1911 Encyclopædia Britannica/Congo
CONGO, formerly known as Zaire, the largest of the rivers of Africa, exceeded in size among the rivers in the world by the Amazon only. The Congo, though it has a shorter course than the Nile, has a length of fully 3000 m. and a drainage area estimated at 1,425,000 sq. m., with a diameter of some 1400 m. either way. This vast area includes the equatorial basin of Central Africa and much of the surrounding plateaus. West and north the Congo basin is bounded by comparatively narrow bands of higher ground, while east and south the drainage area of the river includes considerable portions of the high plateaus of east and south Central Africa. The main drainage of the Congo system is thus north and west, and these two directions dominate the great bow-like sweep of the main stream before it is deflected south on approaching the western highlands, through which it finally forces a way to the Atlantic Ocean. From the high lands of the south and east in which the head-streams of the Congo have their origin, the land falls in a succession of steps, generally marked by gorges or rapids in the upper courses of the streams. Besides the main stream most of the affluents of the river are navigable for considerable distances; in all there are over 6000 m. of navigable water in the Congo basin and 20,000 m. of overhanging wooded banks. On the Congo alone are over 4000 islands, many of considerable length—some fifty of them are over ten miles long. The volume of water poured into the Atlantic is at least 1,200,000 cubic ft. per second.
Head-Streams.—The most distant head-streams of the Congo are far to the north and east of those most to the south, and it is difficult to determine which stream is the “parent” river. The easterly head-streams are, however, regarded generally as marking the true course of the Congo. The most remote of these rivers is the Chambezi, which, with its tributaries, rises (in British territory) on the southern slope of the plateau between lakes Nyasa and Tanganyika at an elevation of about 6000 ft. The watershed is formed by the crest of the plateau, and is perfectly distinguishable, save at a spot called Ikomba, about half-way between the lakes, where is a swamp which drains to both the Atlantic and the Indian oceans. The Chambezi source is in 9° 6′ S., 31° 20′ E. Its chief tributary, the Karungu, rises in 9° 50′ S., 33° 2′ E. The Chozi, an affluent of the Karungu, rises in the same latitude as the Chambezi, about half a degree to the east of that stream. After the junction of the Karungu and Chambezi the river flows in a south-westerly direction through a fairly fertile country, and receiving many tributaries becomes a large river with steep wooded banks and many islands. Its width varies greatly, from 30 yds. to 2 m. in a comparatively short distance; its depth is rarely less than 14 ft. In its lower course the Chambezi passes through papyrus marshes, and dividing into several channels, enters the vast swamp which forms the southern part of Lake Bangweulu (q.v.). The large river, known as the Luapula (Great River), which issues from Bangweulu in 11° 31′ S. and runs south through this swamp, may be regarded as a continuation of the Chambezi, there being a channel from the one stream to the other. The Luapula on leaving the swamp bends west and then south—reaching 12° 25′ S.—and approaches the watershed of the Zambezi, receiving several southern tributaries. The source of its most southern affluent, and therefore the most southern point in the Congo basin, is approximately in 13° 30′ S. Turning north the Luapula precipitates itself down the Mumbatuta (or Mambirima) Falls (12° 17′ S., 29° 15′ E.), the thunder of which can be heard on a still night for 8 or 9 m. The river, the width of which varies from 250 to 1200 yds., is almost unnavigable until below the Johnston Falls (Mambilima of the natives), a series of rapids extending from 11° 10′ to 10° 30′ S. Below the falls the river is navigable by steamer all the way to Lake Mweru—a distance of 100 m. Before entering Mweru (q.v.) the Luapula again passes through a swampy region of deltaic character, a great part of the water escaping eastwards by various channels, and after spreading over a wide area finally passing into Mweru by lagoon-like channels east of the main Luapula mouth. From Bangweulu to Mweru the fall of the river in a total distance of 350 m. is about 700 ft. The river (known now as the Luvua) makes