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THE ATOMIC BOMBINGS OF HIROSHIMA AND NAGASAKI

by The Manhattan Engineer District, June 29, 1946. 

Index

 FOREWORD INTRODUCTION THE MANHATTAN PROJECT INVESTIGATING GROUP PROPAGANDA SUMMARY OF DAMAGES AND INJURIES MAIN CONCLUSIONS THE SELECTION OF THE TARGET DESCRIPTION OF THE CITIES BEFORE THE BOMBINGS Hiroshima Nagasaki THE ATTACKS Hiroshima Nagasaki GENERAL COMPARISON OF HIROSHIMA AND NAGASAKI GENERAL DESCRIPTION OF DAMAGE CAUSED BY THE ATOMIC EXPLOSIONS TOTAL CASUALTIES THE NATURE OF AN ATOMIC EXPLOSION CHARACTERISTICS OF THE DAMAGE CAUSED BY THE ATOMIC BOMBS CALCULATIONS OF THE PEAK PRESSURE OF THE BLAST WAVE LONG RANGE BLAST DAMAGE GROUND SHOCK SHIELDING, OR SCREENING, FROM THE BLAST FLASH BURN CHARACTERISTICS OF INJURIES TO PERSONS BURNS MECHANICAL INJURIES BLAST INJURIES RADIATION INJURIES SHIELDING FROM RADIATION EFFECTS OF THE ATOMIC BOMBINGS ON THE INHABITANTS OF THE CITIES APPENDIX: Father Siemes' eyewitness account

FOREWORD

This report describes the effects of the atomic bombs which weredropped on the Japanese cities of Hiroshima and Nagasaki on August 6and 9, 1945, respectively. It summarizes all the authentic informationthat is available on damage to structures, injuries to personnel, morale effect, etc. , which can be released at this time withoutprejudicing the security of the United States. 

This report has been compiled by the Manhattan Engineer District of theUnited States Army under the direction of Major General Leslie R. Groves. Special acknowledgement to those whose work contributedlargely to this report is made to:

 The Special Manhattan Engineer District Investigating Group, The United States Strategic Bombing Survey, The British Mission to Japan, and

The Joint Atomic Bomb Investigating Group (Medical). And particularlyto the following individuals:

Col. Stafford L. Warren, Medical Corps, United States Army, for hisevaluation of medical data, Capt. Henry L. Barnett, Medical Corps, United States Army, for hisevaluation of medical data, Dr. R. Serber, for his comments on flash burn, Dr. Hans Bethe, Cornell University, for his information of the natureof atomic explosions, Majors Noland Varley and Walter C. Youngs, Corps of Engineers, UnitedStates Army, for their evaluation of physical damage to structures, J. 0. Hirschfelder, J. L. Magee, M. Hull, and S. T. Cohen, of the LosAlamos Laboratory, for their data on nuclear explosions, Lieut. Col. David B. Parker, Corps of Engineers, United States Army, for editing this report. 

INTRODUCTION

Statement by the President of the United States: "Sixteen hours ago anAmerican airplane dropped one bomb on Hiroshima, Japan, and destroyedits usefulness to the enemy. That bomb had more power than 20, 000 tonsof T. N. T. It had more than two thousand times the blast power of theBritish Grand Slam, which is the largest bomb ever yet used in thehistory of warfare". 

These fateful words of the President on August 6th, 1945, marked thefirst public announcement of the greatest scientific achievement inhistory. The atomic bomb, first tested in New Mexico on July 16, 1945, had just been used against a military target. 

On August 6th, 1945, at 8:15 A. M. , Japanese time, a B-29 heavy bomberflying at high altitude dropped the first atomic bomb on Hiroshima. More than 4 square miles of the city were instantly and completelydevastated. 66, 000 people were killed, and 69, 000 injured. 

On August 9th, three days later, at 11:02 A. M. , another B-29 droppedthe second bomb on the industrial section of the city of Nagasaki, totally destroying 1 1/2 square miles of the city, killing 39, 000persons, and injuring 25, 000 more. 

On August 10, the day after the atomic bombing of Nagasaki, theJapanese government requested that it be permitted to surrender underthe terms of the Potsdam declaration of July 26th which it hadpreviously ignored. 

THE MANHATTAN PROJECT ATOMIC BOMB INVESTIGATING GROUP

On August 11th, 1945, two days after the bombing of Nagasaki, a messagewas dispatched from Major General Leslie R. Groves to Brigadier GeneralThomas F. Farrell, who was his deputy in atomic bomb work and wasrepresenting him in operations in the Pacific, directing him toorganize a special Manhattan Project Atomic Bomb Investigating Group. 

This Group was to secure scientific, technical and medical intelligencein the atomic bomb field from within Japan as soon as possible afterthe cessation of hostilities. The mission was to consist of threegroups:

 1. Group for Hiroshima. 2. Group for Nagasaki. 3. Group to secure information concerning general Japanese activities in the field of atomic bombs. 

The first two groups were organized to accompany the first Americantroops into Hiroshima and Nagasaki. 

The primary purposes of the mission were as follows, in order ofimportance:

1. To make certain that no unusual hazards were present in the bombedcities. 

2. To secure all possible information concerning the effects of thebombs, both usual and unusual, and particularly with regard toradioactive effects, if any, on the targets or elsewhere. 

General Groves further stated that all available specialist personneland instruments would be sent from the United States, and that theSupreme Allied Commander in the Pacific would be informed about theorganization of the mission. 

On the same day, 11 August, the special personnel who formed the partof the investigating group to be sent from the United States wereselected and ordered to California with instructions to proceedoverseas at once to accomplish the purposes set forth in the message toGeneral Farrell. The main party departed from Hamilton Field, California on the morning of 13 August and arrived in the Marianas on15 August. 

On 12 August the Chief of Staff sent the Theater Commander thefollowing message:

"FOR MACARTHUR, SIGNED MARSHALL:

"GROVES HAS ORDERED FARRELL AT TINIAN TO ORGANIZE A SCIENTIFIC GROUP OFTHREE SECTIONS FOR POTENTIAL USE IN JAPAN IF SUCH USE SHOULD BEDESIRED. THE FIRST GROUP IS FOR HIROSHIMA, THE SECOND FOR NAGASAKI, AND THE THIRD FOR THE PURPOSE OF SECURING INFORMATION CONCERNINGGENERAL JAPANESE ACTIVITIES IN THE FIELD OF ATOMIC WEAPONS. THE GROUPSFOR HIROSHIMA AND NAGASAKI SHOULD ENTER THOSE CITIES WITH THE FIRSTAMERICAN TROOPS IN ORDER THAT THESE TROOPS SHALL NOT BE SUBJECTED TOANY POSSIBLE TOXIC EFFECTS ALTHOUGH WE HAVE NO REASON TO BELIEVE THATANY SUCH EFFECTS ACTUALLY EXIST. FARRELL AND HIS ORGANIZATION HAVE ALLAVAILABLE INFORMATION ON THIS SUBJECT. "

General Farrell arrived in Yokohama on 30 August, with the CommandingGeneral of the 8th Army; Colonel Warren, who was Chief of theRadiological Division of the District, arrived on 7 September. Themain body of the investigating group followed later. Preliminaryinspections of Hiroshima and Nagasaki were made on 8-9 and 13-14September, respectively. Members of the press had been enabled toprecede General Farrell to Hiroshima. 

The special groups spent 16 days in Nagasaki and 4 days in Hiroshima, during which time they collected as much information as was possibleunder their directives which called for a prompt report. After GeneralFarrell returned to the U. S. To make his preliminary report, the groupswere headed by Brigadier General J. B. Newman, Jr. More extensivesurveys have been made since that time by other agencies who had moretime and personnel available for the purpose, and much of theiradditional data has thrown further light on the effects of thebombings. This data has been duly considered in the making of thisreport. 

PROPAGANDA

On the day after the Hiroshima strike, General Farrell receivedinstructions from the War Department to engage in a propaganda campaignagainst the Japanese Empire in connection with the new weapon and itsuse against Hiroshima. The campaign was to include leaflets and anyother propaganda considered appropriate. With the fullest cooperationfrom CINCPAC of the Navy and the United States Strategic Air Forces, heinitiated promptly a campaign which included the preparation anddistribution of leaflets, broadcasting via short wave every 15 minutesover radio Saipan and the printing at Saipan and distribution over theEmpire of a Japanese language newspaper which included the descriptionand photographs of the Hiroshima strike. 

The campaign proposed:

1. Dropping 16, 000, 000 leaflets in a period of 9 days on 47 Japanesecities with population of over 100, 000. These cities represented morethan 40% of the total population. 

2. Broadcast of propaganda at regular intervals over radio Saipan. 

3. Distribution of 500, 000 Japanese language newspapers containingstories and pictures of the atomic bomb attacks. 

The campaign continued until the Japanese began their surrendernegotiations. At that time some 6, 000, 000 leaflets and a large numberof newspapers had been dropped. The radio broadcasts in Japanese hadbeen carried out at regular 15 minute intervals. 

SUMMARY OF DAMAGES AND INJURIES

Both the Hiroshima and the Nagasaki atomic bombs exhibited similareffects. 

The damages to man-made structures and other inanimate objects was theresult in both cities of the following effects of the explosions:

A. Blast, or pressure wave, similar to that of normal explosions. 

B. Primary fires, i. E. , those fires started instantaneously by theheat radiated from the atomic explosion. 

C. Secondary fires, i. E. , those fires resulting from the collapse ofbuildings, damage to electrical systems, overturning of stoves, andother primary effects of the blast. 

D. Spread of the original fires (B and C) to other structures. 

The casualties sustained by the inhabitants of both cities were due to:

A. "Flash" burns, caused directly by the almost instantaneousradiation of heat and light at the moment of the explosion. 

B. Burns resulting from the fires caused by the explosion. 

C. Mechanical injuries caused by collapse of buildings, flying debris, and forceable hurling--about of persons struck by the blast pressurewaves. 

D. Radiation injuries caused by the instantaneous penetratingradiation (in many respects similar to excessive X-ray exposure) fromthe nuclear explosion; all of these effective radiations occurredduring the first minute after initiation of the explosion, and nearlyall occurred during the first second of the explosion. 

No casualties were suffered as a result of any persistent radioactivityof fission products of the bomb, or any induced radioactivity ofobjects near the explosion. The gamma radiations emitted by thenuclear explosion did not, of course, inflict any damage on structures. 

The number of casualties which resulted from the pure blast effectalone (i. E. , because of simple pressure) was probably negligible incomparison to that caused by other effects. 

The central portions of the cities underneath the explosions sufferedalmost complete destruction. The only surviving objects were theframes of a small number of strong reinforced concrete buildings whichwere not collapsed by the blast; most of these buildings sufferedextensive damage from interior fires, had their windows, doors, andpartitions knocked out, and all other fixtures which were not integralparts of the reinforced concrete frames burned or blown away; thecasualties in such buildings near the center of explosion were almost100%. In Hiroshima fires sprang up simultaneously all over the wideflat central area of the city; these fires soon combined in an immense"fire storm" (high winds blowing inwards toward the center of a largeconflagration) similar to those caused by ordinary mass incendiaryraids; the resulting terrific conflagration burned out almosteverything which had not already been destroyed by the blast in aroughly circular area of 4. 4 square miles around the point directlyunder the explosion (this point will hereafter in this report bereferred to as X). Similar fires broke out in Nagasaki, but nodevastating fire storm resulted as in Hiroshima because of theirregular shape of the city. 

In both cities the blast totally destroyed everything within a radiusof 1 mile from the center of explosion, except for certain reinforcedconcrete frames as noted above. The atomic explosion almost completelydestroyed Hiroshima's identity as a city. Over a fourth of thepopulation was killed in one stroke and an additional fourth seriouslyinjured, so that even if there had been no damage to structures andinstallations the normal city life would still have been completelyshattered. Nearly everything was heavily damaged up to a radius of 3miles from the blast, and beyond this distance damage, althoughcomparatively light, extended for several more miles. Glass was brokenup to 12 miles. 

In Nagasaki, a smaller area of the city was actually destroyed than inHiroshima, because the hills which enclosed the target area restrictedthe spread of the great blast; but careful examination of the effectsof the explosion gave evidence of even greater blast effects than inHiroshima. Total destruction spread over an area of about 3 squaremiles. Over a third of the 50, 000 buildings in the target area ofNagasaki were destroyed or seriously damaged. The complete destructionof the huge steel works and the torpedo plant was especiallyimpressive. The steel frames of all buildings within a mile of theexplosion were pushed away, as by a giant hand, from the point ofdetonation. The badly burned area extended for 3 miles in length. Thehillsides up to a radius of 8, 000 feet were scorched, giving them anautumnal appearance. 

MAIN CONCLUSIONS

The following are the main conclusions which were reached afterthorough examination of the effects of the bombs dropped on Hiroshimaand Nagasaki:

1. No harmful amounts of persistent radioactivity were present afterthe explosions as determined by:

A. Measurements of the intensity of radioactivity at the time of theinvestigation; and

B. Failure to find any clinical evidence of persons harmed bypersistent radioactivity. 

The effects of the atomic bombs on human beings were of three maintypes:

A. Burns, remarkable for (1) the great ground area over which theywere inflicted and (2) the prevalence of "flash" burns caused by theinstantaneous heat radiation. 

B. Mechanical injuries, also remarkable for the wide area in whichsuffered. 

C. Effects resulting from penetrating gamma radiation. The effectsfrom radiation were due to instantaneous discharge of radiation at themoment of explosion and not to persistent radioactivity (of eitherfission products or other substances whose radioactivity might havebeen induced by proximity to the explosions). 

The effects of the atomic bombs on structures and installations were oftwo types:

A. Destruction caused by the great pressure from the blast; and

B. Destruction caused by the fires, either started directly by thegreat heat radiation, or indirectly through the collapse of buildings, wiring, etc. 

4. The actual tonnage of T. N. T. Which would have caused the same blastdamage was approximately of the order of 20, 000 tons. 

5. In respect to their height of burst, the bombs performed exactlyaccording to design. 

6. The bombs were placed in such positions that they could not havedone more damage from any alternative bursting point in either city. 

