How Thomas Telford's engineering genius changed Scotland

In the Sunday National at the weekend – you can view it online if you didn’t get a printed copy – I concentrated on the Caledonian Canal as it was the 200th anniversary of the official opening of the canal.

I also asserted that the canal was a financial and strategic failure as the advent of steam-powered ships and the fact the UK was no longer at war meant the main reasons for building the canal were overtaken by developments. It was, however, a very successful job creation scheme for the Highlands and it was in the northern half of Scotland that Telford made a huge impact on the land, coast and people.

Even before he planned the Caledonian Canal in the first years of the 19th century, Telford had come back to his native Scotland in 1788, visiting his old haunts and his mother before moving to the far north-west of the country where he carried out a survey for the British Fisheries Society.

It resulted in his construction of Ullapool, turning a hamlet of around 20 houses into a thriving port with a harbour that would be the model for many of his future works.

In that year of 1788, Telford made his name in Shropshire and all around England with two remarkable pieces of work. With the support of his hugely wealthy fellow Scot Sir William Pulteney, he had become surveyor of public works for the county of Shropshire.

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In that capacity, he oversaw the excavation of Uriconium, the “lost” Roman city, now better known as Wroxeter, near Shrewsbury. It was the sensation of the age, not least because Uriconium/Wroxeter turned out to have been the fourth-largest Roman city in Britain.

Telford’s attention to detail was vital for the success of this project but it was his architectural instinct which brought him fame in that year. He had carried out an inspection of the church of St Chad in Shrewsbury and was so alarmed at the state of the building, especially its tower, that he refused to meet the parish leaders, known as the vestry, inside it.

He advised them that the church tower was in imminent danger of collapse but they ignored him and sent for a stonemason. Three days later, with the repairs hardly begun, the entire tower fell in on itself.

Telford recorded in his memoirs: “The very parts I had pointed out were those which gave way and down tumbled the tower, forming a very remarkable ruin, which astonished and surprised the vestry and roused them from their infatuation, though they have not yet recovered from the shock.”

After Ullapool, Telford went back to Shropshire and his survey work, which in turn led him to the design of numerous bridges and roads, but he still found time to write poetry. While in Scotland,he had heard much about Robert Burns and he duly penned verses to the Bard exhorting him to write more in the mould of the Cotter’s Saturday Night.

His original letters were found among Burns’s papers after his death, and excerpts from the Telford verses were printed in the first biography of Burns, written by Dr James Currie and published in 1800.

Like Burns, Telford had been excited by the French Revolution and Thomas Paine’s Rights of Man, though, also like Burns, he had to be discreet about his political leanings because he was in a job paid for by the public purse. Burns, of course, was an exciseman latterly and when he died in 1796, Telford wrote verses showing his irritation at the fact that Burns was under the control of the government’s excise commissioners:

The Muses shall that fatal hour

To Lethe’s streams consign,

Which gave the little slaves of pow’r,

To scoff at worth like thine.

But thy fair fame shall rise and spread,

Thy name be dear to all,

When down to their oblivious bed,

Official insects fall.

Poetry was only ever a distraction for Telford, however, and in the 1790s, he began his great work of building canals, roads and bridges. His first bridge was made of stone and carried the road from Shrewsbury into Wales across the River Severn at Mountford.

Compared to his later work it was small but its three stone arches were greatly admired and proved highly serviceable after it was completed in 1792. The following year saw Telford appointed to design and build what should have been his masterpiece, the Ellesmere Canal. From the outset it was always going to be a monumental project and Telford did not actually put himself forward for the job, perhaps because he knew how all consuming it would be.

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INSTEAD, the leading English civil engineer William Jessop, who had first laid out the route of the new canal, proposed that Telford be put in charge. Telford wrote to a friend: “I was last Monday appointed sole agent, architect, and engineer to the canal which is projected to join the Mersey, the Dee, and the Severn. It is the greatest work, I believe, now in hand in this kingdom, and will not be completed for many years to come.”

He knew the canal would be transformative for much of the west of England and the east of Wales, so he and Jessop wanted only the best for “their” canal. Designing and building it did indeed take years after the Act of Parliament which authorised its construction in 1793, and Telford’s greatest triumphs in the project were two aqueducts which carried the canal over the Ceiriog and Dee valleys in Wales at Chirk and Pontcysyllte, also known as Pont Cysylltau.

