Ralph Allen Sampson

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25 June 1866
Schull, Co Cork, Ireland
7 November 1939
Bath, England

Ralph Sampson was an Irish astronomer who worked on the theory of the motions of Jupiter's four Galilean satellites.


Ralph Sampson's father was James Sampson, a metallurgical chemist from Cornwall, and his mother was Sarah Anne Macdermott, from Ireland. Ralph was the fourth of his parents' five children and was born in Schull, County Cork, Ireland, where his father was working at the time. When he was five years old the family moved to Liverpool but his father became ill, perhaps brought on by financial worries when his investments in Cornish tin mines failed and he could not afford to educate his children. After two years of illness James Sampson died and his family continued to struggle financially.

Only at age fourteen did Ralph's formal education begin when he entered the Liverpool Institute. He showed remarkable abilities and was awarded a scholarship to St John's College, Cambridge to study mathematics. Entering Cambridge in June 1884, he studied the Mathematical Tripos, was tutored by John Couch Adams, and was third Wrangler in the Tripos of 1888. Following this he was appointed as a lecturer in mathematics at King's College, London. In 1889 he was awarded the first Smith's prize by Cambridge and elected a fellow of St John's College in November 1890. After two years as a lecturer in mathematics in London, Sampson returned to Cambridge in 1891 when he became the first holder of the Isaac Newton Studentship in Astronomy and Physical Optics. During his time in London he had published On Stokes' Current-Function [2]:-
This is a hydrodynamical investigation relating to irrotational motion, symmetric about an axis, in a liquid, the velocity-potential being expressible as a sum of solid zonal harmonics.
He worked for the two years 1891-93 in Cambridge on astronomical spectroscopy and published a major paper On the rotation and mechanical state of the Sun [2]:-
In addition to the usual assumption that the angular velocity increases inwards along all radii, he laid down postulates for a new theory of the distribution of the sun's internal temperature; being somewhat dissatisfied with the theory of convective equilibrium, he laid stress on the effects of radiation and absorption.
In 1893 he was appointed as Professor of Mathematics at Durham College in Newcastle-upon-Tyne. He married Ida Binney, daughter of H A Binney of St Helens, in 1894; they had three daughters and a son. Although Sampson had been brought up as an Anglican, his wife belonged to the Society of Friends. He joined and soon became a prominent member in the Durham area. In 1895 he was appointed Professor of Mathematics at Durham. He also became Director of the Durham Observatory [1]:-
It was in Durham that Sampson undertook his greatest work, the dynamical theory of the four largest satellites of Jupiter. At that time, there were serious discrepancies between the theoretical predictions and actual observations of the four satellites. Sampson used a series of accurate observations from Harvard College Observatory to amend the existing theory of the satellite orbits, but the disagreement between theory and observation persisted. He worked out a new dynamical theory and published in 1910 Tables of the Four Great Satellites of Jupiter, giving positions of the satellites from 1850 to 2000. His 'Theory of the Four Great Satellites of Jupiter' appeared in 1921 and earned him the Gold Medal of the Royal Astronomical Society. He did pioneering work in measuring the colour temperature of stars.
Sampson also did a superb job editing one volume of the papers of his former tutor, John Couch Adams. The whole work was published in several volumes between 1896 and 1900, with Sampson's volume appearing in 1900. This was the hardest of the volumes to edit since it consisted of Adams unpublished manuscripts. To study the manuscripts, he lived at Cambridge for a time while he undertook the difficult task. He explained:-
The papers as they reached me, and indeed as Adams left them, were almost devoid of arrangement, except that they were folded in parcels of a few pages each, the product of a day's or a few days' sitting: each parcel was generally very clear in itself, but carried no indication of its purpose or relations to others.
His election as a Fellow of the Royal Society in 1903 was partly as a result of editing Adams's papers.

In 1910 Sampson was appointed to a professorship at the University of Edinburgh and also as Astronomer Royal for Scotland. Whittaker writes [2]:-
As Director of the Royal Observatory on the Blackford Hill he devoted much attention to the determination and recording of time, especially as regards the behaviour of observatory clocks ... He was elected as the first President of the "Commission de I'Heure" but resigned from this later owing to differences with the French astronomer Bigourdan. He also published many papers on the geometrical optics of telescopes and the methods of removing optical defects ...
In 1915 he was awarded the Hopkins Prize of the Cambridge Philosophical Society, and was elected President of the Royal Astronomical Society. He served as President until 1917, having Arthur Eddington as Secretary of the Society during these two years. Of course, his period of office fell exactly in the middle of World War I and this produced some difficulties since many fellows were on military service and unable to pay their subscriptions. An additional bye-law was passed excusing those on military service from paying subscriptions until the end of the year following that in which peace was declared. More significant was that during Sampson's presidency, women were admitted as fellows on equal terms to men. The necessary action was taken at the Annual General Meeting of 1915, and the first women fellows were elected at the meeting in January 1916.

Sampson received many honours for his contributions. We have mentioned several of these above, but let us also mention that he was elected a fellow of the Royal Society of Edinburgh on 4 December 1911 being proposed by Sir Frank Watson Dyson, Sir James Walker, Arthur Robinson, and James Gordon MacGregor. He served the Society as Councillor 1912-15 and 1919-21, as Vice-President 1915-18 and 1933-36, as Secretary to Ordinary Meetings 1922-23, and as General Secretary 1923-33. The Society also honoured him with the award of their Keith Prize 1919-21. The University of Durham conferred on him the honorary degree of D.Sc., and the University of Glasgow that of LL.D.

Sampson retired from his positions at Edinburgh University at age 71 in 1937 due to failing health. He moved with his wife to Bath where he spent the last two years of his life.

References (show)

  1. Ian Elliott, Ralph Allen Sampson, in Thomas Hockey (ed.) Biographical Encyclopedia of Astronomers (2007), 1009-1011.
  2. E T Whittaker, Ralph Allen Sampson 1866-1939, Obituary Notices of Fellows of the Royal Society 3 (8) (1940), 220-226.

Additional Resources (show)

Other websites about Ralph Sampson:

  1. zbMATH entry
  2. ERAM Jahrbuch entry

Honours (show)

Cross-references (show)

Written by J J O'Connor and E F Robertson
Last Update July 2008