306 SIR RODERICK I. MURCHISON'S ADDRESS— AFRICA. [May 23, 1859. 



Kilimanjaro and Kenia, I am of opinion with the learned Cooley * 

 that the elevation and mass of these mountains are not such as 

 would sustain a vast range of snow and ice, the melting of which 

 would account for the annual rise of the Nile. Even if it be 

 assumed that this is really a snowy chain, the exact periodical rise 

 of the Nile could never be caused by a periodical melting of its 

 snows, since the power of the sun under the Equator is so nearly 

 equable throughout the year, that it must operate in filling the 

 streams which descend from the mountains with pretty much the 

 same amount of water at all seasons. The great phenomenon of the 

 periodic rise of the Nile is, it seems to me, much more satisfactorily 

 explained by the annual overflow of a vast interior watery plateau, 

 which, is, thanks to Captain Speke, ascertained to have an altitude 

 much more than adequate to carry the stream down to Khartum, 

 where the Nile is believed to flow at a height of less than 1500 feet 

 above the sea ; and as the river below that point passes through an 

 arid country, and is fed by no lateral streams, it is to. the southern, 

 central, and well- watered regions that we must look for the periodic 

 supply. 



On consulting Captain Speke respecting the rainy season of that 

 part of the interior of Africa which lies between Ujiji and Unyan- 

 yembe, I find that in about east longitude 30° and south latitude 5° 

 the rains commence on the 15th November and end on the 15th 

 May, during which period of six months they fall in an almost 

 continuous downpour. Farther northward, where the Lake Nyanza 

 lies, the rainy season, in the common order of events, would com- 

 mence, he supposes,' somewhat later, and probably at a time which 

 will account for the periodical rise of the Nile at Cairo on the 18th 

 June. In support of this view, Captain Speke states that the river 

 Malagarazi, which drains the surplus waters from the south-east 

 slope of the mountains between the Lakes Nyanza and Tanganyika, 

 when first crossed by the expedition, was within its banks, but on 

 the 5th June it had quite overflowed them and constituted a stream 

 100 yards broad, running westwards into the depressed lake of 

 Tanganyika. Now, as according to the Arabs, and other intelligent 



* This acute scholar has shown his power as a comparative geographer by a close 

 analysis of the qucestio vexata respecting the !Nile of the ancients, and shows that the true 

 Nile of Ptolemy was the Blue Nile, which descends from the mountains of Abyssinia. He 

 also shows that the great lakes of the Nile of Ptolemy are at the Equator — a view now 

 confirmed by the researches of Speke. As to Kilimanjaro, he says it is " an insulated 

 mountain in a sea-like plain, and on a fifth scale of the magnitude required for maintaining 

 perpetual snow near the Equator." See also his work * Inner Africa Laid Open,' in which 

 he explains the existence of a gieat sea or lake in the interior of Eastern Africa. 



