Page:History of the Periyár project. (IA historyofperiyar00mack).pdf/35

I.] With regard to the second point Captain Pennycuiok proposed a dam with section based on Molesworth's formula and having front and rear faces of solid masonry with longitudinal and cross walls of the same materials, 6 feet thick, the cells formed by these walls being filled with concrete.

These arrangements and the details of construction were objected to as involving risk of unequal settlement, and Captain Pennycuick in later proposals gave the objection due weight. He also reconsidered the question of allowing the freshes to pass over the dam during construction or of passing them under it, and in the event of the latter arrangement being preferred he proposed to form culverts having a waterway of 1,800 square feet so as to reduce the velocity of discharge. This was a matter of importance, since the highest then recorded flood represented a discharge of nearly 50,000 cubic feet a second, involving a velocity even with this area of nearly 29 feet a second. It will be seen that two principles were gradually being established, first that it was practically impossible to prevent the occasional submersion of the dam during construction, and second that this precluded the idea of an earthen dam in any form. At that time large masonry dams were little known to any but French Engineers, and the hesitation in admitting the necessity for one is easily comprehensible.

The Government of Madras wished the whole matter referred to the best English opinion and with this recommendation forwarded the estimates to the Government of India. The latter, however, considered that the experience of Engineers in India in the construction of irrigation works must far exceed that of Engineers of any other country in the world and they offered to appoint a committee of high standing, selected from Bengal, to which an officer of the Madras Public Works Department having complete knowledge of the locality and of the details of the project might be added. This not meeting the views of the Government of Madras, the enquiry into the probable returns of revenue not being completed, and the severe famine of 1876-77 at that time occupying all funds as well as all attention, the matter was temporarily put aside, but meanwhile the Revenue Department continued their enquiries and ultimately reported that an eventual net return of Rs. 5,99,000 per annum might fairly be looked for.

No further action of a practical nature was taken during the ensuing six years; but there was a great deal of desultory discussion, in the course of which the arrangements gradually took a definite and less