicable to the transmission of power to a distance. 

2. I was the first to prove by actual experiment that, in order todevelop magnetic power at a distance, a galvanic battery of intensitymust be employed to project the current through the long conductor, andthat a magnet surrounded by many turns of one long wire must be used toreceive this current. 

3. I was the first actually to magnetize a piece of iron at a distance, and to call attention to the fact of the applicability of my experimentsto the telegraph. 

4. I was the first to actually sound a bell at a distance by means ofthe electro-magnet. 

5. The principles I had developed were applied by Dr. Gale to renderMorse's machine effective at a distance. 

THE FIRST ATLANTIC CABLES

GEORGE ILES

 [From "Flame, Electricity and the Camera, " copyright Doubleday, Page & Co. , New York. ]

Electric telegraphy on land has put a vast distance between itself andthe mechanical signalling of Chappé, just as the scope and availabilityof the French invention are in high contrast with the rude signal firesof the primitive savage. As the first land telegraphs joined village tovillage, and city to city, the crossing of water came in as a minorincident; the wires were readily committed to the bridges which spannedstreams of moderate width. Where a river or inlet was unbridged, or achannel was too wide for the roadway of the engineer, the questionarose, May we lay an electric wire under water? With an ordinary landline, air serves as so good a non-conductor and insulator that as a rulecheap iron may be employed for the wire instead of expensive copper. Inthe quest for non-conductors suitable for immersion in rivers, channels, and the sea, obstacles of a stubborn kind were confronted. To overcomethem demanded new materials, more refined instruments, and a completerevision of electrical philosophy. 

As far back as 1795, Francisco Salva had recommended to the Academy ofSciences, Barcelona, the covering of subaqueous wires by resin, whichis both impenetrable by water and a non-conductor of electricity. Insulators, indeed, of one kind and another, were common enough, buteach of them was defective in some quality indispensable for success. Neither glass nor porcelain is flexible, and therefore to lay acontinuous line of one or the other was out of the question. Resin andpitch were even more faulty, because extremely brittle and friable. Whatof such fibres as hemp or silk, if saturated with tar or some other goodnon-conductor? For very short distances under still water they servedfairly well, but any exposure to a rocky beach with its chafing action, any rub by a passing anchor, was fatal to them. What the copper wireneeded was a covering impervious to water, unchangeable in compositionby time, tough of texture, and non-conducting in the highest degree. Fortunately all these properties are united in gutta-percha: they existin nothing else known to art. Gutta-percha is the hardened juice of alarge tree (_Isonandra gutta_) common in the Malay Archipelago; it istough and strong, easily moulded when moderately heated. In comparisonwith copper it is but one 60, 000, 000, 000, 000, 000, 000th as conductive. Aswithout gutta-percha there could be no ocean telegraphy, it is worthwhile recalling how it came within the purview of the electricalengineer. 

In 1843 José d'Almeida, a Portuguese engineer, presented to the RoyalAsiatic Society, London, the first specimens of gutta-percha brought toEurope. A few months later, Dr. W. Montgomerie, a surgeon, gave otherspecimens to the Society of Arts, of London, which exhibited them; butit was four years before the chief characteristic of the gum wasrecognized. In 1847 Mr. S. T. Armstrong of New York, during a visit toLondon, inspected a pound or two of gutta-percha, and found it to betwice as good a non-conductor as glass. The next year, through hisinstrumentality, a cable covered with this new insulator was laidbetween New York and Jersey City; its success prompted Mr Armstrong tosuggest that a similarly protected cable be submerged between Americaand Europe. Eighteen years of untiring effort, impeded by the errorsinevitable to the pioneer, stood between the proposal and itsfulfilment. In 1848 the Messrs. Siemens laid under water in the port ofKiel a wire covered with seamless gutta-percha, such as, beginning with1847, they had employed for subterranean conductors. This particularwire was not used for telegraphy, but formed part of a submarine-minesystem. In 1849 Mr. C. V. Walker laid an experimental line in theEnglish Channel; he proved the possibility of signalling for two milesthrough a wire covered with gutta-percha, and so prepared the way for aventure which joined the shores of France and England. 

[Illustration: Fig. 58. --Calais-Dover cable, 1851]

In 1850 a cable twenty-five miles in length was laid from Dover toCalais, only to prove worthless from faulty insulation and the lack ofarmour against dragging anchors and fretting rocks. In 1851 theexperiment was repeated with success. The conductor now was not a singlewire of copper, but four wires, wound spirally, so as to combinestrength with flexibility; these were covered with gutta-percha andsurrounded with tarred hemp. As a means of imparting additionalstrength, ten iron wires were wound round the hemp--a feature which hasbeen copied in every subsequent cable (Fig. 58). The engineers were fastlearning the rigorous conditions of submarine telegraphy; in itsessentials the Dover-Calais line continues to be the type of deep-seacables to-day. The success of the wire laid across the British Channelincited other ventures of the kind. Many of them, through carelessconstruction or unskilful laying, were utter failures. At last, in 1855, a submarine line 171 miles in length gave excellent service, as itunited Varna with Constantinople; this was the greatest length ofsatisfactory cable until the submergence of an Atlantic line. 

In 1854 Cyrus W. Field of New York opened a new chapter in electricalenterprise as he resolved to lay a cable between Ireland andNewfoundland, along the shortest line that joins Europe to America. Hechose Valentia and Heart's Content, a little more than 1, 600 milesapart, as his termini, and at once began to enlist the co-operation ofhis friends. Although an unfaltering enthusiast when once his great ideahad possession of him, Mr. Field was a man of strong common sense. Fromfirst to last he went upon well-ascertained facts; when he failed he didso simply because other facts, which he could not possibly know, had tobe disclosed by costly experience. Messrs. Whitehouse and Bright, electricians to his company, were instructed to begin a preliminaryseries of experiments. They united a continuous stretch of wires laidbeneath land and water for a distance of 2, 000 miles, and found thatthrough this extraordinary circuit they could transmit as many as foursignals per second. They inferred that an Atlantic cable would offer butlittle more resistance, and would therefore be electrically workable andcommercially lucrative. 

In 1857 a cable was forthwith manufactured, divided in halves, andstowed in the holds of the _Niagara_ of the United States navy, and the_Agamemnon_ of the British fleet. The _Niagara_ sailed from Ireland; thesister ship proceeded to Newfoundland, and was to meet her in mid-ocean. When the _Niagara_ had run out 335 miles of her cable it snapped undera sudden increase of strain at the paying-out machinery; all attempts atrecovery were unavailing, and the work for that year was abandoned. Thenext year it was resumed, a liberal supply of new cable having beenmanufactured to replace the lost section, and to meet any freshemergency that might arise. A new plan of voyages was adopted: thevessels now sailed together to mid-sea, uniting there both portions ofthe cable; then one ship steamed off to Ireland, the other to theNewfoundland coast. Both reached their destinations on the same day, August 5, 1858, and, feeble and irregular though it was, an electricpulse for the first time now bore a message from hemisphere tohemisphere. After 732 despatches had passed through the wire it becamesilent forever. In one of these despatches from London, the War Officecountermanded the departure of two regiments about to leave Canada forEngland, which saved an outlay of about $250, 000. This widely quotedfact demonstrated with telling effect the value of cable telegraphy. 

Now followed years of struggle which would have dismayed any lessresolute soul than Mr. Field. The Civil War had broken out, with itsperils to the Union, its alarms and anxieties for every American heart. But while battleships and cruisers were patrolling the coast from Maineto Florida, and regiments were marching through Washington on their wayto battle, there was no remission of effort on the part of the greatprojector. 

Indeed, in the misunderstandings which grew out of the war, and that atone time threatened international conflict, he plainly saw how a cablewould have been a peace-maker. A single word of explanation through itswire, and angry feelings on both sides of the ocean would have beenallayed at the time of the _Trent_ affair. In this conviction he wasconfirmed by the English press; the London _Times_ said: "We nearly wentto war with America because we had no telegraph across the Atlantic. " In1859 the British government had appointed a committee of eminentengineers to inquire into the feasibility of an Atlantic telegraph, witha view to ascertaining what was wanting for success, and with theintention of adding to its original aid in case the enterprise wererevived. In July, 1863, this committee presented a report entirelyfavourable in its terms, affirming "that a well-insulated cable, properly protected, of suitable specific gravity, made with care, testedunder water throughout its progress with the best-known apparatus, andpaid into the ocean with the most improved machinery, possesses everyprospect of not only being successfully laid in the first instance, butmay reasonably be relied upon to continue for many years in an efficientstate for the transmission of signals. "

Taking his stand upon this endorsement, Mr. Field now addressed himselfto the task of raising the large sum needed to make and lay a new cablewhich should be so much better than the old ones as to reward its ownerswith triumph. He found his English friends willing to venture thecapital required, and without further delay the manufacture of a newcable was taken in hand. In every detail the recommendations of theScientific Committee were carried out to the letter, so that the cableof 1865 was incomparably superior to that of 1858. First, the centralcopper wire, which was the nerve along which the lightning was to run, was nearly three times larger than before. The old conductor was astrand consisting of seven fine wires, six laid around one, and weighedbut 107 pounds to the mile. The new was composed of the same number ofwires, but weighed 300 pounds to the mile. It was made of the finestcopper obtainable. 

To secure insulation, this conductor was first embedded in Chatterton'scompound, a preparation impervious to water, and then covered with fourlayers of gutta-percha, which were laid on alternately with four thinlayers of Chatterton's compound. The old cable had but three coatings ofgutta-percha, with nothing between. Its entire insulation weighed but261 pounds to the mile, while that of the new weighed 400 pounds. [1] Theexterior wires, ten in number, were of Bessemer steel, each separatelywound in pitch-soaked hemp yarn, the shore ends specially protected bythirty-six wires girdling the whole. Here was a combination of thetenacity of steel with much of the flexibility of rope. The insulationof the copper was so excellent as to exceed by a hundredfold that of thecore of 1858--which, faulty though it was, had, nevertheless, sufficedfor signals. So much inconvenience and risk had been encountered individing the task of cable-laying between two ships that this time itwas decided to charter a single vessel, the _Great Eastern_, which, fortunately, was large enough to accommodate the cable in an unbrokenlength. Foilhommerum Bay, about six miles from Valentia, was selected asthe new Irish terminus by the company. Although the most anxious carewas exercised in every detail, yet, when 1, 186 miles had been laid, thecable parted in 11, 000 feet of water, and although thrice it wasgrappled and brought toward the surface, thrice it slipped off thegrappling hooks and escaped to the ocean floor. Mr. Field was obliged toreturn to England and face as best he might the men whose capital lay atthe bottom of the sea--perchance as worthless as so much Atlantic ooze. With heroic persistence he argued that all difficulties would yield to arenewed attack. There must be redoubled precautions and vigilance neverfor a moment relaxed. Everything that deep-sea telegraphy has sinceaccomplished was at that moment daylight clear to his prophetic view. Never has there been a more signal example of the power of enthusiasm tostir cold-blooded men of business; never has there been a more strikingillustration of how much science may depend for success upon theintelligence and the courage of capital. Electricians might have gone onperfecting exquisite apparatus for ocean telegraphy, or indicated theweak points in the comparatively rude machinery which made and laid thecable, yet their exertions would have been wasted if men of wealth hadnot responded to Mr. Field's renewed appeal for help. Thrice these menhad invested largely, and thrice disaster had pursued their ventures;nevertheless they had faith surviving all misfortunes for a fourthattempt. 

In 1866 a new company was organized, for two objects: first, to recoverthe cable lost the previous year and complete it to the American shore;second, to lay another beside it in a parallel course. The _GreatEastern_ was again put in commission, and remodelled in accordance withthe experience of her preceding voyage. This time the exterior wires ofthe cable were of galvanized iron, the better to resist corrosion. Thepaying-out machinery was reconstructed and greatly improved. On July 13, 1866, the huge steamer began running out her cable twenty-five milesnorth of the line struck out during the expedition of 1865; she arrivedwithout mishap in Newfoundland on July 27, and electrical communicationwas re-established between America and Europe. The steamer now returnedto the spot where she had lost the cable a few months before; aftereighteen days' search it was brought to the deck in good order. Unionwas effected with the cable stowed in the tanks below, and the prow ofthe vessel was once more turned to Newfoundland. On September 8th thissecond cable was safely landed at Trinity Bay. Misfortunes now were atan end; the courage of Mr. Field knew victory at last; the highesthonors of two continents were showered upon him. 

 'Tis not the grapes of Canaan that repay, But the high faith that failed not by the way. 

[Illustration: Fig. 59. --Commercial cable, 1894]

What at first was as much a daring adventure as a business enterprisehas now taken its place as a task no more out of the common thanbuilding a steamship, or rearing a cantilever bridge. Given its price, which will include too moderate a profit to betray any expectation offailure, and a responsible firm will contract to lay a cable across thePacific itself. In the Atlantic lines the uniformly low temperature ofthe ocean floor (about 4° C. ), and the great pressure of thesuperincumbent sea, co-operate in effecting an enormous enhancement bothin the insulation and in the carrying capacity of the wire. As anexample of recent work in ocean telegraphy let us glance at the cablelaid in 1894, by the Commercial Cable Company of New York. It unitesCape Canso, on the northeastern coast of Nova Scotia, to Waterville, onthe southwestern coast of Ireland. The central portion of this cablemuch resembles that of its predecessor in 1866. Its exterior armour ofsteel wires is much more elaborate. The first part of Fig. 59 shows thedetails of manufacture: the central copper core is covered withgutta-percha, then with jute, upon which the steel wires are spirallywound, followed by a strong outer covering. For the greatest depths atsea, type _A_ is employed for a total length of 1, 420 miles; thediameter of this part of the cable is seven-eighths of an inch. As thewater lessens in depth the sheathing increases in size until thediameter of the cable becomes one and one-sixteenth inches for 152miles, as type _B_. The cable now undergoes a third enlargement, andthen its fourth and last proportions are presented as it touches theshore, for a distance of one and three-quarter miles, where type _C_ hasa diameter of two and one-half inches. The weights of material used inthis cable are: copper wire, 495 tons; gutta-percha, 315 tons; juteyarn, 575 tons; steel wire, 3, 000 tons; compound and tar, 1, 075 tons;total, 5, 460 tons. The telegraph-ship _Faraday_, specially designed forcable-laying, accomplished the work without mishap. 

Electrical science owes much to the Atlantic cables, in particular tothe first of them. At the very beginning it banished the idea thatelectricity as it passes through metallic conductors has anything likeits velocity through free space. It was soon found, as ProfessorMendenhall says, "that it is no more correct to assign a definitevelocity to electricity than to a river. As the rate of flow of a riveris determined by the character of its bed, its gradient, and othercircumstances, so the velocity of an electric current is found to dependon the conditions under which the flow takes place. "[2] Mile for milethe original Atlantic cable had twenty times the retarding effect of agood aerial line; the best recent cables reduce this figure by nearlyone-half. 

In an extreme form, this slowing down reminds us of the obstruction oflight as it enters the atmosphere of the earth, of the furtherimpediment which the rays encounter if they pass from the air into thesea. In the main the causes which hinder a pulse committed to a cableare two: induction, and the electrostatic capacity of the wire, that is, the capacity of the wire to take up a charge of its own, just as if itwere the metal of a Leyden jar. 

Let us first consider induction. As a current takes its way through thecopper core it induces in its surroundings a second and opposingcurrent. For this the remedy is one too costly to be applied. Were acable manufactured in a double line, as in the best telephonic circuits, induction, with its retarding and quenching effects, would beneutralized. Here the steel wire armour which encircles the cable playsan unwelcome part. Induction is always proportioned to the conductivityof the mass in which it appears; as steel is an excellent conductor, thearmour of an ocean cable, close as it is to the copper core, has inducedin it a current much stronger, and therefore more retarding, than if thesteel wire were absent. 

A word now as to the second difficulty in working beneath the sea--thatdue to the absorbing power of the line itself. An Atlantic cable, likeany other extended conductor, is virtually a long, cylindrical Leydenjar, the copper wire forming the inner coat, and its surroundings theouter coat. Before a signal can be received at the distant terminus thewire must first be charged. The effect is somewhat like transmitting asignal through water which fills a rubber tube; first of all the tubeis distended, and its compression, or secondary effect, really transmitsthe impulse. A remedy for this is a condenser formed of alternate sheetsof tin-foil and mica, _C_, connected with the battery, _B_, so as tobalance the electric charge of the cable wire (Fig. 60). In the firstAtlantic line an impulse demanded one-seventh of a second for itsjourney. This was reduced when Mr. Whitehouse made the capital discoverythat the speed of a signal is increased threefold when the wire isalternately connected with the zinc and copper poles of the battery. SirWilliam Thomson ascertained that these successive pulses are mosteffective when of proportioned lengths. He accordingly devised anautomatic transmitter which draws a duly perforated slip of paper undera metallic spring connected with the cable. To-day 250 to 300 lettersare sent per minute instead of fifteen, as at first. 

[Illustration: Fig. 60. --Condenser]

In many ways a deep-sea cable exaggerates in an instructive manner thephenomena of telegraphy over long aerial lines. The two ends of a cablemay be in regions of widely diverse electrical potential, or pressure, just as the readings of the barometer at these two places may differmuch. If a copper wire were allowed to offer itself as a gatelessconductor it would equalize these variations of potential with seriousinjury to itself. Accordingly the rule is adopted of working the cablenot directly, as if it were a land line, but indirectly throughcondensers. As the throb sent through such apparatus is but momentary, the cable is in no risk from the strong currents which would coursethrough it if it were permitted to be an open channel. 

[Illustration: Fig. 61. --Reflecting galvanometer L, lamp; N, moving spotof light reflected from mirror]

A serious error in working the first cables was in supposing that theyrequired strong currents as in land lines of considerable length. Thevery reverse is the fact. Mr. Charles Bright, in _Submarine Telegraphs_, says:

"Mr. Latimer Clark had the conductor of the 1865 and 1866 lines joinedtogether at the Newfoundland end, thus forming an unbroken length of3, 700 miles in circuit. He then placed some sulphuric acid in a verysmall silver thimble, with a fragment of zinc weighing a grain or two. By this primitive agency he succeeded in conveying signals through twicethe breadth of the Atlantic Ocean in little more than a second of timeafter making contact. The deflections were not of a dubious character, but full and strong, from which it was manifest than an even smallerbattery would suffice to produce somewhat similar effects. "

[Illustration: Fig. 62. --Siphon recorder]

At first in operating the Atlantic cable a mirror galvanometer wasemployed as a receiver. The principle of this receiver has often beenillustrated by a mischievous boy as, with a slight and almostimperceptible motion of his hand, he has used a bit of looking-glass todart a ray of reflected sunlight across a wide street or a large room. On the same plan, the extremely minute motion of a galvanometer, as itreceives the successive pulsations of a message, is magnified by aweightless lever of light so that the words are easily read by anoperator (Fig. 61). This beautiful invention comes from the hands of SirWilliam Thomson [now Lord Kelvin], who, more than any other electrician, has made ocean telegraphy an established success. 

