In this government the mountainous parts are chiefly those situated to the north-west of the river Uruguay, and which border on the Portuguese frontiers; they are little known, and are inhabited only by tribes of savage and warlike Indians, who set the missionaries at defiance.
The rivers of Buenos Ayres are the great La Plata already described, the Parana, the Uruguay, and many others of less note, but generally very large.
The Parana rises in the province of Minas Geraes to the south of the city of Joas del Rey, in Brazil, in some lofty mountains, and runs from north-east to west for 300 leagues, when it joins the Paraguay, receiving in its course innumerable streams; at the distance of 125 leagues from its mouth it has two falls of a tremendous nature, which render it necessary for the boats that navigate it to be carried a short distance over-land. The Parana is a considerable river before it enters the Spanish territories, and after passing the frontiers of Brazil in about 24° 40' it flows in a south-west course through the colonies of the Jesuits, in a country of incomparable fertility and of a delightful aspect. It seldom overflows its banks, owing to the breadth and depth of its channel, and it is much more rapid than the Paraguay as it flows from higher ground: at its junction with the Paraguay it is nearly two miles broad, and incloses innumerable islands, which are overflowed in the annual inundations; but it is not navigable in its whole extent, on account of the two falls and several rapids.
This river was always supposed (and is still conjectured by some geographers) to be the main stream of the great La Plata.
The third great river of Buenos Ayres is the Uruguay, which rises about the 28° of south latitude, in the Portuguese province of Rio Grande, among the chain of mountains that run along the coast of the Atlantic. Its course is at first to the west, along a high valley, which is separated from the Parana by an elevated ridge, and it receives so many smaller streams that at eighty miles from its sources it is a large river. The great declivity of the ground over which it has passed gives it so much strength, that after emerging from the mountains it overflows the plain to such an extent, that it requires half an hour's time to cross it in a ten-oared boat, though the current is not very strong. After leaving the mountains at the distance of 690 miles from its mouth it flows through a desert country for a considerable length, and then turning to the south it receives an increase from numberless streams, and enters the La Plata, in the 34° of south latitude.
The banks of the Uruguay are romantic and fertile, after it quits the desert and turns southerly: but it is generally a rapid stream, though navigable for vessels two hundred miles from the La Plata; beyond this it can only be ascended by canoes or rafts, as it is interrupted by frequent falls and rapids.
On the southern confines of Buenos Ayres, the plains are drained by the Saladillo, the Hueyque Leuva or Colorado, and the Desaguadero which descend from the Andes of Cuyo: but of these rivers very little is known.
The chief town of this government is Buenos Ayres, which, being the metropolis of the viceroyalty, has been already described.
Monte Video is the next city of note in this province; it is situated on the north side of the La Plata, in a small bay twenty leagues west of Cape Santa Maria, in 34° 54' 48" south latitude, and 56° 14' 30" west longitude, and has its name from a mountain that overlooks the place, and on which is a light-house that has a good view to leeward. Monte Video is a very recent town, and was erected on account of its harbour being one of the best on the coast.
It stands on a gentle elevation at the end of a small peninsula, and is completely enclosed with fortifications. The harbour, which is the best in the La Plata, is shoal, and exposed to the north-east winds.