THE BEGINNINGS OF GEOGRAPHICAL SCIENCE. 239 



mus, the first Greek to give the angle of the ecliptic — as subtended 

 by the side of a pentadecagon, or equal to 24° — and Eudoxus, who 

 wrote a work on the " Period or Circumference of the Earth." 



This brings us down to the school of Alexandria. Alexander had 

 founded near the Canopic mouth of the Nile a city which was destined 

 long to perpetuate his name and glory. The glory was to come not so 

 much from its commercial importance, though it rose to be the chief 

 commercial city of the world, as from its intellectual supremacy. It 

 Avas the ambition of the Ptolemies to make their capital the intellec- 

 tual center of the world, and in this they were successful. The Attic 

 and Ionian scholars gave place to the Alexandrian, not only in the 

 department of letters, but also in the domain of science. One of the 

 librarians of the great Alexandrian Library was Eratosthenes (b. c. 

 270), who may justly be called the Father of Geography. His work is 

 in great part preserved to us in the pages of Strabo and Pliny. Hav- 

 ing under his eye everything that had ever been written upon the 

 subject, he first combined the whole into a complete system, which can 

 to-day be restored. The map of the world which he prepared, if less 

 perfect in some respects than Ptolemy's, was in other respects far 

 more perfect ; indeed, was the most correct which the world was to 

 see down to the sixteenth century a. d. Besides other and doubtless 

 very important data, of which we have no information, Eratosthenes 

 must have had a record of an expedition undertaken in the fifth cen- 

 tury B. c. by Hanno, under the direction of the Carthaginian Senate, 

 in which he sailed down the west coast of Africa as far as to the Gulf 

 of Benin ; as well as an account of the observations made by the fol- 

 lowers of Alexander during his march through Asia, and by his naval 

 commander Nearchus, who conducted the fleet from the mouths of the 

 Indus along the coast to the Euphrates. 



After him came Hipparchus, who lived at Rhodes (b. c. 160-145). 

 His great merit was in his use of astronomical observations to deter- 

 mine positions upon the earth, instead of depending upon itinerary dis- 

 tances from a few known points, as had been the method of Eratos- 

 thenes. But the age did not appreciate his work, and the science was 

 not to realize the advance which was thus made possible; nearly three 

 centuries must elapse before the fruit of his labors was to appear. Era- 

 tosthenes had been able to determine latitude by the heavenly bodies, 

 but not longitude. Hipparchus showed how this also could be done, 

 by observing the eclipses of the sun and moon. Again, he invented 

 the method of projection in map-making, another most valuable con- 

 tribution to the science which was to be despised until a coming 

 age. 



Posidonius is a name to be remembered for an error which he in- 

 troduced into the science, so successfully that it remained for many 

 centuries. What it was we shall see under Ptolemy. 



Strabo (54 b. c), notwithstanding his voluminous work on geogra- 



