ORINOCO, or Oronoko, a river of Colombia, in South America. Like all great rivers, its upper waters separate into several branches, and it does not appear that the main source has been ascertained with any degree of certainty. According to La Cruz d’Olmedilla, it issues from a small lake called Ypava, situated in north latitude 5° 5', whence, by a bend of a spiral form, it enters the lake Parima; but although the existence of this sheet of water has been determined, doubts are entertained whether it may not owe its origin only to the temporary overflowings of the river. From this lake it is said to issue by two mouths; and after a very circuitous course of upwards of fifteen hundred miles, including its windings, it flows into the Atlantic Ocean, opposite to the island of Trinidad, by about fifty mouths, seven of which are navigable. The Grande Boca, or principal mouth, which is six leagues wide, is south-east of Trinidad, in latitude 8° 30'north, and longitude 59° 50' west. A soft mud bank, formed by the debris brought down by the river, and of course just an extension of the delta of the Orinoco, which will one day be clothed with vegetation, stretches a considerable way into the ocean on the left of the grand mouth, forming one line of the channel to the entrance of the river. The other side of this channel consists of hard ground, covered with shells and shingles, and on which the water deepens and shoals continually. At its estuary it presents the appearance of a boundless lake, and for a great extent its fresh waters penetrate into the bosom of the ocean, almost uncontaminated by saline matter. “Its green-coloured stream,” says Humboldt, “and its waves dashing over rocks in milk-white foam, are strongly contrasted with the deep blue of the sea, which is separated from them by a strongly marked line.” Such is the force of the stream formed by the Orinoco between the main land and the island of Trinidad, that vessels overcome it with great difficulty, even when favoured by a fresh breeze from the west. This solitary and dreadful place, perpetually tormented as if by a whirlpool, is called the Melancholy Gulf, the entrance to which is formed by the Dragon’s Mouth. There, in the midst of furious waves, says the great traveller just quoted, enormous rocks raise their isolated heads, the remains of that ancient dike which formerly joined the island of Trinidad to the coast of Paria. It was the aspect of these places which first convinced Columbus of the existence of the continent of America. The unrivalled navigator reasoned admirably when he concluded that such an immense body of water must have accumulated during a very lengthened course, and that the country through which it flowed must be a continent, and not an island. He, however, supposed it to be a continuation of the coast of Asia; and, from the ethereal clearness of the sky, the refreshing mildness of the evening air, and the aromatic odours which came wafted by breezes from the land, the Orinoco appeared to him to be one of the four streams which issued from the terrestrial paradise to fructify and divide the earth, and he believed that he was about to set foot in the garden of Eden.

Within the bar of the Orinoco the water gradually deepens, the force of the current continuing very considerable, and sometimes during the rainy season running at the rate of six miles an hour, so that navigation upwards is exceedingly difficult, except by steam-boats. At some distance within the Grande Boca of the river there is an island very thickly wooded, and forming the segment of a large circle. Indeed the magnificence of the scenery on the banks of the Orinoco is the astonishment of every traveller. Forests of boundless extent expand on either side, and, being filled with aromatic herbsand flowers that diffuse the most delightful odours, and all alive with birds of beautiful and glancing plumage, from the lovely mocking-bird to the grand vulture and fiery-red flamingo, together with hordes of monkeys, which disport from bough to bough, exhibit a richness, grandeur, and variety of scene which defies description. Passing these forests, enormous plains stretch out like oceans of verdure, far beyond the horizon embraced by the eye; and the sublimity of the scenery on the Orinoco is enhanced by several cataracts, of which Humboldt has distinguished and described those of Maypuresand Atures. Their elevation is inconsiderable, and both owe their existence to an archipelago of little islands and rocks. The appearance of these rapids, however, is exceedingly picturesque and beautiful. “When the traveller descends from the village of Maypures to the brink of the river, after clearing the rock of Manimi, he enjoys a truly astonishing prospect. At once a sheet of foam stretches out before him, to fully a mile in extent. Masses of rock, of an iron-black colour, rear their rugged fronts, like towers, out of this misty cloud. Every island, every rock, is ornamented with luxuriant trees, closely grouped together. A thick smoke constantly hangs suspended over the water; and through this foggy vapour, which rises from the foam, shoot up the tops of lofty palm-trees. As soon as the burning rays of the setting sun mingle with this humid cloud, the optical phenomena which are produced actually give an air of enchantment to the scene. The coloured arches successively appear and disappear, and their image incessantly hovers before the eye at the mercy of the wind. During the long season of the rains, the murmuring waters have accumulated little islands of vegetable earth round the naked rocks. Adorned with the drosera, the mimosa with its foliage of silver white, and a multitude of other plants, these form beds of flowers in the midst of frowning rocks.” [7:16:537] The Orinoco is navigable, without difficulty, for two hundred and sixty leagues, to the rapids of Atures, where its mean height above the sea is, according to the traveller just quoted, not more than three hundred and fifty feet, and thence, after two short portages, for one hundred leagues more, to the point near