the Pupin Physics Laboratories. Fermi recalled that: The pile was built in September 1941 from graphite blocks and tinplate iron cans of uranium oxide. The cans were cubes. When filled with uranium oxide, each weighed about . There were 288 cans in all, and each was surrounded by graphite blocks so the whole would form a cubic lattice structure. A radium-beryllium neutron source was positioned near the bottom. The uranium oxide was heated to remove moisture, and packed into the cans while still hot on a shaking table. The cans were then soldered shut. For a workforce, Pegram secured the services of Columbia's football team. It was the custom at the time for football players to perform odd jobs around the university. They were able to manipulate the heavy cans with ease. The final result was a disappointing k of 0.87. Compton felt that having teams at Columbia University, Princeton University, the University of Chicago and the University of California was creating too much duplication and not enough collaboration, and he resolved to concentrate the work in one location. Nobody wanted to move, and everybody argued in favor of their own location. In January 1942, soon after the United States entered World War II, Compton decided on his own location, the University of Chicago, where he knew he had the unstinting support of university administration. Chicago also had a central location, and scientists, technicians and facilities were more readily available in the Midwest, where war work had not yet taken them away. In contrast, Columbia University was engaged in uranium enrichment efforts under Harold Urey and John Dunning, and was hesitant to add a third secret project. Before leaving for Chicago, Fermi's team made one last attempt to build a working pile at Columbia. Since the cans had absorbed neutrons, they were dispensed with. Instead, the uranium oxide, heated to to dry it out, was pressed into cylindrical holes long and in diameter drilled into the graphite. The entire pile was then canned by soldering sheet metal around it, and the contents heated above the boiling point of water to remove moisture. The result was a k of 0.918. Choice of site In Chicago, Samuel K. Allison had found a suitable location long, wide and high, sunk slightly below ground level, in a space under the stands at Stagg Field originally built as a rackets court. Stagg Field had been