Sir William Arrol (1839-1913) – The Engineer

A titan of engineering and construction, William Arrol established his company in the early 1870s, when Glasgow was developing as an industrial city and the revolutionary Siemens Martin process was enabling the mass production of cheap steel. Arrol made his name with the construction of the Forth Bridge (1890), and is also known for the second Tay Bridge (1887), Tower Bridge in London and elsewhere.

Now a UNESCO site, the Forth Railway Bridge is recognised as a ‘masterpiece of creative genius because of its distinctive industrial aesthetic’ and as an extraordinary milestone in the evolution of bridge design and construction. However, the construction of the bridge was not without its difficulties. William Arrol won the contract for the Bridge Thomas Bouch designed in 1878, but due to the collapse of Bouch’s Tay Bridge in 1879 the project was put on hold. It wasn’t until 1882 when Parliament authorised the construction of a new Forth Railway Bridge design by Benjamin Baker and Sir John Fowler, that Arrol was contracted again to begin work. Concerned with re-establishing the public’s confidence in large scale engineering works, it has been suggested that this led to the Bridge being ‘over-engineered’, however it is perhaps due to this care that it still stands in use today, 128 years after its completion.

A great engineering feat spanning the tidal estuary of the River Forth, the Forth Bridge has become an iconic part of the landscape. Indeed, its design and size were so unusual at the time, many found it either beautiful or ugly.

“The bridge is a style unto itself: the simple directness of purpose with which it does its work is splendid and invests your vast monument with a kind of beauty of its own, differing though it certainly does from all the beautiful things I have ever seen” (Alfred Waterhouse)

It was the concern with safety and the difficulties of construction in the fast flowing river that led Arrol to innovations in technology and methods of working. These innovations included the creation of complex drilling and riveting machines, and Giant Cantilever or Titan cranes capable of lifting 150 tonnes or more.

Although there is some dispute as to whether Arrol is the only inventor of riveting machinery, he certainly revolutionised the process by applying hydraulic pressure and designing machinery that was easily transported in every direction with movable tubes. This allowed workers to place approximately 7 rivets a minute. To overcome the problem of building in the river, Arrol used a system of caissons. Watertight structures, once sunk in the water, the water inside the caissons was pumped out and replaced with compressed air and airlocks installed. This allowed workers to go below the surface in submarine air chambers to excavate the boulder-like clay beneath and sink the caisson further. Once complete the working chambers were filled with concrete and masonry piers built above.

These inventions and the development of engineering workshops that provided clear working spaces with the capacity for overhead cranes, were extensively adopted by heavy engineering such as bridge building and shipbuilding.

From 1 August to 1 September a small sample of our records from our unique Caledonian Railway Company and British Rail Archives will be on display in the General Register House’s Matheson Dome in our Fringe Festival exhibition, ‘Famous Scots from the Past’. Featuring some of Scotland’s most remarkable historical characters, a selection of records relating to Sir William Arrol and the Forth Bridge will be on show. Come along and discover more about Arrol and the unique records held in our archives.

Jocelyn Grant, Outreach Archivist

National Records of Scotland

Further Reading

• United National Educational, Scientific and Cultural Organization, The Forth Bridge
• Scottish Engineering Hall of Fame, Sir William Arrol
• Oxford Dictionary of National Biography, Arrol, Sir William
• National Records of Scotland, Sir William Arrol (1839-1913)
• Evelyn George Carey Forth Bridge, Michael Gray and Angelo Maggi (2009)
• The Forth Bridge: A Picture History, Shelia Mackay (1990)
• Sir William Arrol: A Memoir, Sir Robert Purvis (1913)