BRAHE, Tycho (1546-1601). Epistolum astronomicarum libri. Uraniborg [Hven]: [at the author's press], 1596.

First edition, first issue, of the scientific correspondence between Tycho Brahe, Landgrave Wilhelm IV of Hesse, and the latter's court astronomer Christopher Rothmann, printed at Brahe's private press in his observatory on the island of Hven, on paper made at the observatory paper mill. Although Brahe had planned to publish a series of volumes containing selections from his vast scientific correspondence, this was the only one to appear. Prince Wilhelm (1532-1592), who had been tutored in his youth by Rumold Mercator, was an important patron of the study of astronomy and a gifted amateur astronomer whose primary concern was improving techniques for astronomical observation. He designed several astronomical instruments, built the first observatory with a revolving dome, and conceived a complete catalogue of the Hessian sky—a vast undertaking for which he obtained, at Brahe's advice, the assistance of the industrious Christoph Rothmann (c.1599-1608), and which was only completed after his death. Brahe had visited Wilhelm at Kassel in 1575 and impressed the Landgrave, whose recommendation may have led King Frederick II of Denmark to offer Brahe the island of Hven as the site for an observatory. The three are not known to have communicated again until the comet of 1585, "which led to an exchange of letters between Tycho in Hven and William IV and Rothmann in Kassel that lasted for six years [...] This correspondence covered all aspects of contemporary astronomy: instruments and methods of observing, the Copernican system (which Rothmann supported against Tycho's system), comets, and auroras" (DSB). Appended is a short description of the Uraniborg observatory—site of "the last of the pre-telescope observations" (Dibner)—illustrated with woodcuts and a map of the island of Hven that would be reused in the 1598 Astronomiae instauratae mechanica. This is one of the first such descriptions of an astronomical observatory, and anticipates the more detailed report of the Mechanica. Very few copies of this first issue remain in private hands. The work is more commonly known through the re-issues of 1601 (Nuremberg: Hulsius, with new title-page) and 1610 (Frankfurt: Tampach, new title-page and some sheets reprinted). Adams B-2653.

Quarto (233 x 165mm). (Marginal stains from washed and treated mildew, repairs to first two quires and colophon, title-page with loss to lower third of leaf with part of imprint and year in facsimile, some short tears and repairs otherwise). Limp vellum (endleaves replaced, old treated mildew stains to vellum); custom box.