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years later, corrected and enlarged this map, and added a commentary. (See logog'raphi.) This commentary, of which only fragments are preserved in quotations, is the oldest piece of purely geographical •writing in Greek. The geographical chapters in the history of Her6d6tus (about 450 B.C.) compensate us to a certain extent for the loss of this work, and of the other works of the Logographi on history and geography. But they only treat the eastern half of the known world. It became indeed, in the absence of a regular tradition of geographical science, a usual thing for historians to insert geographical disquisitions into their works. The writings of Thucydldes, XSnophon, Ctesias, EphSrus, TheOpompus, Timseus, and others down to Polybius, afford examples of this.
The first purely geographical work which has come down to us in a complete state is the Periplus bearing the name of Scylax, written in the first part of the 4th century b.c. This is a description of the coast of the Mediterranean. About the same time the astronomer Eudoxus of Cnldus made a great advance in the theory of physical geography. He was the first who adduced mathematical proof of the spherical shape of the earth, which had been asserted before his time by PythagSras. The division of the globe into five zones (two frigid, two temperate, and one torrid) is also due to him. About 330 B.C. Pytheasof Massilla explored towards the N.W. as far as the northern end of the British Islands and the coasts of the German Ocean. About the same time the campaigns of Alexander the Great opened up Asia as far as India to Greek research. Ngarchus made a report of exceptional value on his coast voyage from the Indus to the Euphrates. All these discoveries were embodied, about 320 b.c. in a new map by Dicsearchus of Messana, a disciple of Aristotle. He was the first savant who treated physical geography in a scientific manner. He assumed the existence of a southern hemisphere, and made an estimate of the earth's circumference, to which he gave the exaggerated measurement of 40,000 miles. His map remained for a long time the standard work of the kind. The southern and eastern parts of India were still further opened out under Alexander's successors, in consequence of the campaigns of the Seleucldse, and several journeys undertaken by ambassadors, among which that of Megasthenes should be mentioned. The commercial expeditions of the Ptolemies i
brought in fresh knowledge of the coasts of Arabia and E. Africa.
The first man who arranged the mass of geographical materials hitherto collected, into a really scientific system, was Eratosthenes of Cyrene (about 276-175 b.c.). Hia materials he found in the rich collections of the Alexandrian library, Alexandria being then the central point of the commerce of the world. He was fully equipped for his task by his acquirements both in physical science and mathematics, and in history and philology. He endeavoured for the first time to estimate the earth's circumference by a measurement of degrees carried out over a space of 15 degrees of latitude. The imperfection of his method brought out too large a quantity, 25,000 geographical miles. The name of Hipparchus of Nlcsea (about 140 b.c.) marks a considerable advance. He may be called the founder of mathematical geography, as he applied geographical length and breadth to determine the position of places on the earth's surface. He also superseded the rectangular and equidistant projection of parallels and meridians, hitherto used in maps, by a projection which, with few modifications, is identical with the one now in use. The parallels were represented by segments of a circle, the meridians by straight lines or curves, corresponding with the portion of surface to be represented, drawn at distances corresponding to the actual distances on the surface of the globe. The estimate of the earth's circumference which was accepted as correct down to the 10th century a.d., was that of Posidonlus of Apamea (about 90 b.c.). Taking as his basis the measurement of the shortest distance from Alexandria to Rhodes, he brought out the result as 18,000 geographical miles, instead of 21,600 (or about 25,000 English miles.)
Only fragments remain of the writings of these geographers, and others contemporary with them. But we possess the great work of Strabo of Amaseia, finished about 20 a.d., the most important monument of descriptive geography and ethnology which has come down from Greek antiquity. Thanks to the Roman conquest, he was in a position to give a more accurate description of the West than his predecessors. Up to this time all that the Romans had done for geographical research was to open up Western Europe and Northern Africa to the Greek savants. An immense service was rendered to science by Agrippa, under the direction of Augustus.