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Sydney Chapman
Times obituary
An outstanding mathematical physicist
Professor Sydney Chapman, F.R.S., who died on Tuesday at the age of 82, was both a legend and a scientist. Up to his retirement from Oxford in 1953, he had made contributions of the first magnitude to each of stellar dynamics, terrestrial magnetism (which he renamed geomagnetism), meteorology, and the kinetic theory of gases. Widely honoured and frequently consulted, he was an inevitable choice in that year as president of the Commission for the International Geophysical Year. At the same time, he took up new scientific posts at the High Altitude Observatory, Boulder, Colorado, and at the Geophysical Institute of Alaska, where he had already been advisory scientific director for two years.
For more than 15 years after reaching retiring age, he remained as active and interested as ever. He was younger in spirit and pleasure than many 20 or even 25 years of his junior. At 80, he delighted in getting through as much or more in a day as he had ever done. And he frankly enjoyed not only work but also world recognition, the rewards that came with it, and the many stories told of him.
He was born at Eccles in Lancashire on January 29, 1888, and educated at elementary and technical schools and took an engineering degree in Manchester in 1907. His interests turned to mathematics, and after graduating in this subject at Manchester in 1908, he proceeded to Trinity College, Cambridge. He became a wrangler, having sat the mathematical tripos in his second year, and began his research in pure mathematics under G. H. Hardy. He might have continued in this field but for the intervention of Sir Frank Dyson Astronomer Royal, who offered him the post of Chief Assistant at Greenwich, a post which he held from 1910 until 1914, when he returned to Cambridge as a lecturer in mathematics. He was awarded the first Smith's Prize in 1913, and in the same year was elected to a fellowship at Trinity College, which he held until 1919. In that same year he was elected a Fellow of the Royal Society. He held professorships at Manchester (1919-24), Imperial College, London (1924-46), and Oxford (1946-53). He was Deputy Scientific Advisor to the Army Council from 1943 to 1945.
In geomagnetism, he extended the work of Moos on the average characteristics of magnetic storms and showed that they could be divided into two distinct phases. The first, which is characterized by an increase in the horizontal force for a period of a few hours, the second, or main phase, by a larger and more prolonged decrease lasting several hours, taking up a suggestion by F. A. Lindemann, later Lord Cherwell, that magnetic storms and aurorae are caused by the interaction of a neutral but ionized solar corpuscular stream with the Earth's magnetic field. Chapman, with one of his pupils, developed in 1930 a theory of magnetic storms in which their sudden commencement and first phase were ascribed to the compressions of the tubes of force of the magnetic field by the first onrush of the stream.
In seeking an explanation of the Earth's magnetic field in periods of a lunar day and its submultiples, Chapman found that part of the origin must be sought in the atmosphere. He succeeded in tracing this to its source. The moon must produce a small tide in the atmosphere, and the atmosphere contains charged particles. The tidal current carrying these would produce the kind of change in the magnetic field required, provided the atmospheric tide was large enough. The expected changes in pressure would be only of the order of that of a foot of air or 0.03 mm of mercury. Through a discussion of an enormous number of observations, Chapman succeeded in tracing it. The analysis was carried out for many meteorological stations, but apart from its original application, the results are of first importance to the study of atmospheric motions.
Chapman's other major contribution was to the kinetic theory of gases, which, until he began his research in 1911, was much in the same state as Maxwell and Boltzmann had left it, apart from an attempt by Lorentz in 1905 toward an accurate theory of a non-uniform gas. In 1916, Chapman published a memoir in which he was able to complete the theory of non-uniform gases as well as to give exact formulas for the various transport coefficients for a simple gas. In 1917, he extended this work to a gas mixture and predicted the phenomenon of thermal diffusion, the prediction of which, unknown to Chapman, had been made by Enskog in 1911. The reality of this phenomenon was demonstrated experimentally by Dootson in 1916, and it has since found important technical applications.
Chapman was awarded the Adams Prize for an essay in geomagnetism in 1929. This was later expanded into a book, Geomagnetism, written in collaboration with J. Bartels. In 1939, he likewise collected his wonk on gases in a book written with T. G. Cowling entitled The Mathematical Theory of Non-Uniform Gases.
It would be difficult to overestimate the great influence which Chapman exerted on the scientific world at large. His counsel was widely sought, and he was an acquainted authority on many scientific subjects. It was inevitable that, at its inception, Chapman should have been elected president of the Commission for the International Geophysical Year. He also served as president of the International Association for Meteorology (1936-48), Terrestrial Magnetism and Electricity (1948-51), and of the International Union for Geodesy and Geophysics from 1941-54, and of several learned societies, the London Mathematical, Royal Meteorological, Royal Astronomical and Physical Society.
He was elected to the United States, Indian, Norwegian, Swedish, and Finnish National Academies of Science, and to the Academies of Halle and Göttingen. He was made an honorary Fellow of Queen's College, Oxford (1954), of Imperial College (1956), and his own college, Trinity, similarly honoured him in 1957. The Universities of Cambridge, Alaska, and Michigan conferred honorary degrees on him. His great capacity for work enabled him, upon his retirement from Oxford in 1953, to take up scientific posts at the High Altitude Observatory, Boulder, Colorado, and at the Geophysical Institute of Alaska, where he had been Advisory Scientific Director since 1951.
Chapman's mild manner veiled a strong will and great determination; his tastes and habits were simple. He was an enthusiastic cyclist, swimmer, and walker, and both on his visits to foreign universities and to international conferences, however varied the available modes of transport might be, Chapman could always be relied upon to arrive on a bicycle. He rode from Montreal to Washington in 1939 to attend the meeting of the International Geophysical Union.
He married in 1922, Katharine Nora, daughter of the late A. E. Steinthal, of Manchester, and they had three sons and a daughter.
