Page:Encyclopædia Britannica, Ninth Edition, v. 1.djvu/275

Rh FEATURES.] AFRICA 253 Livingstone, in the lake region of Central Africa, have so narrowed the space within which the sources of the Nile can exist, that, though no traveller has yet reached the ultimate feeders of the great river, their position can now be predicated almost with certainty. The limit of the Nile basin on the south is formed by the high mountains which rise to westward of the Albert Lake, and which divide between this great reservoir and the Tanganyika, extend ing eastward to the plateau of Unyamuezi, on the northern side of which the Victoria Nyanza lies. The ultimate sources must then be the feeders of these great equatorial lakes, the Victoria and Albert. The river issuing from the former lake, at the Ripon Falls, 3300 feet above the sea, to join the northern end of the Albert Nyanza, may be considered as the first appearance of the Nile as a river. At the Ripon Falls the overflow is from 400 to 500 feet in breadth, and the descent of 12 feet is broken in three places by rocks. Further down, where the river turns westward to join the Albert Lake, it forms the Karurna and Murchison Falls, the latter being 120 feet in height. From the Albert Lake, the Nile, called the Kir in this part, begins its almost due northward course to the Mediterranean, and has no further lake expansion. Be tween the Albert and Gondokoro, in 5 N. lat., which lies at 2000 feet above the sea, the Nile descends at least 500 feet in a series of rapids and cataracts. Beyond Gondokoro, up to which point it is navigable, it enters the northern lower land of Africa, which is here a region of swamps and forests, and several tributaries join it from the west. The largest of these, named the Bahr-el-Ghazal, unites with the main stream below the 10th parallel; and, not much further on, a main tributary, the Sobat river, joins the Nile from the unknown region which lies to the south east. Hence, onward, the Nile is known as the Bahr-el- Abiad or White River. The two remaining great tribu tary rivers descend from the high land of Abyssinia on the cast. The first of these, the Bahr-el-Azrek or Blue River, its waters being pure in comparison with those of the Nile, has its source near Lake Dembea or Tzana, through which it flows, in the western side of the Abyssinian plateau, 6000 feet above the sea ; forming a semicircular curve in the plateau, the Blue Nile runs north-westward to the confluence at Khartum, 1345 feet above the sea. Between this point and the union of the next tributary, the Nile forms the cataract which is known as the sixth from its mouth. In about 18 N. it is joined by the Atbara or Black River, the head stream of which is the Takkazze, flowing in a deep cut valley of the high land. This tribu tary is named from the dark mud which it carries from the high land, brought down to it by streams which swell into rushing torrents in the rainy season. It is to these rivers that the fertility of Lower Egypt is mainly due, for each year a vast quantity of Abyssinian mud is borne down to be spread over the delta. Hence the Nile pursues its way in a single line through the dry belt of desert to the Mediterranean without a single tributary, descending by five cataracts, at considerable distances apart. The delta of the Nile, in which the river divides into two main branches, from which a multitude of canals are drawn off, is a wide low plain, occupying an area of about 9000 square miles. The most remarkable circumstance connected with the delta is the annual rise and overflow of the river, which takes place with the greatest regularity in time and equality in amount, beginning at the end of June, and subsiding completely before the end of November, leaving over the whole delta a layer of rich fertilising slime. The Sheliff in Algeria, and the Muluya in Eastern Marocco, are the chief streams flowing to the Mediterranean fr m the Mgh land f Barbar y- Passing round to the Atlantic system, the Sebu, the Ummer Rebia, and the Tensift, from the Atlas range, are permanent rivers flowing across the fertile plain of Western Marocco, which they serve to irrigate. Next is the Wady Draa, a water-course which has its rise on the inner slope of the high land in Marocco, and which bends round through the Maroccan Sahara to the Atlantic, near the 28th parallel. Its channel, of not less than 500 miles in length, forms a long oasis in the partly desert country through which it flows, and water remains in its bed nearly throughout the year. A stretch of 1100 miles of waterless coast, where the desert belt touches on the Atlantic, intervenes between the Draa and the Senegal river, at the beginning of the pastoral belt in lat. 15 N. The Senegal rises in the northern portion of the belt of Seneg: mountains which skirt the Guinea coast, and has a north westerly course to the sea. During the rainy season it is navigable for 500 miles, from its mouth to the cataract of Feloo, for vessels drawing 12 feet of water, but at other times it is not passable for more than a third part of this distance. The Gambia has its sources near those of the Gamb Senegal, and floAvs westward in a tortuous bed over the plain country, giving a navigable channel of 400 miles, up to the Falls of Barra Ivunda. The Rio Grande, from the same heights, is also a considerable river. The Niger is the third African river in point of area Niger, of drainage and volume ; it is formed by the union of two great tributaries, the Quorra and Benue, the former from the west, the latter from the country in the east of the river basin. The Quorra, called the Joliba in its upper course, has its springs in the inner slope of the mountains which give rise to the Senegal and Gambia, not far from the Atlantic coast. At first its course is north-eastward to as far as the city of Timbuctu, on the border of the desert zone ; then it turns due east, and afterwards south-east to its confluence with the Benue, at a point 200 miles north from the coast of the Gulf of Guinea. The chief tributary of the Quorra is the Sokoto river, coming from the elevated country which forms the water-parting between the Niger basin and that of Lake Chad on the east, and its confluence is near the middle of the portion of the channel of the Quorra which bends to south-east. At a distance of about 100 miles from its sources, the traveller Park, the first European who reached the Joliba, found it flowing in a wide fertile valley, and navigated by canoes which kept up a constant traffic. Above Tirnbuc- tu the commerce of the river is busily carried on in barges of 60 to 80 tons burden; further on, where the river touches upon the desert belt in the most northerly portion of its course, its fertile banks form the most marked con trast to the arid desert lands beyond. From the confluence of the Sokoto to the union with the Benue, the river course is only navigable after the rainy season, since at other times rocks and shoals interrupt the passage. The sources of the Benue are unknown as yet, but it is believed to have its rise in the northern edge of the great plateau of Southern Africa, almost due south of Lake Chad; its known course is westward, and at the furthest point to which it was easily navigated by the traveller Baikie, nearly 400 miles from its confluence with the Kawara or Quorra, it was still half a mile in width and about 10 feet in average depth, flow ing through rich plains. From the confluence of the Quorra and Benue the Niger has a due south course to its delta, and the united river has an average width of about a mile. At a distance of 100 miles from the sea, minor branches which enclose the delta separate from the main stream on each side. The delta is much more extensive than that of the Nile, and measures about 14,000 square miles of low alluvial plain, covered with forest and jungle, and com pletely intersected by branches from the main river, the outmost of which reach the sea not less than 200 miles