(1862-1942) English physicist. In 1915 he shared with his son Lawrence Bragg the Nobel Prize for Physics for their research work on X-rays and crystals.
Crystallography had not previously been concerned with the internal arrangement of atoms but only with the shape and number of crystal surfaces. The Braggs' work gave a method of determining the positions of atoms in the lattices making up the crystals, and for accurate determination of X-ray wavelengths. This led to an understanding of the ways in which atoms combine with each other and revolutionized mineralogy and later molecular biology, in which X-ray diffraction was crucial to the elucidation of the structure of DNA.
Bragg was born in Westward, Cumberland. He obtained a first-class degree in mathematics from Cambridge 1885 and was immediately appointed professor of mathematics and physics at the University of Adelaide, South Australia. In 1909 he returned to the UK as professor at Leeds; from 1915 he was professor at University College, London.
Bragg became convinced that X-rays behave as an electromagnetic wave motion. He constructed the first X-ray spectrometer 1913. He and his son used it to determine the structures of various crystals on the basis that X-rays passing through the crystals are diffracted by the regular array of atoms within the crystal.

(William) (1890-1971) Australian-born British physicist. In 1915 he shared with his father William Bragg the Nobel Prize for Physics for their research work on X-rays and crystals.
Bragg was born in Adelaide and studied mathematics there and at Cambridge, then switched to physics. He was professor of physics at the University of Manchester 1919–38 and at Cambridge 1938–54.
He became interested in the work of Max von Laue, who claimed to have observed X-ray diffraction in crystals. Bragg was able to determine an equation now known as Bragg’s law that enabled both him and his father to deduce the structure of crystals such as diamond, using the X-ray spectrometer built by his father. For this, he was the youngest person (at age 25) ever to receive the Nobel Prize.
Lawrence Bragg then went on to determine the structures of such inorganic substances as silicates.

(1817-1876) Confederate general during the American Civil War who was defeated by Grant in the battle of Chattanooga.