RICHARD A. PROCTOR (1837-88) SIGNED SLIP, “Believe me/Very sincerely yours/Rich. A. Proctor”, on a slip 4 x 2.25, by the English astronomer best remembered for having produced the first map of Mars. His first book Saturn and its System was favorably received by astronomers but did not sell well. This convinced him that the general public was not interested in works requiring arduous study, so he cultivated a more popular style and his books had a wide influence in familiarizing the public with the main facts of astronomy. His literary standing improved and he became a regular contributor to many publications and followed with a long series of popular books. He founded Knowledge a popular magazine of science, which had a considerable circulation. He was elected a fellow of the Royal Astronomical Society and contributed 83 separate papers to its Monthly Notices. The handwritten slip is in fine condition, with minor age toning.