466 ACROSS AFRICA. [Chap. 



According to the accounts I received, these caves pass right 

 underneath the bed of the river, and are high and lofty. There 

 are several openings on both sides of the river, and stories are 

 told of strangers who had come to attack these troglodytes be- 

 ing hotly engaged at one entrance, and then suddenly finding 

 themselves attacked in rear by a party which had sallied out 

 from another. The inside of these dwellings is described 

 as being of great beauty, with columns and arches of white 

 stone. 



The people here are greatly afflicted with goitre ; and stran- 

 gers residing among them are said to feel symptoms of that 

 disease after drinking the water for a few days. Tliis no doubt 

 points to the existence of a limestone formation. 



Other aflSuents of the Lualaba are the Luama and Lomami 

 — both navigable streams — and the Lowa, described as coming 

 from the north, and it is said to be as large as the Lualaba some 

 distance to the west of Nyangwe. The Uelle of Dr. Schwein- 

 furtli may be an affluent, or pei'haps the head-waters, of this 

 great stream, which must receive the drainage of a very large 

 portion of the continent. 



The Lualaba, if it be the Kongo, of which I think there can 

 be no doubt, must also receive the drainage of all the country 

 north of the Zambesi basin, until that of the Kwanza is reached. 



The volume of the Kongo was roughly estimated by Tuckey 

 at two millions of cubic feet per second ; and even if this esti- 

 mate be too large, there can be no doubt that the mighty river, 

 over a thousand feet deep at its mouth, must receive the drain- 

 age of an enormous area. 



The Kongo also rises very slightly when compared with other 

 tropical rivers, and its rising takes place twice a year. This 

 may be accounted for hj the fact that its basin extends on both 

 sides of the equator, and that, therefore, some of its affluents are 

 in flood when others are low. 



Beyond the ranges of Kilimachio and Nyoka are broad and 

 well-watered plains extending to Kilemba, east of which is a 

 shallow basin about flve or six miles across, where the soil is 

 salt and there are some salt-springs. Several of these basins 

 were said to be near, but this was the only one visited. 



From Kilemba to Lunga Mandi's the country consisted of 



