materially increased by the explorations of Pike from St. Louis to Chihuahua, via the Kansas, Arkansas, and the Rio Grande.

Kotzebue and Zagostin in the first half, and Dall, Kennicott, and Allen in the last half, of the century have outlined the general features of Alaska. In the Stikine, Klondike, Tanana, Nome, and Koyukuk regions the gold hunters have explored thoroughly. In Canada the early discoveries of Franklin, Richardson, Rae, and Back have been supplemented by Petitot in the Mackenzie Basin, Dawson and Ogilvie in the Yukon watershed, Bell and Tyrrell around Hudson Bay, Boas in Baffin Land, and Low in Labrador.

As regards the United States, the country west of the Mississippi was almost entirely unknown in 1800. The early trans-Mississippi explorations form one phase of the history of the United States Army. The most fruitful in results of such journeys is that of Lewis and Clarke (1804-'06). They ascended the Missouri from mouth to source, crossed the continental divide, traced thence the Snake and Columbia to the ocean, and returned via the Yellowstone. For the first time the United States was crossed from the Atlantic to the Pacific. This demonstration of the practicability of overland travel was an essential factor in the occupancy of Oregon, which gave the first foothold for the American on the Pacific Coast.

MAPPING THE GREAT WEST

Pike explored the valleys of the upper Mississippi, Arkansas, and Rio Grande, crossed part of Chihuahua and Texas, then unknown countries. Bonneville (1832-36) explored the valleys of the Platte, Green, and Yellowstone, and, pioneer of the Oregon trail, twice crossed to the Columbia, passing west via the Snake River, the Grand Ronde, and Blue Mountains. He also made known

the great basins of Salt Lake and Humboldt River and the pass across the Nevadas to the Sacramento. Bonneville first correctly charted the hydrography of the trans-Rocky Mountain regions, and eliminated the Rio Buenaventura and other mythical streams. Frémont's journeys were important as initiating an extensive series of scientific explorations. Kearney surveyed the boundaries of Texas and Louisiana, Boone the country between the Arkansas and Canadian, and Emory from Leavenworth to San Diego via the Arkansas, Del Norte, and Gila.

Among the many expeditions may be mentioned that of Simpson to the Navajo country, Stansbury to Salt Lake, Sitgreaves to the Zuñi and Colorado Rivers, and Mullen from Walla Walla to Fort Benton. Important surveys are those of the Pacific Railway route by McClellan, Whipple, Parke, Williamson, and Derby; the Mexican boundary by Emory, the northwestern boundary (1857-'61), and in later years those of King. Hayden, Powell, and Wheeler, which have elucidated most of the geographical problems in the United States.

RIVALRY IN ASIA BEGAN EARLY

In the geographical as in the political evolution of Asia the potent forces have been Great Britain and Russia, so that Northern and Southern Asia have been almost separate fields of enterprise for the dominant nation, with Central Asia as debatable ground for rivalry by both nations. In Northern Asia explorations in the early century were confined largely to the local extensions of knowledge, except additions to the New Siberian Islands by Samkif, Sirovatskof, Hedenstrom, and Sannikof, 1805-'11; of the Siberian Ocean by Wrangell and Anjou, 1820-'23, and in Nova Zembla by Lütke, 1821-'24; PachtusSow, 1832-35, and Baer and Zivolka 1837-38.

The foundation of the Imperial Russian Geographical Society in 1845 gave impetus and direction to Asiatic discoveries, increased knowledge of the Russian Empire being the aim. From 1849 to 1857 Hoffman, Aksakof, and others explored the Ural region and the ethnographic features of Russia proper and of Western Siberia. Extending in scope from 1857 to 1871, besides Siberian researches in Amur, Usuri, and Saghalin, the Caucasian and Aral-Caspian regions were explored in the southwest, while to the east many expeditions entered Turkestan, Manchuria, Khorassan, and Mongolia.

