8 



HISTORY OF ASTRONOMICAL DISCOVERY. 



celestial bodies its servants, moving in circular orbits, and with uniform velocities, and 



comets simply meteors gene- 

 rated in the terrestrial atmo- 

 sphere. The divine Plato in- 

 deed, the master of Aristotle, 

 is said to have renounced his 

 opinion upon one of these 

 points in his old age, and to 

 have admitted that the centre 

 ought to be appropriated to 

 some more noble object than 

 the earth, or, rather, than ter- 

 restrial substance. It is a 

 plausible conjecture, that the 

 elements of his own system 

 were first suggested to the 

 mind of Copernicus by notices 

 of the opinions of the disciples 

 of Thales and Pythagoras. 

 They won few converts, how- 

 ever, among the Greeks, and 

 in some instances exposed 

 their professors to persecution. 

 The Athenians condemned 

 Anaxagoras to death for his philosophical views, a fate from which he was saved by the 

 interest of Pericles, but he was sentenced to perpetual banishment, and died in an obscure 

 town on the Hellespont. Philolaus also suffered persecution on account of his doctrine of 

 the earth's annual revolution, which so shocked the prejudices of men as to subject him 

 who maintained it to the suspicion of impiety. ^ 



Egypt became the chief seat of astronomical science in the ancient world soon after the 

 age of Aristotle. Alexandria had risen by the delta of the Nile at the command of the 

 conqueror from whom its name is derived, and under the superintendence of the architect 

 who proposed cutting mount Athos into the figure of a man. Upon the death of Alexander 

 it became the capital of one of the kingdoms formed out of the ruins of his empire. The 

 first of the Ptolemies laid the foundation of its celebrated library perhaps the most 

 extensive collection of books ever brought together before the invention of printing. His 

 successor established in connection with it a college for the cultivation of the pure 

 sciences, invited the most accomplished of the Greeks to repair to it, supplied them with 

 whatever instruments could be furnished necessary to their pursuits, and thus arose the 

 Alexandrian school, which received the flattering epithet of Divine, on account of the 

 acquirements of its professors, and the philosophical character of its investigations. It 

 originated a connected series of observations relative to the constitution of the universe. 

 The positions of the fixed stars were determined, the paths of the planets carefully traced, 

 and the solar and lunar inequalities more accurately ascertained. Angular distances 

 were calculated with instruments suitable to the purpose by trigonometrical methods, and, 

 ultimately, the school of Alexandria presented to the world the first system of theoretical 

 astronomy that had ever comprehended an entire plan of the celestial motions. The system 

 we know to be false, and inferior to the Pythagorean notions ; but it had the merit of being 

 founded upon a long and patient observation of phenomena, a principle which finally brought 

 about its own destruction, while the previous theories were the results of pure hypothesis. 



