. The Canadian journal ; a repertory of industry, science, and art ; and a record of the proceedings of the Canadian Institute. SOUTH WALES KAILWAY. [1852. method of crossing wide spans. Tlie present -w-ork of Mr. Brunei's is another mode," and shows, as might have been exjjected, his peculiarly oris;inal and bold conception, accompanied by extraor- dinary economy, by arranging his materials m the form of a large suspended truss, and attaching the roadway to suspension chains kept in a state of rigidity by vertical trusses or struts inserted between the chains, and a circular wrought-iron
. The Canadian journal ; a repertory of industry, science, and art ; and a record of the proceedings of the Canadian Institute. SOUTH WALES KAILWAY. [1852. method of crossing wide spans. Tlie present -w-ork of Mr. Brunei's is another mode," and shows, as might have been exjjected, his peculiarly oris;inal and bold conception, accompanied by extraor- dinary economy, by arranging his materials m the form of a large suspended truss, and attaching the roadway to suspension chains kept in a state of rigidity by vertical trusses or struts inserted between the chains, and a circular wrought-iron tube, spanning the river, 309 feet in length. The bridge is 600 feet long: there are thi-ee spans over the laud of 100 feet each, which are supported upon cast-iron cyUn- der-s 6 feet in diameter and Ij inch thick. These cylindere were sunk to an average depth of 48 feet, through numerous beds of clay, quicksand, marl, &c., to the solid limestone rock, which was found to dip at an angle of 45 degrees; it had, therefore, to be carefully levelled hoiizontally, and the cylindere bedded level. These cylinders were sunk by excavating within them, and press- ing them down by heavyweights; in doing which very great difficulties were overcome—immense volumes of fresh water were tapjjed, requu-ing a 30 horse engine to pump them out. The quantity very much increased during high water, which lises 44 feet, and in many of the cyhnders work had to be suspended until the tide receded. Although the Wye is a tidal river, and there- fore salt, no salt water was found in these sinkings. Again, dangers arose from sudden and extensive irruptions of soft river silt, "often bursting in with such rapidity that the men had hardly time to escape. Some of the strata were found covered with immense conglomerate boulders, indicating a former river bed. These having been overcome, the cyhndei-s were filled with con- crete, composed of Portland cement, sand and gravel, which set in a few days as
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