CHAPTER III. 

 INDUCTIVE EPOCH OF HIPPARCHUS. 



Sect. 1. Establishment of the Theory of Epicycles 

 and Eccentrics. 



A LTHOUGH, as we have already seen, at the 

 _t\_ time of Plato, the Idea of Epicycles had been 

 suggested, and the problem of its general applica- 

 tion proposed, and solutions of this problem offered 

 by his followers; we still consider Hipparchus as 

 the real discoverer and founder of that theory; 

 inasmuch as he not only guessed that it might, but 

 showed that it must, account for the phenomena, 

 both as to their nature and as to their quantity. 

 The assertion that " he only discovers who proves," 

 is just ; not only because, until a theory is proved 

 to be the true one, it has no pre-eminence over the 

 numerous other guesses among which it circulates, 

 and above which the proof alone elevates it; but 

 also because he who takes hold of the theory so 

 as to apply calculation to it, possesses it with a 

 distinctness of conception which makes it pecu- 

 liarly his. 



I In order to establish the Theory of Epicycles, it 

 Wis necessary to assign the magnitudes, distances, 





