week. After attending University College school from 1859 to 1864, he entered University College London in 1864-5, and in July 1865 and July 1866 took the Andrews mathematical scholarships for first and second year students respectively.
In 1867 he passed the first B.A. examination of the University of London, with second-class honours in mathematics, and entered the Indian telegraph service, being sent by government on passing the entrance examination to Glasgow to study electricity under (Sir) William Thomson, afterwards Lord Kelvin [q. v. Suppl. II]. Of his work in Kelvin's laboratory he gave a vivid account in 'The Times,' 8 Jan. 1908. After some practical study at the works of the Telegraph Construction and Maintenance Company he went out to Bombay in 1868, his appointment as assistant-superintendent of the fourth grade dating from 1 Sept. 1868. With Mr. C. L. Schwendler, electrician on special duty, he soon worked out methods of detecting faults which revolutionised the Indian overland system of telegraphs. In 1871 Ayrton was moved to Alipur ; returning on short leave, he married in London, on 21 Dec. 1871, his cousin, Matilda Chaplin [see Ayrton, Matilda Chaplin]. In 1872-3 he again returned to England for special investigations ; and was also placed in charge of the testing for the Great Western Railway telegraph factory under (Sir) William Thomson and Fleeming Jenkin [q. v.]. In 1873 the Japanese government founded the Imperial Engineering College at Tokio, which became for a time the largest technical university in the world. Ayrton accepted the chair of physics and telegraphy, and proceeding to Japan created a laboratory for teaching applied electricity. The first of its kind, this laboratory served as a model for those which Ayrton himself organised in England later, and through them for numerous other laboratories elsewhere. During the five years in Japan Ayrton with his colleague, Professor John Perry, carried out an extraordinarily large amount of experimental work ; their joint researches include the first determinations of the dielectric constant of gases and an important memoir on the significance of this constant in the definition of the electrostatic unit of quantity ; memoirs on the viscosity of dielectrics, the theory of terrestrial magnetism, on electrolytic polarisation, contact electricity, telegraphic tests, the thermal conductivity of stone, a remarkably ingenious solution of the mystery of Japanese * magic ' mirrors, and a paper interesting to the philosophy of aesthetics on 'The Music of Colour and Visible Motion.' In 1878 Ayrton returned, home and acted as scientific adviser to Messrs. (Josiah) Latimer Clark [q. v.] and Muirhead. In 1879 Ayrton became a professor of the City and Guilds of London Institute for the Advancement of Technical Education, an institution founded by certain City companies. He delivered the inaugural address on 1 Nov., and began the institute's work in the basement of the Middle Class Schools, Cowper Street. He and Professor Henry Edward Armstrong, F.R.S., the chemist, were at first the sole professors, and his first class consisted of an old man and a boy of fourteen. Perry soon joined the small staff and the movement spread rapidly. In 1881 the governors of the institute laid the foundation of two colleges, the Finsbury Technical College and the Central Technical (now the City and Guilds) College, South Kensington. Ayrton acted as professor of applied physics at Finsbury from 1881 till 1884, and then became first professor of physics and electrical engineering in the Central Technical College, a post which he held till his death.
Ayrton and Perry continued till about 1891 their scientific partnership ; in 1881 they invented the surface-contact system for electric railways with its truly absolute block system, which in 1882 they applied together with Fleeming Jenkin to 'telpherage,' a system of overhead transport used little in England, but to a greater extent in America.
In 1882 Ayrton and Perry brought out the first electric tricycle ; they next invented in rapid succession a whole series of portable electrical measuring instruments, an ammeter (so named by the inventors), an electric power meter, various forms of voltmeter, and an instrument for measuring self and mutual induction. Great use is made in these instruments of an ingeniously devised flat spiral spring which yields a relatively great rotation for a small axial elongation. The instruments have served as prototypes for the measuring instruments which have come into use in all countries, as electric power has become generally employed for domestic and commercial purposes. Ayrton and Perry also invented a clock meter and motor meter which served as models for the meters now used, and would have brought them an immense fortune, had they not abandoned their patents at too early a date. Of the instruments other than electric invented by
