George Christopher Eimmart (1638-1705), a native of Ravensburg, was one of Germany’s most famous mathematicians of the seventeenth century.[108] He is reported to have been for some time associated with Erhard Weigel in the University of Jena, where he won distinction for himself in his mathematical and law studies. It was about the year 1658, after the death of his father, that he became especially interested in the art of copper engraving, and in the year 1660 he established himself in this business in the city of Nürnberg. The study of mathematics, however, continued to interest him, and we soon find him giving especial attention to astronomical science, to the construction of astronomical instruments, such as quadrants, sextants, telescopes, astronomical clocks, and celestial spheres. In one of the fortifications of the city he erected a small observatory, in which he carried on his astronomical studies, evincing, as the months passed, much interest in giving practical instruction to many of the young students of the city, among whom may be named Johannes Philipp Würzelbauer, who later was ennobled by Emperor Leopold on account of his scientific attainments, and who at the time of the reception of this honor changed his name to Wurzelbau. Eimmart counted among his friends, with whom he was in constant communication, Leibnitz, Cassini, La Hire, Flamsteed, Hevel, and others. His correspondence with these distinguished men of science, together with his numerous papers relating to his mathematical and astronomical studies, are still preserved in manuscript, filling no less than fifty-seven volumes.[109] In the year 1695 he published a description of an armillary sphere which he had constructed to represent the Copernican system, but this cannot now be located.[110] In the year 1705, the year of his death, he issued a pair of globes, an example of each being now kept in the Museo Astronomico of Rome. These spheres of papier-mâché, each having a diameter of about 30 cm., are supplied each with a base of wood, consisting of four turned columns, which support a horizon circle of wood, on which are the usual engraved concentric circles bearing respectively the names of the principal directions or winds, the names of the zodiacal constellations, with their respective figures, the names of the principal festivals, and names of the saints. They are made to revolve within a graduated meridian circle which is adjusted to move within the horizon circle. The globe balls are covered with engraved gore maps, each consisting of twelve sections cut at the equatorial line and in latitude 80 degrees, the polar areas being covered with a circular disc, having the necessary radius of ten degrees.