# The Earth and Its Inhabitants/Africa/Volume 1/Chapter 2

CHAPTER II.
the nile basin.
The River.
In the length of its course the Nile is one of the great rivers of the world, and by many of the tribes along its banks the earth is supposed to be divided into two parts by this mysterious stream, coiled like a snake round the globe and grasping its tail in its mouth. It certainly exceeds all the other rivers of the eastern hemisphere, not excepting the Yangtze-Kiang or the three great Siberian arteries. In this respect it even surpasses the Amazon itself, and probably yields to the Missouri-Mississippi alone. Yet the chief river falling into the Victoria Nyanza, and thus forming the true upper course of the Nile, has not yet been determined with absolute certainty. It may even be larger than has been supposed, so that calculating from its farthest source south of the equator, the African river may possibly be superior in length to its North American rival. But taking it from the Nyanza alone, it is at least 3,750 miles long, and in a straight line along the meridian from lake to sea the distance is thirty-one and a half degrees of latitude, or about 2,100 miles. But to reach the farthest headstreams of the Nile basin we ​should perhaps descend over five degrees to the south of the equator and two to the east of the emissary from the great lake. The winding of its bed lengthens its whole course by over three-fourths.
In superficial area the Nile basin is inferior both to the Amazon and the Mississippi, and apparently about equal to the Congo. Except in its middle course, between the Makrara territory and Abyssinia, the lateral river valleys are of slight extent, and owing to the arid character of most of its basin, it cannot compare in volume to any of the other great rivers of the world. According to recent estimates, the Atrato, which falls into the Carribean Sea near the Isthmus of Panama, has a greater discharge, although its basin is nearly a hundred times smaller than that of the Nile.
The general tilt of the land from the central plateaux to the shores of the Mediterranean coincides with the Nile Valley. Nevertheless to its main fluvial arteries the whole of this region is exclusively indebted for its geographical unity. The lacustrine uplands of the interior, the marshy tracts where its chief affluents join the White Nile from the south-west, the isolated Abyssinian highlands, the Kordofan uplands encircled by solitudes, the Nubian deserts, the narrow winding valley of Upper Egypt, lastly the smiling plains through which the main stream ramifies as it approaches the Mediterranean, are all so many distinct geographical domains, which must have had a purely local development but for the unity imparted to them by the hydrographic system of the Nile. Thanks to the facilities for communication afforded by this great water highway, its lower reaches were peopled by Nubian colonies from remote times; the old Egyptian culture advanced up to Meroe, and even farther south; frequent wars were waged between the Ethiopians and the lowlanders for tilie command of the stream; and for centuries Egyptian viceroys have made incessant efforts to extend their possessions to the whole of the Upper Nile basin as far as the equatorial lakes and the "Great Divide." Along this main highway of North-East Africa the natural divisions between the riverain populations are marked by the obstructing cataracts and the confluences of the great affluents. Hence the study of the stream to which the surrounding lands owe their historic evolution claims our first attention.
The ancients asserted that the Nile had its source in the "Mountains of the Moon," and it is noteworthy that the southernmost affluents of the lacustrine system whence it escapes were met by Speke in the "Land of the Moon." But amongst these affluents is there one copious and large enough to be regarded as the main upper stream? This "head of the Nile" is still being sought, and as in the time of Lucan, no one can yet boast of having seen the farthest source of the Nile. According to the maps prepared from the itineraries of Stanley, Smith, Pearson, and the French missionaries, the Mwaru (Liwumba, Luwambé), which rises beyond the fifth degree of southern latitude, and flows north and north-west towards the ​Nyanza, would appear to bo the true "Nile of the Moon," at least in the length of its course. But if the barometric altitudes taken by Pearson can be trusted, this stream cannot possibly reach the lacustrine basin, for it flows at a lower level. On the other hand, it cannot trend westwards in the direction of Lake Tanganyka, from which it is separated by ridges some 500 feet high. Hence it probably runs out in some landlocked basin.
Speke was infonned by the natives that this region, comprised between the great lake and the lofty coast ranges, is studded with lakes and salines, like those heard of by Denhardt, Erhard, and Wakefield as lying further north. Till recently copious streams might still be supposed to flow from the western slope of Kilima-Njaro, the giant of African mountains, whose two snowy peaks rise some 240 miles to the east of Nyanza. But the waters escaping from the gorges of this volcano flow mainly east and south to the Indian Ocean, while the rivulets descending from its west side lose themselves in the depressions of the plateau. None of the watercourses observed by Stanley and other travellers on the east side of Nyanza are of considerable size, and all of them rise at some distance from Kilima-Njaro.