[Illustration: Fig. 63. --Siphon record. "Arrived yesterday"]

In another receiver, also of his design, the siphon recorder, he beganby taking advantage of the fact, observed long before by Bose, that acharge of electricity stimulates the flow of a liquid. In its originalform the ink-well into which the siphon dipped was insulated and chargedto a high voltage by an influence-machine; the ink, powerfully repelled, was spurted from the siphon point to a moving strip of paper beneath(Fig. 62). It was afterward found better to use a delicate mechanicalshaker which throws out the ink in minute drops as the cable currentgently sways the siphon back and forth (Fig. 63). 

Minute as the current is which suffices for cable telegraphy, it isessential that the metallic circuit be not only unbroken, but unimpairedthroughout. No part of his duty has more severely taxed the resources ofthe electrician than to discover the breaks and leaks in his oceancables. One of his methods is to pour electricity as it were, into abroken wire, much as if it were a narrow tube, and estimate the lengthof the wire (and consequently the distance from shore to the defect orbreak) by the quantity of current required to fill it. 

FOOTNOTES:

[1] Henry M. Field, "History of the Atlantic Telegraph. " New York:Scribner, 1866. 

[2] "A Century of Electricity. " Boston, Houghton, Mifflin & Co. , 1887. 

BELL'S TELEPHONIC RESEARCHES

 [From "Bell's Electric Speaking Telephones, " by George B. Prescott, copyright by D Appleton & Co. , New York, 1884]

In a lecture delivered before the Society of Telegraph Engineers, inLondon, October 31, 1877, Prof. A. G. Bell gave a history of hisresearches in telephony, together with the experiments that he was ledto undertake in his endeavours to produce a practical system of multipletelegraphy, and to realize also the transmission of articulate speech. After the usual introduction, Professor Bell said in part:

It is to-night my pleasure, as well as duty, to give you some account ofthe telephonic researches in which I have been so long engaged. Manyyears ago my attention was directed to the mechanism of speech by myfather, Alexander Melville Bell, of Edinburgh, who has made a life-longstudy of the subject. Many of those present may recollect the inventionby my father of a means of representing, in a wonderfully accuratemanner, the positions of the vocal organs in forming sounds. Together wecarried on quite a number of experiments, seeking to discover thecorrect mechanism of English and foreign elements of speech, and Iremember especially an investigation in which we were engagedconcerning the musical relations of vowel sounds. When vocal sounds arewhispered, each vowel seems to possess a particular pitch of its own, and by whispering certain vowels in succession a musical scale can bedistinctly perceived. Our aim was to determine the natural pitch of eachvowel; but unexpected difficulties made their appearance, for many ofthe vowels seemed to possess a double pitch--one due, probably, to theresonance of the air in the mouth, and the other to the resonance of theair contained in the cavity behind the tongue, comprehending the pharynxand larynx. 

I hit upon an expedient for determining the pitch, which, at that time, I thought to be original with myself. It consisted in vibrating a tuningfork in front of the mouth while the positions of the vocal organs forthe various vowels were silently taken. It was found that each vowelposition caused the reinforcement of some particular fork or forks. 

I wrote an account of these researches to Mr. Alex. J. Ellis, of London. In reply, he informed me that the experiments related had already beenperformed by Helmholtz, and in a much more perfect manner than I haddone. Indeed, he said that Helmholtz had not only analyzed the vowelsounds into their constituent musical elements, but had actuallyperformed the synthesis of them. 

He had succeeded in producing, artificially, certain of the vowel soundsby causing tuning forks of different pitch to vibrate simultaneously bymeans of an electric current. Mr. Ellis was kind enough to grant me aninterview for the purpose of explaining the apparatus employed byHelmholtz in producing these extraordinary effects, and I spent thegreater part of a delightful day with him in investigating the subject. At that time, however, I was too slightly acquainted with the laws ofelectricity fully to understand the explanations given; but theinterview had the effect of arousing my interest in the subjects ofsound and electricity, and I did not rest until I had obtainedpossession of a copy of Helmholtz's great work "The Theory of Tone, " andhad attempted, in a crude and imperfect manner, it is true, to reproducehis results. While reflecting upon the possibilities of the productionof sound by electrical means, it struck me that the principle ofvibrating a tuning fork by the intermittent attraction of anelectro-magnet might be applied to the electrical production of music. 

I imagined to myself a series of tuning forks of different pitches, arranged to vibrate automatically in the manner shown by Helmholtz--eachfork interrupting, at every vibration, a voltaic current--and thethought occurred, Why should not the depression of a key like that of apiano direct the interrupted current from any one of these forks, through a telegraph wire, to a series of electro-magnets operating thestrings of a piano or other musical instrument, in which case a personmight play the tuning fork piano in one place and the music be audiblefrom the electro-magnetic piano in a distant city. 

The more I reflected upon this arrangement the more feasible did it seemto me; indeed, I saw no reason why the depression of a number of keys atthe tuning fork end of the circuit should not be followed by the audibleproduction of a full chord from the piano in the distant city, eachtuning fork affecting at the receiving end that string of the piano withwhich it was in unison. At this time the interest which I felt inelectricity led me to study the various systems of telegraphy in use inthis country and in America. I was much struck with the simplicity ofthe Morse alphabet, and with the fact that it could be read by sound. Instead of having the dots and dashes recorded on paper, the operatorswere in the habit of observing the duration of the click of theinstruments, and in this way were enabled to distinguish by ear thevarious signals. 

It struck me that in a similar manner the duration of a musical notemight be made to represent the dot or dash of the telegraph code, sothat a person might operate one of the keys of the tuning fork pianoreferred to above, and the duration of the sound proceeding from thecorresponding string of the distant piano be observed by an operatorstationed there. It seemed to me that in this way a number of distincttelegraph messages might be sent simultaneously from the tuning forkpiano to the other end of the circuit by operators, each manipulating adifferent key of the instrument. These messages would be read byoperators stationed at the distant piano, each receiving operatorlistening for signals for a certain definite pitch, and ignoring allothers. In this way could be accomplished the simultaneous transmissionof a number of telegraphic messages along a single wire, the numberbeing limited only by the delicacy of the listener's ear. The idea ofincreasing the carrying power of a telegraph wire in this way tookcomplete possession of my mind, and it was this practical end that I hadin view when I commenced my researches in electric telephony. 

[Illustration: Fig. 1]

In the progress of science it is universally found that complexity leadsto simplicity, and in narrating the history of scientific research it isoften advisable to begin at the end. 

In glancing back over my own researches, I find it necessary todesignate, by distinct names, a variety of electrical currents by meansof which sounds can be produced, and I shall direct your attention toseveral distinct species of what may be termed telephonic currents ofelectricity. In order that the peculiarities of these currents may beclearly understood, I shall project upon the screen a graphicalillustration of the different varieties. 

The graphical method of representing electrical currents shown in Fig. 1is the best means I have been able to devise of studying, in an accuratemanner, the effects produced by various forms of telephonic apparatus, and it has led me to the conception of that peculiar species oftelephonic current, here designated as _undulatory_, which has renderedfeasible the artificial production of articulate speech by electricalmeans. 

A horizontal line (_g g'_) is taken as the zero of current, and impulsesof positive electricity are represented above the zero line, andnegative impulses below it, or _vice versa_. 

The vertical thickness of any electrical impulse (_b_ or _d_), measuredfrom the zero line, indicates the intensity of the electrical current atthe point observed; and the horizontal extension of the electric line(_b_ or _d_) indicates the duration of the impulse. 

Nine varieties of telephonic currents may be distinguished, but it willonly be necessary to show you six of these. The three primary varietiesdesignated as intermittent, pulsatory and undulatory, are represented inlines 1, 2 and 3. 

Sub-varieties of these can be distinguished as direct or reversedcurrents, according as the electrical impulses are all of one kind orare alternately positive and negative. Direct currents may stillfurther be distinguished as positive or negative, according as theimpulses are of one kind or of the other. 

An intermittent current is characterized by the alternate presence andabsence of electricity upon the circuit. 

A pulsatory current results from sudden or instantaneous changes in theintensity of a continuous current; and

An undulatory current is a current of electricity, the intensity ofwhich varies in a manner proportional to the velocity of the motion of aparticle of air during the production of a sound: thus the curverepresenting graphically the undulatory current for a simple musicalnote is the curve expressive of a simple pendulous vibration--that is, asinusoidal curve. 

And here I may remark, that, although the conception of the undulatorycurrent of electricity is entirely original with myself, methods ofproducing sound by means of intermittent and pulsatory currents havelong been known. For instance, it was long since discovered that anelectro-magnet gives forth a decided sound when it is suddenlymagnetized or demagnetized. When the circuit upon which it is placed israpidly made and broken, a succession of explosive noises proceeds fromthe magnet. These sounds produce upon the ear the effect of a musicalnote when the current is interrupted a sufficient number of times persecond.... 

[Illustration: Fig. 2]

For several years my attention was almost exclusively directed to theproduction of an instrument for making and breaking a voltaic circuitwith extreme rapidity, to take the place of the transmitting tuning forkused in Helmholtz's researches. Without going into details, I shallmerely say that the great defects of this plan of multiple telegraphywere found to consist, first, in the fact that the receiving operatorswere required to possess a good musical ear in order to discriminate thesignals; and secondly, that the signals could only pass in one directionalong the line (so that two wires would be necessary in order tocomplete communication in both directions). The first objection was gotover by employing the device which I term a "vibratory circuit breaker, "whereby musical signals can be automatically recorded.... 

I have formerly stated that Helmholtz was enabled to produce vowelsounds artificially by combining musical tones of different pitches andintensities. His apparatus is shown in Fig. 2. Tuning forks of differentpitch are placed between the poles of electro-magnets (_a1_, _a2_, &c. ), and are kept in continuous vibration by the action of an intermittentcurrent from the fork _b_. Resonators, 1, 2, 3, etc. , are arranged so asto reinforce the sounds in a greater or less degree, according as theexterior orifices are enlarged or contracted. 

[Illustration: Fig. 3]

Thus it will be seen that upon Helmholtz's plan the tuning forksthemselves produce tones of uniform intensity, the loudness being variedby an external reinforcement; but it struck me that the same resultswould be obtained, and in a much more perfect manner, by causing thetuning forks themselves to vibrate with different degrees of amplitude. I therefore devised the apparatus shown in Fig. 3, which was my firstform of articulating telephone. In this figure a harp of steel rods isemployed, attached to the poles of a permanent magnet, N. S. When anyone of the rods is thrown into vibration an undulatory current isproduced in the coils of the electro-magnet E, and the electro-magnet E'attracts the rods of the harp H' with a varying force, throwing intovibration that rod which is in unison with that vibrating at the otherend of the circuit. Not only so, but the amplitude of vibration in theone will determine the amplitude of vibration in the other, for theintensity of the induced current is determined by the amplitude of theinducing vibration, and the amplitude of the vibration at the receivingend depends upon the intensity of the attractive impulses. When we singinto a piano, certain of the strings of the instrument are set invibration sympathetically by the action of the voice with differentdegrees of amplitude, and a sound, which is an approximation to thevowel uttered, is produced from the piano. Theory shows that, had thepiano a very much larger number of strings to the octave, the vowelsounds would be perfectly reproduced. My idea of the action of theapparatus, shown in Fig. 3, was this: Utter a sound in the neighbourhoodof the harp H, and certain of the rods would be thrown into vibrationwith different amplitudes. At the other end of the circuit thecorresponding rods of the harp H would vibrate with their properrelations of force, and the _timbre_ [characteristic quality] of thesound would be reproduced. The expense of constructing such an apparatusas that shown in figure 3 deterred me from making the attempt, and Isought to simplify the apparatus before venturing to have it made. 

[Illustration: Fig. 4]

[Illustration: Fig. 5]

[Illustration: Fig. 6]

I have before alluded to the invention by my father of a system ofphysiological symbols for representing the action of the vocal organs, and I had been invited by the Boston Board of Education to conduct aseries of experiments with the system in the Boston school for the deafand dumb. It is well known that deaf mutes are dumb merely because theyare deaf, and that there is no defect in their vocal organs toincapacitate them from utterance. Hence it was thought that my father'ssystem of pictorial symbols, popularly known as visible speech, mightprove a means whereby we could teach the deaf and dumb to use theirvocal organs and to speak. The great success of these experiments urgedupon me the advisability of devising method of exhibiting the vibrationsof sound optically, for use in teaching the deaf and dumb. For some timeI carried on experiments with the manometric capsule of Köenig and withthe phonautograph of Léon Scott. The scientific apparatus in theInstitute of Technology in Boston was freely placed at my disposal forthese experiments, and it happened that at that time a student of theInstitute of Technology, Mr. Maurey, had invented an improvement uponthe phonautograph. He had succeeded in vibrating by the voice a stylusof wood about a foot in length, which was attached to the membrane ofthe phonautograph, and in this way he had been enabled to obtainenlarged tracings upon a plane surface of smoked glass. With thisapparatus I succeeded in producing very beautiful tracings of thevibrations of the air for vowel sounds. Some of these tracings are shownin Fig. 4. I was much struck with this improved form of apparatus, andit occurred to me that there was a remarkable likeness between themanner in which this piece of wood was vibrated by the membrane of thephonautograph and the manner in which the _ossiculo_ [small bones] ofthe human ear were moved by the tympanic membrane. I determinedtherefore, to construct a phonautograph modelled still more closelyupon the mechanism of the human ear, and for this purpose I sought theassistance of a distinguished aurist in Boston, Dr. Clarence J. Blake. He suggested the use of the human ear itself as a phonautograph, insteadof making an artificial imitation of it. The idea was novel and struckme accordingly, and I requested my friend to prepare a specimen for me, which he did. The apparatus, as finally constructed, is shown in Fig. 5. The _stapes_ [inmost of the three auditory ossicles] was removed and apointed piece of hay about an inch in length was attached to the end ofthe incus [the middle of the three auditory ossicles]. Upon moisteningthe membrana tympani [membrane of the ear drum] and the ossiculæ with amixture of glycerine and water the necessary mobility of the parts wasobtained, and upon singing into the external artificial ear the piece ofhay was thrown into vibration, and tracings were obtained upon a planesurface of smoked glass passed rapidly underneath. While engaged inthese experiments I was struck with the remarkable disproportion inweight between the membrane and the bones that were vibrated by it. Itoccurred to me that if a membrane as thin as tissue paper could controlthe vibration of bones that were, compared to it, of immense size andweight, why should not a larger and thicker membrane be able to vibratea piece of iron in front of an electro-magnet, in which case thecomplication of steel rods shown in my first form of telephone, Fig. 3, could be done away with, and a simple piece of iron attached to amembrane be placed at either end of the telegraphic circuit. 

Figure 6 shows the form of apparatus that I was then employing forproducing undulatory currents of electricity for the purpose of multipletelegraphy. A steel reed, A, was clamped firmly by one extremity to theuncovered leg _h_ of an electro-magnet E, and the free end of the reedprojected above the covered leg. When the reed A was vibrated in anymechanical way the battery current was thrown into waves, and electricalundulations traversed the circuit B E W E', throwing into vibration thecorresponding reed A' at the other end of the circuit. I immediatelyproceeded to put my new idea to the test of practical experiment, andfor this purpose I attached the reed A (Fig. 7) loosely by one extremityto the uncovered pole _h_ of the magnet, and fastened the otherextremity to the centre of a stretched membrane of goldbeaters' skin_n_. I presumed that upon speaking in the neighbourhood of the membrane_n_ it would be thrown into vibration and cause the steel reed A to movein a similar manner, occasioning undulations in the electrical currentthat would correspond to the changes in the density of the air duringthe production of the sound; and I further thought that the change ofthe density of the current at the receiving end would cause the magnetthere to attract the reed A' in such a manner that it should copy themotion of the reed A, in which case its movements would occasion a soundfrom the membrane _n'_ similar in _timbre_ to that which had occasionedthe original vibration. 

[Illustration: Fig. 7]

[Illustration: Fig. 8]

The results, however, were unsatisfactory and discouraging. My friend, Mr. Thomas A. Watson, who assisted me in this first experiment, declaredthat he heard a faint sound proceed from the telephone at his end of thecircuit, but I was unable to verify his assertion. After manyexperiments, attended by the same only partially successful results, Idetermined to reduce the size and weight of the spring as much aspossible. For this purpose I glued a piece of clock spring about thesize and shape of my thumb nail, firmly to the centre of the diaphragm, and had a similar instrument at the other end (Fig. 8); we were thenenabled to obtain distinctly audible effects. I remember an experimentmade with this telephone, which at the time gave me great satisfactionand delight. One of the telephones was placed in my lecture room in theBoston University, and the other in the basement of the adjoiningbuilding. One of my students repaired to the distant telephone toobserve the effects of articulate speech, while I uttered the sentence, "Do you understand what I say?" into the telephone placed in the lecturehall. To my delight an answer was returned through the instrumentitself, articulate sounds proceeded from the steel spring attached tothe membrane, and I heard the sentence, "Yes, I understand youperfectly. " It is a mistake, however, to suppose that the articulationwas by any means perfect, and expectancy no doubt had a great deal to dowith my recognition of the sentence; still, the articulation was there, and I recognized the fact that the indistinctness was entirely due tothe imperfection of the instrument. I will not trouble you by detailingthe various stages through which the apparatus passed, but shall merelysay that after a time I produced the form of instrument shown in Fig. 9, which served very well as a receiving telephone. In this condition myinvention was, in 1876, exhibited at the Centennial Exhibition inPhiladelphia. The telephone shown in Fig. 8 was used as a transmittinginstrument, and that in Fig. 9 as a receiver, so that vocalcommunication was only established in one direction.... 

[Illustration: Fig. 9]

The articulation produced from the instrument shown in Fig. 9 wasremarkably distinct, but its great defect consisted in the fact that itcould not be used as a transmitting instrument, and thus two telephoneswere required at each station, one for transmitting and one forreceiving spoken messages. 

[Illustration: Fig. 10]

It was determined to vary the construction of the telephone shown inFig. 8, and I sought, by changing the size and tension of the membrane, the diameter and thickness of the steel spring, the size and power ofthe magnet, and the coils of insulated wire around their poles, todiscover empirically the exact effect of each element of thecombination, and thus to deduce a more perfect form of apparatus. It wasfound that a marked increase in the loudness of the sounds resulted fromshortening the length of the coils of wire, and by enlarging the irondiaphragm which was glued to the membrane. In the latter case, also, thedistinctness of the articulation was improved. Finally, the membrane ofgoldbeaters' skin was discarded entirely, and a simple iron plate wasused instead, and at once intelligible articulation was obtained. Thenew form of instrument is that shown in Fig. 10, and, as had been longanticipated, it was proved that the only use of the battery was tomagnetize the iron core, for the effects were equally audible when thebattery was omitted and a rod of magnetized steel substituted for theiron core of the magnet. 

[Illustration: Fig. 11]

It was my original intention, as shown in Fig. 3, and it was alwaysclaimed by me, that the final form of telephone would be operated bypermanent magnets in place of batteries, and numerous experiments hadbeen carried on by Mr. Watson and myself privately for the purpose ofproducing this effect. 

