44 



NORTH-EAST AFEICA. 



cellules, acquires a marshy taste and becomes unwholesome. But all this refuse is 

 swept away or destroyed by the first floods from the Abyssinian rivers, which thus 

 restore to the Nile water its excellent properties. 



The " Gazelle," which joins the main stream in the No basin, is a " bahr," 

 that is, a considerable river, flowing from the west, and during the floods bringing 

 suflicient water to sweep away the temporary obstructions. In its channel are 

 collected a hundred other rivers, whose numbers and copiousness form a striking 

 contrast to the poverty or total absence of running waters characteristic of the 

 Nile basin farther north. Altogether the affluents of the great river are dis- 



Fio;. 13. — The Nile at Khartum. 



tributed very irregularly, thus illustrating, as it were, the discrepancies of the 

 climate. In the region of the plateaux the Victoria Nyanza and Somerset Nile 

 receive feeders both from east and west, for the rainfall is here sufiiciently heavy 

 to cause watercourses to converge from all directions in the great lacustrine 

 reservoir. But north of the Albert Nyanza the affluents occur alternately now on 

 one now on the other bank of the Nile. In the section of its course terminating 

 in the No lagoons it receives contributions only from the west, and farther north 

 only from the Abyssinian highlands lying to the east. Then for a distance of 

 1,500 miles no more permanent tributaries reach its banks either from the right or 

 the left. Even during the rainy season the gorges opening on its valley send 



