Before the Iron Bridge

The Gorge was created after the last ice age, 15,000 years ago when a huge lake east of the Welsh mounts carved a deep chasm through layers of coal, iron ore, clay and limestone. With this rich supply of raw materials and easy transport links from the River Severn to the Bristol Channel, this Gorge became one of the most dynamic places in the world during the Industrial Revolution. Many generations exploited the natural resources in the area before the Darby family settled here; iron was made in the Gorge from the time of Henry VIII. It was not until 1709, when the Quaker Ironmaster Abraham Darby I began fuelling his iron-making furnace using coke instead of charcoal, that cast iron became cheap and plentiful.

Making iron cheaply, expansion and exploitation of this new material was paramount to those working in the Gorge and in the 1750s there were six ferry crossings in the Gorge which moved people and materials from one side of the river to the other to aid production. Industry was, however, always at the mercy of the river which sometimes ran too shallow in the summer, and too high and fast in the winter. A new bridge was inevitable and it was Abraham Darby III who seized upon the opportunity for both improvement and expansion, and the plans were laid for the building of the Iron Bridge which stands to this day.

Building the Iron Bridge

The original design of the Iron Bridge was by Thomas Farnolls Pritchard, an architect from Shrewsbury who usually specialised in the restoration of grand houses and had previously only designed bridges to be constructed out of stone or timber; a construction in iron was a completely new innovation. With this in mind he contacted the local Ironmaster, John Wilkinson(who was known as ‘Iron Mad’ Wilkinson due to his obsession of making objects from iron) and sent him designs of a cast iron bridge. A group of local businessmen, including John Wilkinson, approached Abraham Darby III with the plans. Wilkinson went on to make one of the largest contributions to the building of this historic bridge, though he later sold his shares to Abraham Darby III who, with the early death of Thomas Pritchard, went on to see the project through, having made by far the largest contribution to its cost.

384 tonnes of iron would have been needed to building the Bridge, which would have taken three months continuous production in one of Darby’s furnaces. Remarkably, where the iron members for the Bridge were cast is not known for certain, but it is generally thought that it was cast at Darby’s furnace (1.6 miles away from the Bridge’s location), but as, at that time, the whole Gorge was called Coalbrookdale and only later became Ironbridge, they could have been cast at Horsehay (about 3miles away) or Bedlam Furnace which was only 500 yards downstream from the site and on the riverside. In 1801 one reverend gentleman learned that iron for the Iron Bridge had been "cast into the proper pieces in open sand upon the spot". As the members were so large and heavy, a closer location is favoured as it would have been extremely difficult to transport large loads over unmade surfaces by horsepower alone. Whatever the case it must have been a tremendous feat to cast, transport and raise these enormous structures.

There is only one known image of the Bridge under construction, a painting by a Swedish artist Elias Martin. It shows a simple scaffold frame in use, with the ironwork virtually free-standing. When the Bridge was originally built in 1779, it was erected with the abutments in the initial stages. The structure was assembled with the use of many tried and tested ‘timber’ jointing techniques, such as dovetails, wedges and mortise & tennons which may account for the Bridge’s resistance to geological pressure because of the "give" in such joints. Many people have speculated and theorised over the years as to how the Bridge was actually constructed. In 2000 BBC Timewatch came to the Museum and erected a half-scale model of the Iron Bridge over the canal which runs through Blists Hill Victorian Town. They used the same methods as indicated in Elias Martin’s painting and successfully installed three ribs. During this exercise, new discoveries were made which gave a wider picture as to how the engineers of 1779 would have managed such a construction. The final cost of building the Bridge was £6,000, but if Abraham Darby had wanted to build such a bridge today, he would have to raise in the region of £1.5 million.

The Iron Bridge Tollhouse

There was a long delay before the Bridge was opened to traffic, which took place on New Year’s Day 1781. It is thought probable that the Tollhouse was erected before the bridge was opened to traffic, but none appears on early illustrations of the Bridge. It is known that during 1780 Darby was directing the construction of the abutments, which would suggest that the Tollhouse may have been erected at this time. It is known that the Tollhouse was enlarged in 1835 which is how it stands today. An Act of Parliament for the Iron Bridge dated 1776 includes in its text the toll prices which never changed and to which Royalty was not exempt. These can be seen today on the outside of the Tollhouse.

Promotion for the Iron Bridge project

The picture "The Cast Iron Bridge near Coalbrookdale" was painted by William Williams in 1780, before the Iron Bridge was completed in order to promote what was an enormous feat of engineering. It was the equivalent of modern-day drawings depicting what the end product of project is expected to look like. The painting was produced from an engineering drawing, a copy of which was given free to every purchaser of the engraving of the Iron Bridge by William Ellis after Michael Angelo Rooker. Features added to the painting, such as pleasure boats, coracles and trows emphasised the industriousness on this stretch of the River Severn. The Gorge at that time was renowned for having more furnaces and forges along two miles of the riverbank than anywhere else in the world, and smog and industrial disorder would have been far nearer the truth than the image created by this painting.

The Iron Bridge has become a symbol all over the world and reinforces the belief that Ironbridge is indeed the "Birthplace of Industry".