Originally it was conceived that the valleys would be traversed by a series of locks on both sides but Telford correctly computed that aqueducts would be cheaper and quicker to build. These both featured iron built into the masonry and their completion shot Telford to national fame.

The latter aqueduct was particularly striking, so much so that Sir Walter Scott, no less, described it as “the most impressive work of art that I have ever seen”.

Telford had used iron extensively in his Ellesmere plan, especially for lock gates and tunnels, but it was for his iron bridges over the Severn that he became famous. This was not the first use of iron in a bridge. French and Italian engineers has tried to use iron for many purposes but could not create enough iron to make it practicable.

However, in the early 18th century, Abraham Darby, a forge master at Coalbrookdale, devised a way of smelting iron with coke, a product obtained from the coal which was abundant in the area. Thomas Paine, who I mentioned above, was actually the first Briton to propose iron bridges. He even produced a sample of a cast-iron bridgework but he had to leave the UK, pursued by the authorities, and his bridge was never built.

DARBY’S grandson, Abraham Darby III – a family obviously a bit short of imagination in the name department – became the first engineer anywhere to build a bridge from cast iron. It opened in 1781 and so famous did it become that the village which grew next to it is called Ironbridge to this day.

It stands in the local authority area of Telford and Wrekin, and perhaps that’s why people think Thomas Telford must have had a hand in building the first iron bridge. He definitely did not but Telford took Darby’s process and improved it, and his work with iron is one of the glories of the Industrial Revolution.

Again, Telford had luck on his side. In 1795 the Severn flooded to unprecedented heights and several bridges over the river in Shropshire were carried away. Thus they unexpectedly needed replaced and Telford was the man to do so.

One of them was at a place called Buildwas, just upstream from the Iron Bridge. Telford decided to build a single arch iron bridge to replace the stone bridge on the site and his own reasonings have survived: “I made the arch 130ft span. The roadway rested on a very flat arch calculated to resist the abutments if disposed to slide inwards as at Coalbrookdale, while the flat arch was itself sustained and strengthened by an outer arched rib on each side of the bridge springing lower than the former and also rising higher thus introducing more of the principle of timber trussing than of masonry. The back of each abutment is in a wedge shape so as to throw off laterally much of the pressure of the earth.”

Here we see the real engineering genius of Telford. He not only solved the problem that had seen the stone bridge wrecked, but anticipated others and calculated how to avoid them. Buildwas Bridge was built at a cost of £6500 between 1795 and 1796, and due to Telford’s scientific approach, it weighed just 180 tons, more than half the weight of Iron Bridge. Buildwas’s Telford arch stood for 110 years and the current steel girder bridge has a piece of the original arch dated ANNO 1796 built into a memorial wall north of the bridge.

With each achievement, Telford’s fame grew and he was greatly in demand for the design and construction of bridges and canals. His Ellesmere Canal project never came fully to fruition, however, as the founders changed the specifications and deleted whole sections of the route that Telford had so carefully planned.

No blame was attached to Telford and such was his speed of work in Shropshire that he designed more than 40 bridges and hundreds of miles of roads over the years. One of his greatest works was the Shrewsbury Canal, begun in 1795, which featured a whole aqueduct constructed of iron – the use of the metal was definitely the way ahead for Telford.

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He came to the attention of the royal family, who admired his works, and, possibly as a result of that connection, in 1800 he was invited to design a new bridge over the River Thames. That his design for a colossal iron bridge never came to fruition was one of the great disappointments of Telford’s life.

London’s loss was Scotland’s gain, however, as the Government contracted Telford to go north in 1802 and carry out a survey which was to change the face of the Highlands.

As we saw with Ullapool in 1788, Telford had worked for the British Fisheries Society, whose governor was his mentor, friend and funder

Sir William Pulteney. On various trips north Telford had compiled huge amounts of data about the lack of infrastructure Scotland, particularly in the North.

The main roads in the Highlands had been created for the use of soldiers after the Jacobite Risings, and had mainly been constructed under the supervision of General Wade. These military or Wade roads were insufficient for the traffic that could open up the north and Telford could also see that bridges were needed to carry better roads.

He also viewed the lack of safe harbours and port facilities as a major drawback. His report to Pulteney found its way to the government and so he found himself surveying many areas of Scotland. What he proposed really did change the face of this country, as you will discover in Back in the Day next week.