Untitled

Hawke's Bay Times, Volume 6, Issue 317, 23 October 1865, Page 2

l’< ew J nojr JliiixtOE, — There has been just completed. in the yard of the Regent’s Canal Ironworks Company, a remarkable iron bridge, which is the hirgcst yet-constructed on a plan that will probably have a very extended application. The structure in question lias been made to the order of the Indian Government, and is designed to be erected in India. The leading feature of the new principle is that, without the necessity of any subaqueous works, or the erect ion of any intermediate towers or piers, the bHdge can lie built to cross in a single span any river or clmsm up to an extreme width of 500 yards, or 1,300 feet. Thus the river Thames at Hungerfon! could be crossed with a bridge in one span, without the necessity of driving a pile or raising any other erection in the bed of the stream, Th-> bridge just finished for the Indian Government servos to eSciapiify fully the purpose of the inventor and engineer, Mr A, Seley, It is of 75 feet span and

14 feet wide 5 its total weight is 22 tons, including the roadway, and it will support a nominal strain of four tons per sectional inch, but really a much greater weight. Two great cantilevers, or wedgeshaped girders, are built up piece by piece till they are projected from opposite side* of the chasm or river which is to be bridged over, and extended till they approach withiu a distance something less than a third of the whole span. Across tliis space a central girder is thrown, winch, while it completes the continuity of the bridge acts, when fixed in position and rivited down, as the keystone, so to speak. The wedgeshaped girders which project from either side of the stream are at their wide ends embeded and built into massive piers of masonery on the shores. The base of the wedge is fixed by iron tugs, in an upright position ; the central arm of the girder supports the actual roadway of the bridge ; the lower arm stretching to the poin of the girder becomes a bracket support; and the upper ana passing over the summit of the upright end, which makes the thick end of the wedge, is extended backwards as a tedsion bar, and anchored firmly in the earth, thus giving suspensory support to the central arm, which attains a perfect rigidity. Upon the piers the whole strain is thrown. The roadway is constructed of the iron backed plates, invented by Mr Mallett, which have done such good service on Westminster bridge. The strength of the structure is really much in excess of what is actually required, and yet the lightness of the whole is most extraordinary. The weight of the present bridge is only 22 tons—less, in fact, than one girder of a shorter iron bridge that is being constructed beside it. A small ornamental bridge, built on the same principle for a gentlemen’s park a short time since, was 36 feet span, and weighed only 10 cwt. The cost of tbo carriage of this bridge from London to Staplehurst, where it is put up, was lls. For the hill roads in India the bridges constructed on Mr IdeUley’s new system will be the means of solving a great difficulty.— Daily Telegraph.