7. The heights of burst were correctly chosen having regard to thetype of destruction it was desired to cause. 

8. The information collected would enable a reasonably accurateprediction to be made of the blast damage likely to be caused in anycity where an atomic explosion could be effected. 

THE SELECTION OF THE TARGET

Some of the most frequent queries concerning the atomic bombs are thosedealing with the selection of the targets and the decision as to whenthe bombs would be used. 

The approximate date for the first use of the bomb was set in the fallof 1942 after the Army had taken over the direction of andresponsibility for the atomic bomb project. At that time, under thescientific assumptions which turned out to be correct, the summer of1945 was named as the most likely date when sufficient production wouldhave been achieved to make it possible actually to construct andutilize an atomic bomb. It was essential before this time to developthe technique of constructing and detonating the bomb and to make analmost infinite number of scientific and engineering developments andtests. Between the fall of 1942 and June 1945, the estimatedprobabilities of success had risen from about 60% to above 90%;however, not until July 16, 1945, when the first full-scale test tookplace in New Mexico, was it conclusively proven that the theories, calculations, and engineering were correct and that the bomb would besuccessful. 

The test in New Mexico was held 6 days after sufficient material hadbecome available for the first bomb. The Hiroshima bomb was readyawaiting suitable weather on July 31st, and the Nagasaki bomb was usedas soon after the Hiroshima bomb as it was practicable to operate thesecond mission. 

The work on the actual selection of targets for the atomic bomb wasbegun in the spring of 1945. This was done in close cooperation withthe Commanding General, Army Air Forces, and his Headquarters. Anumber of experts in various fields assisted in the study. Theseincluded mathematicians, theoretical physicists, experts on the blasteffects of bombs, weather consultants, and various other specialists. Some of the important considerations were:

A. The range of the aircraft which would carry the bomb. 

B. The desirability of visual bombing in order to insure the mosteffective use of the bomb. 

C. Probable weather conditions in the target areas. 

D. Importance of having one primary and two secondary targets for eachmission, so that if weather conditions prohibited bombing the targetthere would be at least two alternates. 

E. Selection of targets to produce the greatest military effect on theJapanese people and thereby most effectively shorten the war. 

F. The morale effect upon the enemy. 

These led in turn to the following:

A. Since the atomic bomb was expected to produce its greatest amountof damage by primary blast effect, and next greatest by fires, thetargets should contain a large percentage of closely-built framebuildings and other construction that would be most susceptible todamage by blast and fire. 

B. The maximum blast effect of the bomb was calculated to extend overan area of approximately 1 mile in radius; therefore the selectedtargets should contain a densely built-up area of at least this size. 

C. The selected targets should have a high military strategic value. 

D. The first target should be relatively untouched by previousbombing, in order that the effect of a single atomic bomb could bedetermined. 

The weather records showed that for five years there had never been twosuccessive good visual bombing days over Tokyo, indicating what mightbe expected over other targets in the home islands. The worst month ofthe year for visual bombing was believed to be June, after which theweather should improve slightly during July and August and then becomeworse again during September. Since good bombing conditions wouldoccur rarely, the most intense plans and preparations were necessary inorder to secure accurate weather forecasts and to arrange for fullutilization of whatever good weather might occur. It was also verydesirable to start the raids before September. 

DESCRIPTION OF THE CITIES BEFORE THE BOMBINGS

Hiroshima

The city of Hiroshima is located on the broad, flat delta of the OtaRiver, which has 7 channel outlets dividing the city into six islandswhich project into Hiroshima Bay. The city is almost entirely flat andonly slightly above sea level; to the northwest and northeast of thecity some hills rise to 700 feet. A single hill in the eastern part ofthe city proper about 1/2 mile long and 221 feet in height interruptedto some extent the spreading of the blast damage; otherwise the citywas fully exposed to the bomb. Of a city area of over 26 square miles, only 7 square miles were completely built-up. There was no markedseparation of commercial, industrial, and residential zones. 75% ofthe population was concentrated in the densely built-up area in thecenter of the city. 

Hiroshima was a city of considerable military importance. It containedthe 2nd Army Headquarters, which commanded the defense of all ofsouthern Japan. The city was a communications center, a storage point, and an assembly area for troops. To quote a Japanese report, "Probablymore than a thousand times since the beginning of the war did theHiroshima citizens see off with cries of 'Banzai' the troops leavingfrom the harbor. "

The center of the city contained a number of reinforced concretebuildings as well as lighter structures. Outside the center, the areawas congested by a dense collection of small wooden workshops set amongJapanese houses; a few larger industrial plants lay near the outskirtsof the city. The houses were of wooden construction with tile roofs. Many of the industrial buildings also were of wood frame construction. The city as a whole was highly susceptible to fire damage. 

Some of the reinforced concrete buildings were of a far strongerconstruction than is required by normal standards in America, becauseof the earthquake danger in Japan. This exceptionally strongconstruction undoubtedly accounted for the fact that the framework ofsome of the buildings which were fairly close to the center of damagein the city did not collapse. 

The population of Hiroshima had reached a peak of over 380, 000 earlierin the war but prior to the atomic bombing the population had steadilydecreased because of a systematic evacuation ordered by the Japanesegovernment. At the time of the attack the population was approximately255, 000. This figure is based on the registered population, used bythe Japanese in computing ration quantities, and the estimates ofadditional workers and troops who were brought into the city may not behighly accurate. Hiroshima thus had approximately the same number ofpeople as the city of Providence, R. I. , or Dallas, Tex. 

Nagasaki

Nagasaki lies at the head of a long bay which forms the best naturalharbor on the southern Japanese home island of Kyushu. The maincommercial and residential area of the city lies on a small plain nearthe end of the bay. Two rivers divided by a mountain spur form the twomain valleys in which the city lies. This mountain spur and theirregular lay-out of the city tremendously reduced the area ofdestruction, so that at first glance Nagasaki appeared to have beenless devastated than Hiroshima. 

The heavily build-up area of the city is confined by the terrain toless than 4 square miles out of a total of about 35 square miles in thecity as a whole. 

The city of Nagasaki had been one of the largest sea ports in southernJapan and was of great war-time importance because of its many andvaried industries, including the production of ordnance, ships, military equipment, and other war materials. The narrow long stripattacked was of particular importance because of its industries. 

In contrast to many modern aspects of Nagasaki, the residences almostwithout exception were of flimsy, typical Japanese construction, consisting of wood or wood-frame buildings, with wood walls with orwithout plaster, and tile roofs. Many of the smaller industries andbusiness establishments were also housed in wooden buildings orflimsily built masonry buildings. Nagasaki had been permitted to growfor many years without conforming to any definite city zoning plan andtherefore residences were constructed adjacent to factory buildings andto each other almost as close as it was possible to build themthroughout the entire industrial valley. 

THE ATTACKS

Hiroshima

Hiroshima was the primary target of the first atomic bomb mission. Themission went smoothly in every respect. The weather was good, and thecrew and equipment functioned perfectly. In every detail, the attackwas carried out exactly as planned, and the bomb performed exactly asexpected. 

The bomb exploded over Hiroshima at 8:15 on the morning of August 6, 1945. About an hour previously, the Japanese early warning radar nethad detected the approach of some American aircraft headed for thesouthern part of Japan. The alert had been given and radiobroadcasting stopped in many cities, among them Hiroshima. The planesapproached the coast at a very high altitude. At nearly 8:00 A. M. , theradar operator in Hiroshima determined that the number of planes comingin was very small--probably not more than three--and the air raid alertwas lifted. The normal radio broadcast warning was given to the peoplethat it might be advisable to go to shelter if B-29's were actuallysighted, but no raid was expected beyond some sort of reconnaissance. At 8:15 A. M. , the bomb exploded with a blinding flash in the sky, and agreat rush of air and a loud rumble of noise extended for many milesaround the city; the first blast was soon followed by the sounds offalling buildings and of growing fires, and a great cloud of dust andsmoke began to cast a pall of darkness over the city. 

At 8:16 A. M. , the Tokyo control operator of the Japanese BroadcastingCorporation noticed that the Hiroshima station had gone off the air. He tried to use another telephone line to reestablish his program, butit too had failed. About twenty minutes later the Tokyo railroadtelegraph center realized that the main line telegraph had stoppedworking just north of Hiroshima. From some small railway stops withinten miles of the city there came unofficial and confused reports of aterrible explosion in Hiroshima. All these reports were transmitted tothe Headquarters of the Japanese General Staff. 

Military headquarters repeatedly tried to call the Army Control Stationin Hiroshima. The complete silence from that city puzzled the men atHeadquarters; they knew that no large enemy raid could have occurred, and they knew that no sizeable store of explosives was in Hiroshima atthat time. A young officer of the Japanese General Staff wasinstructed to fly immediately to Hiroshima, to land, survey the damage, and return to Tokyo with reliable information for the staff. It wasgenerally felt at Headquarters that nothing serious had taken place, that it was all a terrible rumor starting from a few sparks of truth. 

The staff officer went to the airport and took off for the southwest. After flying for about three hours, while still nearly 100 miles fromHiroshima, he and his pilot saw a great cloud of smoke from the bomb. In the bright afternoon, the remains of Hiroshima were burning. 

Their plane soon reached the city, around which they circled indisbelief. A great scar on the land, still burning, and covered by aheavy cloud of smoke, was all that was left of a great city. Theylanded south of the city, and the staff officer immediately began toorganize relief measures, after reporting to Tokyo. 

Tokyo's first knowledge of what had really caused the disaster camefrom the White House public announcement in Washington sixteen hoursafter Hiroshima had been hit by the atomic bomb. 

Nagasaki

Nagasaki had never been subjected to large scale bombing prior to theexplosion of the atomic bomb there. On August 1st, 1945, however, anumber of high explosive bombs were dropped on the city. A few ofthese bombs hit in the shipyards and dock areas in the southwestportion of the city. Several of the bombs hit the Mitsubishi Steel andArms Works and six bombs landed at the Nagasaki Medical School andHospital, with three direct hits on buildings there. While the damagefrom these few bombs were relatively small, it created considerableconcern in Nagasaki and a number of people, principally schoolchildren, were evacuated to rural areas for safety, thus reducing thepopulation in the city at the time of the atomic attack. 

On the morning of August 9th, 1945, at about 7:50 A. M. , Japanese time, an air raid alert was sounded in Nagasaki, but the "All clear" signalwas given at 8:30. When only two B-29 superfortresses were sighted at10:53 the Japanese apparently assumed that the planes were only onreconnaissance and no further alarm was given. A few moments later, at11:00 o'clock, the observation B-29 dropped instruments attached tothree parachutes and at 11:02 the other plane released the atomic bomb. 

The bomb exploded high over the industrial valley of Nagasaki, almostmidway between the Mitsubishi Steel and Arms Works, in the south, andthe Mitsubishi-Urakami Ordnance Works (Torpedo Works), in the north, the two principal targets of the city. 

Despite its extreme importance, the first bombing mission on Hiroshimahad been almost routine. The second mission was not so uneventful. Again the crew was specially trained and selected; but bad weatherintroduced some momentous complications. These complications are bestdescribed in the brief account of the mission's weaponeer, Comdr. , nowCapt. , F. L. Ashworth, U. S. N. , who was in technical command of thebomb and was charged with the responsibility of insuring that the bombwas successfully dropped at the proper time and on the designatedtarget. His narrative runs as follows:

"The night of our take-off was one of tropical rain squalls, andflashes of lightning stabbed into the darkness with disconcertingregularity. The weather forecast told us of storms all the way fromthe Marianas to the Empire. Our rendezvous was to be off the southeastcoast of Kyushu, some 1500 miles away. There we were to join with ourtwo companion observation B-29's that took off a few minutes behind us. Skillful piloting and expert navigation brought us to the rendezvouswithout incident. 

"About five minutes after our arrival, we were joined by the first ofour B-29's. The second, however, failed to arrive, having apparentlybeen thrown off its course by storms during the night. We waited 30minutes and then proceeded without the second plane toward the targetarea. 

"During the approach to the target the special instruments installed inthe plane told us that the bomb was ready to function. We wereprepared to drop the second atomic bomb on Japan. But fate was againstus, for the target was completely obscured by smoke and haze. Threetimes we attempted bombing runs, but without success. Then withanti-aircraft fire bursting around us and with a number of enemyfighters coming up after us, we headed for our secondary target, Nagasaki. 

"The bomb burst with a blinding flash and a huge column of black smokeswirled up toward us. Out of this column of smoke there boiled a greatswirling mushroom of gray smoke, luminous with red, flashing flame, that reached to 40, 000 feet in less than 8 minutes. Below through theclouds we could see the pall of black smoke ringed with fire thatcovered what had been the industrial area of Nagasaki. 

"By this time our fuel supply was dangerously low, so after one quickcircle of Nagasaki, we headed direct for Okinawa for an emergencylanding and refueling". 

GENERAL COMPARISON OF HIROSHIMA AND NAGASAKI

It was not at first apparent to even trained observers visiting the twoJapanese cities which of the two bombs had been the most effective. 

In some respects, Hiroshima looked worse than Nagasaki. The firedamage in Hiroshima was much more complete; the center of the city washit and everything but the reinforced concrete buildings had virtuallydisappeared. A desert of clear-swept, charred remains, with only a fewstrong building frames left standing was a terrifying sight. 

At Nagasaki there were no buildings just underneath the center ofexplosion. The damage to the Mitsubishi Arms Works and the TorpedoWorks was spectacular, but not overwhelming. There was something leftto see, and the main contours of some of the buildings were stillnormal. 

An observer could stand in the center of Hiroshima and get a view ofthe most of the city; the hills prevented a similar overall view inNagasaki. Hiroshima impressed itself on one's mind as a vast expanseof desolation; but nothing as vivid was left in one's memory ofNagasaki. 

When the observers began to note details, however, striking differencesappeared. Trees were down in both cities, but the large trees whichfell in Hiroshima were uprooted, while those in Nagasaki were actuallysnapped off. A few reinforced concrete buildings were smashed at thecenter in Hiroshima, but in Nagasaki equally heavy damage could befound 2, 300 feet from X. In the study of objects which gave definiteclues to the blast pressure, such as squashed tin cans, dished metalplates, bent or snapped poles and like, it was soon evident that theNagasaki bomb had been much more effective than the Hiroshima bomb. Inthe description of damage which follows, it will be noted that theradius for the amount of damage was greater in Nagasaki than Hiroshima. 