At the time the instruments were first exhibited in public the resultsobtained with permanent magnets were not nearly so striking as when avoltaic battery was employed, wherefore we thought it best to exhibitonly the latter form of instrument. 

The interest excited by the first published accounts of the operation ofthe telephone led many persons to investigate the subject, and I doubtnot that numbers of experimenters have independently discovered thatpermanent magnets might be employed instead of voltaic batteries. Indeed, one gentleman, Professor Dolbear, of Tufts College, not onlyclaims to have discovered the magneto-electric telephone, but, Iunderstand, charges me with having obtained the idea from him throughthe medium of a mutual friend. 

A still more powerful form of apparatus was constructed by using apowerful compound horseshoe magnet in place of the straight rod whichhad been previously used (see Fig. 11). Indeed, the sounds produced bymeans of this instrument were of sufficient loudness to be faintlyaudible to a large audience, and in this condition the instrument wasexhibited in the Essex Institute, in Salem, Massachusetts, on the 12thof February, 1877, on which occasion a short speech shouted into asimilar telephone in Boston sixteen miles away, was heard by theaudience in Salem. The tones of the speaker's voice were distinctlyaudible to an audience of six hundred people, but the articulation wasonly distinct at a distance of about six feet. On the same occasion, also, a report of the lecture was transmitted by word of mouth fromSalem to Boston, and published in the papers the next morning. 

From the form of telephone shown in Fig. 10 to the present form of theinstrument (Fig. 12) is but a step. It is, in fact, the arrangement ofFig. 10 in a portable form, the magnet F. H. Being placed inside thehandle and a more convenient form of mouthpiece provided.... 

It was always my belief that a certain ratio would be found between theseveral parts of a telephone, and that the size of the instrument wasimmaterial; but Professor Peirce was the first to demonstrate theextreme smallness of the magnets which might be employed. And here, inorder to show the parallel lines in which we were working, I may mentionthe fact that two or three days after I had constructed a telephone ofthe portable form (Fig. 12), containing the magnet inside the handle, Dr. Channing was kind enough to send me a pair of telephones of asimilar pattern, which had been invented by experimenters at Providence. The convenient form of the mouthpiece shown in Fig. 12, now adopted byme, was invented solely by my friend, Professor Peirce. I must alsoexpress my obligations to my friend and associate, Mr. Thomas A. Watson, of Salem, Massachusetts, who has for two years past given me hispersonal assistance in carrying on my researches. 

In pursuing my investigations I have ever had one end in view--thepractical improvement of electric telegraphy--but I have come acrossmany facts which, while having no direct bearing upon the subject oftelegraphy, may yet possess an interest for you. 

For instance, I have found that a musical tone proceeds from a piece ofplumbago or retort carbon when an intermittent current of electricity ispassed through it, and I have observed the most curious audible effectsproduced by the passage of reversed intermittent currents through thehuman body. A breaker was placed in circuit with the primary wires of aninduction coil, and the fine wires were connected with two strips ofbrass. One of these strips was held closely against the ear, and a loudsound proceeded from it whenever the other slip was touched with theother hand. The strips of brass were next held one in each hand. Theinduced currents occasioned a muscular tremor in the fingers. Uponplacing my forefinger to my ear a loud crackling noise was audible, seemingly proceeding from the finger itself. A friend who was presentplaced my finger to his ear, but heard nothing. I requested him to holdthe strips himself. He was then distinctly conscious of a noise (which Iwas unable to perceive) proceeding from his finger. In this case aportion of the induced current passed through the head of the observerwhen he placed his ear against his own finger, and it is possible thatthe sound was occasioned by a vibration of the surfaces of the ear andfinger in contact. 

When two persons receive a shock from a Ruhmkorff's coil by claspinghands, each taking hold of one wire of the coil with the free hand, asound proceeds from the clasped hands. The effect is not produced whenthe hands are moist. When either of the two touches the body of theother a loud sound comes from the parts in contact. When the arm of oneis placed against the arm of the other, the noise produced can be heardat a distance of several feet. In all these cases a slight shock isexperienced so long as the contact is preserved. The introduction of apiece of paper between the parts in contact does not materiallyinterfere with the production of the sounds, but the unpleasant effectsof the shock are avoided. 

[Illustration: Fig. 12]

When an intermittent current from a Ruhmkorff's coil is passed throughthe arms a musical note can be perceived when the ear is closely appliedto the arm of the person experimented upon. The sound seems to proceedfrom the muscles of the fore-arm and from the biceps muscle. Mr. ElishaGray has also produced audible effects by the passage of electricitythrough the human body. 

An extremely loud musical note is occasioned by the spark of aRuhmkorff's coil when the primary circuit is made and broken withsufficient rapidity. When two breakers of different pitch are causedsimultaneously to open and close the primary circuit a double toneproceeds from the spark. 

A curious discovery, which may be of interest to you, has been made byProfessor Blake. He constructed a telephone in which a rod of soft iron, about six feet in length, was used instead of a permanent magnet. Afriend sang a continuous musical tone into the mouthpiece of atelephone, like that shown in Fig. 12, which was connected with the softiron instrument alluded to above. It was found that the loudness of thesound produced in this telephone varied with the direction in which theiron rod was held, and that the maximum effect was produced when the rodwas in the position of the dipping needle. This curious discovery ofProfessor Blake has been verified by myself. 

When a telephone is placed in circuit with a telegraph line thetelephone is found seemingly to emit sounds on its own account. The mostextraordinary noises are often produced, the causes of which are atpresent very obscure. One class of sounds is produced by the inductiveinfluence of neighbouring wires and by leakage from them, the signals ofthe Morse alphabet passing over neighbouring wires being audible in thetelephone, and another class can be traced to earth currents upon thewire, a curious modification of this sound revealing the presence ofdefective joints in the wire. 

Professor Blake informs me that he has been able to use the railroadtrack for conversational purposes in place of a telegraph wire, and hefurther states that when only one telephone was connected with the trackthe sounds of Morse operating were distinctly audible in the telephone, although the nearest telegraph wires were at least fifty feet distant. 

Professor Peirce has observed the most singular sounds produced from atelephone in connection with a telegraph wire during the auroraborealis, and I have just heard of a curious phenomenon lately observedby Dr. Channing. In the city of Providence, Rhode Island, there is anover-house wire about one mile in extent with a telephone at either end. On one occasion the sound of music and singing was faintly audible inone of the telephones. It seemed as if some one were practising vocalmusic with a pianoforte accompaniment. The natural supposition was thatexperiments were being made with the telephone at the other end of thecircuit, but upon inquiry this proved not to have been the case. Attention having thus been directed to the phenomenon, a watch was keptupon the instruments, and upon a subsequent occasion the same fact wasobserved at both ends of the line by Dr. Channing and his friends. Itwas proved that the sounds continued for about two hours, and usuallycommenced about the same time. A searching examination of the linedisclosed nothing abnormal in its condition, and I am unable to give youany explanation of this curious phenomenon. Dr. Channing has, however, addressed a letter upon the subject to the editor of one of theProvidence papers, giving the names of such songs as were recognized, and full details of the observations, in the hope that publicity maylead to the discovery of the performer, and thus afford a solution ofthe mystery. 

My friend, Mr. Frederick A. Gower, communicated to me a curiousobservation made by him regarding the slight earth connection requiredto establish a circuit for the telephone, and together we carried on aseries of experiments with rather startling results. We took a couple oftelephones and an insulated wire about 100 yards in length into agarden, and were enabled to carry on conversation with the greatest easewhen we held in our hands what should have been the earth wire, so thatthe connection with the ground was formed at either end through ourbodies, our feet being clothed with cotton socks and leather boots. Theday was fine, and the grass upon which we stood was seemingly perfectlydry. Upon standing upon a gravel walk the vocal sounds, though muchdiminished, were still perfectly intelligible, and the same resultoccurred when standing upon a brick wall one foot in height, but nosound was audible when one of us stood upon a block of freestone. 

One experiment which we made is so very interesting that I must speak ofit in detail. Mr. Gower made earth connection at his end of the line bystanding upon a grass plot, whilst at the other end of the line I stoodupon a wooden board. I requested Mr. Gower to sing a continuous musicalnote, and to my surprise the sound was very distinctly audible from thetelephone in my hand. Upon examining my feet I discovered that a singleblade of grass was bent over the edge of the board, and that my foottouched it. The removal of this blade of grass was followed by thecessation of the sound from the telephone, and I found that the moment Itouched with the toe of my boot a blade of grass or the petal of a daisythe sound was again audible. 

The question will naturally arise, Through what length of wire can thetelephone be used? In reply to this I may say that the maximum amount ofresistance through which the undulatory current will pass, and yetretain sufficient force to produce an audible sound at the distant end, has yet to be determined; no difficulty has, however, been experiencedin laboratory experiments in conversing through a resistance of 60, 000ohms, which has been the maximum at my disposal. On one occasion, nothaving a rheostat [for producing resistance] at hand, I passed thecurrent through the bodies of sixteen persons, who stood hand in hand. The longest length of real telegraph line through which I have attemptedto converse has been about 250 miles. On this occasion no difficulty wasexperienced so long as parallel lines were not in operation. Sunday waschosen as the day on which it was probable other circuits would be atrest. Conversation was carried on between myself, in New York, and Mr. Thomas A. Watson, in Boston, until the opening of business upon theother wires. When this happened the vocal sounds were very muchdiminished, but still audible. It seemed, indeed, like talking through astorm. Conversation, though possible, could be carried on withdifficulty, owing to the distracting nature of the interfering currents. 

I am informed by my friend Mr. Preece that conversation has beensuccessfully carried on through a submarine cable, sixty miles inlength, extending from Dartmouth to the Island of Guernsey, by means ofhand telephones. 

PHOTOGRAPHING THE UNSEEN: THE ROENTGEN RAY

H. J. W. DAM

 [By permission from _McClure's Magazine_, April, 1896, copyright by S. S. McClure, Limited. ]

In all the history of scientific discovery there has never been, perhaps, so general, rapid, and dramatic an effect wrought on thescientific centres of Europe as has followed, in the past four weeks, upon an announcement made to the Würzburg Physico-Medical Society, attheir December [1895] meeting, by Professor William Konrad Röntgen, professor of physics at the Royal University of Würzburg. The first newswhich reached London was by telegraph from Vienna to the effect that aProfessor Röntgen, until then the possessor of only a local fame in thetown mentioned, had discovered a new kind of light, which penetrated andphotographed through everything. This news was received with a mildinterest, some amusement, and much incredulity; and a week passed. Then, by mail and telegraph, came daily clear indications of the stir whichthe discovery was making in all the great line of universities betweenVienna and Berlin. Then Röntgen's own report arrived, so cool, sobusiness-like, and so truly scientific in character, that it left nodoubt either of the truth or of the great importance of the precedingreports. To-day, four weeks after the announcement, Röntgen's name isapparently in every scientific publication issued this week in Europe;and accounts of his experiments, of the experiments of others followinghis method, and of theories as to the strange new force which he hasbeen the first to observe, fill pages of every scientific journal thatcomes to hand. And before the necessary time elapses for this article toattain publication in America, it is in all ways probable that thelaboratories and lecture-rooms of the United States will also be givingfull evidence of this contagious arousal of interest over a discovery sostrange that its importance cannot yet be measured, its utility be evenprophesied, or its ultimate effect upon long established scientificbeliefs be even vaguely foretold. 

The Röntgen rays are certain invisible rays resembling, in manyrespects, rays of light, which are set free when a high-pressureelectric current is discharged through a vacuum tube. A vacuum tube is aglass tube from which all the air, down to one-millionth of anatmosphere, has been exhausted after the insertion of a platinum wire ineither end of the tube for connection with the two poles of a battery orinduction coil. When the discharge is sent through the tube, thereproceeds from the anode--that is, the wire which is connected with thepositive pole of the battery--certain bands of light, varying in colourwith the colour of the glass. But these are insignificant in comparisonwith the brilliant glow which shoots from the cathode, or negative wire. This glow excites brilliant phosphorescence in glass and manysubstances, and these "cathode rays, " as they are called, were observedand studied by Hertz; and more deeply by his assistant, ProfessorLenard, Lenard having, in 1894, reported that the cathode rays wouldpenetrate thin films of aluminum, wood, and other substances, andproduce photographic results beyond. It was left, however, for ProfessorRöntgen to discover that during the discharge quite other rays are setfree, which differ greatly from those described by Lenard as cathoderays. The most marked difference between the two is the fact thatRöntgen rays are not deflected by a magnet, indicating a very essentialdifference, while their range and penetrative power are incomparablygreater. In fact, all those qualities which have lent a sensationalcharacter to the discovery of Röntgen's rays were mainly absent fromthose of Lenard, to the end that, although Röntgen has not been workingin an entirely new field, he has by common accord been freely grantedall the honors of a great discovery. 

Exactly what kind of a force Professor Röntgen has discovered he doesnot know. As will be seen below, he declines to call it a new kind oflight, or a new form of electricity. He has given it the name of the Xrays. Others speak of it as the Röntgen rays. Thus far its results only, and not its essence, are known. In the terminology of science it isgenerally called "a new mode of motion, " or, in other words, a newforce. As to whether it is or not actually a force new to science, orone of the known forces masquerading under strange conditions, weightyauthorities are already arguing. More than one eminent scientist hasalready affected to see in it a key to the great mystery of the law ofgravity. All who have expressed themselves in print have admitted, withmore or less frankness, that, in view of Röntgen's discovery, sciencemust forthwith revise, possibly to a revolutionary degree, the longaccepted theories concerning the phenomena of light and sound. That theX rays, in their mode of action, combine a strange resemblance to bothsound and light vibrations, and are destined to materially affect, ifthey do not greatly alter, our views of both phenomena, is alreadycertain; and beyond this is the opening into a new and unknown field ofphysical knowledge, concerning which speculation is already eager, andexperimental investigation already in hand, in London, Paris, Berlin, and, perhaps, to a greater or less extent, in every well-equippedphysical laboratory in Europe. 

This is the present scientific aspect of the discovery. But, unlike mostepoch-making results from laboratories, this discovery is one which, toa very unusual degree, is within the grasp of the popular andnon-technical imagination. Among the other kinds of matter which theserays penetrate with ease is human flesh. That a new photography hassuddenly arisen which can photograph the bones, and, before long, theorgans of the human body; that a light has been found which canpenetrate, so as to make a photographic record, through everything froma purse or a pocket to the walls of a room or a house, is news whichcannot fail to startle everybody. That the eye of the physician orsurgeon, long baffled by the skin, and vainly seeking to penetrate theunfortunate darkness of the human body, is now to be supplemented by acamera, making all the parts of the human body as visible, in a way, asthe exterior, appears certainly to be a greater blessing to humanitythan even the Listerian antiseptic system of surgery; and its benefitsmust inevitably be greater than those conferred by Lister, great as thelatter have been. Already, in the few weeks since Röntgen'sannouncement, the results of surgical operations under the new systemare growing voluminous. In Berlin, not only new bone fractures are beingimmediately photographed, but joined fractures, as well, in order toexamine the results of recent surgical work. In Vienna, imbedded bulletsare being photographed, instead of being probed for, and extracted withcomparative ease. In London, a wounded sailor, completely paralyzed, whose injury was a mystery, has been saved by the photographing of anobject imbedded in the spine, which, upon extraction, proved to be asmall knife-blade. Operations for malformations, hitherto obscure, butnow clearly revealed by the new photography, are already becomingcommon, and are being reported from all directions. Professor Czermarkof Graz has photographed the living skull, denuded of flesh and hair, and has begun the adaptation of the new photography to brain study. Therelation of the new rays to thought rays is being eagerly discussed inwhat may be called the non-exact circles and journals; and all thatnumerous group of inquirers into the occult, the believers inclairvoyance, spiritualism, telepathy, and kindred orders of allegedphenomena, are confident of finding in the new force long-sought factsin proof of their claims. Professor Neusser in Vienna has photographedgallstones in the liver of one patient (the stone showing snow-white inthe negative), and a stone in the bladder of another patient. Hisresults so far induce him to announce that all the organs of the humanbody can, and will, shortly, be photographed. Lannelongue of Paris hasexhibited to the Academy of Science photographs of bones showinginherited tuberculosis which had not otherwise revealed itself. Berlinhas already formed a society of forty for the immediate prosecution ofresearches into both the character of the new force and itsphysiological possibilities. In the next few weeks these strangeannouncements will be trebled or quadrupled, giving the best evidencefrom all quarters of the great future that awaits the Röntgen rays, andthe startling impetus to the universal search for knowledge that hascome at the close of the nineteenth century from the modest littlelaboratory in the Pleicher Ring at Würzburg. 

The Physical Institute, Professor Röntgen's particular domain, is amodest building of two stories and basement, the upper storyconstituting his private residence, and the remainder of the buildingbeing given over to lecture rooms, laboratories, and their attendantoffices. At the door I was met by an old serving-man of the idolatrousorder, whose pain was apparent when I asked for "Professor" Röntgen, andhe gently corrected me with "Herr Doctor Röntgen. " As it was evident, however, that we referred to the same person, he conducted me along awide, bare hall, running the length of the building, with blackboardsand charts on the walls. At the end he showed me into a small room onthe right. This contained a large table desk, and a small table by thewindow, covered by photographs, while the walls held rows of shelvesladen with laboratory and other records. An open door led into asomewhat larger room, perhaps twenty feet by fifteen, and I found myselfgazing into a laboratory which was the scene of the discovery--alaboratory which, though in all ways modest, is destined to beenduringly historical. 

There was a wide table shelf running along the farther side, in front ofthe two windows, which were high, and gave plenty of light. In thecentre was a stove; on the left, a small cabinet whose shelves held thesmall objects which the professor had been using. There was a table inthe left-hand corner; and another small table--the one on which livingbones were first photographed--was near the stove, and a Ruhmkorff coilwas on the right. The lesson of the laboratory was eloquent. Compared, for instance, with the elaborate, expensive, and complete apparatus of, say, the University of London, or of any of the great Americanuniversities, it was bare and unassuming to a degree. It mutely saidthat in the great march of science it is the genius of man, and not theperfection of appliances, that breaks new ground in the great territoryof the unknown. It also caused one to wonder at and endeavour to imaginethe great things which are to be done through elaborate appliances withthe Röntgen rays--a field in which the United States, with its foremostgenius in invention, will very possibly, if not probably, take thelead--when the discoverer himself had done so much with so little. Already, in a few weeks, a skilled London operator, Mr. A. A. C. Swinton, has reduced the necessary time of exposure for Röntgenphotographs from fifteen minutes to four. He used, however, a Tesla oilcoil, discharged by twelve half-gallon Leyden jars, with an alternatingcurrent of twenty thousand volts' pressure. Here were no oil coils, Leyden jars, or specially elaborate and expensive machines. There wereonly a Ruhmkorff coil and Crookes (vacuum) tube and the man himself. 

