Strutt, William: The sky's the limit

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Most people would assume that the skyscrapers which dominate our cities are a modern-day invention. But that’s not the case, as Vivienne Smith reveals.

Charles Bage’s Ditherington Mill, in Shrewsbury, was the world’s first multi-storey iron-framed building. Bage was born in Derby

The iron columns inside Charles Bage's Ditherington Mill, in Shrewsbury. These same features can be viewed by visitors to Belper’s North Mill. Bage was born in Derby

The plan and section of Strutt’s Derby cotton mill, built in 1792

The plan and section of Charles Bage’s Ditherington Mill. Note the similarities to Strutt’s design

The framework structure of columns and beams of the modern skyscraper

Most people think America is the birthplace of the skycraper. But this is not strictly true. Certainly, the first modern building of this type was erected in the United States, back in the 1880s.

Yet, this revolution in structural engineering actually had its origins in Derby almost 100 years earlier.

The story begins with that celebrated benefactor of the town, William Strutt.

The eldest son of cotton manufacturer, Jedediah Strutt, he was born at Newton Old Hall, near Alfreton, in 1756 and entered the family business at the age of 14.

He soon revealed an inventive streak as an architect, through his involvement in the design and construction of new mills for the company.

The building for which William Strutt is generally known is the Derbyshire Royal Infirmary, the most innovative hospital of its day.

But his most significant achievement in this field was actually the construction of the world’s first fireproof building.

Remarkable in its own right, the structure also proved to be the prototype of the skyscraper.

At the end of the 18th century, the greatest threat to textile mills was destruction by fire, especially for those working with a material as combustible as cotton.

Indeed, all round the country there had been an alarming increase in the number of such fires.

It was a situation that simply could not go on.

Strutt was one of those determined to find a solution to the problem.

So, when his father decided to build a new cotton mill in Derby in 1792, the 36-year-old undertook the design of it himself, intent on creating a fireproof structure.

The ideas he came up with were dramatically different to traditional construction techniques. In fact, they constituted a major turning point in the history of structural engineering.

Erected just south-east of the Market Place, the Derby mill was 115ft long, 30ft wide and six storeys high.

It was not its size, but the method of construction that was revolutionary.

The floor was made of brick arches sprung from heavy timber beams which were supported by two rows of cast-iron columns.

As an additional fireproofing measure, the timbers were coated with plaster on the underside.

Completed in 1793, Strutt’s mill won wide acclaim as the first fireproof building the world had ever seen.

Although no one could possibly have known it then, this pioneering structure composed of columns and beams was also a forerunner of the skyscraper.

Strutt made further improvements to his fireproof construction in the building work that followed.

His four-storey warehouse at Milford and the West Mill at Belper (completed in 1795) were both of a similar design.

However, it was his good friend Charles Bage who took this prototype construction to the next stage of development.

Born in 1751, almost certainly in Derby, Charles was the eldest son of local man Robert Bage.

His father established a paper mill at Elford, near Tamworth, before later finding fame as a novelist.

Charles, however, set himself up as a wine merchant, following a move to Shrewsbury in his late 20s. But before long, engineering had become his new passion.

At the time, Shropshire was teeming with exciting industrial activities, especially those involving the use of iron.

Not far from Shrewsbury, the famous Iron Bridge had recently been erected using castings made at the nearby ironworks of Coalbrookdale.

Bage even made the acquaintance of Thomas Telford, who was the county surveyor in those days.

So, it was hardly surprising that, when asked to design a flax mill on the outskirts of Shrewsbury in 1795, he gave serious thought to using iron.

The work was undertaken on behalf of flax spinner John Marshall and textile merchants Thomas and Benjamin Benyon.

And Strutt also played a vital role in the project.

Inspired by his fireproof mill, Bage corresponded with his friend to ask for advice and discuss his ideas.

In a letter to Strutt in September 1796, for instance, he summarised the earliest known practical theory for the strength of cast-iron columns.

He ended up modelling his building on the Derby and Belper mills, but with one significant difference.

To make the structure more fire resistant, he opted to use cast-iron, not only for the columns, but also for the beams.

This was a bold decision by the Derby man and one which established him as a true pioneer in structural engineering, for Ditherington Mill, in Shrewsbury, became the world’s first multi-storey building to be built around an iron frame.

Completed in 1797, the structure was 177ft long, 40ft wide and five storeys high. It still stands in the 21st century, a remarkable testimony to the man who designed it.

At first, concerns were raised over the suitability of cast-iron for beams. After all, this was the cutting edge of technology at the time.

But, before long, engineers all over the country had adopted the technique for making fire-resistant buildings.

Bage himself won the reputation for being an expert on iron framing.

In 1801, he was even invited to give evidence before the Parliamentary Select Committee regarding Thomas Telford’s proposal for a single-arch iron bridge across the Thames.

Meanwhile, he continued to investigate the properties of cast-iron.

In a letter to Strutt in August 1803, Bage announced a theory he had developed from experiments on the strength of flanged beams.

That same year, at the Shrewsbury works of iron master William Hazeldine, he tested out his ideas by conducting the earliest comprehensive loading tests on iron roof frames.

This included possibly the first ever trials carried out on the torsional strength of iron.

This new found knowledge was at once put to use in the building of a Bage and Benyon flax mill in Leeds and another one in Shrewsbury in 1804.

Meanwhile, Strutt himself had not been idle.

Having followed his friend’s work with interest, he was itching to construct a fully iron-framed building for himself.

The opportunity came in January 1803, when Strutt’s North Mill in Belper burnt to the ground. From the ashes of this disastrous fire came a new mill which was similar in dimensions to the Derby one.

But this time it was completely iron-framed. The building still survived. Today, it is used as a visitor centre and museum; its revolutionary iron beams and columns are on display for any who care to look.

Strutt went on to use this method of construction when extending his Milford warehouse in 1806, as well as in the erection in Belper of the Reeling Mill (1808) and the South Mill (1812).

Sadly, along with the Derby mill, these are all now gone.

In each of them, he made improvements to the design of the iron beams.

He succeeded in producing ones that were far more durable and lightweight than Bage’s original efforts.

By the time of Strutt’s death in 1830, his fireproof building design had progressed in leaps and bounds.

As the Derby Mercury recorded in his obituary: “The great improvements made of late years in the formation of castings in iron have given great facilities to this mode of construction, which is now very extensively in use.”

Bage himself had died eight years earlier.

But the building revolution that the two men had started was, quite literally, set to reach new heights, for the Derbyshire and Ditherington mills were the first links in a chain which would eventually result in the modern-day skyscraper.

However, two further developments had to come to fruition before this was possible.

In order for buildings more than six storeys high to be practical, the safety lift had to be invented. In 1852, American Elisha Otis came up with the goods.

The construction of truly tall buildings also needed the creation of a material both stronger and lighter than iron, namely steel.

Briton Henry Bessemer devised the method of converting molten pig iron into steel in the 1850s, but it was another 30 years before structural steel was commercially available.

The first modern steel-framed skyscraper was the 10-storey Home Insurance Company Building, erected in Chicago in 1885.

Although made of steel, not iron, the building’s framework structure of columns and beams was a direct descendant of that conceived by the two Derby men.

Today, the world’s tallest skyscrapers are more than 100 storeys high and, no doubt, in the future will be taller still.

With his multi-storey iron-framed building, Charles Bage created a revolutionary method of construction.

Yet, he might never have done so had William Strutt not made the initial breakthrough with his fireproof Derby Mill.

The technique they pioneered remains the favoured method of construction for really tall buildings the world over to this day.

No question, Derby truly is the birthplace of the skyscraper.