Sir William Henry Bragg

Sir William Henry Bragg 1862-1942, English physicist, educated at King William's College, Isle of Man, and Trinity College, Cambridge. He served on the faculties of the Univ. of Adelaide in Australia (1886-1908), the Univ. of Leeds (1909-15), and the Univ. of London (1915-23). From 1923 he was Fullerian professor of chemistry in the Royal Institution and director of the Davy-Faraday research laboratory. He shared with his son W. L. Bragg the 1915 Nobel Prize in Physics for their studies, using the X-ray spectrometer, of X-ray spectra, X-ray diffraction, and of crystal structure. He became a Fellow of the Royal Society in 1906 and served as president of the society from 1935 to 1940. In 1920 he was knighted. Among his works are The World of Sound (1920), Concerning the Nature of Things (1925), An Introduction to Crystal Analysis (1929), and The Universe of Light (1933). With W. L. Bragg he wrote X Rays and Crystal Structure (1915, 5th ed. 1925).

Bibliography: See biography by Sir Kerr Grant (1952).

Bragg crystal spectrometer An instrument that uses a crystal to split X-rays according to energy, just as a prism splits visible light into the colours of the spectrum. It is named after the British physicist William Henry Bragg (1862–1942). The device has the highest resolution of any X-ray spectrometer, but suffers from low efficiency and can operate only in a very narrow band. It has been used to best effect in studies of the Sun, but has also been flown on X-ray satellites such as the Einstein Observatory.