Professor Röntgen entered hurriedly, something like an amiable gust ofwind. He is a tall, slender, and loose-limbed man, whose wholeappearance bespeaks enthusiasm and energy. He wore a dark blue sacksuit, and his long, dark hair stood straight up from his forehead, as ifhe were permanently electrified by his own enthusiasm. His voice is fulland deep, he speaks rapidly, and, altogether, he seems clearly a manwho, once upon the track of a mystery which appealed to him, wouldpursue it with unremitting vigor. His eyes are kind, quick, andpenetrating; and there is no doubt that he much prefers gazing at aCrookes tube to beholding a visitor, visitors at present robbing him ofmuch valued time. The meeting was by appointment, however, and hisgreeting was cordial and hearty. In addition to his own language hespeaks French well and English scientifically, which is different fromspeaking it popularly. These three tongues being more or less within theequipment of his visitor, the conversation proceeded on an internationalor polyglot basis, so to speak, varying at necessity's demand. 

It transpired in the course of inquiry, that the professor is a marriedman and fifty years of age, though his eyes have the enthusiasm oftwenty-five. He was born near Zurich, and educated there, and completedhis studies and took his degree at Utrecht. He has been at Würzburgabout seven years, and had made no discoveries which he considered ofgreat importance prior to the one under consideration. These detailswere given under good-natured protest, he failing to understand why hispersonality should interest the public. He declined to admire himself orhis results in any degree, and laughed at the idea of being famous. Theprofessor is too deeply interested in science to waste any time inthinking about himself. His emperor had feasted, flattered, anddecorated him, and he was loyally grateful. It was evident, however, that fame and applause had small attractions for him, compared to themysteries still hidden in the vacuum tubes of the other room. 

"Now, then, " said he, smiling, and with some impatience, when thepreliminary questions at which he chafed were over, "you have come tosee the invisible rays. "

"Is the invisible visible?"

"Not to the eye; but its results are. Come in here. "

[Illustration: BONES OF A HUMAN FOOT PHOTOGRAPHED THROUGH THE FLESH

From a photograph by A. A. C. Swinton, Victoria Street, London. Exposure, fifty-five seconds]

He led the way to the other square room mentioned, and indicated theinduction coil with which his researches were made, an ordinaryRuhmkorff coil, with a spark of from four to six inches, charged by acurrent of twenty amperes. Two wires led from the coil, through an opendoor, into a smaller room on the right. In this room was a small tablecarrying a Crookes tube connected with the coil. The most strikingobject in the room, however, was a huge and mysterious tin box aboutseven feet high and four feet square. It stood on end, like a hugepacking case, its side being perhaps five inches from the Crookes tube. 

The professor explained the mystery of the tin box, to the effect thatit was a device of his own for obtaining a portable dark-room. When hebegan his investigations he used the whole room, as was shown by theheavy blinds and curtains so arranged as to exclude the entrance of allinterfering light from the windows. In the side of the tin box, at thepoint immediately against the tube, was a circular sheet of aluminum onemillimetre in thickness, and perhaps eighteen inches in diameter, soldered to the surrounding tin. To study his rays the professor hadonly to turn on the current, enter the box, close the door, and inperfect darkness inspect only such light or light effects as he had aright to consider his own, hiding his light, in fact, not under theBiblical bushel, but in a more commodious box. 

"Step inside, " said he, opening the door, which was on the side of thebox farthest from the tube. I immediately did so, not altogether certainwhether my skeleton was to be photographed for general inspection, or mysecret thoughts held up to light on a glass plate. "You will find asheet of barium paper on the shelf, " he added, and then went away to thecoil. The door was closed, and the interior of the box became blackdarkness. The first thing I found was a wooden stool, on which Iresolved to sit. Then I found the shelf on the side next the tube, andthen the sheet of paper prepared with barium platinocyanide. I was thusbeing shown the first phenomenon which attracted the discoverer'sattention and led to his discovery, namely, the passage of rays, themselves wholly invisible, whose presence was only indicated by theeffect they produced on a piece of sensitized photographic paper. 

A moment later, the black darkness was penetrated by the rapid snappingsound of the high-pressure current in action, and I knew that the tubeoutside was glowing. I held the sheet vertically on the shelf, perhapsfour inches from the plate. There was no change, however, and nothingwas visible. 

"Do you see anything?" he called. 

"No. "

"The tension is not high enough;" and he proceeded to increase thepressure by operating an apparatus of mercury in long vertical tubesacted upon automatically by a weight lever which stood near the coil. Ina few moments the sound of the discharge again began, and then I made myfirst acquaintance with the Röntgen rays. 

The moment the current passed, the paper began to glow. A yellowishgreen light spread all over its surface in clouds, waves and flashes. The yellow-green luminescence, all the stranger and stronger in thedarkness, trembled, wavered, and floated over the paper, in rhythm withthe snapping of the discharge. Through the metal plate, the paper, myself, and the tin box, the invisible rays were flying, with an effectstrange, interesting and uncanny. The metal plate seemed to offer noappreciable resistance to the flying force, and the light was as richand full as if nothing lay between the paper and the tube. 

"Put the book up, " said the professor. 

I felt upon the shelf, in the darkness, a heavy book, two inches inthickness, and placed this against the plate. It made no difference. Therays flew through the metal and the book as if neither had been there, and the waves of light, rolling cloud-like over the paper, showed nochange in brightness. It was a clear, material illustration of the easewith which paper and wood are penetrated. And then I laid book and paperdown, and put my eyes against the rays. All was blackness, and I neithersaw nor felt anything. The discharge was in full force, and the rayswere flying through my head, and, for all I knew, through the side ofthe box behind me. But they were invisible and impalpable. They gave nosensation whatever. Whatever the mysterious rays may be, they are not tobe seen, and are to be judged only by their works. 

I was loath to leave this historical tin box, but time pressed. Ithanked the professor, who was happy in the reality of his discovery andthe music of his sparks. Then I said: "Where did you first photographliving bones?"

"Here, " he said, leading the way into the room where the coil stood. Hepointed to a table on which was another--the latter a smallshort-legged wooden one with more the shape and size of a wooden seat. It was two feet square and painted coal black. I viewed it withinterest. I would have bought it, for the little table on which lightwas first sent through the human body will some day be a greathistorical curiosity; but it was not for sale. A photograph of it wouldhave been a consolation, but for several reasons one was not to be hadat present. However, the historical table was there, and was dulyinspected. 

"How did you take the first hand photograph?" I asked. 

The professor went over to a shelf by the window, where lay a number ofprepared glass plates, closely wrapped in black paper. He put a Crookestube underneath the table, a few inches from the under side of its top. Then he laid his hand flat on the top of the table, and placed the glassplate loosely on his hand. 

"You ought to have your portrait painted in that attitude, " I suggested. 

"No, that is nonsense, " said he, smiling. 

"Or be photographed. " This suggestion was made with a deeply hiddenpurpose. 

The rays from the Röntgen eyes instantly penetrated the deeply hiddenpurpose. "Oh, no, " said he; "I can't let you make pictures of me. I amtoo busy. " Clearly the professor was entirely too modest to gratify thewishes of the curious world. 

"Now, Professor, " said I, "will you tell me the history of thediscovery?"

"There is no history, " he said. "I have been for a long time interestedin the problem of the cathode rays from a vacuum tube as studied byHertz and Lenard. I had followed their and other researches with greatinterest, and determined, as soon as I had the time, to make someresearches of my own. This time I found at the close of last October. Ihad been at work for some days when I discovered something new. "

"What was the date?"

"The eighth of November. "

"And what was the discovery?"

"I was working with a Crookes tube covered by a shield of blackcardboard. A piece of barium platinocyanide paper lay on the benchthere. I had been passing a current through the tube, and I noticed apeculiar black line across the paper. "

"What of that?"

"The effect was one which could only be produced, in ordinary parlance, by the passage of light. No light could come from the tube, because theshield which covered it was impervious to any light known, even that ofthe electric arc. "

"And what did you think?"

"I did not think; I investigated. I assumed that the effect must havecome from the tube, since its character indicated that it could comefrom nowhere else. I tested it. In a few minutes there was no doubtabout it. Rays were coming from the tube which had a luminescent effectupon the paper. I tried it successfully at greater and greaterdistances, even at two metres. It seemed at first a new kind ofinvisible light. It was clearly something new, something unrecorded. "

"Is it light?"

"No. "

"Is it electricity?"

"Not in any known form. "

"What is it?"

"I don't know. "

And the discoverer of the X rays thus stated as calmly his ignorance oftheir essence as has everybody else who has written on the phenomenathus far. 

"Having discovered the existence of a new kind of rays, I of coursebegan to investigate what they would do. " He took up a series ofcabinet-sized photographs. "It soon appeared from tests that the rayshad penetrative powers to a degree hitherto unknown. They penetratedpaper, wood, and cloth with ease; and the thickness of the substancemade no perceptible difference, within reasonable limits. " He showedphotographs of a box of laboratory weights of platinum, aluminum, andbrass, they and the brass hinges all having been photographed from aclosed box, without any indication of the box. Also a photograph of acoil of fine wire, wound on a wooden spool, the wire having beenphotographed, and the wood omitted. "The rays, " he continued, "passedthrough all the metals tested, with a facility varying, roughlyspeaking, with the density of the metal. These phenomena I havediscussed carefully in my report to the Würzburg society, and you willfind all the technical results therein stated. " He showed a photographof a small sheet of zinc. This was composed of smaller plates solderedlaterally with solders of different metallic proportions. The differinglines of shadow, caused by the difference in the solders, were visibleevidence that a new means of detecting flaws and chemical variations inmetals had been found. A photograph of a compass showed the needle anddial taken through the closed brass cover. The markings of the dial werein red metallic paint, and thus interfered with the rays, and werereproduced. "Since the rays had this great penetrative power, it seemednatural that they should penetrate flesh, and so it proved inphotographing the hand, as I showed you. "

A detailed discussion of the characteristics of his rays the professorconsidered unprofitable and unnecessary. He believes, though, that thesemysterious radiations are not light, because their behaviour isessentially different from that of light rays, even those light rayswhich are themselves invisible. The Röntgen rays cannot be reflected byreflecting surfaces, concentrated by lenses, or refracted or diffracted. They produce photographic action on a sensitive film, but their actionis weak as yet, and herein lies the first important field of theirdevelopment. The professor's exposures were comparatively long--anaverage of fifteen minutes in easily penetrable media, and half an houror more in photographing the bones of the hand. Concerning vacuum tubes, he said that he preferred the Hittorf, because it had the most perfectvacuum, the highest degree of air exhaustion being the consummation mostdesirable. In answer to a question, "What of the future?" he said:

"I am not a prophet, and I am opposed to prophesying. I am pursuing myinvestigations, and as fast as my results are verified I shall make thempublic. "

"Do you think the rays can be so modified as to photograph the organs ofthe human body?"

In answer he took up the photograph of the box of weights. "Here arealready modifications, " he said, indicating the various degrees ofshadow produced by the aluminum, platinum, and brass weights, the brasshinges, and even the metallic stamped lettering on the cover of the box, which was faintly perceptible. 

"But Professor Neusser has already announced that the photographing ofthe various organs is possible. "

"We shall see what we shall see, " he said. "We have the start now; thedevelopment will follow in time. "

"You know the apparatus for introducing the electric light into thestomach?"

"Yes. "

"Do you think that this electric light will become a vacuum tube forphotographing, from the stomach, any part of the abdomen or thorax?"

The idea of swallowing a Crookes tube, and sending a high frequencycurrent down into one's stomach, seemed to him exceedingly funny. "WhenI have done it, I will tell you, " he said, smiling, resolute in abidingby results. 

"There is much to do, and I am busy, very busy, " he said in conclusion. He extended his hand in farewell, his eyes already wandering toward hiswork in the inside room. And his visitor promptly left him; the words, "I am busy, " said in all sincerity, seeming to describe in a singlephrase the essence of his character and the watchword of a very unusualman. 

Returning by way of Berlin, I called upon Herr Spies of the Urania, whose photographs after the Röntgen method were the first made public, and have been the best seen thus far. In speaking of the discovery hesaid:

"I applied it, as soon as the penetration of flesh was apparent, to thephotograph of a man's hand. Something in it had pained him for years, and the photograph at once exhibited a small foreign object, as you cansee;" and he exhibited a copy of the photograph in question. "The speckthere is a small piece of glass, which was immediately extracted, andwhich, in all probability, would have otherwise remained in the man'shand to the end of his days. " All of which indicates that the needlewhich has pursued its travels in so many persons, through so many years, will be suppressed by the camera. 

"My next object is to photograph the bones of the entire leg, " continuedHerr Spies. "I anticipate no difficulty, though it requires some thoughtin manipulation. "

It will be seen that the Röntgen rays and their marvellous practicalpossibilities are still in their infancy. The first successfulmodification of the action of the rays so that the varying densities ofbodily organs will enable them to be photographed will bring all suchmorbid growths as tumours and cancers into the photographic field, tosay nothing of vital organs which may be abnormally developed ordegenerate. How much this means to medical and surgical practice itrequires little imagination to conceive. Diagnosis, long a painfullyuncertain science, has received an unexpected and wonderful assistant;and how greatly the world will benefit thereby, how much pain will besaved, only the future can determine. In science a new door has beenopened where none was known to exist, and a side-light on phenomena hasappeared, of which the results may prove as penetrating and astonishingas the Röntgen rays themselves. The most agreeable feature of thediscovery is the opportunity it gives for other hands to help; and thework of these hands will add many new words to the dictionaries, manynew facts to science, and, in the years long ahead of us, fill many morevolumes than there are paragraphs in this brief and imperfect account. 

THE WIRELESS TELEGRAPH

GEORGE ILES

 [From "Flame, Electricity and the Camera, " copyright by Doubleday, Page & Co. , New York. ]

In a series of experiments interesting enough but barren of utility, thewater of a canal, river, or bay has often served as a conductor for thetelegraph. Among the electricians who have thus impressed water intotheir service was Professor Morse. In 1842 he sent a few signals acrossthe channel from Castle Garden, New York, to Governor's Island, adistance of a mile. With much better results, he sent messages, later inthe same year, from one side of the canal at Washington to the other, adistance of eighty feet, employing large copper plates at each terminal. The enormous current required to overcome the resistance of water hasbarred this method from practical adoption. 

We pass, therefore, to electrical communication as effected byinduction--the influence which one conductor exerts on another throughan intervening insulator. At the outset we shall do well to bear in mindthat magnetic phenomena, which are so closely akin to electrical, arealways inductive. To observe a common example of magnetic induction, wehave only to move a horseshoe magnet in the vicinity of a compassneedle, which will instantly sway about as if blown hither and thitherby a sharp draught of air. This action takes place if a slate, a pane ofglass, or a shingle is interposed between the needle and its perturber. There is no known insulator for magnetism, and an induction of this kindexerts itself perceptibly for many yards when large masses of iron arepolarised, so that the derangement of compasses at sea from moving ironobjects aboard ship, or from ferric ores underlying a sea-coast, is aconstant peril to the mariner. 

Electrical conductors behave much like magnetic masses. A currentconveyed by a conductor induces a counter-current in all surroundingbodies, and in a degree proportioned to their conductive power. Thiseffect is, of course, greatest upon the bodies nearest at hand, and wehave already remarked its serious retarding effect in ocean telegraphy. When the original current is of high intensity, it can induce aperceptible current in another wire at a distance of several miles. In1842 Henry remarked that electric waves had this quality, but in thatearly day of electrical interpretation the full significance of the facteluded him. In the top room of his house he produced a spark an inchlong, which induced currents in wires stretched in his cellar, throughtwo thick floors and two rooms which came between. Induction of thissort causes the annoyance, familiar in single telephonic circuits, ofbeing obliged to overhear other subscribers, whose wires are often faraway from our own. 

The first practical use of induced currents in telegraphy was when Mr. Edison, in 1885, enabled the trains on a line of the Staten IslandRailroad to be kept in constant communication with a telegraphic wire, suspended in the ordinary way beside the track. The roof of a car was ofinsulated metal, and every tap of an operator's key within the wallselectrified the roof just long enough to induce a brief pulse throughthe telegraphic circuit. In sending a message to the car this wire was, moment by moment, electrified, inducing a response first in the carroof, and next in the "sounder" beneath it. This remarkable apparatus, afterward used on the Lehigh Valley Railroad, was discontinued from lackof commercial support, although it would seem to be advantageous tomaintain such a service on other than commercial grounds. In case ofchance obstructions on the track, or other peril, to be able tocommunicate at any moment with a train as it speeds along might meansafety instead of disaster. The chief item in the cost of this system isthe large outlay for a special telegraphic wire. 

The next electrician to employ induced currents in telegraphy was Mr. (now Sir) William H. Preece, the engineer then at the head of theBritish telegraph system. Let one example of his work be cited. In 1896a cable was laid between Lavernock, near Cardiff, on the BristolChannel, and Flat Holme, an island three and a third miles off. As thechannel at this point is a much-frequented route and anchor ground, thecable was broken again and again. As a substitute for it Mr. Preece, in1898, strung wires along the opposite shores, and found that an electricpulse sent through one wire instantly made itself heard in a telephoneconnected with the other. It would seem that in this etheric form oftelegraphy the two opposite lines of wire must be each as long as thedistance which separates them; therefore, to communicate across theEnglish Channel from Dover to Calais would require a line along eachcoast at least twenty miles in length. Where such lines exist forordinary telegraphy, they might easily lend themselves to the Preecesystem of signalling in case a submarine cable were to part. 

Marconi, adopting electrostatic instead of electro-magnetic waves, haswon striking results. Let us note the chief of his forerunners, as theyprepared the way for him. In 1864 Maxwell observed that electricity andlight have the same velocity, 186, 400 miles a second, and he formulatedthe theory that electricity propagates itself in waves which differ fromthose of light only in being longer. This was proved to be true byHertz, who in 1888 showed that where alternating currents of very highfrequency were set up in an open circuit, the energy might be conveyedentirely away from the circuit into the surrounding space as electricwaves. His detector was a nearly closed circle of wire, the ends beingsoldered to metal balls almost in contact. With this simple apparatus hedemonstrated that electric waves move with the speed of light, and thatthey can be reflected and refracted precisely as if they formed avisible beam. At a certain intensity of strain the air insulation brokedown, and the air became a conductor. This phenomenon of passing quitesuddenly from a non-conductive to a conductive state is, as we shallduly see, also to be noted when air or other gases are exposed to the Xray. 

