PRESERVATION OF THE HARBOR.

West Coast Times, Issue 360, 17 November 1866, Page 3

PRESERVATION OF THE HARBOR.

NO. 111. ■ (TO THE EDITOK OF THE WEST COAST TIMES.) Sib — In my last letter, which appeared in your paper of the 14th instant, I endeavored to place before you the approximate boundaries between which I think it imperative that the river should be constrained to run, in order to obviate the anticipated evils which -will doubtless ensue if it is not immediately diverted from its present course. I shall now suggest the means which ought to be adopted for that purpose. Assuming that you have constructed the diagram which I described, I again beg to direct your attention to the line AA, and especially £0 that portion of it between the points c and c, which indicates the course of the crest of the shingle .banks which exist between these points. My object is, to prevent the stream dividing, as at present, at the point d. or at airy point between c and c, and to compel all the water to run between the line AA and the south bank of the river, as far as the shingle bank at c. The cause which impels the stream to take a course towards and along the north bank, between the points d and c, is that the bed of" the stream between the line AA and the north bank is lower than the bed between that line and the south bank of the river. My reason for seeking to prevent the sfcrean" coursing along the north bank, between the points d and c, is, that thereby the power would be destroyed by -which it has raised the Bhingle bank at c, and by which it has, since I commenced these letters, rendered abortive the attempts to restrain its action, by the dams above the cattle reserve, and by the defensive works at Gibson's Quay. In order to effect my purpose of confining the river between the line A A and the south bank, it will be necessary to construct an embankment, commencing at the point c, and extending along the crest of the shingle banks, indicated by line A A, westward to that point where the streams on each side of the shingle bank attain the same level, a point which is a considerable distance to the eastward of point c ; yet I desire that the embankment should ultimately be extended to Gibson's Quay, for reasons which I will hereafter explain. Contempoianeous with the construction of the above embankment, a channel should be cut through the bank at c, between the lines A A and B E, and if the aim of the embankment is attained, as the stream will then impinge directly against this shingle bank, it will soon clear a channel sufficiently capacious for itself, if the cutting should be either too narrow or too shallow. The tendency of the current will then be to block up the old bed of the stream, on both the north and south sides of the new bed near the point ; and should an embankment be found necessary to block up the old bed of " the river, near" the east end of the b"ne 88, it need be but of slight construction, compared with what it would require to be, if it were intended to resist the continuous impact of the river in its present course. Yet, here I do intend to propose an embankment, although for a purpose different from that indicated. I am, &c, James M'Haffie.