THE OTAGO GRAVING DOCK,

Grey River Argus, Volume VIII, Issue 543, 10 July 1869, Page 2

THE OTAGO GRAVING DOCK,

The importance of this work to the roari* time interests of the colony has been fully recognised for a lone; time past. As far back as the year 18G5 the subject was taken up •with some degree of earnestness by the Pn . vincial Legislature, and at that time it whs ascertained that an aotnal loss of L 25.000 had been sustained through the want of appliances for examining and repairing vessels of heavy tonnage, This calculation was based upon the number of vessels c< ndemued within the preceding few years, which might otherwise have been rendered perfectly seaworthy, besides those that bad been compelled to leave Port Olago for repairs. This fact was elicited by a Select Committe ■ c f the Provincial Council, and in a report which followed, a strong representation whs made that the construction of a dry dock should be proceeded with at once. Upon that recommendation various suggestions for carrying out such an undertaking followed. Th<? one which received the most favorable consideration was that of constructing a stone graving dock on a. portion of land res-rved for harbor improvements at Port Chalmers. The suggestion was all but unanimously adopted by the Council, and an Act entiiled the Otago Dock Trust Ordinance was passed. This Ordinance constituted certain of the principal merchants and shipowners residing in Dunedin and Port Chalmers a Trust, with power to borrow money, and transact other business connected with the scheme. A further object of this Act was to enable the Trust to take advantage of an Act of the Imperial Legislature, authorising the 1". n of L 20.000 by the Home Government, at 4 ( >er cent. Upon inquiry, however, it was ascertained that to secure this assistance a <10. k would have to be constructed sufficient to admit large vessels of Her Majesty's navy ; but as the advantage was not deemed equivalent to the extra outlay, this intention w»s abandoned. The Dock Trast Bill having been assented to by the Governor, some considerable delay took place in the completion of surveys, and it was not until the middle of last year that the final report respecting preliminary arrangements for commencing the work wna submitted by the Trust to his Honor the Superintendent. Within a fjw weeks of the issue of that report, viz., on the 20th July, 18G8, the commencement of the work was formally inaugurated by his Honrr the Superintendent in the presence^ of members of the General and Provincial Legislatures, besides a large concourse of private individuals, Although still far from being complete, it is now sufficiently advanced tj« enable us to form a fair estimate of its general outline. .A* already stated, the site selected forms

a portion of the river frontage reserved in trust to. the Superintendentof the Province for the iaiprovemenijpf th%Harbor of Port Chalmers. It is sltuate-l fiarely 120 yards from the town on the northern side of the ftnaiUand, terminating in what is known us Koputi'i Bay. T»e central line of the dock runs parallel with that of Port Chalmers wharf, a position the value of which is greatly enhanced by its proximity to an excellent stone quarry. At the entrance to the dock, which ia considered by far the most important part of the woi k, the solid rock has been found at a very suitable level- about two feet below the lower courses of the masonry — so that any necessity for expensive foundations has been hereby obviated. The The depth of water in the entrance is Bft. at low water. 14ft. at high water of a spring tide ; but as tbe bottom consists of soft mud, to a depth of Bft. at least, there will be, comparatively speaking, little difficulty in getting a channel dredged out to deep water. The dimensions upon which the dock is constructed are as follows : — On the floor line within the gates, 328 ft .; at the level of the cope, 342 ft .; breadth on the floor line, 41ft. ; and at the level of the cope, 68ft- The depth at the shallowest part of the entrance at high water will be 22ft., with a width of the entrance at tbe gates of 50ft. in the clear. These dimensions will be sufficient for the largest \essel that has yet visited Otago. The coffer dam is constructed on rather an exceptional principle, and is made to combine lightness with strength of structure. The usual plan upon which such dams are constructed is by driving two lines of piles, h'llintr them up between with puddled clay, lv this instance, only one row has been driven in a semicircular form, set close together, each having a smooth side on which battens four inches by two are fixed, each line four inches apart from the other. These battens, being closely knitted together, are to be caulked in between with straw, to a depth of about three feet below the present bottom. This portion of the work is expected to be finished in the course of a few weeks, when the centrifugal pumps manufactured by Messrs Wright and Co., of Melbourne, will be set to work, pumping out the water. This completed, the work of excavation will commence, according to the dimensions stated above. A solid cement concrete foundation will afterwards be laid, on which the stone paving and side walls are to be built. The latter will be backed up with thick walls of concrete, and both are to be carried on at the same time. For the masonry work, it is estimated that 85,000 cubic feet of dressed atone will be reinired. At the present time about a third of that quantity has been prepared, and the men are busy at work, hewing out the remainder. For the concrete, one machine has been fully employed for some time past breaking stone, and another is shortly to be placed upon the ground. The facility afforded by the site hi this respect is an important feature, so far as the progress of the work is concerned. The stoiifs, after being broken up. are sent down a shoot, whirh deposits them quite close to the dock. Indeed, the quarry fmm which the stone is taken ia situated almost directly overhead. The gates are to be made of Swan River mahogany, or " Jarrah," a description of timber which is understood to be proof against tLe inroads of the marine boring worm. The pumps are capable o£ dischari;ing at the rate of thirty-one tons of water ppr minute, which will enable the dock to be pumped dry in about three hour*. The main pump was made by Gwnpe, of London, and the engine by Tennant, of Leith. The contract for the work was taken up by Mr Connor, fo • the sum of L 48,872 5s sd. We have little hesitation in endorsing the opinion generally expressed that* its completion will mark »• new era in the progress of the Province.— Daily Times.