Bridges presentation
1754, Henry Cort of Southampton (England) built the first rolling mill, making possible the efficient
shaping of bar iron; in 1784 he patented a puddling furnace by means of which the carbon content in
cast iron could be reduced to produce malleable iron. These two milestones of metallurgy realized
the potential of iron as a major building material. Bridges were one of the first structural uses of
iron, preceded only by columns (not yet beams) to support the floors of textile mills.
Figure 7 Dunlaps Creek Bridge (1839), Brownsville,
Pennsylvania (USA), spans 80ft (24m) on five elliptical
ribs of cast iron made of nine 14ft (4m) segments
flanged at the ends and bolted. The triangular bracing
in the spandrels is reminiscent of Telford's iron bridges
in Shropshire (UK), and the tubes resemble the eliptical
arches of the Pont du Carrousel, built over the Seine in
Paris in 1834. Library of Congress
The first successful all-iron bridge in the world was designed by Thomas Farnolls Pritchard, an
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