Dr Herbert (Herby) Sixsmith, cryogenic engineer and Fellow of Wolfson College, died peacefully on 17 June in Vermont aged 93. He had become increasingly frail physically in recent years, and during his last few months was intermittently in hospital with heart problems.
Herby was educated at Kilkenny College, Kilkenny, Ireland and at Trinity College, Dublin, where he graduated with an honours degree in physics in 1940. Early in 1940 he joined the Admiralty Research Establishment working on the cavity magnetron at the University of Birmingham. This work was later moved to the British Thomson-Houston Company in Rugby.
After the war, Herby moved to the Cavendish Laboratory, Cambridge, where he continued work on the magnetron. In 1948 he was appointed lecturer in physics at Reading University. He commenced work on a vacuum tube scale-of-ten counter. This needed a high vacuum which at that time could be obtained only using a mercury vapour diffusion pump with a cold trap cooled by liquid air or liquid nitrogen. There was no supply of liquid air at the University. Whenever some was needed, it had to be obtained from Imperial College London. In response to a telephone call, someone would put a two-gallon container of liquid on to a train at Paddington, and someone from the University would meet the train at Reading and collect the container. There was a clear need for a generator of liquid air or nitrogen at the University. Conventional liquefiers at that time needed supply pressures in the range of 100 to 200 bar and an operator to keep them adjusted and running. Herby became fascinated with the possibilities of a reverse Brayton cycle with a turbine expander to provide the refrigeration. The pressure would be much lower (around 5 bar) and the compressor would therefore be simpler. To supply the needs of a small physics laboratory, the turbine would have to be small, with a rotor diameter of about 10 mm and a rotational speed of about 4000 revolutions per second. This was a challenge worth pursuing. Herby invented and developed a gas-lubricated bearing which would work reliably at these high speeds. When running, the relative velocity of the bearing surfaces is about 200 metres per second, the clearance is less than about 2.5 microns and the two surfaces never touch. There is no wear and no risk of contamination with oil. The turbine was incorporated in a small liquid air machine which ran unattended and produced about 5 litres per hour of liquid. Herby wrote his thesis on this machine and was awarded a PhD. The turbine was adopted and further developed by the British Oxygen Company and used in the LINIT liquid nitrogen generator.
In 1959, Herby joined the cryogenics division of the National Bureau of Standards at Boulder, Colorado, where he developed a small helium expansion turbine. One of his colleagues there, Vincent Arp, remembers that he obtained the use of an old lathe which he set up in an out-of-the-way location into which he would disappear and emerge some time later with components for his turbine, machined to a precision which the workshop had said was not possible. He was clearly gifted not only as an inventive designer but also as a skilled machinist.
In 1963, he moved to the Department of Engineering Science in Oxford, where he worked on a gas-bearing compressor for helium. When he retired (at the age of 67) in 1981, he found employment at Creare Inc., a small research and development company in Hanover, New Hampshire, USA, with a particular interest in cryogenics, where he worked on the development of miniature cryogenic machinery, used later for an application on the Hubble Space Telescope. On this, a critical instrument module, the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) uses cryogenically cooled detectors for deep space astronomical observations. The reservoir of solid nitrogen that provided the cooling became exhausted sooner than expected and signals from NICMOS came to an end.
In 1997 Creare undertook the construction of a reverse-Brayton cryocooler to restore the refrigeration. With miniature rotating machinery, the vibration is negligible. This is a major advantage since cryocooler vibration reduces the pointing accuracy of the telescope. The Creare cryocooler incorporated a miniature centrifugal compressor, a miniature turboexpander and a miniature circulator to transfer heat from the detectors to the cryocooler. It was designed, built and tested within fifteen months, and was flown in October 1998 on the space shuttle Discovery for testing. It was installed on the telescope in 2002.
Herby received international recognition for his contributions to cryogenics. He was given the J & E Hall Gold Medal by the Institution of Refrigeration in 1979, and the Samuel C Collins Award by the Cryogenic Society of America in 2001.
Herby was a well-liked and affable colleague and friend. He had a fund of Irish jokes, which if he had not been Irish himself would have been regarded as "non-PC". Walter Swift, his friend and colleague at Creare, tells me that during the last week of his life, he was in good spirits, and knew exactly what was going on, charming the nurses and physicians as you would expect. During this short time, he made at least 10 more good friends.
I think that this attitude epitomises the man - we shall all miss him.
He was cremated in Vermont, and his ashes will be brought back to Ireland.
Les Woods, as he always liked to be known, came to the Department of Engineering Science in 1961 as a University Demonstrator and Fellow of Balliol. A New Zealander, he was no stranger to Oxford, nor to University teaching. His undergraduate education at Auckland was interrupted by active service as a fighter pilot, but after completing degrees in both science and engineering he won a Rhodes Scholarship and came to Merton in 1948 to work for the DPhil in engineering.
Les was supervised by the Head of Department, Professor Thom, an aerodynamicist. Although he was surprised at, and critical of, the low status that he believed engineering had in Oxford, he liked Thom and respected his work. After only two years he successfully submitted his thesis on transonic flow around an aerofoil. He was unusual also in that he then went on to read for a BA in Mathematics, taking a first. On graduation in 1951 he was seconded to the National Physical Laboratory at Teddington by the New Zealand Scientific Defence Corps, but left in 1954 to take up a Senior Lecturership in Mathematics at Sydney, seeing that as a step towards returning to his native country. Two years later he was appointed to a research professorship at the new technological University of New South Wales. It was while on leave at Harwell in 1961 that he was asked by one of his former examiners if he would accept a demonstratorship in engineering with a Fellowship at Balliol. After some hesitation (for he also had tempting offers from Australia) he accepted, and began a long career in Oxford that would take him from engineering tutor to chairman of the Mathematical Institute.
