E.— 2

15

Before entering upon a consideration of the subject here, I think it well to point out that the gravity of the interests involved, as bearing upon the well-being of Timaru and the surrounding districts, demands that the most searching inquiry should be instituted into the prospects of success or otherwise of the proposed works, before the Board commit themselves to the large expenditure which will be requisite for their construction. Endue haste in precipitating matters in either direction would probably result in disappointment hereafter. Mr. Carruthers considers that my plan is the only one which offers the least chance of success ; but that, having regard to the travel of the shingle along the coast, he does not think, if carried out, it would prove successful, as he apprehends that, after a time, the proposed harbour would be blocked by shingle. He also says that I did not appear to have been informed that heavy seas from the eastward without wind are by no means uncommon at Timaru; and that, as the easterly swell would drive the shingle northward, and a large part of the beach would be sheltered by the breakwater from such a swell, the shingle could not pass along the bank of still water, but would accumulate between the breakwater and the beach. The question of the shingle-travel along the coast has a vital bearing upon the permanent utility and success of the proposed works, and was very fully considered by me before the design was laid down. I explained in my report of 10th August, 1875, the principles which guided me in forming the design, and the reasons which induced me to consider that the suggested works would not interfere with the passage of the shingle along the coast, otherwise than possibly to cause a slight accretion at* first in the bight of Caroline Bay, which would cease as the shore-line was brought more under the direct action of the south-east seas. Two points of great importance as bearing upon the effect of the works on the travel of the shingle must be kept well in view : first, the specially-favourable circumstance that, whereas very large quantities of shingle are incessantly travelling northwards in front of Timaru, the shingle-bank there is narrow in itself, and does not extend below low-water mark. The shingle, therefore, would still be readily acted upon by the sea, more especially in south-east winds, provided no great amount of shelter be afforded to the beach itself. The second point is also a favourable feature in the case: I refer to the fact that, as the south shore of Caroline Bay is almost east and west, whilst the general trend of the coast-line is north and south, it follows that with a given force of wave on the beach the shingle would travel more readily along the south shore of Caroline Bay (see annexed plan) than along the sea frontage on either side of it; and for this reason I determined upon starting the work from the south-east point of the bay, so that any slight obstruction to the waves which might be caused by the piles of the viaduct would be compensated for by the more favourable angle at which the waves would act upon the shingle. As a proof that the shingle travels more rapidly along the south shore of Caroline Bay than at any other part of the coast adjacent to it, I may mention that the belt of shingle is narrower there than elsewhere within the limits of the survey. It is admitted that the seas which mainly act in propelling the shingle travel in a south-east direction, and as the outer arm of the proposed breakwater pier from A to B (report drawing No. 2) is " endon " to the line of seas in that direction, it follows that the work from A to B, whilst it would afford no •shelter during south-east gales, would not affect the northward passage of the shingle. 1 propose to carry the sheltering arm from B shoreward in the direction of ~D only to such an extent as experience may show to be perfectly feasible without materially affecting the action of the waves upon the belt of shingle lying between the high- and low-water marks. Now, the measure of the shelter which these works would afford to the beach would depend upon the distance of the solid structures from the coastline—in other words, if there is a doubt as to the works permitting of the unobstructed passage of the shingle, that doubt, it appears to me, may be removed by increasing the length of the viaduct, and placing the solid works further from the shore. The accompanying trace, marked No. 1, shows the coast-line at Timaru, the direction of the rollers, as observed by the late Mr. Balfour and by Mr. Eliot, and the outlines of the proposed works. I have indicated upon this trace, by means of arrows, what would be the effect of the works upon the easterly swell, to which Mr. Carruthers has referred in his evidence. It will bo seen that with a length of viaduct of 900 feet, as recommended in my report, the sea might be expected to wheel around in the manner shown, so as to fall upon the beach and act upon the shingle throughout the length of the coast to almost as great an extent as is the case at present under similar conditions of sea—in fact, I have been from the first of opinion, and a reconsideration of the case since the receipt of Mr. Carruthors's evidence has only tended to confirm the view, that the proposed works will have but little effect upon the wave-stroke at the beach-line, and that any slight shelter which might be afforded to the shingle upon the beach would be compensated for by the more favourable angle of impact of the waves along that portion of the coast, which may be spoken of as being to the leeward of the works. Mr. Carruthers having a doubt, as to the sufficiency of my estimate, I have thought it desirable to enclose herewith a tracing, marked No. 2, showing a cross-section of the breakwater pier, from which the quantities of work to be executed were ascertained. I also enclose a statement of the principal rates upon which the estimate was based. Of course the details of the mode of construction provided for are open to modification in working out the complete and final set of drawings from which the worka would be executed. The line of action which I have to suggest for your consideration is,— 1. To forward this letter, with its enclosure (or a copy), to Mr. Carruthers for any comments which he may have to make thereon. 2. Should Mr. Carruthers's opinion still remain adverse to the success of the works, then I would suggest that the opinion of another engineer—say, Sir John Hawkshaw—should be solicited. If the Harbour Board are willing to adopt this course, should the necessity arise for doing so, I shall be prepared to hand over to Sir John Hawkshaw, or such other engineer as they may depute, the whole of the information which I have here, leaving the said engineer to draw his own conclusions therefrom, and report accordingly. 3. In the event of the further reasons and arguments which I have adduced in support of the