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Sir William Henry BraggPrint Page Print this page

04-March-2021
04-March-2021

Photographs supplied by Stephen Warren

The portrait bust commemorates Sir William Henry Bragg (1862-1942).

Sir William Henry Bragg was born on 2 July 1862 at Westward near Wigton, Cumberland, England, son of Robert John Bragg, merchant navy officer and farmer, and his wife Mary, née Wood. His mother died when he was 7 and, almost isolated from other children, he was raised by his uncle William Bragg at Market Harborough, Leicestershire. He won scholarships to the local grammar school and to King William's College, Isle of Man, where he became head of the school and won an exhibition to Trinity College, Cambridge. There he worked almost entirely at mathematics; later he regretted this early specialization. Lacking both spending money and easy sociability, he was saved from loneliness by his skill at games. In 1884 he graduated as third wrangler and a year later was awarded a first in part III of the tripos.

In 1886 Bragg arrived in Adelaide to take up the university post of '(Sir Thomas) Elder Professor of Pure and Applied Mathematics, who shall also give instruction in Physics'; it had been recently vacated by, Sir Horace Lamb. He was ignorant of physics, in which he was to become one of the most eminent men of his time. Although at first he had only two students, he did not proceed to engage in any research. He apprenticed himself to a firm of instrument-makers to make apparatus for his deficient teaching laboratory.

Meeting with a friendly reception, particularly from the family of (Sir) Charles Todd, Bragg enjoyed a wide popularity, and his personality blossomed. He played tennis and golf and helped to introduce lacrosse to South Australia. On 1 June 1889 he married Todd's daughter Gwendoline, a skilled water-colourist; Bragg took up painting and they exhibited together. They had two sons, one of whom was later killed at Gallipoli, and a daughter. Bragg was active in the affairs of the Public Library, Museum and Art Gallery of South Australia, the School of Mines and Industries and the Teachers' Guild.

At the university he encouraged student activities, particularly the formation of the union. He believed that the greatest work a colonial university could do was to act as 'the centre from which all education radiates' and help to bring all teachers in touch with the best thinking. His academic interest shifted to physics.  He developed a flair for expounding the subject both in formal classes and in public lectures often enlivened with experimental demonstrations. Electromagnetism interested him; one day in 1895 he was experimenting with a Hertzian oscillator when he was visited by Ernest Rutherford who was on his way to Cambridge and had worked on radio transmission at Christchurch, New Zealand.

Early next year Bragg learned of W. K. Röntgen's discovery of X-rays and, with his able assistant A. L. Rogers, set about producing the new radiation. On 13 June they obtained a photograph with their own Röntgen tube. One of the first beneficiaries was Bragg's 6-year-old son William Lawrence, whose broken elbow was photographed with the primitive equipment. But many years passed before Bragg began his serious studies of X-rays and other ionizing radiations.

In 1898 he spent a year's leave in England; he reported on technical education and the central importance of design in industry. On his return Bragg carried out experimental work on radio communication with Todd. Their transmissions from the State Observatory were successful over a distance of 550 metres on 10 May 1899, and by 20 July, over 8 kilometre from the Observatory to Henley Beach.

The turning-point in Bragg's career came in 1904 when he gave the presidential address to section A of the Australasian Association for the Advancement of Science at Dunedin, New Zealand, 'On some recent advances in the theory of the ionization of gases'. He discussed the penetration of matter by α and β particles, concluding that the massive α particles, unlike the β and γ rays, would move undeviated through a gas until all the energy was lost through ionization of the gas molecules, and consequently α particles of a given initial energy should have a definite range in the gas. This idea was followed up in a brilliant series of researches which within three years earned him a fellowship of the Royal Society of London. He was helped by a student Richard Kleeman, whom Bragg had invited to act as his assistant.

Bragg concluded that X-rays and γ rays were streams of neutral-pair particles rather than electromagnetic waves. This made him the centre of a controversy for several years. In January 1909, shortly before leaving to occupy the Cavendish chair of physics at the University of Leeds, Bragg delivered the presidential address to the A.A.A.S. meeting at Brisbane, in which he summarized his work of the past five years and commented on the significance of scientific research for the development of Australia.

In 1912 Max von Laue showed that X-rays could be diffracted by crystals and established their wave nature. During that summer Bragg and his son William Lawrence, who was then at Trinity College, Cambridge, discussed this development. While the father, with his experience of ionization measurements, went on to construct an X-ray spectrometer for the further study of the properties of X-rays, the son found a brilliant simplification of Laue's diffraction problem and formulated Bragg's Law, relating the location of maxima of the diffraction pattern to the wavelength of the radiation and the distance between the appropriate planes of atoms in the crystal.  From Laue patterns W. L. Bragg derived the structures of ZnS and the alkali halides, and then, joining forces with his father who now had a superior experimental method, they together initiated the whole subject of X-ray crystallography, for which they received the Nobel prize for physics in 1915. W. L. Bragg was then 25.

The outbreak of war temporarily ended this work. W. H. Bragg became occupied with the problems of submarine detection.   In 1915 W. H. Bragg was appointed to the Quain chair of physics at University College, London. Here, and on becoming Fullerian professor of chemistry and director of the Royal Institution of Great Britain in 1923, he built up vigorous schools of X-ray crystallography concerned principally with the study of organic molecules.

W. H. Bragg maintained an active interest in X-ray crystallography until his death and made a monumental contribution to the subject, as well as serving the scientific world in other capacities. Many honours were bestowed upon him by learned institutions, including election in 1920 as an honorary fellow of Trinity College, Cambridge. He was appointed C.B.E. (1917) and K.B.E. (1920) and admitted to the Order of Merit (1931). He received the Rumford (1916) and Copley (1930) medals of the Royal Society of which he was president in 1935-40. He died in London on 12 March 1942 after a period in which heart trouble reduced his activity.

Location

Address:North Terrace, Near National War Memorial, Adelaide, 5000
State:SA
Area:AUS
GPS Coordinates:Lat: -34.921263
Long: 138.600669
Note: GPS Coordinates are approximate.
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Details

Monument Type:Sculpture
Monument Theme:People
Sub-Theme:Science

Dedication

Front Inscription

Sir William Henry Bragg KBE OM FRS

Elder Professor of Mathematics and Physics
University of Adelaide 1886 - 1909

Joint Nobel Laureate with his son Lawrence

Physics 1915

Born Wigton, United Kingdom 1862
Died London, United Kingdom 1942

The donation of this bust to the City of Adelaide was made possible by the generosity of his family, the University of Adelaide
and the efforts of RiAus and friends.

 

Source: MA,ADB
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