Between 1871 and 1885 Central Asia, Mongolia, and Western China were explored, largely through Prjevalsky, and international polar stations were established on the Lena and in Nova Zembla. Severtsoff and Fedchenko explored Turkestan minutely; the deserts of northwestern Siberia and Lake Baikal were examined and a sea route opened from Tobolsk by way of the Kara Sea to St. Petersburg.

TIBET IS A MYSTERY YET

In

During the last fifteen years attention has been paid to Caucasia, Turkestan, the Amur, and Black Sea regions. these years perhaps the most interesting explorations are those of Hedin, who crossed the desert of moving sand hills between the Yarkand and Khotan Rivers, outlined the northern rim of the great Tibetan Plateau, and examined Lob Nor Basin.

Explorations in Southern Asia originated in the desire to extend inland the sphere of British influence. Political considerations speedily entered into the problem, and those barriers proved more difficult to surmount than physical obstacles. In reaching the Himalayan foothills, and later in passing across the ranges into Afghanistan and Tibet, the explorer necessarily awaited brief inter

vals in the wars of conquest and occupation.

Manning succeeded in entering Tibet in 1811, but was soon expelled. Nonintercourse was so rigidly enforced that the British surveys had recourse to selected native agents, and most of the early advances were made through secret journeys of pundits, among whom Chandra Das stands foremost. As usual, much has been learned by missionary labors, especially in Tibet, through Huc and Desgodins, the latter also contributing much to a knowledge of Indo-China. In recent years both countries have been explored by Rockhill, Bonvalot, Littledale, Szechenyi, Henri of Orléans, and others, especially the pundit Nain Singh, under conditions that leave much to be added.

Japan has opened her unknown empire to the world. While much has been done by Japanese travelers to make its geography known, yet the geological researches of Naumann should be noted.

MAP OF AFRICA FILLED IN

The extent to which exploration changed the map of Africa during the nineteenth century is known only to professional geographers. It is true that in 1800 the entire coast of Africa was known with some definiteness through the exertions of Portuguese navigators in previous centuries. Yet apart from the valley of the Nile geographic knowledge of the interior was confined to a scant hundred miles southward from the Mediterranean and northward from the Cape of Good Hope and to the estuaries of the Zambezi, Kongo, and Niger.

Geographic knowledge stopped almost within sight of the sea or the Lower Nile. Scarcely fifty years since. there appeared, from 5 degrees north to 10 degress north, on the best maps of Africa, the legend, "Kong Range, mountains supposed to extend across

the continent." Today it is known that this central area forms part of the great Kongo Basin, with a population of more than forty millions.

In outlining the march of exploration toward the interior of the "Dark Continent" only the most succinct account is possible. For clearness of statement, explorations are treated under five general heads: First, trans-Saharan, from the Mediterranean; second, the Niger regions; third, the lake regions near the Upper White Nile; fourth, the Zambezian region, and, fifth, the Kongo Basin.

According to different definitions of a desert, the Sahara varies in area from 2,500,000 to 3,500,000 square miles, of which the eastern third is generally known as the Libyan Desert Hitherto this desert area, with scant water, intense heat, and whirling duststorms, interposed an inaccessible barrier between the Hemitic nations of the Mediterranean coast and the negro tribes of the Sudan.

SAHARA'S BARRIERS OVERCOME

Explorations of the Sahara were fruitJess until Oudney, Denham, and Clapperton crossed (1822-'24) from Tripoli to Lake Chad, in the Sudan. Laing, following, crossed from Tripoli via Ghadames and Tuat to Timbuktu, the mysterious city of strangely exaggerated importance from previous centuries. Panet, Vincent, Duveyrier, and Lenz explored the desert between Senegal and Southeastern Algeria.

