India in 1880

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1881 Excerpt: ...Panjab, from which a canal might perhaps be taken; some smaller rivers which flow through Native States and of which the capabilities are not known; the rivers in the humid regions of lower Bengal where it is drainage that is wanted rather than irrigation; and the Brahmaputra river and its affluents, the Megna and others, which are not likely ever to supply canals for irrigation. In the construction of these works two main principles are adopted, which differ from each other according to the variety of physical circumstance, and which have at times been subjected to much professional controversy. In the north, the rivers are fed from sources arising in the perpetual snows of the Himalayas, and have in the winter season, generally called the cold weather, a volume of water which, though much shrunken in comparison with the summer supply swollen with the rains and the melted snow, is yet considerable. It is this volume of water which the engineers desire to carry off almost in its entirety for fertilization, using Chap. Xiv. HEAD-WORKS OF THE GREAT CANALS. 255 only a portion of the summer supply according to convenience. At the points where the river issues from the mountains and enters upon the plains, the ground is undulating, or even somewhat hilly and often has a rapid slope. Unfortunately for the engineers, the Himalayas have not great lakes at their base, like the Alps on their Italian side, which serve as natural reservoirs of water whence canals can be drawn. Therefore the engineers excavate the channel in the steep banks and sides of the rivers, carrying it across the rugged beds of tributary torrents. These operations relate to what are called "the head-works." The river is thus led into its new channel, which, passing through the rough gr...