Sir William Lawrence Bragg

Born Mar. 31, 1890, in Adelaide. English physicist; member of the London Royal Society (1921). Son of Sir W. H. Bragg.

Bragg studied at the universities of Adelaide (Australia) and Cambridge. From 1919 to 1937 he was a professor at the University of Manchester. In 1937-38 he was director of the National Physical Laboratory and from 1938 to 1953 he was director of the Cavendish Laboratory. From 1954 to 1966 he was director of the Royal Institution in Cambridge. In 1913, simultaneously with G. V. Vul’f, he gave the equation connecting the angle of deflection of X rays scattered by a crystal with no change in wavelength with the distance between neighboring atomic planes in the crystal (the Bragg-Vul’f condition). He developed methods for deciphering complex crystal structures according to the intensity of an X ray scattered by a crystal, and he put into practice the technique shown by Sir W. H. Bragg for determining structures by means of Fourier series. He also determined the structures of many silicates. He received the Nobel Prize in 1915.