OROONOKO, or ORINOCO, a celebrated river of South America, and one of the largest in the world. It is 1380 miles in length, including the windings. Its breadth, at 200 leagues from the sea, is about 2500 fathoms, and at St. Thomas, the capital of Spanish Guiana, it is 3850 fathoms. Its depth, at the same place, taken when the waters were at the lowest, was found to be 65 fathoms. The source of this river is not known with certainty, but it is supposed to be in the Ibirinoko mountains, and, according to La Cruz, it rises in the small lake of 1pava, in 55° north latitude, from whence it turns round and enters Lake Pa rima, to the south-east; then, taking a northerly direction, it is joined by several large rivers, from the eastern ridge of the Andes, and here forms the so long disputed junc tion with the great river Amazons. M. Humboldt in 1800 undertook a long and arduous journey, for the purpose of ascertaining this point, and had the satisfaction of placing it beyond a doubt. He entered the Oroonoko by the Cas siquiari, in 30' north latitude, and ascended the cur rent of the great river as far as Esmeralda, the last of the Spanish settlements in that quarter. On its southern, or left bank, it receives the rivers Maquiritari, the Cunucu. numa, Ventuari, Caura, Aruy, and Caroni ; and, from its western bank, it acquires the still larger and more im portant additions of the Cassiquiari, Guariari, the Meta, and the Apure, which last is 500 miles long. The Oroo noko then turns eastward, and dividing itself into a num ber of branches, discharges itself into the ocean by fifty mouths, seven of which only are navigable. The great mouth of the Oroonoko is formed by Cape Barima, to south-south-east, which is in 8° 54' north latitude, and the island of Cangrejos, lying west-north-west of the cape.
They are twenty-five miles distant from each other, but the navigable part of the passage is about three.
The cataracts of the Oroonoko, at the villages Maypura and Atures, in about 6' of north latitude, are described as the most stupendous that are known. The whole scenery of the banks of this river is represented to be of the most magnificent description ; vast forests are filled with aro made trees ; birds of the most beautiful plumage present themselves, and hordes of monkeys follow the steps of the traveller.
The annual inundation of the Oroonoko begins in April, and ends in August ; and, in the northern part, sometimes extends twenty or thirty leagues in a length of 200. This immense extent it retains for the whole month of Sep tember. At the distance of 1300 miles from its mouth, the rise is thirteen fathoms. The waters begin to de crease early in October, and by the end of February it is at its lowest ebb, in which state it continues till the be ginning of April. The Oroonoko abounds in fish and am ?hibious animals of various kinds. The cayman is one of its most formidable inhabitants. Numerous Indian tribes, possessing from 500 to 2000 warriors each, inhabit the banks of this river. The Caribs boast of having 12,000 men, and the Cabarres were still more numerous. To the south of the river, the efforts of the missionaries to civilize them have been entirely fruitless. The mouth of the Oroonoko is in west longitude 50', and north lati tude 8° 30'. See Humboldt's Personal Xarrative.