Geography. regard to the knowledge of the form and extent of the earth. Thales, and his pupil Anaximander, reputed to have been the first to draw maps, exploded many errors, and paved the way, by their observations, for the attainment of a sounder knowledge. The logographiers contributed at this period to the same end by the descriptions which they gave of various parts of the carth; of these, perhaps the most interesting to us is the narrative of the Carthaginian Himilco, who discovered the British islands, including the Estrymnides, which he described as being a four months' voyage from Tartessus. With Herodotus of Halicarnassus (born 485 B. C.), who may be regarded as the father of geography as well as of history, a new era began in regard to geographical knowl edge, for although his chief object was to record the struggles of the Greeks and Persians, he has so minutely described the countries which he visited in his extensive travels (which covered an area of more thrn 31° or 1700 m. from e. to w., and 24 or 1660 m. from n. to s.), that his history gives us a complete representation of all that was known of the earth's surface in his age. This knowledge, which was extremely scanty, consisted in believing that the world was bounded to the s. by the Red sea or Indian ocean, and to the w. by the Atlantic, while its eastern boundaries, although admitted to be undefined, were conjectured to be nearly identical with the limits of the Persian empire, and its northern termination somewhere in the region of the amberlands of the Baltic, which had been visited by Phoenician mariners, and with which the people of Massilia (the modern Marseilles) kept up constant intercourse by way of Gau! and Germany. In the next century, the achievements of Alexander the Great tended materially to enlarge the bounds of human knowledge, for while he carried his arms to the banks of the Indus and Oxus, and extended his conquests to northern and eastern Asia, he at the same time promoted science, by sending expeditions to explore and survey the various provinces which he subdued, and to make collections of all that was curious in regard to the organic and inorganic products of the newly visited districts; and hence the victories of the Macedonian conqueror formed a new era in physical inquiry generally, as well as in geographical discovery specially. While Alexander was opening the east to the knowledge of western nations, Pytheas, an adventurous navigator of Massilia, conducted an expedition past Spain and Gaul through the channel, round the e. of England into the Northern ocean, where, after six days' sailing, he reached Thule (conjectured to be Iceland). and returning, passed into the Baltic, where he heard of the Teutones and Goths. Discovery was thus being extended both in the n. and e. into regions whose very existence had never been suspected, or which had hitherto been regarded as mere chaotic wastes. An important advance in geography was made by Eratosthenes (born 276 B.C.), who first used parallels of longitude and latitude, and constructed maps on mathematical principles. Although his work on geography is lost, we learn from Strabo that he considered the world to be a sphere revolving with its surrounding atmosphere on one and the same axis, and having one center. He believed that only about one-eighth of the earth's surface was inhabited, while the extreme points of his habitable world were Thule in the n., China in the e., the Cinnamon coast of Africa in the s., and the Prom. Sacrum (cape St. Vincent) in the west. During the interval between the ages of Eratosthenes and Strabo (born 66 B.C.), many voluminous words on geography were compiled, which have been either wholly lost to us, or only very partially preserved in the records of later writers. Strabo's great work on geography, which is said to have been composed when he was 80 years of age, has been considered as a model of what such works should be in regard to the methods of treating the subject; but while his descriptions of all the places he has himself visited are interesting and instructive, he seems unduly to have discarded the authority of preceding writers. The wars and conquests of the Romans had a most important bearing upon geogra phy, since the practical genius of the Roman people led them to the study of the material resources of every province and state brought under their sway, and the greatest service was done to geographical knowledge by the survey of the empire, which was begun by Julius Cæsar, and completed by Augustus. This work comprised a description and measurement of every province by the most celebrated geometricians of the day. Pliny (born 23 A.D.), who had traveled in Spain, Gaul, Germany, and Africa, has left us a compendium of the geographical and physical science of his age in the four books of his Historia Naturalis which he devotes to the subject. He collected with indefatigable industry the information contained in the works of Sallust, Cæsar, Tacitus, and others, to which he added the results of his own observations, without, however, discriminating between fact and fiction. The progress that had been made since Cæsar's time in geographical knowledge is evinced by Pliny's notice of arctic regions and of the Scandinavian lands, and the accounts which he gives of Mt. Atlas, the course of the Niger, and of various settlements in different parts of Africa, while his knowledge of Asia is more correct than that of his predecessors, for he correctly affirms that Ceylon is an island, and not the commencement of a new continent, as has been generally supposed. The study of geography in ancient times may be said to have terminated with C. Ptolemy, who flourished in the middle of the 2d c. of our new era. His work on geography, in eight books, which continued to be regarded as the most perfect system of the science through the dark middle ages down to the 16th Geography. c, gives a tolerably correct