Now for the effect of electric waves such as Hertz produced, when theyimpinge upon substances reduced to powder or filings. Conductors, suchas the metals, are of inestimable service to the electrician; of equalvalue are non-conductors, such as glass and gutta-percha, as theystrictly fence in an electric stream. A third and remarkable vista opensto experiment when it deals with substances which, in their normalstate, are non-conductive, but which, agitated by an electric wave, instantly become conductive in a high degree. As long ago as 1866 Mr. S. A. Varley noticed that black lead, reduced to a loose dust, effectuallyintercepted a current from fifty Daniell cells, although the batterypoles were very near each other. When he increased the electric tensionfour- to six-fold, the black-lead particles at once compacted themselvesso as to form a bridge of excellent conductivity. On this principle heinvented a lightning-protector for electrical instruments, the incomingflash causing a tiny heap of carbon dust to provide it with a paththrough which it could safely pass to the earth. Professor TemistocleCalzecchi Onesti of Fermo, in 1885, in an independent series ofresearches, discovered that a mass of powdered copper is a non-conductoruntil an electric wave beats upon it; then, in an instant, the massresolves itself into a conductor almost as efficient as if it were astout, unbroken wire. Professor Edouard Branly of Paris, in 1891, onthis principle devised a coherer, which passed from resistance toinvitation when subjected to an electric impulse from afar. He enhancedthe value of his device by the vital discovery that the conductivitybestowed upon filings by electric discharges could be destroyed bysimply shaking or tapping them apart. 

In a homely way the principle of the coherer is often illustrated inordinary telegraphic practice. An operator notices that his instrumentis not working well, and he suspects that at some point in his circuitthere is a defective contact. A little dirt, or oxide, or dampness, hascome in between two metallic surfaces; to be sure, they still touch eachother, but not in the firm and perfect way demanded for his work. Accordingly he sends a powerful current abruptly into the line, whichclears its path thoroughly, brushes aside dirt, oxide, or moisture, andthe circuit once more is as it should be. In all likelihood, the cohereris acted upon in the same way. Among the physicists who studied it inits original form was Dr. Oliver J. Lodge. He improved it so much that, in 1894, at the Royal Institution in London, he was able to show it asan electric eye that registered the impact of invisible rays at adistance of more than forty yards. He made bold to say that thisdistance might be raised to half a mile. 

As early as 1879 Professor D. E. Hughes began a series of experiments inwireless telegraphy, on much the lines which in other hands have nowreached commercial as well as scientific success. Professor Hughes wasthe inventor of the microphone, and that instrument, he declared, affords an unrivalled means of receiving wireless messages, since itrequires no tapping to restore its non-conductivity. In his researchesthis investigator was convinced that his signals were propagated, not byelectro-magnetic induction, but by aerial electric waves spreading outfrom an electric spark. Early in 1880 he showed his apparatus toProfessor Stokes, who observed its operation carefully. His dictum wasthat he saw nothing which could not be explained by knownelectro-magnetic effects. This erroneous judgment so discouragedProfessor Hughes that he desisted from following up his experiments, andthus, in all probability, the birth of the wireless telegraph was forseveral years delayed. [3]

[Illustration: Fig. 71. --Marconi coherer, enlarged view]

The coherer, as improved by Marconi, is a glass tube about one andone-half inches long and about one-twelfth of an inch in internaldiameter. The electrodes are inserted in this tube so as almost totouch; between them is about one-thirtieth of an inch filled with apinch of the responsive mixture which forms the pivot of the wholecontrivance. This mixture is 90 per cent. Nickel filings, 10 per cent. Hard silver filings, and a mere trace of mercury; the tube is exhaustedof air to within one ten-thousandth part (Fig. 71). How does this trifleof metallic dust manage loudly to utter its signals through atelegraphic sounder, or forcibly indent them upon a moving strip ofpaper? Not directly, but indirectly, as the very last refinement ofinitiation. Let us imagine an ordinary telegraphic battery strong enoughloudly to tick out a message. Be it ever so strong it remains silentuntil its circuit is completed, and for that completion the merest touchsuffices. Now the thread of dust in the coherer forms part of such atelegraphic circuit: as loose dust it is an effectual bar and obstacle, under the influence of electric waves from afar it changes instantly toa coherent metallic link which at once completes the circuit anddelivers the message. 

An electric impulse, almost too attenuated for computation, is here ableto effect such a change in a pinch of dust that it becomes a free avenueinstead of a barricade. Through that avenue a powerful blow from a localstore of energy makes itself heard and felt. No device of the triggerclass is comparable with this in delicacy. An instant after a signal hastaken its way through the coherer a small hammer strikes the tiny tube, jarring its particles asunder, so that they resume their normal state ofhigh resistance. We may well be astonished at the sensitiveness of themetallic filings to an electric wave originating many miles away, butlet us remember how clearly the eye can see a bright lamp at the samedistance as it sheds a sister beam. Thus far no substance has beendiscovered with a mechanical responsiveness to so feeble a ray of light;in the world of nature and art the coherer stands alone. The electricwaves employed by Marconi are about four feet long, or have a frequencyof about 250, 000, 000 per second. Such undulations pass readily throughbrick or stone walls, through common roofs and floors--indeed, throughall substances which are non-conductive to electric waves of ordinarylength. Were the energy of a Marconi sending-instrument applied to anarc-lamp, it would generate a beam of a thousand candle-power. We havethus a means of comparing the sensitiveness of the retina to light withthe responsiveness of the Marconi coherer to electric waves, after bothradiations have undergone a journey of miles. 

An essential feature of this method of etheric telegraphy, due toMarconi himself, is the suspension of a perpendicular wire at eachterminus, its length twenty feet for stations a mile apart, forty feetfor four miles, and so on, the telegraphic distance increasing as thesquare of the length of suspended wire. In the Kingstown regatta, July, 1898, Marconi sent from a yacht under full steam a report to the shorewithout the loss of a moment from start to finish. This feat wasrepeated during the protracted contest between the _Columbia_ and the_Shamrock_ yachts in New York Bay, October, 1899. On March 28, 1899, Marconi signals put Wimereux, two miles north of Boulogne, incommunication with the South Foreland Lighthouse, thirty-two milesoff. [4] In August, 1899, during the manoeuvres of the British navy, similar messages were sent as far as eighty miles. It was clearlydemonstrated that a new power had been placed in the hands of a navalcommander. "A touch on a button in a flagship is all that is now neededto initiate every tactical evolution in a fleet, and insure an almostautomatic precision in the resulting movements of the ships. Theflashing lantern is superseded at night, flags and the semaphore by day, or, if these are retained, it is for services purely auxiliary. Thehideous and bewildering shrieks of the steam-siren need no longer beheard in a fog, and the uncertain system of gun signals will soon becomea thing of the past. " The interest of the naval and military strategistin the Marconi apparatus extends far beyond its communication ofintelligence. Any electrical appliance whatever may be set in motion bythe same wave that actuates a telegraphic sounder. A fuse may beignited, or a motor started and directed, by apparatus connected withthe coherer, for all its minuteness. Mr. Walter Jamieson and Mr. JohnTrotter have devised means for the direction of torpedoes by etherwaves, such as those set at work in the wireless telegraph. Two rodsprojecting above the surface of the water receive the waves, and are incircuit with a coherer and a relay. At the will of the distant operatora hollow wire coil bearing a current draws in an iron core either to theright or to the left, moving the helm accordingly. 

As the news of the success of the Marconi telegraph made its way to theLondon Stock Exchange there was a fall in the shares of cable companies. The fear of rivalry from the new invention was baseless. As but fifteenwords a minute are transmissible by the Marconi system, it evidentlydoes not compete with a cable, such as that between France and England, which can transmit 2, 500 words a minute without difficulty. The Marconitelegraph comes less as a competitor to old systems than as a mode ofcommunication which creates a field of its own. We have seen what it mayaccomplish in war, far outdoing any feat possible to other apparatus, acoustic, luminous, or electrical. In quite as striking fashion does itbreak new ground in the service of commerce and trade. It enableslighthouses continually to spell their names, so that receivers aboardship may give the steersmen their bearings even in storm and fog. In thecrowded condition of the steamship "lanes" which cross the Atlantic, apriceless security against collision is afforded the man at the helm. On November 15, 1899, Marconi telegraphed from the American liner _St. Paul_ to the Needles, sixty-six nautical miles away. On December 11 and12, 1901, he received wireless signals near St. John's, Newfoundland, sent from Poldhu, Cornwall, England, or a distance of 1, 800 miles, --afeat which astonished the world. In many cases the telegraphic businessto an island is too small to warrant the laying of a cable; hence wefind that Trinidad and Tobago are to be joined by the wireless system, as also five islands of the Hawaiian group, eight to sixty-one milesapart. 

A weak point in the first Marconi apparatus was that anybody within theworking radius of the sending-instrument could read its messages. Tomodify this objection secret codes were at times employed, as incommerce and diplomacy. A complete deliverance from this difficulty ispromised in attuning a transmitter and a receiver to the same note, sothat one receiver, and no other, shall respond to a particular frequencyof impulses. The experiments which indicate success in this vitalparticular have been conducted by Professor Lodge. 

When electricians, twenty years ago, committed energy to a wire and thusenabled it to go round a corner, they felt that they had done well. TheHertz waves sent abroad by Marconi ask no wire, as they find their way, not round a corner, but through a corner. On May 1, 1899, a party ofFrench officers on board the _Ibis_ at Sangatte, near Calais, spoke toWimereux by means of a Marconi apparatus, with Cape Grisnez, a loftypromontory, intervening. In ascertaining how much the earth and the seamay obstruct the waves of Hertz there is a broad and fruitful field forinvestigation. "It may be, " says Professor John Trowbridge, "that suchlong electrical waves roll around the surface of such obstructions verymuch as waves of sound and of water would do. "

[Illustration: Fig. 73--Discontinuous electric waves]

[Illustration: Fig. 74--Wehnelt interrupter]

It is singular how discoveries sometimes arrive abreast of each other soas to render mutual aid, or supply a pressing want almost as soon as itis felt. The coherer in its present form is actuated by waves ofcomparatively low frequency, which rise from zero to full height inextremely brief periods, and are separated by periods decidedly longer(Fig. 73). What is needed is a plan by which the waves may flow eithercontinuously or so near together that they may lend themselves toattuning. Dr. Wehnelt, by an extraordinary discovery, may, in alllikelihood, provide the lacking device in the form of his interrupter, which breaks an electric circuit as often as two thousand times asecond. The means for this amazing performance are simplicity itself(Fig. 74). A jar, _a_, containing a solution of sulphuric acid has twoelectrodes immersed in it; one of them is a lead plate of large surface, _b_; the other is a small platinum wire which protrudes from a glasstube, _d_. A current passing through the cell between the two metals at_c_ is interrupted, in ordinary cases five hundred times a second, andin extreme cases four times as often, by bubbles of gas given off fromthe wire instant by instant. 

FOOTNOTES:

[3] "History of the Wireless Telegraph, " by J. J. Fahie. Edinburgh andLondon, William Blackwood & Sons; New York, Dodd, Mead & Co. , 1899. Thiswork is full of interesting detail, well illustrated. 

[4] The value of wireless telegraphy in relation to disasters at sea wasproved in a remarkable way yesterday morning. While the Channel wasenveloped in a dense fog, which had lasted throughout the greater partof the night, the East Goodwin Lightship had a very narrow escape fromsinking at her moorings by being run into by the steamship _R. F. Matthews_, 1, 964 tons gross burden, of London, outward bound from theThames. The East Goodwin Lightship is one of four such vessels markingthe Goodwin Sands, and, curiously enough, it happens to be the one shipwhich has been fitted out with Signor Marconi's installation forwireless telegraphy. The vessel was moored about twelve miles to thenortheast of the South Foreland Lighthouse (where there is anotherwireless-telegraphy installation), and she is about ten miles from theshore, being directly opposite Deal. The information regarding thecollision was at once communicated by wireless telegraphy from thedisabled lightship to the South Foreland Lighthouse, where Mr. Bullock, assistant to Signor Marconi, received the following message: "We havejust been run into by the steamer _R. F. Matthews_ of London. Steamshipis standing by us. Our bows very badly damaged. " Mr. Bullock immediatelyforwarded this information to the Trinity House authorities atRamsgate. --_Times_, April 29, 1899. 

ELECTRICITY, WHAT ITS MASTERY MEANS: WITH A REVIEW AND A PROSPECT

GEORGE ILES

 [From "Flame, Electricity and the Camera, " copyright by Doubleday, Page & Co. , New York. ]

With the mastery of electricity man enters upon his first realsovereignty of nature. As we hear the whirr of the dynamo or listen atthe telephone, as we turn the button of an incandescent lamp or travelin an electromobile, we are partakers in a revolution more swift andprofound than has ever before been enacted upon earth. Until thenineteenth century fire was justly accounted the most useful andversatile servant of man. To-day electricity is doing all that fire everdid, and doing it better, while it accomplishes uncounted tasks farbeyond the reach of flame, however ingeniously applied. We may thusobserve under our eyes just such an impetus to human intelligence andpower as when fire was first subdued to the purposes of man, with theimmense advantage that, whereas the subjugation of fire demanded ages ofweary and uncertain experiment, the mastery of electricity is, for themost part, the assured work of the nineteenth century, and, in truth, very largely of its last three decades. The triumphs of the electricianare of absorbing interest in themselves, they bear a higher significanceto the student of man as a creature who has gradually come to be what heis. In tracing the new horizons won by electric science and art, a beamof light falls on the long and tortuous paths by which man rose to hissupremacy long before the drama of human life had been chronicled orsung. 

Of the strides taken by humanity on its way to the summit of terrestriallife, there are but four worthy of mention as preparing the way for thevictories of the electrician--the attainment of the upright attitude, the intentional kindling of fire, the maturing of emotional cries toarticulate speech, and the invention of written symbols for speech. Aswe examine electricity in its fruitage we shall find that it bears theunfailing mark of every other decisive factor of human advance: itsmastery is no mere addition to the resources of the race, but amultiplier of them. The case is not as when an explorer discovers aplant hitherto unknown, such as Indian corn, which takes its placebeside rice and wheat as a new food, and so measures a service whichends there. Nor is it as when a prospector comes upon a new metal, suchas nickel, with the sole effect of increasing the variety of materialsfrom which a smith may fashion a hammer or a blade. Almost infinitelyhigher is the benefit wrought when energy in its most useful phase is, for the first time, subjected to the will of man, with dawning knowledgeof its unapproachable powers. It begins at once to marry the resourcesof the mechanic and the chemist, the engineer and the artist, with issueattested by all its own fertility, while its rays reveal province afterprovince undreamed of, and indeed unexisting, before its advent. 

Every other primal gift of man rises to a new height at the bidding ofthe electrician. All the deftness and skill that have followed from theupright attitude, in its creation of the human hand, have been broughtto a new edge and a broader range through electric art. Between the usesof flame and electricity have sprung up alliances which have created newwealth for the miner and the metal-worker, the manufacturer and theshipmaster, with new insights for the man of research. Articulate speechborne on electric waves makes itself heard half-way across America, andwords reduced to the symbols of symbols--expressed in the perforationsof a strip of paper--take flight through a telegraph wire at twenty-foldthe pace of speech. Because the latest leap in knowledge and faculty hasbeen won by the electrician, he has widened the scientific outlookvastly more than any explorer who went before. Beyond any predecessor, he began with a better equipment and a larger capital to prove thegainfulness which ever attends the exploiting a supreme agent ofdiscovery. 

As we trace a few of the unending interlacements of electrical scienceand art with other sciences and arts, and study their mutuallystimulating effects, we shall be reminded of a series of permutationswhere the latest of the factors, because latest, multiplies all priorfactors in an unexampled degree. [5] We shall find reason to believe thatthis is not merely a suggestive analogy, but really true as a tendency, not only with regard to man's gains by the conquest of electricity, butalso with respect to every other signal victory which has brought him tohis present pinnacle of discernment and rule. If this permutativeprinciple in former advances lay undetected, it stands forth clearly inthat latest accession to skill and interpretation which has been usheredin by Franklin and Volta, Faraday and Henry. 

Although of much less moment than the triumphs of the electrician, thediscovery of photography ranks second in importance among the scientificfeats of the nineteenth century. The camera is an artificial eye withalmost every power of the human retina, and with many that are deniedto vision--however ingeniously fortified by the lens-maker. A briefoutline of photographic history will show a parallel to the permutativeimpulse so conspicuous in the progress of electricity. At the pointswhere the electrician and the photographer collaborate we shall noteachievements such as only the loftiest primal powers may evoke. 

A brief story of what electricity and its necessary precursor, fire, have done and promise to do for civilization, may have attraction initself; so, also, may a review, though most cursory, of the work of thecamera and all that led up to it: for the provinces here are as wide asart and science, and their bounds comprehend well-nigh the entirety ofhuman exploits. And between the lines of this story we may readanother--one which may tell us something of the earliest stumblings inthe dawn of human faculty. When we compare man and his next of kin, wefind between the two a great gulf, surely the widest betwixt any alliedfamilies in nature. Can a being of intellect, conscience, and aspirationhave sprung at any time, however remote, from the same stock as theorang and the chimpanzee? Since 1859, when Darwin published his "Originof Species, " the theory of evolution has become so generally acceptedthat to-day it is little more assailed than the doctrine of gravitation. And yet, while the average man of intelligence bows to the formula thatall which now exists has come from the simplest conceivable state ofthings, --a universal nebula, if you will, --in his secret soul he makesone exception--himself. That there is a great deal more assent thanconviction in the world is a chiding which may come as justly from theteacher's table as from the preacher's pulpit. Now, if we but catch themeaning of man's mastery of electricity, we shall have light upon hisearlier steps as a fire-kindler, and as a graver of pictures and symbolson bone and rock. As we thus recede from civilization to primevalsavagery, the process of the making of man may become so clear that thearguments of Darwin shall be received with conviction, and not withsilent repulse. 

As we proceed to recall, one by one, the salient chapters in the historyof fire, and of the arts of depiction that foreran the camera, we shallperceive a truth of high significance. We shall see that, while everynew faculty has its roots deep in older powers, and while its growth mayhave been going on for age after age, yet its flowering may be as theevent of a morning. Even as our gardens show us the century-plants, oncesupposed to bloom only at the end of a hundred years, so history, in thelarge, exhibits discoveries whose harvests are gathered only after thelapse of æons instead of years. The arts of fire were slowly elaborateduntil man had produced the crucible and the still, through which hislabours culminated in metals purified, in acids vastly more corrosivethan those of vegetation, in glass and porcelain equally resistant toflame and the electric wave. These were combined in an hour by Volta tobuild his cell, and in that hour began a new era for human faculty andinsight. 

It is commonly imagined that the progress of humanity has been at atolerably uniform pace. Our review of that progress will show that hereand there in its course have been _leaps_, as radically new forces havebeen brought under the dominion of man. We of the electric revolutionare sharply marked off from our great-grandfathers, who looked upon thecell of Volta as a curious toy. They, in their turn, were profoundlydifferenced from the men of the seventeenth century, who had not learnedthat flame could outvie the horse as a carrier, and grind wheat betterthan the mill urged by the breeze. And nothing short of an abyssstretches between these men and their remote ancestors, who had notfound a way to warm their frosted fingers or lengthen with lamp orcandle the short, dark days of winter. 

