224 THE GREEK ASTRONOMY. 



no merit : they are remarkable as showing how 

 the persuasion of the universality of law, and the 

 belief of the probability of its discovery by man, 

 grow up in men's minds, when speculative know- 

 ledge becomes a prominent object of attention. 



An important practical application of astrono- 

 mical knowledge was made by Julius Caesar, in his 

 correction of the calendar, which we have already 

 noticed: and this was strictly due to the Alexan- 

 drian School : Sosigenes, an astronomer belonging 

 to that school, came from Egypt to Rome for the 

 purpose. 



Sect. 5. Measures of the Earth. 



THERE were, as we have said, few attempts made, 

 at the period of which we are speaking, to improve 

 the accuracy of any of the determinations of the 

 early Alexandrian astronomers. One question na- 

 turally excited much attention at all times, the 

 magnitude of the earth, its figure being universally 

 acknowledged to be a globe. The Chaldeans, at 

 an earlier period, had asserted that a man, walking 

 without stopping, might go round the circuit of 

 the earth in a year; but this might be a mere 

 fancy, or a mere guess. The attempt of Eratos- 

 thenes to decide this question went upon principles 

 entirely correct. Syene was situated on the tropic ; 

 for there, on the day of the solstice, at noon, ob- 

 jects cast no shadow ; and a well was enlightened 

 to the bottom by the sun's rays. At Alexandria, 

 on the same day, the sun was, at noon, distant 



