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of the water, which seemingly extended far on the other side, up to the very base of the rock of Chapultepec, and of the mountains behind. The Peñon de los Baños appeared once more as an island; and this, which was now a deceptive and unreal picture, was the fact three hundred years ago.

The phenomena exhibited by the lakes of Mexico are extremely interesting.

Though indisputably the hand of man has done much towards the altered state of things as far as regards the diminution of water in the lakes, yet it is probable that natural causes, tending to the same results, have been in operation for ages; perhaps, ever since the day when the cessation of violent volcanic convulsions left the basin and table land of Mexico, with all its chaotic parts, fluid or solid, to the sway of the ordinary and more gentle operations of nature.

It is improbable that there was ever a regular influx of water, from whatever source it may have proceeded, at all commensurate with the great evaporation which, under the influence of the climate, and the physical construction of the country, must always have taken place.

Of the five lakes of Mexico—Tezcuco, Xochimilco, Chalco, Cristobal, and Zumpango—that of Tezcuco is the largest, the most central, the most impregnated with saline particles, and lies at the lowest level.[1] Not one of them possesses a natural outlet from the valley of Mexico; and in case of the overflow of any of the four lakes, Tezcuco is the only reservoir into which they can disembogue themselves. The streams falling into Tezcuco, Xochimilco, and Cristobal, are so inconsiderable as to be of little or no account; but both Chalco at the southern, and Zumpango at the northern extremity of the chain, receive streams of a considerable volume, calculated, under a combination of causes, to throw so large a body of water into their respective reservoirs, as to produce a most extraordinary overflow, and a consequent rise of the waters in Lake Tezcuco. Such, tra-

  1. At the height of 7,468 feet above the sea.