These records consist mostly of correspondence between staff at the observing stations and Charles G. Abbot and others on the Observatory staff in Washington, regarding details of operating the stations and personnel problems. Also included are budgets, reports, and other administrative records. See also record unit 46. The stations for which records are included here are Montezuma, on the western slope of the Andes; Mount Saint Katherine, Egypt; Mount Brukkaros, Southwest Africa; Table Mountain, California; and Tyrone, New Mexico.