27 CHAPTER IV. DISTRIBUTION OF THE WATERS OF THE GLOBE.-OCEAN.INLAND SEAS.LAKES.-RIVERS.--SPRINGS. Turn to the watery world.-CRABBE. ALTHOUGH, for the convenience of description, the ocean has received several nominal subdivisions, yet, correctly speaking, the different seas and oceans are but parts of one mighty whole, one "capacious bed of waters." O, thou vast ocean! ever-sounding sea! Thy voice is like the thunder; and thy sleep Is as a giant's! slumber loud and deep. Thou speakest in the east and west At once. The two principal divisions of the ocean, the Atlantic and the Pacific, are formed by the extension from north to south of the two great continents. The Austral, or Southern Ocean, may be considered as forming a third division, and occupies that portion of the ocean not included in the two former. Its limits may be marked by a line passing round the globe, and touching the Cape of Good Hope, Cape Horn, and the southern extremity of Tasmania, or Van Diemen's Land. The Atlantic Ocean is sometimes subdivided into three portions-the Northern Ocean, the North Atlantic, and the South Atlantic. The imaginary separation between the Northern Ocean and the North Atlantic, is marked by a line drawn across the ocean, from the southern extremity of the British Isles, to the southern extremity of Greenland. The North Atlantic extends from thence to the equator; and the South Atlantic from the equator to the southern extremities of Africa and America. The Pacific Ocean has also three nominal subdivisions, the North and South Pacific, and the Indian Ocean. The North Pacific extends from Behring's Straits to the equator, and the South Pacific from thence to Cape Horn and the southern side of Australia. The Indian Ocean comprehends the seas between Australia and the Malayan Islands, and the eastern coast of Africa. Its separation from the Austral, or Southern Ocean, is merely nominal. With these oceans, various seas communicate, either by narrow straits, as the Mediterranean, the Red Sea, and the Baltic; or by wider channels, as the White Sea, the Yellow Sea, Baffin's Bay, &c. Besides these seas, all of which have an outlet into the main ocean, and most of which penetrate to a considerable extent into the land, we meet with other seas which are wholly inland. Such are the Sea of Aral, and the Caspian Sea. These, however, though denominated seas, have many of the characteristics of lakes; and perhaps it would not be easy to define the difference between an inland sea and a lake. If size be considered to form the distinction, the lakes of North America will doubtless be entitled to rank as seas; if saltness, the lakes of Van, in Armenia, and of Ourmia, in Persia, with many others of smaller size, are entitled to this distinction. The most celebrated European lakes are those of Constance and Geneva. The Russian lakes, of which Ladoga is the largest, are, however, of much greater extent. The British lakes, though presenting much picturesque scenery, are of small size; the largest English lakes, those of Westmoreland and Cumberland, would appear as mere specks on a map of Europe. The lakes of Scotland, of which Loch Lomond is the largest, though of somewhat greater extent, are insignificant in a general view of the world. The lakes of Ireland are likewise of small dimensions; but the Lake of Killarney and Lough Erne are celebrated for their beautiful and picturesque scenery. Asia contains some fresh-water lakes, among which is that of Baikal, but the greater number of its lakes are salt. The most celebrated of the latter is Lake Asphaltites, or the Dead Sea, which is more saline than the ocean. Many of these natural depositories of salt are situated in the interior of this vast region, and their occurrence in districts so far removed from the sea, is of great importance to the inhabitants, who, in many cases, obtain considerable supplies of that valuable article, merely by collecting the saline encrustations formed round the margin of the lakes. We are too little acquainted with the interior of Africa, to speak with any certainty as to the number or character of its lakes; but the Lake Tchad is described as one of the largest fresh-water lakes in the world. North America, however, may be considered as the country of lakes. A vast chain, more or less connected with each other, extends across a large portion of the continent, commencing near the shores of the Arctic Ocean, and terminating on those of the Atlantic. Many of these lakes are of great extent, but the most remarkable are those which form the great water system of Canada. The largest of these is Lake Superior, which has an extreme length of 380 miles, and a breadth of 161 miles. The surface occupied by the lakes Superior, Michigan, and Huron, is computed at 72,930 square miles. South America is very deficient in lakes; that of Titicaca, before alluded to, being the only considerable one in this portion of the New World. This lake, however, is remarkable on account of its great elevation above the level of the sea. The size and course of rivers is mainly determined by the height and direction of the mountain ranges, or hilly districts, in which they take their rise; and also by the extent of surface between their sources and the sea. A reference to Plate III. will show that the longest known rivers in the world are those of North and South America. The largest rivers of Europe, the Rhine, the Rhone, and the Danube, take their rise in the Alps. When mountain ranges form the separation between two countries, the boundary is not unfrequently marked by the course the rivers take, which is called the water-shed. Thus, in the Pyrenees, the direction of the streams flowing either north or south, marks the limits of the two kingdoms of France and Spain. The majestic rivers of Asia, the Ganges, the Indus or Scind, the Irawaddy, and the Brahmapootra, have their sources in the Himalayan range. The rivers of China, also, take their rise in the continuation of the same vast line of mountains. The northern rivers of Asia, the Irtish, the Obi, and the Yenesei, all originate in the Altai mountains. In Africa, the Nile has one of its sources among the lofty mountains of Abyssinia, and the other in the more distant central range. Respecting the sources of the other principal rivers of Africa, there is still much obscurity. In North America, the Arkansas, the Red River, and the Missouri, all tributaries of the Mississippi, take their rise in the Rocky Mountains. In the same great range, we also meet in close connexion, the sources of the river Colombia, and of the Saskatchewan; the former of which, taking a westerly course, falls into the Pacific; whilst the latter, flowing in an opposite or easterly direction, enters Lake Winnepeg, and passing through the vast chain of lakes, of which the St. Lawrence forms the outlet, finally falls into the Atlantic Ocean. In South America, the majestic Marañon, or river of the Amazons, the Oronooko, the Magdalena, and other vast rivers, spring from the mighty range of the Andes. The Parana and the Paraguay take their rise in a range of less elevation, which stretches across the continent to the coast of Brazil. When the sources of rivers lie among mountains, they are subject to sudden descents, which give rise to rapids, cascades, and cataracts. Rapids are caused by the greater slope or inclination of the bed of a river, which causes the water to rush down in that particular part, sometimes with fearful velocity. Cascades and cataracts are formed by water precipitating itself from a ledge or mass of rock, with a perpendicular, or nearly perpendicular, descent. When in their most impetuous character, they are denominated cataracts; when more gentle, they are termed cascades. Although England may not boast of any waterfalls that can vie with those of countries of more mountainous character, it nevertheless possesses some cascades of considerable beauty. Cumberland, Westmoreland, Durham, Yorkshire, and Devonshire, present many instances of picturesque waterfalls. One of the most beautiful in this country is the fall of the Tees, in Durham. The river, obstructed and divided by a mass of rock, descends in a double cataract from the top; but reuniting its waters before they reach the bottom, the whole dashes into the basin with a force and grandeur scarcely inferior to the cataracts of Switzerland, or even America. The falls of the Cayne and the Mawddach, in Merionethshire, called Pistil-y-Cayne and Pistil-y-Mawddach, are highly picturesque. The former is described as particu |