Page:Vol 6 History of Mexico by H H Bancroft.djvu/688

668 would lose thereby its present importance as a large river. This objection is met thus: Abreast of Minatitlan, the cross-section of the river has an area of 31,900 square feet, and though the velocity of its current is always more than 1.6 feet per second, even taking it at one foot per second, this would give nearly 32,000 cubic feet of water per second, as the delivery of the river. One twentieth of this amount is taken for canal purposes, and is obtained near its source, and before any of its large tributaries swell the mighty volume of the river. While the diminution occasioned by subtracting so small a volume from the river will be less perceptible than the fluctuations produced by small freshets, this small amount will be sufficient to supply one half of the canal necessities, and to irrigate the sterile lands of the Pacific plains, where the indigo culture languishes for want of water. Besides, when the canal shall have been built, the valley of the Coatzacoalcos will assume its commercial and political importance. At present it is valueless, and the river can hardly be ascended as far as Suchil in Indian canoes.

Having demonstrated that there is an abundant supply of water to feed the summit-level and the whole canal, I will now proceed to describe the feeder route, and the practicability of bringing the water to the summit. The feeder route is divided into five sections.  First Division. — The feeder will follow the left bank of the Blanco and Corte rivers, until it reaches the Capepac River. The whole of this division will be in side-cuttings, with very little filling, and only three inconsiderable full cuts. The ground was explored at the points marked with dotted lines. The topography is accurately sketched.

The most important stream crossed is the Maxiponac (Sardine Brook), insignificant as to volume, and remarkable for the number of its beautiful falls. Sandstones and clay are abundant, feldspars crop out in many spurs, and the excavations will be difficult and expensive. The approximate length of this division, including the Blanco Cut, is four and one eighth (4) miles.

Second Division. — From the Capepac (Reed Brook), the feeder will commence at Lemon Ridge, at the proper grade; and following the Capepac Valley on the left bank of its western branch, it will extend nearly to its head-waters; 227 feet above the bed of the Capepac, it will be necessary to construct an aqueduct about 1,200 feet long, connecting the Lemon and Devil's ridges. The western portion of this division ends at the gap which forms the water-shed divide of the Milagro and Capepac rivers. Midway between their sources, and at right angles with their direction, flows the Sona-pac (Lemon Brook), traversing the divide, and having its source at Cliff Ridge. The bed of the Sona-pac is 118 feet above the summit; and the width of the gap is 4,150 feet at the grade; therefore a tunnel of that length becomes here indispensable.

The nature of the soil is sandstones at the Lemon Ridge, clay and slates in the upper branch of the Capepac, and marbles at the tunnel. The length of this division is one and a third miles, including the tunnel and the aqueduct. This will be the most expensive portion of the whole route.

Third Division. — This division extends from the tunnel, near the source of the Milagro, to the second ford of the river Pita (Hemp River). It follows the left bank of the Milagro on the lap of the main range, which extends from Cliff Ridge to Tarifa.