supplying Nottingham, and continued in that position until the year 1880, when the companies were bought out by the municipal authorities of Nottingham. About 1847 he invented, in conj unction withWilliam George (afterwards Lord) Armstrong [q.v. Suppl.], a self-acting valve designed to close the pipe automatically when the velocity of the water passing through it exceeds a certain limit ; the invention is still largely used by water companies.
There is scarcely a large city in the kingdom which did not make use of Hawksley's services at one time or another, but the three cities with which he had the closest connection were Liverpool, Sheffield, and Leicester. His connection with the water supply of the city of Liverpool began in 1846, when he recommended the Rivington-Pike scheme, which was at length adopted, and completed in 1857. The rapid growth of Liverpool, however, made it necessary to cast about for a further supply of water, and in 1874 a scheme for supplying the city from the head waters of the river Severn was drawn up, and the reports were referred to Hawksley and John Frederic Latrobe Bateman [q. v. Suppl.] for their consideration. Hawksley reported in favour of the Vyrnwy scheme, which was eventually carried out, and Hawksley was appointed engineer-in-chief to the undertaking, an office which he held until his retirement in 1885. This scheme involved the construction of a very large masonry dam across the valley of the Vyrnwy, and the creation of an artificial lake almost as large as any natural lake in the kingdom. It is probably the most important scheme which has been completed in this country up to the present time.
Hawksley's connection with Sheffield was brought about in 1864 by the terrible disaster due to the bursting of the masonry dam of the Dale Dike reservoir on 11 March 1864. He was called in with other engineers to advise and report on this accident and to prepare plans for other works for supplying the city of Sheffield. He remained engineer-in-chief of these works until his death.
At Leicester he was responsible for and planned the Thornton Park reservoir and the Bradgate reservoir.
The skill which Hawksley showed in working out his estimates for the water supply of any district upon which he was consulted mainly depended upon the elaborate preliminary calculations he always made, based on rainfall and evaporation measurements taken throughout the district. To Hawksley also is really due the introduction of the 'constant service' system.
In addition to waterworks Hawksley was also responsible for numerous gas supply and drainage works ; he served as president of the Gas Managers' Association from 1864 to 1867; and he was one of the authorities consulted in 1857 in connection with the London main drainage scheme. It is, however, as a waterworks engineer that he will always be known; no other engineer in this country during the nineteenth century has carried out so many works, or has been recognised as such an authority upon this branch of engineering.
He became a member of the Institution of Civil Engineers in 1840, was elected to the council in 1853, and served as president in the years 1872-3. He also served as president of the Institution of Mechanical Engineers in 1876 and 1877, and in recognition of his high scientific and engineering attainments he was elected a F.R.S. in 1878.
He furnished numerous reports to foreign governments on engineering questions, mainly on waterworks and sewage works, and as a result received numerous foreign orders. He was made commander of the order of Francis Joseph of Austria, was a commander of the Rose of Brazil, and was a member of the Swedish order of the Polar Star, and Knight of the Danebrog.
Hawksley was a good mathematician, and took a keen interest in questions of statistics. In 1876 he gave an address at St. George's Hall, Liverpool, as president of the health section of the Association of Social Science, dealing with the application of statistics to various social problems.
He was twice married : in 1831 to Phillis, daughter of Francis Wright of Nottingham, by whom he had several children. His son, Mr. Charles Hawksley, is an eminent engineer. She died in 1854, and in 1855 he married Eliza, daughter of J.Litt. Hawksley died on 23 Sept. 1893, at his residence, 14 Phillimore Gardens, Kensington, at the age of eighty-six.
In the year 1887 his portrait, painted by Mr. Hubert Herkomer, R.A., was presented to him by many friends in the engineering and legal professions, as a mark of esteem and affection (Times, 14 July 1887). A replica of this oil painting was executed for the Institution of Civil Engineers.
His literary work was entirely confined to his professional reports and presidential addresses : Reports on Water Supply, Leicester (Nottingham, 1850) ; Edinburgh (London, 1872) ; Main Drainage of London (London, 1858).
[Obituary notices in Proc. Inst. Civil Engineers, vol. cxvii. ; Times, 25 Sept. 1893.]