The water-parting between the Indian Ocean and the Nile is lower than the eastern ranges, and has rather the appearance of an elevated cliff terminating abruptly eastwards, and sloping gently towards the west. Above it at intervals rise volcanic cones, and the statement of the Arabs, that several of them still show signs of activity, has been recently confirmed by the evidence of the traveller Fischer. Erruptions are even said to occur, and two of the cones take the name of Dunyé-M'buro, or "Smoky Mountain." Another is known as the Dunyé-Ngai, or "Heavenly Mountain," and copious thermal streams flow from the fissures. The foot of the eastern escarpments, some 4,320 feet high, is skirted by a thennal lake, which is continued by swampy tracts where soda is deposited. In this district the chain of volcanoes is separated by a deep depression from Kilima-Njaro, and the lake itself is little over 2,000 feet above sea-level.
Of all the affluents of Lake Nyanza, the Kagera (Tanguré or river of Kitangulé), which joins it from the west, has the best claim to be considered as the main head-stream of the basin, at least so far as regards its volume. This river, which by its first explorers was named the Alexandra Nile, rises in a highland region some 60 miles south of the equator, and nearly 2,340 miles in a straight line from the Mediterranean. After collecting the torrents from Mount Mfumbiro it takes a normal north-easterly course towards Nyanza. Stanley penetrated into the valley of this Upper Nile below its confluence with the emissary of Lake Akanyaru, which had also received the name of Lake Alexandra even before it had been actually visited by any European. In the district explored by Stanley the Kagera traverses several lakes and receives the overflow from other lacustrine basins, flooding the surrounding depressions. It has a mean depth of fifty feet, and the horizon is completely shut out by the tall masses of papyrus fringing its banks. Speke and Grant, who were the first to visit this Upper Nile, crossed it much lower down, below the Morongo Fall, one or two days' march from its confluence with Nyanza.
​The Kagera is evidently a very copious stream, which during the rainy season overflows its banks for several miles, in a way that reminded Grant of the Hugli between Calcutta and Chandernagor. When Speke crossed it in January, 1862, that is, at low water, it was only 250 feet wide; but here it resembled a canal cut through dense masses of reeds, and was too deep for the boatmen to employ their poles. Its current is very rapid, running at least 3½ miles an hour and at its mouth forming a large estuary over 430 feet wide, and varying in depth from 80 to 130 feet. For several miles from the shore its dark grey stream continues to flow in a separate channel without intermingling with the blue waters of the lake.
The natives have a great veneration for their river, and one of the titles they give it seems to justify the hypothesis that it is really the main headstream of the Nile. According to Stanley they call it the "mother" of the "Stony Current," that is, of the emissary of Lake Nyanza in Uganda. At its north-west angle the lake is joined by the Kalonga, another copious river rising in the west in the neighbourhood of Lake Mwutan-Nzigé. Although it has a course of over 120 miles, its volume is certainly inferior to that of the Kagera.
Lake Victoria Nyanza.
The Nyanza, that is "lake" in a pre-eminent sense, known also as the Ukerewe, and now as the Victoria Nyanza, is the largest lacustrine basin in Africa. According to Stanley's provisional map, which will soon be superseded by the more matured work of Mackay, it is exceeded in superficial area only by one other lake—Superior, in North America. Both Michigan and Huron are smaller by several thousand square miles; and Aral itself, although generally designated by the name of "Sea," appears to yield in extent to Nyanza.
In the depth of its waters also this vast basin rivals the great lacustrine cavities of the world. In the immediate neighbourhood of the east coast, and close to some islands and islets, the sounding line recorded a depth of 590 feet, which may probably be exceeded in the middle of the lake. Should this prove to be the case, Nyanza will take the first place amongst fresh-water basins for the volume of its liquid contents. Its altitude above the sea has been variously estimated by different observers, but 4,000 feet has been provisionally adopted as not far from the truth.
By Speke, who discovered it in 1858, this great inland sea has been named the Victoria Nyanza, in honour of the Queen of England. But every tribe along its shores gives it a different name, while the Swaheli of Zanzibar know it as the Bahari-ya-Pila, or "Second Sea." Many other names also occur in history which evidently have reference to this sheet of water. The title of Kerewe is taken from Ukerewe, the largest island on the south coast, which is separated from the mainland by the narrow strait of Rugeshi, a mere ditch almost completely choked by ​the papyrus and other aquatic plants. But according to Wilson the most general appelation is simply Nyanza, that is, the "lake" in a superlative sense.
South of Ukerewe a large bay penetrating far inland has by Stanley been named after Speke, his precursor in the exploration of equatorial Africa. The stagnant pools and lagoons fringing this inlet are infested by crocodiles of enormous size. Others, which frequent the reedy banks of the Tanguré, are by the natives regarded as demi-gods, personifying the tutelar deity of the stream. Some of the islands are in the undisputed possession of fierce hippopotami, grouped in regular tribes and families, which tolerate the presence of no other large animals in their respective territories. For the capture of these monsters the natives have constructed boats of a peculiar build; but such hunting expeditions are always attended with great risk.
