Introduction xxiii 



Central Africa. During the trip, which lasted for 

 nine days, the explorer made astronomical observa- 

 tions which will have the effect of modifying the 

 map of the great lake. 



The explorer left Lake Nyassa to ascend the high 

 plateau which separates the lake from Lake Tanganyika 

 at Karonga. The exploration of unknown regions and 

 the deciding of some important geographical questions 

 took up several months at this period of the journey. 

 The explorer entered upon an entirely new route in 

 the Ubemba country, and mapped hydrographically 

 the Chozi and Chambezi. It has been thought that 

 some of the sources of the Congo were in the neigh- 

 bourhood of these two rivers ; but I believe that 

 M. Foa is the first to show that this really is so 

 by mapping the network of small streams which 

 flow into the Chozi and Chambezi in the Ubemba 

 country. 



Tanganyika was then explored in a similar 

 manner. Embarking at Urungu, M. Foa devoted 

 three weeks or more to visiting its shores in an 

 arab dhow. He drew up a detailed map of the 

 lake in five parts, and studied the question of its 

 origin. The shells which he brought back with him 

 for the Paris Museum support the theory of the 

 naturalist Gunther that it is a former arm of the sea 

 isolated by the rising of surrounding land i.e., it 

 is a " relicten-see." On Tanganyika and in the 

 immediate neighbourhood he saw the good work which 



