Orinoco
2 of the 6 encyclopedias on this shelf carry an entry for Orinoco. Both are reproduced below, so you can see where they agree and where they differ.
Collier's New Encyclopedia (1921)
one of the great rivers of South America, has its origin on the slopes of the Sierra Parima, in the extreme S. E. of Venezuela; its exact sources were only discovered in 1886 by Chaffanjon. It flows at first W. by N., a mountain-stream, as far as lon. 67° W. A little below Esmeralda (lon. 65° 50' W.) it divides and sends off to the S. an arm, the Cassiquiare, which, after a course of 180 miles, enters the Rio Negro, a tributary of the Amazon. The other branch on reaching San Fernando (lon. 68° 10' and lat. 4° 2' N.) is met by the strong current of the Guaviare; the united stream then turns due N., and after passing over the magnificent cataracts of Maypures and Atures and picking up the Meta on the left, meets the Apure. Below the confluence with the Apure the Orinoco turns E. and traverses the llanos of Venezuela, its waters, with an average breadth of 4 miles, being augmented from the right by the Caura 4 and the Caroni. About 120 miles from the Atlantic into which it rolls its milkwhite flood, its delta (8,500 square miles) begins. Of the numerous mouths which reach the ocean over 165 miles of coast line only seven are navigable. The waterway principally used by oceangoing vessels, which penetrate up to Ciudad Bolivar (Angostura), a distance of 245 miles, is the Boca de Navios, varying in width from 3% to 23 miles. The total length of the river is some 1,550 miles, of which 900, up to the cataracts of Atures, are navigable, besides a farther stretch of 500 miles above the cataracts of Maypures; area of drainage basin, 368,600 square miles.
Aiton's Encyclopedia (1910)
the most northerly of the three great rivers of South America . It rises in northern Brazil and flows northward, then eastward through Venezuela into the Pacific. Its mouth lies outward, that is to say, eastward of the Caribbean. In seasons of high water , boats are able to pass from the headwaters of the Amazon into those of the Orinoco by various channels. The river is navigable for a distance of about 900 miles to a point where it is interrupted by rapids. The Orinoco is a mighty stream. Five hundred miles from the ocean it is four miles in width. Its basin is occupied by forests exceeding even those of the Amazon in gloomy magnificence. Trees of enormous size, creeping vines, aromatic odors, bright plumaged birds are beyond description. Hordes of monkeys chatter in the trees. Enormous serpents lie in wait for deer and peccaries. The waters are full of fish and alligators. Beyond the range of forests the basin is occupied by extensive grassy plains. The Orinoco is about 1,500 miles in length. Its basin has an area of 300,000 square miles. See Cassiquiari ; Amazon ; Venezuela
What Has Changed in the Last Century
Collier's noted in 1921 that the river's "exact sources were only discovered in 1886 by Chaffanjon" — but Chaffanjon's claim was disputed, and the true headwaters, at Cerro Delgado Chalbaud in the Sierra Parima, were not fixed until a joint Franco-Venezuelan expedition reached them in 1951. Aiton's 1910 entry contains a plain slip: it has the Orinoco flowing "into the Pacific" before correctly placing its mouth east of the Caribbean, in the Atlantic. The greatest physical change is on the Caroní, the right-bank tributary both accounts name: the Guri Dam, built between 1963 and 1986, created one of the world's largest reservoirs and still supplies much of Venezuela's electricity. The forests and llanos of the basin are now crossed by iron and bauxite mining and by the Orinoco heavy-oil belt, among the largest crude deposits on earth, while Ciudad Guayana was founded near the confluence in 1961.
Written for this edition, 2026.