A HISTORY OF SCIENCE 



of the shadow. But these are mere details, scarcely 

 worthy of mention from our present stand-point. What 

 perhaps is deserving of more attention is the fact that 

 this epoch-making measurement of Eratosthenes may 

 not have been the first one to be made. A passage of 

 Aristotle records that the size of the earth was said to 

 be 400,000 stadia. Some commentators have thought 

 that Aristotle merely referred to the area of the in- 

 habited portion of the earth and not to the circum- 

 ference of the earth itself, but his words seem doubt- 

 fully susceptible of this interpretation ; and if he meant, 

 as his words seem to imply, that philosophers of his 

 day had a tolerably precise idea of the globe, we must 

 assume that this idea was based upon some sort of 

 measurement. The recorded size, 400,000 stadia, is a 

 sufficient approximation to the truth to suggest some- 

 thing more than a mere unsupported guess. Now, 

 since Aristotle died more than fifty years before Era- 

 tosthenes was born, his report as to the alleged size of 

 the earth certainly has a suggestiveness that cannot 

 be overlooked; but it arouses speculations without 

 giving an inkling as to their solution. If Eratosthenes 

 had a precursor as an earth-measurer, no hint or rumor 

 has come down to us that would enable us to guess 

 who that precursor may have been. His personality 

 is as deeply enveloped in the mists of the past as are 

 the personalities of the great prehistoric discoverers. 

 For the purpose of the historian, Eratosthenes must 

 stand as the inventor of the method with which his 

 name is associated, and as the first man of whom 

 we can say with certainty that he measured the 

 size of the earth. Right worthily, then, had the 



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