The largest tributary of the Ucayale, after it takes this name, is the Pachitea, which joins it on the left, in the latitude of 8° 30′, being more handsome in its appearance than considerable, its course not exceeding two hundred miles.
The Maranham, at the confluence where it takes this name, directs its course to the north-east for one hundred miles, receiving, on the left, the Napo, which originates in divers parts of the interior cordillera of the Andes, in the vicinity of Quito, from whence it flows to the south-east, collecting various others, and, after a course of five hundred and fifty miles, discharges itself by different channels, formed by several islands, above which it is twelve hundred yards in width.
With this river the Maranham becomes eighteen hundred yards wide, yet having acquired only a small portion of the volume of water with which it enters the ocean, from whence it is here distant thirteen hundred miles in a direct line. At this part it inclines to the east, and, after fifty miles of course, receives by the right the Cassiquin, which comes from the south, with three hundred and fifty miles of extent.
Seventy miles lower the Hyabary enters, which has its source in the territories of the Torromonas in 11° 30′.
Upwards of one hundred miles further is the mouth of the large Iça, which originates in the skirts of the said cordillera to the north-east of the Napo, and in the vicinity of St. Joam de Pasto, with the name of Putumajo.
The Hyutahy and the Hyurba follow; they are less than the preceding, being about three hundred and sixty fathoms in width, and next to the Teffe, the Coary, and the Purus, which are discharged by many mouths.
On the northern margin it receives the great river Hyapura, after an extensive course from the province of Popayan. This river runs parallel with the Maranham for a considerable distance, discharging itself in that space by nine channels, the mouth of the first being three hundred miles to the west of the last. Auatiparana, Euiratyba, Manhana, Uaranapu, Hyapura, Unana, Copeya, Hyucara, and Cadaya, are the names of the channels, and the order by which the Hyapura enters the Maranham. The Maranham is estimated to be nearly a mile and a half in width, at a certain part, free from islands, about twenty miles below the Purus, where the bottom, it is said, could not be found with a cord of one hundred and three fathoms.
After the Hyapura, its waters are swelled by the entrance, also on the northern side of the Rio Negro, almost equalling it in width and volume; and sixty miles lower, on the right, by the river Madeira, nearly two miles in width, being the most considerable of all the subordinate torrents that fill up the vast space between the receding margins of this wonderful river. The river Madeira was designated Cayary, until the Portuguese gave it the former denomination, in consequence of the large trunks of trees, some of cedar, of an extraordinary size, that floated down at the period of the floods, Madeira being the Portuguese word for wood or timber. It takes this name at the confluence of the Guapore with the Mam ore, which latter has its source in the province of Potoze, traversing that of Santa Cruz, and describing a vast semicircle by the east towards the north, being enlarged by numerous other currents, which join it on both sides to the said confluence, in latitude 10° 22′. One hundred and forty miles above this point, in the parallel of 13°, it communicates with the Benni, by the river Exaltacao, issuing from the lake Rogagualo, from which another of short extent flows to the Mamore.
In front of the angle of the confluence of the Mamore with the Guapore, there is an island of rock, well adapted for the site of a fort, which would command the entrance of both rivers. Upwards of nine hundred miles is computed from this situation to the mouth of the Madeira. In the space of the first two hundred the traveller encounters twelve cataracts, equally astonishing for their grandeur and extent. The attention is first arrested by that which has the same denomination as the river, and not far below the island of rock alluded to. Three of the falls are within the space of a mile and a half. The canoes advancing up the river are unloaded and conveyed in this state, including the different points, for half a mile. The Misericordia next follows, about two miles lower down, and the danger and labour of passing it depends upon the height or diminution of the waters of the river. Proceeding along another interval of the same space, the four cataracts of Reibeirao meet the astonished eye within the distance of four miles. Canoes are here for a considerable way dragged over land.
Twelve miles further is the Figueira, otherwise Araras, formed by small islands and large stones, but of no considerable extent.