These papers document Greeley's career and experiences during his tours of duty at the solar radiation observing stations, usually located on high-elevation barren mountaintops in desert regions. These materials consist primarily of correspondence, diaries, notes, manuscripts, photographs, and personal documents. The correspondence includes incoming and outgoing official correspondence, 1939-1955, mostly with Charles G. Abbot and Loyal B. Aldrich, concerning daily activities, equipment, station buildings, and financial reports; correspondence to family members, 1923-1952, in which Greeley described his experiences and travels; correspondence from Charles G. Abbot, 1964-1969, mostly concerning his activities and news of former SAO staff; and correspondence from researchers interested in the study of the SAO's solar constant program, 1977-1978. The manuscripts consist of Greeley's unpublished autobiography, "Following the Sun" (undated typed copies) and excerpts of correspondence to members of his family in which he described his daily life and experience at the stations and on travel, 1920-1936; and Douglas V. Hoyt's study, "Smithsonian Astrophysical Observatory Solar Constant Program", 1978, and a published version, 1979. The diaries were written mainly by Greeley's wife, Olive A. Greeley, who also served as bolometer assistant at Mount Montezuma, 1943-1946. The entries document day-to-day activities at the various stations, mostly at Mount Montezuma, Miami, and Table Mountain, and entries by Greeley concerning traveling expense accounts, 1938, and 1940-1941. The photographs consist of scenes taken by Greeley during his tours of duty. Also included in this collection are personal documents such as passports, automobile registrations, internal identification cards (Chile), and ship passenger lists; mathematical notes; instrument operation instructions; methods of data computation, issued by Abbot; newspaper articles about the Greeleys and the SAO's solar radiation observatories; radio interviews and speeches by the Greeleys about their experiences, and about Charles G. Abbot; and two 8mm motion pictures, one a black and white film, showing a panoramic view of the Sinai from Mount Zebir Gemir, circa 1934, and one in color showing a segment of the Rose Bowl Parade and snow scenes at Table Mountain, 1949.