As philosopher and principal mathematician to the grand duke of Tuscany, Galileo now took up his residence at Florence, with a salary of 1000 florins. No official duties, excepting that of lecturing occasionally to sovereign princes, were attached to this appointment; and it was expressly stipulated that he should enjoy the most perfect leisure to complete his treatises on the constitution of the universe, on mechanics, and on local motion. The resignation of his professorship at Padua, which necessarily followed his new appointment, created much dissatisfaction in that university: but though many of his former friends refused at first to hold any communication with him, this feeling gradually subsided; and the Venetian senate at last appreciated the views, as well as the powerful motives, which induced a stranger to accept of promotion in his native land. While Galileo was enjoying the reward and the fame of his great discovery, a new species of enmity was roused against them. Simon Mayer, an astronomer of no character, pretended that he had discovered the satellites of Jupiter before Galileo, and that his first observation was made on the 29th of December, 1609. Other astronomers announced the discovery of new satellites: Scheiner reckoned five, Rheita nine, and others found even so many as twelve: these satellites, however, were found to be only fixed stars. The names of _Vladislavian, Agrippine, Uranodavian_, and _Ferdinandotertian_, which were hastily given to these common telescopic stars, soon disappeared from the page of science, and even the splendid telescopes of modern times have not been able to add another gem to the diadem of Jupiter.