THE CONTINUITY OF SCIENCE 45 



of Greek culture. On the death of Alexander the 

 Great, Egypt was ruled by one of his generals, 

 Ptolemy, who assumed the title of king. This mon- 

 arch, though often engaged in war, found time to 

 encourage learning, and drew to his capital scholars 

 and philosophers from Greece and other countries. 

 He wrote himself a history of Alexander's cam- 

 paigns, and instituted the famous library of Alexan- 

 dria. This was greatly developed (and supplemented 

 with schools of science and an observatory) by his 

 son Ptolemy Philadelphus, a prince distinguished by 

 his zeal in promoting the good of the human species. 

 He collected vast numbers of manuscripts, had 

 strange animals brought from distant lands to Alex- 

 andria, and otherwise promoted scientific research. 

 This movement was continued under Ptolemy III 

 (246-221 B.C.). 



Something has already been said of the early as- 

 tronomers and mathematicians of Alexandria. The 

 scientific movement of the later Alexandrian period 

 found its consummation in the geographer, astrono- 

 mer, and mathematician Claudius Ptolemy (not to 

 be confused with the rulers of that name). He was 

 most active 127-151 A.D., and is best known by his 

 work the Syntaxis, which summarized what was 

 known in astronomy at that time. Ptolemy drew up 

 a catalogue of 1080 stars based on the earlier work 

 of Hipparchus. He followed that astronomer in 

 teaching that the earth is the center of the move- 

 ment of the heavenly bodies, and this geocentric 

 system of the heavens became known as the Ptole- 

 maic system of astronomy. To Hipparchus and 

 Ptolemy we owe also the beginnings of the science 



