A search for a planet beyond Neptune. By William H. Pickering, assistant professor of astronomy in the Observatory

First edition (only edition), describing "Perturbations at present unexplained, indicating the existence of a trans-neptunian planet having a mass twice that of the Earth" (Annals 75.2 [1913] 240). -- Pluto was discovered in 1930, but Pickering's work suggested a large group of bodies. Recent studies have indeed discovered two groups of asteroid-like objects beyond Neptune. -- -- Collation: Quarto (299 x 247 mm, 11¾ x 9¾ inches): Fifty-six leaves, paginated [109]-162 [163-164 blank], complete as issued. Diagrams, charts, tables. Binding: Printed wrappers, as issued. Condition: Remarkably fine, as shown. (Series: Annals of the astronomical observatory of Harvard College [1855- ] volume 61, part 2.) -- References: W. G. Hoyt "W. H. Pickering's planetary predictions and the discovery of Pluto", Isis 69 (1978) 551-64; P. M. Sadler "William Pickering's search for a planet beyond Neptune", Journal for the history of astronomy 21 (1990) 59-64; Sotheran 2064246n.