Died: 11 May 2012 in Manchester, England

Fritz Ursell's parents were Siegfried Ursell (1879-1947) and Leonore Helene Mayer (1893-1988). Siegfried was a paediatrician and, from 1914 to 1918, during World War I, he had served as a doctor in the German Army. Leonore had trained as a primary school teacher but, from 1914 to 1918, during World War I, she had served as a nurse in a hospital. Both Siegfried and Leonore were Jewish, from Jewish families that had lived in Germany for hundreds of years. Fritz, who had one sister, began his schooling in a kindergarten and all went well until 1933 when the Ursell family's troubles began.

Adolf Hitler became Chancellor of the German Reich on 30 January 1933. He quickly moved to rid himself of rivals both inside and outside his party. On 1 April 1933 there was the so-called "boycott day" when Jewish shops were boycotted and Jewish lecturers were not allowed to enter universities. On 7 April 1933 the 'Civil Service Law' was passed which provided the means of removing Jewish teachers from the universities, and of course also to remove those of Jewish descent from other roles. On 25 April 1933 a Law against 'Overcrowding in German Schools and Universities' was passed under which children who were not of Aryan descent (having one grandparent of the Jewish religion made someone non-Aryan) were to be banned from attending secondary school but there were exemptions for those whose parents had fought for Germany in World War I. Because Siegfried Ursell had served during World War I, Fritz was allowed to begin his secondary education at the Comenius Gymnasium. This school, founded in 1908, had originally been known as the "High School for Boys in Upper Cassel".

At the Comenius Gymnasium, Fritz learnt Greek and Latin. It provided a good classical education but the mathematics teaching was poor and Fritz had little interest in this topic. His years at the Gymnasium grew increasingly more difficult with discrimination against Jews becoming ever more severe. By 1936 he was the only Jewish child left at the Gymnasium and his parents realised that they had to act quickly to give him a chance in life, or even the chance of a life. Fritz's mother Leonore had a cousin working as a doctor in London and a friend Jeannette Franklin-Kohn who had left Düsseldorf for England where she had set up an organisation in Bournemouth to help Jewish German children escape from the Nazis. Franklin-Kohn arranged for Fritz to enter Streete Court School, a Preparatory School in Westgate-on-Sea, Kent. He began his studies there in January 1937 and quickly mastered English so, by June of that year, he was able to sit the Common Entrance Examination into Clifton College, Bristol.

Ursell did well at Clifton College partly, he believed, because of his good grounding in Latin gained in Düsseldorf. He performed well in the examination in December 1938 but, if he was to remain at school, he had to specialise at this stage. If he left school, Ursell would have had to return to Germany where his parents were still living. H C Beaven, the Head of Mathematics at Clifton College, advised Ursell's parents to let their son specialise in mathematics since he felt that in this subject Ursell would have a good chance of a university scholarship. Beaven, a Balliol graduate known as "Fuzzy B", was described at his funeral in 1939 as a "devoted and unselfish scholar whose whole being becomes part of the school they serve". Ursell's parents did not like the idea that their son would study a "useless" subject like mathematics but, nevertheless, they reluctantly agreed to let him follow Beaven's advice. At least, they thought, studying mathematics would not be as bad as having their son return to Nazi Germany. Ursell entered the Upper Fifth Mathematics class at Clifton College in January 1939.

The position of Jews in Germany in 1939 was dire. Ursell's father was no longer allowed to practice as a doctor. The family applied for American visas but while they were waiting, their situation was so difficult that they managed to get permission to come to England to wait until the visa applications came through. However, they never made it to the United States. They were still waiting in England when, on 1 September 1939, Germany invaded Poland. Two days later Britain was at war with Germany and the whole Ursell family were enemy aliens. Fritz was doing well at Clifton College where he was studying mathematics, physics, English, Old Testament and German. Rather surprisingly, given the topics on which he would later undertake research, the one subject he disliked was physics. For some months the war seemed to be rather remote to those living in England except for government preparations like moving children out of cities in February 1940. However, in May 1940 German troops invaded Holland and Belgium, taking Boulogne before the end of the month. Fritz Ursell was told that, as an enemy alien, he could not remain in Bristol since enemy aliens could not live within 50 miles of the coast. This might have ended his hopes of taking the Cambridge scholarship examinations later that year but the headmaster of Clifton College, Bertrand Leslie Hallward (1901-2003), managed to arrange for him to study at Marlborough College, a famous boys' school in the small town of Marlborough in Wiltshire. The police gave permission for him to study there. We note that, after Ursell left Clifton College, on 2 December 1940 bombs hit the school buildings and Clifton College was evacuated to Bude on the Cornish coast. The Head of Mathematics at Marlborough College was the excellent teacher Alan Robson and, guided by him, Ursell gained a distinction in the School Certificate examinations. He wrote [1]:-

The teaching of mathematics at Marlborough was of high quality, ranked second in England after Winchester College, the famous fourteenth century foundation. The head of mathematics was Mr Alan Robson, a wonderful mathematician. I was at Marlborough from May to December, and I learnt a great deal. By December I was in a stronger position than if I had stayed at Clifton.

