Dutch astronomer (1901-1995) who served as director of Swarthmore College's Sproul Observatory from 1937 to 1972, specializing in the study of parallax and proper motions of stars. He came to public attention in the 1960s when he announced that Barnard's star had a planetary system based on observed 'wobbles' in its motion, an assertion now known to be false. Collection of correspondence between Peter van der Kamp and Cambridge astronomer Arthur Beer, comprising 41 letters by van der Kamp (33 TLSs and eight ALSs), along with a multitude of Beer's retained carbon copies and drafts, dating from 1953 to 1974. Van der Kamp writes concerning his contributions to Beer’s ‘Vistas in Astronomy' series, arrangements for visits and lectures, and joint projects. In overall fine condition.