A HISTORY OF SCIENCE 



the chief librarian of Ptolemy Euergetes. He was not 

 merely an astronomer and a geographer, but a poet and 

 grammarian as well. His contemporaries jestingly 

 called him Beta the Second, because he was said 

 through the universality of his attainments to be "a 

 second Plato" in philosophy, "a second Thales" in 

 astronomy, and so on throughout the list. He was also 

 called the "surveyor of the world," in recognition of his 

 services to geography. Hipparchus said of him, per- 

 haps half jestingly, that he had studied astronomy as 

 a geographer and geography as an astronomer. It is 

 not quite clear whether the epigram was meant as 

 compliment or as criticism. Similar phrases have been 

 turned against men of versatile talent in every age. 

 Be that as it may, Eratosthenes passed into history 

 as the father of scientific geography and of scientific 

 chronology ; as the astronomer who first measured the 

 obliquity of the ecliptic ; and as the inventive genius 

 who performed the astounding feat of measuring the 

 size of the globe on which we live at a time when 

 only a relatively small portion of that globe's surface 

 was known to civilized man. It is no discredit to ap- 

 proach astronomy as a geographer and geography as an 

 astonomer if the results are such as these. What Era- 

 tosthenes really did was to approach both astronomy 

 and geography from two seemingly divergent points 

 of attack namely, from the stand-point of the geom- 

 eter and also from that of the poet. Perhaps no man 

 in any age has brought a better combination of ob- 

 serving and imaginative faculties to the aid of science. 

 Nearly all the discoveries of Eratosthenes are asso- 

 ciated with observations of the shadows cast by the 



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