PLATE, THE RIVER, or RIO DE LA PLATA (" River of Silver "), in South America (see vol. ii. Plate xxv., and vol. iv. Plate xvii,), was at first known as Rio de Solis, after Juan Diaz de Solis, who discovered it in 1515, and lost his life on its banks. The present name, a double misnomer, was bestowed by Sebastian Cabot, who, ignorant that he was on the wrong side of the continent, thought he had reached a country of mineral wealth----a mistake (perpetuated also in the designation Argentine Republic) which may be said to have received a kind of poetic justification in the fact that the distant mines of Potosi lie within the drainage area of the La Plata system. Like Rio Grande do Sul and Rio de Janeiro on the Brazilian coast, this Rio is not a river but a vast estuary into which rivers discharge. At its narrowest it is 23 miles across, opposite Buenos Ayres 31 miles, and opposite Montevideo 63 miles. By some writers the conventional limit between estuary and ocean is drawn from Montevideo, where the water is still fresh enough to be drunk ; but others go farther out and take the line 150 miles across from Maldonado to Cabo San Antonio. In the former case the length of the estuary is 125 miles. At one time it must evidently have extended 200 miles farther inland to Diamante, at the bend of the Parana ; and nature is steadily and rapidly at work prolonging the rivers proper at the expense of the estuary. At low water the average depth may be taken at 18 feet, and shoals and sandbanks are abundant, especially in the upper end. Nearly the whole expanse between Buenos Ayres and Martin Garcia Island is between 3 and 6 feet deep, and a great portion is even shallower. In the shallower portions the bottom consists of a very fine hard-grained sand, in the deeper portions of a sticky ooze. The tidal movement is so disguised by the more obvious effects of wind that sir Rivy found people who had lived all their lives on the banks ready to deny its existence. But at Buenos Ayres the normal neap-tide is 5 feet 3 inches above ordinary low water, and the spring tides vary from 6 to more than 10 feet. The region being one of "storms and extraordinary electric disturbance," with the pamper() at one time blowing hard from the land and at another a sea wind driving the ocean before it, the ordinary levels and currents are often violently disturbed. The general slope of the surface may even be reversed, and the main current of estuary and river run up stream for a hundred miles or more. It has been estimated that the volume of water poured into the Rio de la, Plata exceeds the aggregate discharge of all the rivers of Europe put together. Nor need this be matter of surprise when the enormous extent and the character of the drainage area are taken into account.. The headwaters of the Rio Blanco (a feeder of the Pilcomayo sub-system) rise only 125 miles from the coast of the Pacific, in 68° 10' W. long., and those of the Rio Grande are not more than 70 miles from the coast of the Atlantic, in 44° W. long.; the basin thus extends east and west over twenty-four degrees of longitude, or 1500 miles, and the direct distance from the northmost source to the mouth of the Parana is about as great. A considerable proportion of this vast area lies within the tropics, and receives an abundant rainfall, which, owing to the character of the strata, is largely carried off by the surface drainage. As an instance of the effect of this rainfall on even the secondary tributaries, Mr Bigg-Wither's experience may be cited : at Jatahy on the Tibagy he was detained from the 2d to the 25th of July by the river, after nine days of incessant downpour, rising 33 feet at a place where it was 200 yards wide, and pouring along a volume of 90,000 cubic feet per second, or twenty-five times its low-water volume (see I OUril. Roy. Geogr. Soc., 1876).

