Gian Domenico Cassini, 1668

CASSINI, Gian Domenico (1625-1712). Ephemerides Bononienses mediceorum syderum ex hypothesis. Bologna: Emilio Maria and Fratelli Manolessi, 1668.

The Haskell Norman copy of the first edition of Cassini’s tables of the movements of the four satellites of Jupiter discovered by Galileo. Lacking sufficiently precise and comprehensive observations, neither Galileo nor his successor at the University of Pisa, Vincenzo Renieri, were able to complete these tables, undertaken in hopes of finding a solution to the problem of determining longitude. Thanks to his friendship with the famous Roman lensmakers G. Campani and E. Divini, Cassini obtained powerful telescopes not available to his predecessors. His ephemerides, published shortly before his move to France, were employed for several decades both by navigators for calculating longitude and by fellow astronomers; Olaus Röhmer, for instance, used them in 1675 for his demonstration that light has a finite speed. They were superseded by more precise tables published by Cassini in Paris in 1693. Norman 411.

Small folio (280 x 195mm). Typographic tables, woodcut initials, type ornament headpiece (minor intermittent spotting). Contemporary limp gilt-paneled vellum. Provenance: Garisenda Antiquariato (bookseller's ticket on front pastedown) – 18th-century manuscript initials "O I S" on front endpaper (partially burnt through) – 19th-century shelfmark label on spine – Haskell F. Norman (1915-1996; bookplate; his sale, Christie's, New York, 15 June 1998, lot 353) – Owen Gingerich (bookplate).