The Black Sea in fact receives more water from rivers than the Mediterranean, and the same author observes, "the greatest rivers in Europe fall into the Black Sea, by means of the Danube, in which the rivers of Suabia, Franconia, Bavaria, Austria, Hungary, Moravia, Corinthia, Croatia, Bothnia, Servia, Transilvania, Wallachia, empty themselves; those of Black Russia and Podolia, go into the same sea by the Niester; those of the southern and eastern parts of Poland, of the northern parts of Muscovy, and the country of the Cossacks, enter therein by the Neiper or the Boristhenes; the Tanais and Copa also fall into the Black Sea by the Cimmerian Bosphorus; the rivers of Mingrelia, of which Phasis is the principal, also voids itself into the Black Sea, as does the Casalmac, the Sangaris, and other rivers of Asia Minor which have their course towards the north; nevertheless the Thracian Bosphorus, which is the only outlet from it, is not comparable to any of these great rivers."
These facts prove, that evaporation alone carries off a very considerable quantity of water, and it is from this great evaporation from the Mediterranean that the ocean continually flows thither through the straits of Gibraltar. It is difficult to estimate the quantity of water any sea receives; we should be acquainted with the breadth, depth, and rapidity of all the rivers which enter therein, how much they increase and diminish in the different seasons of the year, and how much it loses by evaporation; the last of which is most difficult; for even supposing it proportional to the surfaces, it must be more considerable in a hot than in a cold climate; besides, water mixed with salt and bitumen, evaporates more slowly than fresh water; a troubled sea more quickly than one that is tranquil; and the difference of depth has also some effect: in short, so many circumstances enter into this theory of evaporation that it is scarcely possible to calculate any exact estimations on it.
The water of the Black Sea appears to be less clear and less saline than that of the ocean. There are no islands in it, and its tempests are more violent and more dangerous than in the ocean, because the whole body of its waters being contained in a bason, which has but a small outlet, when they are agitated, they have a kind of whirling motion which strikes the vessels on every side with an insupportable violence.
Next to the Black Sea the greatest lake in the universe is the Caspian Sea, whose extent in length from north to south is about 300 leagues, and scarcely more than fifty broad. This lake receives the Wolga and some other considerable rivers, as the Kur, the Faie, and the Gempo; but what is singular, it does not receive any on its eastern side; the country on that side being only a desert of sand almost unknown. Czar Peter I. sent some engineers there to design a chart of the Caspian Sea, who discovered that its figure was quite different from that given by former geographers, who had represented it to be round, whereas it is very long and narrow. The eastern coasts of this sea, as well as the neighbouring country, were unknown: even the existence of lake Aral, which is 100 leagues distant from it towards the east, was doubtful, or at least thought to be a part of the Caspian Sea, so that before the discoveries of the Czar there was unknown land in this climate upward of 300 leagues long by 100 or 150 broad. Lake Aral is nearly an oblong, and may be 90 or 100 leagues long, by 50 or 60 broad; it receives two very considerable rivers, the Sideroias and the Oxus, but as well as the Caspian has no outlet for its waters; and it bears the further resemblance, for as the Caspian receives no river on the east, so lake Aral receives none on the west, from which we may presume, that formerly these two lakes were but one, and that the rivers having, by degrees, diminished, left a great quantity of sand and mud, and which forms the country that now divides them. There are some small islands in the Caspian, and its waters are much less saline than those of the ocean; storms are here very dangerous, and large vessels are not used in it for navigation, because it has many sand banks, shoals and rocks scattered under the surface of the water. Pietro della Valle says, "The largest vessels employed on the Caspian Sea, along the coasts of Mazanda in Persia, where the town of Ferhabad stands, although they are called ships, appear smaller than our Tartanes. Their sides are high, and they draw but little water, having a flat bottom. They give this form to their vessels, not only because this sea is shallow, but because it is filled with shoals and sand banks; so that if the vessels were not fabricated in this manner they could not be used with safety. Indeed, I was astonished, why at Ferhabad they fish only for salmon, which are found at the mouth of the river, some poor sturgeons, and other sort of fresh water fish, of little value: I attributed the cause of it to their ignorance of the arts of fishing and navigation until the Cham of Esterabad, whose residence is at a sea port, informed me that the waters are so shallow 20 and 30 leagues from shore that it was impossible to cast the nets with the chance of taking any fish, and that it was for this reason they gave the above-mentioned form to their vessels, which are not mounted with any cannon, as but few corsairs and pirates ever visit this sea."
Struys and other travellers have asserted, that in the neighbourhood of Kilan, there were two gulphs wherein the rivers of the Caspian were ingulphed, and carried afterwards by subterranean canals into the Persian Gulph. De Fer and other geographers have even marked out these gulphs in their maps, nevertheless we are assured by the people sent by the Czar that they do not exist.[B]
[B] See Mem. Acad. Sciences, 1721.
