ASTRONOMY. 333 



round, that we had antipodes ; and that the moon reflected the rays 

 of the sun ; that the stars were worlds, containing earth, air, and 

 ether ; that the moon was inhabited like the earth ; and that the 

 comets were a kind of wandering stars, disappearing in the superior 

 parts of their orbits, and becoming visible only in the lower parts of 

 them. The white colour of the milky-way he ascribed to the bright- 

 ness of a great number of small stars ; and he supposed the distances 

 of the moon and planets from the earth to be in certain harmonic pro- 

 portion to one another. He is said also to have exhibited the oblique 

 course of the sun in the ecliptic and the tropical circles, by means of 

 an artificial sphere ; and he first taught that the planet Venus is both 

 the evening and morning star. This philosopher is said to have been 

 taken prisoner by Cambyses, and thus to have become acquainted 

 with all the mysteries of the Persian magi ; after which he settled at 

 Crotona in Italy, and founded the Italian sect. 



About 440 years before the Christian era, Philolaus, a celebrated Phiioiaus. 

 Pythagorean, asserted the annual motion of the earth round the sun ; B ' c ' 441 

 and soon after Hicetas, a Syracusan, taught its diurnal motion on its 

 own axis. About this time also flourished Meton and Euctemon at 

 Athens, who took an exact observation of the summer solstice 432 

 years before Christ ; which is the oldest observation of the kind we 

 have, excepting some doubtful ones of the Chinese. Meton is said to 

 have composed a cycle of nineteen years, which still bears his name ; 

 and he marked the risings and settings of the stars, and what seasons 

 they pointed out : in all of which he was assisted by his companion 

 Euctemon. The science, however, was obscured by Plato and Aris- 

 totle, who embraced the system afterwards called the ' Ptolemaic,' 

 which places the earth in the centre of the universe. 



After Philolaus, the next astronomer we meet with of great repu- Eudoxus. 

 tation is Eudoxus, who flourished 370 B.C. He was a contemporary B - c - 370 - 

 with Aristotle though considerably older, and is greatly celebrated for 

 his skill in this science. He is said to have been the first to apply 

 geometry to astronomy, and is supposed to be the inventor of many of 

 the propositions attributed to Euclid. Having travelled into Egypt 

 in the early part of his life, he obtained a recommendation' from Age- 

 silaus to Nectanebus, king of Egypt, and by his means got access to 

 the priests, who were then held to have great knowledge of astronomy ; 

 after which he taught in Asia and Italy. Seneca tells us, that he 

 brought the knowledge of astronomy, i. e., of the planetary motions, 

 from Egypt into Greece ; and according to Archimedes, his opinion was, 

 that the diameter of the sun was nine times that of the moon. He was 

 also acquainted with the method of drawing a sun-dial on a plane. 



Soon after Eudoxus, we meet with Calippus, whose system of the Caiippus. 

 celestial sphere is mentioned by Aristotle ; but he is better known for B ' c< 33U- 

 a period of seventy-six years, containing four corrected Metonic periods, 

 and which had its beginning at the summer solstice, in the year 330 

 B. c. And it was about this time, or rather earlier, that the Greeks 



