Rirers.—The great rivers of A. are the Nile, the Niger, the Zambesi, the Orange, the Congo, the Senegal and the Gambia. See articles NILE, NIGER, etc. The first of these is formed by the junction of two rivers—the White Nile (Bahr-el-Abiad) and the Blue Nile (Bahr-el-Asrak). The former has its sources in the great equatorial lakes, including those called the Victoria Nyanza and the Albert Nyanza,- skirts the eastern edge of Kordofan, and passes into Nubia, where it isjoined by the Blue Nile at Khartum, after the latter has broken through the highlands of Abyssinia. The single stream then sweeps circuitously through Nubia in a succession of cataracts, and descending into Egypt reaches the Medi terranean through the far-famed delta. The second of the great rivers, the Niger, Joliba or Quorra—for it goes by these and other names is different parts of its course—rises in the Kong mountains of Guinea, about 0° 25' n. lat., 9° 43 w. long., and flows first n.e. till it reaches Timbuctoo, where it bends e. for a short distance, and then descends in a s.e. direction into the gulf of Guinea. Its length is estimated at 2500 m., and its naviga bility has been ascertained for a distance of upwards of 400 m.; but its banks are very pestilential. Its principal tributary is the Tchadda or Benue. At the extreme w. of the mountains of Kong, and not far from the source of the Niger, rises the Senegal, which flows with a crescent sweep to the n.w. through Senegambia, and enters the Atlantic n. of cape Verd. The Gambia, a smaller river, runs in a similar direction, and falls into the sea s. of Cape Yard. The Congo, proved by Stanley to be identical with the river called at various parts of its course thjChambezi, Luapula, Lualaba, etc., runs northwards to a point about 2° n. of the equator, and thence s.w. towards its embouchure in the Atlantic at cape Padrone. Its whole course is about 2900 m. The Orange river flows w. with many windings through what is popularly termed " the country of the Hottentots;" while the Zambesi, explored almost throughout its entire course by Livingstone, is rich in affluents, and runs in an easterly direction, the channel of Mozambique about 18° s. lat.
Lakes.—The lakes of A. are, as yet, no better known to us than its rivers. Tchad, Chad, or more correctly, according to Dr. Barth, Tead, the chief lake of Sudan or central A., has a circumference of about 200 m., with a depth varying from 8 to 15 ft., and an eleva tion of 850 ft. above the sea-level. Though it has no outlet, its waters are cool and clear, and abound with fish. Besides a multitude of temporary streams, it is the recipient of several large rivers. The chief is the Shary or Asu, from the s.c. Dembea, or Tzaua, in Abyssinia, through which the Blue Nile flows, is about 65 in. long and 30 broad, and lies 6000 feet above the sea-level. Lake N'gami, in southern A., the center of the internal drainage of the country between the Orange and the Zambi, is about 2500 ft. above the sea-level, 70 in. long and 20 broad. N. of the Zambesi, between the parallels of 10° and 14° s., and about 350 in. inland from the coast of Mozambique, lies lake Nyassa, at an elevation of 1200 ft. above the sea-level. The discoveries of Tanganyika and the Vic toria Nyanza by Speke, and of the Albert Nyanza by Baker, have been already noticed, and will be found fully described in their proper place. It is now satisfactorily ascer tained that the source of the Nile lies in the basin of these lakes; but Livingstone was of a different opinion, and at his death was employed in exploring another basin some degrees westward of Tanganyika, the lakes in which (Bemba or Bangwcolo, Moero, and many smaller lakes) are now known to drain into the river Lualaba or Congo. In time of flood, Tanganyika also discharges into the Lualaba.
