Benjamin, (Thomas) Brooke

(1929-1995), mathematician and physicist

by M. S. Longuet-Higgins

© Oxford University Press 2004 All rights reserved

Benjamin, (Thomas) Brooke (1929-1995), mathematician and physicist, was born on 15 April 1929 at 5 The Laund, Wallasey, Cheshire, the eldest of the three children of Thomas Joseph Benjamin (1884-1960), solicitor and high-court registrar, and his wife, Ethel Mary (1900-1975), daughter of Henry Brooke, engineer, of Meols, the Wirral, Cheshire, and Mary Meadows, granddaughter of Sir William Brown. His father, who served with distinction in the First World War, was energetic but strict, and his mother more sympathetic and artistic; she was a good amateur pianist. At home and at his local primary school in Wallasey, which he attended between the ages of five and seven, Benjamin was early recognized as being exceptionally intelligent. When he was eight he was sent away, as was customary, to a preparatory boarding-school, where he was very unhappy though he shone scholastically. In 1939 he enrolled at Wallasey grammar school but, owing to the wartime bombing of Merseyside, the family moved to Mold, in north Wales, where the children attended the Alun county school. Among his hobbies at this time was constructing radio sets. In 1943 the family returned to Wallasey, where Benjamin became ill and was diagnosed with diabetes. His school years were spent partly at home, where school work was brought to him by his companions. He developed musically, saving up to buy a second-hand violin and writing a number of musical compositions, notably a string quartet (1948) and a piano quintet performed at a concert in Wallasey when he was sixteen. Despite his irregular school attendance he was strongly recommended by the discerning headmaster, Mr Allen, for a place at Liverpool University, to which he was admitted in 1947; he graduated BEng with first-class honours in 1950. He was active in the Liverpool University Music Society and conducted numerous performances in Liverpool and elsewhere, frequently of his own compositions. He helped to found the Liverpool Mozart Orchestra, and regularly conducted it. By this time he had also developed a strong social and political awareness, and spoke often in public as a pacifist and independent.

Faced with a decision between music and science as a profession, Benjamin chose science. In 1951 he was granted a Rotary foundation fellowship to study electronics at Yale University, where he gained an MEng in 1952. At the death of George VI he gave a local broadcast which won public praise. While at Yale he was approached by a medical researcher who instructed him how to inject himself with insulin in the precise amounts needed to counterbalance and widen his food intake. This treatment considerably improved his health and energy. After a short visit to the University of California, Berkeley, he befriended a Norwegian sea captain and returned to England on a cargo vessel via Manila and Singapore. He was accepted as a research student at King's College, Cambridge, in October 1952. There, with A. M. Binnie FRS, he devised ingenious and accurate new experiments to study cavitation in fluid flow. He also took a leading part in the musical activities of the college. In 1955 he was elected to a research fellowship at King's, which was subsequently twice renewed. In 1958 he was appointed assistant director of research jointly in the engineering department and in the department of applied mathematics and theoretical physics (DAMTP). An important development was when, unable to obtain other experimental facilities, and believing strongly that experiment and theory should go hand-in-hand, he turned to G. K. Batchelor, then head of the DAMTP, whom he persuaded to convert the basement at the department into a fluid mechanics laboratory. Among the significant experiments done there was Benjamin's discovery, together with his student J. E. Feir, of the essential instability of a regular train of water waves when the water depth exceeds a certain critical value. The analysis of this phenomenon, done by Benjamin, has much wider implications in physics, and has become known as the Benjamin-Feir instability.

While at Cambridge Benjamin published many other penetrating researches of a similar kind, having especially to do with the instabilities of different types of fluid motions. In 1967 he was promoted to a readership in hydrodynamics. On 9 July 1956 he married Helen Gilda-Marie Rakower Ginsburg (b. 1927), an American and a graduate of Stanford University, who had met him during his visit to Berkeley in 1952 and followed him to England. They had three children: Lesley, Joanna, and Peter. By 1970 the marriage had broken down and it was dissolved in 1974.

