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 miles' 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 Maranon 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 n orth to south, itsjributary streams cover a space-of- 1 -fi -20- 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
