241 
come from the mountains of Kong, to the north-east 
and east; the Misselad, the Kulla. and many other in- 
termediate ones to the north-west; the Kuku, the Ga- 
•zel, and others, to the south and south-west; in a word, 
all those of the interior part of Africa which are known 
to us, have their direction towards the centre of this 
continent. 
The relation of some travellers in the interior part of 
Africa, as well as the informations procured from the 
inhabitants, agree in asserting, that during several 
months the continual rain in this country is so consider- 
able, that the animals as well as the plants are affected 
by it, and brought to a state of extreme debility. 
Having no positive metrical observations on the quan- 
tities of the water in these parts, we must have recourse 
to approximating calculations, founded on comparisons 
with other known places. It is known, that in Europe 
the rain water which annually falls is upon an average 
to the depth of 18 inches. This quantity increases to- 
wards the south. At Algiers from 27 to 28 inches of 
rain water falls annually; the year 1730 is known to 
have produced 30 inches, and the year 1732 even 44 
inches. At Madeira 31 inches of water fell a-vear; 
and, according to the observations of Baron Humbolt, 
the annual rain under the tropics amounted to .70 in- 
ches. The above-mentioned vast surface is cut in its 
middle by the tropic; but as I mean not to avail my- 
self of every supposition, I will only fix at 54 inches 
the height of the rain water, which is 16 inches less 
than Mr. Humbolt's observations would give me a 
right to establish for my basis. I will not take into 
consideration the rains of the Desert, but shall suppose 
vol. i. h h 