its exit at the N.W. corner of the lake, and bending westwards in a winding course, passes, with many rapids, across the zone of the Kebara and Mugila mountains, falling during this interval nearly 1000 ft. In about 6° 45′ S., 26° 50′ E. it joins the Kamolondo (otherwise Lualaba), the western main branch of the Congo, which, as it flows in a broad level valley at a lower level than the eastern branch, is held by some to be the true head-stream. The Kamolondo is formed by the junction of several streams having their source on the northern slope of the south-central plateau as it dips towards the equatorial basin. This escarpment contains many heights exceeding 6000 ft. The streams flowing south from it belong to the Zambezi basin, but the watershed is not everywhere clearly defined. Thus the Lumpemba (an affluent of the Lokuleshe, one of the main tributaries of the Lubudi) rises in 11° 24′ S., 24° 28′ E., 3 m. S. 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 found the largest islands of the Congo—Esumba, 30 m. long, and Nsumba, 50 m. long, and over 5 across at its broadest part. At this point the river from bank to bank is 9 m. wide. Opposite Nsumba, the Mongala, a northern affluent, enters the main stream, whilst lower down (just north of the equator) the Lulanga, Ikelemba and Ruki rivers, southern tributaries, mingle their black waters with the dark current of the Congo. Thirty miles south of the equator the river is joined by the Ubangi (q.v.), its greatest northern affluent. Here the Congo is fully 8 m. wide. Opposite the Ubangi confluence is the mouth of a narrow channel, some 10 m. long, which connects the Congo with Lake Ntomba, a sheet of water about 23 m. long by 8 to 12 broad. In flood time the water flows from the Congo into the lake. Immediately below ferruginous conglomerate hills of slight eminence reduce the river to a width of less than 2 m., and in comparatively close succession are two or three other narrows. With these exceptions the Congo continues at a width of 5 to 6 m. until at 2° 36′ S. it abruptly contracts, being confined between steep-faced hills rising to 800 ft. This stretch of the river, known as the “Chenal,” is 125 m. long and is free from islands, though long reefs jut into the stream. Its width here varies from 2 m. to less than 1 m. About 40 m. after the Chenal is entered the Kasai (q.v.) coming from the south empties its brick-coloured waters at right angles into the Congo through a chasm in the hills 700 yds. wide. The confluence is known as the Kwa mouth. The Chenal ends in the lake-like expansion of Stanley Pool, 20 m. long by 14 broad. The middle of the pool is occupied by an island (Bamu) and numerous sandbanks. Its rim is “formed by sierras of peaked and picturesque mountains, ranging on the southern side from 1000 ft. to 3000 ft. in height.” The banks offer considerable variety in character. On the north bank are the Dover Cliffs, so named by H. M. Stanley from their white and glistening appearance, produced, however, not by chalk but by silver sand, the subsidence of which into the water renders approach to the bank sometimes dangerous. The banks of the lower end of the pool are comparatively flat. On the south side, however, stands the great red cliff of Kallina Point (about 50 ft. high), named after an Austrian lieutenant drowned there in 1882. Round the point rushes a strong current 7½ knots an hour, difficult to stem even for a steamer. On the northern bank of the river at the western end of the pool is the French port of Brazzaville. South of the pool hills, low but steep, reappear, and 4 m. lower down begin the cataracts which cut off the middle Congo from the sea. Some 300 yds. above the first of these cataracts is the Belgian port of Leopoldville, connected with the navigable waters of the lower river by railway. At Stanley Pool the elevation of the river above the sea is about 800 ft., a fall of over 500 ft. in the 980 m. from Stanley Falls. The banks of the river throughout this long stretch of country are very sparsely populated. The number of inhabitants in 1902 did not exceed 125,000.
The velocity of the stream in the middle Congo varies considerably. At the Aruwimi confluence the rate is from 300 to 350 ft. a minute; in the broader stretches lower down the current is not more than 200 ft. a minute. Through the Chenal the pace is greatly accelerated, and as it flows out of Stanley Pool the current is not less than 600 ft. a minute.