It was Barth who gave the first definite account of the Saharan region after a journey of great extent and importance. Starting from Tripoli, he crossed the Sahara to Lake Chad, passed Northern Hausaland to the Niger at Say, and thence reached Timbuktu. Returning northeast through Sokoto to Kukawa, he explored Bornu. Barth's journeys were of great value, for he not only made

known to the world the existence and accessibility of hundreds of thousands of square miles of fertile territory, but he also gave in five volumes an enormous amount of geographical information, in which he treated quite thoroughly the ethnology of the various tribes of the Central Sudan. His successor, Rohlfs, after exploring Southern Morocco, penetrated the Sahara to the oases of Tuat and Ghadames, and those of the districts of Fezzan and Tibesti. He then crossed from the Mediterranean to the Guinea coast via Bornu and Lagos, on the Niger, the first European to make the journey. Later (1873-'78) he explored the oases in the Libyan Desert.

The Sahara, instead of being a low desert of marine origin, is an elevated plateau, which has been enormously denudated by the disintegration of its rocks. through temperature changes and the distribution of its dust by high winds. It is not entirely rainless; has many fertile oases and only needs abundant water to produce luxuriant vegetation.

The first Europeans to cross Africa from east to west north of the equator were Matteucci and Massari, who traveled from Suakin via Kordofan, Wadai, and Kano to the Niger. Nachtigal (1869-'70) made a journey from Tripoli via Fezzan to the Libyan Desert, where he explored the remarkable mountainous region of Tibesti. Examining the Lake Chad district, he reached Egypt via Wadai and Darfur.

NIGER AND NILE AN OPEN BOOK

The mystery of the Niger, long erroneously supposed to flow through the Sudan to the west, was partly solved by Mungo Park, who, starting from Gambia, in his first journey reached Segu, on the Niger. His second expedition. (1805 ended in failure. Clapperton. renewing the survey, perished, but his faithful assistant, Richard Lander, definitely solved (1830) the mystery of the

Niger by descending from Bussa to the mouth of the stream.

French energy has explored Senegal and Gambia by the journeys of Rubault, Mollien, De Beauford, and especially Caillié.

The great mystery of the Nile sources, after twenty centuries of speculation, has been solved by the labors of various explorers, most largely by Baker, Speke, and Stanley. Its largest lake source, Victoria Nyanza, was discovered by Speke, who missed Albert Nyanza. Baker discovered the source of the Blue (Abyssinian) Nile and the Albert Nyanza of the main or White Nile. To Stanley belongs the honor of the discovery of the remotest source, Albert Edward Nyanza, which feeds the Albert Nyanza through the Semliki River.

The fabled Mountains of the Moon have given place in Eastern Africa to a most remarkable lacustrine system. The vast equatorial lakes cover extensive regions, feed some of the largest rivers of the world, and by their transportation facilities favor commerce. Their cen

tral situation between the Cape and Cairo, convenient to the Indian Ocean and on the confines of the Kongo Basin, caused them to be recognized as the central key to African domination by Germany and Great Britain, who now control the region.

The largest lake, Tanganyika, was discovered by Burton, while Livingstone contributed Nyassa, Moero, Bangweolo, and others. Joseph Thompson, exploring south from Tanganyika, discovered Lake Rukwa and also traversed unknown Masailand.

LIVINGSTONE'S GREAT WORK

The discovery of the equatorial lakes was of subordinate import to that of the Kongo Basin, which grew out of missionary labors in South Africa. To the genius and energy of two men, David Livingstone and Henry M. Stanley, are

primarily due the exploration and utilization of the vast unexplored regions between the Sudan and the Orange

River.

Unquestionably the missionary Livingstone, who settled in Bechuanaland in 1841, was one of the greatest of African explorers. First discovering Lake Ngami, he turned his attention to the Zambezi Valley, and practically covered this basin in 1851-'56, and later, in 1858-'64, explored Lake Nyassa and the adjacent country. Most important results flowed directly and indirectly from the last journeys of his life, in 1866-73, when, crossing the watershed to the very sources of the Kongo, he discovered Lakes Moero and Bangweolo, the Luapula and Lualaba Rivers, now recognized branches of the Kongo.

