Biographical material includes Fowler's personal file from the Department of Physics at the University of Bristol and other documents relating to his career; honors and awards including his Royal Society Fellowship and Research Professorship; also historical material relating to C. F. Powell. There are substantial lecture notes from the undergraduate studies of Fowler and Rosemary Brown from the Bristol Physics Department in the 1940s, as well as other University of Bristol materials from Fowler's tenure there. Largest amount of records are from the numerous microscope observers, scanners, balloon makers and technicians employed by the H. H. Wills Laboratory in cosmic ray research. Includes some material relating to balloon flights for cosmic ray studies arranged chronologically; most dates from the 1960s, covering various balloon flight launches worldwide, and includes correspondence and papers relating to arrangements for flights, balloon technical specifications, flight plans, proposals, and analysis of results. Other research interests documented include pi-mesons in cancer treatment, magnetic monopoles, the heavy primary cosmic ray detector for the Ariel 6 satellite, and the assessment of the radioactive fallout from the Ukrainian nuclear plant Chernobyl, ten years after its explosion. Materials relating to publications are arranged chronologically, 1947-circa 1996, and includes offprints, drafts, figures and correspondence. There are records of physics teaching at Bristol in the 1950s-1960s, and Fowler's public and invited lectures, principally on cosmic rays, 1964-1996. Visits and conferences are documented for the period 1956-1993. Involvement with seventeen UK and international organizations is covered, in particular the International Union of Pure and Applied Physics, the Joint MRC/NRPB Committee on Radiological Protection (1983-1992), the Royal Astronomical Society, the Royal Society, and the Science and Engineering Research Council. Correspondence is arranged alphabetically following Fowler's original order; correspondents are mainly scientific colleagues and historians of science, but there are no extended exchanges.