CLARK, WILLIAM TIERNEY, a civil engineer, was born nt Sion House, Somerectehire, August 23, 1783. He was apprenticed when very young to a millwright in Bristol, and followed the trade for several years in that city and at Colebrookdale. In 1808 he removed to London, and entered the service of the late Mr. Rennie as draughts man; and held the employment until 1811, when he was appointed engineer of the West 3liddlesex Waterworks. The establishment was at that time on a very small scale—an engine of twenty-horse power supplying the neighbouring hamlets from an insufficient reservoir, yielding no profit to the company. But under Mr. Clerk's advice the works were enlarged, and he spared no exertion to render them com plete and effectual, until at last there were three pumping-engines of the aggregate power of 245 horses, and reservoirs capacious enough to contain from 85 to 40 million gallons, and producing an annual rental of nearly 70.000/. This post he retained for the rest of his life.
In 1819 Mr. Clark undertook to complete the Thames and Medway Canal, a work which bad been stopped for want of capital, and under his direction it was finished some years afterwards; and the great tunnel through the Frindsbury hills remains as a solid proof of his ability. His next work was the suspension-bridge over the Thames at Hammersmith, which was commenced in 1824 and finished in 1827. It is chiefly remarkable for the small deflection of the chains between the chord-line or points of suspension. The snapension-bridge at Marlow was also designed by Mr. Clark, and be was employed by the late Duke of Norfolk to build one over the Arun.
Mr. Clark was however beet known by the suspension-bridge which he constructed across the Danube at Pesth. It was begun in 1839 and finished in 1849, at a cost of 622,000/. At times the bursting of dams and the pressure from accumulated ice in the winter threatened a total stoppage of the works, but all obstacles were overcome by the energy and perseverance of Mr. Clark, and the bridge remains an admirable monument of his genius and skill. To quote his own words from the volume in which he describes the bridge, it "encountered probably more difficulties than any structure of a similar kind in existence. The magnitude of the river over which it is thrown, the depth and nature of its bed, and the velocity of the current, created the misgivings, at one time almost universal in Hungary, that no permanent communication could ever be established across the Danube between Buda and Pesth. The moral difficulties to be overcome, no leas than the physical obstacles, were very great. Pride, prejudice, and jealousy, had each to be encountered." Mr. Clark received a box set in brilliants from the Emperor of Austria in token of his approbation at the suc cessful completion of the bridge, and the late Emperor of Russia sent him a first-class gold medal in return for a design for a magnificent suspension-bridge to be erected across the Neva.
Mr. Clark was elected a Fellow of the Royal Society in 1837 ; he was a Fellow also of the Astronomical Society, and a member of the Institution of Civil Engineers. He died September 22, 1852.