Latterly, when speaking of the Lualaba, Livingstone writes to Sir Henry Rawlinson:—"The drainage clearly did not go into Tanganyika, and that lake, though it probably has an outlet, lost all its interest to me as a source of the river of Egypt."
We are, therefore completely in the dark concerning the flow of water from the Lualaba south of the equator, and of Schweinfurth's Welle north of the equator, but both these large rivers were tending to the same direction, north-west. The discovery of these two rivers in about the same meridian is a satisfactory proof of the western watershed, which completely excludes them from the Nile Basin. If the Tanganyika lake has no communication with the Albert N'yanza, the old Nile is the simple offspring of the two parents—the Victoria and the Albert lakes. (This is now proved to be the case.)
When the steamer that I left at Gondokoro in sections shall be launched upon the Albert N'yanza, this interesting question will be quickly solved.
Early in November, 1871, when I was on the Nile south of Regiaf, I noticed the peculiar change that suddenly took place in the river. We were then in N. lat. 4 degrees 38", below the last cataracts, where the water was perfectly clear and free from vegetation, with a stream of about three and a half or four miles per hour.
Suddenly the river became discoloured by an immense quantity of the
Pistia Stratiotes, of which not one plant was entire.
This aquatic plant invariably grows in either dead water or in the most sluggish stream, and none existed in the part of the river at N. lat. 4 degrees 38".
I examined many of the broken plants, which, instead of floating as usual on the surface, were mingled in enormous quantities with the rushing waters. None were rotten, but they had evidently been carried down the numerous rocky waterfalls which occupy the interval between N. lat. 3 degrees 34" and 4 degrees 38", and were thus bruised and torn asunder.
The extraordinary influx of damaged aquatic plants continued for many days, and unmistakably denoted the rise in the level of the Albert N'yanza at that season (say 1st Nov.). Above the falls, in N. lat. 3 degrees 32", there is very little current in the broad deep Nile; and in about N. lat. 3 degrees this river is several miles in width, with no perceptible stream. In those propitious calms the Pistia Stratiotes grows in vast masses along the shores, and the annual rise of the lake creates a current which carries the plants towards the cataracts, and consequent destruction.
By this sign I conclude that the maximum of the Albert N'yanza would be during the month of November.