Taking the place of the boys was an unfamiliar army of young engineers and technicians who were put to work building the 184-inch. Strapped for personnel because of the draft, the Rad Lab’s personnel manager turned to Hollywood. The man he put in charge of fabricating sheet metal for the new cyclotron had previously made fake armor for the movies’ medieval knights.82 For the first time, the magnet yoke of the 60-inch was no longer large enough to accommodate the lab’s research staff in the annual holiday party photograph. “The esprit has perked up considerably with everybody conscious of the necessity to work like the devil,” wrote Kamen to his homesick compatriots in snowy Boston.83
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Early in 1941, as the war news worsened, Lawrence resolved to focus attention upon what seemed the most stubborn roadblocks on the way to a bomb. Separating uranium was highest on his list. Three different methods were then being investigated under NDRC sponsorship: a high-speed centrifuge, diffusion through a permeable membrane, and electromagnetic means. All three relied upon the slight difference in mass between natural uranium, U-238, and its lighter, more fissionable isotope, U-235.
The centrifuge and gaseous diffusion, deemed most promising, were being studied at the University of Virginia and Columbia, respectively. The third method, electromagnetic separation, was the means that Minnesota’s Nier had used to obtain the tiny amount of U-235 available. But the difficulties had been so great that Nier himself dismissed the electromagnetic method as simply not feasible on an industrial scale.84
Lawrence was not so easily discouraged. The apparatus that Nier had used, a mass spectrograph, was mechanically similar to a cyclotron; both required a powerful magnet, a vacuum chamber, and a high-voltage power supply. Lawrence ordered the boys to investigate the feasibility of converting the idled 37-inch into a mass spectrograph for separating uranium.
In early March, Lawrence used the occasion of a Charter Day dinner to urge Conant to “light a fire under” Briggs.85 Visiting MIT in mid-month, Lawrence repeated his concern with the pace of the Uranium Committee to Karl Compton and Alfred Loomis. Lawrence also told of his own plans to convert the 37-inch and to carry out uranium experiments at the Rad Lab. In relaying Lawrence’s message, Compton went so far as to suggest that Bush appoint Lawrence his deputy until the uranium project was as well launched as MIT’s radar lab.
Initially fearful that Lawrence might decide to sit out the war, Bush now worried about Ernest usurping his authority. While insisting that he was “running the show,” Bush named Lawrence to a recently appointed scientific panel, headed by Arthur Compton, which was meant to take things out of Briggs’s hands and bypass the Uranium Committee.86
On May 17, 1941, Compton’s panel submitted its first report. Listed under the category of things that it said fission might make possible were radiological poisons and a new form of propulsion for ships and submarines. But the atomic bomb was a distant third on the list, and nowhere, Bush felt, was there a sense of urgency. Unsatisfied with this first effort, Bush and Conant urged Compton to take another look, adding two engineers to the panel for the purpose.
In the interim, Lawrence had received information that seemed to move the atomic bomb closer to realization. Seaborg and Segrè, having completed their experiments with the mysterious element 94, pronounced it not only fissionable but nearly twice as likely as U-235 to sustain an atomic chain reaction. Ernest immediately telephoned the news to Compton, who passed the word to Bush.
Due to the illness of his daughter, Margaret, Ernest missed the meeting that drafted the second report, which Compton sent to Bush in mid-July. In it, the news about element 94 received curiously little prominence. Indeed, the second report remained substantially unchanged from the first and expressed “primarily the engineers’ point of view,” Compton sniffed.87 Hoping in vain to drum up some enthusiasm for a bomb, Lawrence had appended his own memorandum announcing the fission-ability of element 94.88
Before Bush sent the panel back for a third try, he decided to reorganize the government apparatus that was preparing the country for war. The NDRC was superseded in June 1941 by a larger umbrella organization, the Office of Scientific Research and Development, which reported directly to Roosevelt. Bush took control of OSRD, leaving the NDRC to Conant.89
While he was certainly patriotic, Lawrence’s reasons for belatedly rallying to the colors were not wholly altruistic. The slowly accelerating mobilization had opened his eyes to what could be done in science with government support. Alvarez remembered Ernest returning from meetings at MIT’s Rad Lab with Loomis, bubbling over about the possibilities if one had the money, the resources, and the motivation.90
With German tanks rolling across Russia by July, motivation was soon in abundance. But Bush cannily declined to give construction of the 184-inch a wartime priority as a way of keeping a rein upon Lawrence.91
It was a visitor from overseas that fall who finally spurred Ernest to action. An Australian-born physicist working at the Cavendish, Marc Oliphant had been one of those to challenge Lawrence’s disintegration hypothesis at the Solvay Congress.92 By mid-1941, Oliphant shared the worry of his British colleagues that their American counterparts, Lawrence included, were too sanguine about fission’s peaceful potential and too naive about its prospects for a bomb.93
Weeks earlier, England’s scientists had come to their own conclusions about the feasibility of a uranium weapon. Their top-secret M.A.U.D. report speculated that as little as 22 pounds of U-235 might be required for a bomb. The British also estimated that building the device would take approximately two years and cost $25 million. As with radar’s cavity magnetron, they had