GENERAL DESCRIPTION OF DAMAGE CAUSED BY THE ATOMIC EXPLOSIONS

In considering the devastation in the two cities, it should beremembered that the cities' differences in shape and topographyresulted in great differences in the damages. Hiroshima was all onlow, flat ground, and was roughly circular in shape; Nagasaki was muchcut up by hills and mountain spurs, with no regularity to its shape. 

In Hiroshima almost everything up to about one mile from X wascompletely destroyed, except for a small number (about 50) of heavilyreinforced concrete buildings, most of which were specially designed towithstand earthquake shock, which were not collapsed by the blast; mostof these buildings had their interiors completely gutted, and allwindows, doors, sashes, and frames ripped out. In Nagasaki, nearlyeverything within 1/2 mile of the explosion was destroyed, includingheavy structures. All Japanese homes were destroyed within 1 1/2 milesfrom X. 

Underground air raid shelters with earth cover roofs immediately belowthe explosion had their roofs caved in; but beyond 1/2 mile from X theysuffered no damage. 

In Nagasaki, 1500 feet from X high quality steel frame buildings werenot completely collapsed, but the entire buildings suffered massdistortion and all panels and roofs were blown in. 

In Nagasaki, 2, 000 feet from X, reinforced concrete buildings with 10"walls and 6" floors were collapsed; reinforced concrete buildings with4" walls and roofs were standing but were badly damaged. At 2, 000 feetsome 9" concrete walls were completely destroyed. 

In Nagasaki, 3, 500 feet from X, church buildings with 18" brick wallswere completely destroyed. 12" brick walls were severely cracked asfar as 5, 000 feet. 

In Hiroshima, 4, 400 feet from X, multi-story brick buildings werecompletely demolished. In Nagasaki, similar buildings were destroyedto 5, 300 feet. 

In Hiroshima, roof tiles were bubbled (melted) by the flash heat out to4, 000 feet from X; in Nagasaki, the same effect was observed to 6, 500feet. 

In Hiroshima, steel frame buildings were destroyed 4, 200 feet from X, and to 4, 800 feet in Nagasaki. 

In both cities, the mass distortion of large steel buildings wasobserved out to 4, 500 feet from X. 

In Nagasaki, reinforced concrete smoke stacks with 8" walls, speciallydesigned to withstand earthquake shocks, were overturned up to 4, 000feet from X. 

In Hiroshima, steel frame buildings suffered severe structural damageup to 5, 700 feet from X, and in Nagasaki the same damage was sustainedas far as 6, 000 feet. 

In Nagasaki, 9" brick walls were heavily cracked to 5, 000 feet, weremoderately cracked to 6, 000 feet, and slightly cracked to 8, 000 feet. In both cities, light concrete buildings collapsed out to 4, 700 feet. 

In Hiroshima, multi-story brick buildings suffered structural damage upto 6, 600 feet, and in Nagasaki up to 6, 500 feet from X. 

In both cities overhead electric installations were destroyed up to5, 500 feet; and trolley cars were destroyed up to 5, 500 feet, anddamaged to 10, 500 feet. 

Flash ignition of dry, combustible material was observed as far as6, 400 feet from X in Hiroshima, and in Nagasaki as far as 10, 000 feetfrom X. 

Severe damage to gas holders occured out to 6, 500 feet in both cities. 

All Japanese homes were seriously damaged up to 6, 500 feet inHiroshima, and to 8, 000 feet in Nagasaki. Most Japanese homes weredamaged up to 8, 000 feet in Hiroshima and 10, 500 feet in Nagasaki. 

The hillsides in Nagasaki were scorched by the flash radiation of heatas far as 8, 000 feet from X; this scorching gave the hillsides theappearance of premature autumn. 

In Nagasaki, very heavy plaster damage was observed in many buildingsup to 9, 000 feet; moderate damage was sustained as far as 12, 000 feet, and light damage up to 15, 000 feet. 

The flash charring of wooden telegraph poles was observed up to 9, 500feet from X in Hiroshima, and to 11, 000 feet in Nagasaki; some reportsindicate flash burns as far as 13, 000 feet from X in both places. 

Severe displacement of roof tiles was observed up to 8, 000 feet inHiroshima, and to 10, 000 feet in Nagasaki. 

In Nagasaki, very heavy damage to window frames and doors was observedup to 8, 000 feet, and light damage up to 12, 000 feet. 

Roofs and wall coverings on steel frame buildings were destroyed out to11, 000 feet. 

Although the sources of many fires were difficult to trace accurately, it is believed that fires were started by primary heat radiation as faras 15, 000 feet from X. 

Roof damage extended as far as 16, 000 feet from X in Hiroshima and inNagasaki. 

The actual collapse of buildings was observed at the extreme range of23, 000 feet from X in Nagasaki. 

Although complete window damage was observed only up to 12, 000 feetfrom X, some window damage occurred in Nagasaki up to 40, 000 feet, andactual breakage of glass occured up to 60, 000 feet. 

Heavy fire damage was sustained in a circular area in Hiroshima with amean radius of about 6, 000 feet and a maximum radius of about 11, 000feet; similar heavy damage occured in Nagasaki south of X up to 10, 000feet, where it was stopped on a river course. 

In Hiroshima over 60, 000 of 90, 000 buildings were destroyed or severelydamaged by the atomic bomb; this figure represents over 67% of thecity's structures. 

In Nagasaki 14, 000 or 27% of 52, 000 residences were completelydestroyed and 5, 400, or 10% were half destroyed. Only 12% remainedundamaged. This destruction was limited by the layout of the city. The following is a summary of the damage to buildings in Nagasaki asdetermined from a ground survey made by the Japanese:

 Destruction of Buildings and Houses Number Percentage (Compiled by Nagasaki Municipality)

 Total in Nagasaki (before atomic explosion) 50, 000 100. 0 Blasted (not burned) 2, 652 5. 3 Blasted and burned 11, 494 23. 0 Blasted and/or burned 14, 146 28. 3 Partially burned or blasted 5, 441 10. 9 Total buildings and houses destroyed 19, 587 39. 2 Undamaged 30, 413 60. 8

In Hiroshima, all utilities and transportation services were disruptedfor varying lengths of time. In general however services were restoredabout as rapidly as they could be used by the depleted population. Through railroad service was in order in Hiroshima on 8 August, andelectric power was available in most of the surviving parts on 7August, the day after the bombing. The reservoir of the city was notdamaged, being nearly 2 miles from X. However, 70, 000 breaks in waterpipes in buildings and dwellings were caused by the blast and fireeffects. Rolling transportation suffered extensive damage. The damageto railroad tracks, and roads was comparatively small, however. Theelectric power transmission and distribution systems were badlywrecked. The telephone system was approximately 80% damaged, and noservice was restored until 15 August. 

Despite the customary Japanese lack of attention to sanitationmeasures, no major epidemic broke out in the bombed cities. Althoughthe conditions following the bombings makes this fact seem surprising, the experience of other bombed cities in both Germany and Japan showHiroshima and Nagasaki not to be isolated cases. 

The atomic explosion over Nagasaki affected an over-all area ofapproximately 42. 9 square miles of which about 8. 5 square miles werewater and only about 9. 8 square miles were built up, the remainderbeing partially settled. Approximately 36% of the built up areas wereseriously damaged. The area most severely damaged had an averageradius of about 1 mile, and covered about 2. 9 square miles of which 2. 4were built up. 

In Nagasaki, buildings with structural steel frames, principally theMitsubishi Plant as far as 6, 000 feet from X were severely damaged;these buildings were typical of wartime mill construction in Americaand Great Britain, except that some of the frames were somewhat lesssubstantial. The damage consisted of windows broken out (100%), steelsashes ripped out or bent, corrugated metal or corrugated asbestosroofs and sidings ripped off, roofs bent or destroyed, roof trussescollapsed, columns bent and cracked and concrete foundations forcolumns rotated. Damage to buildings with structural steel frames wasmore severe where the buildings received the effect of the blast ontheir sides than where the blast hit the ends of buildings, because thebuildings had more stiffness (resistance to negative moment at the topof columns) in a longitudinal direction. Many of the lightlyconstructed steel frame buildings collapsed completely while some ofthe heavily constructed (to carry the weight of heavy cranes and loads)were stripped of roof and siding, but the frames were only partiallyinjured. 

The next most seriously damaged area in Nagasaki lies outside the 2. 9square miles just described, and embraces approximately 4. 2 squaremiles of which 29% was built up. The damage from blast and fire wasmoderate here, but in some sections (portions of main businessdistricts) many secondary fires started and spread rapidly, resultingin about as much over-all destruction as in areas much closer to X. 

An area of partial damage by blast and fire lies just outside the onejust described and comprises approximately 35. 8 square miles. Of thisarea, roughly 1/6th was built up and 1/4th was water. The extent ofdamage varied from serious (severe damage to roofs and windows in themain business section of Nagasaki, 2. 5 miles from X), to minor (brokenor occasionally broken windows at a distance of 7 miles southeast of X). 

As intended, the bomb was exploded at an almost ideal location overNagasaki to do the maximum damage to industry, including the MitsubishiSteel and Arms Works, the Mitsubishi-Urakami Ordnance Works (TorpedoWorks), and numerous factories, factory training schools, and otherindustrial establishments, with a minimum destruction of dwellings andconsequently, a minimum amount of casualties. Had the bomb beendropped farther south, the Mitsubishi-Urakami Ordnance Works would nothave been so severely damaged, but the main business and residentialdistricts of Nagasaki would have sustained much greater damagecasualties. 

Calculations show that the structural steel and reinforced concreteframes which survived the blast fairly close to X could not havewithstood the estimated peak pressures developed against the totalareas presented by the sides and roof of the buildings. The survivalof these frames is explained by the fact that they were not actuallyrequired to withstand the peak pressure because the windows werequickly knocked out and roof and siding stripped off thereby reducingtotal area and relieving the pressure. While this saved the buildingframe, it permitted severe damage to building interior and contents, and injuries to the building occupants. Buildings without large panelopenings through which the pressure could dissipate were completelycrushed, even when their frames were as strong as those which survived. 

The damage sustained by reinforced concrete buildings depended both onthe proximity to X and the type and strength of the reinforced concreteconstruction. Some of the buildings with reinforced concrete framesalso had reinforced concrete walls, ceilings, and partitions, whileothers had brick or concrete tile walls covered either with plaster orornamental stone, with partitions of metal, glass, and plaster. Withthe exception of the Nagasaki Medical School and Hospital group, whichwas designed to withstand earthquakes and was therefore of heavierconstruction than most American structures, most of the reinforcedconcrete structures could be classified only as fair, with concrete oflow strength and density, with many of the columns, beams, and slabsunderdesigned and improperly reinforced. These facts account for someof the structural failures which occured. 

In general, the atomic bomb explosion damaged all windows and rippedout, bent, or twisted most of the steel window or door sashes, rippeddoors from hinges, damaged all suspended wood, metal, and plasterceilings. The blast concussion also caused great damage to equipmentby tumbling and battering. Fires generally of secondary originconsumed practically all combustible material, caused plaster to crackoff, burned all wooden trim, stair covering, wooden frames of woodensuspended ceilings, beds, mattresses, and mats, and fused glass, ruinedall equipment not already destroyed by the blast, ruined all electricalwiring, plumbing, and caused spalling of concrete columns and beams inmany of the rooms. 

Almost without exception masonry buildings of either brick or stonewithin the effective limits of the blast were severely damaged so thatmost of them were flattened or reduced to rubble. The wreckage of achurch, approximately 1, 800 feet east of X in Nagasaki, was one of thefew masonry buildings still recognizable and only portions of the wallsof this structure were left standing. These walls were extremely thick(about 2 feet). The two domes of the church had reinforced concreteframes and although they were toppled, they held together as units. 

Practically every wooden building or building with timber frame within2. 0 miles of X was either completely destroyed or very seriouslydamaged, and significant damage in Nagasaki resulted as far as 3 milesfrom X. Nearly all such buildings collapsed and a very large numberwere consumed by fire. 

A reference to the various photographs depicting damage shows thatalthough most of the buildings within the effective limits of the blastwere totally destroyed or severely damaged, a large number of chimneyseven close to X were left standing, apparently uninjured by theconcussion. One explanation is that concrete chimneys areapproximately cylindrical in shape and consequently offer much lesswind resistance than flat surfaces such as buildings. Anotherexplanation is that since the cities were subject to typhoons the moremodern chimneys were probably designed to withstand winds of highvelocity. It is also probable that most of the recently constructedchimneys as well as the more modern buildings were constructed towithstand the acceleration of rather severe earthquakes. Since thebombs were exploded high in the air, chimneys relatively close to Xwere subjected to more of a downward than a lateral pressure, andconsequently the overturning moment was much less than might have beenanticipated. 

Although the blast damaged many bridges to some extent, bridge damagewas on the whole slight in comparison to that suffered by buildings. The damage varied from only damaged railings to complete destruction ofthe superstructure. Some of the bridges were wrecked and the spanswere shoved off their piers and into the river bed below by the forceof the blast. Others, particularly steel plate girder bridges, werebadly buckled by the blast pressure. None of the failures observedcould be attributed to inadequate design or structural weaknesses. 

The roads, and railroad and street railway trackage sustainedpractically no primary damage as a result of the explosion. Most ofthe damage to railroads occurred from secondary causes, such as firesand damage to bridges or other structures. Rolling stock, as well asautomobiles, trolleys, and buses were destroyed and burned up to aconsiderable distance from X. Streets were impassable for awhilebecause of the debris, but they were not damaged. The height of thebomb explosion probably explains the absence of direct damage torailroads and roads. 

A large part of the electric supply was interrupted by the bomb blastchiefly through damage to electric substations and overheadtransmission systems. Both gas works in Nagasaki were severely damagedby the bomb. These works would have required 6-7 months to get intooperation. In addition to the damage sustained by the electrical andgas systems, severe damage to the water supply system was reported bythe Japanese government; the chief damage was a number of breaks in thelarge water mains and in almost all of the distributing pipes in theareas which were affected by the blast. Nagasaki was still sufferingfrom a water shortage inside the city six weeks after the atomic attack. 

