PHYSICAL GEOGRAPHY, 281 



Andes, in 78 west longitude, is already a large river, on a 

 meridian where all the other streams which can lay a claim to 

 be considered the head-waters of the Amazon have as yet no 

 existence. On going up the Amazon from its mouth, it is that 

 branch on which you can keep longest in the general east and 

 west direction of the river ; and if the actual length of its 

 course is considered, it still keeps its place, for I find that there 

 is not more than ten or twenty miks' difference between it and 

 the Uaycali, reckoning to the most distant source of the latter ; 

 and its course is at present so uncertain, that future surveys 

 may increase or diminish it considerably. 



These considerations, I think, decide the question as to the 

 propriety of considering the Marafion as the true source of the 

 Amazon. We find that from its origin in the Lake Lauricocha, 

 to its mouth in longitude 50 west, in length, following the main 

 curves, but disregarding the minuter windings, is 2,740 English 

 miles. 



Its extent, in a straight line from east to west, is about 2,050 

 miles ; and from north to south, its tributary streams cover a 

 space of 1,720 miles. 



The whole area of its basin, not including that of the 

 Tocantins, which I consider a distinct river, is 2,330,000 

 English square miles, or 1,760,000 nautical square miles. 

 This is more than a third of all South America, and equal to 

 two-thirds of all Europe. All western Europe could be placed 

 in it without touching its boundaries, and it would even con- 

 tain our whole Indian empire. 



The numerous tributary streams of the Amazon, many of 

 them equal to the largest rivers of Europe, differ remarkably 

 in the colour of their waters, the character of the vegetation on 

 their banks, and the animals that inhabit them. They may be 

 divided into three groups, the white-water rivers, the blue- 

 water rivers, and the black-water rivers. 



The main stream of the Amazon itself is a white-water river, 

 this name being applied to those waters which are of a pale 

 yellowish olive-colour. This colour does not seem to depend 

 entirely on free earthy matter, but rather on some colouring 

 material held in solution ; for in lakes and inlets, where the 

 waters are undisturbed and can deposit all their sediment, they 

 still retain the colour. 



The waters of the Amazon continue of the same colour up 