An outstanding mathematical physicist
Professor Sydney Chapman, F.R.S., who died on Tuesday at the age of 82, was both a legend and a scientist. Up to his retirement from Oxford in 1953, he had made contributions of the first magnitude to each of stellar dynamics, terrestrial magnetism (which he renamed geomagnetism), meteorology, and the kinetic theory of gases. Widely honoured and frequently consulted, he was an inevitable choice in that year as president of the Commission for the International Geophysical Year. At the same time, he took up new scientific posts at the High Altitude Observatory, Boulder, Colorado, and at the Geophysical Institute of Alaska, where he had already been advisory scientific director for two years.
For more than 15 years after reaching retiring age, he remained as active and interested as ever. He was younger in spirit and pleasure than many 20 or even 25 years of his junior. At 80, he delighted in getting through as much or more in a day as he had ever done. And he frankly enjoyed not only work but also world recognition, the rewards that came with it, and the many stories told of him.
He was born at Eccles in Lancashire on January 29, 1888, and educated at elementary and technical schools and took an engineering degree in Manchester in 1907. His interests turned to mathematics, and after graduating in this subject at Manchester in 1908, he proceeded to Trinity College, Cambridge. He became a wrangler, having sat the mathematical tripos in his second year, and began his research in pure mathematics under G. H. Hardy. He might have continued in this field but for the intervention of Sir Frank Dyson Astronomer Royal, who offered him the post of Chief Assistant at Greenwich, a post which he held from 1910 until 1914, when he returned to Cambridge as a lecturer in mathematics. He was awarded the first Smith's Prize in 1913, and in the same year was elected to a fellowship at Trinity College, which he held until 1919. In that same year he was elected a Fellow of the Royal Society. He held professorships at Manchester (1919-24), Imperial College, London (1924-46), and Oxford (1946-53). He was Deputy Scientific Advisor to the Army Council from 1943 to 1945.
In geomagnetism, he extended the work of Moos on the average characteristics of magnetic storms and showed that they could be divided into two distinct phases. The first, which is characterized by an increase in the horizontal force for a period of a few hours, the second, or main phase, by a larger and more prolonged decrease lasting several hours, taking up a suggestion by F. A. Lindemann, later Lord Cherwell, that magnetic storms and aurorae are caused by the interaction of a neutral but ionized solar corpuscular stream with the Earth's magnetic field. Chapman, with one of his pupils, developed in 1930 a theory of magnetic storms in which their sudden commencement and first phase were ascribed to the compressions of the tubes of force of the magnetic field by the first onrush of the stream.
In seeking an explanation of the Earth's magnetic field in periods of a lunar day and its submultiples, Chapman found that part of the origin must be sought in the atmosphere. He succeeded in tracing this to its source. The moon must produce a small tide in the atmosphere, and the atmosphere contains charged particles. The tidal current carrying these would produce the kind of change in the magnetic field required, provided the atmospheric tide was large enough. The expected changes in pressure would be only of the order of that of a foot of air or 0.03 mm of mercury. Through a discussion of an enormous number of observations, Chapman succeeded in tracing it. The analysis was carried out for many meteorological stations, but apart from its original application, the results are of first importance to the study of atmospheric motions.
Chapman's other major contribution was to the kinetic theory of gases, which, until he began his research in 1911, was much in the same state as Maxwell and Boltzmann had left it, apart from an attempt by Lorentz in 1905 toward an accurate theory of a non-uniform gas. In 1916, Chapman published a memoir in which he was able to complete the theory of non-uniform gases as well as to give exact formulas for the various transport coefficients for a simple gas. In 1917, he extended this work to a gas mixture and predicted the phenomenon of thermal diffusion, the prediction of which, unknown to Chapman, had been made by Enskog in 1911. The reality of this phenomenon was demonstrated experimentally by Dootson in 1916, and it has since found important technical applications.
Chapman was awarded the Adams Prize for an essay in geomagnetism in 1929. This was later expanded into a book, Geomagnetism, written in collaboration with J. Bartels. In 1939, he likewise collected his wonk on gases in a book written with T. G. Cowling entitled The Mathematical Theory of Non-Uniform Gases.
It would be difficult to overestimate the great influence which Chapman exerted on the scientific world at large. His counsel was widely sought, and he was an acquainted authority on many scientific subjects. It was inevitable that, at its inception, Chapman should have been elected president of the Commission for the International Geophysical Year. He also served as president of the International Association for Meteorology (1936-48), Terrestrial Magnetism and Electricity (1948-51), and of the International Union for Geodesy and Geophysics from 1941-54, and of several learned societies, the London Mathematical, Royal Meteorological, Royal Astronomical and Physical Society.
He was elected to the United States, Indian, Norwegian, Swedish, and Finnish National Academies of Science, and to the Academies of Halle and Göttingen. He was made an honorary Fellow of Queen's College, Oxford (1954), of Imperial College (1956), and his own college, Trinity, similarly honoured him in 1957. The Universities of Cambridge, Alaska, and Michigan conferred honorary degrees on him. His great capacity for work enabled him, upon his retirement from Oxford in 1953, to take up scientific posts at the High Altitude Observatory, Boulder, Colorado, and at the Geophysical Institute of Alaska, where he had been Advisory Scientific Director since 1951.
Chapman's mild manner veiled a strong will and great determination; his tastes and habits were simple. He was an enthusiastic cyclist, swimmer, and walker, and both on his visits to foreign universities and to international conferences, however varied the available modes of transport might be, Chapman could always be relied upon to arrive on a bicycle. He rode from Montreal to Washington in 1939 to attend the meeting of the International Geophysical Union.
He married in 1922, Katharine Nora, daughter of the late A. E. Steinthal, of Manchester, and they had three sons and a daughter.
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