104 HISTORY OP 



all the great mountains in America lie lengthwise, and therefore 

 do not cross their direction. 



But to leave these remote advantages, others assert, that not 

 only the animal but vegetable part of the creation would perish for 

 want of convenient humidity, were it not for their friendly assist- 

 ance. Their summits are, by these, supposed to arrest, as it 

 were, the vapours which float in the regions of the air. Their 

 large inflections and channels are considered as so many basons 

 prepared for the reception of those thick vapours, and impetu- 

 ous rains, which descend into them. The huge caverns beneath 

 are so many magazines or conservatories of water for the. peculiar 

 service of man -. and those orifices by which the water is dis- 

 charged upon the plain, are so situated as to enrich and render 

 them fruitful, instead of returning through subterraneous channels 

 to the sea, after the performance of a tedious and fruitless cir- 

 culation.' 



However this be, certain it is, that almost all our great riveri? 

 find their source among mountains ; and, in general, the more 

 extensive the mountain, the greater the i-iver ; thus the river 

 Amazon, the greatest in the world, has its source among the 

 Andes, which are the highest mountains on the globe ; the river 

 Niger travels a long course of several hundred miles from the 

 Mountains of the Moon, the highest in all Africa ; and the 

 Danube and the Rhine proceed from the Alps, which are pro- 

 bably the highest mountains of Europe. 



It needs scarcely be said, that, with respect to height, there 

 are many sizes of mountains, from the" gently rising upland, to 

 the tall craggy precipice. The appearance is in general different 

 in those of different magnitudes. The first are clothed with 

 verdure to the very tops, and only seem to ascend to improve 

 our prospects, or supply us with a purer air: but the lofty moun- 

 tains of the other class have a very different aspect. At a dis- 

 tance their tops are seen, in wavy ridges, of the very colour of 

 the clouds, and only to be distinguished from them by their 

 figure ; which, as I have said, resembles the billows of the sea.' 

 As we approach, the mountain assumes a deeper colour ; it 

 gathers upon the sky, and seems to hide half the horizon behind 

 it. Its summits also are become more distinct, and appear with 



1 Nature Displayed, vol. iii. p. 88. 

 2 Lettres riiilosophiques sur la Formation, &c. p 1P& 



