The article proves hypsometrically that the Lualaba, in which the explorer found the head waters of the Egyptian river, cannot feed the Tanganyika nor the Lake Nzige (N'zíghe, Mwutan, Chowambe, or Albert Nyanza Lake), nor even the Bahr el Ghazal, as was once suspected. From the latter, indeed, it is barred by the water parting of the Welle, the "Babura" of Jules Poncet (1860), in the land of the Monbuttú; whose system the later explorer, Dr. Schweinfurth, is disposed to connect with the Shari. Hydrometrically considered, the Lualaba, which at Nyangwe, the most northerly point explored by Dr. Livingstone (1870), rolls a flood of 124,000 cubic feet per second in the dry season, cannot be connected either with the Welle (5,100 cubic feet), nor with the Bahr el Ghazal (3,042 to 6,500 cubic feet), nor with the Nile below the mouth of the Bahr el Ghazal (11,330); nor with the Shari (67,500); nor with the shallow Ogobe, through its main forks the Rembo Okanda and the Rembo Nguye.
But the Lualaba may issue through the Congo. The former is made one of the four streams ferried over by those travelling from the Cazembe to the Mwata ya Nvo, and Dr. de Lacarda[22] records it as the "Guarava," probably a dialectic form of Lualava. It is the Luapula of the "Geographer of N'yassi," who, with his usual felicity and boldness of conjecture (p. 38), bends it eastward, and discharges it into his mythical Central Sea.
Dr. Behm greatly under-estimates the Congo when he assigns to it only 1,800,000 cubic feet per second. He makes the great artery begin to rise in November instead of September and decrease in April, without noticing the March-June freshets, reported by all the natives to measure about one-third of the autumnal floods. His elements are taken from Tuckey, who found off the "Diamond Rock" a velocity of 3.50 knots an hour, and from Vidal's Chart, showing 9,000 English feet or 1.50 nautical miles in a Thalweg fifty fathoms deep. Thus he assumes only two nautical miles for the current, or sixty inches per second, which must be considerably increased, and an average depth of ten fathoms, which again is too little. For 1,800,000 cubic feet of water per second, which Tuckey made 2,000,000, we may safely read 2,500,000.
Dr. Livingstone himself was haunted by the idea that he was exploring the Upper Congo, not the Nile. From a Portuguese subordinate he "learned that the Luapula went to Angola." He asks with some truth, "Who would care to risk being put into a cannibal pot, and be converted into blackman for anything less than the grand old Nile?" And the late Sir Roderick I. Murchison, whose geographical forecasts were sometimes remarkable, suspected long ago[23] that his "illustrious friend" would follow the drainage of the country to the western coast.
The "extraordinary quiet rise of the periodical flood," proved by the first expedition, argues that the Congo "issues from the gradual overflowing of a lake or a chain of lakes." The increment in the lower bed, only eight to twelve feet where the Nile and the Ganges rise thirty and the Binuwe fifty, would also suggest that it is provided with many large reservoirs. The Introduction to Tuckey's "Narrative" (p. xviii.) assumes that the highest water is in March, but he entered the stream only on July 6, and the expedition ended in mid-October. The best informants assured me that from March till June there are heavy freshets. As in the Ogobe, the flood begins in early September, somewhat preceding that of the Lualaba, but, unlike the former stream, it attains its highest in November and December, and it gradually subsides from the end of June till August, about which time the water is lowest.
In the middle region of the Tanganyika, I found the rainy season lasting from September to May. At Lake Liemba, the south-eastern projection of the Tanganyika, Dr. Livingstone in 1867 saw no rain from May 12 to September, and in Many-wema-land, west of the central Tanganyika, about south latitude 5°, the wet season began in November, and continued till July with intervals, marking the passage of the belt of calms. But, for the Congo to rise in September, we must assume the rains to have fallen in early August, allowing ten or fifteen days for the streams to descend, and the rest for the saturation of the land. This postulates a supply from the Central African regions far north of the equator. Even for the March-June freshets, we must also undoubtedly go north of the Line, yet Herr H. Kiepert[24] places the northernmost influent of Congo some 150 miles south of the equator. Under these limitations I agree with Dr. Behm:—"Taking everything into consideration, in the present state of our knowledge, there is the strongest probability that the Lualaba is the head stream of the Congo, and the absolute certainty that it has no connection with the Nile or any other river (system) of the northern hemisphere." And again: "As surely as the sun stands over the southern hemisphere in our winter and the northern in our summer, bringing the rains and the swellings of the tropical rivers when it is in the zenith with regard to them, so surely can it be predicated, from a comparison of the rainy seasons and times of rising, that the Lualaba belongs to no river of the northern hemisphere; in the southern hemisphere Africa possesses only one river, the Congo, which could take up the vast water supply of the Lualaba." The Brazil shows the curious feature of widely different and even opposite rainy seasons in the same parallel of latitude; but this is not the place to discuss the subject.
Since these lines were written, I have to lament the collapse of the Livingstone-Congo Expedition. In 1872 the great explorer's friends, taking into consideration the prospect of his turning westward, organized a "relief" from West as well as from East Africa. Mr. J. Young, of Kelly, generously supplied the sinews of travel, and Mr. Clements R. Markham, Secretary of the Royal Geographical Society, lent important aid in preparing the exploration. Navigating-Lieutenant W. J. Grandy, who had seen service on the eastern coast of Africa, landed at S. Paulo de Loanda in early 1873, and set out from Ambriz in March of that year. The usual difficulties were met and overcome, when Lieutenant Grandy was summarily recalled. The official explanation ("Royal Geographical Society," December 14th, 1874), is that the measure was in consequence of Livingstone's death. The traveller himself says:—"Complying with instructions, we, with many regrets at the idea of leaving our work unfinished when all seemed so full of promise, commenced preparations for the return, leaving good presents with the chiefs, in order to procure a good reception for those who might come after us." An Ex-President of the Royal Geographical Society had asserted, "The ascent of the (Upper) Congo ought to be more productive of useful geographical results than any other branch of African exploration, as it will bring to the test of experiment the navigability of the Congo above the Falls, and thus possibly open out a means of introducing traffic by steam into the heart of the continent at least two thousand miles from the mouth of the river."
With this explicit and stimulating assertion before us, we must lament that England, once the worthy rival in exploration of Spain, Portugal, and the Netherlands, is now too poor to support a single exploration on the West African Coast, when Germany is wealthy enough liberally to subsidize two.
Note.
A nous deux, Dr. E. Behm!
My objections to your paper are the three following: 1. It generally understates the volume of the Nzadi, by not allowing sufficiently for the double equinoctial periods of high water, March to June, as well as September to December; and by ignoring the north-equatorial supply. 2. It arbitrarily determines the question of the Tanganyika, separating it from the Nile-system upon the insufficient strength of a gorilla, and of an oil-palm which is specifically different from that of the Western Coast; and 3. It wilfully misrepresents Dr. Livingstone in the matter of the so-called Victoria Nyanza.