Fig. 10.—Sources of the Nile and Nyanza Plateau. Scale 1:7,300,000
The coastlands, which apart from a thousand small indentations have a circumference of over 720 miles, present an endless variety of landscape. Along the rocky shores the prevailing formations are everywhere gneiss, granite, or basalts. But in some places the riverain tracts spread out in level, treeless plains, while elsewhere the margin of the lake is skirted by high hills and even mountains diversified with patches of verdure and enlivened by groups of villages. Between ​the Kalonga and Tanguré rivers the coast is generally low, and here the shallow water nowhere exceeds a few feet in depth for two or three miles from the land. But farther south the shore is fringed by bare cliffs, varied with strips of red or orange lichens, giving them the appearance of blocks of iron, and several have in fact been found to consist of ferruginous ores.
The most charming prospects are displayed towards the north-west in the territory of U-Ganda. Here the inlets along the coast appear to be divided by the intervening wooded headlands into lakelets of unequal size. Limpid streams are everywhere seen sparkling amid the dense masses of verdure; down every dell flows a silvery rivulet fringed with tall grasses or shrubs, above which are interlaced the branches of forest trees. Probably no other region in Central Africa enjoys a more equable climate or a richer soil than this land of U-Ganda. The plants of the temperate zone recently introduced by Europeans thrive well.
Off the coast of U-Ganda an archipelago of four hundred islands, of which the largest group bears the name of Sessé, stretches in a continuous chain between the high sea and the creeks along the shore. The scenery of this insular world is even more diversified and its vegetation more exuberant than on the opposite mainland. Here magnificent timber clothes the slopes of the hills down to the beach, which is everywhere bordered by masses of papyrus. Towards the west the basalt island of Bukerebé, Stanley's Alice Island, raises its blackish walls over 300 feet above the lake. But of all the insular masses lining the shores of Nyanza, the most remarkable is that to which Stanley has given the name of "Bridge Island." This rock, which lies not far from the north-east corner of the lake, consists of two basaltic columns connected by an irregular elliptical arch with a spring of about twenty-four and a depth of twelve feet. Trees have struck their roots deep into the interstices of the rocks, which, overgrown with brushwood and tall grass, leave nothing visible except two columnar masses of verdure hanging in graceful festoons down to the water. Through this archway of tropical vegetation a glimpse is afforded of the hazy coast-range bounding the horizon on the opposite mainland.
The beauty of the Nyanza scenery is enhanced by the native craft which enliven its waters, and which are at times grouped in large fleets. Some of the surrounding communities have sailing-boats; the traders have launched vessels of considerable size, resembling the dhows of the Zanzibari Arabs, and the European missionaries have constructed sloops on the English model. But most of the skiffs are still of a primitive type, mere barges with round stems sunk deep in the water, and sharp prows projecting clean above the surface and adorned with two antelope horns and a bunch of feathers. From a distance they present the appearance of an animal raising its neck above the water in search of prey. These boats, manned by crews of from ten to forty-eight hands, carry neither mast nor sail, and are propelled only by the paddle. Rudely constructed of trunks of trees lashed together with flexible branches, and caulked with a mixture of bark and mud, they offer but a slight resistance to the waves; hence accidents are frequent, although they seldom venture far from the shore.
VIEW OF VICTORIA NYANZA—TAKEN FROM MURCHISON BAY.
The superfluous waters of the inland sea flow gently through a broad opening on the north coast over against the island of U-Vuma. This emissary, forming the head of the Nile properly so called, gradually narrows its banks to the proportions of a river, when its liquid contents are precipitated over a tremendous cascade, to which Speke has given the name of the Ripon Falls. A group of boulders, on which a few trees have taken root, stands nearly in the centre of the stream, which is here about 1,300 feet broad. Other less elevated blocks divide the current right and left, which lower down is studded with other reefs and rocks scarcely rising above the surface of the seething waters. Hence the expression Jinja, or "Stones," applied by the natives to these falls. Although they have a vertical height of 13 feet, hundreds of fishes crowding the lower reach are able to leap the rapids and pass to the upper stream, which a short distance higher up is gentle enough to be crossed by a ferry. Here the view of the lake is to a great extent concealed by a wooded headland, while the line of separation between the gulf and the course of the river is marked by a low peninsula crowned with a clump of palms. The hills of the mainland merge farther on in the verdant isles of the lake.
The Somerset Nile.
According to Stanley, the Kivira, as the Nile is here called, is about a third larger than the Tanguré, the chief affluent of Nyanza. It flows with a mean breadth of 550 yards, at first towards the north-west, and after passing a few smaller rapids, spreads out right and left in vast reedy lagoons. But even here its normal depth is maintained, and some 60 miles below the falls it enters the Gita-Nzigé, another lake, to which the name of Ibrahim has been given by Chaillé-Long, who discovered it in 1875. Compared with the other equatorial basins, it is of small extent, having an area of probably not more than 200 square miles. In this region the Nile receives a number of tributaries, including the Luajerri, which ​rises in the U-Ganda hills near the shores of Nyanza, and which was supposed by Speke to flow from the lake itself. On his map he sketched a third emissary, the Kafu, which after a course of about 120 miles joined the Nile lower down. But such a phenomenon as three rivers flowing from the same lake and meeting again after traversing a hilly region would indeed be remarkable. In point of fact the Kafu, like the Luajerri, rises not in, but near the lake, with which it has no communication.
