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 the Persian Empire hitherto only known to them by report, his campaigns extended their knowledge over the regions watered by the Indus and its five great tributaries (the Panjab and Scinde), and, even farther than his arms actually penetrated, to the banks of the Ganges. The lower course of the Indus, and the shores between its mouth and the head of the Persian Gulf, were explored by Nearchus; and some further knowledge was gained of the nomad tribes which roamed (as they still do) over the vast steppes of Central Asia by the attempt of Alexander to penetrate on the NE. beyond the Jaxartes (Sihon); while, on all points, the Greeks were placed in advanced positions from which to acquire further information, especially at Alexandreia, whither voyagers constantly brought accounts of the shores of Arabia and India, as far as the island of Taprobane, and even beyond this, to the Malay peninsula and the coasts of Cochin-China. The knowledge acquired in the campaigns of Alexander was embodied in a map by Dicaearchus, a disciple of Aristotle.

On the E. and N. the wars and commerce of the Greek kingdom of Syria carried Greek knowledge of Asia no further, except to a small extent in the direction of India, where Selencus Nicator (B.C. 314) led an expedition as far as the Ganges, and sent ambassadors to, where their prolonged residence enabled them to learn much of the peninsula of India. The voyage of Patrocles round the shores of the Indian Ocean also deserves mention. (Dict. of Biog. art. Patrocles.) Of course more acquaintance was gained with the countries already subdued, until the conquests of the Parthians shut out the Greeks from the country E. of the Tigris-valley; a limit which the Romans, in their turn, were never able to pass.

Meanwhile, in the other great seat of his Eastern Empire, Alexander's genius was bearing fruits which we are still reaping. Whatever judgment may be formed of the conqueror of Greece and Persia, the founder of Alexandreia demands an exalted place among those who have benefited mankind by the extension of their knowledge. There, in a position accessible by sea from all the coasts of the east and of the west, commerce was maintained and extended by the advance of science, whose aid she rewarded by contributions of fresh knowledge from remote countries; and, under the protection of the first Ptolemies, mathematical and physical theories, and the observations of travellers and merchants, advanced hand in hand, and laid the first foundation of a real system of geographical science. Whatever aid the records of past inquiries could furnish was provided for by the foundation of the celebrated library, which we may safely assume to have contained accounts of Phoenician voyages, which the conquest of Tyre transferred to the Macedonians. Aristotle had already established the globular figure of the earth, and now Eratosthenes (about B.C. 270 — 240) made the great stride forwards in mathematical geography, of drawing lines upon its surface, to which to refer the poSitions of places, namely, from E. to W. the Aequator and Tropic of Cancer, and seven other parallels of latitude through important places; and from N. to S., two boundary lines, marking the limits of the known world» and, between these, seven meridians through important places. (See Dict. of Biog. art. Eratosthenes.) Instruments having been invented for taking latitudes, and those latitudes being compared with the standard parallels,the positions of places were now laid down with an accuracy previously unattainable. Still, however, the geographer was dependent, for the determination of longitudes, on computations by days' journeys, and so forth. During the same period the means of information were increased, not only by the increase of commerce in the Indian Ocean, but by the establishment of the Greek kingdom of Bactria in Central Asia. Accordingly we find that the knowledge of Eratosthenes and his followers embraces the great mountain-chains N. of India, the, , and , and extends E. as far as the. The mathematical geography of Eratosthenes was greatly improved by Hipparchus, B.C. 150. (See art in Dict. of Biog.)

The extension of the Roman empire over Asia Minor and Syria, and their wars with Mithridates and the Parthians, not only added greatly to the accuracy of their information respecting Western Asia, but extended it, on the N., into the heart of the Caucasian countries, a region of which the Greeks had scarcely any knowledge; while, at the opposite extremity, the expedition of Aelius Gallus made them far better acquainted with the peninsula of Arabia. [.] The fruits of these discoveries were stored up by the administrative ability of Julius Caesar, Augustus, and Agrippa, who caused measurements and observations to be taken, and recorded in maps and itineraries; and by the literary labours of the great geographer Strabo, whose immortal work is founded on an extensive knowledge and diligent criticism of the writings of the Greek geographers, on the further discoveries made up to his time, and on his own personal observations in extensive travel. (See the art. in the Dict. of Biog.) The brief epitome of Pomponius Mela, who wrote under Claudius, and the elaborate compilation of the elder Pliny, complete the exhibition of Greek and Roman knowledge of Asia (as of the other continents), under the first Caesars.

Meanwhile, though the Tigris and Euphrates had become the final limit of the Roman empire to the E., further advances were made in Armenia and the Caucasus; the Caspian Sea, and the nomad tribes of the North became better known; and information was obtained of a great caravan route between India and the shores of the Caspian, through Bactria, and of another commercial track, leading over the high table-land of Central Asia to the distant regions of the. The wealth and luxury of Rome and her chief provinces were making continually new demands on the energies of commerce, which led to constant accessions of knowledge, especially in the extreme regions of SE. Asia. Meanwhile, a fresh step in the scientific part of geography was made by Marinus of Tyre, under Antoninus Pius, A.D. 150. (See art. in Dict. of Biog.)

Under M. Aurelius, the geography of the ancients reached its highest point, in the celebrated work of Ptolemy, A.D. 160, which remained the text-book of the science down to the Middle Ages. (See art. in Dict. of Biog.) He improved the system of Marinus; constructed a map of the world on a new projection; and tabulated the results of all the geographical knowledge of his time in a list of countries, and the chief places in them, with the longitude and latitude of each appended to its name. His diligence and judgment have received continual confirmation from new discoveries; the greatest defect of his work being that which resulted necessarily from the want of a method for fixing the longitude