Social England : a record of the progress of the people in religion, laws, learning, arts, industry, commerce, science, literature and manners, from the earliest times to the present day . uction. A goodexample is given by the Charing Cross railway bridge inLondon. The completion of the Forth Bridge in 1889 markeda great advance in the history of girder bridges, as it intro-duced cantilevers for long spans, and was immediately copiedfor bridges in parts of the globe. Imagine two enor-mous steel brackets back to back, forming together a beam orlattice girder 1,700 feet long, tapering e
Social England : a record of the progress of the people in religion, laws, learning, arts, industry, commerce, science, literature and manners, from the earliest times to the present day . uction. A goodexample is given by the Charing Cross railway bridge inLondon. The completion of the Forth Bridge in 1889 markeda great advance in the history of girder bridges, as it intro-duced cantilevers for long spans, and was immediately copiedfor bridges in parts of the globe. Imagine two enor-mous steel brackets back to back, forming together a beam orlattice girder 1,700 feet long, tapering each way from themiddle, where the whole is supported on a substantial is the double cantilever. Its two parts, built up simul-taneouslv, balance each other. Another similar cantilever is at EXGINEERING, 741 a distance of 1,700 feet, and the short space between theirnear ends is bridged by ordinary lattice girders, also builtoutwards from each end. The Forth Bridge is designed witha taper in plan—that is, it is widest at the piers, narrowestat the centre of each large span. This is mainly to with-stand lateral wind pi-essure safely, a lesson learnt from the. TiiK roRTii LEiuta:. sad catastrophe to the original Tay Bridge, overthrown by astorm in December, 1879 (p. 877). The operations of building the piers in deep water wereunique at the time, and offer the best example of the directionof development of this part of the subject. Hollow wrought-iron caissons, or water-tight cjdinders, 70 feet in diameter,were sunk to the rock-bed 72 feet below the water-level. Therock was cut away to receive each caisson, by operations carriedon in a chamber at its base, supplied with compressed air at33 lbs. per square inch to resist the encroachment of the the bed was of mud, the weight of the caisson carriedthrough to the stiff boulder-clay below. In each case the caissonand mining-chamber were tilled with concrete, so that, whenset, each caisson constitu
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Keywords: ., bookcentury1900, bookdecade1900, bookpublishernewyo, bookyear1901