The Nagasaki Prefectural report describes vividly the effects of thebomb on the city and its inhabitants:

"Within a radius of 1 kilometer from X, men and animals died almostinstantaneously and outside a radius of 1 kilometer and within a radiusof 2 kilometers from X, some men and animals died instantly from thegreat blast and heat but the great majority were seriously orsuperficially injured. Houses and other structures were completelydestroyed while fires broke out everywhere. Trees were uprooted andwithered by the heat. 

"Outside a radius of 2 kilometers and within a radius of 4 kilometersfrom X, men and animals suffered various degrees of injury from windowglass and other fragments scattered about by the blast and many wereburned by the intense heat. Dwellings and other structures were halfdamaged by blast. 

"Outside a radius of 4 kilometers and within a radius of 8 kilometersliving creatures were injured by materials blown about by the blast;the majority were only superficially wounded. Houses were only half orpartially damaged. "

The British Mission to Japan interpreted their observations of thedestruction of buildings to apply to similar construction of their ownas follows:

A similar bomb exploding in a similar fashion would produce thefollowing effects on normal British houses:

Up to 1, 000 yards from X it would cause complete collapse. 

Up to 1 mile from X it would damage the houses beyond repair. 

Up to 1. 5 miles from X it would render them uninhabitable withoutextensive repair, particularly to roof timbers. 

Up to 2. 5 miles from X it would render them uninhabitable untilfirst-aid repairs had been carried out. 

The fire damage in both cities was tremendous, but was more complete inHiroshima than in Nagasaki. The effect of the fires was to changeprofoundly the appearance of the city and to leave the central partbare, except for some reinforced concrete and steel frames and objectssuch as safes, chimney stacks, and pieces of twisted sheet metal. Thefire damage resulted more from the properties of the cities themselvesthan from those of the bombs. 

The conflagration in Hiroshima caused high winds to spring up as airwas drawn in toward the center of the burning area, creating a "firestorm". The wind velocity in the city had been less than 5 miles perhour before the bombing, but the fire-wind attained a velocity of 30-40miles per hour. These great winds restricted the perimeter of the firebut greatly added to the damage of the conflagration within theperimeter and caused the deaths of many persons who might otherwisehave escaped. In Nagasaki, very severe damage was caused by fires, butno extensive "fire storm" engulfed the city. In both cities, some ofthe fires close to X were no doubt started by the ignition of highlycombustible material such as paper, straw, and dry cloth, upon theinstantaneous radiation of heat from the nuclear explosion. Thepresence of large amounts of unburnt combustible materials near X, however, indicated that even though the heat of the blast was veryintense, its duration was insufficient to raise the temperature of manymaterials to the kindling point except in cases where conditions wereideal. The majority of the fires were of secondary origin startingfrom the usual electrical short-circuits, broken gas lines, overturnedstoves, open fires, charcoal braziers, lamps, etc. , following collapseor serious damage from the direct blast. 

Fire fighting and rescue units were stripped of men and equipment. Almost 30 hours elapsed before any rescue parties were observable. InHiroshima only a handful of fire engines were available for fightingthe ensuing fires, and none of these were of first class type. In anycase, however, it is not likely that any fire fighting equipment orpersonnel or organization could have effected any significant reductionin the amount of damage caused by the tremendous conflagration. 

A study of numerous aerial photographs made prior to the atomicbombings indicates that between 10 June and 9 August 1945 the Japaneseconstructed fire breaks in certain areas of the cities in order tocontrol large scale fires. In general these fire breaks were noteffective because fires were started at so many locationssimultaneously. They appear, however, to have helped prevent firesfrom spreading farther east into the main business and residentialsection of Nagasaki. 

TOTAL CASUALTIES

There has been great difficulty in estimating the total casualties inthe Japanese cities as a result of the atomic bombing. The extensivedestruction of civil installations (hospitals, fire and policedepartment, and government agencies) the state of utter confusionimmediately following the explosion, as well as the uncertaintyregarding the actual population before the bombing, contribute to thedifficulty of making estimates of casualties. The Japanese periodiccensuses are not complete. Finally, the great fires that raged in eachcity totally consumed many bodies. 

The number of total casualties has been estimated at various timessince the bombings with wide discrepancies. The Manhattan EngineerDistrict's best available figures are:

 TABLE A Estimates of Casualties

 Hiroshima Nagasaki Pre-raid population 255, 000 195, 000 Dead 66, 000 39, 000 Injured 69, 000 25, 000 Total Casualties 135, 000 64, 000

The relation of total casualties to distance from X, the center ofdamage and point directly under the air-burst explosion of the bomb, isof great importance in evaluating the casualty-producing effect of thebombs. This relationship for the total population of Nagasaki is shownin the table below, based on the first-obtained casualty figures of theDistrict:

 TABLE B Relation of Total Casualties to Distance from X

 Distance Total Killed per from X, feet Killed Injured Missing Casualties square mile 0 - 1, 640 7, 505 960 1, 127 9, 592 24, 700 1, 640 - 3, 300 3, 688 1, 478 1, 799 6, 965 4, 040 3, 300 - 4, 900 8, 678 17, 137 3, 597 29, 412 5, 710 4, 900 - 6, 550 221 11, 958 28 12, 207 125 6, 550 - 9, 850 112 9, 460 17 9, 589 20

No figure for total pre-raid population at these different distanceswere available. Such figures would be necessary in order to computeper cent mortality. A calculation made by the British Mission to Japanand based on a preliminary analysis of the study of the JointMedical-Atomic Bomb Investigating Commission gives the followingcalculated values for per cent mortality at increasing distances from X:

 TABLE C Per-Cent Mortality at Various Distances

 Distance from X, Per-cent Mortality in feet 0 - 1000 93. 0% 1000 - 2000 92. 0 2000 - 3000 86. 0 3000 - 4000 69. 0 4000 - 5000 49. 0 5000 - 6000 31. 5 6000 - 7000 12. 5 7000 - 8000 1. 3 8000 - 9000 0. 5 9000 - 10, 000 0. 0

It seems almost certain from the various reports that the greatesttotal number of deaths were those occurring immediately after thebombing. The causes of many of the deaths can only be surmised, and ofcourse many persons near the center of explosion suffered fatalinjuries from more than one of the bomb effects. The proper order ofimportance for possible causes of death is: burns, mechanical injury, and gamma radiation. Early estimates by the Japanese are shown in Dbelow:

 TABLE D Cause of Immediate Deaths

 City Cause of Death Per-cent of Total Hiroshima Burns 60% Falling debris 30 Other 10

 Nagasaki Burns 95% Falling debris 9 Flying glass 7 Other 7

THE NATURE OF AN ATOMIC EXPLOSION

The most striking difference between the explosion of an atomic bomband that of an ordinary T. N. T. Bomb is of course in magnitude; as thePresident announced after the Hiroshima attack, the explosive energy ofeach of the atomic bombs was equivalent to about 20, 000 tons of T. N. T. 

But in addition to its vastly greater power, an atomic explosion hasseveral other very special characteristics. Ordinary explosion is achemical reaction in which energy is released by the rearrangement ofthe atoms of the explosive material. In an atomic explosion theidentity of the atoms, not simply their arrangement, is changed. Aconsiderable fraction of the mass of the explosive charge, which may beuranium 235 or plutonium, is transformed into energy. Einstein'sequation, E = mc^2, shows that matter that is transformed into energymay yield a total energy equivalent to the mass multiplied by thesquare of the velocity of light. The significance of the equation iseasily seen when one recalls that the velocity of light is 186, 000miles per second. The energy released when a pound of T. N. T. Explodeswould, if converted entirely into heat, raise the temperature of 36lbs. Of water from freezing temperature (32 deg F) to boilingtemperature (212 deg F). The nuclear fission of a pound of uraniumwould produce an equal temperature rise in over 200 million pounds ofwater. 

The explosive effect of an ordinary material such as T. N. T. Is derivedfrom the rapid conversion of solid T. N. T. To gas, which occupiesinitially the same volume as the solid; it exerts intense pressures onthe surrounding air and expands rapidly to a volume many times largerthan the initial volume. A wave of high pressure thus rapidly movesoutward from the center of the explosion and is the major cause ofdamage from ordinary high explosives. An atomic bomb also generates awave of high pressure which is in fact of, much higher pressure thanthat from ordinary explosions; and this wave is again the major causeof damage to buildings and other structures. It differs from thepressure wave of a block buster in the size of the area over which highpressures are generated. It also differs in the duration of thepressure pulse at any given point: the pressure from a blockbusterlasts for a few milliseconds (a millisecond is one thousandth of asecond) only, that from the atomic bomb for nearly a second, and wasfelt by observers both in Japan and in New Mexico as a very strong windgoing by. 

The next greatest difference between the atomic bomb and the T. N. T. Explosion is the fact that the atomic bomb gives off greater amounts ofradiation. Most of this radiation is "light" of some wave-lengthranging from the so-called heat radiations of very long wave length tothe so-called gamma rays which have wave-lengths even shorter than theX-rays used in medicine. All of these radiations travel at the samespeed; this, the speed of light, is 186, 000 miles per second. Theradiations are intense enough to kill people within an appreciabledistance from the explosion, and are in fact the major cause of deathsand injuries apart from mechanical injuries. The greatest number ofradiation injuries was probably due to the ultra-violet rays which havea wave length slightly shorter than visible light and which causedflash burn comparable to severe sunburn. After these, the gamma raysof ultra short wave length are most important; these cause injuriessimilar to those from over-doses of X-rays. 

The origin of the gamma rays is different from that of the bulk of theradiation: the latter is caused by the extremely high temperatures inthe bomb, in the same way as light is emitted from the hot surface ofthe sun or from the wires in an incandescent lamp. The gamma rays onthe other hand are emitted by the atomic nuclei themselves when theyare transformed in the fission process. The gamma rays are thereforespecific to the atomic bomb and are completely absent in T. N. T. Explosions. The light of longer wave length (visible and ultra-violet)is also emitted by a T. N. T. Explosion, but with much smaller intensitythan by an atomic bomb, which makes it insignificant as far as damageis concerned. 

A large fraction of the gamma rays is emitted in the first fewmicroseconds (millionths of a second) of the atomic explosion, togetherwith neutrons which are also produced in the nuclear fission. Theneutrons have much less damage effect than the gamma rays because theyhave a smaller intensity and also because they are strongly absorbed inair and therefore can penetrate only to relatively small distances fromthe explosion: at a thousand yards the neutron intensity is negligible. After the nuclear emission, strong gamma radiation continues to comefrom the exploded bomb. This generates from the fission products andcontinues for about one minute until all of the explosion products haverisen to such a height that the intensity received on the ground isnegligible. A large number of beta rays are also emitted during thistime, but they are unimportant because their range is not very great, only a few feet. The range of alpha particles from the unused activematerial and fissionable material of the bomb is even smaller. 

Apart from the gamma radiation ordinary light is emitted, some of whichis visible and some of which is the ultra violet rays mainlyresponsible for flash burns. The emission of light starts a fewmilliseconds after the nuclear explosion when the energy from theexplosion reaches the air surrounding the bomb. The observer sees thena ball of fire which rapidly grows in size. During most of the earlytime, the ball of fire extends as far as the wave of high pressure. Asthe ball of fire grows its temperature and brightness decrease. Several milliseconds after the initiation of the explosion, thebrightness of the ball of fire goes through a minimum, then it getssomewhat brighter and remains at the order of a few times thebrightness of the sun for a period of 10 to 15 seconds for an observerat six miles distance. Most of the radiation is given off after thispoint of maximum brightness. Also after this maximum, the pressurewaves run ahead of the ball of fire. 

The ball of fire rapidly expands from the size of the bomb to a radiusof several hundred feet at one second after the explosion. After thisthe most striking feature is the rise of the ball of fire at the rateof about 30 yards per second. Meanwhile it also continues to expand bymixing with the cooler air surrounding it. At the end of the firstminute the ball has expanded to a radius of several hundred yards andrisen to a height of about one mile. The shock wave has by now reacheda radius of 15 miles and its pressure dropped to less than 1/10 of apound per square inch. The ball now loses its brilliance and appearsas a great cloud of smoke: the pulverized material of the bomb. Thiscloud continues to rise vertically and finally mushrooms out at analtitude of about 25, 000 feet depending upon meteorological conditions. The cloud reaches a maximum height of between 50, 000 and 70, 000 feet ina time of over 30 minutes. 

It is of interest to note that Dr. Hans Bethe, then a member of theManhattan Engineer District on loan from Cornell University, predictedthe existence and characteristics of this ball of fire months beforethe first test was carried out. 

To summarize, radiation comes in two bursts--an extremely intense onelasting only about 3 milliseconds and a less intense one of much longerduration lasting several seconds. The second burst contains by far thelarger fraction of the total light energy, more than 90%. But thefirst flash is especially large in ultra-violet radiation which isbiologically more effective. Moreover, because the heat in this flashcomes in such a short time, there is no time for any cooling to takeplace, and the temperature of a person's skin can be raised 50 degreescentigrade by the flash of visible and ultra-violet rays in the firstmillisecond at a distance of 4, 000 yards. People may be injured byflash burns at even larger distances. Gamma radiation danger does notextend nearly so far and neutron radiation danger is still more limited. 

The high skin temperatures result from the first flash of highintensity radiation and are probably as significant for injuries as thetotal dosages which come mainly from the second more sustained burst ofradiation. The combination of skin temperature increase plus largeultra-violet flux inside 4, 000 yards is injurious in all cases toexposed personnel. Beyond this point there may be cases of injury, depending upon the individual sensitivity. The infra-red dosage isprobably less important because of its smaller intensity. 

CHARACTERISTICS OF THE DAMAGE CAUSED BY THE ATOMIC BOMBS

The damage to man-made structures caused by the bombs was due to twodistinct causes: first the blast, or pressure wave, emanating from thecenter of the explosion, and, second, the fires which were causedeither by the heat of the explosion itself or by the collapse ofbuildings containing stoves, electrical fixtures, or any otherequipment which might produce what is known as a secondary fire, andsubsequent spread of these fires. 

