AN ENGINEERING TRIUMPH

Ashburton Guardian, Volume VII, Issue 2245, 5 October 1889, Page 2

AN ENGINEERING TRIUMPH

Peace says the poet has victories as f among as those which are achieved by the sword, and one of the most remarkable of these is that which has crowned the engineering skill of Sir John Fowler and Mr Baker at the Firth of Forth. The cable advised us a day or two ago that the great bridge over the Firth was completed, a fact the fall significance of which probably few readers appreciated. For this wonderful structure is the most marvellous bridge ever built. It crosses the Firth at Queensferry, near Edinburgh, extending over that arm of the sea m two clear spans of 1710 ft each. These spans consist of cantilevers projecting from steel piers to a distance of 680 feet, each pair supporting girders of 350 feet m length, thus making together a dear span of only 50 feet less than one* third of a mile. The piers, which are made of twelve gigantic steel tube% resting on a granite foundation, tower up to a height of 350 feet above high water level, and the railroad is carried across the Firth at a level of 150 feet above the water. What these dimensions mean will be more readily appreciated when we state that the length of each span is equal to the space between the Union Bank oorner and the bardoor of Henry's Commercial Hotel, the height of the roadway above the Bea nearly thrice that of Friedlanders' new grain store, and. the height of the piers more than six times that of this— the highest building m Ashburton, Writing of this remarkable work an exchange says : — " There will be a clear waterway a third of a mile wide between each pair of piers, and vessels whose masts are less than 150 feet m height can pass under the railway line. One specially noteworthy feature about this in-all-! respects-wonderful bridge is that the cantilevers— each pair of which resembleß a vast arch with a gap of BQQ feet cut out m the middle— have been built steadily out from the piers without any even temporary support from below. Ordinarily, while bridges are m course of erection they are prqpped up from beneath by a temporary wooden frame work (op 'centering ') which is removed oi} completion of the arch, Not so the cantilevers of the Forth Bridge. These mighty segments of steel arches have been steadily built out into the air— into empty Bpace 'just ' (to quote one writer) las » barber sticks out his pole from his door/ Day by day fresh sections have been added on, the workmen, perched on any convenient projection, performing their dutieß at a giddy height abovo the flowing watere. There was no scaffolding. Steam cranes were run on tramways out to the end of the finished portion of the cantilevers and then the steel plates to be next riveted on were hauled up from punts floating m the OBtuary below. It may be added that the work has been oarrled out with surprisingly few aooidents or fatalities. This foot reflects additional credit on the engineers, and on the contractors, Messrs Tailored, Arrol and Co. It may perhaps be asked with some reason ; — What was the inducement to undertake so vast, unprecedented, and costly a work ? The reply is simpleRailway competition. Hitherto the West Coast lines (the London and North Western and the Caledonian) have enjoyed greatly superior advantages m respect of the traffic between England and that part of Scotland lying north of Edinburgh. They run past Glasgow by a short pqt which takes them direct to Larbert and Stirling, whereas the East Coast associated lj nes £tb,e Great Northern, North Eastern, and North British) have to make a long divergence from Edinburgh westward along the south bank of the Forth, before they oan resume the northern journay, which is not till they reach Larbert, whither the West Coast lines have arrived by a direct route, and whence both lines proceed northward to Perth, Dundee, Aberdeen, and Inverness. Tb,e pew route via the Forth Bridge (also crossing the new Tay Brfdge) will give the East Coast the advantage m their turn, and the battle henceforth will be to the swift. The undertaking is onp m which every British subject must fpel a thrill of patriotic pride as the most splendid achievement yet accomplished by engineering spienpeand British pluck,"