Watson-Watt, Robert Alexander

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(b. Brechin, Aberdeenshire, Scotland, 13 April 1892; d. Inverness, Inverness-shire, Scotland, 5 December 1973)

radio engineering, meteorological physics.

R. A. W. Watt (the hyphen came with knighthood) was the son of Patrick and Mary (Matthew) Watt. He attended local schools in Brechin and University College, Dundee, then affiliated with the University of St. Andrews, from which he received the B.Sc. in electrical engineering with distinction in 1912; in 1919 he also qualified for the B.sc. in physics from the University of London. In 1912 he became an assistant professor of physics at University College, Dundee. During World War I he served in the government Meteorological Office, where he attempted to use radio direction-finding methods to locate thunderstorms. His wartime suggestion that two or more intersecting bearings displayed on a cathoderay oscilloscope could solve the problem of catching the characteristically short bursts of atmospherics generated by thunderstorms was not realized until 1923, when reliable cathode-ray tubes were developed in the United States. The work was continued at the Radio Research Station at Slough (under Watson-Watt as the superintendent) and in 1927 was assigned to the Department of Scientific and Industrial Research (D.S.I.R.), under whose auspices considerable success was achieved in locating not only thunderstorms but also naval signals. Watson-Watt’s radio research laboratory also investigated the ionosphere (a term he coined), not by the frequency-shift method used by Appleton but by the pulse method developed in the United States by Breit and Tuve. In that way Watson-Watt gained expertise in radio direction finding, cathode-ray displays, and pulse techniques.

That knowledge made him the obvious person to be consulted when H. E. Wimperis, the research director at the Air Ministry, wanted to know whether enough energy could be concentrated in a radio beam to disable an enemy aircraft or pilot. The answer, based on a calculation made by Watson-Watt’s assistant A. F. Wilkins at Slough, was negative, but the two men went on to calculate the feasibility of locating an aircraft from the reflected signal, this time with a positive result. Their calculation was contained in a secret memorandum dated 12 February 1935.

In his autobiography, Three Steps to Victory (1957), Watson-Watt asserted that this memorandum must be regarded “as marking the birth of radar and as being in fact the invention of radar,” despite the fact that earlier work toward locating objects by electromagnetic waves had been done in several countries, including Britain, Moreover, when he published his autobiography, he was engaged in a struggle for reward and recognition, so his assertion could be interpreted as self-serving. Nevertheless, he was right, for several reasons. The earlier trials had been done with continuous-wave transmissions at metric and longer wavelengths, without any thought being given to translation of the results into operational commands. Watson-Watt, however, stressed the importance of pulsed signals at decimetric and shorter wavelengths and sketched a manmachine system that would back up the equipment with a team of operators who would produce a display of information on the basis of which tactical decisions could be made. That model grew into the mainstream of the subsequent development of radar, with immediate important consequences. The British government authorized the construction of the “Chain Home” (CH) radar stations, first around the approaches to London and later along the entire south and east coasts of Britain, together with a system of control rooms whose command of the tactical situation is generally acknowledged to have tipped the balance against German attackers during the Battle of Britain in 1940.

Developments in other countries lagged behind those in Britain, both technically and operationally. Among data that may be cited in that connection is the failure of American radar during the Japanese attack at Pearl Harbor in 1941 (sixteen months after the Battle of Britain); the attackers were detected, though not unequivocally, but no system for utilizing this information was in place, and no defense could be organized. Thus, it is not too much to say that Watson-Watt did indeed invent radar.

Watson-Watt’s research team was transferred to the Air Ministry in 1936, and he directed it until 1938, when he handed it over to A. P. Rowe and went on to a succession of advisory posts at the ministry. After the war he went into private practice as a consultant, served as adviser to the government and leader of delegations to international meetings, and (after 1952) lived in Canada and the United States as a free-lance technical consultant. That year he and Margaret Robertson (whom he had married in 1916) were divorced; he later married Jean Smith, who died in 1964. In 1966 he married Katherine Jane Trefusis-Forbes. There were no children.

He was elected fellow of the Royal Society of London in 1941 and was knighted in 1942. He received the U.S. Medal for Merit, the Hughes Medal of the Royal Society, and the Elliott Cresson Medal of the Franklin Institute.


I. Original Works. The autobiography Three Steps to Victory: A Personal Account by Radar’s Greatest Pioneer . . . (London, 1957) was reissued in the United States in a substantially abbreviated version, The Pulse of Radar (New York, 1959). Both contain the full text of the 1935 memorandum “Detection and Location of Aircraft by Radio Methods.” Of special historical interest is a speech made by Watson-Watt at the postwar conference on radiolocation called by the Institution of Electrical Engineers, in which he paid tribute to the wartime contributions of American colleagues, in Journal of the Institution of Electrical Engineers, 93 , IIIA (1946), 11.

II. Secondary Literature. A portrait and a biography (with a list of publications) by J. A. Ratcliffe appears in Biographical Memoirs of Fellows of the Royal Society, 21 (1975), 549–568. On the question of priority in the invention of radar, see Charles Süsskind, “Who Invented Radar?” in Endeavour, n.s. 9 (1985), 92–96; and R.W. Burns, ed., The History, of Radar Development to 1945 (London, 1988), The last two references also contain the text of the 1935 memorandum.

Charles SÜsskind