ASTRONOMY 163 



In agreement with the meteorological opinions which 

 we have just called to mind, there were, concerning the 

 nature and the movement of the heavenly bodies, the 

 eclipses, the shape and position of the earth, very diverse 

 hypotheses of which the following are the principal. 



First of all, to explain the constitution and the 

 movements of the heavenly bodies, Thales and with him 

 Heraclitus considered them as basins which move on the 

 liquid vault of the heavens and in which the dry exha- 

 lations arising from the earth are consumed. Anaxi- 

 mander and probably with him Pythagoras likened the 

 celestial bodies to the felloes of a wheel, which, formed 

 by the compression of the air, encloses an invisible 

 fire ; owing to the compression, openings by which 

 the fire escapes are produced on the periphery of the 

 felloes, which revolve with a uniform movement. 1 

 Anaximenes, on the contrary, declares that the celestial 

 bodies are of an igneous nature and are supported by 

 the air " like thin leaves." 2 Xenophanes considered 

 them to be fiery clouds, similar to St. Elmo's fire, 

 which move in a straight line from east to west. 3 

 Empedocles thought, as we have seen, that the sun was 

 produced by the rays which proceed from the lighted 

 hemisphere and which, after being reflected on the 

 surface of the earth, are concentrated at one point of 

 the crystalline vault. Anaxagoras appears to have 

 been the first to describe the sun, the moon, etc., as 

 fiery stones which are drawn round by the rotation of 

 the ether. 



The explanation of eclipses arises quite naturally 

 from these various ideas. In the cosmology of Thales 

 and Heraclitus, the eclipses, according as they are 

 partial or total, are caused by the inclination or 

 turning over of the luminous face of the basins which 



1 8 Burnet, Aurore, pp. 68 and 124. 

 8 Ibid., p. 31. 

 •Ibid., p. 135. 



