86 A SHORT HISTORY OF SCIENCE 



he considers which hypotheses are in conformity with the phenomena 

 in the heavens. He must accept as his principles from the physicist, 

 that the motions of the stars are simple, uniform, and regular, of 

 which he shows that the revolutions are circular, some along parallels, 

 some along oblique circles. 



This contrast between the physical phenomena and the mathe- 

 matical theory which corresponds with them, without being true 

 or perhaps even possible in all respects, is of continued and in- 

 creasing importance in the history of science, as a larger stock 

 of facts was accumulated and as theories still imperfect were more 

 frequently subjected to critical comparison with observed data, 

 instead of being accepted on purely philosophical or metaphysical 

 grounds. Heraclides is not credited with any conception of 

 orbital or progressive motion of the earth. 



REFERENCES FOR READING 



ALLMAN. Greek Geometry, Chapters III-IX. 



ARISTOTLE. On the Parts of Animals, On Generation, etc. 



BALL. History of Mathematics, Chapter III. 



BUTCHER, S. H. Aspects of the Greek Genius, Chapter I. 



BERRY. History of Astronomy, Chapter II, pp. 26-33. 



DREYER. Planetary System, Chapters III-V. 



FREEMAN, K. E. Schools of Hellas. 



GARRISON, F. H. A History of Medicine. (For Hippocrates of Cos.) 



GOMPERZ. Greek Thinkers, Vol. I. 



Gow. History of Greek Mathematics, Chapter VI, Articles 97-116. 



LEWES, G. H. Aristotle, a Chapter in the History of Science. 



