Paralysis caused by working under compressed air in sinking the foundations of Londonderry New Bridge / by T.H. Babington and A. Cuthbert.

  • Babington, Thomas H.
Date:
[1863]
Catalogue details

Licence: Public Domain Mark

Credit: Paralysis caused by working under compressed air in sinking the foundations of Londonderry New Bridge / by T.H. Babington and A. Cuthbert. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    It is obvious that to sink these cylinders, and to effect the excavation at such a depth, was a work of no ordinary difficulty. The workmen were to be got into, and out of, the cylinders; the cylinders Avere to be kept empty of Avater; excavations Avere to be carried on; the contents of the cylinder, earth, stones, &c., to be removed; and the concrete for filling to be introduced. All these objects Avere accomplished under the direction of Mr. Hughes, the able and indefatigable resident engineer, by the same means and machinery Avhich he had first successfully used in sinking the foundations of the bridge over the Medway, at Rochester, and aftenvards at ChepstoAv, and at the viaduct at Saltash. A detailed account of the plans adopted at Rochester is to be found in the tenth volume of The Proceedings of the Institution of Civil Engineers for May 13,1851, in a paper by Mr. Hughes, entitled “ The Pneu- matic Method adopted in Constructing the Foundation of the Ncav Bridge on the Medway, at Rochester, By John Hughes, C.E.” We are indebted to, and beg to thank, Mr. Hughes, for kindly placing all his papers at our disposal. The idea carried out was to give each cylinder the character of a diAung bell during the operation of excavating and removing the materials from the interior, and filling in the concrete. Each cylinder AA’-as to be kept free from water, to enable the workmen to excavate until the cylinder Avas sunk to its proper foundation, and all the matters promptly removed from the interior ; and the cylinder should be made to descend vertically. To carry out these objects—that is, to sink the cylinder to its proper foundation—to excavate the interior—to keep the cylinder dry and free from Avater—and to remove the contents and introduce the concrete for filling, Mr. Hughes designed an apparatus as folloAvs;—One of the cylinders—7 feet in diameter, and 9 feet long —Avas fitted with a wrought iron cover, securely bolted to it; through this cover 2 cast iron chambers, called air locks, projected 2|- feet beloAv the top of the cylinder, and 3 feet 9 beloAv the cover— D shaped, with a sectional area of 6 square feet; the top of eacli air lock was provided with a circular opening, 2 feet in diameter, Avith a flap working on a horizontal hinge, which served to close it hermetically when the cylinder was filled Avith compressed air. The communication from the chamber to the inside of the cylinder was through a rectangular opening, 2 ft. by 3 ft. 4 in., on the flat side of the chamber, and had an iron door Avorking on vertical hinges, to close it hermetically when required. The flap Avas analogous in