Memoirs of the Lowell Observatory: Memoir on a trans-Neptunian Planet and Memoir on Saturn's Rings [Two Volumes]

Lynn, MA. 1915: Thos. P. Nichols & Son Co. First Edition. Quarto. In two Volumes. Lowell was an American astronomer who predicted the existence of a planet beyond the orbit of Neptune. He published a series of "Memoirs of the Lowell Observatory" containing theoretical researches of his personal studies of a "Trans-Neptuneian Planet" and of the structure of "Saturn's Rings". In volume one he attributed certain irregularities to the action of an unseen planet beyond Neptune and calculated its probable position. In 1905 he organized a systematic search for the planet by the staff of his observatory, and in 1915 he published his Memoir on a Trans-Neptunian Planet. Fourteen years after his death the search culminated in the discovery of Pluto. Volume two contains his observations and calculations of Saturn's rotation and the density of its rings. Volume 1, No. 1: 105pp. with nine plates (two double-page) situated at the rear, bound in original printed wraps with stripes (off-setting from cardboard box but not present) . Volume 1, No. 2: 22pp. 2 plates. Bound in original printed wraps. Both volumes are in absolute fine condition save for the stripes. No names, tears or loss of any kind. Quite rare to have both copies.