The circumstance of willow leaves being seen in great quantities on the Persian Gulph, and which are supposed by the same authors to come from the Caspian Sea because there are no such trees on the Persian Gulph, is fully as improbable as their subterraneous gulphs, and which Gemelli Careri, as well as the Muscovites, asserts are entirely imaginary: in fact, the Caspian is near one third smaller than the Black Sea, which last also receives much more water by rivers than the former: the evaporation therefore is sufficient to carry off all its water, nor is it necessary to suppose subterraneous gulphs in the Caspian any more than in the Black Sea.
There are lakes which do not receive any rivers, and from which none go out. There are others which both receive and discharge and some that only receive them. The Caspian Sea, lake Aral, and the Dead Sea, are of the last kind; they receive the waters of many rivers, and contain them. In Asia Minor there is a small lake of the like kind, and one much larger in Persia, on which the town of Marago stands; its figure is oval, and it is about ten or twelve leagues long, by six or seven broad; it receives the river Tauris, which is not very considerable. There is also a similar small lake in Greece, about 12 or 15 leagues from Lepanto, which are the only lakes of that kind known in Asia. In Europe there is not one which is considerable; in Africa there are many small ones, as those which receive the rivers Ghir, Zez, Touguedout, and Tasilet. These four lakes are pretty near each other, and situate towards the frontiers of Barbary near the deserts of Zara; there is another situated in the country of Kovar, which receives the river of Berdoa. In North America, where there are more lakes than in any other part of the world, not one of this kind is known, at least if we except two small collections of water formed by rivulets, the one near Guatimapo, and the other some leagues from Realnuevo, both in Mexico. But in South America, at Peru, there are two contiguous lakes, one of which, lake Titicaca, is very large, and receives a river whose source is not very remote from Cusco, and from which no river issues: there is one smaller in Tucuman, which receives the river Sala; and another larger in the same country, which receives the river Santiago, and three or four others between Tucuman and Chili.
The lakes which receive no rivers, and from which no rivers issue, are greater in number than those just spoken of; these lakes are kinds of pools where the rain water collects; or may proceed from subterraneous waters, which issue in form of springs, in low places, where they cannot afterwards find any drain. The rivers which overflow may likewise leave stagnate waters in the country, which may remain for a long time, and only be replenished by other inundations. The sea has often inundated lands and formed saline lakes therein, like that at Haarlem, and many others in Holland, to which, no other origin can be attributed; or by losing its natural motion, might quit some land, and leaving water in the lowest places may have formed lakes, which have continued to be supported by rains. In Europe there are many small lakes of this kind, as in Ireland, Jutland, Italy, in the country of the Grisons, Poland, Muscovy, Finland, and in Greece. But all these lakes are very inconsiderable. In Asia there is one near the Euphrates, in the desert of Irac, more than 15 leagues long: another in Persia nearly of the same extent, and on which the towns of Kelat, Tetuan, Vastan, and Van, are situated; another small one in Chorazan near Ferrior; another in Independent Tartary, called Lake Levi; two in Muscovy Tartary, another in Cochinchina, and one in China very large, and not far distant from Nankin; this last, nevertheless, communicates with the adjacent sea, by a canal several leagues in length. In Africa there is a small lake of the same kind in the kingdom of Morocco; another near Alexandria, which appears to have been left by the sea; another very considerable one formed by the rain in the desert Azarad, about the 30th degree latitude; this lake is eight or ten leagues long; another still larger on which the town of Gaoga is situate, in the 27th degree; another much smaller, near the town of Kanum, under the 30th degree; one near the mouth of the river Gambia; many more in Congo, about the 2d or 3d degree of south latitude; two more in the country of the Caffrees, one called the Lake Rufumbo, of no great length, and another in the province of Arbuta, which is perhaps the greatest lake of this kind, being about 25 leagues in length by seven or eight in breadth; there is also one of these lakes at Madagascar, near the east side, about the 29th degree of south latitude.
In America there is one of these lakes in the middle of the peninsula of Florida, in its centre is an island called Serope; the lake of Mexico is also of this kind, this is almost round, and about 10 leagues diameter; there is another still larger in New Spain, 25 leagues distant from the coast of Campeachy Bay, and another smaller in the same country near the coast of the South Sea. Some travellers have asserted that there was in the inland parts of Guiana a very great lake of that kind; it is called the Golden Lake, or Lake Parima. They have related surprising things of the riches of the neighbouring country, and of the quantity of gold dust that is found in this lake. They give it an extent of more than 400 leagues in length, and 125 in breadth. No river, they say, goes out nor enters therein; although many geographers have marked this lake in their maps, it is not probable there is any such existing.