46 NATURAL HISTORY. 



Chili and Peru. The Cordeliers are exceedingly steep 

 on the west side, but they have a gradual declivity 

 towards the east, and they terminate in vast plains, 

 which are terminated by the largest rivers in the world. 

 This is a consequence of the parallel directions of 

 the different chains of mountains ; and besides the 

 whole continent of Europe and of Asia is broader from 

 east to west, than from north to south ; for there are 

 two modes of conceiving this direction. In the long 

 and narrow continent of South America, there is only 

 one principal chain of mountains, that is, from east to 

 west, or from west to east; in fact, it is in this direction 

 all the rivers of America flow, because, excepting the 

 Cordeliers, there are no very extensive chains of moun- 

 tains, and none whose directions are parallel to them. 

 In the old as well as the new continent, most of tire 

 waters have their greatest extent from west to east, 

 and most of the rivers flow in this direction, which is 

 owing to another cause, to wit, that there are many 

 long chains of mountains parallel to each other, whose 

 direction is from west to east, and because the rivers 

 and other streams are obliged to follow the intervals 

 which divide these chains of mountains, consequently 

 one single chain of mountains, directed from north to 

 south, will produce rivers, whose direction will be the 

 same as that of those which issued from many chains 

 of mountains, whose common direction is from east to 

 west ; and it is for this particular reason, that the ri- 

 vers of America have this direction common with those 

 of Europe, Africa, and Asia. 



A remarkable phenomenon has been observed with 

 respect to rivers, which is, that in the inland parts at 

 a distance from the sea, they flow in a direct line, but 

 in proportion as they approach their mouths they as- 



