Ini/roduGtory Addi^ess. 5 



the character of their mhabitants. This voyage may be consid- 

 ered as originating the science of Political Geography, or the 

 geography of man. 



About the year 200 B, C, Eratosthenes of Gyrene, the keeper 

 of the Royal Library at Alexandria, became convinced, from ex- 

 periments, that the idea of the rotundity of the earth, which had 

 been advanced by some of his predecessors, was correct, and 

 attempted to determine upon correct principles its magnitude. 

 The town of Cyrene, on the river Nile, was situated exactly 

 under the tropic, for he knew that on the day of the summer 

 solstice, the sun's rays illuminated at noon the bottom of a 

 deep well in that city. At Alexandria, however, on the day 

 of the summer solstice, Eratosthenes observed that the vertical 

 finger of a sun-dial cast a shadow at noon, showing that the sun 

 was not there exactly overhead. From the length of the shadow 

 he ascertained the sun's distance from the zenith to be 7° 12', or 

 one-fiftieth part of the circumference of the heavens ; from which 

 he calculated that if the world was round the distance between 

 Alexandria and Gyrene should be one-fiftieth part of the circum- 

 ference of the world. The distance between these cities was 

 5000 stadia, from which he calculated that the circumference of 

 the world was fifty times this amount, or 250,000 stadia. Un- 

 fortunately we are ignorant of the exact length of a stadium, 

 so we have no means of testing the accuracy of his deduction. 

 He was the founder of Mathematical Geography; it became pos- 

 sible through the labors of Eratosthenes to determine the loca- 

 tion of places on the surface of the earth by means of lines cor- 

 responding to our lines of latitude and longitude. 



Claudius Ptolemy, in the second century of the Christian era, 

 made a catalogue of the positions of plans as determined by 

 Erastosthenes and his successors, and with this as his basis, he 

 made a series of twenty-six maps, thus exhibiting, at a glance, 

 in geographical form, the results of the labors of all who pre- 

 ceded him. To him we owe the art of map-making, the origina- 

 tion of Geographic Art. 



We thus see that when Rome began to rule the world, the 

 Greeks had made great progress in geography. They already 

 possessed Comparative, Political and Mathematical Geography, 

 and Geographic Art, or the art of making maps. 



Then came a pause in the progress of geography. 



The Romans were so constantly occupied with the practical 

 affairs of life, that they paid little attention to any other kind of 



