The area around Coalbrookdale was one of the foremost iron-producing centers of the world in the eighteenth century. The construction of an iron bridge over the River Severn proved just what could be achieved with the material.
The county of Shropshire, lying in the English East Midlands toward the Welsh border, has always been one of the more rural counties of the country. There is one notable exception, however: the district known today as Telford, in the northeastern part of the county. There, the River Severn,
By converting coal into coke by heating off its sulphur content, Darby was able to smelt iron ore into so-called pig iron. However, because of its high phosphorous content, the iron was brittle and needed reheating with charcoal and further hammering to strengthen it. By 1750, his son, Abraham Darby II, had been able to refine smelting methods to obviate the need for such reworking, and iron production increased rapidly. Other local ironmasters, such as Richard Reynolds and William Reynolds, also Quakers, and John Wilkinson,
By the 1780’s, one-third of the pig iron produced in Britain was being smelted in the district. Abraham Darby III took over the Coalbrookdale works in 1768, after his father’s death. He and other local iron makers developed “cast” and “wrought” iron in the 1770’s and 1780’s, using the steam engines newly developed by James Watt
It was in this context that Thomas Farnolls Pritchard, an architect from the county town of Shrewsbury, proposed to John Wilkinson the building of an iron bridge to span the Severn gorge near Coalbrookdale. Pritchard had started life as a joiner, moved into designing wrought-iron domestic appliances, and had then supervised some bridge building. He went on to design some bridges, using iron and wood, though the designs had never been accepted. A public meeting was called in 1775. There was a legitimate practical need for a bridge to replace the existing ferries, but the real concept behind the bridge was to show practically what a large cast-iron structure could do. The weight-bearing capacity of a single-span iron bridge had yet to be proven.
Pritchard was commissioned to design the bridge. His design was for a single 100-foot span to be sited at the narrowest part of the gorge, using stonework only for piers and abutments, which were to rise above the height of the gorge. Darby, together with Wilkinson, was commissioned to build the bridge to Pritchard’s plan after a separate act of Parliament had been passed in 1776 to set up a commercial and legal basis for it. Differences between the various proprietors led to delays, and construction did not begin until November, 1777. Pritchard died the next month. Work progressed very slowly throughout 1778, and not until the summer of 1779 were the iron ribs in place. Finally, on New Year’s Day, 1781, the bridge opened to traffic.
The original estimate for construction had been £550. In the end, the bridge alone cost £2,737, using 378 tons of iron. The cost of land, abutment, and ironwork brought the final total to about £3,200. A tollhouse was constructed to help pay for the bridge, which is still in use for nonvehicular traffic. The bridge also carried two water pipes under the sidewalk. Gradually a small town, Ironbridge, sprang up around the bridge, which is now the site of a series of museums: The area has been designated a World Heritage Site and includes the eldest Abraham Darby’s house of 1715.
Abraham Darby III used the project to advertise his own skills, commissioning paintings and engravings of the bridge even before its completion. Thomas Jefferson, while a minister to France, purchased one of these engravings, which became a veritable icon of the Industrial Revolution. In 1788, Darby was awarded the gold medal of the Royal Society of Arts for a mahogany model of the bridge. However, despite meticulous bookkeeping, Darby lost a considerable sum of money on the overspend, and the firm’s fortunes declined for a while.
The bridge became a nationwide sensation. It proved iron bridges and other large-scale edifices could be constructed safely. Its success encouraged another local architect, Thomas Telford,
The iron bridge over the River Severn could be considered symbolic of the coal-iron symbiosis foundational to the Industrial Revolution. Interestingly, the district never became urbanized as did most of the other industrial areas of Britain, but it still managed to remain highly productive and innovative throughout the nineteenth century. The fortunes of the Darby family declined under Francis Darby in the first half of the nineteenth century but revived under two of Abraham Darby III’s great-nephews, peaking during the time of the 1851 Great Exhibition.
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Cossons, Neil, and Barrie Trinder. The Iron Bridge: Symbol of the Industrial Revolution. London: Moonraker, 1979. A focused account on the significance of the bridge. -
Muter, Grant. The Buildings of an Industrial Community: Coalbrookdale and Ironbridge. Chichester, Shropshire, England: Phillimore, 1979. An account of the factories, mines, houses, and bridges of the area. -
Ruddock, E. C. Arch Bridges and Their Builders, 1735-1835. New York: Cambridge University Press, 1979. One of the fullest accounts of the technical aspects of the bridge. Includes an index and a bibliography. -
Smith, Stuart. A View from the Bridge. Ironbridge, Shropshire, England: Ironbridge Gorge Museum Trust, 1979. A brief introduction produced by the local museum. -
Trinder, Barrie. The Darbys of Coalbrookdale. 4th ed. Chichester, Shropshire, England: Phillimore, 1993. A full account of this illustrious Quaker family of ironmasters spanning well over a century. -
_______. The History of Shropshire. Chichester, Shropshire, England: Phillimore, 1998. A more general account of the area’s history, with index and bibliography. -
_______. The Industrial Revolution in Shropshire. 3d ed. Chichester, Shropshire, England: Phillimore, 2000. An authoritative study by the leading local historian of the industrial history of the county. Full index and bibliography. -
_______, ed. The Most Extraordinary District in the World. Shropshire, England: VCH Press, 1988. A collection of essays for the general reader. -
Vialls, Christine. Coalbrookdale and the Iron Revolution. New York: Cambridge University Press, 1980. Considers the area the cradle of the first nation to become industrialized.
Newcomen Develops the Steam Engine
Darby Invents Coke-Smelting
Watt Develops a More Effective Steam Engine
Cort Improves Iron Processing
Abraham Darby; Thomas Jefferson; Thomas Newcomen; James Watt; John Wilkinson.