Throughout the pages of this book there will be some recital of thevictories won by the fire-maker, the electrician, the photographer, andmany more in the peerage of experiment and research. Underlying thesketch will appear the significant contrast betwixt accessions of minorand of supreme dignity. The finding a new wood, such as that of the yew, means better bows for the archer, stronger handles for the tool-maker;the subjugation of a universal force such as fire, or electricity, stands for the exaltation of power in every field of toil, for thecreation of a new earth for the worker, new heavens for the thinker. Asa corollary, we shall observe that an increasing width of gap marks offthe successive stages of human progress from each other, so that itslatest stride is much the longest and most decisive. And it will befurther evident that, while every new faculty is of age-long derivationfrom older powers and ancient aptitudes, it nevertheless comes to thebirth in a moment, as it were, and puts a strain of probably fatalseverity on those contestants who miss the new gift by however little. We shall, therefore, find that the principle of permutation, here merelyindicated, accounts in large measure for three cardinal facts in thehistory of man: First, his leaps forward; second, the constantaccelerations in these leaps; and third, the gap in the record of thetribes which, in the illimitable past, have succumbed as forces of a newedge and sweep have become engaged in the fray. [6]

The interlacements of the arts of fire and of electricity are intimateand pervasive. While many of the uses of flame date back to the dawn ofhuman skill, many more have become of new and higher value within thelast hundred years. Fire to-day yields motive power with tenfold theeconomy of a hundred years ago, and motive power thus derived is themain source of modern electric currents. In metallurgy there has longbeen an unwitting preparation for the advent of the electrician, andhere the services of fire within the nineteenth century have wontriumphs upon which the later successes of electricity largely proceed. In producing alloys, and in the singular use of heat to effect its ownbanishment, novel and radical developments have been recorded within thepast decade or two. These, also, make easier and bolder theelectrician's tasks. The opening chapters of this book will, therefore, bestow a glance at the principal uses of fire as these have beenrevealed and applied. This glance will make clear how fire andelectricity supplement each other with new and remarkable gains, whilein other fields, not less important, electricity is nothing else than asupplanter of the very force which made possible its own discovery andimpressment. 

[Here follow chapters which outline the chief applications of flame andof electricity. ]

Let us compare electricity with its precursor, fire, and we shallunderstand the revolution by which fire is now in so many taskssupplanted by the electric pulse which, the while, creates for itself athousand fields denied to flame. Copper is an excellent thermalconductor, and yet it transmits heat almost infinitely more slowly thanit conveys electricity. One end of a thick copper rod ten feet long maybe safely held in the hand while the other end is heated to redness, yet one millionth part of this same energy, if in the form ofelectricity, would traverse the rod in one 100, 000, 000th part of asecond. Compare next electricity with light, often the companion ofheat. Light travels in straight lines only; electricity can go round acorner every inch for miles, and, none the worse, yield a brilliant beamat the end of its journey. Indirectly, therefore, electricity enables usto conduct either heat or light as if both were flexible pencils ofrays, and subject to but the smallest tolls in their travel. 

We have remarked upon such methods as those of the electric welder whichsummon intense heat without fire, and we have glanced at the electriclamps which shine just because combustion is impossible through theirrigid exclusion of air. Then for a moment we paused to look at theplating baths which have developed themselves into a commanding rivalrywith the blaze of the smelting furnace, with the flame which from timeimmemorial has filled the ladle of the founder and moulder. Thus methodsthat commenced in dismissing flame end boldly by dispossessing heatitself. But, it may be said, this usurping electricity usually finds itssource, after all, in combustion under a steam-boiler. True, but markthe harnessing of Niagara, of the Lachine Rapids near Montreal, of athousand streams elsewhere. In the near future motive power of Nature'sgiving is to be wasted less and less, and perforce will more and moreexclude heat from the chain of transformations which issue in thelocomotive's flight, in the whirl of factory and mill. Thus in somedegree is allayed the fear, never well grounded, that when the coalfields of the globe are spent civilization must collapse. As theelectrician hears this foreboding he recalls how much fuel is wasted inconverting heat into electricity. He looks beyond either turbine orshaft turned by wind or tide, and, remembering that the metal dissolvedin his battery yields at his will its full content of energy, either asheat or electricity, he asks, Why may not coal or forest tree, which arebut other kinds of fuel, be made to do the same?

One of the earliest uses of light was a means of communicatingintelligence, and to this day the signal lamp and the red fire of themariner are as useful as of old. But how much wider is the field ofelectricity as it creates the telegraph and the telephone! In thetelegraph we have all that a pencil of light could be were it as long asan equatorial girdle and as flexible as a silken thread. In thetelephone for nearly two thousand miles the pulsations of the speaker'svoice are not only audible, but retain their characteristic tones. 

In the field of mechanics electricity is decidedly preferable to anyother agent. Heat may be transformed into motive power by a suitableengine, but there its adaptability is at an end. An electric currentdrives not only a motor, but every machine and tool attached to themotor, the whole executing tasks of a delicacy and complication new toindustrial art. On an electric railroad an identical current propels thetrain, directs it by telegraph, operates its signals, provides it withlight and heat, while it stands ready to give constant verbalcommunication with any station on the line, if this be desired. 

In the home electricity has equal versatility, at once promotinghealthfulness, refinement and safety. Its tiny button expels thehazardous match as it lights a lamp which sends forth no baleful fumes. An electric fan brings fresh air into the house--in summer as a gratefulbreeze. Simple telephones, quite effective for their few yards of wire, give a better because a more flexible service than speaking-tubes. Fewinvalids are too feeble to whisper at the light, portable ear of metal. Sewing-machines and the more exigent apparatus of the kitchen andlaundry transfer their demands from flagging human muscles to thetireless sinews of electric motors--which ask no wages when they standunemployed. Similar motors already enjoy favour in working the elevatorsof tall dwellings in cities. If a householder is timid about burglars, the electrician offers him a sleepless watchman in the guise of anautomatic alarm; if he has a dread of fire, let him dispose on his wallsan array of thermometers that at the very inception of a blaze willstrike a gong at headquarters. But these, after all, are matters ofminor importance in comparison with the foundations upon which may bereared, not a new piece of mechanism, but a new science or a new art. 

In the recent swift subjugation of the territory open alike to thechemist and the electrician, where each advances the quicker for theother's company, we have fresh confirmation of an old truth--that theboundary lines which mark off one field of science from another arepurely artificial, are set up only for temporary convenience. Thechemist has only to dig deep enough to find that the physicist andhimself occupy common ground. "Delve from the surface of your sphere toits heart, and at once your radius joins every other. " Even the briefestglance at electro-chemistry should pause to acknowledge its profounddebt to the new theories as to the bonding of atoms to form molecules, and of the continuity between solution and electrical dissociation. However much these hypotheses may be modified as more light is shed onthe geometry and the journeyings of the molecule, they have for the timebeing recommended themselves as finder-thoughts of golden value. Thesespeculations of the chemist carry him back perforce to the days of hischildhood. As he then joined together his black and white bricks hefound that he could build cubes of widely different patterns. It was inpropounding a theory of molecular architecture that Kekulé gave animpetus to a vast and growing branch of chemical industry--that of thesynthetic production of dyes and allied compounds. 

It was in pure research, in paths undirected to the market-place, thatsuch theories have been thought out. Let us consider electricity as anaid to investigation conducted for its own sake. The chief physicalgeneralization of our time, and of all time, the persistence of force, emerged to view only with the dawn of electric art. When it was observedthat electricity might become heat, light, chemical action, ormechanical motion, that in turn any of these might produce electricity, it was at once indicated that all these phases of energy might differfrom each other only as the movements in circles, volutes, and spiralsof ordinary mechanism. The suggestion was confirmed when electricalmeasurers were refined to the utmost precision, and a single quantum ofenergy was revealed a very Proteus in its disguises, yet beneath thesedisguises nothing but constancy itself. 

"There is that scattereth, and yet increaseth; and there is thatwithholdeth more than is meet, but it tendeth to poverty. " Because thegeometers of old patiently explored the properties of the triangle, thecircle, and the ellipse, simply for pure love of truth, they laid thecorner-stones for the arts of the architect, the engineer, and thenavigator. In like manner it was the disinterested work of investigationconducted by Ampère, Faraday, Henry and their compeers, in ascertainingthe laws of electricity which made possible the telegraph, thetelephone, the dynamo, and the electric furnace. The vital relationsbetween pure research and economic gain have at last worked themselvesclear. It is perfectly plain that a man who has it in him to discoverlaws of matter and energy does incomparably more for his kind than if hecarried his talents to the mint for conversion into coin. The voyage ofa Columbus may not immediately bear as much fruit as the uncoverings ofa mine prospector, but in the long run a Columbus makes possible thefinding many mines which without him no prospector would ever see. Therefore let the seed-corn of knowledge be planted rather than eaten. But in choosing between one research and another it is impossible toforetell which may prove the richer in its harvests; for instance, allattempts thus far economically to oxidize carbon for the production ofelectricity have failed, yet in observations that at first seemedequally barren have lain the hints to which we owe the incandescent lampand the wireless telegraph. 

Perhaps the most promising field of electrical research is that ofdischarges at high pressures; here the leading American investigatorsare Professor John Trowbridge and Professor Elihu Thomson. Employing atension estimated at one and a half millions volts, Professor Trowbridgehas produced flashes of lightning six feet in length in atmospheric air;in a tube exhausted to one-seventh of atmospheric pressure the flashesextended themselves to forty feet. According to this inquirer, thefamiliar rending of trees by lightning is due to the intense heatdeveloped in an instant by the electric spark; the sudden expansion ofair or steam in the cavities of the wood causes an explosion. Theexperiments of Professor Thomson confront him with some of the seemingcontradictions which ever await the explorer of new scientificterritory. In the atmosphere an electrical discharge is facilitated whena metallic terminal (as a lightning rod) is shaped as a point; under oila point is the form least favourable to discharge. In the same line ofparadox it is observed that oil steadily improves in its insulatingeffect the higher the electrical pressure committed to its keeping; withair as an insulator the contrary is the fact. These and a goodly arrayof similar puzzles will, without doubt, be cleared up as students in thetwentieth century pass from the twilight of anomaly to the sunshine ofascertained law. 

"Before there can be applied science there must be science to apply, "and it is by enabling the investigator to know nature under a freshaspect that electricity rises to its highest office. The laboratoryroutine of ascertaining the conductivity, polarisability, and otherelectrical properties of matter is dull and exacting work, but it opensto the student new windows through which to peer at the architecture ofmatter. That architecture, as it rises to his view, discloses one law ofstructure after another; what in a first and clouded glance seemedanomaly is now resolved and reconciled; order displays itself whereonce anarchy alone appeared. When the investigator now needs a substanceof peculiar properties he knows where to find it, or has a hint for itscreation--a creation perhaps new in the history of the world. As hethinks of the wealth of qualities possessed by his store of alloys, salts, acids, alkalies, new uses for them are borne into his mind. Yetmore--a new orchestration of inquiry is possible by means of theinstruments created for him by the electrician, through the advances inmethod which these instruments effect. With a second and more intimatepoint of view arrives a new trigonometry of the particle, a trigonometryinconceivable in pre-electric days. Hence a surround is in progresswhich early in the twentieth century may go full circle, making atom andmolecule as obedient to the chemist as brick and stone are to thebuilder now. 

The laboratory investigator and the commercial exploiter of hisdiscoveries have been by turns borrower and lender, to the great profitof both. What Leyden jar could ever be constructed of the size andrevealing power of an Atlantic cable? And how many refinements ofmeasurement, of purification of metals, of precision in manufacture, have been imposed by the colossal investments in deep-sea telegraphyalone! When a current admitted to an ocean cable, such as that betweenBrest and New York, can choose for its path either 3, 540 miles of copperwire or a quarter of an inch of gutta-percha, there is a dangerousopportunity for escape into the sea, unless the current is of nicelyadjusted strength, and the insulator has been made and laid with thebest-informed skill, the most conscientious care. In the constant testsrequired in laying the first cables Lord Kelvin (then Professor WilliamThomson) felt the need for better designed and more sensitivegalvanometers or current measurers. His great skill both as amathematician and a mechanician created the existing instruments, whichseem beyond improvement. They serve not only in commerce andmanufacture, but in promoting the strictly scientific work of thelaboratory. Now that electricity purifies copper as fire cannot, themathematician is able to treat his problems of long-distancetransmission, of traction, of machine design, with an economy andcertainty impossible when his materials were not simply impure, butimpure in varying and indefinite degrees. The factory and the workshoporiginally took their magneto-machines from the experimental laboratory;they have returned them remodelled beyond recognition as dynamos andmotors of almost ideal effectiveness. 

A galvanometer actuated by a thermo-electric pile furnishes much themost sensitive means of detecting changes of temperature; henceelectricity enables the physicist to study the phenomena of heat withnew ease and precision. It was thus that Professor Tyndall conductedthe classical researches set forth in his "Heat as a Mode of Motion, "ascertaining the singular power to absorb terrestrial heat which makesthe aqueous vapours of the atmosphere act as an indispensable blanket tothe earth. 

And how vastly has electricity, whether in the workshop or laboratory, enlarged our conceptions of the forces that thrill space, of thesubstances, seemingly so simple, that surround us--substances thatpropound questions of structure and behaviour that silence the acutestinvestigator. "You ask me, " said a great physicist, "if I have a theoryof the _universe_? Why, I haven't even a theory of _magnetism_!"

The conventional phrase "conducting a current" is now understood to bemere figure of speech; it is thought that a wire does little else thangive direction to electric energy. Pulsations of high tension have beenproved to be mainly superficial in their journeys, so that they are bestconveyed (or convoyed) by conductors of tubular form. And what is itthat moves when we speak of conduction? It seems to be now the moleculeof atomic chemistry, and anon the same ether that undulates with lightor radiant heat. Indeed, the conquest of electricity means so muchbecause it impresses the molecule and the ether into service as itsvehicles of communication. Instead of the old-time masses of metal, orbands of leather, which moved stiffly through ranges comparativelyshort, there is to-day employed a medium which may traverse 186, 400miles in a second, and with resistances most trivial in contrast withthose of mechanical friction. 

And what is friction in the last analysis but the production of motionin undesired forms, the allowing valuable energy to do useless work? Inthat amazing case of long distance transmission, common sunshine, asolar beam arrives at the earth from the sun not one whit the weaker forits excursion of 92, 000, 000 miles. It is highly probable that we aresurrounded by similar cases of the total absence of friction in thephenomena of both physics and chemistry, and that art will come nearerand nearer to nature in this immunity is assured when we see how manysteps in that direction have already been taken by the electricalengineer. In a preceding page a brief account was given of the theorythat gases and vapours are in ceaseless motion. This motion suffers noabatement from friction, and hence we may infer that the moleculesconcerned are perfectly elastic. The opinion is gaining ground amongphysicists that all the properties of matter, transparency, chemicalcombinability, and the rest, are due to immanent motion in particularorbits, with diverse velocities. If this be established, then thesemotions also suffer no friction, and go on without resistance forever. 

As the investigators in the vanguard of science discuss the constitutionof matter, and weave hypotheses more or less fruitful as to theinterplay of its forces, there is a growing faith that the day is athand when the tie between electricity and gravitation will beunveiled--when the reason why matter has weight will cease to puzzle thethinker. Who can tell what relief of man's estate may be bound up withthe ability to transform any phase of energy into any other without thecircuitous methods and serious losses of to-day! In the sphere ofeconomic progress one of the supreme advances was due to the inventionof money, the providing a medium for which any salable thing may beexchanged, with which any purchasable thing may be bought. As soon as ashell, or a hide, or a bit of metal was recognized as having universalconvertibility, all the delays and discounts of barter were at an end. In the world of physics and chemistry the corresponding medium iselectricity; let it be produced as readily as it produces other modes ofmotion, and human art will take a stride forward such as when Voltadisposed his zinc and silver discs together, or when Faraday set amagnet moving around a copper wire. 

For all that the electric current is not as yet produced as economicallyas it should be, we do wrong if we regard it as an infant force. Howevermuch new knowledge may do with electricity in the laboratory, in thefactory, or in the exchange, some of its best work is already done. Itis not likely ever to perform a greater feat than placing all mankindwithin ear-shot of each other. Were electricity unmastered there couldbe no democratic government of the United States. To-day the drama ofnational affairs is more directly in view of every American citizenthan, a century ago, the public business of Delaware could be to the menof that little State. And when on the broader stage of internationalpolitics misunderstandings arise, let us note how the telegraph hasmodified the hard-and-fast rules of old-time diplomacy. To-day, throughthe columns of the press, the facts in controversy are instantlypublished throughout the world, and thus so speedily give rise toauthoritative comment that a severe strain is put upon negotiators whosetradition it is to be both secret and slow. 

Railroads, with all they mean for civilization, could not have extendedthemselves without the telegraph to control them. And railroads andtelegraphs are the sinews and nerves of national life, the primeagencies in welding the diverse and widely separated States andTerritories of the Union. A Boston merchant builds a cotton-mill inGeorgia; a New York capitalist opens a copper-mine in Arizona. Thetelegraph which informs them day by day how their investments prospertells idle men where they can find work, where work can seek idle men. Chicago is laid in ashes, Charleston topples in earthquake, Johnstown iswhelmed in flood, and instantly a continent springs to their relief. Andwhat benefits issue in the strictly commercial uses of the telegraph!At its click both locomotive and steamship speed to the relief of faminein any quarter of the globe. In times of plenty or of dearth the marketsof the globe are merged and are brought to every man's door. Not lessstriking is the neighbourhood guild of science, born, too, of thetelegraph. The day after Röntgen announced his X rays, physicists onevery continent were repeating his experiments--were applying hisdiscovery to the healing of the wounded and diseased. Let an anti-toxinfor diphtheria, consumption, or yellow fever be proposed, and a hundredinvestigators the world over bend their skill to confirm or disprove, asif the suggester dwelt next door. 

On a stage less dramatic, or rather not dramatic at all, electricityworks equal good. Its motor freeing us from dependence on the horse isspreading our towns and cities into their adjoining country. Field andgarden compete with airless streets. The sunny cottage is in activerivalry with the odious tenement-house. It is found that transportationwithin the gates of a metropolis has an importance second only to themeans of transit which links one city with another. The engineer is atlast filling the gap which too long existed between the traction ofhorses and that of steam. In point of speed, cleanliness, and comfortsuch an electric subway as that of South London leaves nothing to bedesired. Throughout America electric roads, at first suburban, are nowfast joining town to town and city to city, while, as auxiliaries tosteam railroads, they place sparsely settled communities in the arterialcurrent of the world, and build up a ready market for the dairyman andthe fruit-grower. In its saving of what Mr. Oscar T. Crosby has called"man-hours" the third-rail system is beginning to oust steam as a motivepower from trunk-lines. Already shrewd railroad managers are grantingpartnerships to the electricians who might otherwise encroach upon theirdividends. A service at first restricted to passengers has now extendeditself to the carriage of letters and parcels, and begins to reach outfor common freight. We may soon see the farmer's cry for good roadssatisfied by good electric lines that will take his crops to market muchmore cheaply and quickly than horses and macadam ever did. In cities, electromobile cabs and vans steadily increase in numbers, furthering thequiet and cleanliness introduced by the trolley car. 

