184 THE GREEK ASTRONOMY. 



The Sun's Eccentric. When Hipparchus had 

 clearly conceived these hypotheses, as possible ways 

 of accounting for the sun's motion, the task which he 

 had to perform, in order to show that they deserved 

 to be adopted, was to assign a place to the Perigee, 

 a magnitude to the Eccentricity, and an Epoch at 

 which the sun was at the perigee ; and to show that, 

 in this way, he had produced a true representation 

 of the motions of the sun. This, accordingly, he did ; 

 and having thus determined, with considerable ex- 

 actness, both the law of the solar irregularities, and 

 the numbers on which their amount depends, he 

 was able to assign the motions and places of the 

 sun for any moment of future time with correspond- 

 ing exactness ; he was able, in short, to construct 

 Solar Tables, by means of which the sun's place 

 with respect to the stars could be correctly found 

 at any time. These tables (as they are given by 

 Ptolemy 1 ,) give the Anomaly, or inequality of the 

 sun's motion; and this they exhibit by means of the 

 Prosthapheresis, the quantity which, at any distance 

 of the sun from the Apogee, it is requisite to add 

 to or subtract from the arc, which he would have 

 described if his motion had been equable. 



The reader might perhaps expect that the calcu- 

 lations which thus exhibited the motions of the sun 

 for an indefinite future period must depend upon 

 a considerable number of observations made at all 

 \easons of the year. That, however, was not the 

 1 Syntax. 1. iii. 