Following Robson's advice he took the examinations for a scholarship at Trinity College, Cambridge. Knowing that he had no financial support, but that he had produced an outstanding performance (particularly in projective geometry) in the Cambridge Scholarship Examinations in December, the University augmented the Trinity Scholarship he won to enable him to cover the whole cost of his studies.

In January 1941, Ursell matriculated at Trinity College Cambridge. His Director of Studies was Abram Samoilovitch Besicovitch. He performed well in the Mathematical Tripos and, after obtaining permission to delay war work and take Part III, he began to take that course in October 1942. Only five students were in Ursell's class at this stage, and they included Freeman Dyson and James Lighthill. Ursell, feeling that the other students were much better than he was, approached Besicovitch with his worries. Besicovitch said [2]:-

You will never have to compete, these talented people will not be interested in your problems but in different problems. Also, they may abandon mathematics altogether, like the famous Trinity mathematician Isaac Newton. And finally, it is not the good mathematicians who do the good mathematics.

After taking courses by G H Hardy on divergent series, J E Littlewood on complex analysis, A E Ingham on number theory, W V D Hodge on Riemann surfaces, and P A M Dirac on quantum mechanics, Ursell graduated with distinction in 1943.

Having already delayed undertaking war work in order to complete Part III, Ursell was now keen to make his contribution to the war effort. He was recommended for work at the Royal Aircraft Establishment at Farnborough but they refused to accept an enemy alien. He was then sent to the Admiralty Research Laboratory at Teddington in southwest London. In May 1944 he joined the Wave Group and this was to determine the topics that he would continue to undertake research in for the rest of his life. He became a leading expert in the mathematical modelling of waves. The work done by the Wave Group made a major contribution to the war effort for their data was used to set the strategy for the Allied landings in Normandy and in the Pacific.

Ursell published a joint paper with Norman Frederick Barber, The Generation and Propagation of Ocean Waves and Swell. I. Wave Periods and Velocities in 1948. It appeared in the Philosophical Transactions of the Royal Society of London and was submitted in May 1947 by the authors who were both working at the Admiralty Research Laboratory. Here is the authors own summary:-

A method is described for measuring and examining ocean waves in a way which allows their amplitude and period to be determined with some precision. Data obtained in this way are compared with meteorological charts of the ocean in an attempt to assess the velocity of propagation of swell over long distances. A critical estimate is only possible when the meteorological conditions are sufficiently simple, but in one selected example it appears that the velocity of propagation is within 5% of the value prescribed by hydrodynamical theory. The evidence in more complicated instances does not disagree with this result, but does not permit of such an exact interpretation. The waves are measured by the fluctuating pressure which they produce upon an instrument laid on the sea bed in shallow water near the coast. The resulting curves are examined by a machine which draws the frequency spectrum of the recorded waves. The information given by these spectra is combined with the information of wind strength given by the meteorological charts to form a 'propagation diagram' whose appearance is a test of the validity of the theoretical group velocity. A suitable theoretical basis is given to the work.

We note that Norman Barber played an important role in Ursell's development. He writes [8]:-

[Norman Barber] was a true physicist, with physical insights which (as I then discovered) differ greatly from mathematical insights. ة Of all my colleagues he had the most profound influence on me. For me he was the closest approximation to a thesis supervisor, for I never was a graduate student. We remained in touch until his death in 1992.

In September 1947 Ursell left the Admiralty Research Laboratory and, having been awarded an Imperial Chemical Industries 3-year research fellowship, joined the Department of Applied Mathematics at the University of Manchester. The fellowship, although funded by Imperial Chemical Industries, allowed Ursell to undertake research in any area and he had no commitment to ICI. Before the award of the fellowship he had submitted a thesis to Trinity College, Cambridge for a Fellowship and, shortly after moving to Manchester, he was informed that he had been awarded a 4-year Prize Fellowship by Trinity College, Cambridge. Ursell asked Trinity if he could have leave of absence and was allowed to spend the three years at Manchester before taking up the Trinity Fellowship. Ursell's parents and sister continued to live in Cambridge but his father died on 4 December 1947 at the age 68. Ursell wrote three important papers while at Manchester, namely Surface waves on deep water in the presence of a submerged circular cylinder. I and II (1950), and Trapping modes in the theory of surface waves (1951).