The three great rivers of the La Plata system are the Parana, its equal affluent the Paraguay, and the Uruguay - the second being the most important as a waterway, and the first the most interesting from its physical features.' As the general course of the Parana. and the Paraguay, both of which rise in Brazil, has already been sketched in the article on that country (vol. iv. p. 222), it simply remains to direct attention to a few points of interest. In regard to the great "Seven Falls" of the Parana, we have still no better account than that of Azara in the 18th century ; but the Hundred Cataracts or Victoria Falls of the Curityba or Y-guazu have been described in detail by the members of the first Germano-Argentine colonial land-surveying expedition to Misiones in 1883 (see Verhandl. d. Ges. t. Erdkunde ZU vol. x. pp. :357-364). For combined beauty and grandeur of scenery they claim to rank among the foremost cataracts in the world. About 6 or 7 miles higher up the river is 3 miles broad ; it gradually narrows until, after passing through a perfect labyrinth of islands (King Albert Archipelago), it pours, not in a single mass, but in numerous streams, over a horse-shoe edge of rock into a gorge 120 to 150 feet deep. Niederlein divides the falls into three groups - a northern or Brazilian, a central or insular, and a southern or Argentine, to which he has attached respectively the names of the Emperor Don Pedro, the Emperor William, and General Roca. The river continues for some distance shut in by overhanging cliffs ; and a large number of secondary cataracts (Bosetti Falls, Prince Bismarck Falls, &c.) are formed by tributary streams, and add to the bewildering beauty of the scene.

The watersheds between the north-eastern headwaters of the Paraguay system and the southern affluents of the Amazons are so low and narrow that in some instances canoes have been conveyed overland from the one to the other. Interest has recently been concentrated on the exploration of the Pilcomayo, a right-hand tributary which joins the Paraguay proper in 25° 20' S. lat. Though its sources liave long been known, all attempts to trace it downward from Bolivia or upward from the Argentine Republic o had been foiled by the hostility of the Indians. At length, on April 27, 1882, Dr Crevaux, the great French explorer of South-American rivers, was slain with all his party by the Tohas at a place called Ipanticapu. General interest was thus aroused ; and the task in which Dr Crevanx perished has since been practically accomplished by Dr Thouar, his fellow-countryman, who, leaving the San Francisco mission-station on 10th September 1883, reached the mouth of the river on 10th November, though he had not been able to keep close to its course in the lower section of the journey. The Pilcomayo risos in Vilcapujia (a mountain 13,500 feet high to the E. of Lago l'oopo), and passes between the Cordillera of Livielinco and the Cordillera de los Francs, a few miles to the north of Potosi. It cuts through the last range of the Andes in 21" 16'50" S. lat. and 63° 25' W. long., and enters the plains of the Gran Chaco at a height of 1456 feet above sea-level (J. B. ,Minehin 2). It is soon after joined by the Pilaga, which brings down the waters of the Rio Blanco and other streams from the mountains. Till in its south-eastern course it reaches 22° S. lat., the river has a very regular course, flowing at the rate of 6500 feet per hour over a sandy bed 600 to 700 feet wide, unimpeded by rocks or trees, and enclosed by steep banks 15 to 20 feet high, above which the country stretches out in pasture-covered plains. Farther down the banks increase in height to from 20 to 45 feet, and embrace a channel or valley 5500 feet or more in breadth, though the actual river does not exceed 150 or 200 feet. At the point called Cabello Muerto, 24° 20' S. lat., commence the marshy plains of the lower course, in which time banks hardly rise above the level of the water, and a whole series of lagoons lie at a distance of a mile or two on the left hand. So flat is the country, and so tortuous time river that when Robinson, in 1873, ascended for 150 miles, he never lost sight of the white houses of Asuncion.3 About 150 miles below time mouth of the Pilcomayo the Paraguay is joined by another Andean river the Rio Yermejo or Y-pyta, whose red waters, pouring into the dark clear water of the main stream, are sufficient to tinge the whole current downwards to the confluence of the Parana. "From the junction of its headstreams down to the Paraguay, the Verinejo does not receive a single affluent ; its breadth varies from 70 to 250 yards, its depth from 5 to 16 feet ; and the current appears to average 1 miles an hour" (Keith Johnston). Its navigability was shown about 1730 by the Franciscan missionaries Murillo and Lapa descending the Whole way in a canoe, but it was not till 1874 that, under Don Natalio the regular navigation was undertaken.

