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’zighe, 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 Monbuttu; 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[FN#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[FN#23] that his “illustrious friend” would follow the drainage of the country to the western coast.