Painting depicting the moment at which the first self-sustaining nuclear chain reaction occurred, on December 2, 1942. The pile was built by a team led by the Italian physicist Enrico Fermi in a squash court under the stands of Chicago University's Stagg Field, and consisted of a complex lattice of bricks of graphite and "slugs" of uranium. At bottom center is George Weil, operating one of the control rods. At top right is the "liquid control squad", armed with buckets of a solution of a cadmium salt (in case of mechanical failure of the control rods). Painting by John Cadell.