The Lower Congo.—The cataracts below Stanley Pool are caused by the river forcing its way through the mountains which run parallel to the western coast of the continent. The highlands (known as the Serro do Crystal) consist of two principal mountain zones with an intermediate zone of lower elevation. The passage of this intermediate zone is marked by a fairly navigable stretch of river extending from Manyanga to Isangila, a distance of 70 m., during which the only serious rapids are those of Chumbo and Itunzima, the latter in 13° 54′ E.; while above and below, rapids succeed each other at short intervals. Some eighteen main rapids or falls occur during the upper section (87 m.), in the course of which the level drops about 500 ft.; and about ten in the lower section (56 m.), during which the fall is about 300. The last rapid is a little above the port of Matadi, beyond which the river is navigable for large vessels to the sea, a distance of about 85 m. At Matadi the tall cliffs on either side sink away and the river widens out into an estuary with many mangrove-bordered creeks and forest-clad islands of a deltaic character. This estuary is traversed by a deep cañon, in which soundings of 900 ft. have been obtained. The mouth of the river is in 6° S. and 12° 20′ E. The cañon or gully is continued into the open sea for over 100 m., with depths as much as 4000 ft. below the general level of the sea floor. Just below Matadi, where the width of the river is about half a mile, depths of 276 and 360 ft. have been found, the current here running at from 4 to 8 knots, according to the season; while the difference in level between high and low water is 20-25 ft. The difference in level is not due to tidal action but is caused by the rainy or dry seasons, of which there are two each during the year. In the middle Congo May and November are the times of greatest flood; in the lower river the floods are somewhat later. At Stanley Pool the maximum rise of water is about 15 ft. The tides are felt as far as Boma, 49 m. from the mouth of the river, but the rise is there less than a foot; while at the mouth it is 6 ft. The cañon above mentioned is occupied by salt water, which is nearly motionless. Above it the fresh water runs with increasing velocity, but decreasing depth, so that just within the mouth of the river it is only a few feet deep.
The river at its mouth between Banana Point on the north and Sharks Point on the south is over 7 m. across. Banana Point (which grows no bananas) is the end of a long sandy peninsula, its highest spot not more than 6 ft. above high water; Sharks Point is bolder and shaped somewhat like a reaping-hook with the point turned inward, thus enfolding Diegos Bay. The current of the river is perceptible fully 30 m. out to sea, the brown waters of the Congo being distinguishable from the blue of the ocean.
Northern Tributary Rivers.—The various head-streams and affluents of the upper Congo have been already described. Below Stanley Pool numerous streams with courses of 100 or more miles drain the Crystal Mountains and join the Congo. They are unnavigable and comparatively unimportant. There remain to consider the affluents of the middle river. Of these the most important, the Ubangi on the north and the Kasai on the south, with their tributary streams, are noticed separately. In dealing with the other affluents of the Congo those entering the river on the right bank will be considered first.
The Lindi enters the Congo about 15 m. below Stanley Falls in 25° 4′ E. It rises in 1° N., 28° 30′ E., and flows W. in a tortuous course. Below the Lindi Falls in 1° 20′ N., 26° E. it is navigable, a distance of over 100 m. A mile or two above its confluence with the Congo it is joined by the Chopo, a more southerly and less important stream. The basins of these two rivers do not extend to the outer Congo watershed, but the next feeder, the great Aruwimi, rises, as the Ituri, in closing proximity to Albert Nyanza, flowing generally from east to west. It is formed of many branches, including the Nepoko from the north, and its upper basin extends over 2½° of latitude. The upper river, to about 27° E., is much broken by rapids, but apart from those of Yambuya in 24° 47′ the lower river is nearly free from obstructions. To Yambuya, the limit of navigation from the mouth of the Aruwimi, is a distance of over 90 m. The Aruwimi flows almost entirely through the great equatorial forest, which here seems to reach its maximum density. Its confluence with the Congo is in 1° 12′ N., 23° 38′ E. On its north bank just above the mouth is the station of Basoko. The next tributary, known as the Loika, Itimbiri or Lubi river, rises in about 26° E., and, flowing generally west, joins the Congo by two mouths, 22° 35′–46′ E. The Loika is navigable by steamers as far as the Lubi Falls, a distance of 150 m. The Mongala, the next great tributary to join the Congo, drains the country between the Loika to the east and the Ubangi to the west. It rises in about 3° N., 23° 20′ E., and flows in a somewhat similar curve (on a smaller scale) to that of the Ubangi. The Mongala is navigable for over 300 m., and gives access to a fertile rubber-producing region. The Mongala confluence is in 1° 53′ N., 19° 49′ E. Below the Ubangi confluence the Sanga, in 1° 12′ S., 16° 53′ E., joins the Congo. The