Clark, Josiah Latimer

(b. Great Marlow Buckinghamshire, England, 10 March 1822; d. London, England, 30 October 1898),

technology.

With early experience as a chemist, Clark joined his brother Edwin first as a civil engineer and then, in 1850, as an assistant engineer in a telegraphy company. From that time on, his major interest was electricity, especially submarine telegraphy. He exhibited an extreme bent for practicality, perhaps best illustrated by a letter to the editor of Engineer in 1885 that argued that a separate set of easily remembered symbols should be established for working electricians, using the initial letters of volt, ampere, ohm for voltage, current, resistance, and so on. He was instrumental in the founding of the Society of Telegraphic Engineers and Electricians (later the Institute of Electrial Engineers) and was its fourth president.

Clark interst in practical telegraphic matters led him into investigations of some scientific importance. In 1863 he demonstrated that the speed of a current pulse was indepent of the voltage applied. A decade earlier he had shown that the retardation effects in telegraph cables were caused by induction; this information was then expanded upon by Faraday (Experimental Researches, III, 508–517). Clark developed a zinc-mercury standard cell that was widely used for both technological and scientific purpose. In 1861 he and Charles Bright presented a paper to the British Association suggesting the establishment of standard electrical units; their reasoning, again, was highly practical. This led to the formation of the important Committee on Standards, on which Clark served until it was temporarily disbanded in 1870.

Clark had a strong a vocational interest in astronomy; in 1857 he helped Airy, the astronomer royal develop a telegraphic system for reporting Greenwich mean time throughtout the country.

BIBLIOGRAPHY

I. Original Works. Clarks include the paper presented to the British Association, “Measurement of Electrical Quantities and Resistance,” in A Journal of Telegraphy1 (1861) 3–4, written with Charles Bright; and “On a Standard Voltaic Battery,” in Philosophical Transactions of the Royal Society164 (1874) 1–14. OPther papres are listed in the Royal Society, Cataloogue of Scientific Paper. His books include An Elementary Treatise Electrical Measurement (London 1868); and Dictionary of Metric and Other Useful Measures (London 1891). Other books are cited in the Dictionary of National Biography entry mentioned below.

II. Secondary Literature. Among the obituary notices the best is in Journal of the Institute of Electrical Engineers28 (1899), 667–672; that in Electrician42 (1899), 33, is accompanied by a photograph. There is an article on Clark in Dictionary of National Biography, Supp. 1, and another in J. T. Humphreys Celebrities of the Day (London 1881).

See also the introduction to William D. Weaver, Catalougue of the Wheeler Gift of Books, Pamphlets, and Periodicals to the Library of the American Institute of Electrical Engineers (New York, 1909), 1 , 15–46; the collection was originally assembled by Clark.

Bernard S. Finn