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.

One of the seminal figures in the emergence of the Modern or Neo-Darwinian Synthesis during the mid-twentieth century, George Gaylord Simpson (1902-1984) helped define the unique contribution made by vertebrate paleontology to the life sciences. A specialist in Mesozoic and early Cenozoic mammals, Simpson's contributions to the fusion of Darwinian natural selection and Mendelian genetics were both empirical and theoretical, culminating in his major works Tempo and Mode in Evolution and The Meaning of Evolution. From his posts at the American Museum of Natural History (1927-1959), Columbia University (1945-1959), Harvard (1959-1967), and the University of Arizona (1967-1984), Simpson became one of the most influential paleontologists of the century, helped in part by his ability to write successfully for both a technical, professional audience and a popular audience. The Simpson Papers include a comprehensive assemblage of professional and personal correspondence, reflecting nealy all phases of Simpson's career. Written with charm, wit, and a sense of literary style, the correspondence touches on all aspects of modern paleontology, providing an important perspective on the emergence of contemporary evolutionary theory, biogeography, systematic theory and methodology, the relationship of science and religion, and creationism, as well as more general issues in scientific epistemology and social and political issues. The collection also includes autobiographical data and writings, lectures, class notes and papers, research data, material on his scientific expeditions (diaries in carbon form, photos, notes, etc.), publication material (he was author of some 800 publications), extensive photographic material, diplomas, and medals.