Stevenson, Robert (1772-1850) (DNB00)

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STEVENSON, ROBERT (1772–1850), civil engineer, born at Glasgow on 8 June 1772, was only child of Alan Stevenson, a West India merchant, who died at St. Christopher on 26 May 1774, when Robert was an infant. The father came of a family whose members were originally settled as cultivators at Nether Carswell in the parish of Neilston, Renfrewshire, and afterwards, in the eighteenth century, engaged in business first as maltsters and later as West India merchants at Glasgow. Jean, Robert Stevenson's mother, was the daughter of David Lillie, a builder in Glasgow. After her husband's death she was for a time in straitened circumstances, and Robert began his education in a charity school. It was intended that he should enter the church, but before he had attained his sixteenth year his mother married Thomas Smith, engineer to the recently (1786) constituted northern lighthouse board, and he entered his stepfather's office. He studied civil engineering at the winter sessions of the Andersonian Institute, Glasgow, and afterwards at the university of Edinburgh. Smith showed his confidence in him by entrusting to him, while still in his teens, the superintendence of the erection of lighthouse buildings, lanterns, and optical apparatus, and the formation of ‘macadam’ roads of access to lighthouse stations. Communication with headquarters was difficult, as the stations were often situated on uninhabited islands or headlands, to which the materials were brought in smacks. In 1796 Smith took him into partnership, and he married Jean, Smith's eldest daughter by a former marriage.

A few years later Stevenson succeeded Smith as engineer to the Scottish lighthouse board, and held the office for about half a century. He practically inaugurated the Scottish lighthouse system, which is still conducted on the lines he initiated. Under his superintendence no fewer than twenty lighthouses were designed and constructed, and many improvements, now in universal use, were due to his ingenuity. He brought the catoptric or reflecting system of lighting to perfection, advocated the adoption of the dioptric or refracting system with its central lamp, and invented the intermittent and flashing lights; for the last invention the king of the Netherlands bestowed on him a gold medal. The most important of his lighthouses was the famous Bell Rock tower, erected on a dangerous reef submerged by every tide to the depth of twelve feet, and lying in the fairway of ships making for the estuaries of the Tay and Forth. Previous attempts made by Captain Brodie to erect beacons upon it had failed. In the storm of 1799 seventy sail were wrecked off the reef, among them the York, 74-gun ship. After a careful survey Stevenson designed and modelled a tower, and reported on 23 Dec. 1800 to his board that the erection of a stone tower on the reef was practicable. Public opinion was sceptical, and when the board applied to parliament in 1803 for powers to carry out the design, the bill after passing the commons was withdrawn owing to difference of opinion regarding the extent of coast over which dues to meet the expense of erection and maintenance should be levied. Before again going to parliament the board, on Stevenson's suggestion, consulted John Rennie [q. v.], who concurred in Stevenson's opinion. Both Stevenson and Rennie gave evidence before a new parliamentary committee, and the act was passed on 21 July 1806. Active operations were begun on the reef in August 1807. Rennie was appointed nominally chief or consulting engineer, to whom Stevenson in any case of difficulty could apply. Rennie, who had no experience of lighthouse construction, suggested various alterations of the design, but to none of them Stevenson gave effect. After five years of arduous labour the lighthouse was in working order. Stevenson described its construction in 1824 in his ‘Account of the Bell Rock Lighthouse.’ The tower, which, as in all Stevenson's lighthouses, is free from architectural adornment, rises to the height of 100 ft.; the diameter at the base is 42 ft., diminishing to 15 ft. at the top. Above the solid, which is 30 ft. in height, is the entrance doorway, the interior being divided into six stories. Smeaton in his Eddystone tower adopted an arched form of floor, rendering it necessary to insert chains embedded in the masonry to counteract the outward thrust; but in the Bell Rock tower, by an ingenious arrangement of the masonry, the stone floors were converted into effective ‘bonds,’ thus tying the walls together, for as the stone floors form part of the walls, outward thrust is prevented. All subsequent rock towers have this form of floor. The cubic contents of the tower are more than double those of the Eddystone, from which it differs in many respects owing to its far more difficult and dangerous site. The tower was protected both externally and internally from lightning stroke, and thirty-five years afterwards, on the advice of Faraday, a somewhat similar arrangement was applied to the Eddystone tower. The optical apparatus consisted of parabolic reflectors of silvered copper, combined with argand burners, arranged on a four-sided frame, the best and most complete apparatus then known; and, as a means of further distinguishing the light, it was made to show red and white alternately, hence Sir Walter Scott's ‘ruddy gem of changeful light.’ Since the lighting of the Bell Rock not a single wreck has taken place on the reef. The Northern lighthouse board directed a bust of Stevenson, by Samuel Joseph, to be placed in the tower, and at his death placed in their minutes their regret at the loss of him ‘to whom is due the honour of conceiving and executing the great work of the Bell Rock Lighthouse.’

