A HISTORY OF SCIENCE 



the periphery of the earth must be the cause of this by 

 having a spherical form. And again, from the appear- 

 ance of the stars it is clear, not only that the earth is 

 round, but that its size is not very large; for when we 

 make a small removal to the south or the north, the 

 circle of the horizon becomes palpably different, so 

 that the stars overhead undergo a great change, and 

 are not the same to those that travel in the north and 

 to the south. For some stars are seen in Egypt or at 

 Cyprus, but are not seen in the countries to the north 

 of these; and the stars that in the north are visible 

 while they make a complete circuit, there undergo a 

 setting. So that from this it is manifest, not only that 

 the form of the earth is round, but also that it is a part 

 of a not very large sphere ; for otherwise the difference 

 would not be so obvious to persons making so small a 

 change of place. Wherefore we may judge that those 

 persons who connect the region in the neighborhood 

 of the pillars of Hercules with that towards India, and 

 who assert that in this way the sea is one, do not as- 

 sert things very improbable. They confirm this con- 

 jecture moreover by the elephants, which are said to 

 be of the same species towards each extreme ; as if this 

 circumstance was a consequence of the conjunction of 

 the extremes. The mathematicians who try to calcu- 

 late the measure of the circumference, make it amount 

 to four hundred thousand stadia; whence we collect 

 that the earth is not only spherical, but is not large 

 compared with the magnitude of the other stars." 



But in giving full meed of praise to Aristotle for the 

 promulgation of this doctrine of the sphericity of the 



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