great inundations, in spite of the gradual decrease of the waters of Lake Tezcuco, from causes which I have hinted at in the first page of this letter.
The attention of the Spanish viceroys being thus imperatively drawn to the subject, about the commencement of the seventeenth century, a scheme was formed by a Spanish engineer, Enrico Martinez, by the execution of which, the surplus waters from the two upper lakes to the northward—San Cristobal and Zumpango—were to be drawn off in another direction; their basins being the most liable to overflow, from the character and size of their tributaries.
The comparative depression and narrowness of the mountain rampart, hemming in the valley to the northward, in the vicinity of Lake Zumpango, favoured the project of constructing a tunnel by which this should be affected, forming a duct through which all the waters rising above a certain level should be conveyed into the bed of the river Tula, the main branch of the Panuco, whose source lay on the other side of the ridge, and which you will recognise as entering the gulf at Tampico.
This great work was commenced in 1607, and in the course of its prosecution by the hand of the native Indians, hundreds are said to have perished by the caving in of the earth and other casualties. But what was that? the work was to be done, and if Indians were wanted, a party of horsemen armed with the lasso was sent out to the distant villages, and the poor natives were secured and brought to the scene of toil like so many wild horses.
The memory of what their ancestors endured at Huehuetoca, both at this epoch and in after times, is not forgotten by the present race.
A tunnel or subterranean gallery was at length finished, 20,000 feet in length: but, in 1629, the stoppage of the passage by the fall of the roof, or other casualty, combined with a season of unusual flood, caused such a rise in the waters of Lake Tezcuco, that the whole of the ancient bed, and the streets of the capital itself, with the exception of the very highest levels, were covered with