NEW MODE OF CONSTRUCTING BREAKWATERS.

Oamaru Mail, Volume I, Issue 59, 29 June 1876, Page 2

NEW MODE OF CONSTRUCTING BREAKWATERS.

The "New Zealand Times" of a late date gives the following interesting particulars of a new means of constructing breakwaters, invented by Mr. Joseph Dyer. The following statement by Mr. Dyer gives so clear a description of the invention that the proposals of the inventor may be easily comprehended : I, Joseph Dyer, of Wellington, claim to have invented and a new and improved method of constructing seawalls or breakwaters, whereby the force of the waves is so broken and subdued that harbours of refuge may be more cheaply and rapidly constructed than has hitherto been the case. I oppose to the advancing wave a wall, not composed of a flat surface, which would offer resistance to its approach, hnt a wall composed of longitudinal cells or tubes, the open ends of which, closely fitted together, front the wave. These are secured to each other and kept in position by being attached to very long screw-piles, which have a vertical section of an acute triangle, so that they oppose no resistance to the attack of the wave. This wall of hollow iron cells, so attached, extends inheightfromtwo orthree feet below low water mark to such height above high water mark as may be found necessary ; the sectional area of these cells to be of such dimensions as may be hereafter described. These cells, so attached together, and of such length as may be found sufficient, extend backwards towards the shore at a given angle of elevation to the horizon. The sides of these cells, which may be of rectangular or hexagonal shape, converge to each other at the shore or rear side of the said seawall, gradually drmiuishing in dimensions until the aperture at the rear is not more than oneeighth of the area of the aperture at the sea front. The interstices between the converging sides of the said iron cells are to be filled up with cement, concrete ; and the superficies of the wall so constructed will, it is claimed, form a pier or jetty that the sea cannot sweep away or pass over, -but which be used as a road or means of access to shipping, sheltered from the sea by such wall or jetty. It is claimed that the front of this wall of - hollow iron cells, the sides of which are of the thinnest structure compatible with the requisite strength, will oftertheleastpossibleobstruc-

„tion to the" force of the advancing w are as the open mouths of the cells will face the prevailing direction of the current of wave and wind to be opposed in eact specific case. It is claimed 'further, thai the wave in rushing with extreme violence into these partially closed and graduallj rising cells wall have its coherence so de. stroyed and cut up that it will encountg the graduated and elastic obstruction 4 the atmosphere contained in each of tliea. But the rear of the cells being partially open, the air will be expelled with or less force, and thus the vast dynamical force of the water will be employed in com. pressing and expelling the air some thousands of self-acting pneumatj. breaks, and will not avail to disturb % surface of a harbour so protected. It j, claimed that this process will be far cheapg and more rapidly constructed than soty walls of concrete or a wall of masses (j stone deposited in the usual form of| breakwater. It will also be apparent % immediately on the retreat of the wave tin superincumbent air will rush into tin orifices from which it has so forcibly beej expelled, and thus the structure willagaj constitute an elastic atmospheric irf against which waves may dash in vain. In answer to Mr. Stafford,

Mr. Johnson, engineer, said he pledged his professional reputation on the opinio that the scheme was practicable on am coast, except where there was a rocb bottom and the piles could, not be driven The general opinion seemed to be itit the design appeared capable of being v cat ried into effect, and that if it could It carried into effect, the invention would 1* of incalculable benefit, seeing that it isjj. tiniated such a breakwater as that p» posed could be constructed at half thecal of, and in about one-twentieth the tilt occupied in, the construction of ordinal] breakwaters. Mr. Dyer was xuged to ami a trial made in some of the bays in tin Wellington harbour.