At their confluence the Paraguay has a width of half a mile, the Parana. of 3 miles. The united river continues for 686 miles, first in a south-south-west, then in a south, and finally in a south-east direction before it reaches the head of the La Plata estuary. Down to Diamante, or for 433 miles, its left bank is at intervals formed by lines of bold bluffs from 100 to 200 feet high, on which several of the more important towns are built ; but the channel often breaks up so as to enclose extensive islands. The worst reach in this respect is time 45 miles below Goya, a little town in 29° 7' S. lat. At Diaznante begins the enormous delta (some 5000 or 6000 square miles) which is traversed by countless and changing channels, and presents nothing else, even if viewed from the masthead of the steamer, but a boundless labyrinth of islands clothed with exuberant vegetation. The two chief tines of navigation through this deltaic region are the Parana, de las Palmas (so called by Cabot, in 1526, but now showing comparatively few palms among its ceibos, willows, and poplars) and the Parana Guam. The former has its month about 24 miles north of Buenos Ayres, the latter joining the estuary of the Uruguay 22 miles farther north, in 34° N. lat. and 58° 24' 30" W. long.

The third great confluent of the La Plata system, the Uruguay, is quite unlike the other two. Instead of having a fairly steady and continuous flow, it appears sometimes as an insignificant torrent and at other times as a magnificent river. It has its heath\ aters in the Serra Gera], and for several hundred miles continues to flow west through Brazil (forming the northern boundary of Rio Grande do Sul province), as if it meant, like the Curityba, to early its waters to the Parana; but about 54° W. long. it is turned aside by the mountain range of Misiones, and flows south-west and south almost parallel with the Parana. It has a total length of 950 miles, and a drainage area of 200,000 square miles.

In the matter of annual rise and fall the three rivers differ considerably. The Paraguay is regular, reaching its lowest stage in the end of February, and its highest about the end of June, and showing an average difference of level not exceeding 15 feet. The ordinary flow at Asuncion is between 97,400 and 99,950 cubic feet per second. Above the junction of the Paraguay the Parana appears to have numerous and rapid risings at irregular intervals, but to reach its maximum in December. Below time junction it has much the same movement as the Paraguay, having high water in sumsuer, gradually shrinking through September, October, and December, flooding in January, and continuing high and steady till June. The Uruguay rises about the middle of January (at Salto sometimes 22 feet above low water); again in April, to continue in flood for two months (30 feet at Salto); and for the third time, and with great regularity, in September or October, to last a whole month, and reach 40 to 50 feet above low water. Occasionally the flood o level of the Parana is maintained throughout a whole year, or even two years in succession ; and at intervals, as in 1858 and 1868, the water rises so high that the whole delta is submerged. The highest floods on record stood 24 feet above ordinary low-water mark at Rosario, or 12 feet above ordinary high water. As a system of waterways the La Plata rivers are but partially developed. Steamers, mainly Brazilian, ascend from Buenos Ayres by the Parami, Paraguay, and Cuyaba, a total distance of 2146 miles, to the town of Cu3almi in Brazil ; and the Pilcomayo and the Vermejo, the Apa, the Jejuy, and the 'l'ebiquary are all more or less navigable. The Parana affords a free passage for 280 miles above the confluence to the Seven Falls, except during low water, when the rapids of Apipe interfere; and, according to Bigg-Wither, the upper Parana and its tributaries the Tibagy, 1'aranapan6na, Tiete, lbnhy, &c., furnish 1290 miles of navigable stream, of which 510 could be at once utilized by steamers of light draught, while the remainder would require a certain outlay in the way of improvements. Vessels drawing 4& feet of water can always ascend the Uruguay to Salto (200 miles), and during six months they can cross the Salto Chico, or Lesser Fall, a mile higher up; but the Salto Grande, 8 miles farther, stops all progress except during six weeks in October and September. The whole system may be estimated to give upwards of 5000 miles of waterway, of which 3500 are accessible front the sea, without counting the secondary deltaic channels.

See T. S. Page, U.S La, Plata, 1559 (the surveys of the " Waterwiteh "); Burton. nattie -fields of Paraguay,ls70; Bigg-Wither, Pioneering in South Brazil, I57 ; Bevy, HydraulicA (treat Rivers: the Paranti, the Uruguay, and the La Plata Eat !tarn, 1871 (a series of elaborate investigations and measurements of great value); and other works mentioned under PARAGUAY. A. W.)