228 THE GREEK ASTRONOMY. 



of the other calculations which are requisite, in 

 order to deduce the consequences of this theory, 

 the work is a splendid and lasting monument of 

 diligence, skill and judgment. Indeed, all the other 

 astronomical works of the ancients hardly add any- 

 thing whatever to the information we obtain from 

 the Almagest ; and the knowledge which the 

 student possesses of the ancient astronomy must 

 depend mainly upon his acquaintance with Pto- 

 lemy. Among other merits, Ptolemy has that of 

 giving us a very copious account of the manner in 

 which Hipparchus established the main points of 

 his theories; an account the more agreeable, in 

 consequence of the admiration and enthusiasm with 

 which this author everywhere speaks of the great 

 master of the astronomical school. 



In our present survey of the writings of Pto- 

 lemy, we are concerned less with his exposition 

 of what had been done before him, than with 

 his own original labours. In most of the branches 

 of the subject, he gave additional exactness to 

 what Hipparchus had done ; but our main business, 

 at present, is with those parts of the Almagest 

 which contain new steps in the application of the 

 Hipparchian hypothesis. There are two such cases, 

 both very remarkable, that of the moon's Elec- 

 tion, and that of the Planetary Motions. 



The law of the moon's anomaly, that is, of the 

 leading and obvious inequality of her motion, could 

 be represented, as we have seen, either by an 