Soon after leaving Lake Ibrahim the Nile is described by Chaillé-Long as again expanding into a vast morass covered with vegetation, and with a mean depth of scarcely more than 10 or 12 feet. This is the Kioja or Kapeki lagoon, which was discovered by the Italian explorer Piaggia, and a short distance below which the Nile is joined by the navigable river Kafu. Farther on it describes a bend towards the east and north, after which it trends abruptly westwards to its confluence with the great lake Mwútan-Nzigé, or Albert Nyanza. Throughout this section of its course the Nile is usually designated on English maps by the name of Somerset.
The river, which has here a mean breadth of over 1,300 feet, would be perfectly navigable but for its precipitous incline. According to the approximate measurements taken by travellers, the total fall in this distance of about 90 miles appears to be 2,310 feet, or about 1 in 205 feet. The Kuruma, the first fall occurring in this part of the Nile, is rather a rapid, where the water, confined between walls of syenite, escapes in sheets of foam down a total incline of about 10 feet. But this is followed by the Tada, Nakoni, Assaka, Kadia, Wadé, and Ketutu Falls, forming the chief barriers to the Nile on its descent from the high plateaux. In a space of 18 miles it passes from gorge to gorge, rushing over rocky boulders, filling the atmosphere with vapours, which are precipitated as rain on the trees lining its banks. The action of the stream has, so to say, sawn through its stony walls, while gradually lowering its level. On the south bank the cliffs rise to a vertical height of from 140 to 160 feet above the boiling waters.
This boisterous course of the Somerset Nile terminates in a magnificent fall. For about 12 miles above it, the bed of the river is so steep that rapids follow in quick succession, with a mean incline of at least 10 in 1,000 yards. Suddenly the current, contracted to a width of scarcely more than 160 feet, is precipitated over a ledge between two black cliffs, plunging from a height of 115 feet into a cauldron of seething waters, above which floats an iridescent haze quivering in the breeze. Some 300 feet above the ever-restless flood the cliffs are fringed with the waving branches of the feathery palm. To this cataract Baker, its discoverer, gave the name of the Murchison Falls, in honour of the learned president of the English Geographical Society. Almost immediately below its last eddies the water becomes quite still, expanding to a breadth of from 500 to 800 feet without any perceptible current, and resembling a backwater of Lake Albert Nyanza rather than the continuation of a rapid stream. This phenomenon is said to be due to a lateral affluent flowing north-west to the Lower Nile without traversing the lake, and constituting the real main stream.
Lake Albert Nyanza.
The lake discovered by Baker, and by him named the Albert Nyanza, is known to the people on its east bank aa the Mwútan-Nzigé, or "Grasshopper Sea." Others call it the "Great Water," although far inferior in extent to the Victoria Nvanza. It stretches south-west and north-east for a distance of about 90 miles, with a mean breadth of over 18 miles. According to Mason's rough survey it has a superficial area of 1,850 square miles, and stands at an altitude of 2,300 feet. From the Victoria to this lower basin the Nile has consequently descended nearly half of the entire elevation of the continent between the plateaux and the Mediterranean. Like the Dead Sea, the Mwútan-Nzigé seems to fill a fissure in the earth's crust. It is enclosed right and left by steep mountains, whereas at its northern and southern extremities it terminates in gently shoaling bays and low-lying beaches. The high cliffs on the east side, consisting of granite, gneiss, and red porphyry, form a first stage in the ascent towards the U-Nyoro and U-Ganda plateaux. The streams flowing from the swamps on these uplands have not yet completed their work of erosion by furrowing regular channels across the outer scarps of the plateau. Hence, like the Nile at Murchison Falls, they have all still to make their way through cataracts, where the volume of water is less but the fall much greater, being approximately estimated for most of them at about 320 feet.
Livingstone and other explorers of Central Africa supposed that Lake Tanganyka belonged to the Nile basin, sending its overflow north-eastwards to the Albert Nyanza. But subsequent investigation has shown that the two lakes have no conmiimication with each other. During their trips round the latter, both Gessi and Mason ascertained that from the south it receives no affluent except a shallow, sluggish stream, almost choked with vegetation. In this marshy district it is covered with a floating or half-submerged forest of ambach (arabaj), a leguminous plant (herminiera elaphrorylou), 18 or 20 feet high, with star-shaped leaves and golden yellow flowers like those of the broom. Its wood, which resembles cork in appearance, is the lightest known to botanists, so light that a raft strong enough to support eight persons forms the load of a single porter. It grows so densely that the native boats are unable to penetrate the tangled masses of vegetation springing from the muddy bottom of the lake. Beyond this aquatic forest Gessi beheld a vast prairie rolling away between two steep mountains, which formed a southern continuation of the coast ranges.
