ated the great Sugar Estates, an account of which is given, in part, in the Third Section of the First Book.
The most interesting object in the valley of Mexico is the vast system of drainage, by which the Capital is protected against the periodical inundations of the lake of Tĕzcūcŏ, which, during the two first centuries after the conquest, threatened it repeatedly with destruction. Of this system the third Book of Baron Humboldt's Essai Politique contains a description, given with all the accuracy which distinguishes the works of that scientific traveller, upon every point to which his personal observations extended; and to this I must refer my readers for details, many of which will be found to possess the highest interest. I shall only attempt here to mention a few of the leading facts, in order not to leave entirely unnoticed a subject so worthy in every sense of attention. The valley of Tenochtitlan, or Mexico, forms a vast basin, which, although it is situated at an elevation of about 7,000 feet above the level of the sea, serves as a receptacle for the humidity, which filtres from every part of the lofty ridge of porphyritic mountains by which it is surrounded.
Not a single stream issues from the valley, with the exception of the Arroyo of Tĕquīsqŭiăc, but it receives the waters of the rivers Păpălōtlă, Tĕzcūcŏ, Tĕŏtĭhuăcān, Guădălūpĕ, Păchūcă, and Gūāūtĭtlān, by the accumulation of which the four great lakes of Chalco, (and Xochimiko,) Tezcuco, San Crĭstōbăl,
