Sir William Henry Bragg (2 July 1862 – 12 March 1942) was an English physicist, chemist, mathematician, and active sportsman who uniquely[1] shared a Nobel Prize with his son Lawrence Bragg – the 1915 Nobel Prize in Physics: "for their services in the analysis of crystal structure by means of X-rays".

[3][4][5] In 1885,[6] at the age of 23, Bragg was appointed (Sir Thomas) Elder Professor of Mathematics and Experimental Physics in the University of Adelaide,[7] Australia, and started work there early in 1886.

Also at that time, there were only about a hundred students doing full courses at Adelaide, of whom less than a handful belonged to the science school, whose deficient teaching facilities Bragg improved by apprenticing himself to a firm of instrument makers.

The tube had been obtained at Leeds, England, where Barbour visited the firm of Reynolds and Branson, a manufacturer of photographic and laboratory equipment.

[9] At the University, the tube was attached to an induction coil and a battery borrowed from Sir Charles Todd, Bragg's father-in-law.

The induction coil was utilized to produce the electric spark necessary for Bragg and Barbour to "generate short bursts of X-rays".

[10][11] As early as 1895, Bragg was working on wireless telegraphy, though public lectures and demonstrations focussed on his X-ray research which would later lead to his Nobel Prize.

There were many common practical threads to the two technologies and he was ably assisted in the laboratory by Arthur Lionel Rogers who manufactured much of the equipment.

[12][13] Bragg departed Adelaide in December 1897,[14] and spent all of 1898 on a 12-month leave of absence, touring Great Britain and Europe and during this time visited Marconi and inspected his wireless facilities.

[14][15] He returned to Adelaide in early March 1899,[16] and already on 13 May 1899, Bragg and his father-in-law, Sir Charles Todd, were conducting preliminary tests of wireless telegraphy with a transmitter at the Observatory and a receiver on the South Road (about 200 metres).

[18] It was desired to extend the experiments cross a sea path and Todd was interested in connecting Cape Spencer and Althorpe Island, but local costs were considered prohibitive while the charges for patented equipment from the Marconi Company were exorbitant.

At the same time Bragg's interests were leaning towards X-rays and practical work in wireless in South Australia was largely dormant for the next decade.

During his 23 years in Australia "he had seen the number of students at the University of Adelaide almost quadruple, and had a full share in the development of its excellent science school.

[4] He had to wait for almost a year to contribute to the war effort: finally, in July 1915, he was appointed to the Board of Invention and Research set up by the Admiralty.

Bowing to outside pressure to use science, in July 1916, the Admiralty appointed Bragg as scientific director at Aberdour, assisted by three additional young physicists.

In France, where scientists had been mobilized since the beginning of the war, the physicist Paul Langevin made a major stride with echolocation, generating intense sound pulses with quartz sheets oscillated at high frequency, which were then used as microphones to listen for echoes.

The British made sonar practicable by using mosaics of small quartz bits rather than slices from a large crystal.

Inspired by William Lawrence's methods for locating enemy guns by the sound of their firing, the output from six microphones miles apart along the coast were recorded on moving photographic film.

[4] In 1919, 1923, 1925 and 1931 he was invited to deliver the Royal Institution Christmas Lecture on The World of Sound; Concerning the Nature of Things, Old Trades and New Knowledge and The Universe of Life respectively.

Now the cause of science was strengthened by the report of a high-level Army committee on lessons learned in the last war; their first recommendation was to "keep abreast of modern scientific developments".

Gwendolen married the English architect Alban Caroe, Bragg taught William at the University of Adelaide, and Robert was killed in the Battle of Gallipoli.