# Dictionary of National Biography, 1912 supplement/Cardew, Philip

​CARDEW, PHILIP (1851–1910), major R.E., born at Oakshade, near Leatherhead, Surrey, on 24 Sept. 1851, was eldest son in a family of four sons and four daughters of Captain Christopher Baldock Cardew, 74th highlanders, of East Hill, Liss (son of Lieut.-general George Cardew, colonel com- mandant royal engineers), by his wife Eliza Jane, second daughter of Sir Richard Bethell, first Baron Westbury [q. v.]. Educated at Guildford grammar-school, he passed first into the Royal Military Academy, Woolwich, in 1868, and left it at the head of his batch. He was awarded the Pollock medal and the sword of honour, and received a commission as lieutenant in the royal engineers on 4 Jan. 1871. After two years at Chatham, Cardew was sent to Aldershot and Portsmouth; from September 1873 to April 1874 he was employed at the war office on defences; and, after a year at Glasgow, went to Bermuda in May 1875. He was placed in charge of military telegraphs, and joined the submarine mining service, engaging in the application of electricity to military purposes, which was to be the pursuit of his life. At the end of 1876 he was transferred to Chatham, where the headquarters of the submarine mining was on board ​H.M.S. Hood, which lay in the Medway off Gillingham. In 1878 he was acting adjutant of the submarine miners at Portsmouth, and became in the same year (1 April) assistant instructor in electricity at Chatham.
In addition to his work of instruction Cardew assisted in carrying out some important experiments with electric search-light apparatus for the royal engineers committee, at a time when the subject was in its infancy. The need of better instruments for such work led him to design a galvanometer for measuring large currents of electricity (cf. description in paper, read before Institution of Electrical Engineers, 25 May 1882). He next evolved the idea of the hot-wire galvanometer, or voltmeter, the value of which was universally recognised among electricians. He was awarded the gold medal for this invention at the Inventions Exhibition in London of 1885. He also originated a method of finding the efficiency of a dynamo.
Cardew's invention of the vibratory transmitter for telegraphy was perhaps his most important discovery, and in the case of faulty lines proved most useful, not only on active service in the Nile expedition and in India, but also during heavy snowstorms at home. Cardew received a money reward for this invention, half from the imperial and half from the Indian government. The utility of the invention was much extended by Cardew's further invention of 'separators,' consisting of a combination of 'choking coil' and two condensers. These instruments enable a vibrating telegraph circuit to be super-imposed on an ordinary Morse circuit without interference between the two, thus doubling the message-carrying capability of the line. His apparatus for testing lightning conductors was adopted by the war department for service.
Promoted captain on 4 Jan. 1883, and major on 12 April 1889, Cardew was from 1 April 1882 instructor in electricity at Chatham. On 1 April 1889 he was appointed the first electrical adviser to the board of trade. He held a long inquiry into the various proposals for the electric lighting of London, and drew up valuable regulations concerning the supply of electricity for power and for light. Cardew retired from the royal engineers on 24 Oct. 1894, and from the board of trade in 1898. He then entered into partnership with Sir William Preece & Sons, consulting engineers, and was actively engaged on large admiralty orders, involving an expenditure of 1,500,000l. He joined the board of the London, Brighton and South Coast railway in 1902. Cardew paid two visits to Sydney, New South Wales, in connection with the city's electrical installations. Soon after his return home from the second visit in 1909, by way of Japan and Siberia, he died on 17 May 1910 at his residence, Crownpits House, Godalming. In 1881 Cardew wrote a paper on 'The application of dynamo electric machines to railway rolling stock'; in 1894 he contributed a paper to the Royal Society on 'Uni-directional currents to earth from alternate current systems'; and in 1901 he delivered the Cantor lecture before the Society of Arts on 'Electric railways.' He contributed several papers to the Institution of Electrical Engineers, on whose council he served for many years, and was vice-president in 1901-2.
Cardew married in London, on 19 June 1879, his first cousin, Mary Annunziata, daughter of Mansfield Parkyns [q. v.], the Abyssinian traveller. She survived him with three sons and two daughters.
[War Office Records; R. E. Records; Memoirs in Royal Engineers Journal, 1910, by Major L. Darwin and others; Porter, History of the Corps of Royal Engineers, 1889, 2 vols.; Brown, History of Submarine Mining in the British Army, 1910.]
R. H. V.