a celebrated physical philosopher of antiquity, was a native of Cnidus, and flourished about the middle of the fourth century B.C. It is chiefly in his quality of astronomer that his name has descended to our times. What particular service he rendered to that science beyond introducing the Egyptian sphere into Greece, and correcting the length of the year, cannot now be ascertained. Of his personal history, it is only known that he studied at Athens under Plato, but being dismissed by that philosopher, passed over into Egypt, where he remained for sixteen months: that he then went to Cyzicum and the Pontus, where he taught physics, and ultimately migrated with a band of pupils to Athens, where he died in the fifty-third year of his age.