A word has been said about the blessings which electricity promises tocountry folk, yet greater are the boons it stands ready to bestow in thehives of population. Until a few decades ago the water-supply of citieswas a matter not of municipal but of individual enterprise; water wasdrawn in large part from wells here and there, from lines of piping laidin favoured localities, and always insufficient. Many an epidemic oftyphoid fever was due to the contamination of a spring by a cesspool afew yards away. To-day a supply such as that of New York is abundantand cheap because it enters every house. Let a centralized electricalservice enjoy a like privilege, and it will offer a current which isheat, light, chemical energy, or motive power, and all at a wage lowerthan that of any other servant. Unwittingly, then, the electricalengineer is a political reformer of high degree, for he puts a newpremium upon ability and justice at the City Hall. His sole condition isthat electricity shall be under control at once competent and honest. Let us hope that his plea, joined to others as weighty, may quicken thespirit of civic righteousness so that some of the richest fruits everborne in the garden of science and art may not be proffered in vain. Flame, the old-time servant, is individual; electricity, its successorand heir, is collective. Flame sits upon the hearth and draws a familytogether; electricity, welling from a public source, may bind into aunit all the families of a vast city, because it makes the benefit ofeach the interest of all. 

But not every promise brought forward in the name of the electrician hashis assent or sanction. So much has been done by electricity, and somuch more is plainly feasible, that a reflection of its triumphs hasgilded many a baseless dream. One of these is that the cheap electricmotor, by supply power at home, will break up the factory system, andbring back the domestic manufacturing of old days. But if this powercost nothing at all the gift would leave the factory unassailed; for wemust remember that power is being steadily reduced in cost from year toyear, so that in many industries it has but a minor place among theexpenses of production. The strength and profit of the factory systemlie in its assembling a wide variety of machines, the first deliveringits product to the second for another step toward completion, and so onuntil a finished article is sent to the ware-room. It is this minutesubdivision of labour, together with the saving and efficiency thatinure to a business conducted on an immense scale under a singlemanager, that bids us believe that the factory has come to stay. To besure, a weaver, a potter, or a lens-grinder of peculiar skill may thriveat his loom or wheel at home; but such a man is far from typical inmodern manufacture. Besides, it is very questionable whether thelamentations over the home industries of the past do not ignore evilconcomitants such as still linger in the home industries of thepresent--those of the sweater's den, for example. 

This rapid survey of what electricity has done and may yet do--futileexpectation dismissed--has shown it the creator of a thousand materialresources, the perfector of that communication of things, of power, ofthought, which in every prior stage of advancement has marked thesuccessive lifts of humanity. It was much when the savage loaded a packupon a horse or an ox instead of upon his own back; it was yet more whenhe could make a beacon-flare give news or warning to a wholecountry-side, instead of being limited to the messages which might beread in his waving hands. All that the modern engineer was able to dowith steam for locomotion is raised to a higher plane by the advent ofhis new power, while the long-distance transmission of electrical energyis contracting the dimensions of the planet to a scale upon which itscataracts in the wilderness drive the spindles and looms of the factorytown, or illuminate the thoroughfares of cities. Beyond and above allsuch services as these, electricity is the corner-stone of physicalgeneralization, a revealer of truths impenetrable by any other ray. 

The subjugation of fire has done much in giving man a new independenceof nature, a mighty armoury against evil. In curtailing the most arduousand brutalizing forms of toil, electricity, that subtler kind of fire, carries this emancipation a long step further, and, meanwhile, bestowsupon the poor many a luxury which but lately was the exclusivepossession of the rich. In more closely binding up the good of the beewith the welfare of the hive, it is an educator and confirmer of everysocial bond. In so far as it proffers new help in the war on pain anddisease it strengthens the confidence of man in an Order of Right andHappiness which for so many dreary ages has been a matter rather of hopethan of vision. Are we not, then, justified in holding electricity to bea multiplier of faculty and insight, a means of dignifying mind andsoul, unexampled since man first kindled fire and rejoiced?

We have traced how dexterity rose to fire-making, how fire-making led tothe subjugation of electricity. Much of the most telling work of firecan be better done by its great successor, while electricity performsmany tasks possible only to itself. Unwitting truth there was in thesimple fable of the captive who let down a spider's film, that drew up athread, which in turn brought up a rope--and freedom. It was in 1800 onthe threshold of the nineteenth century, that Volta devised the firstelectric battery. In a hundred years the force then liberated hasvitally interwoven itself with every art and science, bearing fruit notto be imagined even by men of the stature of Watt, Lavoisier, orHumboldt. Compare this rapid march of conquest with the slow adaptation, through age after age, of fire to cooking, smelting, tempering. Yet itwas partly, perhaps mainly, because the use of fire had drawn out man'sintelligence and cultivated his skill that he was ready in the fulnessof time so quickly to seize upon electricity and subdue it. 

Electricity is as legitimately the offspring of fire as fire of thesimple knack in which one savage in ten thousand was richer than hisfellows. The principle of permutation, suggested in both victories, interprets not only how vast empire is won by a new weapon of primedignity; it explains why such empires are brought under rule withever-accelerated pace. Every talent only pioneers the way for thericher talents which are born from it. 

FOOTNOTES:

[5] Permutations are the various ways in which two or more differentthings may be arranged in a row, all the things appearing in each row. Permutations are readily illustrated with squares or cubes of differentcolours, with numbers, or letters. 

Permutations of two elements, 1 and 2, are (1 x 2) two; 1, 2; 2, 1; or_a_, _b_; _b_, _a_. Of three elements the permutations are (1 x 2 x 3)six; 1, 2, 3; 1, 3, 2; 2, 1, 3; 2, 3, 1; 3, 1, 2; 3, 2, 1; or _a_, _b_, _c_; _a_, _c_, _b_; _b_, _a_, _c_; _b_, _c_, _a_; _c_, _a_, _b_; _c_, _b_, _a_. Of four elements the permutations are (1 x 2 x 3 x 4)twenty-four; of five elements, one hundred and twenty, and so on. A newelement or permutator multiplies by an increasing figure all thepermutations it finds. 

[6] Some years ago I sent an outline of this argument to HerbertSpencer, who replied: "I recognize a novelty and value in your inferencethat the law implies an increasing width of gap between lower and highertypes as evolution advances. "

COUNT RUMFORD IDENTIFIES HEAT WITH MOTION. 

 [Benjamin Thompson, who received the title of Count Rumford from the Elector of Bavaria, was born in Woburn, Massachusetts, in 1753. When thirty-one years of age he settled in Munich, where he devoted his remarkable abilities to the public service. Twelve years afterward he removed to England; in 1800 he founded the Royal Institution of London, since famous as the theatre of the labours of Davy, Faraday, Tyndall, and Dewar. He bequeathed to Harvard University a fund to endow a professorship of the application of science to the art of living: he instituted a prize to be awarded by the American Academy of Sciences for the most important discoveries and improvements relating to heat and light. In 1804 he married the widow of the illustrious chemist Lavoisier: he died in 1814. Count Rumford on January 25, 1798, read a paper before the Royal Society entitled "An Enquiry Concerning the Source of Heat Which Is Excited by Friction. " The experiments therein detailed proved that heat is identical with motion, as against the notion that heat is matter. He thus laid the corner-stone of the modern theory that heat light, electricity, magnetism, chemical action, and all other forms of energy are in essence motion, are convertible into one another, and as motion are indestructible. The following abstract of Count Rumford's paper is taken from "Heat as a Mode of Motion, " by Professor John Tyndall, published by D. Appleton & Co. , New York. This work and "The Correlation and Conservation of Forces, " edited by Dr. E. L. Youmans, published by the same house, will serve as a capital introduction to the modern theory that energy is motion which, however varied in its forms, is changeless in its quantity. ]

Being engaged in superintending the boring of cannon in the workshops ofthe military arsenal at Munich, Count Rumford was struck with the veryconsiderable degree of heat which a brass gun acquires, in a short time, in being bored, and with the still more intense heat (much greater thanthat of boiling water) of the metallic chips separated from it by theborer, he proposed to himself the following questions:

"Whence comes the heat actually produced in the mechanical operationsabove mentioned?

"Is it furnished by the metallic chips which are separated from themetal?"

If this were the case, then the _capacity for heat_ of the parts of themetal so reduced to chips ought not only to be changed, but the changeundergone by them should be sufficiently great to account for _all_ theheat produced. No such change, however, had taken place, for the chipswere found to have the same capacity as slices of the same metal cut bya fine saw, where heating was avoided. Hence, it is evident, that theheat produced could not possibly have been furnished at the expense ofthe latent heat of the metallic chips. Rumford describes theseexperiments at length, and they are conclusive. 

He then designed a cylinder for the express purpose of generating heatby friction, by having a blunt borer forced against its solid bottom, while the cylinder was turned around its axis by the force of horses. Tomeasure the heat developed, a small round hole was bored in thecylinder for the purpose of introducing a small mercurial thermometer. The weight of the cylinder was 113. 13 pounds avoirdupois. 

The borer was a flat piece of hardened steel, 0. 63 of an inch thick, four inches long, and nearly as wide as the cavity of the bore of thecylinder, namely, three and one-half inches. The area of the surface bywhich its end was in contact with the bottom of the bore was nearly twoand one-half inches. At the beginning of the experiment the temperatureof the air in the shade, and also that of the cylinder, was 60° Fahr. Atthe end of thirty minutes, and after the cylinder had made 960revolutions round its axis, the temperature was found to be 130°. 

Having taken away the borer, he now removed the metallic dust, or ratherscaly matter, which had been detached from the bottom of the cylinder bythe blunt steel borer, and found its weight to be 837 grains troy. "Isit possible, " he exclaims, "that the very considerable quantity of heatproduced in this experiment--a quantity which actually raised thetemperature of above 113 pounds of gun-metal at least 70° ofFahrenheit's thermometer--could have been furnished by so inconsiderablea quantity of metallic dust and this merely in consequence of a _change_in its capacity of heat?"

"But without insisting on the improbability of this supposition, we haveonly to recollect that from the results of actual and decisiveexperiments, made for the express purpose of ascertaining that fact, the capacity for heat for the metal of which great guns are cast is _notsensibly changed_ by being reduced to the form of metallic chips, andthere does not seem to be any reason to think that it can be muchchanged, if it be changed at all, in being reduced to much smallerpieces by a borer which is less sharp. "

He next surrounded his cylinder by an oblong deal-box, in such a mannerthat the cylinder could turn water-tight in the centre of the box, whilethe borer was pressed against the bottom of the cylinder. The box wasfilled with water until the entire cylinder was covered, and then theapparatus was set in action. The temperature of the water on commencingwas 60°. 

"The result of this beautiful experiment, " writes Rumford, "was verystriking, and the pleasure it afforded me amply repaid me for all thetrouble I had had in contriving and arranging the complicated machineryused in making it. The cylinder had been in motion but a short time, when I perceived, by putting my hand into the water, and touching theoutside of the cylinder, that heat was generated. 

"At the end of one hour the fluid, which weighed 18. 77 pounds, or twoand one-half gallons, had its temperature raised forty-seven degrees, being now 107°. 

"In thirty minutes more, or one hour and thirty minutes after themachinery had been set in motion, the heat of the water was 142°. 

"At the end of two hours from the beginning, the temperature was 178°. 

"At two hours and twenty minutes it was 200°, and at two hours andthirty minutes it _actually boiled_!"

"It would be difficult to describe the surprise and astonishmentexpressed in the countenances of the bystanders on seeing so large aquantity of water heated, and actually made to boil, without any fire. Though, there was nothing that could be considered very surprising inthis matter, yet I acknowledge fairly that it afforded me a degree ofchildish pleasure which, were I ambitious of the reputation of a gravephilosopher, I ought most certainly rather to hide than to discover. "

He then carefully estimates the quantity of heat possessed by eachportion of his apparatus at the conclusion of the experiment, and, adding all together, finds a total sufficient to raise 26. 58 pounds ofice-cold water to its boiling point, or through 180° Fahrenheit. Bycareful calculation, he finds this heat equal to that given out by thecombustion of 2, 303. 8 grains (equal to four and eight-tenths ouncestroy) of wax. 

He then determines the "_celerity_" with which the heat was generated, summing up thus: "From the results of these computations, it appearsthat the quantity of heat produced equably, or in a continuous stream, if I may use the expression, by the friction of the blunt steel boreragainst the bottom of the hollow metallic cylinder, was _greater_ thanthat produced in the combustion of nine _wax-candles_, eachthree-quarters of an inch in diameter, all burning together with clearbright flames. 

"One horse would have been equal to the work performed, though two wereactually employed. Heat may thus be produced merely by the strength of ahorse, and, in a case of necessity, this heat might be used in cookingvictuals. But no circumstances could be imagined in which this method ofprocuring heat would be advantageous, for more heat might be obtained byusing the fodder necessary for the support of a horse as fuel. "

[This is an extremely significant passage, intimating as it does, thatRumford saw clearly that the force of animals was derived from the food;_no creation of force_ taking place in the animal body. ]

"By meditating on the results of all these experiments, we are naturallybrought to that great question which has so often been the subject ofspeculation among philosophers, namely, What is heat--is there any suchthing as an _igneous fluid_? Is there anything that, with propriety, canbe called caloric?

"We have seen that a very considerable quantity of heat may be excitedby the friction of two metallic surfaces, and given off in a constantstream or flux _in all directions_, without interruption orintermission, and without any signs of _diminution_ or _exhaustion_. Inreasoning on this subject we must not forget _that most remarkablecircumstance_, that the source of the heat generated by friction inthese experiments appeared evidently to be _inexhaustible_. [The italicsare Rumford's. ] It is hardly necessary to add, that anything which any_insulated_ body or system of bodies can continue to furnish _withoutlimitation_ cannot possibly be a _material substance_; and it appears tome to be extremely difficult, if not quite impossible, to form anydistinct idea of anything capable of being excited and communicated inthose experiments, except it be MOTION. "

When the history of the dynamical theory of heat is written, the manwho, in opposition to the scientific belief of his time, couldexperiment and reason upon experiment, as Rumford did in theinvestigation here referred to, cannot be lightly passed over. Hardlyanything more powerful against the materiality of heat has been sinceadduced, hardly anything more conclusive in the way of establishing thatheat is, what Rumford considered it to be, _Motion_. 

VICTORY OF THE "ROCKET" LOCOMOTIVE. 

 [Part of Chapter XII. Part II, of "The Life of George Stephenson and of His Son, Robert Stephenson, " by Samuel Smiles New York, Harper & Brothers, 1868. ]

The works of the Liverpool and Manchester Railway were now approachingcompletion. But, strange to say, the directors had not yet decided as tothe tractive power to be employed in working the line when open fortraffic. The differences of opinion among them were so great asapparently to be irreconcilable. It was necessary, however, that theyshould, come to some decision without further loss of time, and manyboard meetings were accordingly held to discuss the subject. Theold-fashioned and well-tried system of horse-haulage was not without itsadvocates; but, looking at the large amount of traffic which there wasto be conveyed, and at the probable delay in the transit from station tostation if this method were adopted, the directors, after a visit madeby them to the Northumberland and Durham railways in 1828, came to theconclusion that the employment of horse-power was inadmissible. 

Fixed engines had many advocates; the locomotive very few: it stood asyet almost in a minority of one--George Stephenson.... 

In the meantime the discussion proceeded as to the kind of power to bepermanently employed for the working of the railway. The directors wereinundated with schemes of all sorts for facilitating locomotion. Theprojectors of England, France, and America seemed to be let loose uponthem. There were plans for working the waggons along the line bywater-power. Some proposed hydrogen, and others carbonic acid gas. Atmospheric pressure had its eager advocates. And various kinds of fixedand locomotive steam-power were suggested. Thomas Gray urged his plan ofa greased road with cog-rails; and Messrs. Vignolles and Ericssonrecommended the adoption of a central friction-rail, against which twohorizontal rollers under the locomotive, pressing upon the sides of thisrail, were to afford the means of ascending the inclined planes.... 

The two best practical engineers of the day concurred in reportingsubstantially in favour of the employment of fixed engines. Not a singleprofessional man of eminence could be found to coincide with theengineer of the railway in his preference for locomotive over fixedengine power. He had scarcely a supporter, and the locomotive systemseemed on the eve of being abandoned. Still he did not despair. With theprofession against him, and public opinion against him--for the mostfrightful stories went abroad respecting the dangers, the unsightliness, and the nuisance which the locomotive would create--Stephenson held tohis purpose. Even in this, apparently the darkest hour of thelocomotive, he did not hesitate to declare that locomotive railroadswould, before many years had passed, be "the great highways of theworld. "

He urged his views upon the directors in all ways, in season, and, assome of them thought, out of season. He pointed out the greaterconvenience of locomotive power for the purposes of a public highway, likening it to a series of short unconnected chains, any one of whichcould be removed and another substituted without interruption to thetraffic; whereas the fixed-engine system might be regarded in the lightof a continuous chain extending between the two termini, the failure ofany link of which would derange the whole. But the fixed engine partywas very strong at the board, and, led by Mr. Cropper, they urged thepropriety of forthwith adopting the report of Messrs. Walker andRastrick. Mr. Sandars and Mr. William Rathbone, on the other hand, desired that a fair trial should be given to the locomotive; and theywith reason objected to the expenditure of the large capital necessaryto construct the proposed engine-houses, with their fixed engines, ropes, and machinery, until they had tested the powers of the locomotiveas recommended by their own engineer. George Stephenson continued tourge upon them that the locomotive was yet capable of greatimprovements, if proper inducements were held out to inventors andmachinists to make them; and he pledged himself that, if time weregiven him, he would construct an engine that should satisfy theirrequirements, and prove itself capable of working heavy loads along therailway with speed, regularity, and safety. At length, influenced by hispersistent earnestness not less than by his arguments, the directors, atthe suggestion of Mr. Harrison, determined to offer a prize of £500 forthe best locomotive engine, which, on a certain day, should be producedon the railway, and perform certain specified conditions in the mostsatisfactory manner. [7]

The requirements of the directors as to speed were not excessive. Allthat they asked for was that ten miles an hour should be maintained. Perhaps they had in mind the animadversions of the _Quarterly Review_ onthe absurdity of travelling at a greater velocity, and also the remarkspublished by Mr. Nicholas Wood, whom they selected to be one of thejudges of the competition, in conjunction, with Mr. Rastrick, ofStourbridge, and Mr. Kennedy, of Manchester. 

It was now felt that the fate of railways in a great measure dependedupon the issue of this appeal to the mechanical genius of England. Whenthe advertisement of the prize for the best locomotive was published, scientific men began more particularly to direct their attention to thenew power which was thus struggling into existence. In the meantimepublic opinion on the subject of railway working remained suspended, andthe progress of the undertaking was watched with intense interest. 