STANLEY

Stanley, who found the long-lost Livingstone, completed the exploration of the main Kongo Basin in a journey. (1875-'78) which in its discoveries and results is unequaled in African exploration. His circumnavigation of the great lakes, Victoria Nyanza and Tanganyika, was important, but the crossing to the watershed of the Lualaba, which he proved to be the Kongo by following it to the Atlantic Ocean, was a journey of unsurpassed courage, persistency, and resourcefulness. His return to found the Kongo State was followed by extensive discoveries, such as Lakes Leopold and Mantumba, the Ubangi, Kasai, and other affluents of the mighty river. Stanley's geographic laurels were increased by his search for Emin Pasha, when he crossed Africa from the junction of the Kongo and the Aruwini over the Bantu borderland. He discovered not only an extensive and almost impassable forest, but also the ultimate lake source of the White Nile, Albert Edward Nyanza.

Stanley's exploration of the Kongo. Basin was a potential force, second only

to that of Columbus' discovery of America. Each explorer opened up a new continent, and gave rise to scientific and philanthropic schemes which affected the progress of the world.

Europe awakened to the importance of the Kongo Basin, with its great lakes, its ten thousand miles of navigable rivers, which leave no part of the basin one hundred miles distant; its fertile valleys, its animal life and vegetable resources, and its millions of inhabitants. Africa speedily became the center of commercial exploitation, which was not confined to private enterprise. Most fortunately, by act of international conference the Kongo Free State, with an area of nearly a million square miles, became independent. Presenting the greatest natural possibilities, it practically bears, in interest and importance, the same relation to Africa as does the watershed of the Mississippi and its tributaries to the United States.

By rail and steamboat one now travels from the west coast, through the Kongo State, more than half way across Africa. Its revenue is counted by tens of millions of francs, its exports and imports increase steadily, and, apart from the 12,000,000 inhabitants of the French Kongo, it has a population of 30,000,000. The effect of the geographic evolution of Africa upon Europe may be estimated by the statement that Belgium, in its relations with the Kongo State, deals with a country whose area is one hundred times its own, and that of the 11,500,000 square miles of Africa all but 500,000 are European dependencies.

OCEANOGRAPHY A NEW ART

As to oceanography, a development of the nineteenth century, space only permits allusion to the work of Sigsbee, in the Gulf of Mexico; Carpenter, Thomson, and Norwegian savants in the North Atlantic, and Nares and Murray

in the Challenger expedition. The latter work, under Murray's exposition, has outlined the main features of the oceanic world for the twentieth century to explore and chart in detail.

As to the twentieth century, it should be noted that pioneer discoveries are yielding steadily to scientific explorations. Future work will trend toward the outlining of existent and possible relations between man and his geographic environment. In this sense

there remain numerous geographic problems whose satisfactory solution will tax many generations of scientific explorers. Such, for instance, are current investigations as to the acclimatization of Europeans in tropical Africa and the distribution of underground streams in the arid regions of Australia and the United States.

Reverting to pioneer discoveries, the twentieth century, despite unceasing efforts of this age, inherits an extensive legacy of unknown lands. Exploration for exploration's sake will for many years find ample scope in untraversed polar regions, Arctic and Antarctic, where the attainment of the Poles will continue to be largely the end in view.

Of unexplored areas West Australia. now presents the most extensive, its vast desert having been examined only here and there along routes hundreds of miles apart.

While North America has large, vaguely known districts only in Mexico and Central America, yet South America presents many fields of great promise to adventurous men. This is especially true of the eastern slopes of the Andes in Ecuador, Colombia, and Brazil. In the western half of the drainage basin of the Amazon exploration has touched. only the banks of navigable streams. Our knowledge is largely conjectural as to the extent and distribution of its forests and upland and of the existent conditions of its fauna, flora, and inhabit

ants.