MARIUS, Simon (1573-1625). Mundus Iovialis anno MDCIX detectus ope perspicill[i] belgici, hoc est quatuor Iovialium planetarum. Nuremberg: Johann Lauer, 1614.

First edition of Marius's report on the satellites of Jupiter, with the earliest known printed illustration of a telescope. Marius was a German astronomer and physician who served at the court of Ansbach. He first acquired a telescope from the Netherlands in 1609 and began to use it to make observations. Through the new instrument, he saw and recorded the moons of Jupiter just one day after Galileo's first sighting of them. Marius had already been involved in a feud with Galileo, after one of his students plagiarized the Paduan astronomer's design for a new proportional compass (although Galileo seems to have recognized at the time that Marius was not involved). As Galileo got his discovery of his “Medicean stars” into print first, he felt entitled to rather viciously accuse Marius of plagiarism in Il Saggiatore after the publication of the present work.

Marius lost the immediate battle of public opinion, tinged also with religious conflict (he was a Lutheran and his use of the Julian calendar led him to incorrectly insist on priority)—but later historians determined that he had indeed independently made the discovery just a day after Galileo, and the moons of Jupiter now bear the names he suggested for them (suggested to him, incidentally, by Kepler). Rare at auction—RBH records only two copies sold. VD17 reports another issue with gathering G reset and the tables set up slightly differently, held only at Wolfenbüttel. Zinner 4474; VD17 12:757402F. See Jay Pasachoff et al., "Simon Marius's Mundus Iovialis: 400th Anniversary in Galileo's Shadow," in Journal for the History of Astronomy 46.2 (2015). Exhibited: "The Heavens Revealed," Chapin Library, Williams College, 2003.

Quarto (182 x 143mm). Woodcut arms on title verso, full-page woodcut author portrait, diagrams (title and final blank rehinged, a few other neat repairs, scattered spots). Modern brown morocco gilt, spine gilt, edges red. Custom box. Provenance: Strasbourg Library (partially erased stamp from title-page verso).