Lake Albert, continually renewed by contributions from the Nile, is everywhere sweet and pure, except in the southern shallows, where the water is turbid and brackish, and in some places on the east side, where it mingles with saline springs, utilised by the people of U-Nyoro. Although no distinct undercurrents have been observed, the navigation is rendered very dangerous by the sudden squalls sweeping round the headlands and down the mountain gorges. When embarking on their frail craft the natives never fail to cast some valued object into the lake as a propitiatory offering to the water-gods. A chief, one of Baker's friends. ​obtained from him a quantity of glass trinkets for the purpose of insuring the stranger's safety by employing them in this way. But since those first visits Lake Albert, already temporarily annexed to the Khedive's possessions, has been navigated in every direction by two steamers, which to pass the Nile cataracts had to be taken to pieces and put together again above the last portages. The transport of the Khedive required no less than 4,800 hands, of which 600 were needed to haul the boiler across the swamps, through the woods, and over the hills. The escarpments along the east coast are far more elevated than those on the opposite side.
It is sometimes asserted that the Nile traverses Lake Albert without mingling with the surrounding waters. But recent inquiry has shown that such is not the case. According to the varying temperatures, the warmer fluvial current spreads in a thin layer over the surface of the lake, gradually blending with it under the influence of the winds. But when the stream is colder it descends to the lower depths of the lacustrine cavity, where it replaces the lighter fluid. Hence, although the inflow is distant scarcely 12 miles from the outflow, the Somerset Nile becomes lost in the great lake, whose superfluous waters must be regarded as the main feeder of the emissary.
The White Nile.
This emissary, variously known as the Kir, the Meri, the Bahr-el-Jebel, or "Mountain River," and by other names according to the dialects of the riverain populations, flows normally north and north-east in a tranquil stream winding at a width of from 2,000 to 6,500 feet between its verdant banks. In the middle of the channel the depth varies from 16 to 40 feet, so that throughout the year it is accessible to large vessels for 120 miles below the lake. The shores are fringed with wooded islands and islets, while large masses of tangled vegetation drift with the current, especially at the beginning of the floods. These floating islands consist of a substratum of decomposed foliage and reeds strong enough to support an upper layer of living vegetation, by whose roots and tendrils the whole mass becomes solidly matted together. Daring the course of five or six years the flora becomes renewed, the surface growth decomposing in its turn, and causing the aquatic garden to break up and float away in smaller sections with the stream. But it often happens that the vegetable refuse accumulates in sufficiently large quantities to enable these floating islands to strike root here and there in the bed of the stream, and in the Nile basin whole rivers have sometimes been covered with such buoyant masses, firm enough to bear even the weight of caravans. Owing to the rapid development of this rank vegetation, the Nile has frequently been choked in its upper reaches and compelled to cut new channels in the surrounding alluvia. On the plains stretching west of the present Nile traces are seen in many places of these old beds, or "false rivers," as they are called. The low chain of hills skirting this plain on the west, and forming the water-parting between the Nile and Congo basins, might not inaptly be named the "Explorers' Range." The crests following ​from south to north bear the names of Schweinfurth, Junker, Chippendall, Speke, Emin, Baker, Gordon, and Gessi.
The great bend described by the Nile below the Dufli station, at an elevation of about 2,100 feet above the sea, marks a very important point in the hydrography of its basin. Here it is joined by several copious affluents, including the Asua or Asha, supposed by some geographers to flow from Lake Mbaringo (Baringo, Bahr Ingo), which Speke at one time identified with a north-east inlet of Victoria Nyanza, and whose very existence has since been questioned. But the question has been practically settled by Thomson, who visited the district in 1884, and who determined the existence of Baringo and another large lake farther south.
The Asua, however, rises not in a lake, but in a hilly region east of the Somerset Nile, while the Mbaringo is a landlocked basin without any outflow. At their junction both the Nile and the Asua, skirted right and left by hills, are obstructed by reefs, and even above the confluence the navigation of the main stream is completely obstructed by the Fola Rapids, which Wilson has named the "Eighth" Cataract. Here all vessels on the Upper Nile have to stop and tranship their cargoes, an inconvenience which has caused the Nile route to be almost abandoned above the rapids. After leaving the bend at Dufli, caravans for Victoria Nyanza strike south-eastwards, rejoining the Somerset Nile at Foweira, above the Karuma Kapids. This route, which has also been taken by the recent military expeditions from Egypt, is twice as short as that by the winding valley of the river.
