The Press. TUESDAY, APRIL 9, 1867.

Press, Volume XI, Issue 1379, 9 April 1867, Page 2

The Press. TUESDAY, APRIL 9, 1867.

Mb. Balfoub's report on the harbor works at Lyttelton is a document which fully substantiates the character he bears as a sound practical engineer; but, in addition, it is a document full of good taste and good feeling. He evidently disapproves of the design of the sea-wall, for he distinctly says that were the work to be done again he " should certainly recommend a different design and would probably dispense with a timber facing entirely in I the first instance." At the same time no small part of the report is occupied by considerations of an apologetic char- | acter, excusing or accounting for the I plan of the Provincial Engineer. Well, we do not think the worse of Mr. Balfour for the spirit in which he writes, especially as he goes on to offer practical suggestions of the greatest importance as to future operations. In dealing with a site whose materials are shown to be so treacherous as those of the bed of Lyttelton harbor, he points out that the future slipping of the materials thrown in to form the site of the Eailway-station, must be expected. In point of fact the site of this piece of made ground consists of a bed of rock slopiug outwards towards the harbor, probably at a very steep incline, for at a little distance from the shore the rock has sunk below the \ reach of the borings. Upon this steep incline lies a bed of fine soft mud, which is mere slush at the surface, and is consolidated into a stiff clay at a certain depth. It is easy to see that no site could be found more treacherous to any superstructure raised upon it. The earth and stone thrown in must tend to slide down the incline into the harbor ; and nothing but a very strong breastwork — a much stronger one than that adopted—could prevent its doing so. Mr. Balfour seems to think that he would have preferred filling up the ground first

and letting it slip as far as it would, until it came to its natural slope, before erecting the timber work in front. We should only differ with him in one point, and that is, in building any timber work at all. We cannot conceive of what use it is to be. It will certainly be of no use for discharging cargoes except from very small craft, the position being dangerous and the depth of water inconsiderable. The rubble thrown out of the tunnel has come to a natural slope, and, as we hear, stands tolerably well. Of course it is a low slope, probably not more than 1 in 6, but it has proved sufficient to support the earth filling behind it. We never could understand why the site for the station was not simply filled in and a facing of stone rubble added towards the sea, Mr. Balfour gives two practical and important suggestions. He recommends that the filling in should now be conducted from the shore, so as not to touch the sea-wall, and so that it will have room to slip somewhat without bringing any additional pressure.on the outer works ; and he also recommends that nothing more shall be done to improve the face of the sea-wall until the whole filling is complete and has settled down as far as it will. The latter is obviously a most important suggestion, for it will save the province the expense of putting up further works only again to see them pushed into the sea by the unstable mass behind. When the earth filling has finally done its worst and settled down as far as it will go, there will then be ample security that any additional row of piles driven outside so as to restore the even face of the sea-wall will stand. Mr. Balfour goes on to suggest short jetties run out from the sea-wall so as at once to act as buttresses, and to afford accommodation for shipping. We can only say " sufficient unto the day is the evil thereof." We deprecate any more money being spent on small jetties in shallow water until we have at least one jetty for large ships. If the other recommendations in Mr. Balfour's report are attended to, we may fairly expect the water to stand without these jettieuli. The second question with which Mr. Balfour deals is the breakwater at Officer's point; and here, too, much as he tries to treat his professional friend with tenderness, he points out the danger of using too small rubble in a work of this description. He does not, however, tell us what has been the character of the materials hitherto used. Reports are current that not only small chips of rock, but in large quantities. Mr. Balfour evidently holds that little but large rocks should be used, and no more rubble " than sufficient to fill up the crevices between the larger blocks." We want to'know whether that is the way in which the breakwater has been hitherto built ? And we should like to see some assurance given by the Government that Mr. Balfour's suggestion shall be honestly carried out for the future. It is many months ago since we called attention to this subject. Now that the leading man in the profession in this colony, since Mr. Doyne's departure, has spoken, perhaps something will come of it. But Mr. Balfour goes on to point out how a wharf may be constructed at Officer's point, and connected at once with Christchurch, at a comparatively small cost, and commanding a very fair depth of water. We can only express our gratification that a plan so frequently and earnestly recommended in these columns should have at last received such high sanction. We never thought there could be two rational opinions as to the plan, but we are now in great hope that the thing may be done. We are not, however, disposed entirely to acquiesce in Mr. Balfour's opinion as to the silting up of a wharf at Officer's point. It must have escaped that gentleman's attention, that the water around the reef at Officer's point was always slightly deeper than that further out in the harbor. And the*" reason is obvious. The ebb tide setting in to Erskine bay sweeps round the Lyttelton beach and creates a strong run off the northern reef, which evidently deepens the water. Now as the breakwater is carried out, one of two things will happen; either the stream of the ebb-tide will set out of the bay towards the end of the mole, leaving an eddy inside on the northern shore, or it will sweep round the shore and along the inner face of the breakwater. In the former case it will gradually silt up the bight caused by the breakwater; in the latter it will tend to plough out a deeper channel along its inner side. Looking at the angle at which the breakwater is being built to the shore and to the set of the ebb tide, we are inclined to think that the latter will be the case. If the whole bay be walled up, according to the design of the English Commissioners, no doubt the dock so formed will silt up, unless kept clear by artificial means; but so long as

the ebb tide sets into the bay, the lee side of the bay will probably be deeper than elsevrtiere, and at least as deep as at present; and 19 or 20 feet of water at low springs may be relied on for a considerable length of the wharf. If however a Tof solid material should be run out from the mole towards the town, the silting up would be rapid ; any such work should be open. We would again point out that for something like £20,000, speaking loosely, two chips of a thousand tons might, within a few months, be discharging their cargoes on to the railway in immediate connection with Christchurch ; and that by no other plan yet proposed could the same result be brought about for much less than tenfold that sum. Mr. Dobson's estimate for a railway pier to reach into only 13 feet of water was £100,000. Let us then hope that Mr Balfour's plan will be acted on, and that at once.