we could not see how, in actual fact, we could get into trouble. Then I asked him, “And what do you think about it?” There in the dark Bob thought for a moment, then said, “I'll take a second bottle of whiskey.”
Rabi, the real mystic among them, spent the evening playing poker.
Bainbridge managed a little sleep. He headed the Arming Party charged with arming the bomb. He was due at Zero by 11 p.m. to prepare the shot. An MP sergeant woke him at ten; he picked up Kistiakowsky and Joseph McKibben, the tall, lanky Missouri-born physicist responsible for running the countdown, and assembled with Hubbard and his crew and two security men. “On the way in,” Bainbridge remembers, “I stopped at S 10,000 and locked the main sequence timing switches. Pocketing the key I returned to the car and continued to Point Zero.” A young Harvard physicist, Donald Hornig, was busy in the tower. He had designed the 500-pound X-unit of high- voltage capacitors that fired Fat Man's multiple detonators with microsecond simultaneity, a crucial Luis Alvarez invention, and now was disconnecting the unit Bainbridge's crews had used for practice runs and connecting the new unit reserved for the shot. In static test this Fat Man would be fired through cables from the S-10000 control bunker; the one to be shipped to Tinian, self-contained, would carry onboard batteries. Cables or batteries would charge the X-unit and on command it would discharge its capacitors to the detonators, vaporizing wires imbedded in the explosive blocks to start shock waves to set off the HE. “Soon after our arrival,” says Bainbridge, “Hornig completed his work and returned to S 10,000. Hornig was the last man to leave the top of the tower.”
Hubbard operated a portable weather station at the tower; to measure wind speed and direction the two sergeants who worked with him inflated and released helium balloons. At eleven o'clock he found the wind blowing across Zero toward N-10000. At midnight the Gulf air mass had thickened to 17,000 feet and arranged two inversions — cooler air above warmer — within its layered depths that might loop the radioactive Trinity column back down to the ground directly below.
To an observer traveling toward the desert from Los Alamos “the night was dark with black clouds, and not a star could be seen.”
Thunderstorms began lashing the Jornada at about 0200 hours on July 16, drenching Base Camp and S- 10000. “It was raining cats and dogs, lightning and thunder,” Rabi remembers. “[We were] really scared [that] this object there in the tower might be set off accidentally. So you can imagine the strain on Oppenheimer.” Winds gusted to thirty miles an hour. Hubbard hung on at Zero for last-minute readings — only misting drizzle had yet reached the tower area — and arrived eight minutes late for the 0200 weather conference at Base Camp, to find Oppenheimer waiting for him outside the weather center there. Hubbard told him they would have to scrub 0400 but should be able to shoot between 0500 and 0600. Oppenheimer looked relieved.
Inside they found an agitated Groves waiting with his advisers. “What the hell is wrong with the weather?” the general greeted his forecaster. Hubbard took the opportunity to repeat that he had never liked July 16. Groves demanded to know when the storm would pass. Hubbard explained its dynamics: a tropical air mass, night rain. Afternoon thunderstorms took their energy from the heating of the earth and collapsed at sunset; this one, contrariwise, would collapse at dawn. Groves growled that he wanted a specific time, not an explanation. I'm giving you both, Hubbard rejoined. He thought Groves was ready to cancel the shot, which seems unlikely given the pressure from Potsdam. He told Groves he could postpone if he wanted but the weather would relent at dawn.
Oppenheimer applied himself to soothe his bulky comrade. Hubbard was the best man around, he insisted, and they ought to trust his forecast. The others at the meeting — Tolman and two Army meteorologists, one more than before — agreed. Groves relented. “You'd better be right on this,” he threatened Hubbard, “or I will hang you.” He ordered the meteorologist to sign his forecast and set the shot for 0530. Then he went off to roust the governor of New Mexico out of bed to the telephone to warn him he might have to declare martial law.
Bainbridge at Zero was less concerned with local effects than with distant, even though he had personally locked open the circuits that communicated with the shelters, “Sporadic rain was a disturbing factor,” he recalls. “… We had none of the lightning reported by those at the Base Camp about 16,000 yards away or at S 10,000, but it made interesting conversation as many of the wires from N, S, W 10,000 ended at the tower.” About 0330 a gust of wind at Base Camp collapsed Vannevar Bush's tent; he found his way to the mess hall, where from 0345 the cooks began serving a breakfast of powdered eggs, coffee and French toast.