Geology.—The geology of A. is known as yet only from cursory observations made at isolated points. The character of the Sahara has been already indicated. The section traversed. by Dr. Livingstone presents a variety of schists, shales, sandstones, and tufa, through which protrude granite and trap-rocks. In one place towards the e. side of the continent, the sandstone is found overlying coal. Between Tripoli and Murzuk there is a plateau, the dark sandstone of which, disintegrated, fills up the inequalities of the sur face, from which the black rock stands out in fantastic cones. The lofty barrier of lime stone which forms the western boundary of Egypt, reappears in the rugged ranges of hills which break the monotonous waste of Sahara; they sometimes contain marine shells. Secondary limestone also constitutes the lower skirts of the Atlas mountains, but what are three great varieties of climate, corresponding to tie physical structure of the continent: 1st, that of the plateaus; 2nd, that of the terraces which lead to them; and 3d, that of the coasts. In the vast desert of Sahara, extending over an
area equal to that of the Mediterranean sea, almost destitute of water and vegetation, and partly covered with tracks of sand and bare low rocks, the heat of the day is uni formly contrasted with the coldness of the night; while on the terrace-land of Limbu, for instance, situated behind the Sierra Leone region, we find a temperate and whole some climate; and in that rising behind the slave coast we have beautiful landscapes, abundant springs, new forms of vegetation, and a mild Italian air. The natives of Congo call their terrace-lands, which are well cultivated and thickly peopled, " the par adise of the world." But the flat coasts, which are often overflooded in the rainy season, have a very oppressive atmosphere, and from the morasses at the mouth of the rivers a malaria arises which is pestilential to Europeans. This malaria has been supposed to arise from the decay of the vegetable matter brought down by the rivers from the dense mangrove woods, which, mixing with the salt water on the coast, produces sulphureted hydrogen gas. The region of pestilential air has been calculated to extend about 100 m. inland, but only 40 m. out at sea, and to rise to a height of 400 ft. above the sea-level.
Productions. —The vegetation of A. is decidedly less varied than that of Europe or Asia. Along the Mediterranean sea-board it greatly resembles that of southern Europe. The trop ical regions are not so rich in species of plants as those of S. America, but still they exhibit many peculiar genera. As we leave the sultry coasts and ascend the terraces towards the interior, we pass gradually from tropical productions to those of the temperate zones, which all flourish well in several parts of A. Though the forests cannot rival those of Brazil, they are rich in valuable woods, especially the harder kinds; some of them excel lent for ship-building. Here we find the gigantic adansonia (q. v.), digitata or baobab. Ebony, certain kinds of rosewood, and the timber called African teak, are among the productions of the tropical forests. The butter-tree (bassist, q.v.) is one of the most remarkable productions of the central regions. Extensive level tracts are covered with acacias. Certain palms are very characteristic Of different parts of A., and are of the greatest importance to the inhabitants, particularly the date-palm (q.v.) in the n., and in an inferior degree the doom-palm (q.v.), both of them growing in regions comparatively arid, and often surrounded by the very sands of the desert; whilst the oil-palm (q.v.) flourishes amidst the tropical 'luxuriance of the w. and supplies an article of commerce which now attracts the ships of Europe, in constantly increasing numbers, to shores once frequented only for the prosecution of the slave-trade. The cocoa-nut palm (q.v.) flour ishes on many parts of the tropical coasts. A large quantity of oil is produced also by a plant of a very different description, the ground-nut (aradii's, q.v.), a leguminous her baceous plant, which has the remarkable peculiarity of thrusting its pods into the ground to ripen there, and which is now so extensively cultivated that nine millions of bushels of ground-nuts are annually exported from the Gambia. The southern extremity of A. is remarkable for the vast number of its species of inesembryanthemums and heaths. Pelargoniums, iridacete and proteacew arc also among the most characteristic features of its vegetation. Euphorbiacese abound in most parts of the continent. Many of the productions of other countries have been introduced, both in the tropical and temperate parts of A. Maize is now extensively cultivated, as well as rice, wheat, and millet. A peculiar kind of grain, called fundi, or fundungi (paspalum t.rile), is cultivated in the west, and grains called tell and tocusso (poa Abyssinica and Eleusine tocusso) in Abyssinia. Coffee grows luxuriantly and of good quality. Indigo and tobacco arc easily cultivated, and cotton has succeeded well where it has been introduced, as in Egypt. where, how ever, it requires artificial and laborious irrigation; while in the rich and well-watered soil of Sennaar it flourishes even with a most careless style of cultivation, and might, without doubt, be produced in enormous quantity. Other regions, as Natal, seem likely soon to produce it abundantly.. The vine is cultivated with success at the cape of Good Hope, and the sugar-cane in different parts of the continent.