Below the Asua confluence the Nile is still obstructed here and there by rocky ledges, as at Yerbora, where it rushes between huge boulders, at Makedo, where it develops two falls over six feet high, and at Teremo-Garbo and Jenkoli-Garbo, where other rapids occur. But all of these impediments may be passed during the floods. Steamers freely ascend for nine months in the year as far as Ragat or Rejaf, and to the winding at Bedden below the falls forming the "Seventh" Cataract. But during low water they are unable to get beyond the famous station of Gondokoro, or Ismailiya, which was long the capital of Upper Egyptian Sudan. The head of the navigation for large vessels is indicated by the sandstone eminence of Rejaf, a perfectly regular cone of volcanic appearance terminating in a tower-shaped rock, which rises over 330 feet above the surrounding plain.
At this point the Nile, according to the estimates of Dovyak and Peney, has a normal discharge of about 20,000 cubic feet, oscillating between 10,000 at low and 30,000 at high water. During the floods it presents an imposing appearance at Gondokoro and Lado (Lardo), the new capital of the province of the equator. But flowing through an almost level plain, it soon ramifies into numerous lateral channels, while other secondary streams, intermingled with marshes and lagoons, wind right and left of the Bahr-el-Jebel, or Kir, as this section of the Nile is called by the Dinkas. The main stream itself branches off completely, the Nile proper continuing its north-westerly course, while the Bahr-ez-Zaraf, or "Giraffe River," winds for 180 miles through swamps and prairies northwards to a point where the two branches again unite. The Zaraf is described by Marno not as a ​river in the proper sense, but merely a khor or watercourse, which is becoming yearly less navigable, and already inaccessible to boats except for a short time during the floods. The whole low-lying region at present intersected by the Bahr-el-Jebel, the Zaraf and all their countless affluents, channels, and branches was evidently at one time a vast lake, that has been gradually filled up by the alluvia of these rivers. Its northern margin is indicated by the abrupt change in the course of the Nile at the confluence of the Bahr-el-Ghazal, or "Gazelle River." At this point the whole system of waters is collected in a single channel, which is deflected eastwards along the escarpment of the upland Kordofan plains. A cavity of the old depression is still flooded by a remnant of the lake called the No, Nu, or Birket-el-Ghazal, which, however, under the action of the currents and periodical floods, is continually overflowing its marshy banks, shifting its place and modifying its outlines. Fig. 11—From Dufilé to Lado. Scale 1 : 1,500,000. Nowhere else is the Nile more obstructed by vegetable refuse as along this section of its course. The floating islands drifting with the current being arrested by the abrupt winding of the stream are collected together, and stretch at some points right across the channel, which thus becomes displaced. But the new channel is soon blocked by fresh masses of sedd, as it is called, which in many places covers a space of twelve miles. This sedd often acquires great consistency, supporting a dense growth of papyrus, and even of arborescent vegetation, beneath which the main stream continues its sluggish course. Numerous families of the Nuer tribe pitch their tents on the verdant surface, living exclusively on fish caught by piercing the foundations of their dwellings, and on the grain of various species of nymphæaceæ. In certain places along the banks of the river and surrounding swamps are seen myriads of earth-mounds, all raised above the highest level of the inundations by their architects, the termites, who ascend and descend from story to story with the flowing and ebbing stream. One of the most ​remarkable inhabitants of this watery region is the balœniceps rex, a curious long-legged aquatic bird with grey plumage, which when perched on a termite's hillock looks from a distance like a Nuer fisherman.
Fig. 12.—Region of the "Sud." Scale 1 : 2,000,000. From the time when the envoys of Nero failed to penetrate the sea of floating vegetation, explorers of the Nile have been frequently arrested by this obstacle. During the latter half of the present century most of them have had to force their way through the tangled masses, and one of the channels thus formed by Miss Tinne's steamer still bears the name of Maya Signora. During the seven years from 1870 to 1877 the river was completely blocked, obliging all travellers to continue their journey by the Bahr-ez-Zaraf. Many were detained for weeks and months on these pestiferous waters, over which hover dense clouds of mosquitoes. Here Gessi was arrested in 1880 with five hundred soldiers and a large number of liberated slaves, and three months elapsed before an Egyptian flotilla, under Marno, was able to rescue them by opening a passage from below. Devoured by the insects, wasted by fever, and reduced to live on wild herbs and the dead bodies of their unfortunate comrades, most of the captives found a grave in the surrounding swamps, and nearly all the survivors perished of exhaustion soon after. Gessi himself outlived the disaster only a few months. To the lagoon of No must be attributed those "green waters" noticed at Cairo during the early days of June, when the stream, charged with vegetable ​cellules, acquires a marshy taste and becomes unwholesome. But all this refuse is swept away or destroyed by the first floods from the Abyssinian rivers, which thus restore to the Nile water its excellent properties.
The "Gazelle," which joins the main stream in the No basin, is a "bahr," that is, a considerable river, flowing from the west, and during the floods bringing sufficient water to sweep away the temporary obstructions. In its channel are collected a hundred other rivers, whose numbers and copiousness form a striking contrast to the poverty or total absence of running waters characteristic of the Nile basin farther north. Altogether the affluents of the great river are distributed
Fig. 13.—The Nile at Khartum.
GENERAL VIEW OF KHARTUM.
