Plummer, Henry Crozier

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(b. Oxford, England, 24 October 1875; d. Oxford, 30 September 1946)


The son of an astronomer, Plummer graduated from Hertford College, Oxford, with first class honors and in 1901 became an assistant at the Oxford University Observatory. He is known primarily for his book Dynamical Astronomy (1918), which is still used as a text and reference in theoretical and practical celestial mechanics and is valued for both its content and its style. In addition to dynamics, Plummer was interested in the accuracy of measurements, the theory of errors, and in mathematical methods applied to astronomical computations. During his lifetime he worked on many topics, including the Astrographic Chart and Catalogue, cometary motion (including nongravitational forces), stellar motions, spectroscopic binaries, and the dynamics of globular star clusters.

In 1912 Plummer was appointed astronomer royal of Ireland, a post once occupied by William Hamilton. It is said that Plummer wanted to concentrate on observational astronomy but that the Irish climate frustrated him and enforced a preoccupation with theoretical topics. His isolation and the quality of instruments at the Dunsink Observatory (there had been no new equipment since the 1860’s) increased his dissatisfaction. In 1921 he resigned from this post and became professor of mathematics at the Royal Artillery College, where he remained until his retirement in 1940. Plummer was elected a fellow of the Royal Society (1920) and was president of the Royal Astronomical Society (1939).

In addition to his many research papers and Dynamical Astronomy, Plummer wrote two other books: Principles of Mechanics (1929) and Probability and Frequency (1939). He was preparing an edition of Newton’s works at the time of his death.

Although his contemporaries made greater innovations, Plummer did not lack originality and he was a superb expositor.


Plummer wrote more than 100 scientific papers, most of which appeared in Monthly Notices of the Royal Astronomical Society, His textbooks are Introductory Treatise on Dynamical Astronomy (Cambridge, 1918); Principles of Mechanics (London, 1929); and Probability and Frequency (London, 1939).

On Plummer and his work, see W. M. H. Greaves’s notice in Dictionary of National Biography, 1941–1950 (1959), 667–668; Obituary Notices of Fellows of the Royal Society, no. 16 (May 1948); W. M. Smart, in Monthly Notices of the Royal Astronomical Society, 56 (1947), 107; and Edmund Whittaker, in Observatory, 66 (1946), 394.

J. M. A. Danby