After the flood of 1607, the tunnel of Huehuetoca was undertaken, and constructed in eleven months, for the purpose of letting out of the valley the waters of the River Guautitlan, so as to prevent it from falling into Tezcuco or flooding the city.

It became necessary to alter this state of things, and a passage was cut at a place where the hills were but little above the level of the highest lake. The history of this passage, the famous "Desague de Huehuetoca," is instructive enough, but it has been written so threadbare that I cannot touch it.

This, and the horrible battle of Otumba, which Cortéz fought a little way east of this spot, are memorable events in the history of Mexico more memorable than they deserve to have been. As we rode along the eastern rim of the valley, the sun was shining brightly on the western hill that inclosed it. The opening made by the canal of Huehuetoca was plain in sight.

I had, after careful inquiry and observation, come to the conclusion that the marshes of the valley of Mexico were, in the time of Cortéz, substantially in the condition in which we find them at the present day; that the filling up they had undergone in that time was counterbalanced by the relief they had gained by the canal of Huehuetoca.

The grand Canal of Huehuetoca. The Silver Mines of Pachuca. Hakal Silver Mines. Real del Monte Mines. The Anglo-Mexican Mining Fever. My Equipment to descend a Mine. The great Steam-pump. Descending the great Shaft. Galleries and Veins of Ore. Among the Miners one thousand Feet under Ground. The Barrel Process of refining Silver. Another refining Establishment.

The city looked like this some two hundred years ago, when Martinez the engineer tried an unfortunate experiment with his draining tunnel at Huehuetoca, and flooded the whole city for five years.

Nor could the Lagunas or Ponds have been much deeper. The Brigantines only flat-bottomed Boats. The Causeway Canals fix the size of the Brigantines. The Street Canals. Stagnant Water unfit for Canals. The probable Dimensions of the City Canals. Difficulties of disproving a Fiction. A Dike or Levee. The Canal of Huehuetoca. The Map of Cortéz. Wise Provision of Providence.