ORINOCO, a lerge river of South America, which has its origin, according to the most recent information, not in the centre, but on the southern declivity of the eastern part of the mountain system called l'arime. These mountains spread over a groat part of the eastern portion of the republic of Venezuela, end the north-east districts of the empire of Brazil. In length they extend nearly 1200 miles, between 51' and 63' 30' IV. long. Their width varier) between 140 and 450 miles, between the parallels of 1° and 3' N. let. According to a rough calculation, this mountain system covers a surface of about 400,000 square miles. The mountains are separated from the floras of the Atlantic by a low and flat country varying in width between 30 and 70 miles. The southern portion, as far as is known, is a mass of rook, of which the general level has an elevation of from 1500 to 2000 feet above the sea. Few of the hill. and ridges rise more than soma hundred feat, and • very few summits attain more than 1000 feet above their base. The country along the water-courses is thickly wooded, as well as the greater part of the country between them ; but many of the level tracts are savannahs without trees, or only covered with low bushes, which however display • great luxuriance of vegetation. West of 53' W. long., and near 4' N. lat., a continuous range begins, which runs westward to 04' W. long. nearly under the same parallel, and west of 61' W. long. inclines more to the south, so that at its termination near 66' IV. long. it reaches nearly to 3° N. isle This range is called Sierra l'acaraim*. In its eastern part it rises from 1500 to 2000 feet above its base, and from 3000 to 4000 feet above the sea-level. Farther west it rises several thousand feet above the sea, and terminate. with the Cerro Alaraguaca and the Cerro Duida, whose summits attain an elevation of about 10,000 feet, Along the southern base of the Sierra Pemmican the hie Barium runs eastward ?nd the Rio Tokoto westward, and by their junction ems 60' W. long. the Rio llranco, an affluent of the Amazonas, is formed.
The source of the Orinoco hue never been visited by Europeans, nor has any information respecting it been obtained from the natives, who are an aboriginal rase known as the °micas, and who have hitherto prevented all awes' to foreigners. it is supposed that this river rises
near 04' IV. long., nod between r and 4'N. lat. Il umboldt advanced up the stream as far as the mission of Esmeralda; and he says that some monks had penetrated several miles farther to the confluence of the river Chigulre, where the Orinoco is so narrow that the native. have made a bridge over it of creepers at the foot of a cataract. Behamburgk confirms this account.
At. this point the river runs in a general western direction, and several miles farther down it divides into two arms, of which that which flows to the south-west is called Caseiquiari, and after a rapid course of nearly 100 miles joins the Guainia, or ltio Negro, thus forming a natural water-communication between the Orinoco and the Amazonas, Into which latter river the OtlaiDiA falls. [Blum.] The Orinoco continues a wide river, running in a western direction along the southern base of the Perim. Mountains until it approaches 63' IV. long., when it is joined by the Atabapo from the south and by the Guaviare from the west. From the confluence of the last-mentioned river its course lies to the north, along the western base of the Parimo Mountain; and in this part its navigability is interrupted by the Raudales of Maypures and Atures, between 5° and 6° 40' N. lat. The Raudalea are a peculiar kind of cataract. The bed of the Oriuoco at Maypures and Atures, which is nearly 8500 feet wide, is divided into numerous narrow channels by rocks and rocky islands; between which the water runs with great rapidity, and forms a succession of small cascades. The highest of these cascades does not exceed 9 feet, and the river descends at Maypures in about 6 miles only about 30 feet. But the velocity with which the confined body of water runs in the narrow channels renders it impossible to ascend the raudale. The ltaudale of Atures is only half a mile long, and of a similar description. Below these modeles the river continues to flow between low but rocky banks. Opposite the mouth of the river Meta, which joins it from the west, is a powerful whirlpool round an isolated rock, called the Stone of Patience, from the circumstance of its generally taking two days to pass it at low water.