The blast produced by the atomic bomb has already been stated to beapproximately equivalent to that of 20, 000 tons of T. N. T. Given thisfigure, one may calculate the expected peak pressures in the air, atvarious distances from the center of the explosion, which occurredfollowing detonation of the bomb. The peak pressures which werecalculated before the bombs were dropped agreed very closely with thosewhich were actually experienced in the cities during the attack ascomputed by Allied experts in a number of ingenious ways after theoccupation of Japan. 

The blast of pressure from the atomic bombs differed from that ofordinary high explosive bombs in three main ways:

A. Downward thrust. Because the explosions were well up in the air, much of the damage resulted from a downward pressure. This pressure ofcourse most largely effected flat roofs. Some telegraph and otherpoles immediately below the explosion remained upright while those atgreater distances from the center of damage, being more largely exposedto a horizontal thrust from the blast pressure waves, were overturnedor tilted. Trees underneath the explosion remained upright but hadtheir branches broken downward. 

B. Mass distortion of buildings. An ordinary bomb can damage only apart of a large building, which may then collapse further under theaction of gravity. But the blast wave from an atomic bomb is so largethat it can engulf whole buildings, no matter how great their size, pushing them over as though a giant hand had given them a shove. 

C. Long duration of the positive pressure pulse and consequent smalleffect of the negative pressure, or suction, phase. In any explosion, the positive pressure exerted by the blast lasts for a definite periodof time (usually a small fraction of a second) and is then followed bya somewhat longer period of negative pressure, or suction. Thenegative pressure is always much weaker than the positive, but inordinary explosions the short duration of the positive pulse results inmany structures not having time to fail in that phase, while they areable to fail under the more extended, though weaker, negative pressure. But the duration of the positive pulse is approximately proportional tothe 1/3 power of the size of the explosive charge. Thus, if therelation held true throughout the range in question, a 10-ton T. N. T. Explosion would have a positive pulse only about 1/14th as long as thatof a 20, 000-ton explosion. Consequently, the atomic explosions hadpositive pulses so much longer then those of ordinary explosives thatnearly all failures probably occurred during this phase, and verylittle damage could be attributed to the suction which followed. 

One other interesting feature was the combination of flash ignition andcomparative slow pressure wave. Some objects, such as thin, dry woodenslats, were ignited by the radiated flash heat, and then their fireswere blown out some time later (depending on their distance from X) bythe pressure blast which followed the flash radiation. 

CALCULATIONS OF THE PEAK PRESSURE OF THE BLAST WAVE

Several ingenious methods were used by the various investigators todetermine, upon visiting the wrecked cities, what had actually been thepeak pressures exerted by the atomic blasts. These pressures werecomputed for various distances from X, and curves were then plottedwhich were checked against the theoretical predictions of what thepressures would be. A further check was afforded from the readingsobtained by the measuring instruments which were dropped by parachuteat each atomic attack. The peak pressure figures gave a direct clue tothe equivalent T. N. T. Tonnage of the atomic bombs, since the pressuresdeveloped by any given amount of T. N. T. Can be calculated easily. 

One of the simplest methods of estimating the peak pressure is fromcrushing of oil drums, gasoline cans, or any other empty thin metalvessel with a small opening. The assumption made is that the blastwave pressure comes on instantaneously, the resulting pressure on thecan is more than the case can withstand, and the walls collapse inward. The air inside is compressed adiabatically to such a point that thepressure inside is less by a certain amount than the pressure outside, this amount being the pressure difference outside and in that the wallscan stand in their crumpled condition. The uncertainties involved are, first, that some air rushes in through any opening that the can mayhave, and thus helps to build up the pressure inside; and, second, thatas the pressure outside falls, the air inside cannot escapesufficiently fast to avoid the walls of the can being blown out againto some extent. These uncertainties are such that estimates ofpressure based on this method are on the low side, i. E. , they areunderestimated. 

Another method of calculating the peak-pressure is through the bendingof steel flagpoles, or lightning conductors, away from the explosion. It is possible to calculate the drag on a pole or rod in an airstreamof a certain density and velocity; by connecting this drag with thestrength of the pole in question, a determination of the pressure wavemay be obtained. 

Still another method of estimating the peak pressure is through theoverturning of memorial stones, of which there are a great quantity inJapan. The dimensions of the stones can be used along with known dataon the pressure exerted by wind against flat surfaces, to calculate thedesired figure. 

LONG RANGE BLAST DAMAGE

There was no consistency in the long range blast damage. Observersoften thought that they had found the limit, and then 2, 000 feetfarther away would find further evidence of damage. 

The most impressive long range damage was the collapse of some of thebarracks sheds at Kamigo, 23, 000 feet south of X in Nagasaki. It wasremarkable to see some of the buildings intact to the last details, including the roof and even the windows, and yet next to them a similarbuilding collapsed to ground level. 

The limiting radius for severe displacement of roof tiles in Nagasakiwas about 10, 000 feet although isolated cases were found up to 16, 000feet. In Hiroshima the general limiting radius was about 8, 000 feet;however, even at a distance of 26, 000 feet from X in Hiroshima, sometiles were displaced. 

At Mogi, 7 miles from X in Nagasaki, over steep hills over 600 feethigh, about 10% of the glass came out. In nearer, sequesteredlocalities only 4 miles from X, no damage of any kind was caused. Aninteresting effect was noted at Mogi; eyewitnesses said that theythought a raid was being made on the place; one big flash was seen, then a loud roar, followed at several second intervals by half a dozenother loud reports, from all directions. These successive reports wereobviously reflections from the hills surrounding Mogi. 

GROUND SHOCK

The ground shock in most cities was very light. Water pipes stillcarried water and where leaks were visible they were mainly aboveground. Virtually all of the damage to underground utilities wascaused by the collapse of buildings rather than by any direct exertionof the blast pressure. This fact of course resulted from the bombs'having been exploded high in the air. 

SHIELDING, OR SCREENING FROM BLAST

In any explosion, a certain amount of protection from blast may begained by having any large and substantial object between the protectedobject and the center of the explosion. This shielding effect wasnoticeable in the atomic explosions, just as in ordinary cases, although the magnitude of the explosions and the fact that theyoccurred at a considerable height in the air caused marked differencesfrom the shielding which would have characterized ordinary bombexplosions. 

The outstanding example of shielding was that afforded by the hills inthe city of Nagasaki; it was the shielding of these hills whichresulted in the smaller area of devastation in Nagasaki despite thefact that the bomb used there was not less powerful. The hills gaveeffective shielding only at such distances from the center of explosionthat the blast pressure was becoming critical--that is, was only barelysufficient to cause collapse--for the structure. Houses built inravines in Nagasaki pointing well away from the center of the explosionsurvived without damage, but others at similar distances in ravinespointing toward the center of explosion were greatly damaged. In thenorth of Nagasaki there was a small hamlet about 8, 000 feet from thecenter of explosion; one could see a distinctive variation in theintensity of damage across the hamlet, corresponding with the shadowsthrown by a sharp hill. 

The best example of shielding by a hill was southeast of the center ofexplosion in Nagasaki. The damage at 8, 000 feet from X consisted oflight plaster damage and destruction of about half the windows. Thesebuildings were of European type and were on the reverse side of a steephill. At the same distance to the south-southeast the damage wasconsiderably greater, i. E. , all windows and frames, doors, were damagedand heavy plaster damage and cracks in the brick work also appeared. The contrast may be illustrated also by the fact that at the NagasakiPrefectural office at 10, 800 feet the damage was bad enough for thebuilding to be evacuated, while at the Nagasaki Normal School to whichthe Prefectural office had been moved, at the same distance, the damagewas comparatively light. 

Because of the height of the bursts no evidence was expected of theshielding of one building by another, at least up to a considerableradius. It was in fact difficult to find any evidence at any distanceof such shielding. There appeared to have been a little shielding ofthe building behind the Administration Building of the Torpedo Works inNagasaki, but the benefits were very slight. There was also someevidence that the group of buildings comprising the Medical School inNagasaki did afford each other mutual protection. On the whole, however, shielding of one building by another was not noticeable. 

There was one other peculiar type of shielding, best exhibited by theworkers' houses to the north of the torpedo plant in Nagasaki. Thesewere 6, 000 to 7, 000 feet north of X. The damage to these houses wasnot nearly as bad as those over a thousand feet farther away from thecenter of explosion. It seemed as though the great destruction causedin the torpedo plant had weakened the blast a little, and the fullpower was not restored for another 1, 000 feet or more. 

FLASH BURN

As already stated, a characteristic feature of the atomic bomb, whichis quite foreign to ordinary explosives, is that a very appreciablefraction of the energy liberated goes into radiant heat and light. Fora sufficiently large explosion, the flash burn produced by thisradiated energy will become the dominant cause of damage, since thearea of burn damage will increase in proportion to the energy released, whereas the area of blast damage increases only with the two-thirdspower of the energy. Although such a reversal of the mechanism ofdamage was not achieved in the Hiroshima and Nagasaki bombs, theeffects of the flash were, however, very evident, and many casualtiesresulted from flash burns. A discussion of the casualties caused byflash burns will be given later; in this section will be described theother flash effects which were observed in the two cities. 

The duration of the heat radiation from the bomb is so short, just afew thousandths of a second, that there is no time for the energyfalling on a surface to be dissipated by thermal defusion; the flashburn is typically a surface effect. In other words the surface ofeither a person or an object exposed to the flash is raised to a veryhigh temperature while immediately beneath the surface very little risein temperature occurs. 

The flash burning of the surface of objects, particularly woodenobjects, occurred in Hiroshima up to a radius of 9, 500 feet from X; atNagasaki burns were visible up to 11, 000 feet from X. The charring andblackening of all telephone poles, trees and wooden posts in the areasnot destroyed by the general fire occurred only on the side facing thecenter of explosion and did not go around the corners of buildings orhills. The exact position of the explosion was in fact accuratelydetermined by taking a number of sights from various objects which hadbeen flash burned on one side only. 

To illustrate the effects of the flash burn, the following describes anumber of examples found by an observer moving northward from thecenter of explosion in Nagasaki. First occurred a row of fence postsat the north edge of the prison hill, at 0. 3 miles from X. The top andupper part of these posts were heavily charred. The charring on thefront of the posts was sharply limited by the shadow of a wall. Thiswall had however been completely demolished by the blast, which ofcourse arrived some time after the flash. At the north edge of theTorpedo works, 1. 05 miles from X, telephone poles were charred to adepth of about 0. 5 millimeters. A light piece of wood similar to theflat side of an orange crate, was found leaning against one of thetelephone poles. Its front surface was charred the same way as thepole, but it was evident that it had actually been ignited. The woodwas blackened through a couple of cracks and nail holes, and around theedges onto the back surface. It seemed likely that this piece of woodhad flamed up under the flash for a few seconds before the flame wasblown out by the wind of the blast. Farther out, between 1. 05 and 1. 5miles from the explosion, were many trees and poles showing ablackening. Some of the poles had platforms near the top. The shadowscast by the platforms were clearly visible and showed that the bomb haddetonated at a considerable height. The row of poles turned north andcrossed the mountain ridge; the flash burn was plainly visible all theway to the top of the ridge, the farthest burn observed being at 2. 0miles from X. 

Another striking effect of the flash burn was the autumnal appearanceof the bowl formed by the hills on three sides of the explosion point. The ridges are about 1. 5 miles from X. Throughout this bowl thefoliage turned yellow, although on the far side of the ridges thecountryside was quite green. This autumnal appearance of the treesextended to about 8, 000 feet from X. 

However, shrubs and small plants quite near the center of explosion inHiroshima, although stripped of leaves, had obviously not been killed. Many were throwing out new buds when observers visited the city. 

There are two other remarkable effects of the heat radiated from thebomb explosion. The first of these is the manner in which heatroughened the surface of polished granite, which retained its polishonly where it was shielded from the radiated heat travelling instraight lines from the explosion. This roughening by radiated heatcaused by the unequal expansion of the constituent crystals of thestone; for granite crystals the melting temperature is about 600 degcentigrade. Therefore the depth of roughening and ultimate flaking ofthe granite surface indicated the depth to which this temperatureoccurred and helped to determine the average ground temperatures in theinstant following the explosion. This effect was noted for distancesabout 1 1/2 times as great in Nagasaki as in Hiroshima. 

The second remarkable effect was the bubbling of roof tile. The sizeof the bubbles and their extent was proportional to their nearness tothe center of explosion and also depended on how squarely the tileitself was faced toward the explosion. The distance ratio of thiseffect between Nagasaki and Hiroshima was about the same as for theflaking of polished granite. 

Various other effects of the radiated heat were noted, including thelightening of asphalt road surfaces in spots which had not beenprotected from the radiated heat by any object such as that of a personwalking along the road. Various other surfaces were discolored indifferent ways by the radiated heat. 

As has already been mentioned the fact that radiant heat traveled onlyin straight lines from the center of explosion enabled observers todetermine the direction toward the center of explosion from a number ofdifferent points, by observing the "shadows" which were cast byintervening objects where they shielded the otherwise exposed surfaceof some object. Thus the center of explosion was located withconsiderable accuracy. In a number of cases these "shadows" also gavean indication of the height of burst of the bomb and occasionally adistinct penumbra was found which enabled observers to calculate thediameter of the ball of fire at the instant it was exerting the maximumcharring or burning effect. 

One more interesting feature connected with heat radiation was thecharring of fabric to different degrees depending upon the color of thefabric. A number of instances were recorded in which persons wearingclothing of various colors received burns greatly varying in degree, the degree of burn depending upon the color of the fabric over the skinin question. For example a shirt of alternate light and dark graystripes, each about 1/8 of an inch wide, had the dark stripescompletely burned out but the light stripes were undamaged; and a pieceof Japanese paper exposed nearly 1 1/2 miles from X had the characterswhich were written in black ink neatly burned out. 

CHARACTERISTICS OF THE INJURIES TO PERSONS

Injuries to persons resulting from the atomic explosions were of thefollowing types:

 A. Burns, from 1. Flash radiation of heat 2. Fires started by the explosions. B. Mechanical injuries from collapse of buildings, flying debris, etc. C. Direct effects of the high blast pressure, i. E. , straight compression. D. Radiation injuries, from the instantaneous emission of gamma rays and neutrons. 

