The physicist W.F.G. Swann was a pioneer in high energy physics and the study of cosmic rays. Climbing the academic ranks from the University of Sheffield to the Universities of Minnesota, Chicago, and Yale, Swann was selected as the first director of the Bartol Research Foundation of the Franklin Institute in 1927, and remained there until his retirement in 1959. An able administrator and excellent mentor, he was best known for his popular work on the new physics, The Architecture of the Universe (1934) and for his research on cosmic rays. Avocationally, he was an accomplished cellist and in addition to performing, he helped organize and support the Swarthmore Symphony Orchestra and other local groups. He died at his home in Swarthmore in 1962. The Swann Papers consist of 41 linear feet of correspondence, class notes, lectures, and photographs documenting Swann's career at the Bartol Research Foundation from 1927 until the end of his life. The collection is wide ranging, touching on atmospheric electricity, particle acceleration, atomic bomb defense, atomic energy, electrets, electrodynamics, magnetism, music, quantum theory, radiation, relativity and Einstein, science and civilization, stratospheric flights (by balloon and airplane), thermodynamics, psychic science, and wave mechanics. It is particularly rich for study of the history of cosmic ray research and the Bartol Institute, and for study of the popularization of modern physical sciences.

After receiving his doctorate from Harvard in 1923, the physicist John Clarke Slater did postgraduate work at Cambridge University and on the continent working n quantum theory with both Niels Bohr and Werner Heisenberg. Slater was appointed to the head of the department of physics at MIT in 1930, which he and Karl Compton worked effectively to transform into one of international stature. His own work on the electromagnetic theory of microwaves was fundamental to the development of radar systems. During the Second World War, he was affiliated with the radiation laboratory and after he helped found the solid state and molecular theory group, the interdisciplinary Center for Materials Science and Engineering, the Research Laboratory of Electronics, and the Laboratory for Nuclear Science. After his retirement from MIT in 1966, Slater moved to the University of Florida, remaining active until his death in 1976. The Slater Papers contains a wealth of information on the development of physics at MIT, as well as Slater's post-1966 work at the University of Florida. There are about 133 (7 linear ft.) research notebooks, 1944-1976, and a long series (30 linear ft.) of folders, containing lectures, scientific notes, drafts of manuscripts and papers, correspondence during his collaboration with the Los Alamos Labs, 1966-1970, and extensive correspondence relating to the National Academy of Science. Information about American-Swedish exchange in quantum science is located in the correspondence with Per-Olov Löwdin.