again, raised suddenly more than a vara above their usual level, and prevented from extending themselves to the east and south-east, by the rapid rise of the ground in that direction, rush back towards the capital and fill the streets which approach nearest to their own level. This was the case in the years 1553, 1580, 1604 and 1607, in each of which years the capital was entirely under water, and the dykes which had been constructed for its protection destroyed."3
Such is a topographical sketch of the country accurately given by a careful writer; and to protect an important region so constantly menaced with inundation, the viceroy now addressed himself. Accordingly he commissioned the engineer Enrique Martinez, in 1607 to attempt the drainage of the lake of Zumpango, by the
stupendous canal now known under the name of the Desague de Huehuetoca.
"The plan of Martinez appears to have embraced two distinct objects, the first of which extended to the lakes of Tezcoco and San Cristoval, while the second was confined to the lake of Zumpango whose superfluous waters were to be carried into the valley of Tula by a subterraneous canal into which the river Guautitlan was likewise compelled to flow. The second of these projects only was approved by the government; and the line of the canal having been traced by Martinez between the Cerro or hill of Sincoque and the hill of Nochistongo to the north-west of Huehuetoca, where the mountains that surrounded the valley are less elevated than in any other spot,—the great subterraneous gallery of Nochistongo was commenced on the 28th of November, 1607. Fifteen thousand Indians were employed in this work, and as a number of air shafts were sunk, in order to enable them to work upon the different points at once, in eleven months a tunnel of six thousand six hundred metres 4 in length, three metres five in breadth and four metres two in height, was concluded.