account of the well known countries of the world, and of the Mediterranean, Euxine, and Caspian, together with the rivers which fall into thoso seas, but it added little to the knowledge of the n. of Europe, or the extreme boundaries of Asia or Africa. Yet, from his time till the 14th c., when the records of the travels of the Venetian Marco Polo opened new fields of inquiry, the statements of Ptolemy were never questioned, and even during the 15th c., it was only among a few German scholars at Nürnberg that the strange accounts given of distant eastern lands by the Venetian traveler were received as trustworthy where he differed from Ptolemy. Marco Polo had, however, unfortunately made no astronomical observations, nor had he even recorded the length of the day at any place, and hence the Nürnberg geograph ers, who had no certain data for estimating the extent of the countries which he had traversed, were the means of propagating errors which led to results that were destined to influence the history of mankind; for, taking Ptolemy's tables as their basis, they had incorporated on their globes and maps the results of their own rough estimates of the length of Marco Polo's days' journeys, and they had thus represented the continent of Asia as extending across the Pacific, and having its eastern shorcs somewhere in the region of the Antilles. These erroneous calculations misled Christopher Columbus to the false assumption that, by sailing 120° w., he would reach the wealthy trading marts of China, and the result of this conviction was his entering upon that memorable expedition which terminated in the discovery (in 1492) of the continent of America. Although there can be no doubt that the American continent was visited in the 9th and 10th c. by Northmen, the event remained without influence on the history of discovery, and cannot therefore detract from the claims of Columbus. This momentous discovery, which had been preceded in 1486 by the exploration of the African coast as far as the cape of Good Hope (which was doubled by Vasco da Gama in 1497), was followed by a rapid succession of discoveries; and within 30 years of the date of the first voyage of Columbus, the whole coast of America from Greenland to cape Horn had been explored, the Pacific ocean had been navigated, and the world circumnavigated by Magellan (q.v.) the coasts of eastern Africa, Arabia, Persia, and India had been visited by the Portuguese, and numerous islands in the Indian ocean discovered. The 16th c. was marked by continued attempts, successful and unsuccessful, to extend the sphere of oceanic discovery; and the desire to reach India by a shorter route than those by the cape of Good Hope or cape Horn, led to many attempts to discover a n.w. passage, which, though they signally failed in their object, had the effect of very materi ally enlarging our knowledge of the arctic regions. The expeditions of Willoughby and Frobisher in 1553 and 1576, of Davis (1585), Hudson (1607), and Baffin (1616), were the most important in their results towards this end. The 17th and 18th centuries gave a new turn to the study of geography, by bringing other sciences to bear upon it, which, in their turn, derived elucidation from the extension of geographical knowledge; and it is to the aid derived from history, astronomy, and the physical and natural sciences, that we owe the completeness which has characterized modern works on geography. In the 17th c., the Dutch, under Tasman and Van Diemen, made the Australasian islands known to the civilized world; and in the latter half of the 18th c., capt. Cook extended the great oceanic explorations by the discovery of New Zealand and many of the Polynesian groups; but he failed to find the antarctic continent, which was first visited in 1840 by American, English, and French expeditions, under their respective commanders, Wilkes, Ross, and Dumont d'Urville. Polar exploration, after having been for a time in abeyance, has within late years been vigorously prosecuted by the United States and various European countries. In America, the travels of Humboldt, Lewis and Clark, Fremont, and others, have done much to make us acquainted with broad general features, but much remains to be done in regard to special districts of Central and Southern America. In Asia, numerous travelers, geographers, and naturalists have contributed to render our knowledge precise and certain in respect to a great part of the continent, whose natural characteristics have been more especially represented by the great physicist Ritter; while we owe a large debt of gratitude to the Jesuit missionaries, whose indefatigable zeal has furnished us with a rich mass of information in regard to minor details of Asiatic life and nature. In Africa, the combined influences of a deleterious climate, and a religion hostile to European advance, have hitherto retarded explorations into the interior; but notwithstanding these obstacles, much light has been thrown on the character and condition of the African continent by many of its greatest explorers-as Bruce, Park, Clapperton, Adamson, the Landers, Burton, Speke, Barth, Vogel, Livingstone, Cameron, and Stanley. In Australia, although much still remains to be done, the obscurity which had hitherto hung over the interior has been to a great extent diminished by the explora tions of Sturt, Eyre, Leichhardt, and the brothers Gregory; and still more by the highly important labors of Burke and Wills, who in 1860 crossed the Australian continent from Melbourne to Carpentaria. Although both these intrepid explorers perished miserably from starvation on their return route, their journals and the description that has been given by them and their sole-surviving companion, King, of the country through which they passed are of value; nevertheless, they overestimate the fertility of that portion of the continent of Australia, as later explorations proved. The progress which has