39 



in length, are pretty near it's source, in the first 

 sixth of it's total length ; and five sixths of it's course 

 are entirely free. We find the great falls of the 

 Oroonoko on a point far more unfavourable to 

 navigation ; if not at the half, at least much be- 

 yond t he first third of it's length. In both rivers 

 it is neither the mountains, nor the different 

 stages of flat lands lying over one another, 

 whence they take their origin, that cause the 

 cataracts ; they are produced by other moun- 

 tains, other stages [biefs], which, after a long 

 and tranquil course, the rivers have to pass 

 over, precipitating themselves from step to step. 



The Amazon does not pierce it's way through 

 the principal chain of the Andes, as was affirmed 

 at a period when it was gratuitously supposed, 

 that, wherever mountains are divided into 

 parallel chains, the intermedial or central ridge 

 must be more elevated than the others. This 

 great river rises (and it is a point of some im- 

 portance to geology) to the east of the western 

 chain ; which alone in this latitude merits the 

 denomination of the high chain of the Andes. 

 It is formed by the junction of the river Agua- 

 miros with the Rio Chavinillo, which issues 

 from the lake Llauricocha, in a longitudinal 

 valley bounded by the western and the inter- 

 by the mid stream would traverse) are calculated according 

 to methods altogether different. 



