238 THE POPULAR SCIENCE MONTHLY. 



He is even said to have been the inventor of this instrument — which 

 was a simple column, the length of whose shadow determined the posi- 

 tion of the sun — though more probably Thales had brought the knowl- 

 edge of it from Egypt. To Anaximander is also assigned the honor 

 of having made the first geographical chart known among the Greeks. 

 He is even claimed to have made an artificial globe representing the 

 earth, with divisions of land and water. He was not, however, the 

 inventor of maps, since among the Egyptians Sesostris, long before his 

 day, is said to have caused maps to be made. Passing over Anax- 

 imenes and Anaxagoras, the next name worthy of mention is that of 

 Pythagoras (b. c. 570), who, like Thales, had traveled in Egypt, where 

 he is said to have learned the obliquity of the ecliptic. But the great 

 thing for which Pythagoras is remembered by scientists was his doc- 

 trine that the earth revolved about the sun — a truth, however, which 

 he taught only esoterically, his open doctrine being the common one 

 that the sun revolved about the earth. Herodotus (b. c. 484), notwith- 

 standing his extensive travels, contributed nothing to mathematical 

 geography, and had very incorrect ideas as to the several divisions of 

 the world. " Europe," he said, " was as long as Asia and Africa to- 

 gether. The river Nile, before entering Egypt, flowed eastward from 

 near the west coast of Africa." This opinion he formed partly from 

 the account which he said had been given by certain youths who were 

 taken prisoners and carried into the interior of Africa, to a city on the 

 bank of a great river flowing eastward, in which were crocodiles. An- 

 other reason he had was that to the north of the Mediterranean Sea a 

 great river, the Ister (Danube) was known to flow from the extreme 

 west to the east of Europe ; and so, ^'inferring the unknoion from the 

 hnoiim^'' he concluded that the Nile must flow through Africa in a 

 similar way. 



Of more value to science were the observations of Pytheas (about 

 320 B. c), a Greek seaman of Massilia (Marseilles), who sailed far north- 

 ward from the coasts of Britain, where he said the longest day was 

 nineteen hours long, to what he called Thule (probably Iceland), where 

 he said " the summer tropic served for the arctic circle." Notwith- 

 standing certain wild statements of Pytheas, such as that at this place 

 there was found neither earth, air, nor sea, but a mingling of them all ; 

 and that the days and nights there were six months in length, we can 

 not help believing that he did reach the arctic circle, and observe the 

 phenomenon of the sun remaining above the horizon throughout the 

 twenty-four hours. To Pytheas also is due the first suggestion of a 

 computation of latitude. He recorded that the length of the gnomon 

 at Marseilles, the day of the summer solstice, was to the length of the 

 shadow as 120 to 41*8, which, reckoning the tropic at 23° 51' 15", 

 where it was placed by Eratosthenes, would give a latitude of 43° 3' 

 35". If allowance be made for the penumbra, this reckoning will be 

 found very nearly correct. Other names to be noticed are Eude- 



