THE ALEXANDRIAN PERIOD 71 



a circular arrangement of mirrors. This feat was 

 related for the first time by Lucius of Samosatus in 

 the second century, so it is open to question, although 

 Buffon has demonstrated its physical possibility. It 

 is well known how at the fall of Syracuse, Archimedes 

 was brutally slain by a soldier, contrary to the express 

 desire of Marcellus, and how his tomb was discovered 

 by Cicero many years after (Tusculanes, Bk. V, ch. 23). 

 According to his own testimony (Heiberg edition, 

 II, p. 248, 8) Archimedes was initiated to astronomy 

 by his father Pheidias ; he afterwards had Conon as 

 his friend and fellow-student, and showed himself 

 unrivalled in the construction of astronomical instru- 

 ments. He constructed two planetaria, which were 

 taken to Rome after the fall of Syracuse. One was 

 placed in the temple of Victory, the other was pre- 

 served by the family of Marcellus, and was admired 

 by Cicero, who speaks of it in the following terms : 

 " What is most to be admired in the invention of 

 Archimedes is that he was able with a single motor 

 to reproduce all the unequal and different movements 

 of the heavenly bodies" (Repub., I, ch. 14). In 

 another field, the pursuit of astronomy certainly 

 led Archimedes to the study of catoptrics (laws of 

 reflection), and to the creation of an ingenious system 

 of numeration by which numbers of any desired 

 magnitude can be expressed. After having benefited 

 by his father's teaching, Archimedes, as Diodorus of 

 Sicily relates, must have sojourned for some time in 

 Egypt, or he would not have brought out his works 

 in Alexandria, dedicating them to Eratosthenes, 

 Conon and Dositheus, who lived in that city. During 

 that sojourn he must have had some painful experi- 

 ences with certain pedantic professors, for speaking 

 of some problems propounded by Conon, the solution 

 of which was impossible, he says this : " Those who 

 pretend to have discovered them all, without pro- 



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