Its greatest length, from the mouth of the stream of Tenango in the lake of Chalco, to the foot of the Cerro de Sinóc, in the neighborhood of the canal Huehuetoca is 19½ leagues, and its greatest breadth, from San Gabriel at Tezcoco, to the sources of the river Acapusalco at Quisquiluca, is 13¼ leagues. Its area is 258 3/8 square leagues, 23 1/3 of which are covered by lakes. On the south, east, and west, the mountains maintain a probable average height of 10,000 feet above the sea, while at the north their depression is considerable, and through the gaps and vallies the waters of the lakes are discharged towards the Gulf of Mexico.
Six great highways centre in the capital, and leave it to traverse the principal districts of the confederacy.
1st. The road to Acapulco on the west coast, which passes out of the valley over its southern rim of mountains at the point known as the Cruz del Marquez, about 2,284 feet above the city of Mexico, or 9,784 above the level of the sea.
2d. The road to Toluca, by Tianguillo and Lerma.
3d, The road to Queretaro, Durango, &c. called El Camino de tierra adentro, which leads across the eminences at the north of the valley, by an elevation of about 100 feet only above the level of the lakes. This road is the highway for the internal trade of Mexico with the northern provinces.
4th. The road to Pachuca and Real del Monte in the mining district, across the Cerro Ventoso.
5th. The road to Puebla, across Bonaventura and the plains of Apam.
6th. The new road to Puebla and Vera Cruz, by Rio Frio and San Martin, across the northern shoulder of the volcano of Popocatepetl. It greatest elevation is at the barranca or ravine of Juanes, 10,486 feet above the level of the sea. Besides the two last mentioned roads there is a third, between the volcanoes of Popocatepetl and Iztaccihuatl, by Tlamanalco, Ameca, La Cumbre, and Cruz del Correo, passing out of the valley of Mexico into those of Cholula and Puebla.
Five lakes are embosomed in the valley in the immediate neighborhood of Mexico:—
1st. The lake of Zumpango, is the northernmost, and has an area of about 1¼ square leagues. A dam, called La Calzada de la Cruz del Rey, divides it into two basins, the westernmost of which is known as the Laguna de Zilaltepec, and the easternmost, the Laguna de Coyotepec. It is 26 feet higher than the mean level of the lake of
