a large river of Venezuela, South America. Its source has never yet been visited by European travellers; for although both Baron Humboldt in 1800, and Schomburgk in 1838, penetrated very near the place where it takes its rise, yet both these travellers were prevented from reaching it by the treacherous outrages of the Kirishana savages who inhabit the district adjacent to the source. The latter of these travellers, however, reduced the limits within which the actual head is to be found to a space of 30 miles. The reports of the Indian tribes on the banks of the river agree in placing the source of the Orinoco in the Parima Mountains, on the borders of Brazil and Venezuela, not far from that of the Parima, which flows in an opposite direction, between 3° and 4° N. Lat., and about 64° W. Long. It flows at first W.N.W., and receives from the N. the Paramu, a river remarkable for the number and height of its falls. Below its confluence with this river the Orinoco is broad, but shallow, and much interrupted by sand-banks. It flows sluggishly through a low, flat region, broken only by a few scattered hills densely wooded. About 13 miles below the village of Esmeralda, the most remote Christian settlement on the river, the Orinoco divides itself into two branches; one of which, taking the name of the Cassiquiare, or Cassiari, flows S.W., and, after a course of 120 miles, joins the Rio Negro near San Carlos; while the other branch, retaining the name of Orinoco, continues to pursue a N.W. direction. The former of these thus forms a sort of natural canal, joining the waters of the Orinoco with those of the Amazon, of which river the Rio Negro is an affluent; and, as the waters of the Amazon are only separated from those of the Paraguay in the south by a portage of three miles, there is, with this exception, a continuous communication by navigable rivers from Buenos Ayres in S. Lat. 35. to the mouths of the Orinoco in N. Lat. 9. Below its bifurcation the Orinoco skirts the base of the Parima Mountains, and receives the Venturi from the right, and still further down the Guaviare from the left. After its confluence with these rivers, in W. Long. 68., it changes its direction, and flows for some distance due north, skirting the western foot of the Parima Mountains. In this part of its course the navigation is interrupted by the rapids, or Raudales, as they are called, of Maypures and Atures, the former 80, and the latter 116 miles below the confluence of the Guaviare with the Orinoco. The river is here more than 8000 feet broad, but is so broken up by an immense number of small islands and rocks, as to leave, in many places, a channel no broader than 20 feet. Between these islands there are numerous cascades, not exceeding 9 feet in height; but, as the great body of water flows through these narrow openings with great force and rapidity, any attempt to ascend the rapids in boats must inevitably be followed by the destruction of the boat and great danger to the lives of the daring navigators. Below this point the navigation is not again interrupted; but at the confluence of the Meta, a tributary which joins the Orinoco from the W., there is a whirlpool which occasions considerable delay to the voyager. From its bifurcation to the confluence of the Meta, the Orinoco forms the boundary between Venezuela on the E., and New Granada on the W. To the north of this point the river takes a curve towards the N.E., and, after receiving the Apure from the left, it flows nearly due E. to the Atlantic. About 130 miles from the sea it forms a delta, by sending to the N. a branch which divides itself into several streams, called the Bocas Chicas, or small mouths, and falling partly into the Gulf of Paria and partly into the Atlantic. These, though many of them are navigable and of considerable size, are much less than the main stream, which is called the Boca de Navios, and is divided, for the distance of about 40 miles, by a line of islands in the middle, into two channels, each about two miles wide. At the great mouth of the river the breadth is upwards of 60 miles, and there extends across the navigable channel in the centre a sand-bar with 17 feet of water. The length of the Orinoco is estimated at 1600 miles, for about half of which distance it is navigable. It receives more than 400 navigable tributaries, the largest of which have been already noticed. At a distance of 560 miles from the sea this great river exceeds 3 miles in breadth. The tide reaches as far as Bolivar, more than 250 miles from its mouth; and at this place the breadth is 4 miles, and the depth 65 fathoms.

The area of the country watered by the Orinoco and its tributaries is estimated at 200,000 square miles. This region is entirely occupied by the llanos, or levels of Venezuela—immense flat plains, stretching from the coast chain to the Parima Mountains, and from the Atlantic to the Andes, rising in some parts of the coast to the height of 1300 feet; but in many places hardly at all above the level of the sea. The greater part of these plains is entirely destitute of trees; but the region on both sides of the Guaviare, and thence northwards along the left bank of the Orinoco to the Meta, is covered with dense forests. In the dry season the open plains present an arid and barren appearance, but when the rain falls they are suddenly covered with luxuriant vegetation; the rivers overflow, cover the plains with vast sheets of water, and sometimes extend even into the forests. The rising of the Orinoco begins in the end of March, proceeds slowly at first till it attains its greatest height in July and August, and then, more slowly than it rose, decreases. Its greatest height on an average at Bolivar is 24 or 25 feet, but in the upper part of its course it attains a height of about 30 feet, and in one contracted channel it is said to rise 120 feet above its ordinary level.