It is impossible to assign exact percentages of casualties to each ofthe types of injury, because so many victims were injured by more thanone effect of the explosions. However, it is certain that the greaterpart of the casualties resulted from burns and mechanical injures. Col. Warren, one of America's foremost radioligists, stated it isprobable that 7 per cent or less of the deaths resulted primarily fromradiation disease. 

The greatest single factor influencing the occurrence of casualties wasthe distance of the person concerned from the center of explosion. 

Estimates based on the study of a selected group of 900 patientsindicated that total casualties occurred as far out as 14, 000 feet atNagasaki and 12, 000 feet at Hiroshima. 

Burns were suffered at a considerable greater distance from X than anyother type of injury, and mechanical injuries farther out thanradiation effects. 

Medical findings show that no person was injured by radioactivity whowas not exposed to the actual explosion of the bombs. No injuriesresulted from persistent radioactivity of any sort. 

BURNS

Two types of burns were observed. These are generally differentiatedas flame or fire burn and so-called flash burn. 

The early appearance of the flame burn as reported by the Japanese, andthe later appearance as observed, was not unusual. 

The flash burn presented several distinctive features. Marked rednessof the affected skin areas appeared almost immediately, according tothe Japanese, with progressive changes in the skin taking place over aperiod of a few hours. When seen after 50 days, the most distinctivefeature of these burns was their sharp limitation to exposed skin areasfacing the center of the explosion. For instance, a patient who hadbeen walking in a direction at right angles to a line drawn between himand the explosion, and whose arms were swinging, might have burns onlyon the outside of the arm nearest the center and on the inside of theother arm. 

Generally, any type of shielding protected the skin against flashburns, although burns through one, and very occasionally more, layersof clothing did occur in patients near the center. In such cases, itwas not unusual to find burns through black but not through whiteclothing, on the same patient. Flash burns also tended to involveareas where the clothes were tightly drawn over the skin, such as atthe elbows and shoulders. 

The Japanese report the incidence of burns in patients surviving morethan a few hours after the explosion, and seeking medical attention, ashigh as 95%. The total mortalities due to burns alone cannot beestimated with any degree of accuracy. As mentioned already, it isbelieved that the majority of all the deaths occurred immediately. Ofthese, the Japanese estimate that 75%, and most of the reports estimatethat over 50%, of the deaths were due to burns. 

In general, the incidence of burns was in direct proportion to thedistance from X. However, certain irregularities in this relationshipresult in the medical studies because of variations in the amount ofshielding from flash burn, and because of the lack of complete data onpersons killed outright close to X. 

The maximum distance from X at which flash burns were observed is ofparamount interest. It has been estimated that patients with burns atHiroshima were all less than 7, 500 feet from the center of theexplosion at the time of the bombing. At Nagasaki, patients with burnswere observed out to the remarkable distance of 13, 800 feet. 

MECHANICAL INJURIES

The mechanical injuries included fractures, lacerations, contusions, abrasions, and other effects to be expected from falling roofs, crumbling walls, flying debris and glass, and other indirect blasteffects. The appearance of these various types of mechanical injurieswas not remarkable to the medical authorities who studied them. 

It was estimated that patients with lacerations at Hiroshima were lessthan 10, 600 feet from X, whereas at Nagasaki they extended as far as12, 200 feet. 

The tremendous drag of wind, even as far as 1 mile from X, must haveresulted in many injuries and deaths. Some large pieces of a prisonwall, for example, were flung 80 feet, and many have gone 30 feet highbefore falling. The same fate must have befallen many persons, and thechances of a human being surviving such treatment are probably small. 

BLAST INJURIES

No estimate of the number of deaths or early symptoms due to blastpressure can be made. The pressures developed on the ground under theexplosions were not sufficient to kill more than those people very nearthe center of damage (within a few hundred feet at most). Very fewcases of ruptured ear drums were noted, and it is the general feelingof the medical authorities that the direct blast effects were notgreat. Many of the Japanese reports, which are believed to be false, describe immediate effects such as ruptured abdomens with protrudingintestines and protruding eyes, but no such results were actuallytraced to the effect of air pressure alone. 

RADIATION INJURIES

As pointed out in another section of this report the radiations fromthe nuclear explosions which caused injuries to persons were primarilythose experienced within the first second after the explosion; a fewmay have occurred later, but all occurred in the first minute. Theother two general types of radiation, viz. , radiation from scatteredfission products and induced radioactivity from objects near the centerof explosion, were definitely proved not to have caused any casualties. 

The proper designation of radiation injuries is somewhat difficult. Probably the two most direct designations are radiation injury andgamma ray injury. The former term is not entirely suitable in that itdoes not define the type of radiation as ionizing and allows possibleconfusion with other types of radiation (e. G. , infra-red). Theobjection to the latter term is that it limits the ionizing radiationto gamma rays, which were undoubtedly the most important; but thepossible contribution of neutron and even beta rays to the biologicaleffects cannot be entirely ignored. Radiation injury has the advantageof custom, since it is generally understood in medicine to refer toX-ray effect as distinguished from the effects of actinic radiation. Accordingly, radiation injury is used in this report to mean injury dueonly to ionizing radiation. 

According to Japanese observations, the early symptons in patientssuffering from radiation injury closely resembled the symptons observedin patients receiving intensive roentgen therapy, as well as thoseobserved in experimental animals receiving large doses of X-rays. Theimportant symptoms reported by the Japanese and observed by Americanauthorities were epilation (lose of hair), petechiae (bleeding into theskin), and other hemorrhagic manifestations, oropharyngeal lesions(inflammation of the mouth and throat), vomiting, diarrhea, and fever. 

Epilation was one of the most spectacular and obvious findings. Theappearance of the epilated patient was typical. The crown was involvedmore than the sides, and in many instances the resemblance to a monk'stonsure was striking. In extreme cases the hair was totally lost. Insome cases, re-growth of hair had begun by the time patients were seen50 days after the bombing. Curiously, epilation of hair other thanthat of the scalp was extremely unusual. 

Petechiae and other hemorrhagic manifestations were striking findings. Bleeding began usually from the gums and in the more seriously affectedwas soon evident from every possible source. Petechiae appeared on thelimbs and on pressure points. Large ecchymoses (hemorrhages under theskin) developed about needle punctures, and wounds partially healedbroke down and bled freely. Retinal hemorrhages occurred in many ofthe patients. The bleeding time and the coagulation time wereprolonged. The platelets (coagulation of the blood) werecharacteristically reduced in numbers. 

Nausea and vomiting appearing within a few hours after the explosionwas reported frequently by the Japanese. This usually had subsided bythe following morning, although occasionally it continued for two orthree days. Vomiting was not infrequently reported and observed duringthe course of the later symptoms, although at these times it generallyappeared to be related to other manifestation of systemic reactionsassociated with infection. 

Diarrhea of varying degrees of severity was reported and observed. Inthe more severe cases, it was frequently bloody. For reasons which arenot yet clear, the diarrhea in some cases was very persistent. 

Lesions of the gums, and the oral mucous membrane, and the throat wereobserved. The affected areas became deep red, then violacious incolor; and in many instances ulcerations and necrosis (breakdown oftissue) followed. Blood counts done and recorded by the Japanese, aswell as counts done by the Manhattan Engineer District Group, on suchpatients regularly showed leucopenia (low-white blood cell count). Inextreme cases the white blood cell count was below 1, 000 (normal countis around 7, 000). In association with the leucopenia and theoropharyngeal lesions, a variety of other infective processes wereseen. Wounds and burns which were healing adequately suppurated andserious necrosis occurred. At the same time, similar ulcerations wereobserved in the larynx, bowels, and in females, the gentalia. Feverusually accompanied these lesions. 

Eye injuries produced by the atomic bombings in both cities were thesubject of special investigations. The usual types of mechanicalinjuries were seen. In addition, lesions consisting of retinalhemorrhage and exudation were observed and 75% of the patients showingthem had other signs of radiation injury. 

The progress of radiation disease of various degrees of severity isshown in the following table:

 Summary of Radiation Injury Clinical Symptoms and Findings

 Day after Explo- sion Most Severe Moderately Severe Mild 1. 1. Nausea and vomiting 1. Nausea and vomiting 2. After 1-2 hours. After 1-2 hours. 3. NO DEFINITE SYMPTOMS 4. 5. 2. Diarrhea 6. 3. Vomiting NO DEFINITE SYMPTOMS 7. 4. Inflammation of the mouth and throat 8. 5. Fever 9. 6. Rapid emaciation 10. Death NO DEFINITE SYMPTOMS 11. (Mortality probably 2. Beginning epilation. 12. 100%) 13. 14. 15. 16. 17. 18. 3. Loss of appetite 19. And general malaise. 1. Epilation 20. 4. Fever. 2. Loss of appetite 21. 5. Severe inflammation and malaise. 22. Of the mouth and throat 3. Sore throat. 23. 4. Pallor. 24. 5. Petechiae 25. 6. Diarrhea 26. 7. Moderate emacia- 27. 6. Pallor. Tion. 28. 7. Petechiae, diarrhea 29. And nose bleeds (Recovery unless com- 30. Plicated by previous 31. 8. Rapid emaciation poor health or Death super-imposed in- (Mortality probably 50%) juries or infec- tion). 

It was concluded that persons exposed to the bombs at the time ofdetonation did show effects from ionizing radiation and that some ofthese patients, otherwise uninjured, died. Deaths from radiation beganabout a week after exposure and reached a peak in 3 to 4 weeks. Theypractically ceased to occur after 7 to 8 weeks. 

Treatment of the burns and other physical injuries was carried out bythe Japanese by orthodox methods. Treatment of radiation effects bythem included general supportative measures such as rest and highvitamin and caloric diets. Liver and calcium preparations wereadministered by injection and blood transfusions were used to combathemorrhage. Special vitamin preparations and other special drugs usedin the treatment of similar medical conditions were used by AmericanArmy Medical Corps officers after their arrival. Although the generalmeasures instituted were of some benefit no definite effect of any ofthe specific measures on the course of the disease could bedemonstrated. The use of sulfonamide drugs by the Japanese andparticularly of penicillin by the American physicians after theirarrival undoubtedly helped control the infections and they appear to bethe single important type of treatment which may have effectivelyaltered the earlier course of these patients. 

One of the most important tasks assigned to the mission whichinvestigated the effects of the bombing was that of determining if theradiation effects were all due to the instantaneous discharges at thetime of the explosion, or if people were being harmed in addition frompersistent radioactivity. This question was investigated from twopoints of view. Direct measurements of persistent radioactivity weremade at the time of the investigation. From these measurements, calculations were made of the graded radiation dosages, i. E. , the totalamount of radiation which could have been absorbed by any person. These calculations showed that the highest dosage which would have beenreceived from persistent radioactivity at Hiroshima was between 6 and25 roentgens of gamma radiation; the highest in the Nagasaki Area wasbetween 30 and 110 roentgens of gamma radiation. The latter figuredoes not refer to the city itself, but to a localized area in theNishiyama District. In interpreting these findings it must beunderstood that to get these dosages, one would have had to remain atthe point of highest radioactivity for 6 weeks continuously, from thefirst hour after the bombing. It is apparent therefore that insofar ascould be determined at Hiroshima and Nagasaki, the residual radiationalone could not have been detrimental to the health of persons enteringand living in the bombed areas after the explosion. 

The second approach to this question was to determine if any personsnot in the city at the time of the explosion, but coming in immediatelyafterwards exhibited any symptoms or findings which might have been dueto persistence induced radioactivity. By the time of the arrival ofthe Manhattan Engineer District group, several Japanese studies hadbeen done on such persons. None of the persons examined in any ofthese studies showed any symptoms which could be attributed toradiation, and their actual blood cell counts were consistently withinthe normal range. Throughout the period of the Manhattan EngineerDistrict investigation, Japanese doctors and patients were repeatedlyrequested to bring to them any patients who they thought might beexamples of persons harmed from persistent radioactivity. No suchsubjects were found. 

It was concluded therefore as a result of these findings and lack offindings, that although a measurable quantity of induced radioactivitywas found, it had not been sufficient to cause any harm to personsliving in the two cities after the bombings. 

SHIELDING FROM RADIATION

Exact figures on the thicknesses of various substances to providecomplete or partial protection from the effects of radiation inrelation to the distance from the center of explosion, cannot bereleased at this time. Studies of collected data are still under way. It can be stated, however, that at a reasonable distance, say about 1/2mile from the center of explosion, protection to persons from radiationinjury can be afforded by a layer of concrete or other material whosethickness does not preclude reasonable construction. 

Radiation ultimately caused the death of the few persons not killed byother effects and who were fully exposed to the bombs up to a distanceof about 1/2 mile from X. The British Mission has estimated thatpeople in the open had a 50% chance of surviving the effects ofradiation at 3/4 of a mile from X. 

EFFECTS OF THE ATOMIC BOMBINGS ON THE INHABITANTS OF THE BOMBED CITIES

In both Hiroshima and Nagasaki the tremendous scale of the disasterlargely destroyed the cities as entities. Even the worst of all otherprevious bombing attacks on Germany and Japan, such as the incendiaryraids on Hamburg in 1943 and on Tokyo in 1945, were not comparable tothe paralyzing effect of the atomic bombs. In addition to the hugenumber of persons who were killed or injuried so that their services inrehabilitation were not available, a panic flight of the populationtook place from both cities immediately following the atomicexplosions. No significant reconstruction or repair work wasaccomplished because of the slow return of the population; at the endof November 1945 each of the cities had only about 140, 000 people. Although the ending of the war almost immediately after the atomicbombings removed much of the incentive of the Japanese people towardimmediate reconstruction of their losses, their paralysis was stillremarkable. Even the clearance of wreckage and the burning of the manybodies trapped in it were not well organized some weeks after thebombings. As the British Mission has stated, "the impression whichboth cities make is of having sunk, in an instant and without astruggle, to the most primitive level. "

Aside from physical injury and damage, the most significant effect ofthe atomic bombs was the sheer terror which it struck into the peoplesof the bombed cities. This terror, resulting in immediate hystericalactivity and flight from the cities, had one especially pronouncedeffect: persons who had become accustomed to mass air raids had grownto pay little heed to single planes or small groups of planes, butafter the atomic bombings the appearance of a single plane caused moreterror and disruption of normal life than the appearance of manyhundreds of planes had ever been able to cause before. The effect ofthis terrible fear of the potential danger from even a single enemyplane on the lives of the peoples of the world in the event of anyfuture war can easily be conjectured. 

