Work at Caltech during the 1930s; when the Cockcroft-Walton paper appeared in 1932, he shifted from X-ray work to nuclear work. Development of ion sources and detection equipment, the building of a second tube at the High Voltage Laboratory, old tube is used in cancer therapy. Begins a systematic study of energy levels in light nuclei after discovery of artificial radioactivity. Interest in nuclear physics in Caltech. Nuclear work during the war, and the increase in level of support by Office of Naval Research (ONR) after the war. Also prominently mentioned are: Carl David Anderson, Robert Fox Bacher, Willard Bennett, Hans Albrecht Bethe, Niels Henrik David Bohr, Ira Sprague Bowen, Horace Richard Crane, Robert Andrews Millikan, Seeley Mudd, J. Robert Oppenheimer, Ernest Rutherford, Merle Antony Tuve; Conference on Theoretical Physics (1934 : London, England), Mount Wilson Observatory, Southern California Edison Company, University of California, Berkeley.