Sir William Arrol (1839–1913) was a Scottish civil engineer, bridge builder, and Liberal Party politician.
1839 The son of a spinner, he was born in Houston, Renfrewshire, and started work in a cotton mill at only 9 years of age. He started training as a blacksmith by age 13, and went on to learn mechanics and hydraulics at night school.
In 1863 he joined a company of bridge manufacturers in Glasgow.
By 1872 he had established his own business, the Dalmarnock Iron Works, in the east end of the city.
In the late 1870s he went on to found William Arrol and Co, a leading international civil engineering business.
In 1878, he secured the contract for the Caledonian Railway Bridge over the Clyde, and in 1882 he was awarded the reconstruction contract for the Tay Rail Bridge, which had collapsed in 1879.
His company went on to construct the Forth Bridge which was completed in 1890. At the time, the Tay and Forth bridges were the largest of their type in the world. They were notable not just for their size but also the use of steel in the Forth bridge, and the riveting method developed by Arrol to attach the girders to one another.
Both bridges are known for their high safety factors, a natural result of the under-design of the first Tay bridge by Thomas Bouch, and both bridges have recently (2008) been renovated.
Other notable bridges followed, including: Tower Bridge in London, completed in 1894. Construction started in 1886 and took eight years with five major contractors Sir John Jackson (foundations), Baron Armstrong (hydraulics), William Webster, Sir H.H. Bartlett, and Sir William Arrol & Co.. It employed 432 construction workers.
Arrol also built the Nile Bridge in Egypt and the Hawkesbury Bridge in Australia.
His company, Sir William Arrol & Co., was contracted by Harland and Wolff Shipyard, Belfast, to construct a large Gantry (known as the Arrol Gantry) for the construction of three new super-liners, one of which was the Titanic. Like the ships themselves, the gantry crane was the one of largest built at the time, comparing with transporter bridges in length, height and capability.
Arrol was knighted in 1890, and elected as the Liberal Member of Parliament (MP) for South Ayrshire at the 1895 general election, serving the constituency until 1906. He spent the latter years of his life on his estate at Seafield, near Ayr, where he died in 1913.
His company, Sir William Arrol & Co., continued in business after his death until 1969 when it was acquired by Clarke Chapman.
1913 Obituary 
Sir WILLIAM ARROL, LL.D., was born in the village of Houston, near Paisley, on 13th February 1839, and soon after moved, with his parents, to Johnstone, and subsequently, in 1850, to Paisley.
At an early age he entered Coats' mill, being engaged in the turning-shop or spool department, and it is interesting to mention that he became ultimately one of the directors of this large industrial concern.
At the age of fourteen he was apprenticed to Mr. Thomas Reid, blacksmith, in Paisley, and on its completion he worked in various towns in England and Scotland, by which he gained experience.
In 1863, when only twenty-four years of age, be became foreman in Laidlaw's boiler works in the Bridgeton district of Glasgow.
There he continued for five years, after which be started business on his own account. His capital, formed of his savings, amounted to £85. From this small beginning there has arisen the largest structural steel works in the United Kingdom, occupying about 20 acres and employing at times something like 5,000 men.
Four years after he began business, he built the Dalmarnock Works, which were only on a small scale, about thirty men being employed in the shops. His first important work was the erection, in 1875, of a viaduct over the River Clyde at Bothwell, for the Caledonian Railway Co.
The next important work was the building of the very heavy viaduct across the Clyde at Glasgow, to carry the main line of the Caledonian Railway from the then terminal station south of the river into the existing central station. In this work, begun in 1875, he introduced the multiple drill, so that the plates in the booms could be drilled when superposed, and he also applied for the first time his hydraulic riveter for closing the rivets through these heavy-plated booms. He, however, found great difficulty in getting flexible supply-pipe to withstand an hydraulic pressure of 1,000 lb. per square inch, but by making lengthy experiments he devised a satisfactory pipe.
The most prominent works accomplished by Sir William were the reconstruction of the viaduct over the Firth of Tay, and the building of the great cantilever bridge over the Firth of Forth. Neither Sir William nor his firm had any association with the first Tay Bridge, which was built 1870-8, and partially destroyed by a gale in 1879; but the late Mr. W. H. Barlow, the engineer for the reconstruction of the Tay Bridge, secured his co-operation. The problem was a difficult one, owing not only to the greatness of the work, but also to its exposed position.
Contemporaneously with the reconstruction of the Tay Bridge, he was engaged on the Forth Bridge, which was designed by the late Sir John Fowler, Bart., and the late Sir Benjamin Baker, K.C.B. The work was begun in 1883, and the bridge was opened by the late King Edward VII (then Prince of Wales) in March 1890.
On the occasion of the Summer Meeting of this Institution being held in Edinburgh in August 1887, visits were made to both the Forth and Tay Bridges, and a Paper on "The Machinery employed at the Forth Bridge Works" was read by Sir (then Mr.) William Arrol. The preparation of the machinery alone occupied a year, and the temporary plant cost about £500,000. In the structure itself and its approaches there were used 51,000 tons of steel. The length is 8,295 feet 9.5 inches, and the height is 150 feet above high-water mark. It was in connection with the opening of this bridge that he received the honour of Knighthood, and soon afterwards the University of Glasgow conferred upon him the honorary degree of Doctor of Laws.
Sir William was also engaged in the construction of many of the bridges for railways and roads over the Manchester Ship Canal, and was responsible for the steel work of the Tower Bridge across the Thames. He was among the first to advocate the substitution of steel for timber in the roofs of factory shops. He did not take much part in public life, nor in the work of technical societies.
He became a Member of this Institution in 1887, and served on the Council during 1899-1900. He was also a Fellow of the Royal Society of Edinburgh, and was President of the Institution of Engineers and Shipbuilders in Scotland from 1895-97. For fifteen years-1892 to 1906 he represented South Ayrshire in Parliament, but rarely spoke, although his knowledge of industrial affairs was often utilized in connection with Parliamentary Bills. He was a Deputy Lieutenant for the County of the City of Glasgow, and a Justice of the Peace for the County of Ayr. During the past few years he did not take the same active part in the business of his firm, which was converted into a limited company in 1895, with Sir William as chairman.
His death took place, after several weeks' illness due to an attack of influenza, at his residence at Ayr, on 20th February 1913, at the age of seventy-four.
Sources of Information
-  Wikipedia