Esmeraldo, where the celebrated bifurcation of this river takes place, and a portion of its waters descends along the natural Canal of Casiquiari, to join the Rio Negro and the Amazon. The communications which exist between the Orinoco and the Amazon constitute one of the most astonishing phenomena of physical geography. More than half a century has elapsed since the fact was made known by the Portuguese; but for a long period after this it was pertinaciously maintained by systematical geographers, that such conjunctions of rivers were impossible. By the enterprise and perseverance of recent travellers, however, it has been proved that this is no anomaly; and we no longer stand in need of either analogies or critical reasoning to support the fact. Μ. de Humboldt has navigated both these rivers, and examined and described this singular arrangement of the land. It is now put beyond a doubt, that the Orinoco and the Rio Negro flow along a plateau, which at this part has no actual acclivity. A valley then intervenes, their waters flow into it, and there unite, thus forming the celebrated Casiquiari, by means of which MM. Humboldt and Bonpland passed from the Rio Negro into the Orinoco. It is believed that there are also other communications between the Rio Negro and the different tributaries of the Amazon. On both sides along its course the Orinoco receives many tributary streams, of which three in particular, the Apure, the Meta, and the Guaviare, flowing from the westward, have also long navigable courses. The Apure falls into the Orinoco about four hundred and forty miles from the mouth of the latter river, in latitude 7. 36. 23. north, and longitude 69. 7. 29. west. The course of the Apure is as serpentine as that of the Orinoco, only on a much smaller scale, the tributary being in no part of its course much more than a musket-shot across. At rather more than one hundred miles from the confluence of the two rivers is San Fernando de Apure, a considerable town in the province of Apure, and a place of some commerce. From thence the navigation is continued, partly on the Apure and partly on the river Santo Domingo, to Toruno and Varinas, at a distance of above two hundred miles farther. The line of navigation of this branch of the commerce of the Orinoco extends, therefore, nearly eight hundred miles from the mouths of the river to the extremity of the province of Varinas. About sixty miles below the cataracts, the Orinoco receives the Meta, a river which, issuing from the paramos of Cundinamarca, keeps its course parallel to them for a hundred and fifty miles, receiving in its progress their tributary streams; and then bending to the east, crosses the llanos of Casanare, and completes a course of more than four hundred miles before its confluence with the great river.

At some future period the navigation of the Meta will become an object of very great importance to Guiana, and; all the other eastern departments of the republic. The Guaviare is also a very considerable navigable river, formed by a number of streams which flow down the eastern declivities of the Andes. It joins the Orinoco at San Fernando de Atabapo, in latitude 4° 3' north, and longitude 68° 10' west, which is the point where the Orinoco takes a great bend to the north. When steam navigation shall have become common in this quarter of the world, the river Guaviare will prove of immense advantage to some of the interior provinces of Colombia, as a medium through which their produce may be conveyed to the sea-ports of the republic. There are a great number of other streams, tributary to the Orinoco, no less than three hundred being enumerated. Many of the upper streams of this river display the singular phenomenon which has been called “black waters.” Under the shadow of the palm-trees their colour becomes of a deep black, but, in transparent vessels, it assumes a yellow hue. The absence of crocodiles and fish (which are very plentiful farther down), a greater degree of coolness, a smaller number of musquitoes, and a more salubrious atmosphere, distinguish the region of the black waters. Humboldt surmises that they derive their colour from a solution of carburet of hydrogen, resulting from the decomposition of the multitudes of plants that cover the soil through which they flow. With regard to the breadth, depth, and quantity of water discharged by the Orinoco, as well as the size of the delta which it has formed, our information is by no means precise. At six hundred miles from the ocean it is said to be from five to six hundred yards across, and at Angostura or St Thomas’s, situated two hundred and forty miles from its mouth, to be nearly eight hundred yards across. Its depth appears to be very great; even when the waters are at the lowest, it is no less than sixty-five fathoms in some parts; and during the rainy season it inundates the immense plains through which it flows, extending during the highest floods from eighty to ninety miles on either side, and thus presenting to the eye the appearance ofavast inland sea, rather than ariver. These facts, together with that of the vast extent to which the current of the river may be traced in the ocean, are sufficient to prove that the quantity of water brought down by the Orinoco is inferior to that of few rivers on the face of the globe. The annual swell of the Orinoco commences in April and ends in August. At the distance of thirteen hundred miles from the ocean the rise is about thirteen fathoms. In the beginning of October the water begins to fall, and, quitting the deluged plains, continues to diminish till March, when it is at the lowest ebb. This river abounds in fish of various descriptions. Amphibious animals are also found in great numbers on its shores; the cayman or alligator frequents its waters, and is very formidable. From one of the best maps of Colombia which have been published, it appears that its delta extends above one hundred and fifty miles in length at the base, and that from the middle of this line to the apex of the triangle it is above one hundred miles in depth. (r. b. r.)