During the latter part of his time at Cambridge Benjamin became convinced that in order to understand certain fluid instabilities, particularly the annular flow between rotating cylinders, studied experimentally by G. I. Taylor, and the phenomenon of vortex breakdown behind the wings of aircraft, it was necessary to master the French school of nonlinear analysis, to which he accordingly devoted much attention. As a result of his studies he wrote a series of seminal papers in which he made theoretical predictions that were later confirmed by experiment. In 1970 Benjamin was appointed to a professorship at the University of Essex, where he set up the Fluid Mechanics Research Institute. Its explicit objective was to promote collaboration between mathematicians and experimentalists in fluid mechanics research. In this it was outstandingly successful, publishing over ninety research reports and attracting able visitors, especially mathematicians, from overseas. Benjamin also played a moderating role in the student unrest at the University of Essex in 1974, giving good and sympathetic advice to the students and even visiting them in gaol. In order to avoid violence during a student demonstration he marched at their head. While at Essex he met his second wife, Natalia Marie-Thérèse Court (b. 1944), whom he married on 25 February 1978. The marriage was supremely happy. A daughter, Victoria, was born in 1982.

Lacking ongoing support for his laboratory at Essex University, in 1978 Benjamin applied for and was subsequently appointed to the Sedleian chair of natural philosophy at Oxford, with a fellowship at Queen's College. He occupied the chair from 1980 until his death from lung cancer in 1995. During that time he held an appointment as adjunct professor at Pennsylvania State University, which he visited annually and which held a conference in honour of his sixtieth birthday in April 1989. At Oxford he had at first to do experiments in his own house, but later when he was joined by T. Mullin from London University he was granted facilities in the physics department. Ever concerned for students, he argued publicly for an overhaul of the system of degrees, supporting the option of a general degree, carrying equal prestige, for those students not intending to pursue an academic career. He also led a campaign against the Conservative government's policy towards the universities, which in his view tended to harm them and to underestimate their contribution to the country's economy. To this end he founded the National Conference of University Professors and was its first president. He supported the International Centre for Theoretical Physics in Trieste for its work for third-world young scientists.

Benjamin received many honours, including the Lewis F. Moody award from the American Society of Civil Engineers in 1966, and election to the Royal Society of London (1966), where he was twice a member of council and in 1992 gave the Bakerian lecture, entitled 'The mystery of vortex breakdown'. In 1969 he was awarded the William Hopkins prize of the Cambridge Philosophical Society. In 1993 he was elected a foreign member of the French Academy of Sciences. He received honorary degrees from the universities of Liverpool, Bath, and Brunel.

Benjamin, known to his friends as Brooke, was tall, modest, and always polite. Among his colleagues he inspired great admiration, affection, and loyalty. With a quiet sense of humour, he was inwardly sensitive and imaginative. In his later years he took to writing poetry to express his inner reactions to everyday occurrences. He never sought publication, though his poems can be moving and show both imagination and originality of form. He was justifiably proud that despite taking a leading part in many activities he made no known enemies. He died on 16 August 1995 at Oxford, survived by his wife, Natalia, their daughter, Victoria, and the three children of his first marriage, and was cremated at Oxford crematorium on 23 August.

M. S. LONGUET-HIGGINS

Sources  
report on the correspondence and papers of Thomas Brooke Benjamin, FRS (1929-1995) by the National Cataloguing Unit for the Archives of Contemporary Scientists, University of Bath, NCUACS 63/1/97, Bodl. Oxf.
reports from Fluid Mechanics Research Institute, 1970-78, University of Essex
registrar's certificate of career, 1 Nov 1950, U. Lpool
private information (2004) [Helen Benjamin, sister; Natalia Benjamin, widow; G. Morrison]
Liverpool Daily Post (15 April 1954)
Essex County Standard (2 April 1971); (31 March 1972)
Institute of Mathematics and its Applications, 31 (1995), 184-5
The Times (2 Sept 1995)
J. Hunt, 'Professor T. Brooke Benjamin', The Independent (28 Aug 1995)
m. cert. [Helen Gilda-Marie Ginsburg]
m. cert. [Natalia Marie-Thérèse Court]

Archives  
Bodl. Oxf., corresp. and MSS
priv. coll.

Likenesses  
photograph, c.1950, repro. in The Times
photograph, c.1950, repro. in Hunt, 'Professor T. Brooke Benjamin'
photograph, 1980, West Freedom Railway, Wisconsin
photograph, 1991
double portrait, photograph, 1992 (with his daughter Victoria)
photograph, 1992
photograph, 1993
photograph, RS [see illus.]

Wealth at death  
under £145,000: administration with will, 15 Dec 1995, CGPLA Eng. & Wales


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