(b. July 2, 1862, Wigton, Cumberland, Eng.
d. March 12, 1942, London) British scientist, a pioneer in solid-state physics.
With his son (William) Lawrence Bragg (18901971), he shared a 1915 Nobel Prize for research on the determination of crystal structures and Lawrence's discovery (1912) of the Bragg law of X-ray diffraction . The Bragg ionization spectrometer William designed and built is the prototype of all modern X-ray and neutron diffractometers; the two men used it to make the first exact measurements of X-ray wavelengths and crystal data.