CHAPTER XXIV. 



Lieutenant Cameron 's Expedition to Lake Tanganyika — Discovery of the Lukuga, 

 the long-looked for Outlet to the waters of the Lake — Lieutenant Grandy's Expe- 

 dition to the Congo District — Recall on the Death of Livingstone. 



ONE of the most interesting problems -which remained to be solved in con- 

 nection with African geography was the system to which Lake Tanganyika 

 belongs. Siuce the discovery of this lake by Burton and Speke on the 13th 

 February, 1858, the solution of this question has exercised the ingenuity of 

 geographers, and has given rise to various conflicting theories. Captain Burton 

 describes the lake as occupying a position on the western extremity of the 

 eastern third of the breadth of Africa, and as lying parallel to the Inner 

 African line of volcanic action. The general formation suggested to him the 

 idea of a volcano of depression, not of a reservoir formed by the drainage of 

 mountains. Judging from the eye, the walls of this Tanganyika basin rise 

 in an almost continuous curtain to two thousand or three thousand feet, and 

 its length is over three hundred miles, with a mean breadth of twenty miles. 

 Burton found the water of the Tanganyika to be deliciously sweet ; yet 

 a careful investigation and comparison of statements, led him to the belief 

 that the lake receives and absorbs the whole river system of that portion 

 of the Central African depression whose watershed converges towards the 

 great reservoir. Burton ascertained that the Rusizi flowed into the lake 

 at the northern, and the Marungu at the southern extremity, while on the 

 eastern side he had himself descended the incline for two hundred and forty 

 miles, until he came to the shores of the lake, and had seen that the 

 Malagarazi and other rivers flowed into it. He, therefore, conjectured 

 that Tanganyika had no outlet, suggesting that it maintains its level by an 

 exact balance of supply and evaporation, and that the freshness of its waters 

 is accounted for by the saline particles deposited in them being wanting in 

 some constituent which renders the salt evident to the taste. But the uncer- 

 tainty gave rise to endless discussion, and the solution of the question was 

 certainly one of the most important achievements which remained for future 

 African explorers. Some geographers maintained that the Rusizi flowed out 

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