The gods sent Emilio Segre happier amusement. He had distracted himself through the evening with Andr6 Gide's
Hubbard departed Base Camp at 0315 for S-10000. The rain had moved on. He telephoned Zero; one of his men there said the clouds were opening and a few stars shone. By 0400 the wind was shifting toward the southwest, away from the shelters. The meteorologist prepared his final forecast at S-10000. He called Bainbridge at 0440. “Hubbard gave me a complete weather report,” the Trinity director recalls, “and a prediction that at 5:30 a.m. the weather at Point Zero would be possible but not ideal. We would have preferred no inversion layer at 17,000 feet but not at the expense of waiting over half a day. I called Oppenheimer and General Farrell to get their agreement that 5:30 a.m. would be T = 0.” Hubbard, Bainbridge, Oppenheimer and Farrell each had veto over the shot. They all agreed. Trinity would fire at 0530 hours July 16, 1945 — just before dawn.
Bainbridge had arranged to report each step of the final arming process to S-10000 in case anything went wrong. “I drove McKibben to W 900 so that he could throw the timing and sequence switches there while I checked off his list.” Back at Zero Bainbridge called in the next step “and threw the special arming switch which was not on McKibben's lines. Until this switch was closed the bonib could not be detonated from S 10,000. The final task was to switch on a string of lights on the ground which were to serve as an ‘aiming point’ for a B-29 practice bombing run. The Air Force wanted to know what the blast effects would be like on a plane 30,000 feet up and some miles away… After turning on the lights, I returned to my car and drove to S 10,000.” Kistiakowsky, McKibben and the security guards rode with him. They were the last to leave the site. Behind them searchlight beams converged on the tower.
The Arming Party arrived at S-10000, the earth-sheltered concrete control bunker, at about 0508. Hubbard gave Bainbridge his signed forecast. “I unlocked the master switches,” Bainbridge concludes, “and McKibben started the timing sequence at -20 minutes, 5:09:45 a.m.” Oppenheimer would watch the shot from S-10000, as would Farrell, Donald Hornig and Samuel Allison. With the beginning of the final countdown Groves left by jeep for Base Camp. For protection against common disaster he wanted to be physically separated from Farrell and Oppenheimer.
Busloads of visitors from Los Alamos and beyond had begun arriving at Compania Hill, the viewing site twenty miles northwest of Zero, at 0200. Ernest Lawrence was there, Hans Bethe, Teller, Serber, Edwin McMillan, James Chadwick come to see what his neutron was capable of and a crowd of other men, including Trinity staff no longer needed down on the plain. “With the darkness and the waiting in the chill of the desert the tension became almost unendurable,” one of them remembers. The shortwave radio requisitioned to advise them of the schedule refused to work until after Allison began broadcasting the countdown. Richard Feynman, a future Nobel laureate who had entered physics as an adolescent via radio tinkering, tinkered the radio to life. Men began moving into position. “We were told to lie down on the sand,” Teller protests, “turn our faces away from the blast, and bury our heads in our arms. No one complied. We were determined to look the beast in the eye.” The radio went dead again and they were left to watch for the warning rockets to be fired from S-10000. “I wouldn't turn away… but having made all those calculations, I thought the blast might be rather bigger than expected. So I put on some suntan lotion.” Teller passed the lotion around and the strange prophylaxis disturbed one observer: “It was an eerie sight to see a number of our highest-ranking scientists seriously rubbing sunburn lotion on their faces and hands in the pitch-blackness of the night, twenty miles from the expected flash.”
The countdown continued at S-10000. At 0525 a green Very rocket went up. That signaled a short wail of the siren at Base Camp. Shallow trenches had been bulldozed below the south rim of the Base Camp reservoir for protection and since these men watched ten miles closer to Zero than the crowd on Compania Hill they planned to use them. Rabi lay down next to Kenneth Greisen, a Cornell physicist, facing south away from Zero. Greisen remembers that he was “personally nervous, for my group had prepared and installed the detonators, and if the shot turned out to be a dud, it might possibly be our fault.” Groves found refuge between Bush and Conant, thinking “only of what I would do if, when the countdown got to zero, nothing happened.” Victor Weisskopf remembers that “groups of observers had arranged small wooden sticks at a distance of 10 yds from our observation place in order
