AM'AZON, MARANON, or ORELLANA, a river which, after traversing nearly the entire breadth of South America, enters the Atlantic between Brazil and Guiana, by a mouth of about 150 m. in width—a mouth though it admits the tide for nearly 500 m., is yet so far from meeting our ordinary notion of an estuary that it repels, or at least overlays, the ocean to a distance of more than 50 leagues. With its various tribu taries—the Napo, the Putumayo, the Yapura, and the Rio Negro from the a., and the Huallaga, the Yavari, the Jutay, the Jurua, the Coary, the Purus, the Madeira, the Tapajos, and the Jingo from the s.—the A. drains 2,330,000 sq.m., an area equal to two thirds of Europe, and is estimated to afford an inland navigation of 50,000 in., a line double the circumference of the globe. In every respect, then, the A. may well claim to be the largest of rivers, excepting only that, in volume of contents as distin guished fronyvolume of discharge, the St. Lawrence, with its computed mass of 11,000 cubic in., has been estimated to be equal to all the other bodies of fresh water on the earth's surface, from the A. downwards. With this exception, which—as the St. Lawrence is really a series of lakes—is rather apparent thari real, the Amazon stands forth as the king of rivers, whether trunk be compared with trunk, or branches with branches, alike in essential features and in the area of basin. Viewed as one grand system, the A., from its sources, from which the Pacific may be seen within a distance of 60 ru., to its embouchure, comprises a course of about 4000 in.; while, gathering its tribute from both sides of the equator along more than 20° of lat., it presents, perhaps, between s. and n , a longer line of natural communication than even between sv. and e. Reckoning from the western range of the Andes, the A. is but little better than a mountain-torrent, till it has burst through the gorges of the eastern range of the chain, where it is overhung by peaks that tower thousands of feet above its bed. But, within 300 m. from the Pacific—a journey of about 20 days for loaded mules—the branch called the Huallaga is practicable for steamers, while, after a run of 325 in., the A. is navigable for vessels drawing 5 ft., growing deeper and deeper and more and more available as it rolls its steadily swelling flood towards the ocean. Nor is this the remotest point of clear navigation from the sea, for the Maranon itself is estimated by Herndon to carry the clear navigation about one fifth higher up, amounting in all to 3360 miles. What an idea do these single threads afford of this matchless net-work of inland navigation! But it is not to its own basin alone, vast as that basin is, that the value of the A. is confined. The Rio Tapajos has its navigation separated only by a portage of 18 in. from that of an affluent of the Plata; the Rio Branco, the main tributary of the Rio Negro, has a water-communication which is only two hours distant from that of the Essequibo; while the Rio Negro itself is doubly connected with the Orinoco, receiving from it the navigable Cassiquiare (q.v.), and wanting only a canal over a portage of six hours to complete a still more useful bond of union, whose superior advantages will certainly one day lead to the necessary improvement. In addi tion to all this, the outlet of this mighty river, besides washing Cayenne, is itself, under nature's guidance, a feeder, as it were, of that highway of nations, the gulf stream.
Thus does the A., to say nothing more of its maritime relations, bring its inland navi gation, mediately or immediately, to bear, Chili alone excepted, on every country in South America—Venezuela, EQiador, New Granada, Bolivia, Peru, Brazil, the Guianas, and the several Argentine republics. This is not mere prospect; not only has the basin proper of the A. been more or less frequently traversed, but also the various joints that knit it to other basins have been tested by experience. The grandest and most singular of them all, besides being explored by Humboldt, has been placed beyond a doubt by the denizens of the country. The barge-builders of San Carlos, at the entrance of the Cassiquiare into the Rio Negro, have long sent vessels, not only down the Rio Negro to Para, on the lower A., but likewise up the Cassiquiare to Angostura, on the lower Orinoco; thus solving, in their own way, the problem which systematic geographers were elsewhere deriding as worse than a fable—as a sheer impossibility. It was not till 1867 that the navigation of the A. was thrown open, but now regular lines of steamers ply between its mouth and Yuriinaguas on the Huallaga. The most important exports sent down the A. are india-rubber, cocoa, cotton, nuts, copaiba, palm-fiber, hides, sarsa parilla, farina, tonka beans, arnotto, and tobacco. Other productions of the countries watered by the A., countries well fitted to become the garden of the world, are coffee, sugar, maize, rice, indigo, grapes, bananas, cabinet-woods, building-timber, game, fish, and precious metals. Steam-boat navigation began on the A. in 1853. In that year, the Amazon navigation company, a Brazilian commercial association fostered by the government, sent its first steamer from Path, the maritime emporium of the A., to Nauta, in Peru; and in 1872, the company had a capital of $2,2.00,000, and nine steamers, five of which ply exclusively in the A. waters; two below Para' and Loreto in Peru, distance 2100 m.; one on the Peruvian branch of the river, 288 in.; one from Para to Obidos, 400 m.; one from Santarem to Faro. The Peruvian government has also a line of steamers on its reach of the A., and up the Huallaga.
The wonderful discoveries made by the late professor Agassiz (1865-66) in the fauna of the waters of the A. have proved what he himself calls 'a true revelation for sci ence.' Their importance will be seen by contrast. The number of species of fish on the whole globe known to Linnaeus about a century ago was 300; in 1840, captain Wilkes collected only 600 species in a voyage round the world with three ships, in an expedi tion lasting four years; but Agassiz saw in five months on the A. alone 1300 species of fish, nearly 1000 of them new, and about 20 new genera. The Plea marina, the largest fish inhabiting fresh waters, and the Acara, which carries its young in its mouth, especially when there Is danger, are denizens of the Aniazon.—Set .13razil and the Bra rams, by Fletcher and Kidder (London and Boston, 1866) ; A Journey in Brazil, by professor and Mrs. Agassiz (London, 1868); A Journey across South America, by Paul Marcos, a translation of which was published by Messrs. Mackie Sons, Glasgow, in 1873.