LIED re l CT the k' oTic pr t' A f '2' 01 19 clis coot n Wq Kf yrohib tcd Z t w a gel i ° 4H' t1L LL tL J' J t I d N 61-4 - Lt u ao 0 d-i i V 6 2 I c -- tt i ___a -6t -Md oJ t-'L' pr O t-- C --j L J J -17 o-n T' Vl Y -j L p - A - ice If ill o vdv izv- A41-1 64 S 1 The item identified below has been withdrawn from this file In the review of this file this item was removed because access to it is restricted Restrictions on records in the National Archives are stated in general and specific record group restriction statements which are available for examination because it contains The item identified above has been withdrawn Notes on the “Trinity” Test Held at Alamogordo Bombing Range 125 miles south east of Alburquerque 5 30 a m Monday July 16 V Bush Gen Groves and J B C arrived at the Base Camp located 10 miles from the bomb at about 8 p m Sunday evening After dinner at the mess and some brief explanation by J R Oppenheimer R C Tolman G Kistiakowsky and I I Rabbi sic in very informal conversation we went to bed The atmosphere was a bit tense as might be expected but everyone felt confident that the bomb would explode The pool on the size of the explosion ran from 0 a few pessimists to 18 000 Rabbi sic and perhaps someone at 50 000 several words censored My own figure was 4400 tons of T N T but I never signed up It was a bad night though the weather forecast had been favorable for a clear early morning with light winds the desired condition From about 10 30 to 1 a m it blew very hard thus preventing sleep in our tent and promising a postponement of the Test Then it poured for about an hour At 1 a m General Groves arose and went out to the forward barricade with the key personnel There were two forward bases located 10 000 yds N S of the bomb The wiring from this point to the test and to the camp was fantastic in their extent The instrumentation of the test included a vast array of equipment At 3 15 a m the rain having just ceased Rabbi sic came into our tent V Bush and JBC and said that there had been much talk of a postponement because of the weather but reports indicated a 75% chance of going through with it but at 5 a m instead of the scheduled 4 a m We got up dressed and drank some coffee about 4 a m and wandered around The sky was still overcast It had not rained however at the zero point the bomb and the lines were O K Word then came through about 4 30 that 5 10 would be the time About 5 p m sic — a m or a little after word came that the firing would occur at 5 30 Shortly after General Groves came back to the forward area We prepared to view the scene from a slight rise near the camp Col S tafford Warren was in charge of health Tolman Rabbi sic Gen Groves J B C were more or less together It was agreed that because of the expected or hoped bright flash and the ultra violet light no ozone to absorb it it would be advisable to lie flat and look away at the start then look through the heavy dark glass At 5 20 the sirens blew the 10 min signal then another at 5 25 and I think another 2 mins before We lay belly down facing 180 degrees away from the spot on the tarpaulin I kept my eyes open looking at the horizon opposite the spot It was beginning to be light but the general sky was still dark particularly in the general direction I was looking Through the loud speaker nearby I heard Samuel Allison counting the seconds minus 45 minus 40 minus 30 minus 20 minus 10 The firing was done by some kind of timing devices started at minus 45 sec These were long seconds Then came a burst of white light that seemed to fill the sky and seemed to last for seconds I had expected a relatively quick and bright flash The enormity of the light and its length quite stunned me My instantaneous reaction was that something had gone wrong and that the thermal nuclear transformation of the atmosphere once discussed as a possibility and jokingly referred to a few minutes earlier had actually occurred Slightly blinded for a second I turned on my back as quickly as possible and raising my head slightly could see the “fire” through the dark glass At that stage it looked like an enormous pyrotechnic display with great boiling of luminous vapors some spots being brighter than others A picture from memory is as seen through heavy dark glass Very shortly this view began to fade and without thinking the glass was lowered and the scene viewed with the naked eye The ball of gas was enlarging rapidly and turning into a mushroom It was reddish purple and against the early dawn very luminous though I instantly thought of it as colored somewhere Then someone shouted watch out for the detonation wave this was 40 sec after zero time Still on my back I heard the detonation but was not in a position to notice any blast there was relatively little felt here The sound was less loud or startling than I expected but the shock of sensory impression was still dominant in my mind Then I got up and watched the spread of the colored luminous gas There was two secondary explosions after the detonation wave reached us or just before The cloud billowed upward when these occurred and very soon thereafter billowed up as would an oil fire the color became less and the whole looked more like a unintelligible fire though on an enormous scale The column of smoke then began to spread and took on a Z form which persisted for some time The spectacular part must have been confined to about 90 seconds The phases observed by the eye were as follows from memory As soon as I had lowered my dark glass and before rising I shook Gen Groves hand who said “Well I guess there is something in nucleonics after all ” Tolman as we rose said that is something very different from the 100-ton TNT shot “entirely differently there is no question but what they got a nuclear reaction ” Then several people began saying “Very much larger than expected Rabbi sic said it was 15 000 Tons equivalent at least ” At about 60 sec as the cloud billowed up the assembled group including many MPs’ gave out a spontaneous cheer Then the reports began to come in Oppenheimer arrived in about 5 or 10 minutes and said the equivalent was 2100 Tons which was greeted with great skepticism It afterwards turned out he had made an error in converting the first blast measurement and the figure showed 7 000 tons The most exciting news was that the steel tower over “Jumbo” 800 yards away had disappeared This was reported by someone with a telescope and verified by all This was unexpected and showed a very much more powerful effect than expected Before we left at noon the best estimate seemed to be between 10 000–15 000 though Rabbi sic maintain 18 000 would yet prove right Careful exploration of the crater showed 1200 yards again more than expected The toxicity problem proved not serious Thought at 10 000 yards North evacuated in a hurry as their meter went off the scale almost at once and the cloud of smoke seemed to chase them they declared All evacuation was by car of course One man at the Camp Site who looked at the explosion without dark eye glasses got a bad eye burn and was given morphine the prognosis was that he would not lose his sight G Kistiakowsky all frowns came in to report that the shock wave had knocked him down as he stood outside the barricade at 10 000 S There were reports of two others being knocked down at the same spot My first impression remains the most vivid a cosmic phenomena like an eclipse The whole sky suddenly full of white light like the end of the world Perhaps my impression was only premature on a time scale of years J B Conant Washington D C July 17 1945 4 30 p m First version of transcript prepared by Professor James Hershberg George Washington University with later edits by Alex Wellerstein Stevens Institute of Technology and William Burr National Security Archive