During the progress of this important controversy with reference to thekind of power to be employed in working the railway, George Stephensonwas in constant communication with his son Robert, who made frequentvisits to Liverpool for the purpose of assisting his father in thepreparation of his reports to the board on the subject. Mr. Swanwickremembers the vivid interest of the evening discussions which then tookplace between father and son as to the best mode of increasing thepowers and perfecting the mechanism of the locomotive. He wondered attheir quick perception and rapid judgment on each other's suggestions;at the mechanical difficulties which they anticipated and provided forin the practical arrangement of the machine; and he speaks of theseevenings as most interesting displays of two actively ingenious and ableminds stimulating each other to feats of mechanical invention, by whichit was ordained that the locomotive engine should become what it now is. These discussions became more frequent, and still more interesting, after the public prize had been offered for the best locomotive by thedirectors of the railway, and the working plans of the engine which theyproposed to construct had to be settled. 

One of the most important considerations in the new engine was thearrangement of the boiler, and the extension of its heating surface toenable steam enough to be raised rapidly and continuously for thepurpose of maintaining high rates of speed--the effect of high pressureengines being ascertained to depend mainly upon the quantity of steamwhich the boiler can generate, and upon its degree of elasticity whenproduced. The quantity of steam so generated, it will be obvious, mustchiefly depend upon the quantity of fuel consumed in the furnace, and, by necessary consequence, upon the high rate of temperature maintainedthere. 

It will be remembered that in Stephenson's first Killingworth engines heinvited and applied the ingenious method of stimulating combustion inthe furnace by throwing the waste steam into the chimney afterperforming its office in the cylinders, thereby accelerating the ascentof the current of air, greatly increasing the draught, and consequentlythe temperature of the fire. This plan was adopted by him, as we haveseen, as early as 1815, and it was so successful that he himselfattributed to it the greater economy of the locomotive as compared withhorse-power. Hence the continuance of its use upon the KillingworthRailway. 

Though the adoption of the steam blast greatly quickened combustion andcontributed to the rapid production of high-pressure steam, the limitedamount of heating surface presented to the fire was still felt to be anobstacle to the complete success of the locomotive engine. Mr. Stephenson endeavoured to overcome this by lengthening the boilers andincreasing the surface presented by the flue-tubes. The "LancashireWitch, " which he built for the Bolton and Leigh Railway, and used informing the Liverpool and Manchester Railway embankments, wasconstructed with a double tube, each of which contained a fire, andpassed longitudinally through the boiler. But this arrangementnecessarily led to a considerable increase in the weight of thoseengines, which amounted to about twelve tons each; and as six tons wasthe limit allowed for engines admitted to the Liverpool competition, itwas clear that the time was come when the Killingworth engine mustundergo a farther important modification. 

For many years previous to this period, ingenious mechanics had beenengaged in attempting to solve the problem of the best and mosteconomical boiler for the production of high-pressure steam. 

The use of tubes in boilers for increasing the heating surface had longbeen known. As early as 1780, Matthew Boulton employed copper tubeslongitudinally in the boiler of the Wheal Busy engine in Cornwall--thefire passing _through_ the tubes--and it was found that the productionof steam was thereby considerably increased. The use of tubular boilersafterwards became common in Cornwall. In 1803, Woolf, the Cornishengineer, patented a boiler with tubes, with the same object ofincreasing the heating surface. The water was _inside_ the tubes, andthe fire of the boiler outside. Similar expedients were proposed byother inventors. In 1815 Trevithick invented his light high-pressureboiler for portable purposes, in which, to "expose a large surface tothe fire, " he constructed the boiler of a number of small perpendiculartubes "opening into a common reservoir at the top. " In 1823 W. H. Jamescontrived a boiler composed of a series of annular wrought-iron tubes, placed side by side and bolted together, so as to form by their union along cylindrical boiler, in the centre of which, at the end, thefireplace was situated. The fire played round the tubes, which containedthe water. In 1826 James Neville took out a patent for a boiler withvertical tubes surrounded by the water, through which the heated air ofthe furnace passed, explaining also in his specification that the tubesmight be horizontal or inclined, according to circumstances. Mr. Goldsworthy, the persevering adaptor of steam-carriages to travelling oncommon roads, applied the tubular principle in the boiler of his engine, in which the steam was generated _within_ the tubes; while the boilerinvented by Messrs. Summer and Ogle for their turnpike-roadsteam-carriage consisted of a series of tubes placed vertically over thefurnace, through which the heated air passed before reaching thechimney. 

About the same time George Stephenson was trying the effect ofintroducing small tubes in the boilers of his locomotives, with theobject of increasing their evaporative power. Thus, in 1829, he sent toFrance two engines constructed at the Newcastle works for the Lyons andSt. Etienne Railway, in the boilers of which tubes were placedcontaining water. The heating surface was thus considerably increased;but the expedient was not successful, for the tubes, becoming furredwith deposit, shortly burned out and were removed. It was then that M. Seguin, the engineer of the railway, pursuing the same idea, is said tohave adopted his plan of employing horizontal tubes through which theheated air passed in streamlets, and for which he took out a Frenchpatent. 

In the meantime Mr. Henry Booth, secretary to the Liverpool andManchester Railway, whose attention had been directed to the subject onthe prize being offered for the best locomotive to work that line, proposed the same method, which, unknown to him, Matthew Boulton hademployed but not patented, in 1780, and James Neville had patented, butnot employed, in 1826; and it was carried into effect by RobertStephenson in the construction of the "Rocket, " which won the prize atRainhill in October, 1829. The following is Mr. Booth's account in aletter to the author:

"I was in almost daily communication with Mr. Stephenson at the time, and I was not aware that he had any intention of competing for the prizetill I communicated to him my scheme of a multitubular boiler. This newplan of boiler comprised the introduction of numerous small tubes, twoor three inches in diameter, and less than one-eighth of an inch thick, through which to carry the fire instead of a single tube or flueeighteen inches in diameter, and about half an inch thick, by whichplan we not only obtain a very much larger heating surface, but theheating surface is much more effective, as there intervenes between thefire and the water only a thin sheet of copper or brass, not an eighthof an inch thick, instead of a plate of iron of four times thesubstance, as well as an inferior conductor of heat. 

"When the conditions of trial were published, I communicated mymultitubular plan to Mr. Stephenson, and proposed to him that we shouldjointly construct an engine and compete for the prize. Mr. Stephensonapproved the plan, and agreed to my proposal. He settled the mode inwhich the fire-box and tubes were to be mutually arranged and connected, and the engine was constructed at the works of Messrs. Robert Stephenson& Co. , Newcastle-on-Tyne. 

"I am ignorant of M. Seguin's proceedings in France, but I claim to bethe inventor in England, and feel warranted in stating, withoutreservation, that until I named my plan to Mr. Stephenson, with a viewto compete for the prize at Rainhill, it had not been tried, and was notknown in this country. "

From the well-known high character of Mr. Booth, we believe hisstatement to be made in perfect good faith, and that he was as much inignorance of the plan patented by Neville as he was of that of Seguin. As we have seen, from the many plans of tubular boilers invented duringthe preceding thirty years, the idea was not by any means new; and webelieve Mr. Booth to be entitled to the merit of inventing the method bywhich the multitubular principle was so effectually applied in theconstruction of the famous "Rocket" engine. 

The principal circumstances connected with the construction of the"Rocket, " as described by Robert Stephenson to the author, may bebriefly stated. The tubular principle was adopted in a more completemanner than had yet been attempted. Twenty-five copper tubes, each threeinches in diameter, extended from one end of the boiler to the other, the heated air passing through them on its way to the chimney; and thetubes being surrounded by the water of the boiler, it will be obviousthat a large extension of the heating surface was thus effectuallysecured. The principal difficulty was in fitting the copper tubes in theboiler ends so as to prevent leakage. They were manufactured by aNewcastle coppersmith, and soldered to brass screws which were screwedinto the boiler ends, standing out in great knobs. When the tubes werethus fitted, and the boiler was filled with water, hydraulic pressurewas applied; but the water squirted out at every joint, and the factoryfloor was soon flooded. Robert went home in despair; and in the firstmoment of grief he wrote to his father that the whole thing was afailure. By return of post came a letter from his father, telling himthat despair was not to be thought of--that he must "try again;" and hesuggested a mode of overcoming the difficulty, which his son hadalready anticipated and proceeded to adopt. It was, to bore clean holesin the boiler ends, fit in the smooth copper tubes as tightly aspossible, solder up, and then raise the steam. This plan succeededperfectly, the expansion of the copper tubes completely filling up allinterstices, and producing a perfectly water-tight boiler, capable ofwithstanding extreme external pressure. 

The mode of employing the steam-blast for the purpose of increasing thedraught in the chimney was also the subject of numerous experiments. When the engine was first tried, it was thought that the blast in thechimney was not sufficiently strong for the purpose of keeping up theintensity of fire in the furnace, so as to produce high-pressure steamwith the required velocity. The expedient was therefore adopted ofhammering the copper tubes at the point at which they entered thechimney, whereby the blast was considerably sharpened; and on a farthertrial it was found that the draught was increased to such an extent asto enable abundance of steam to be raised. The rationale of the blastmay be simply explained by referring to the effect of contracting thepipe of a water-hose, by which the force of the jet of water isproportionately increased. Widen the nozzle of the pipe, and the jet isin like manner diminished. So it is with the steam-blast in the chimneyof the locomotive. 

Doubts were, however, expressed whether the greater draught obtained bythe contraction of the blast-pipe was not counterbalanced in some degreeby the negative pressure upon the piston. Hence a series of experimentswas made with pipes of different diameters, and their efficiency wastested by the amount of vacuum that was produced in the smoke-box. Thedegree of rarefaction was determined by a glass tube fixed to the bottomof the smoke-box and descending into a bucket of water, the tube beingopen at both ends. As the rarefaction took place, the water would, ofcourse, rise in the tube, and the height to which it rose above thesurface of the water in the bucket was made the measure of the amount ofrarefaction. These experiments proved that a considerable increase ofdraught was obtained by the contraction of the orifice; accordingly, thetwo blast-pipes opening from the cylinders into either side of the"Rocket" chimney, and turned up within it, were contracted slightlybelow the area of the steam-ports, and before the engine left thefactory, the water rose in the glass tube three inches above the waterin the bucket. 

The other arrangements of the "Rocket" were briefly these: the boilerwas cylindrical, with flat ends, six feet in length, and three feet fourinches in diameter. The upper half of the boiler was used as a reservoirfor the steam, the lower half being filled with water. Through the lowerpart the copper tubes extended, being open to the fire-box at one end, and to the chimney at the other. The fire-box, or furnace, two feet wideand three feet high, was attached immediately behind the boiler, and wasalso surrounded with water. The cylinders of the engine were placed oneach side of the boiler, in an oblique position, one end being nearlylevel with the top of the boiler at its after end, and the otherpointing toward the centre of the foremost or driving pair of wheels, with which the connection was directly made from the piston-rod to a pinon the outside of the wheel. The engine, together with its load ofwater, weighed only four tons and a quarter; and it was supported onfour wheels, not coupled. The tender was four-wheeled, and similar inshape to a waggon--the foremost part holding the fuel, and the hind parta water cask. 

When the "Rocket" was finished it was placed upon the KillingworthRailway for the purpose of experiment. The new boiler arrangement wasfound perfectly successful. The steam was raised rapidly andcontinuously, and in a quantity which then appeared marvellous. The sameevening Robert despatched a letter to his father at Liverpool, informinghim, to his great joy, that the "Rocket" was "all right, " and would bein complete working trim by the day of trial. The engine was shortlyafter sent by waggon to Carlisle, and thence shipped for Liverpool. 

The time so much longed for by George Stephenson had now arrived, whenthe merits of the passenger locomotive were about to be put to thetest. He had fought the battle for it until now almost single-handed. Engrossed by his daily labours and anxieties, and harassed bydifficulties and discouragements which would have crushed the spirit ofa less resolute man, he had held firmly to his purpose through good andthrough evil report. The hostility which he experienced from some of thedirectors opposed to the adoption of the locomotive was the circumstancethat caused him the greatest grief of all; for where he had looked forencouragement, he found only carping and opposition. But his pluck neverfailed him; and now the "Rocket" was upon the ground to prove, to usehis own words, "whether he was a man of his word or not. "

On the day appointed for the great competition of locomotives atRainhill the following engines were entered for the prize:

1. Messrs. Braithwaite and Ericsson's "Novelty. "

2. Mr. Timothy Hackworth's "Sanspareil. "

3. Messrs. R. Stephenson & Co. 's "Rocket. "

4. Mr. Burstall's "Perseverance. "

The ground on which the engines were to be tried was a level piece ofrailroad, about two miles in length. Each was required to make twentytrips, or equal to a journey of seventy miles, in the course of the day, and the average rate of travelling was to be not under ten miles anhour. It was determined that, to avoid confusion, each engine should betried separately, and on different days. 

The day fixed for the competition was the 1st of October, but, to allowsufficient time to get the locomotives into good working order, thedirectors extended it to the 6th. It was quite characteristic of theStephensons that, although their engine did not stand first on the listfor trial, it was the first that was ready, and it was accordinglyordered out by the judges for an experimental trip. Yet the "Rocket" wasby no means the "favourite" with either the judges or the spectators. Nicholas Wood has since stated that the majority of the judges werestrongly predisposed in favour of the "Novelty, " and that "nine-tenths, if not ten-tenths, of the persons present were against the "Rocket"because of its appearance. " Nearly every person favoured some otherengine, so that there was nothing for the "Rocket" but the practicaltest. The first trip made by it was quite successful. It ran abouttwelve miles, without interruption, in about fifty-three minutes. 

The "Novelty" was next called out. It was a light engine, very compactin appearance, carrying the water and fuel upon the same wheels as theengine. The weight of the whole was only three tons and onehundred-weight. A peculiarity of this engine was that the air was drivenor _forced_ through the fire by means of bellows. The day being now faradvanced, and some dispute having arisen as to the method of assigningthe proper load for the "Novelty, " no particular experiment was madefurther than that the engine traversed the line by way of exhibition, occasionally moving at the rate of twenty-four miles an hour. The"Sanspareil, " constructed by Mr. Timothy Hackworth, was next exhibited, but no particular experiment was made with it on this day. This enginediffered but little in its construction from the locomotive lastsupplied by the Stephensons to the Stockton and Darlington Railway, ofwhich Mr. Hackworth was the locomotive foreman. 

The contest was postponed until the following day; but, before thejudges arrived on the ground, the bellows for creating the blast in the"Novelty" gave way, and it was found incapable of going through itsperformance. A defect was also detected in the boiler of the"Sanspareil, " and some further time was allowed to get it repaired. Thelarge number of spectators who had assembled to witness the contest weregreatly disappointed at this postponement; but, to lessen it, Stephensonagain brought out the "Rocket, " and, attaching it to a coach containingthirty persons, he ran them along the line at a rate of from twenty-fourto thirty miles an hour, much to their gratification and amazement. Before separating, the judges ordered the engine to be in readiness byeight o'clock on the following morning, to go through its definite trialaccording to the prescribed conditions. 

On the morning of the 8th of October the "Rocket" was again ready forthe contest. The engine was taken to the extremity of the stage, thefire-box was filled with coke, the fire lighted, and the steam raiseduntil it lifted the safety-valve loaded to a pressure of fifty pounds tothe square inch. This proceeding occupied fifty-seven minutes. Theengine then started on its journey, dragging after it about thirteentons' weight in waggons, and made the first ten trips backward andforward along two miles of road, running the thirty-five miles, including stoppages, in an hour and forty-eight minutes. The second tentrips were in like manner performed in two hours and three minutes. Themaximum velocity attained during the trial trip was twenty-nine miles anhour, or about three times the speed that one of the judges of thecompetition had declared to be the limit of possibility. The averagespeed at which the whole of the journeys was performed was fifteen milesan hour, or five miles beyond the rate specified in the conditionspublished by the company. The entire performance excited the greatestastonishment among the assembled spectators; the directors feltconfident that their enterprise was now on the eve of success; andGeorge Stephenson rejoiced to think that, in spite of all false prophetsand fickle counsellors, the locomotive system was now safe. When the"Rocket, " having performed all the conditions of the contest, arrived atthe "grand stand" at the close of its day's successful run, Mr. Cropper--one of the directors favourable to the fixed enginesystem--lifted up his hands, and exclaimed, "Now has George Stephensonat last delivered himself.... "

The "Rocket" had eclipsed the performance of all locomotive engines thathad yet been constructed, and outstripped even the sanguine expectationsof its constructors. It satisfactorily answered the report of Messrs. Walker and Rastrick, and established the efficiency of the locomotivefor working the Liverpool and Manchester Railway, and, indeed, allfuture railways. The "Rocket" showed that a new power had been born intothe world, full of activity and strength, with boundless capability ofwork. It was the simple but admirable contrivance of the steam-blast, and its combination with the multitubular boiler, that at once gavelocomotion a vigorous life, and secured the triumph of the railwaysystem. [8]

[Illustration: The "Rocket"]

FOOTNOTES:

[7] The conditions were these:

1. The engine must effectually consume its own smoke. 

2. The engine, if of six tons' weight, must be able to draw after it, day by day, twenty tons' weight (including the tender and water-tank) at_ten miles_ an hour, with a pressure of steam on the boiler notexceeding fifty pounds to the square inch. 

3. The boiler must have two safety-valves, neither of which must befastened down, and one of them be completely out of the control of theengine-man. 

4. The engine and boiler must be supported on springs, and rest on sixwheels, the height of the whole not exceeding fifteen feet to the top ofthe chimney. 

5. The engine, with water, must not weigh more than six tons; but anengine of less weight would be preferred on its drawing a proportionateload behind it; if of only four and a half tons, then it might be put ononly four wheels. The company will be at liberty to test the boiler, etc. , by a pressure of one hundred and fifty pounds to the square inch. 

6. A mercurial gauge must be affixed to the machine, showing the steampressure above forty-five pounds per square inch. 

7. The engine must be delivered, complete and ready for trial, at theLiverpool end of the railway, not later than the 1st of October, 1829. 

8. The price of the engine must not exceed £550. 

Many persons of influence declared the conditions published by thedirectors of the railway chimerical in the extreme. One gentleman ofsome eminence in Liverpool, Mr. P. Ewart, who afterward filled theoffice of Government Inspector of Post-office Steam Packets, declaredthat only a parcel of charlatans would ever have issued such a set ofconditions; that it had been _proved_ to be impossible to make alocomotive engine go at ten miles an hour; but if it ever was done, hewould undertake to eat a stewed engine-wheel for his breakfast. 

[8] When heavier and more powerful engines were brought upon the road, the old "Rocket, " becoming regarded as a thing of no value, was sold in1837. It has since been transferred to the Museum of Patents at SouthKensington, London, where it is still to be seen. 

Transcriber's Notes:

Page 30--imployed changed to employed. 

Page 31--subsequenty changed to subsequently. 

Page 47--build changed to building. 

Page 147--suggestor changed to suggester. 

Page 166--supgestion changed to suggestion. 

Footnote 7--Changed question mark for a period. 

Inconsistencies in hyphenated words have been made consistent. 

Obvious printer errors, including punctuation, have been correctedwithout note.