Not only was the tower itself novel in design, but the implements used in its erection had to be invented. The balance and movable jib cranes were for the first time used at the Bell Rock. The latter is now in universal use. Ball-bearings were also introduced into the cranes at the Bell Rock for the first time. Stevenson further designed for the temporary lightship moored off the Bell Rock tower during its construction—the first lightship placed in so deep water—a lantern to surround the mast, instead of small lanterns hung from the yard-arms or frames. This improvement is now universally adopted.

In 1814 Sir Walter Scott made his celebrated voyage round Scotland with Stevenson and the lighthouse commissioners, starting from Leith on 29 July and reaching Greenock on 8 Sept. On 30 July he visited the Bell Rock, and inscribed some appreciative lines in the lighthouse album. Speaking of Stevenson in his journal, he says: ‘The official chief of the expedition is Mr. Stevenson the surveyor—viceroy over the commissioners—a most gentlemanlike and modest man, and well known by his scientific skill.’

Stevenson's practice was not confined to lighthouses, but covered the whole field of general engineering. He designed many bridges. His Hutchison Bridge ‘is one of the best specimens of the segmental arch.’ He also designed a new form of suspension bridge, in which the roadway passes above the chains, and the necessity of tall piers is avoided; many bridges have since, especially on the continent, been constructed on this principle. He also suggested the modern rail used on railways. George Stephenson acknowledged that it was from Stevenson's description that he adopted malleable iron rails. He was the first to discover and point out that the salt waters of the ocean flow up the beds of rivers in a stream quite distinct from the overflowing fresh water; and he invented the hydrophore for procuring specimens of sea and river water, so largely used in estuarial and oceanic observations. Stevenson designed the magnificent eastern road approaches to Edinburgh; of one of the eastern approaches Cockburn wrote: ‘The effect was like drawing up the curtain of a theatre.’

His experiments on the destruction of timber by the Limnoria terebrans led to the universal adoption of greenheart oak for structures in the sea. He took a great interest in the promotion of the fisheries, and suggested and urged the use of the barometer by fishermen. He was one of the originators of the Royal Observatory of Edinburgh, and strongly advocated the importance to navigation of trustworthy charts founded on careful marine surveys and soundings. He was a fellow of the Royal, the Antiquarian, and Wernerian societies of Edinburgh; the Geological and Astronomical societies of London; and a member of the Institution of Civil Engineers (1828). Stevenson died at Edinburgh on 12 July 1850, and was buried in the New Calton cemetery, close to one of the approaches to Edinburgh which he designed. Joseph's marble bust of Stevenson is in the Bell Rock lighthouse. The original model is in the Museum of Science and Art, Edinburgh. A portrait painted from it is in the National Portrait Gallery, Edinburgh, and has been engraved for David Stevenson's ‘Life of Robert Stevenson,’ 1878.

Alan, his eldest, David his third son, and his youngest son, Thomas, are noticed separately. Stevenson contributed many articles on engineering to the ‘Edinburgh Encyclopædia’ and the ‘Encyclopædia Britannica,’ such as bridges, blasting, dredging, roads, lighthouses, railways. Among the papers he contributed to scientific societies, that contributed to the Wernerian Society on the ‘Alveus of the German Ocean’ is frequently quoted by geologists.

[Private information; David Stevenson's Life of Robert Stevenson, Edinburgh, 1878; Robert Louis Stevenson's Family of Engineers, in Edinburgh edition of his Works, 1896, vol. xviii.]

D. A. S.