Page:Encyclopædia Britannica, Ninth Edition, v. 1.djvu/276

Rh 254 A F R I C A [PHYSICAL apart. Unlike the Nile, the Niger possesses one main channel through the centre of the delta, called at its mouth the Nun river. Old Calabar river, the Camaroon river, and the Gaboon, are the best known of a number of wide inlets or estuaries of the sea, which occur on the west coast immediately north of the equator; but these are merely the receptacles of a number of minor streams, not the mouths of great rivers, as at one time supposed. The Ogowai (pron. Ogowee) river, the delta of which forms Cape Lopez, irnmedaitely S. of the equator, is a great stream which is believed to drain a large area of the forest zone between the Niger and the Congo ; as yet, its lower coast is only known to a distance of 200 miles from the sea. Above the delta the main stream of the river, named the Okanda, breaks through the edge of the plateau, and is joined by the Onango, a tributary from the coast range of the Sierra Complida. Below this confluence the river is a mile and a half in average width, its depth varying from 15 to 50 feet. The delta is formed by the two main branches into which the Ogowai divides at about 30 miles from the coast, and is a swampy flat, covered with mangroves. Tho Congo or Zaire must be considered the second river of Africa in point of area of drainage, and it is the first in respect of the volume of water which it discharges to the ocean. There remains but little doubt that the head streams of this vast river are those which supply the great lacustrine system discovered by Dr Livingstone in his recent journeys south and west of Lake Tanganyika. Through these lakes the river, which rises in the upland north of Lake Nyassa. named in different parts of its course the Chambeze, Lua- pula, or Lualaba, flows in great bends to west and north ward, to where it passes into the unknown country still to be explored in the heart of the continent. The Lualaba has a great tributary named the Lufira, from the south; and it is almost certain that the Kassabi river, which springs in the Mossamba Mountains, in the interior borders of Angola, is also one of the feeders of this great river. The Quango river, rising in the same mountains, nearer Angola, must also join the Congo lower down in its valley. At the furthest point on the Lualaba reached by Living stone, in about lat. 6 S. and long. 25 E., the great river had a breadth of from 2000 to 6000 yards, and could not be forded at any season of the year. Every circum stance connected with this river its direction, the time of its annual rising, and the volume of its water which could be discharged by the Congo mouth alone point to its identity with this river. The explorer Tuckey, who, in 181 G, followed up the Congo from its mouth on the west coast further than any one, found it, above the cataracts which it forms in breaking through the coast range, to have a width of from 2 to 4 English miles, and with a current of from 2 to 3 miles an hour; and his statement that at the lowest stage of its waters it discharges 2,000,000 of cubic feet of water per second, has been confirmed by more recent surveys. Forty miles out from its mouth its waters are only partially mingled with that of the sea, and some nine miles from the coast they are still perfectly fresh. The Congo is the only one of the large African rivers which has any approach to an estuary, contrasting in this respect with those which have delta mouths. The Coanza, the most important river of Angola, in respect of its affording a navigable channel for 140 miles from its mouth, rises in a broad valley formed by the Mossamba Mountains in the interior of Benguela, and curves north-westward to the ocean. Its upper course is rapid, and its navigation only begins after the last of its cataracts has been passed; the mouth is closed by a bar. The Gunene river has its rise in the opposite watershed of the mountains, its springs being close to those of the Coanza, and its course is south- v cstward, forming the southern limit of the territory of Mossamedes. It is the most southerly river of the central fertile zones of Africa on this side of the continent, and appears to be suitable for navigation throughout the greater part of its length rising from 15 to 20 feet at times of flood, but having such a depth, at its lowest stage, as to be only passable by canoes. From the Cunene, in lat. 17 S., to the Orange river in 20 S., the dry belt of the South African desert zone intervenes, and there are no permanent rivers on the laud sloping to the sea. The coast lands from the edge of the plateau are, however, furrowed by numerous water-courses, which are filled only after the occasional rainfalls. The Orange river also belongs for the greater part of its Orang lower course to the water-courses of the arid belt, but it receives such a constant supply from its head streams, which descend from the high lands near the east coast of the continent, as to be able to maintain a perennial flow in its channel, which, however, is so shallow as to be of no value for navigation. Its main head streams are theVaal and Nu Gariep or Orange, which rise on the opposite slopes of one of the summits of the Drakenberg range, called the Mont aux Sources. After encircling the Orange River Free State, these rivers unite near the centre of this part of the continent to form the Orange, which continues west ward to the Atlantic, but without receiving any permanent tributary. The chief water channels which periodically carry supplies to it from the south are Bralc and the Great Hartebeeste; from the Kalahari region in the north come the Molopo and Nosob channels. Midway between the union of the head streams and the ocean the river forms a great fall of 150 feet in height. The rivers which flow down from the terraces of the Cape Colony are numerous, but have little permanent depth of water, shrinking almost to dry ness excepting after rains, when they become impetuous torrents ; some have cut deep channels, much beneath the level of the country, and the banks of these canons are choked with dense vegetation. Passing round to Natal and Zulu Land, the coast country is well watered by frequent streams which descend from the base of the cliff-wall of the Drakenberg ; these have gene rally the character of mountain torrents, with rapid flow between high banks and changing volume, and are almost without exception closed at their mouths by sand bars, which in most instances shut in considerable lagoons. One of these, the lake of Santa Lucia, js more than 40 miles in length. The first large river of the Indian Ocean system is the Limpopo or Crocodile river, so named from the great num ber of these animals found in its bed. Its basin lies centrally in the southern tropic, also in the desert belt, and on this account it barely maintains a shallow flow of water throughout the year. Its sources are in that part of the plateau edge in the Transvaal Republic which is known as the Hooge Veldt and Magalies Berg ; from this it forms a wide semicircular sweep to north-east and south, reaching the ocean not far north of Delagoa Bay, in 25 S. Its chief tributary, the Olifant or Lepalule, has its rise in a part of the Hooge Veldt which is nearer the coast. Many of its minor tributaries in its lower course are periodical streams known as sand rivers, only filled after heavy rains. The Zarnbeze is the great river of the pastoral belt of Zamb South Africa, and the fourth in point of size in the con tinent, draining nearly GOO.OOO scmare miles. As far as its basin has yet been explored, the Zambeze has three head streams from the great water-parting ridge which extends from the Mossamba Mountains of inner Angola to the high lands north of Nyassa Lake, about the 12th parallel of S. latitude. There are the Lungebuugo river from the Mossamba Mountains, the Leeba river from Lake Dilolo, on tho water-parting which separates be- Draiu to the Imliai Ocean Limp-