​down very little water, and none at all for the rest of the year. Unique in this respect among the great rivers of the globe, the Nile seems for the greater part of its course to be a river destitute of tributary basins. On its west bank nothing occurs for 2,200 miles from its mouth except some wadics flushed during the ruins.
But then follows a sudden and remarkable contrast, due to the changed climatic conditions. All the triangular region comprised between the Bahr-el-Jebel, the Nile, and Congo water-parting, and the Dar-For uplands, is intersected by numerous perennial streams nearly converging in the direction of the old lacustrine basin now filled with alluvia and vegetable refuse. With their minor headstreams and affluents they form a vast and intricate hydrographic system, extremely difficult accurately to survey, especially owing to the varied and shifting nomenclature. Like the Nile itself, every secondary branch bears as many names as there are tribes in its valley or neighbourhood. The most important appear to be the Yei, which is lost in the swamps bordering the left bank of the Nile; the Rol, flowing to the Bahr-el-Ghazal; the Roa and Tonj, whose united waters form the Apabu; the Diur, which reaches the Bahr-el-Ghazal near Meshra-er-Rek, and which is the most copious of its many affluents; the Pango, a branch of the Diur; lastly the Famikam, better known as the Bahr-el-Arab, which forms the northern limit of the whole region, and which, after its junction with the Ghazal, deflects the Nile eastwards.
Most of these streams have a very gentle incline, the most rapid being those that take their rise in the mountains near lake Albert Nyanza. Some have their source altogether in the plains, offering an almost imperceptible transition to the basin of the Congo. In their lower course the Rol, Diur, and some others have too slight a fall to scour their beds of the vegetation constantly accumulating. The consequence is that, like the Nile, they overflow their banks, during the floods converting the whole country for some thousiinds of square miles into an impassable morass. A large portion of the rainfall in this part of the Nile basin evaporates before reaching the main stream. Here the annual rains represent a volume greater than the whole discharge of the Nile at Cairo.
At the point where it resumes its normal northerly course beyond the region of sedd, the Nile is joined on its east bank by the Sobat, which is also known by a great variety of names. The Sobat, which drains a very large area, and which ​Russegger mistook for the Nile itself, is the first affluent that receives any contributions from the Ethiopian highlands. It frequently sends down a greater volume than the main stream, whose waters during the floods are stemmed and driven back by its current. To judge from its whitish fluid contents, in which the blackish Nile water disappears, the Sobat has the best claim to the title of Bahr-el-Abiad, or "White River." Some of its affluents rise on the low-lying plains stretching east of the Nile; but the most important has its source much farther east, in the upland valleys of the Ghesha range, which forms the water-parting between the Indian Ocean and Mediterranean basins. The Baro, which is one of the dozen different names of this affluent, on entering the plain traverses the
Fig. 14.—Meshra-er-Rek in the Zareba Region. Scale 1:2,200,000.
marshy Lake Behair of the Arabs, or "Sea of Haarlem," as it has been renamed by the Dutch explorer Schuver. During the rainy season the Sobat sends down a vast quantity of water, on June 15, 1862, estimated by Pruyssenaere, 70 miles above the confluence, at 42,000 cubic feet per second. Hence during the floods the whole of its lower course is easily navigated; but if large craft linger too long on its treacherous flood they run the risk of being landed high and dry on some shifting sandbank, as happened to the trader Andrea Debono, who was recently detained in the river for eleven months.
It is below the Sobat that the Nile takes currently the Arab name of Bahr-el-Abiad, or "White River," by which it is generally known to Europeans above ​Khartum, where it is joined by the other Nile, called the Bahr-el-Azraq, or "Blue River." The contrast is certainly striking between the two currents, the former being charged with organic remains, turbid, and muddy, while the latter, flowing from a rocky region, is generally much more limpid. But a greater contrast is presented by the variations in their respective volumes according to the seasons. The western branch, which is by far the longest, the distance from Khartum to its still undetermined source being even greater than from that place to the Mediterranean, has also the most uniform discharge. Regulated by the great equatorial lakes, and again by the swampy depressions about Lake No, its contents present comparatively less discrepancies from season to season. But the impetuous Bahr-el-Azraq partakes rather of the nature of a torrent. As soon as the tropical downpours begin to fall on the Abyssinian plateaux, the effect is felt in its rocky channel. Then its discharge exceeds that of its rival, and it was on this ground that Bruce and many subsequent explorers claimed the first rank for the Abyssinian branch. But since the discoveries of Speke, Grant and Baker, it can be regarded only as an important tributary of the Bahr-el-Abiad. Its mean volume is less considerable, nor is it navigable at low water.
The Blue Nile.
