and 6 m. E. of the source of the Zambezi, both streams running a parallel course northward for some 15 m. There is, however, no connexion between the Zambezi and Congo systems. The Lualaba, also known as Nzilo, which is the main stream of the Kamolondo, rises at an altitude of 4700 ft., in 26° 40′ E., just north of 12° S.—the watershed of the western head-streams of the Congo being everywhere north of that parallel. East of the Lualaba—between it and the Luapula—rises the river Lufira. With many windings the Lualaba and Lufira pursue a generally northerly direction, passing through the Mitumba range in deep gorges, their course being broken by rapids for 40 or 50 m. Below Konde Rapids in 9° 20′ S. the Lualaba is, however, free from obstructions. (Just above the last of the series of rapids it is joined by the Lubudi, a considerable river and the westernmost of the Kamolondo affluents.) Between the rapids named and 7° 40′ S. its valley is studded with a chain of small lakes and backwaters. The largest—Upemba—has channels communicating both with the Lualaba and the Lufira. In the rainy season the whole region becomes a marsh; various grasses, especially papyrus, form floating islands, and the conditions generally recall the sudd region of the Nile. In about 8° 20′ S. the Lualaba and Lufira unite in one of these marshy lakes—Kisale—through which there is a navigable channel. The river issuing from Lake Kisale is called Kamolondo; it has a width varying from 300 to 1000 ft. and an average depth of 10 ft. From Konde Rapids to those of Dia in 5° 20′—a distance of 300 m.—there is no interruption to navigation saving the floating masses of vegetation on Kisale at high water. The region watered by these western head-streams of the Congo includes Katanga and other districts, which are among the most fertile and densely populated in Belgian Congo.
The Upper Congo or Lualaba.—After the junction of the Luapula (Luvua) and the Lualaba (Kamolondo) the united stream, known as the Lualaba or Lualaba-Congo, and here over half a mile wide, pursues a N.N.W. course towards the equator. The Dia Rapids, already mentioned, are the first obstruction to navigation encountered. A mile or two lower down the Lualaba passes through a narrow gorge called the Porte d’Enfer. From this point as far north as 3° 10′ S. the course of the river is interrupted by falls and rapids, the chief being the rapids (in 3° 55′ S.) below the Arab settlement of Nyangwe and those at Sendwe in 3° 15′ S. In this part of its course the Congo becomes a majestic river, often over a mile wide, with flat wooded banks, the only real impediments to navigation between the Dia Rapids and Stanley Falls being those named. Between the junction of the two main upper branches, about 1700 ft. above the sea, and the first of the Stanley Falls (1520 ft.), the fall of the river is less than 200 ft., in a distance of 500 m. During the whole of this section the Lualaba receives the most of its tributaries from the east. Of these, the Lukuga connects Lake Tanganyika with the Congo system. The Lukuga (see Tanganyika) drains the mountainous country through which it passes, and also, intermittently, receives the overflow waters of Tanganyika. The outlet from the lake is sometimes clear, sometimes silted up. The Lukuga is much broken by rapids, falling 1000 ft. during its course of some 300 m. Farther north are a number of streams which drain the forest region between 4° S. and the equator, the Lubamba, the Elila or Lira, the Luindi and the Lowa being the most important. Their sources lie on an upland region west of the Albertine rift-valley. The Luindi in its middle course has a general width of 60 to 100 yds., but the Lowa is larger, receiving two important affluents, the Luvuto from the north and the Ozo which rises in the mountains at the N.W. end of Lake Kivu. The lower course of the Luindi is very tortuous.
Stanley Falls.—Stanley Falls, which mark the termination of the upper Congo, begin a few miles south of the equator. At this point the river forsakes the northerly course it has been pursuing and sweeps westward through the great equatorial basin. The falls consist of seven cataracts extending along a curve of the river for nearly 60 m. They are not of great height— the total fall is about 200 ft.—but they effectually prevent navigation between the waters above and those below except by canoes. The first five cataracts are near together; only 9 m. separate the first from the fifth. The sixth cataract is 22 m. lower down, and the seventh, the most formidable of all the cataracts, is 26 m. below the sixth. The fall, divided into two portions by an islet, is 800 yds. wide. The channel is narrowed at the foot of the fall to some 450 yds. by an island close to the left bank; on the right bank of the river is the island of Wane Rusari (2 m. long by ¼m. broad), separated from the mainland by a channel 30 yds. wide. The fall is only about 10 ft.; but the enormous mass of water, and the narrow limits to which it is suddenly contracted, make it much more imposing than many a far loftier cataract. Small rapids mark the course of the river for another 2 m.
The Middle Congo.—Below Stanley Falls the Congo is unbroken by rapids for 980 m., and is navigable throughout this distance all the year round. The river here makes a bold north-westerly curve, attaining its most northerly point (2° 13′ 50″ N.) at 22° 13′ E., and reaches the equator again after a course of 630 m. from the falls-the distance in a direct line being 472 m. For another 250 m. the river flows south-westerly, until at Stanley Pool the limit of inland navigation is reached. For the greater part of this section the Congo presents a lacustrine character. Immediately below the falls the river, from ½ to 1 m. broad, flows between low hills, which on the south give place to a swampy region, the river-bank marked by a ridge of clay and gravel. After receiving the waters of the Aruwimi—130 m. below the falls—the Congo broadens out to 4 or 5 m.; its banks, densely wooded, are uniformly low, and the surface of the water is studded with alluvial islands and innumerable sandbanks, rendering it impossible save at rare intervals to see from bank to bank. The velocity of the current decreases as the waters spread out, though there is always a channel from 4½ to 5 ft. deep. About 100 m. below the Aruwimi confluence the Loika or Itimbiri joins the main stream from the north, the Congo narrowing considerably here owing, it is supposed, to the matter deposited by the Loika. At two or three other places lower down, the river is contracted to 2½ or 2 m. as a result of a slight elevation in the ground, but for a distance of 500 m. no real hill is met with. On the southern curve of the horseshoe bend are