68] 



The Celestial Spheres 



supposed changes in the obliquity of the ecliptic. A few 

 writers invented a larger number. Outside these spheres 

 mediaeval thought usually placed the Empyrean or Heaven. 

 The accompanying diagram illustrates the whole arrange- 

 ment. 



C3l 



FIG. 36. The celestial spheres. From Apian's Costnograplita. 



These spheres, which were almost entirely fanciful and 

 in no serious way even professed to account for the details 

 of the celestial motions, are of course quite different from 

 the circles known as deferents and epicycles, which Hippar- 

 chus and Ptolemy used. These were mere geometrical 



