About thirty miles below the mouth of the Vermejo the Paraguay is joined from the east by the great river Paranã, which name it thence takes till it is finally lost in the Rio de la Plata. This river, rivalling in extent the Paraguay itself, rises in the mountain-chains to the north-west of Rio de Janeiro, in latitude 21°. Turning first westward, and afterwards towards the south, it is increased by several large rivers, amongst which the most noted are the Paranaiba, the Tieté, the Paranapané, and the Curitava. On reaching the Guarani Missions, near Candelaria, in about lat. 27° 30´, it turns again westward, and runs with little deviation from that parallel till it falls into the Paraguay. Thence these two mighty rivers, mingling their waters flow on in one vast and uninterrupted stream, gradually increased by many rivers of minor importance, which join it from either side, till they finally empty themselves through a well-defined delta into the estuary of La Plata.
The extent of the practicable navigation on the two great branches of this mighty river varies with the geological formation of the countries through which they respectively pass.
The Paranã, whilst running through the mountainous districts of Brazil, is broken by many falls above the Guarani Missions, especially one called the Salto Grande, in lat. 24° 4´ 58" (as fixed by the officers of the Boundary Commission in 1788), where the river, which immediately before is nearly a league across, becomes suddenly confined by a rocky pass not more than sixty yards in width, through which it rushes with inconceivable fury, and forms a splendid cataract, between 50 and 60 feet high, dashing down with such thundering noise that it is said to be heard at a distance of five or six leagues. For a hundred miles afterwards, as far as the mouth of the river Curitiba, in lat. 25° 41´, the river is nothing but a succession of falls and rapids.
The Paraguay, properly so called, on the contrary, may be passed up by vessels of some burthen the whole way[52] to the Jaurú, in latitude 16° 25´, presenting the extraordinary extent of an uninterrupted inland navigation of nearly nineteen degrees of latitude, calculating the straight distance north and south, throughout the whole of which there is not a rock or stone to impede the passage, the bottom being everywhere of clay or fine sand. The least depth of water is in the channels through the delta by which it discharges itself into the Plata, but in the passage called the Guazú (the great canal) there is seldom less than two and a half fathoms.
The upper part of the river is extremely picturesque, and its shores abound in all the varieties of an intertropical vegetation. The palms particularly are remarkable for the magnificence of their growth. Below the junction of the Paranã it is thickly studded with islands covered with wild orange-trees, and a variety of beautiful shrubs and parasitical plants, new to European eyes.
It has been remarked that there is a great resemblance in the periodical risings and inundations of the Paraguay and those of the Nile, and there is certainly a striking analogy between the two rivers in many respects. Both rise in the torrid zone, nearly at the same distance from the equator, and both, though holding their courses towards opposite poles, disembogue by deltas in about the same latitude; both are navigable for very long distances, and both have their periodical risings, bursting over their natural bounds, and inundating immense tracts of country.
The Paranã begins to rise about the end of December, which is soon after the commencement of the rainy season in the countries situated between the tropic of Capricorn and the equator, and increases gradually till the month of April, when it begins to fall something more rapidly until the month of July. There is afterwards a second rising, called by the natives the repunte; but this, though regular, is of no great consequence, the river never overflowing its banks. It is probably occasioned by the swelling of the rivers from the winter rains in the temperate zone.
The extent of these periodical risings is, of course, in some degree, regulated by the quantity, more or less, of rain which may fall during the corresponding season; but, in general, the inundation takes place with great regularity, the waters rising gradually about twelve feet in the bed of the river in four months; this is the ordinary average of the increase of the river after its junction with the Paraguay; though above it, at Assumption, where the river is much confined, the rise is said to be sometimes as much as five or six fathoms.
The year 1812 was remarkable for the greatest flood in the memory of the natives. Vast quantities of cattle were carried away by it, and when the waters began to subside, and the islands which they had covered became again visible, the whole atmosphere for a time was poisoned by the effluvia from the innumerable carcases of skunks, capiguaras, tigers, and other wild beasts which had been drowned on them. On such occasions it frequently happens that the animals, to save themselves, swim off to the floating masses of canes and brushwood (called by the Spaniards "camelotes"), and are thus carried down the river, and landed in the vicinity of the towns and villages upon the coast. Many strange stories, are told of the unexpected visits of tigers so conveyed from their ordinary haunts to Buenos Ayres and Monte Video. One in my time was shot in my own grounds near Buenos Ayres, and some years before no less than four were landed in one night at Monte Video, to the great alarm of the inhabitants when they found them prowling about the streets in the morning. In the swampy region of Xarayes, where the inundation commences, the ants, which are in vast numbers there, have the sagacity to build their nests in the tops of the trees, far out of reach of the waters; and these nests are made of a kind of adhesive clay, so hard that no cement can be more durable or impervious to the weather.
During the inundation the river is exceedingly turbid, from the great quantity of vegetable substances and mud brought down by it:—the velocity of the stream in the higher and narrower parts of the river at first prevents their deposition, but as it approaches the lower lands, or pampas, where it overflows its bed, these substances are spread over the face of the land, forming a grey slimy soil, which, on the abatement of the waters, is found to increase vegetation in a surprising degree.