b'P ROVING THE P RINCIPLEtists Ross Gunn and Philip Abelson sible, and the job went to the U.S. Groves bought more, placing annualconcluded that the Navy should pursue Army, which created the Manhattan orders amounting to $200 million.the idea. The fission reaction needed no District of its Corps of Engineers. Scientists Gunn and Abelson had nooxygen, which all other fuels need to General Leslie Groves took charge of further access to uranium, so Navyburn. The benefit of such a fuel in a the project and monopolized most of studies of ship propulsion had to pausesubmarine was obvious. The two real- the uranium then in the United States. for the duration of the war. 6ized that the lighter fissionable isotope The Manhattan District bought 1,250of uranium would have to be separated tons of uranium ore from the Belgian The Manhattan Project was a success.from the heavier one in order to create owner of the Shinkolobwe mine for Enrico Fermi and others built thea mass that would fit in a submarine $1.60 a pound. As the war progressed, worlds first nuclear reactor in Chicagoor a bomband begin a chain reaction.They considered how this might bedone. 4As Adolph Hitlers war grew moremenacing in 1939, the scientists inAmerica who had fled Europe grewmore fearful that German scientistsmight produce an atomic bomb. AlbertEinstein wrote a letter to PresidentFranklin Roosevelt urging upon himthe importance of securing a supply ofuranium. The United States has onlypoor ores of uranium in moderatequantities, he wrote. The government should secure a sup-ply of the ore for the United States. Hecontinued:I understand that Germany has actual -ly stopped the sale of uranium from theCzechoslovakian mines which she hastaken over. That she should have takensuch early action might perhaps be No one took photographs when Enrico Fermi and the Met Lab brought Chicago Pile Number One (CP-1) tounderstood on the ground that the son criticality on December 2, 1942. Artist Gary Sheehan shows the cramped quarters in the squash courtof the German undersecretary of state, underneath the stadium at the University of Chicago. Fermi and the others concentrate on instrumentsVon Weizsacker, is attached to the indicating the increasing rate of neutron fission. Three young physicists stationed on the right were the suicideKaiser-Wilhelm-Institut in Berlin, squad, prepared to pour jugs of cadmium-sulfate, a neutron absorber, onto the pile and kill the chain reactionwhere some of the American work on if the control rods didnt work for some reason. The person below the balcony is prepared to operate a controluranium is now being repeated. 5 rod by hand, another precaution. Some employees who participated in the creation of CP-1, not necessarily inthe painting, eventually moved to Idaho to become pioneers at the National Reactor Testing Station.Roosevelt understood the threat andauthorized secret research work tobegin. By 1942, production seemed fea-2 2'