Sanga rises in the north-west verge of the Congo basin and flows in a general north to south direction. Its lower course is tortuous, as it flows across level, often swampy, plains. The main northern branch rises in southern Adamawa in about 7° N ., 15° E. An almost equally large western branch, the Dscha (or Ngoko), rises in about 3° N., 13½ E., and after flowing W. for 100 m. makes a sudden bend S.E., joining the main stream in 1° 40′ N., 16° E. In its course it traverses a vast tract of uninhabited forest. The Sanga is navigable by steamers as far as the south-east corner of the German colony of Cameroon, a distance of 350 m. The Likuala and Alima, which join the Congo within 30 m. of the mouth of the Sanga, are much smaller streams. The Léfini (mouth in 2° 57′ S., 16° 14′ E.) is the last stream of any size to join the Congo above Stanley Pool.
Southern Tributaries.—The first of the southern tributaries of the middle Congo, the Lomami, enters the main stream in 0° 46′ N., 24° 16′ E. It has a length of over 700 m., rising in nearly 9° S. It flows S. to N., the greater part of its course being parallel to and from 40 to 150 m. west of the upper Congo. It is comparatively narrow and tortuous, but deep, with a strong current, and is hardly broken by rapids north of 4½° S. About 3° S. it traverses a region of swamps, which may have given rise to the reports once current of a great lake in this locality. For the last 200 m. it is navigable by steamers. Below the mouth of the Lomami there is a long stretch with no southern tributary, as the great plain within the Congo bend is drained by streams flowing in the same direction as the middle Congo-east to west. The Lulanga (or Lulongo), about 400 m. long, enters in 0° 40′ N., 18° 16′ E. Its northern branch approaches within 20 m. of the Congo in its upper course. The main branch of the Ruki or Juapa, which enters a little north of the equator in 18° 21′ E., has its rise between 24° and 25° E. and about 3° S., in the swampy region traversed by the Lomami. On account of the colour of its water it was named by H. M. Stanley the Black river. It is about 600 m. long and has two large southern tributaries. A few miles above the Ruki confluence the Ikelemba (some 150 m. in length) joins the Congo. The three rivers, Lulanga, Ikelemba and Ruki, and their sub-streams, have between them over 1000 m. of navigable waters. No rapids intercept their course.
Exploration.–Unlike the Nile there are no classic associations with the Congo. A single mention made of the Zaire by Camoens in the Lusiads exhausts its connexion with literature (up to the beginning of the 19th century), other than in little known and semi-fabulous accounts of the ancient kingdom of Congo. The mouth of the river was discovered by the Portuguese naval officer Diogo Cão or Cam either in 1482 or 1483. To mark the discovery and to claim the land for the Portuguese crown he erected a marble pillar on what is now called Sharks Point. Hence the river was first called Rio de Padrao (Pillar river). It soon, however, became known as Zaire (q.v.), a corruption of a native word meaning “river,” and subsequently as the Congo. In the three centuries succeeding Diogo Cao’s discovery strangely little was done to explore the river. At length the British Admiralty took action, and in 1816 dispatched Captain J. K. Tuckey, R.N., at the head of a well-equipped mission. The expedition was prompted by the suggestion that the Congo was identical with the Niger. So slight was the knowledge of the river at that time that the only chart with any pretension to accuracy did not mark it farther than 130 m. from the mouth, a state of affairs, in the opinion of the admiralty, “little creditable to those Europeans who for nearly three centuries have occupied various parts of the coast” near the river’s mouth. Captain Tuckey’s expedition reached the mouth of the Congo on the 6th of July 1816, and managed to push up stream as far as Isangila, beyond the lowest series of rapids; but sickness broke out, the commander and sixteen other Europeans died, and the expedition had to return. Captain Tuckey and several of his companions are buried on Prince’s Island, just above Boma, the point where the Congo widens into an estuary. A detailed survey of the first 25 m. of the river was effected in 1826 by the “Levin” and the “Barracouta” belonging to Captain (subsequently Vice-Admiral) W. F. W. Owen’s expedition; in 1857 Commander J. Hunt, of the “Alecto,” made an attempt to ascend the river. but only reached the cataracts. Captain, afterwards Sir Richard, Burton attained the same limit in 1863, and also proceeded inland as far as Banza Noki (São Salvador). In November 1872 an expedition under Lieutenant W. Grandy, R.N., was despatched from England for the purpose of advancing from the west coast to the relief of David Livingstone. So little was the Congo known, however, that Ambriz was chosen as the starting-point, and the expedition marched overland. After many vicissitudes Lieutenant Grandy had to retrace his steps. He reached, late in 1873, a point on the Congo below the cataracts and intended thence to push his way up stream. The death of Livingstone was soon afterwards reported; and in April 1874, just as Grandy was prepared to ascend the river, letters of recall brought the expedition to a close.
