Ewing, James Alfred
Ewing, James Alfred
(b. Dundee, Scotland, 27 March 1855; d. Cambridge, England, 7 January 1935)
Ewing’s most important research dealt with magnetism. He was one of the first to observe the phenomenon of hysteresis, which he named and studied both experimentally and theoretically. He also did research in seismography and thermodynamics. Although his research was important, Ewing was probably more influential through his continuing efforts to establish engineering education. In three quite different positions—as professor of mechanical engineering in Tokyo, as director of naval education, and as professor at Cambridge—he was involved with the teaching of engineering. In addition, he published many papers and books and participated in numerous committees dealing with engineering problems and the application of science.
Ewing’s father was a minister of the Free Church of Scotland; both his brothers became clergymen. Ewing studied at the Dundee high school and then went to the University of Edinburgh on an engineering scholarship. A good student, he came under the influence of Peter Tait and Fleeming Jenkin. Ewing did some early research with Jenkin on the harmonic analysis of vowel sounds (using the traces produced by Edison’s phonograph). Through Jenkin, Ewing came in contact with William Thomson and participated in three expeditions for laying transatlantic telegraph cables.
Following Jenkin’s recommendation, Ewing went to Japan in 1878 as professor of mechanical engineering at the University of Tokyo. The university provided Ewing with the means to establish a seismological observatory and, beginning in the winter of 1879–1880, he erected instruments and recorded earthquakes. Ewing was especially eager to obtain a continuous record of motion during an earthquake, and he devised a new type of seismograph for this purpose. In the latter part of his stay in Tokyo he was involved in teaching physics and began his experimental study of magnetism. He later received the Japanese Order of the Precious Treasure.
Ewing returned to England in 1883, after five years in Japan. At first he held the chair of engineering at the University of Dundee and continued his research on magnetism. In 1890 Ewing was made professor of mechanism and applied mechanics at Cambridge University. There was at the time disagreement within the university over its involvement with engineering education, and there were some who believed that the subject had no place at Cambridge. (The engineering professorship held by James Stuart, Ewing’s predecessor, was not supposed to be renewed.) During Ewing’s tenure engineering became accepted, and in 1892 the mechanical sciences tripos was established.
Ewing was director of naval education from 1903 to 1916. Lord Selborne and Admiral John Fisher appointed him to this position as part of their program to reform education in the British navy and to provide training in science and engineering. During World War I he was in charge of “Room 40,” a group that intercepted and deciphered German messages.
From 1916 to 1929 Ewing was principal and vicechancellor of the University of Edinburgh and was active in its expansion—constructing new buildings, founding new chairs, and enlarging the staff. He received honorary degrees from the universities of Oxford, Cambridge, Durham, and St. Andrews. He was made a fellow of the Royal Society in 1887 and received the Royal Medal for his research on magnetism in 1895. He was knighted in 1911 and made honorary member of the Institution of Civil Engineers in 1929 and of the Institution of Mechanical Engineers in 1932.
Ewing began his research on magnetic hysteresis through a project to study the effect of stress on the thermoelectric properties of metals. In 1881 he discovered that the thermoelectric effect lags behind the applied stress. He next suggested that other pairs of variables might also be related in such a cyclic manner, and he studied the transient currents produced by twisting a magnetized wire. He found a lag here also and introduced the term hysteresis, from the Greek word meaning “to be late,” to describe it. Ewing then turned to the study of hysteresis in magnetization. He observed in 1882 that the area enclosed by the hysteresis loop is proportional to the work done during a complete cycle of magnetization and demagnetization. In 1885 he presented an important paper on this topic to the Royal Society.
The lag, in some processes, between a force and its effect was known in Germany before Ewing’s experiments, and Kohlrausch had invented the term elastische Nachwirkung for it in 1866. In his 1885 paper Ewing noted that Emil Warburg had independently discovered magnetic hysteresis and had emphasized the physical importance of the area of the hysteresis loop (“Magnetische Untersuchungen,” in Annalen der Physik und Chemie, 13 , 141–164).
I. Original Works. Ewing’s writings include “On Friction Between Surfaces Moving at Low Speeds,” in Proceedings of the Royal Society, 26 (1877), 93–94, written with Fleeming Jenkin; “On the Harmonic Analysis of Certain Vowel Sounds,” in Transactions of the Royal Society of Edinburgh, 28 (1878), 745–777, written with Fleeming Jenkin; “On a New Seismograph,” in Proceedings of the Royal Society, 31 (1881), 440–446; “Effects of Stress on the Thermoelectric Quality of Metals,” ibid., 32 (1881), 399–402; “On the Production of Transient Electric Currents in Iron and Steel Conductors by Twisting Them When Magnetised or by Magnetising Them When Twisted,” ibid., 33 (1881–1882), 21–23; “On Effects of Retentiveness in the Magnetisation of Iron and Steel,” ibid., 34 (188–1883), 39–45; “Earthquake Measurement,” in Memoirs of the Science Department of the University of Tokyo, 9 (1883), 1–92; “Experimental Researches in Magnetism,” in Philosophical Transactions of the Royal Society, 176 (1885), 523–640; “Contributions to the Molecular Theory of Induced Magnetism,” in proceedings of the Royal Society, 48 (1890), 342–358; Magnetic Induction in Iron and other Metals (London, 1892); Steam Engine and Other Heat Engines (Cambridge, 1894); The Strength of Materials (Cambridge, 1899); The Mechanical Production of Cold (Cambridge, 1908); Thermodynamics for Engineers (Cambridge, 1920); and “An Engineer’s Outlook,” in Nature, 130 (1932), 341–350.
For a more extensive listing of Ewing’s papers, see the Catalogue of Scientific Papers of the Royal Society, IX (London, 1891), and XIV (London, 1915).
II. Secondary Literature. On Ewing’s life and work, see R. T. Glazebrook, “James Alfred Ewing,” in Obituary Notices of the Royal Society, I (London, 1932–1935), 475–492; and E. Griffiths, “Sir Alfred Ewing,” in Proceedings of the Physical Society, 47 (1935), 1135.