lowest portion of its bed, thence through Lake San Cristóbal to Lake Zumpango, whence it was to extend to a tunnel to be opened through the hills that close the valley on the north, giving exit to the water into the barranca of Tequisquiac.[1] For nine years the work proceeded with more or less vigor, when Garay, having been appointed director-in-chief of the valley drainage, called attention to the fact that his original plan had been deviated from, and laid a new project before the government, in which he proposed that the tunnel and the cutting in the barranca should be abandoned, and another tunnel opened into the ravine of Ametlac.[2]
Garay's project met with approval. It included an extensive system of navigable canals and irrigating ditches, all discharging into main arteries connected
- ↑ The length of the Grand Canal was 48,300 metres, or nearly 30 miles; that of the tunnel, 4,954 metres, that is, six miles, less a few yards. At the debouchure of the tunnel, at the barranca of Tequisquiac, was a cutting nearly one and a half miles long, and 92 feet in depth at its deepest part. Iex., Jiem. Foment., 1868-9, 281-2; Id., 1873, 93-4. The plan of conducting the canal to the cutting of Nochistongo, as begun by Iturrigaray, was abandoned, and the construction was carried along the opposite side of Lake Zumpango. Preparatory work had been commenced by Maximilian, and Garay's original plan changed with regard to direction. This initial error was not corrected during the following decade, and much labor and money were thrown away. Palacio, Mem. Foment., 1876-7, 379.
- ↑ The first tunnel opened into the ravine of Acatlan, which led into the barranca of Tequisquiac. The Ametlac tunnel would be more than one mile -1,644 metres — shorter than that by Acatlan, and the cutting 1,522 yards shorter. The Garay project was, moreover, superior in other respects, namely, in direction and in the termination of the work in a fall-an advantage which prevented obstruction to the outflow by floods in the ravine, to which the Acatlan tunnel would be liable. But the Acatlan cut had already been finished, and 410 yards of preparatory tunnelling done, besides the opening of 24 shafts, 4 of which had been sunk to the required depth. The question to be decided was, whether the Ametlac project would cost the same or a less amount than the completion of the work already commenced, under the supposition that the tunnel should be of the same dimensions as the Acatlan one. But Garay went further; he argued that the dimensions adopted by the government would be insufficient for the result expected; namely, the total drainage of the valley. The section of the Acatlan tunnel was only 6.44 square metres; he proposed that that of the Ametlac tunnel should be 21.10 square metres, capable of discharging 36 cubic metres of water per second, or four times the quantity that could be discharged by the smaller tunnel. The cost of the Acatlan tunel he estimated at $446,130, that of the one he proposed by Ametlac at $744,300, showing a difference of $298,170; but by the expenditure of this additional sum the perfect drainage of the valley, he maintained, would be accomplished. See his reports, in Mex., Mem. Foment., 1876-7, 373-4, 378-81.