It was by working down from its source that the riddle of the Congo was finally solved. In 1868 David Livingstone traced the course of the Chambezi to Lake Bangweulu. In March 1871 he reached the town of Nyangwe on the Lualaba, and died (1873) whilst endeavouring to trace the head-streams of that river, which he believed to be the Nile. “I have no fancy,” he once said, “to be made into ‘black man’s pot’ for the sake of the Congo.” Livingstone’s views were not shared by the scientific world, and as early as 1872 geographers were able to affirm from Livingstone’s own reports that the great river system he had explored in the region north of the Zambezi must belong to the Congo and not to the Nile. Actual proof was lacking, and of the course of the main river there was absolute ignorance. But in October 1876, H. M. Stanley arrived at Nyangwe from Zanzibar and from that point navigated the river over 1600 m. to Isangila—“Tuckey’s Furthest”—reached in July 1877, thus demonstrating the identity of the Lualaba with the Zaire of the Portuguese. Stanley’s great journey marked an epoch in the history of Africa, politically and commercially as well as geographically. Of the many travellers who followed Stanley in the Congo basin none did more to add to the exact knowledge of the main river and its greatest tributaries—the Ubangi, the Kasai and the Lomami—than the Rev. George Grenfell (1849–1906) of the Baptist Missionary Society. The Aruwimi was partly explored by Stanley in 1887 in his last expedition in Africa, and was further examined by Grenfell in 1894 and 1902. The western head-streams were largely made known by the Belgians, Capt. C. Lemaire and A. Delacommune, the last-named also mapping the upper Lomami and the Lukuga. (See also Ubangi; Kasai; Livingstone and Stanley).
See H. M. Stanley, Through the Dark Continent, &c. (London, 1878); George Grenfell, Map of the River Congo, with Memorandum (London, 1902); Sir H. H. Johnston, George Grenfell and the Congo (2 vols., London, 1908); C. Lemaire, Mission scientifique du Ka-Tanga (Brussels, 1901–1908); 17 memoirs, No. 16 being the Journal de route; J. K. Tuckey, Narrative of an Expedition to explore the river Zaire, &c. (London, 1818); E. Behm, “Proofs of the Identity of the Lualaba with the Congo” (Proc. Roy. Geo. Soc. vol. xvii., London, 1873); Le Mouvement géographique (Brussels, weekly since 1884), and the geographical works mentioned in the bibliography of the Congo Free State. Grenfell’s map, scale 1⋅250,000, is of the river between Stanley Pool and Stanley Falls. For the lower river see H. Droogmans, Carte du Bas Congo, scale 1⋅100,000, and Notices sur le Bas Congo (Brussels, 1900–1902). (F. R. C.)
- Sir John Murray estimated the mean annual discharge of the Congo at 419.291 cub. m., making it in this respect only second to the Amazon (Scot. Geog. Mag., 1887). The annual rainfall of the basin he put at 1213.344 cub. m.