Bates, Leslie Fleetwood

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(b. Bristol, England, 7 March 1897; d. Nottingham, FngkuuF, 20 January 1978)


Bates was the eldest of six children of William Fleetwood Bates and Henrietta Anne Pearce. He was brought up in the Kingswood district of Bristol, where his father, an ardent pacifist, was a clerk in a hoot factory. Although his parents were Church of England, at the age of seven Bates attached himself to the Moravian church. Later, in India, he joined the Scottish Presbyterian church (probably for lack of a Moravian mission there). But upon returning to England, Bates suddenly eschewed organized religion, though he continued to quote the Bible freely. A colleague described him as a “secular Christian,”

Bales was first educated at a small local council school, from which in 1909 he won a scholarship to the Merchant Venturers Secondary School—a good though not distinguished institution. In 1913 Bates won a scholarship to Bristol University, which he entered with the intention of gaining an honors degree in physics. The outbreak of war frustrated this goal so he took a pass degree (B.Sc.) in physics and mathematics in 1916 and then qualified as a radiographer in the Royal Army Medical Corps, in which he served as a lieutenant in India until 1920.

On returning home he sought a grant to enable him to qualify in medicine. When this was refused, he returned to the physics department at Bristol as a demonstrator. There A. P. Chattock and W. Sucksmith were engaged in fruitful research on ferro-magnetism, and Bates collaborated with them on measurements of the Richardson gyromagnetic ratio. Thus began his lifelong fascination with this field of physics.

Briefly, however. Bates’s attention turned to the investigation of long-range α particles. In 1922 he was awarded a state grant to work for a Ph.D. in the Cavendish Laboratory at Cambridge under Ernest Rutherford.

In 1924 Bates returned to research on ferromagnetism following his appointment as assistant lecturer in physics at University College, London; by 1930 he had been promoted, rapidly, to the level of reader. Encouraged by the enthusiastic but sometimes irascible experimentalist Edward N. da Costa Andrade, who was appointed professor in 1928, Bates began a long investigation of the ferromagnetic properties of manganese compounds, especially those with phosphorus and arsenic, that have Curie points around room temperature. He measured a range of physical properties, including susceptibility, electrical resistivity, and specific heats. To make the pure manganese he required, he developed a technique of preparing the amalgam by electrolysis. This led him to investigate the properties of amalgams of ferromagnetic metals.

Apart from launching Bates on his research career, the London appointment gave him financial security. In 1925 he married Winifred Frances Furze Ridler, a graduate in botany of Bristol University whom he had met there after returning from India; they had a son and a daughter. They had a common interest in science—Bates had read quite deeply in biology. The marriage was long and happy, lasting more than forty years.

In 1936 Bates transferred his research activities to Nottingham, where he was appointed Lancashire-Spencer professor of physics in its University College, then affiliated with London University (it was granted full university status in 1948). There he continued his work on amalgams and, from about 1940, extended it into the field of thermomagnetic measurements to determine temperature changes during the hysteresis cycle. During the war Bates’s deep knowledge of magnetic phenomena was utilized by the Inter-Services Research Bureau, especially in the degaussing of ships to protect them from magnetic mines, After the war (1946–1956) he was consultant to the Admiralty Compass Laboratory. From 1957 to 1966 he was secretary of the Magnetism Commission of the International Union of Pure and Applied Physics.

About 1950 Bates turned his attention to the powder pattern technique developed by Francis Bitter at M.I.T. This was a valuable method of delineating magnetic domain structure, and over the period 1950 to 1965 he published nearly fifty papers on this subject alone. From about 1954 he investigated, in association with the Atomic Energy Research Establishment at Harwell, the magnetic and other physical properties of a number of metals of interest to the British atomic energy program, notably uranium and thorium. In the postwar years Bates remained a keen and active research worker, but he was increasingly involved in administrative work in his department and the university, of which he was deputy vice-chancellor from 1953 to 1956.

Bates’s comprehensive knowledge of ferromagnetic phenomena was distilled in 1939 into his Modern Magnetism, of which four editions were printed. His standing in this field was recognized by the award of the Holweck Prize and Medal (jointly by the Physical Society of London and the Société Française de Physique) in 1949. He was elected fellow of the Royal Society in 1950.

Bates’s scientific merit has been variously assessed by his contemporaries: probably a fair consensus is that he fell short of brilliance but within his chosen field achieved, by patience and dedication, a wealth of results that have stood the test of time. Rutherford described him as somebody “who would probably not fly over hedges but who would nevertheless get there in the end.” However, it must be said that this opinion was given early in his career and on the strength of his α particle research, which Bates did not find very congenial.


A complete bibliography is in N. Kurti’s memoir on Bales in Biographical Memoirs of Fellows of the Royal Society. 29 (1983): it lists 160 publications from the period 1920 to 1977. His Modern Magnetism was first published in 1939 and went through four editions (last printing 1963). After his death Bates’s voluminous papers were cataloged by the Contemporary Scientific Archives Centre at Oxford; they are now al Nottingham University Library.

Trevor I. Willaims