marked recent discovery has been materially aided by the Geology. encouragement and systematic organization which have been given to plans of explora tion by the public governments of different countries, and by the efforts of the numerous geographical societies which have been formed during the present century both at home and abroad; while the constantly increasing mass of information collected by scientific explorers is rapidly diffusing correct information in regard to distant regions, and thus effectually dispelling the numerous fallacies which have hitherto obscured the science of geography. Among the numerous works of authority on the subject of geographical discovery, the following may be consulted with advantage: Hudson's Geographi Graci minores; Précis de Geographie Universelle, by Malte Brun; Manual of Geographical Science (mathematical, physical, historical, and descriptive), 1860; Latham's Germania of Tacitus; Humboldt's Hist. crit. de l'Hist. de la Géographie, Asie, Centrale, and the Cosmos; Ritter's Asien; Kloeden's Erdkunde. The recent progress of geographical discovery may be traced in Petermann's Mittheilungen, the Geographical Magazine, and the Proceedings of the Geographical Society. See also works by Bunbury and Kiepert (1880, 1881). GEOGRAPHY, MEDICAL. The liability of particular localities to become the centers of special diseases, or groups of diseases, has been observed from the most ancient periods, as we have excellent evidence in the hippocratic treatise. On airs, waters, and places, one of the undoubtedly genuine works of the great Greek physician, and one of those which best sustains his traditional reputation. Now-a-days, medical geography has become a most elaborate and carefully investigated branch of medical science, the details of which, though of considerable popular interest, are far too complicated and too technical to be discussed with advantage here. The reader may be referred to the articles ENDEMIC DISEASE, CLIMATE, AGUE, DYSENTERY, GOITER, LEPROSY, YELLOW FEVER, PLAGUE, REMITTENT FEVER, for incidental illustrations of the subject. Generally speaking, the tropics are subject to diarrheal diseases, with acute affections of the liver, and severe remittent or pestilential fevers, caused by the exalted temperature acting on the soil, and producing emanations very destructive of health; the like causes in more temperate climates causing ague and diarrhoea, especially during the summer and autumn in low-lying, ill-drained localities. Temperate climates are also subject in a peculiar degree to pulmonary diseases, and to all manner of contagious fevers, the result of overcrowding and confined air. Certain diseases, again, as goiter, leprosy, and some animal parasites (see ENTOZOA), appear to have no relation to climate, but are found to affect, more or less exclusively, certain well-defined districts of country; as in the case of the Guinea-worm, the Egyptian ophthalmia, the pellagra of Lombardy, the beri-beri of Ceylon and the Malabar coast, and the elephantiasis of the Indian peninsula generally. The best works on medical geography are those of Mühry, in Germany, and Boudet, in France, which are remarkably learned and complete treatises on the whole subject. A more recent one still is that of Dr. August Hirsch of Danzig, a work of immense labour and erudition, not yet completed. On tropical diseases generally, the English works of Annesley, Twining, Morehead, and sir Ranald Martin are of confirmed reputation. GEOLOGY (Gr. ge and logos), the science of the earth, should include all the sciences that treat of the constitution and distribution of the inorganic matter of the earth, as well as those which describe the living beings that inhabit it; just as astronomy includes the whole science of the heavenly bodies. In this wide sense, as comprising all the physical sciences, it has sometimes been used. As usually employed, however, it has a much more limited meaning, being confined to that section of the sciences which takes cognizance of the hard crust of the earth-of the materials of which it is composed, and of the manner in which these materials are arranged. The structure of the earth received little attention from the ancients: the extent of its surface known was limited, and the changes upon it were neither so speedy not violent as to excite special attention. The only opinions deserving to be noticed, that have come down to us, are those of Pythagoras and Strabo. They both observed the phenomena which were then altering the surface of the earth, and proposed theories for explaining the changes that had taken place in geological time. The first held that, in addition to volcanic action, the change in the level of sea and land was owing to the retiring of the sea; while the other maintained that the land changed its level, and not the sea, and that such changes happened more easily to the land below the sea because of its humidity. From the fall of the Roman empire, during the dark ages, the cultivation of the physical sciences was neglected. In the 10th c., Avicenna, Omar, and other Arabian writers, commented on the works of the Romans, but added little of their own. Geological phenomena attracted attention in Italy in the 16th c., the absorbing question then being as to the nature of fossils. On the one side, it was held that they were the results of the fermentation of fatty matter, or of terrestrial exhalations, or of the influence of the heavenly bodies, or that they were mere earthy concretions or sports of nature; while only a few maintained that they were the remains of animals. Two centuries elapsed before this opinion was generally adopted. At the outset, it was unfortunately linked to the belief that the fossils were relics of the Noachian deluge. Steno (1669) observed a succession in the strata, and asserted that there were rocks older than the fossiliferous strata in which no organic remains occur; he also distin |