The atomic bomb did not alone win the war against Japan, but it mostcertainly ended it, saving the thousands of Allied lives that wouldhave been lost in any combat invasion of Japan. 

EYEWITNESS ACCOUNT Hiroshima--August 6th, 1945

by Father John A. Siemes, professor of modern philosphy at Tokyo'sCatholic University

Up to August 6th, occasional bombs, which did no great damage, hadfallen on Hiroshima. Many cities roundabout, one after the other, weredestroyed, but Hiroshima itself remained protected. There were almostdaily observation planes over the city but none of them dropped a bomb. The citizens wondered why they alone had remained undisturbed for solong a time. There were fantastic rumors that the enemy had somethingspecial in mind for this city, but no one dreamed that the end wouldcome in such a fashion as on the morning of August 6th. 

August 6th began in a bright, clear, summer morning. About seveno'clock, there was an air raid alarm which we had heard almost everyday and a few planes appeared over the city. No one paid any attentionand at about eight o'clock, the all-clear was sounded. I am sitting inmy room at the Novitiate of the Society of Jesus in Nagatsuke; duringthe past half year, the philosophical and theological section of ourMission had been evacuated to this place from Tokyo. The Novitiate issituated approximately two kilometers from Hiroshima, half-way up thesides of a broad valley which stretches from the town at sea level intothis mountainous hinterland, and through which courses a river. Frommy window, I have a wonderful view down the valley to the edge of thecity. 

Suddenly--the time is approximately 8:14--the whole valley is filled bya garish light which resembles the magnesium light used in photography, and I am conscious of a wave of heat. I jump to the window to find outthe cause of this remarkable phenomenon, but I see nothing more thanthat brilliant yellow light. As I make for the door, it doesn't occurto me that the light might have something to do with enemy planes. Onthe way from the window, I hear a moderately loud explosion which seemsto come from a distance and, at the same time, the windows are brokenin with a loud crash. There has been an interval of perhaps tenseconds since the flash of light. I am sprayed by fragments of glass. The entire window frame has been forced into the room. I realize nowthat a bomb has burst and I am under the impression that it explodeddirectly over our house or in the immediate vicinity. 

I am bleeding from cuts about the hands and head. I attempt to get outof the door. It has been forced outwards by the air pressure and hasbecome jammed. I force an opening in the door by means of repeatedblows with my hands and feet and come to a broad hallway from whichopen the various rooms. Everything is in a state of confusion. Allwindows are broken and all the doors are forced inwards. Thebookshelves in the hallway have tumbled down. I do not note a secondexplosion and the fliers seem to have gone on. Most of my colleagueshave been injured by fragments of glass. A few are bleeding but nonehas been seriously injured. All of us have been fortunate since it isnow apparent that the wall of my room opposite the window has beenlacerated by long fragments of glass. 

We proceed to the front of the house to see where the bomb has landed. There is no evidence, however, of a bomb crater; but the southeastsection of the house is very severely damaged. Not a door nor a windowremains. The blast of air had penetrated the entire house from thesoutheast, but the house still stands. It is constructed in a Japanesestyle with a wooden framework, but has been greatly strengthened by thelabor of our Brother Gropper as is frequently done in Japanese homes. Only along the front of the chapel which adjoins the house, threesupports have given way (it has been made in the manner of Japanesetemple, entirely out of wood. )

Down in the valley, perhaps one kilometer toward the city from us, several peasant homes are on fire and the woods on the opposite side ofthe valley are aflame. A few of us go over to help control the flames. While we are attempting to put things in order, a storm comes up and itbegins to rain. Over the city, clouds of smoke are rising and I hear afew slight explosions. I come to the conclusion that an incendiarybomb with an especially strong explosive action has gone off down inthe valley. A few of us saw three planes at great altitude over thecity at the time of the explosion. I, myself, saw no aircraftwhatsoever. 

Perhaps a half-hour after the explosion, a procession of people beginsto stream up the valley from the city. The crowd thickenscontinuously. A few come up the road to our house. We give them firstaid and bring them into the chapel, which we have in the meantimecleaned and cleared of wreckage, and put them to rest on the straw matswhich constitute the floor of Japanese houses. A few display horriblewounds of the extremities and back. The small quantity of fat which wepossessed during this time of war was soon used up in the care of theburns. Father Rektor who, before taking holy orders, had studiedmedicine, ministers to the injured, but our bandages and drugs are soongone. We must be content with cleansing the wounds. 

More and more of the injured come to us. The least injured drag themore seriously wounded. There are wounded soldiers, and motherscarrying burned children in their arms. From the houses of the farmersin the valley comes word: "Our houses are full of wounded and dying. Can you help, at least by taking the worst cases?" The wounded comefrom the sections at the edge of the city. They saw the bright light, their houses collapsed and buried the inmates in their rooms. Thosethat were in the open suffered instantaneous burns, particularly on thelightly clothed or unclothed parts of the body. Numerous fires sprangup which soon consumed the entire district. We now conclude that theepicenter of the explosion was at the edge of the city near theJokogawa Station, three kilometers away from us. We are concernedabout Father Kopp who that same morning, went to hold Mass at theSisters of the Poor, who have a home for children at the edge of thecity. He had not returned as yet. 

Toward noon, our large chapel and library are filled with the seriouslyinjured. The procession of refugees from the city continues. Finally, about one o'clock, Father Kopp returns, together with the Sisters. Their house and the entire district where they live has burned to theground. Father Kopp is bleeding about the head and neck, and he has alarge burn on the right palm. He was standing in front of the nunneryready to go home. All of a sudden, he became aware of the light, feltthe wave of heat and a large blister formed on his hand. The windowswere torn out by the blast. He thought that the bomb had fallen in hisimmediate vicinity. The nunnery, also a wooden structure made by ourBrother Gropper, still remained but soon it is noted that the house isas good as lost because the fire, which had begun at many points in theneighborhood, sweeps closer and closer, and water is not available. There is still time to rescue certain things from the house and to burythem in an open spot. Then the house is swept by flame, and they fighttheir way back to us along the shore of the river and through theburning streets. 

Soon comes news that the entire city has been destroyed by theexplosion and that it is on fire. What became of Father Superior andthe three other Fathers who were at the center of the city at theCentral Mission and Parish House? We had up to this time not giventhem a thought because we did not believe that the effects of the bombencompassed the entire city. Also, we did not want to go into townexcept under pressure of dire necessity, because we thought that thepopulation was greatly perturbed and that it might take revenge on anyforeigners which they might consider spiteful onlookers of theirmisfortune, or even spies. 

Father Stolte and Father Erlinghagen go down to the road which is stillfull of refugees and bring in the seriously injured who have sunken bythe wayside, to the temporary aid station at the village school. Thereiodine is applied to the wounds but they are left uncleansed. Neitherointments nor other therapeutic agents are available. Those that havebeen brought in are laid on the floor and no one can give them anyfurther care. What could one do when all means are lacking? Underthose circumstances, it is almost useless to bring them in. Among thepassersby, there are many who are uninjured. In a purposeless, insensate manner, distraught by the magnitude of the disaster most ofthem rush by and none conceives the thought of organizing help on hisown initiative. They are concerned only with the welfare of their ownfamilies. It became clear to us during these days that the Japanesedisplayed little initiative, preparedness, and organizational skill inpreparation for catastrophes. They failed to carry out any rescue workwhen something could have been saved by a cooperative effort, andfatalistically let the catastrophe take its course. When we urged themto take part in the rescue work, they did everything willingly, but ontheir own initiative they did very little. 

At about four o'clock in the afternoon, a theology student and twokindergarten children, who lived at the Parish House and adjoiningbuildings which had burned down, came in and said that Father SuperiorLaSalle and Father Schiffer had been seriously injured and that theyhad taken refuge in Asano Park on the river bank. It is obvious thatwe must bring them in since they are too weak to come here on foot. 

Hurriedly, we get together two stretchers and seven of us rush towardthe city. Father Rektor comes along with food and medicine. Thecloser we get to the city, the greater is the evidence of destructionand the more difficult it is to make our way. The houses at the edgeof the city are all severely damaged. Many have collapsed or burneddown. Further in, almost all of the dwellings have been damaged byfire. Where the city stood, there is a gigantic burned-out scar. Wemake our way along the street on the river bank among the burning andsmoking ruins. Twice we are forced into the river itself by the heatand smoke at the level of the street. 

Frightfully burned people beckon to us. Along the way, there are manydead and dying. On the Misasi Bridge, which leads into the inner citywe are met by a long procession of soldiers who have suffered burns. They drag themselves along with the help of staves or are carried bytheir less severely injured comrades... An endless procession of theunfortunate. 

Abandoned on the bridge, there stand with sunken heads a number ofhorses with large burns on their flanks. On the far side, the cementstructure of the local hospital is the only building that remainsstanding. Its interior, however, has been burned out. It acts as alandmark to guide us on our way. 

Finally we reach the entrance of the park. A large proportion of thepopulace has taken refuge there, but even the trees of the park are onfire in several places. Paths and bridges are blocked by the trunks offallen trees and are almost impassable. We are told that a high wind, which may well have resulted from the heat of the burning city, hasuprooted the large trees. It is now quite dark. Only the fires, whichare still raging in some places at a distance, give out a little light. 

At the far corner of the park, on the river bank itself, we at lastcome upon our colleagues. Father Schiffer is on the ground pale as aghost. He has a deep incised wound behind the ear and has lost so muchblood that we are concerned about his chances for survival. The FatherSuperior has suffered a deep wound of the lower leg. Father Cieslikand Father Kleinsorge have minor injuries but are completely exhausted. 

While they are eating the food that we have brought along, they tell usof their experiences. They were in their rooms at the Parish House--itwas a quarter after eight, exactly the time when we had heard theexplosion in Nagatsuke--when came the intense light and immediatelythereafter the sound of breaking windows, walls and furniture. Theywere showered with glass splinters and fragments of wreckage. FatherSchiffer was buried beneath a portion of a wall and suffered a severehead injury. The Father Superior received most of the splinters in hisback and lower extremity from which he bled copiously. Everything wasthrown about in the rooms themselves, but the wooden framework of thehouse remained intact. The solidity of the structure which was thework of Brother Gropper again shone forth. 

They had the same impression that we had in Nagatsuke: that the bombhad burst in their immediate vicinity. The Church, school, and allbuildings in the immediate vicinity collapsed at once. Beneath theruins of the school, the children cried for help. They were freed withgreat effort. Several others were also rescued from the ruins ofnearby dwellings. Even the Father Superior and Father Schiffer despitetheir wounds, rendered aid to others and lost a great deal of blood inthe process. 

In the meantime, fires which had begun some distance away are ragingeven closer, so that it becomes obvious that everything would soon burndown. Several objects are rescued from the Parish House and wereburied in a clearing in front of the Church, but certain valuables andnecessities which had been kept ready in case of fire could not befound on account of the confusion which had been wrought. It is hightime to flee, since the oncoming flames leave almost no way open. Fukai, the secretary of the Mission, is completely out of his mind. Hedoes not want to leave the house and explains that he does not want tosurvive the destruction of his fatherland. He is completely uninjured. Father Kleinsorge drags him out of the house on his back and he isforcefully carried away. 

Beneath the wreckage of the houses along the way, many have beentrapped and they scream to be rescued from the oncoming flames. Theymust be left to their fate. The way to the place in the city to whichone desires to flee is no longer open and one must make for Asano Park. Fukai does not want to go further and remains behind. He has not beenheard from since. In the park, we take refuge on the bank of theriver. A very violent whirlwind now begins to uproot large trees, andlifts them high into the air. As it reaches the water, a waterspoutforms which is approximately 100 meters high. The violence of thestorm luckily passes us by. Some distance away, however, wherenumerous refugees have taken shelter, many are blown into the river. Almost all who are in the vicinity have been injured and have lostrelatives who have been pinned under the wreckage or who have been lostsight of during the flight. There is no help for the wounded and somedie. No one pays any attention to a dead man lying nearby. 

The transportation of our own wounded is difficult. It is not possibleto dress their wounds properly in the darkness, and they bleed againupon slight motion. As we carry them on the shaky litters in the darkover fallen trees of the park, they suffer unbearable pain as theresult of the movement, and lose dangerously large quantities of blood. Our rescuing angel in this difficult situation is a Japanese Protestantpastor. He has brought up a boat and offers to take our wounded upstream to a place where progress is easier. First, we lower the littercontaining Father Schiffer into the boat and two of us accompany him. We plan to bring the boat back for the Father Superior. The boatreturns about one-half hour later and the pastor requests that severalof us help in the rescue of two children whom he had seen in the river. We rescue them. They have severe burns. Soon they suffer chills anddie in the park. 

The Father Superior is conveyed in the boat in the same manner asFather Schiffer. The theology student and myself accompany him. Father Cieslik considers himself strong enough to make his way on footto Nagatsuke with the rest of us, but Father Kleinsorge cannot walk sofar and we leave him behind and promise to come for him and thehousekeeper tomorrow. From the other side of the stream comes thewhinny of horses who are threatened by the fire. We land on a sandspit which juts out from the shore. It is full of wounded who havetaken refuge there. They scream for aid for they are afraid ofdrowning as the river may rise with the sea, and cover the sand spit. They themselves are too weak to move. However, we must press on andfinally we reach the spot where the group containing Father Schiffer iswaiting. 

Here a rescue party had brought a large case of fresh rice cakes butthere is no one to distribute them to the numerous wounded that lie allabout. We distribute them to those that are nearby and also helpourselves. The wounded call for water and we come to the aid of a few. Cries for help are heard from a distance, but we cannot approach theruins from which they come. A group of soldiers comes along the roadand their officer notices that we speak a strange language. He at oncedraws his sword, screamingly demands who we are and threatens to cut usdown. Father Laures, Jr. , seizes his arm and explains that we areGerman. We finally quiet him down. He thought that we might well beAmericans who had parachuted down. Rumors of parachutists were beingbandied about the city. The Father Superior who was clothed only in ashirt and trousers, complains of feeling freezing cold, despite thewarm summer night and the heat of the burning city. The one man amongus who possesses a coat gives it to him and, in addition, I give him myown shirt. To me, it seems more comfortable to be without a shirt inthe heat. 