On the other hand, if it is the White Nile that maintains the perennial stream, to the Blue Nile is due its fertilising properties. Without the first there would be no Egypt; but for the second the soil of this region would lack its inexhaustible fertility. Not only do the Abyssinians send down their quickening waters to the Nile delta, but they also supply it with the sedimentary matter by which the land is incessantly renewed, and the never-failing return of bountiful harvests insured. In the Ethiopian highlands is solved the mystery of the Egyptian stream, yearly overflowing its banks without apparent cause, and then retiring to its bed after accomplishing its beneficent work. It is to be regretted that the discharge of both rivers has not been accurately determined, the Nilometer at Khartum serving to estimate that of the Blue Nile alone.
At the confluence we at once enter regions known to the ancients. The Bahr-el-Azraq is the Astapus of Ptolemy, whose source was possibly known to the Romans. At least they make it rise in a lake, the Coloe Palus, although placing this lake some twelve degrees south of its actual position. Lake Tana (Tsana) is regarded as the reservoir giving rise to the Abai, which is usually taken as the upper course of the Blue Nile. But if length of course alone be taken into consideration, this honour should rather be awarded to the Beshto, which has its origin some 150 miles farther east. The Tana emissary, however, has the advantage of being much more constant in its discharge, thanks to the controlling action of the ​lake, which rises slowly during the floods, and falls imperceptibly during the dry season. The yearly discrepancy between the levels of the lake scarcely exceeds forty inches.
The Abai, its largest affluent, rises at Gish Abai, near the north-east foot of Mount Denguiya, some 60 miles from the lake. The Portuguese colony settled in this region towards the end of the sixteenth century certainly visited the sources of the Abai; but they were first described by the Jesuit Paez, who tells us that the water, oozing from a marshy field, is collected in a limpid lake, supposed by the natives to be "unfathomable" because they cannot reach the bottom with their spears. Thence trickles a rivulet, whose course can be traced only by a surface growth of waving grasses, but which over a mile lower down emerges in the open. This is the brook to which both the Portuguese and Bruce gave the name of the Nile. The fiery exhalations often seen flitting about its source, doubtless will-o'the-wisps, have earned for the Abai the veneration of the natives, who still sacrifice animals to the local river genius. The stream has a width of over 30 feet where it reaches the south-west inlet of the lake, and where its turbid waters have developed an alluvial delta of considerable size. But the outlet, which retains the name of Abai, is a limpid blue current fully entitled to its Arabic designation of Bahr-el-Azraq. Like most other rivers which are at once affluents and emissaries of lacustrine basins, the Abai is constantly said to traverse lake Tsana without mingling with its water. But although such a phenomenon is well-nigh impossible, a perceptible current certainly appears to set steadily from the mouth of the affluent to that of the outflow.
THE NILE AT THE SECOND CATARACT.
COLOSSAL STATUES OF MEMNON.
BANKS OF THE NILE—THE SHADUF.
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* ↑ Length of the Missouri-Mississippi 4,230 miles. ""Nile, with the Nyanza headstream 4,200" ""Amazon, with the Apurimac 3,600" ""Irtish-Ob 3,410" ""Selenga-Angara-Yenisei 3,300" ""Vitim-Lena 3,280" ""Yangtse-Kiang 2,790"
* ↑ Approximate area of the great river basins:— Amazon 2,800,000 square miles. Mississippi 1,390,000"" Nile 1,340,000"" Congo 1,280,000""
* ↑ E. G. Ravenstein, "Map of Eastern Equatorial Africa."
* ↑ Area of the chief lakes of the world:—Superior, 33,500 square miles; Nyanza, 26,600; Aral, 26,300; Huron, 24,500; Michigan, 23.600; Erie, 11,300.
* ↑ Nomenclature of the Upper Nile and its affluents:— Nile: Kivira, Somemet (between lakes Victoria and Albert); Meri (in the Madi country); Karré (by the Ban people); Kir (by the Denkus); Yer (by the Nuer); Bahr-el-Jebel (by the Arabs between Lakes Albert and No); Bahr-el-Abiad, or "White River" (by the Arabs below the Sobat). Yei: Ayi, Doghurguru, Jemid, Rodi, Bahr-Lau. Rol: Nam-Pol, Ferial, Welli, Yabo, Nam-Gel. Roa: Meriddi, Bahr-jau. Tonj: Tondy, Leesi, Doiggoru, Kuan. Diur: Heré, Nyenam, Bahr-Wau, Ugul, Relaba. Pango: Ji, Dishi, Ugakaer, Bahr-el-Homr. Famikam: Bahr-el-Arab, Lialui, Lol, Lollo, Komkom. Sobat: Bahr-el-Mogaté, Waik, Telfiu, Wah, or Tah (by the Shiluks), Pinyin, or Tilfi (by the Nuer), Biel, Kieti, Kidi, or Kiradid (by the Dinkas).
* ↑ Approximate estimate of the discharge of the two Niles at Khartum per second:— Bahr-el-Abiad. Bahr-el-Azraq. High water  ••  175,000 cubic feet. High water  ••  213,000 cubic feet. Low water  ••  10,000 cubic„ feet.„ Low water  ••  5,500 cubic„ feet.„