Sir Harold Jeffreys, FRS (22 April 1891 – 18 March 1989) was a British geophysicist who made significant contributions to mathematics and statistics. His book, Theory of Probability, which was first published in 1939, played an important role in the revival of the objective Bayesian view of probability.
Education Jeffreys was born in Fatfield, County Durham, England, the son of Robert Hal Jeffreys, headmaster of Fatfield Church School, and his wife, Elizabeth Mary Sharpe, a school teacher. He was educated at his father's school and at Rutherford Technical College, then studied at Armstrong College in Newcastle upon Tyne (at that time part of the University of Durham) and with the University of London External Programme. Jeffreys subsequently won a scholarship to study the Mathematical Tripos at St John's College, Cambridge, where he established a reputation as an excellent student: obtaining first-class marks for his papers in Part One of the Tripos, he was a Wrangler in Part Two, and in 1915 he was awarded the prestigious Smith's Prize.
Career Jeffreys became a fellow of St John's College in 1914, retaining his fellowship until his death 75 years later. At the University of Cambridge he taught mathematics, then geophysics and finally became the Plumian Professor of Astronomy. In 6 September 1940, he married fellow mathematician and physicist, Bertha Swirles (1903–1999), and together they wrote Methods of Mathematical Physics. One of his major contributions was on the Bayesian approach to probability (also see Jeffreys prior), as well as the idea that the Earth's planetary core was liquid. By 1924 Jeffreys had developed a general method of approximating solutions to linear, second-order differential equations, including the Schrödinger equation. Although the Schrödinger equation was developed two years later, Wentzel, Kramers, and Brillouin were apparently unaware of this earlier work, so Jeffreys is often neglected when credit is given for the WKB approximation. Jeffreys received the Gold Medal of the Royal Astronomical Society in 1937, the Royal Society's Copley Medal in 1960, and the Royal Statistical Society's Guy Medal in Gold in 1962. In 1948, he received the Charles Lagrange Prize from the Académie royale des Sciences, des Lettres et des Beaux-Arts de Belgique. He was knighted in 1953. From 1939 to 1952 he was established as Director of the International Seismological Summary further known as International Seismological Centre. The textbook Probability Theory: The Logic of Science, written by the physicist and probability theorist Edwin T. Jaynes, is dedicated to Jeffreys. The dedication reads, "Dedicated to the memory of Sir Harold Jeffreys, who saw the truth and preserved it." An appendix to the third edition of Jeffreys' book Scientific Inference explains Mary Cartwright's method of proving that the number π is irrational.
Opposition to continental drift and plate tectonics Jeffreys, like many of his peers, staunchly opposed the concept of continental drift as put forth by Alfred Wegener and Arthur Holmes. This opposition persisted even into the 1960s among his colleagues at Cambridge. For him, continental drift was "out of the question" because no force even remotely strong enough to move the continents across the Earth's surface was evident. As geological and geophysical evidence for continental drift and plate tectonics mounted in the 1960s and after, to the point where it became the unifying concept of modern geology, Jeffreys remained a stubborn opponent of the theory to his death.
Honours and awards Fellow, Royal Society, 1925 Adams Prize, 1927 (Constitution of the Earth) Gold Medal, Royal Astronomical Society, 1937 Buchan Prize, Royal Meteorological Society, 1929 Murchison Medal of Geological Society (Great Britain) 1939 Victoria Medal, Royal Geographical Society, 1941 Charles Lagrange Prize, Brussels Academy, 1948 Royal Medal, 1948 William Bowie Medal, American Geophysical Union, 1952 Knighted, 1953 Copley Medal, Royal Society, 1961 Vetlesen Prize, 1962
Bibliography 1924: The Earth, Its Origin, History and Physical Constitution, Cambridge University Press; 5th edn. 1970; 6th edn. 1976 1927: Operational Methods in Mathematical Physics, Cambridge University Press via Internet Archive, Review: 1929: The Future of the Earth, Norton & Company 1931: Scientific Inference, Macmillan Publishers; 2nd edn. 1937; 3rd edn. 1973 1931: Cartesian Tensors. Cambridge University Press; 2nd edn. 1961 1934: Ocean Waves and Kindred Geophysical Phenomena, with Vaughan Cornish, Cambridge University Press 1935: Earthquakes and Mountains, Methuen Publishing; 2nd edn. 1950 1939: Theory of Probability, Clarendon Press, Oxford; 2nd edn. 1948; 3rd edn. 1961 1946: Methods of Mathematical Physics, with Bertha S. Jeffreys. Cambridge University Press; 2nd edn. 1950; 3rd edn. 1956; corrected 3rd edn. 1966 1962: Asymptotic Approximations, Clarendon Press, Oxford 1963: Nutation and Forced Motion of the Earth's Pole from the Data of Latitude Observations, Macmillan 1971–77: Collected Papers of Sir Harold Jeffreys on Geophysics and Other Sciences, Gordon and Breach
References
Further reading Aldrich, John (2005). "The Statistical Education of Harold Jeffreys". International Statistical Review. 73 (3): 289–308. Galavotti, Maria Carla (2003). "Harold Jeffreys' Probabilistic Epistemology: Between Logicism And Subjectivism". British Journal for the Philosophy of Science. 54 (1): 43–57. doi:10.1093/bjps/54.1.43. (A review of Jeffreys' approach to probability; includes remarks on R.A. Fisher, Frank P. Ramsey, and Bruno de Finetti. Howie, David (2002). Interpreting Probability: Controversies and Developments in the Early Twentieth Century. New York: Cambridge University Press. ISBN 0-521-81251-8. Swirles, Bertha (1992). "Reminiscences and Discoveries: Harold Jeffreys from 1891 to 1940". Notes Rec. R. Soc. Lond. 46 (2): 301–308. doi:10.1098/rsnr.1992.0028. JSTOR 531640. S2CID 144873990.
External links Works by or about Harold Jeffreys at the Internet Archive Photographs of Harold Jeffreys at Emilio Segrè Visual Archives, American Institute of Physics. Biography of Vetlesen Prize Winner – Sir Harold Jeffreys Harold Jeffreys as a Statistician