In the meantime, it has become midnight. Since there are not enough ofus to man both litters with four strong bearers, we determine to removeFather Schiffer first to the outskirts of the city. From there, another group of bearers is to take over to Nagatsuke; the others areto turn back in order to rescue the Father Superior. I am one of thebearers. The theology student goes in front to warn us of the numerouswires, beams and fragments of ruins which block the way and which areimpossible to see in the dark. Despite all precautions, our progressis stumbling and our feet get tangled in the wire. Father Kruer fallsand carries the litter with him. Father Schiffer becomes halfunconscious from the fall and vomits. We pass an injured man who sitsall alone among the hot ruins and whom I had seen previously on the waydown. 

On the Misasa Bridge, we meet Father Tappe and Father Luhmer, who havecome to meet us from Nagatsuke. They had dug a family out of the ruinsof their collapsed house some fifty meters off the road. The father ofthe family was already dead. They had dragged out two girls and placedthem by the side of the road. Their mother was still trapped undersome beams. They had planned to complete the rescue and then to presson to meet us. At the outskirts of the city, we put down the litterand leave two men to wait until those who are to come from Nagatsukeappear. The rest of us turn back to fetch the Father Superior. 

Most of the ruins have now burned down. The darkness kindly hides themany forms that lie on the ground. Only occasionally in our quickprogress do we hear calls for help. One of us remarks that theremarkable burned smell reminds him of incinerated corpses. Theupright, squatting form which we had passed by previously is stillthere. 

Transportation on the litter, which has been constructed out of boards, must be very painful to the Father Superior, whose entire back is fullof fragments of glass. In a narrow passage at the edge of town, a carforces us to the edge of the road. The litter bearers on the left sidefall into a two meter deep ditch which they could not see in thedarkness. Father Superior hides his pain with a dry joke, but thelitter which is now no longer in one piece cannot be carried further. We decide to wait until Kinjo can bring a hand cart from Nagatsuke. Hesoon comes back with one that he has requisitioned from a collapsedhouse. We place Father Superior on the cart and wheel him the rest ofthe way, avoiding as much as possible the deeper pits in the road. 

About half past four in the morning, we finally arrive at theNovitiate. Our rescue expedition had taken almost twelve hours. Normally, one could go back and forth to the city in two hours. Ourtwo wounded were now, for the first time, properly dressed. I get twohours sleep on the floor; some one else has taken my own bed. Then Iread a Mass in gratiarum actionem, it is the 7th of August, theanniversary of the foundation of our society. Then we bestir ourselvesto bring Father Kleinsorge and other acquaintances out of the city. 

We take off again with the hand cart. The bright day now reveals thefrightful picture which last night's darkness had partly concealed. Where the city stood everything, as far as the eye could reach, is awaste of ashes and ruin. Only several skeletons of buildingscompletely burned out in the interior remain. The banks of the riverare covered with dead and wounded, and the rising waters have here andthere covered some of the corpses. On the broad street in theHakushima district, naked burned cadavers are particularly numerous. Among them are the wounded who are still alive. A few have crawledunder the burnt-out autos and trams. Frightfully injured forms beckonto us and then collapse. An old woman and a girl whom she is pullingalong with her fall down at our feet. We place them on our cart andwheel them to the hospital at whose entrance a dressing station hasbeen set up. Here the wounded lie on the hard floor, row on row. Onlythe largest wounds are dressed. We convey another soldier and an oldwoman to the place but we cannot move everybody who lies exposed in thesun. It would be endless and it is questionable whether those whom wecan drag to the dressing station can come out alive, because even herenothing really effective can be done. Later, we ascertain that thewounded lay for days in the burnt-out hallways of the hospital andthere they died. 

We must proceed to our goal in the park and are forced to leave thewounded to their fate. We make our way to the place where our churchstood to dig up those few belongings that we had buried yesterday. Wefind them intact. Everything else has been completely burned. In theruins, we find a few molten remnants of holy vessels. At the park, weload the housekeeper and a mother with her two children on the cart. Father Kleinsorge feels strong enough, with the aid of BrotherNobuhara, to make his way home on foot. The way back takes us onceagain past the dead and wounded in Hakushima. Again no rescue partiesare in evidence. At the Misasa Bridge, there still lies the familywhich the Fathers Tappe and Luhmer had yesterday rescued from theruins. A piece of tin had been placed over them to shield them fromthe sun. We cannot take them along for our cart is full. We give themand those nearby water to drink and decide to rescue them later. Atthree o'clock in the afternoon, we are back in Nagatsuka. 

After we have had a few swallows and a little food, Fathers Stolte, Luhmer, Erlinghagen and myself, take off once again to bring in thefamily. Father Kleinsorge requests that we also rescue two childrenwho had lost their mother and who had lain near him in the park. Onthe way, we were greeted by strangers who had noted that we were on amission of mercy and who praised our efforts. We now met groups ofindividuals who were carrying the wounded about on litters. As wearrived at the Misasa Bridge, the family that had been there was gone. They might well have been borne away in the meantime. There was agroup of soldiers at work taking away those that had been sacrificedyesterday. 

More than thirty hours had gone by until the first official rescueparty had appeared on the scene. We find both children and take themout of the park: a six-year old boy who was uninjured, and atwelve-year old girl who had been burned about the head, hands andlegs, and who had lain for thirty hours without care in the park. Theleft side of her face and the left eye were completely covered withblood and pus, so that we thought that she had lost the eye. When thewound was later washed, we noted that the eye was intact and that thelids had just become stuck together. On the way home, we took anothergroup of three refugees with us. They first wanted to know, however, of what nationality we were. They, too, feared that we might beAmericans who had parachuted in. When we arrived in Nagatsuka, it hadjust become dark. 

We took under our care fifty refugees who had lost everything. Themajority of them were wounded and not a few had dangerous burns. Father Rektor treated the wounds as well as he could with the fewmedicaments that we could, with effort, gather up. He had to confinehimself in general to cleansing the wounds of purulent material. Eventhose with the smaller burns are very weak and all suffered fromdiarrhea. In the farm houses in the vicinity, almost everywhere, thereare also wounded. Father Rektor made daily rounds and acted in thecapacity of a painstaking physician and was a great Samaritan. Ourwork was, in the eyes of the people, a greater boost for Christianitythan all our work during the preceding long years. 

Three of the severely burned in our house died within the next fewdays. Suddenly the pulse and respirations ceased. It is certainly asign of our good care that so few died. In the official aid stationsand hospitals, a good third or half of those that had been brought indied. They lay about there almost without care, and a very highpercentage succumbed. Everything was lacking: doctors, assistants, dressings, drugs, etc. In an aid station at a school at a nearbyvillage, a group of soldiers for several days did nothing except tobring in and cremate the dead behind the school. 

During the next few days, funeral processions passed our house frommorning to night, bringing the deceased to a small valley nearby. There, in six places, the dead were burned. People brought their ownwood and themselves did the cremation. Father Luhmer and Father Lauresfound a dead man in a nearby house who had already become bloated andwho emitted a frightful odor. They brought him to this valley andincinerated him themselves. Even late at night, the little valley waslit up by the funeral pyres. 

We made systematic efforts to trace our acquaintances and the familiesof the refugees whom we had sheltered. Frequently, after the passageof several weeks, some one was found in a distant village or hospitalbut of many there was no news, and these were apparently dead. We werelucky to discover the mother of the two children whom we had found inthe park and who had been given up for dead. After three weeks, shesaw her children once again. In the great joy of the reunion weremingled the tears for those whom we shall not see again. 

The magnitude of the disaster that befell Hiroshima on August 6th wasonly slowly pieced together in my mind. I lived through thecatastrophe and saw it only in flashes, which only gradually weremerged to give me a total picture. What actually happenedsimultaneously in the city as a whole is as follows: As a result of theexplosion of the bomb at 8:15, almost the entire city was destroyed ata single blow. Only small outlying districts in the southern andeastern parts of the town escaped complete destruction. The bombexploded over the center of the city. As a result of the blast, thesmall Japanese houses in a diameter of five kilometers, whichcompressed 99% of the city, collapsed or were blown up. Those who werein the houses were buried in the ruins. Those who were in the opensustained burns resulting from contact with the substance or raysemitted by the bomb. Where the substance struck in quantity, firessprang up. These spread rapidly. 

The heat which rose from the center created a whirlwind which waseffective in spreading fire throughout the whole city. Those who hadbeen caught beneath the ruins and who could not be freed rapidly, andthose who had been caught by the flames, became casualties. As much assix kilometers from the center of the explosion, all houses weredamaged and many collapsed and caught fire. Even fifteen kilometersaway, windows were broken. It was rumored that the enemy fliers hadspread an explosive and incendiary material over the city and then hadcreated the explosion and ignition. A few maintained that they saw theplanes drop a parachute which had carried something that exploded at aheight of 1, 000 meters. The newspapers called the bomb an "atomicbomb" and noted that the force of the blast had resulted from theexplosion of uranium atoms, and that gamma rays had been sent out as aresult of this, but no one knew anything for certain concerning thenature of the bomb. 

How many people were a sacrifice to this bomb? Those who had livedthrough the catastrophe placed the number of dead at at least 100, 000. Hiroshima had a population of 400, 000. Official statistics place thenumber who had died at 70, 000 up to September 1st, not counting themissing ... And 130, 000 wounded, among them 43, 500 severely wounded. Estimates made by ourselves on the basis of groups known to us showthat the number of 100, 000 dead is not too high. Near us there are twobarracks, in each of which forty Korean workers lived. On the day ofthe explosion, they were laboring on the streets of Hiroshima. Fourreturned alive to one barracks and sixteen to the other. 600 studentsof the Protestant girls' school worked in a factory, from which onlythirty to forty returned. Most of the peasant families in theneighborhood lost one or more of their members who had worked atfactories in the city. Our next door neighbor, Tamura, lost twochildren and himself suffered a large wound since, as it happened, hehad been in the city on that day. The family of our reader sufferedtwo dead, father and son; thus a family of five members suffered atleast two losses, counting only the dead and severely wounded. Theredied the Mayor, the President of the central Japan district, theCommander of the city, a Korean prince who had been stationed inHiroshima in the capacity of an officer, and many other high rankingofficers. Of the professors of the University, thirty-two were killedor severely injured. Especially hard hit were the soldiers. ThePioneer Regiment was almost entirely wiped out. The barracks were nearthe center of the explosion. 

Thousands of wounded who died later could doubtless have been rescuedhad they received proper treatment and care, but rescue work in acatastrophe of this magnitude had not been envisioned; since the wholecity had been knocked out at a blow, everything which had been preparedfor emergency work was lost, and no preparation had been made forrescue work in the outlying districts. Many of the wounded also diedbecause they had been weakened by under-nourishment and consequentlylacked in strength to recover. Those who had their normal strength andwho received good care slowly healed the burns which had beenoccasioned by the bomb. There were also cases, however, whoseprognosis seemed good who died suddenly. There were also some who hadonly small external wounds who died within a week or later, after aninflammation of the pharynx and oral cavity had taken place. Wethought at first that this was the result of inhalation of thesubstance of the bomb. Later, a commission established the thesis thatgamma rays had been given out at the time of the explosion, followingwhich the internal organs had been injured in a manner resembling thatconsequent upon Roentgen irradiation. This produces a diminution inthe numbers of the white corpuscles. 

Only several cases are known to me personally where individuals who didnot have external burns later died. Father Kleinsorge and FatherCieslik, who were near the center of the explosion, but who did notsuffer burns became quite weak some fourteen days after the explosion. Up to this time small incised wounds had healed normally, butthereafter the wounds which were still unhealed became worse and are todate (in September) still incompletely healed. The attending physiciandiagnosed it as leucopania. There thus seems to be some truth in thestatement that the radiation had some effect on the blood. I am of theopinion, however, that their generally undernourished and weakenedcondition was partly responsible for these findings. It was noisedabout that the ruins of the city emitted deadly rays and that workerswho went there to aid in the clearing died, and that the centraldistrict would be uninhabitable for some time to come. I have mydoubts as to whether such talk is true and myself and others who workedin the ruined area for some hours shortly after the explosion sufferedno such ill effects. 

None of us in those days heard a single outburst against the Americanson the part of the Japanese, nor was there any evidence of a vengefulspirit. The Japanese suffered this terrible blow as part of thefortunes of war ... Something to be borne without complaint. Duringthis, war, I have noted relatively little hatred toward the allies onthe part of the people themselves, although the press has takenoccasion to stir up such feelings. After the victories at thebeginning of the war, the enemy was rather looked down upon, but whenallied offensive gathered momentum and especially after the advent ofthe majestic B-29's, the technical skill of America became an object ofwonder and admiration. 

The following anecdote indicates the spirit of the Japanese: A few daysafter the atomic bombing, the secretary of the University came to usasserting that the Japanese were ready to destroy San Francisco bymeans of an equally effective bomb. It is dubious that he himselfbelieved what he told us. He merely wanted to impress upon usforeigners that the Japanese were capable of similar discoveries. Inhis nationalistic pride, he talked himself into believing this. TheJapanese also intimated that the principle of the new bomb was aJapanese discovery. It was only lack of raw materials, they said, which prevented its construction. In the meantime, the Germans weresaid to have carried the discovery to a further stage and were about toinitiate such bombing. The Americans were reputed to have learned thesecret from the Germans, and they had then brought the bomb to a stageof industrial completion. 

We have discussed among ourselves the ethics of the use of the bomb. Some consider it in the same category as poison gas and were againstits use on a civil population. Others were of the view that in totalwar, as carried on in Japan, there was no difference between civiliansand soldiers, and that the bomb itself was an effective force tendingto end the bloodshed, warning Japan to surrender and thus to avoidtotal destruction. It seems logical to me that he who supports totalwar in principle cannot complain of war against civilians. The crux ofthe matter is whether total war in its present form is justifiable, even when it serves a just purpose. Does it not have material andspiritual evil as its consequences which far exceed whatever good thatmight result? When will our moralists give us a clear answer to thisquestion?