Robert Taylor Dunbar

Born: 8 February 1889 in Broughty Ferry, Angus, Scotland
Died: 1959 in Nottingham, England

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Robert Dunbar's father was Thomas S Dunbar (born Pitsligo, Aberdeenshire about 1852) who was a merchant tailor. His mother was Elizabeth Dunbar (born in Old Cumnock, Ayrshire about 1855). Robert Dunbar had eight older siblings: Isabella (born about 1876), Elizabeth (born about 1877), John (born about 1879), Marguerite (born about 1881), Mary (born about 1883), James (born about 1885), Thomas (born about 1886) and William (born about 1887).

Robert Dunbar entered the Eastern School, Broughty Ferry when he was five years old, moving to the Western School, Broughty Ferry after a year. After three years at this school e attended Grove Academy in Broughty Ferry, where he spent two years, then Harris Academy in Dundee where he spent seven years, the final two being at Central Classes, Harris Academy, Dundee.

He sat examinations in the Scottish Leaving Certificate in 1905 and 1906 and was awarded Higher passes in English, Mathematics, Latin, and Greek, with Lower passes in Dynamics, and French. He was awarded a bursary in 1907 to go to Edinburgh University. He first matriculated in 1907 and his course of study included Latin, Greek, Mathematics, Natural Philosophy, Intermediate Honours Mathematics, Thermodynamics, Intermediate Physics, Advanced Natural Philosophy, Advanced Mathematics, and Function Theory. In June 1915 he was awarded an M.A. with First Class Honours in Mathematics and Natural Philosophy. He was also awarded a B.Sc. (Pure) in the same year. Also in June 1915 he was awarded a Maclaren Mathematical Scholarship.

The dates above indicate that something is missing. Dunbar appears to have taken eight years from first matriculation to the award of his degree and this seems puzzling. The records at the University of Edinburgh show a gap between 1910 and 1914 when he took no courses. The only additional facts we can add to those given above are that Dunbar was awarded the Robert Wilson Memorial Prize for Chemistry from Edinburgh University for session 1910 and that he was runner-up for the Mackay-Smith scholarship in Natural Philosophy in 1910.

By the time Dunbar graduated in 1915, World War I was in progress. On 16 August 1915 Dunbar received his Commission Documents sent to Captain Robert Taylor Dunbar, Royal Garrison Artillery. At the end of the war Dunbar returned to Edinburgh University. He was appointed Assistant in Natural Philosophy in 1919 and worked for his doctorate supervised by Charles Glover Barkla. In 1921 he became a Lecturer in Natural Philosophy. In the same year he married Margaret Pirie White.

Margaret White was born in Edinburgh in 1892. She attended Torphican Public School from 1899 to 1903, James Gillespie's School from 1903 to 1904, then George Watson's Ladies' College from 1904 to 1911. She then attended Edinburgh University where she graduated M.A. with first class honours in mathematics and natural philosophy in June 1915. She was an assistant in natural philosophy at Edinburgh University from 1916 to 1920 and she was appointed lecturer in 1920. In the following year she resigned in order to marry Robert Dunbar. She published the paper Absorption and scattering of X-rays and the characteristic radiations of the J series in collaboration with Charles Glover Barkla. It appeared in the Philosophical Magazine (October 1917).

Robert Dunbar was awarded his doctorate in 1924. His wife was also awarded a doctorate. Dunbar left Edinburgh in 1924 to take up the position of Senior Lecturer in Physics at University College Cardiff. He was also Director of the Viriamu Jones Physics Research Laboratory at Cardiff. In 1930 he was promoted to Professor of Physics at University College, Cardiff, a position he held for the rest of his career.

The obituary of Charles Glover Barkla in the Royal Society in 1947 gives technical details of Robert Dunbar's contributions:-

The bearing of Compton's theory on the J-phenomena was investigated by R T Dunbar, an Edinburgh graduate who worked for several years in Barkla's laboratory and was afterwards appointed professor of physics in University College, Cardiff. In his first paper, communicated by Professor Barkla to the Philosophical Magazine (Dunbar, 1925), experiments extending over a period of years were described. The source of X-rays was a Coolidge tube of the 'broad-focus' type with tungsten anticathode. The source of high-tension current was a 16-inch coil operated by a mercury break, the primary current being obtained from the City supply at 230 volts. Under the conditions of these experiments the J-discontinuities did not appear or were not certainly indicated in absorption, ionization or corpuscular emission, and in general the observations were in agreement with the Compton theory. A second more elaborate investigation was carried out by Dunbar (1928) in the Viriamu Jones Laboratory, Cardiff, and published in an important paper in May 1928. Again the J-discontinuities in the absorption of scattered X-radiation (heterogeneous) were not observed.
Despite his research contributions, when Dunbar became head of department in Cardiff he made it known that he believed that universities should concentrate on teaching and that research was best done in special research institutes such as the National Physical Laboratory in the UK or the Max Planck Institutes in Germany.

Robert Dunbar joined the Edinburgh Mathematical Society in December 1914 while still an undergraduate in Edinburgh. He served on the Committee of the Society in 1923. Margaret P White joined the Edinburgh Mathematical Society in February 1917 while an Assistant in Natural Philosophy at Edinburgh University. She left the Society in 1921 when she married, but her husband continued as a member of the Society throughout his career.

Article by: J J O'Connor and E F Robertson

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JOC/EFR November 2007
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