THE RIVER IMPROVEMENT WORKS.

Westport Times, Volume IV, Issue 640, 2 April 1870, Page 2

THE RIVER IMPROVEMENT WORKS.

(To the Editor of the Westport Times.)

Sib— The difficulty that seems to exist in getting anything done for the place by the Nelson Government will, I trust, be sufficient excuse for me trespassing on your space. Tenders are, in your last issue, called for the delivery of 4000 tons of stone. Now, sir, if, before any works are commenced, this should lead to a discussion as to the best method of doing those works, my object in writing to you will be fully attained. lam not an engineer, as you know, but there is one fact which I cannothelp feeling surprised should be ignored by our Engineer, which is that in any part of the river where any perpendicular obstruction to the current is offered it has a natural tendency to deepen; in proof of which I need only call your attention to the first outcrop of the bedrock, on the river bank immediately below the Snag Ealls, where the first deep hole naturally formed exists in the river; and in every other instance where anypermanent perpendicular obstructions exist the result is invariably the same. And I also call your attention to the fact of the continuous deepening going on at the end of all the wharves hitherto erected, until it is found, to the very innocent surprise of the builders, that, while they appear very strong at the top, the piles have been washed out at the bottom ; in fact, the deeper the piles are driven into the bed of the river, the deeper the river becomes, and the more perpendicular the banks, and, of course, the less able to resist the action of the current. I also refer you to Gibson's Quay, Hokitika, where the fact of the piles having been driven to a depth of forty feet was looked upon as a triumph of engineering skill. What are the results ? The works are toppling over into vne stream; tnere is now more than that depth of water alongside.

It is with a desire to prevent the perpetuation of these absurdities that I am now writing, for, should the old system of pile-driving he continued I hope our members will see the necessity of trying to get a vote passed in the estimates to repair them as they are finished. After passing so sweeping a condemnation on the present system, it hardly accords with my notions of fairplay unless a substitute is offered. The suggestion I beg to make is to take advantage of the very favorable circumstance of the natural bar in the river opposite to the upper end of the island—to commence laying crates from the end of the bar at about the fair weather level of the river, and carry them down to the point opposite to where the current strikes the bank, and laid at such an angle as should approximate as nearly as possible to a shelving beach; the result of this would be a fine sheet of water sufficient for all present and prospective trade and perfect security for any vessels in the heaviest freshes. With regard to the permanency of crates properly ballasted, allow me to state that the crates put into the Mokihinui river three years as*o, to turn the river from the Twelve Mile creek, are still standing, and those put into the Shotover, a river discharging a much greater body of water in a fresh and with more violence than that which we have to contend with, are still, after a lapse of seven years, intact. The question of cost I am not prepared to enter into, but, with the material so handy, both in wood and stone, it need not much exceed the present estimate. I hope that this may be the means of drawing attention to the subject and may lead to a full description of the merits of the respective plans from abler heads than the one possessed by yours, &c, Westport. M. J. [The risks referred to by our correspondent have been anticipated by the Engineer. There is to be no perpendicular pile-driving. The effect of a current of five knots on loose stones is, however, a question of considerable import.]