In 1950 Ursell returned to Cambridge where, in addition to his Trinity Fellowship, he was appointed to a University Lectureship in Applied Mathematics. He moved in with his mother and sister who were living at 4 Belvoir Terrace, Trumpington Road, Cambridge. A visit to the United States in 1951 was important, for at this time he made contact with, among other, Richard Courant and Kurt Friedrichs in New York, and Garrett Birkhoff at Harvard. He arrived in New York on 15 August 1951 having sailed from Southampton on the ship America. He also spent the academic year 1957-58 in America, at the Massachusetts Institute of Technology in Cambridge, Massachusetts. In New York he had met Katharina Renate Braude (known as Renate), whose maiden name was Zander. They were married in Cambridge, England, on 19 June 1959, and had two daughters, Ruth and Susie.

In 1961 Ursell was offered the Beyer Chair of Applied Mathematics at the University of Manchester. The chair had become vacant when James Lighthill had left Manchester to become director of the Royal Aircraft Establishment at Farnborough. However, this was no easy decision for Ursell since he was unsure whether he wanted to take on the administrative work involved in such a position. Another complication was that the Massachusetts Institute of Technology also offered him a professorship at this time. After lengthy deliberations he accepted the Manchester position and he remained there for the rest of his career.

We have already said a little about Ursell's mathematical contributions, but at this point we quote David Abrahams and Paul Martin [7]:-

Fritz made seminal contributions to research in the mathematical analysis of linear water waves. This required the development of new techniques for the asymptotic evaluation of integrals, especially uniformly valid approximations. He made numerous contributions to the field, for example, he constructed a family of solutions for edge waves on a sloping beach, extending Stokes' original result; he gave a detailed analysis of the Kelvin ship wave patter; and he was the first to prove the existence of trapped modes in water-wave problems, here for the case of a submerged circular cylinder. His papers, collected and published by World Scientific in 1994, are exceptional for their clarity and precision.

Ursell was honoured by being elected to the Royal Society of London in 1972. When he retired from the University of Manchester in 1990, a two-day conference was held in his honour. He gave the final talk at the conference, namely Some unsolved and unfinished problems in the theory of waves. When he reached the age of 85 in 2008, the University of Manchester held another conference in his honour. In a talk he gave at this meeting, he continued to give his thoughts on the direction that universities were taking [2]:-

Fritz was an active participant in university politics, fearful of the progressive intrusion of market and business ideology into the ethos of university life. He strove valiantly to oppose the transition from a collegial to a management style of university government, although he recognized that it was a losing battle. In his 2008 lecture, Fritz warned that 'recent university reforms ة have increased the control of government over the research done in universities'. He was tireless in drawing attention to the negative impact of these changes, in speeches to university bodies and in letters to university administrators.

As to Ursell's character, we quote from David Evans, one of his students [3]:-

His lectures, just like his research papers were models of clarity and precision, but again, like his papers, they contained a depth of detail only revealed on closer study. ... As a junior colleague I was very much in awe of him because of his reputation and position and it was many years later before I plucked up the courage to address him as Fritz. In fact I needn't have worried. He was a kind and gentle man, not one to stand on ceremony and wholly supportive of his former students, myself included, throughout their careers. Aside from his consummate skills as a mathematician, Fritz was a true renaissance man, capable of conversing knowledgeably yet modestly, on a wide range of subjects including European history, politics, music, and literature, especially Shakespeare.

Books:

1. M S Schmid, First Language Attrition, Use and Maintenance: The Case of German Jews in Anglophone Countries (John Benjamins Publishing, 2002).

Articles:

1. I D Abrahams and P A Martin, Fritz Joseph Ursell. 28 April 1923 -11 May 2012, Biographical Memoirs of Fellows of the Royal Society 59 (2013), 407-421.
2. D Evans, Fritz Joseph Ursell 1923-2012, in Bernard Molin, Olivier Kimmoun, Fabien Remy (eds.), Proceedings 28th International Workshop on Water Waves and Floating Bodies (2014), ix-xi.
3. In Memoriam - Fritz Joseph Ursell. 28 April 1923-11 May 2012, School of Mathematics, University of Manchester, Newsletter (Summer 2013), 16-17.
4. Obituary - Fritz Joseph Ursell, The Times (15 May, 2012).
5. Professor Fritz Ursell, The Telegraph (12 July 2012).
6. Professor Fritz Ursell, born April 28 1923, died May 12 2012, London Math. Soc. Newsletter (12 July 2012).
7. F Ursell, Reminiscences of the early days of the spectrum of ocean waves, in S G Sajjadi, N H Thomas and J C R Hunt (eds.), Wind-over-wave couplings. Perspectives and prospects (Oxford University Press, Oxford, 1999), 127-137.