When Professor Thom retired in 1961, Les Woods applied for the Headship and Chair - still the only one in the Department - but the post went to the distinguished experimentalist Douglas Holder from NPL. Naturally enough, given his background and his input to the Department, Les hoped for promotion; when it came, in 1965, it was to a Readership in Mathematics. He was able and willing to remain an engineering tutor, but could only do so with a reduced commitment, so he persuaded Balliol to elect a second Fellow in engineering. By 1969 he was appointed to a reconstituted professorship in theoretical plasma physics in the Mathematical Institute, which meant an end to tutoring. He had in the meantime expanded his interests from fluid mechanics to thermodynamics and nuclear fusion, so the chair fitted him well; he always wanted his mathematics to be relevant to the real world.
He continued to publish copiously, even after his retirement, and his unconventional views on fusion power made him an enfant terrible to those who worked in that area.
Les retained happy memories of his days as a tutor, and his pupils remembered him fondly. Naturally gregarious, he enjoyed social occasions, and even in his last years liked to meet undergraduates. Inclined to the left, he often castigated what he saw as the 'class system' of his adopted country, but he loved it, warts and all, and he had little time for cant, wherever it came from. His private life had its ups and downs; latterly, living on his own in his house on Boars Hill, he regarded Balliol as his second home and was often seen in College. He died at home, in his sleep, on 15 April 2007.
David Dew-Hughes came here as a University Lecturer and engineering tutor at University College in 1979, after the untimely death of Denis Campbell. He had read Metallurgy at Birmingham and then went to Yale to do a Doctorate, which was awarded in 1959. From 1958 to 1960 he worked on semiconductors in IBM's Research Laboratories in Poughkeepsie, NY, and then returned to England, where he took an academic post at the Department of Metallurgy at Cambridge. In 1965 he moved to the University of Lancaster, where he spent nine years, first as Senior Lecturer, then as Reader in the Physics of Materials.
During this period he co-authored with Oliver Wyatt a textbook Metals, Ceramics and Polymers: an Introduction to the Structure and Properties of Engineering Materials, which was published by Cambridge University Press in 1974. He then returned to the USA for another five years, spent in the Brookhaven National Laboratory, before coming to Oxford. Although his earliest research had been on semiconductors, superconductivity became a major interest from the 1960s, when they began to have practical applications. He had research groups on this at both Cambridge and Lancaster, which studied their metallurgical properties, including how they behaved when formed into the long thin conductors that were needed for magnets. He was co-editor with TS Luhman in 1979 of The Metallurgy of Superconducting Materials.
As well as a long list of publications to his credit, he sat on several learned-society committees and the editorial boards of their journals. When high-temperature superconductors were discovered, in the 1990s, he immediately started work on them, particularly their possible engineering applications, e.g. in large electric motors. He was a pioneer of inter-disciplinary research, and had set up collaborative projects with the Clarendon and the Department of Materials.
As a tutor at Univ, David was elected to teach the mechanical parts of the Engineering Science syllabus. It soon became evident, however, that he was no narrow specialist, and had a wide knowledge of both the electrical and mechanical sides of this ever-widening branch of learning. One interesting consequence of his appointment was that Richard, son of David's co-author Oliver Wyatt, came to the college to read engineering, even though his family had a very long tradition of sending their sons to Cambridge!
David, although normally a rather quiet man, did go in for some rather flamboyant waistcoats. And at the Encaenia Garden Party it was a pleasure to see him and his wife Denise both attired in their respective Doctoral robes, David's Oxford DSc robe being enhanced by a tassel representing an honorary degree from a European university.
He retired in 2000 and subsequently spent most of his time in the market town of Kirkby Lonsdale in Lancashire, where he had bought a house in his Lancaster days. He was a keen sailor, and also an enthusiast for old railways, especially in his native Wales, and in running and restoring old cars.
He died on 15 September 2006, and at his memorial service at Univ in February 2007 many friends and former colleagues testified to his companionability, sense of humour, and academic qualities. One of his former pupils, subsequently his research student, told how David had always tried to ensure that his pupils genuinely understood things, even when sometimes all they wanted to know was how to do the problems! This could be frustrating for them at the time, but very conducive to their intellectual development.
Gareth Roberts was born in Penmaenmawr, North Wales, and had a varied career in academia and industry. He graduated in physics at the University College of North Wales, did a PhD there and then a spell as lecturer. He worked for Xerox in the USA for a time before returning to the UK to the Universities first of Ulster and then of Durham. From 1985 to 1991 he combined research at Thorn EMI, eventually becoming director of research there, with a Visiting Professorship of Electronic Engineering at our Department in Oxford. Here he had a small group working on Langmuir-Blodgett films, in this case single-molecule surface layers of organic materials intended for use as sensors. He later became Vice-Chancellor of the University of Sheffield, and then returned to Oxford as President of Wolfson College. While at Sheffield he was also Chairman of the Committee of Vice-Chancellors and Principals, in which capacity he strongly resisted the funding cuts being imposed on the Universities by the Government. He was always a strong and energetic champion of scientific education, and was knighted in 1997 for services to higher education. He died of cancer in February 2007, aged only 66.
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