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Centuries
of Civil Engineering
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Dempsey, G. Drysdale (d. 1859)
Tubular and other iron girder bridges, particularly describing the
Britannia and Conway tubular bridges.
London, John Weale, 1850.
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The tubes for the Britannia Bridge were raised into
position by hydraulic presses. The presses were mounted at the top of the
towers and connected to the floating tubes by chains of wrought iron
links. The length of throw of the hydraulic presses was exactly the same
as the length of the chain links, so when the press reached the top of its
travel, the tubes were wedged into position, a set of links was removed
from each chain, and the press was reset. As a safety precaution, the
masonry below the tubes was filled in as the tubes were raised, which
proved wise, for on one occasion the hydraulic engine failed and the tube
dropped, but because of the masonry support, it fell only a few inches and
was undamaged.
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