NEW CONCEPTIONS IN SCIENCE 



Here Aristarchus first attempted to estimate the 

 relative distances of the sun and the moon, and 

 their magnitudes as well. Here lived Eratosthenes, 

 keeper for a time of the great library, a man of 

 the most varied talents, the first great physiog- 

 rapher, and the first to attempt, on correct prin- 

 ciples, a measurement of the size of the earth. 

 As to his computation, it appears to have been 

 not greatly in error roughly 30,000 instead of 

 the correct figure of 25,000 miles in circumfer- 

 ence. It is to be noted that this computation 

 was made on the implicit faith that the earth is 

 round. 



It was, indeed, one of the strangest lapses in his- 

 tory that perfectly clear and just notions respect- 

 ing the form of the earth and its motion round the 

 sun should have grown up among men, have been 

 passed from one century to another, and then dis- 

 appeared from Christendom for a thousand years. 

 These doctrines appear to have been accepted by 

 the earliest astronomers of Alexandria as a part 

 of current knowledge, almost as they are to-day. 

 Pythagoras had taught the motion of the earth in 

 the fifth century B.C. Not this alone, but one of 

 his pupils, Nicetas of Syracuse, clearly taught the 

 motion of the earth on its axis as well. There 

 is a curious passage in Cicero which is worth tran- 

 scribing : 



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