The rivers of Buenos Ayres are innumerable, but the largest and the most noted is the Rio de la Plata, which may be termed the great channel by which the south-eastern part of America is drained. This noble stream is the conjunct flood of the Paraguay, the Pilcomayo, the Parana, the Uruguay, and a multitude of minor rivers which rise either in the Andes or the mountains of Brazil.
It was first discovered by Juan de Salis in 1515, who sailed up as far as an island in 34° 40' south latitude. The distance from the confluence of the Parana and Paraguay to the mouth of the La Plata is 600 miles; but if the length of any of the three great streams is added, the La Plata will not yield in magnitude of course to the Amazons or to the Orinoco.
The Paraguay is generally supposed to be the original river; this stream rises in 13° south latitude in the mountains, forty leagues north of the Portuguese town of Cuyaba, and on the opposite side of the chain in which rises the Arinos, a broad navigable river flowing into the Maranon. The sources of the Paraguay are very numerous, forming, soon after their issue, large rivers, and successively joining into one stream, under the name of the Paraguay. In 16° 24' south latitude, seven leagues from Villa Bella, the Jauru flows into this river, and is noted as being the point where a fine marble pyramid is erected, which was brought from Lisbon, and denotes, by several inscriptions, that this place is the boundary of Brazil and Spanish America. From its sources to this point the Paraguay has a navigation interrupted only by one fall; and the lofty chain of mountains in which this river rises, are terminated seven leagues below the pyramid, in south latitude 16° 43' by a point called Morro Excalvado. East of this cape all is marsh; nine leagues further south, the Rio Nuevo joins the Paraguay; this river was only discovered in 1786. In 17° 33' the west or Spanish banks of the great river again become mountainous, and three leagues to the south of his parallel there is a deep break in the chain which forms the mouth of lake Gaiba, which is connected with another named Uberava; six leagues and a half below the mouth of the Gaiba, and opposite the mountain bank the St. Lourenço or Porrudos enters the Paraguay from Brazil. This river receives several very large ones, such as the Cuyaba, the Paraiba, the Jaquari, and the Itaquiri. The Itaquiri rises near the great Parana in Brazil, and allowing only for a short portage, canoes actually circumnavigate the country included between the Parana and the Paraguay.
The mountains continue on the western banks under different names; on the eastern bank the river receives the Taquari by many estuaries, the largest of which is in 19° 15' south latitude, and 54 degrees west longitude. Five leagues lower, and on the same side, the Embotetieu or Mondego, flows into the Paraguay, one league below the mouth of which two high capes front each other, and here, at the foot of the mountain, on the west, is Fort Nueva Coimbra, the last and southernmost Portuguese settlement on the Paraguay, which, after bounding the possessions of the two nations from the pyramid of Jaura, becomes wholly a Spanish river, after passing Bahia Negra, a large inlet eleven leagues south of Coimbra.
Thence the river continues to south latitude 21°, where, on the west bank, on a hill named Miguel Josef, the Spaniards have a station with four pieces of cannon, named Fort Bourbon, and previous to reaching this fort, the little river Guirino flows into it from the east. In south latitude 21° 22' the river forms two channels by passing an island, and the banks are here high on both sides, the interior being very mountainous. At this point the great inundations of the river which commenced at the mouth of the Jaura, and have received the name of Lake Los Xarayes terminate.
During the rainy season, the channel of the Paraguay is here confounded with those of its tributary streams, in such a manner that it is difficult to find. The banks of the river continue high; and in 22° 5' south latitude, it receives a large river from the west, and twenty leagues south of this, the Corientes joins its streams.
The Xexuy flows into it from the east in 24° 11'; from thence the Paraguay runs southwards for thirty-two leagues to the city of Asuncion, the capital of Paraguay.
Six leagues below Asuncion, the first mouth of the great Pilcomayo joins the main river, its second mouth being fourteen or sixteen leagues lower. In the intermediate space on the eastern side several small rivers join, and on one of them, the Tibiquari, at 20 leagues south-east of Asuncion is Villa Rica, a fine Spanish town. The Rio Vermelho enters the west bank of the Paraguay in 26° 50' on which, in the interior, is the town of Salto. The stream of the Paraguay, being now augmented by the Pilcomayo, proceeds with increased rapidity and volume to 27° 25', where the immense body of waters, (much larger than itself) of the Parana join it, and their united streams take the name of the Rio de la Plata, and continue their course by an immense channel to the south, forming several islands, and receiving many noble streams, till it has passed the thirty-fourth degree of south latitude, when it begins to take an easterly course, and after receiving the great Uruguay or River of the Missions above Buenos Ayres, it flows with a steady and majestic course, and by an immense estuary into the Atlantic ocean. The cape Santa Maria on the north, and St. Antonio on the south side of its mouth are 180 miles distant from each other, in 35° 30' south latitude; but the navigation of this fine river is interrupted by banks, rocks and islands, and is rendered dangerous by violent winds, which, sweeping with great velocity over the plains, cause perfect hurricanes in the La Plata. It is even said that the storms are more frequent than at sea, and it requires very little nautical knowledge to know that they must be infinitely more dangerous than on that element. The water of the ocean is fresh at a great distance from the La Plata, owing to the rapidity with which that river discharges itself.
The other noted streams and features of Buenos Ayres will be noticed in the description of the different provinces.