The name of the river is three times changed in its course: it is known as the Marañon from its source to the confluence of the Yucayali; from that point to its junction with the Rio Negro, it is called the Solimoes; and from the Rio Negro till it enters the ocean it is the River of the Amazons. The number, length, and volume of its tributaries are in proportion to its magnitude; even the affluents of its affluents are noble streams. More than 20 superb rivers, navigable almost to their sources, pour their waters into it, and streams of less importance are numberless. Two of the largest are the Huallaga and the Yucayali: like their primary, the former has its origin in the mining district of Pasco, and after a long northern course between the Cordilleras it breaks through a gorge similar to that of Manseriche and joins the Marañon in the plains; it is almost a mile broad above its junction. The Spanish governor of Peru sent Pedro de Orsoa down this river in the year 1560 to search for the Lake of Parima and the city of El Dorado. The Yucayali, not inferior to the Marañon itself, is believed by some eminent geographers to be the true Marañon. In a course of 1080 miles it is fed by accessaries from a wide extent of country, and at its junction with the main stream, near the mission of San Joaquin de Omaguas, a line of 50 fathoms does not reach the bottom, and in breadth it is more like a sea than a river. By these streams there is access to Peru, and there is communication between the Amazons and the most distant regions around by other navigable feeders. Nothing is known of the rivers that empty themselves into the Amazon on its southern bank, between the Yucayali and the Madeira; the latter, which is its greatest affluent, comes near the sources of the Paraguay, the principal accessary of the Rio de la Plata. The River of the Amazons is not less extensively connected on the north. The high lands of Colombia are accessible by the Putumayo, the Japura, and other great navigable rivers; the Rio Negro, nearly nine miles broad, a little way above its junction with the Amazons, unites it with the Orinoco by the Cassiquiare; and lastly, the sources of the Rio Branco come very near to those of the Essequibo, an independent river of Demerara.