by G. B. Jeffery, rev. Alan Yoshioka
© Oxford University Press 2004 All rights reserved
Filon, Louis Napoleon George (1875-1937), mathematical physicist and university administrator, was born at St Cloud, near Paris, on 22 November 1875, the only son of Pierre Marie Augustin Filon, littérateur and tutor to the prince imperial, and his wife, Marie Jeanne Madeline Poirel. When he was three years old his parents, his father then blind and his mother in delicate health, moved to England and settled in Margate. His early education under the personal direction of his father centred on the classics. He went to Herne House School, Margate, and in 1894 became a student at University College, London, where he graduated BA with first-class honours in 1896, and was awarded a gold medal for Greek. He came to mathematics only because it was at that time part of the curriculum for the BA degree. This brought him into contact with Karl Pearson and Micaiah Hill for whom he retained throughout life an abiding affection and reverence, and it was their influence which very largely shaped his subsequent career as a mathematician and scientist.
In 1898 (the year in which he was naturalized) Filon went to King's College, Cambridge, on a 1851 Exhibition scholarship, as one of the earliest 'advanced students'; he then joined the staff of University College, London, as lecturer in pure mathematics in 1903. In 1904 Filon married Anne, eldest daughter of Professor Philippe Godet, of the University of Neuchâtel. They had one son and two daughters. In 1909 he joined the University of London Officers' Training Corps, which he would later command (1926-32). He saw active service with the British expeditionary force in France, and was invalided home in 1915. He subsequently commanded the 2nd battalion London regiment, and was demobilized in 1919. In later years he served on the technical staff of the Admiralty air service, and of the Air Board.
Filon was elected to the Royal Society on 5 May 1910 as a 'distinguished mathematician and physicist' (list of candidates, 1910, RS). In 1912 he succeeded Pearson in the Goldsmid chair of applied mathematics and mechanics, to the work of which he devoted the rest of his life. The results of his mathematical researches are embodied in over fifty memoirs, spread over forty years. They are concerned with many aspects of mathematics, but his outstanding contributions were in the field of classical mechanics and particularly the mechanics of continuous media, where the problems still outstanding usually presented formidable technical difficulties, with which he was well equipped both by temperament and training to wrestle. His greatest achievement in mechanics was the theory of 'generalized plane stress' which shows how the average elastic stresses in a thick plate may be determined by the simpler analysis appropriate to two-dimensional problems. A development of this theory shows how the optical measurement of the stresses in a transparent celluloid plate may be used to investigate the stresses in a steel structure. It was a particular source of gratification to him when, in association with E. G. Coker, he was able to apply the method to the exploration of the stresses in structures actually used in engineering practice. Together they wrote the classic Treatise on Photoelasticity (1931). Filon also produced A Manual of Photoelasticity for Engineers (1936).
Filon was a great teacher. He regarded mechanics as a branch of physics rather than of mathematics. He insisted both that the theory of mechanics should be developed through the application of rigorous logic and that theory should yield its results in a form that could be tested by experiment. Thus, his lectures on mechanics were freely illustrated by experiment and he established a mechanics laboratory in which his mathematics undergraduate students carried out experiments.
Filon took an active part in the affairs of the University of London in the critical phase of its development and unification. His diligent statesmanship was credited with resolution of long-standing antagonism between the university's internal and external sides. He was a member of the senate (1920) and the court, dean of the faculty of science, and chairman of the academic council (1924-33). During his term as vice-chancellor (1933-5), the foundation stone was laid for the university's monumental headquarters. He was a passionate believer in academic freedom, working tirelessly to extend and develop teaching and research, and on that basis fought against the Haldane report of 1913. For years he carried out a full lecturing timetable every morning and a full programme of committees and councils every afternoon, and throughout this time, a colleague reflected, every lecture was prepared and every document studied with almost excessive attention to detail.
Filon was vigorous and combative, a man of strong convictions, yet considered just and generous, and a constant help and inspiration to those with whom he worked. From 1929 until his death he was director of the university observatory. He was appointed CBE in 1933, was vice-president of the Royal Society from 1935, and president of the Mathematical Association. He died at his home, Godwin House, St Augustine's Avenue, Croydon, on 29 December 1937, a victim of a local epidemic of typhoid.
G. B. JEFFERY, rev. ALAN YOSHIOKA
Sources
G. B. Jeffery, Obits. FRS, 2 (1936-8), 501-9
The Times (30 Dec 1937)
The Times (31 Dec 1937)
H. T. Jessop and others, Photoelasticity at University College London: jubilee commemoration of the work of E. G. Coker & L. N. G. Filon from 1909 to 1937 (1959)
E. N., Nature, 141 (1938), 357-8
G. B. Jeffery, Mathematical Gazette, 22 (1938), 1-2
CGPLA Eng. & Wales (1938)
election certificate, RS
Archives
CAC Cam., corresp. with A. U. Hill
UCL, Karl Pearson MSS
Likenesses
W. Stoneman, photograph, 1918, NPG
B. P. Hughes, oils, c.1930, U. Lond.
photograph, repro. in Obits. FRS
photograph, repro. in Jeffery, Mathematical Gazette
photograph, RS
Wealth at death
£12,340 17s. 7d.: probate, 6 April 1938, CGPLA Eng. & Wales
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