(1890-1971) EnglishMineralogist
Although Sir Lawrence Bragg was trained as a physicist and employed as a physicist or chemist throughout his career, he was tremendously influential in Earth sciences, as he was in metallurgy and medicine as well. After Rontgen discovered X rays in 1895, von Laue demonstrated that the X rays were diffracted in a three-dimensional scattering if passed through the mineral zincblende in 1912. With his father, physicist Sir William Bragg, Lawrence Bragg showed that this complex scattering could be perfectly explained by reflections of the X rays from successive planes of atoms in the mineral structure. A paper on this work is entitled, “The Analysis of Crystals by X-Ray Spec-trography.” He determined the mathematical conditions of this diffraction in an equation that has been named Bragg’s Law. He and his father then developed an X-ray spectrometer which was used to determine the atomic structure of rock salt, diamond, flourspar, pyrite, calcite, cuprite, corundum, and metallic copper. For this breakthrough, the father-and-son team were jointly awarded the Nobel Prize for physics in 1915. Lawrence Bragg was 25 years old at the time.
It is almost a curse to begin a career with such success because everything else tends to pale in comparison. This, however, was not the case with Lawrence Bragg. He went on to apply his X-ray diffraction techniques to minerals, to metallurgy, and finally to medical problems. He slowly worked his way through minerals of increasing structural complexity, finally addressing the silicates. His 1934 book, Atomic Structure of Minerals (rewritten as Crystal Structure of Minerals in 1965) is a summary of these findings. Amazingly, scientists went from having no idea how the atoms are arranged in minerals to a general understanding of crystal chemistry through this single development. This development came from a man who really knew nothing else about minerals, as he admitted in a famous speech to the American Min-eralogical Society.
Bragg would later show how X-ray patterns and thus atomic structure of deformed metal differs from undeformed metals. He devised an X-ray microscope and a “fly’s eye” apparatus to provide the basis for high-magnification optical methods that would be devised later by others. He also proved the crystal chemistry of hemoglobin and of proteins still later, which had profound implications for the medical field. By this time, Bragg’s notoriety had reached throughout Great Britain. He was asked to give the vacation lectures by the Royal Institution and even a highly successful series of television broadcasts on the properties of matter, which further increased his fame. He devised a series of simple but elegant experiments that became classics of British television.
William Lawrence Bragg was born on March 31, 1890, in Adelaide, South Australia, the son of Sir William Bragg, a professor of physics at the University of Leeds, England. He attended Cambridge University, England, where he earned several degrees, including a Ph.D. in physics in 1913. He joined the cavalry in 1915 to serve in World War I. He devised a method for location of enemy artillery using sound and was decorated with the Military Cross in 1918 as a result. In 1919, he joined the faculty at the University of Manchester, England, as a professor of physics. He was a visiting professor at Cornell University, New York, in 1934. Lawrence Bragg was married in 1921; he and his wife, Lady Alice, had four children and numerous grandchildren. In 1937-1938, Bragg served as the director of the National Physical Laboratory of Great Britain before accepting the position of Cavendish Professor of experimental physics at Cambridge University, England, in 1939. His final move came in 1953 when he accepted the position of Fullerian Professor of chemistry at the Royal Institution in London, England. He assumed the role as director in 1954 and remained as such until 1966, when he retired.
He lived the rest of his life enjoying his family and occasionally giving public lectures. Sir Lawrence Bragg died on July 1, 1971.
The career of Sir Lawrence Bragg can be described as nothing less than distinguished. He is an author of more than 180 international publications ranging from cutting-edge scientific to general interest. The impact of many of these publications on geology as well as physics, metallurgy, and medicine cannot be overstated. In recognition of this illustrious career, Bragg received numerous prestigious honors and awards. In addition to the Nobel Prize in 1915 and a knighthood, which he received in 1941, Bragg was named as a Fellow of the Royal Society in 1921. He received the Hughes Medal, the Copley Medal, and the Royal Medal from the Royal Society of London, the Roebling Medal from the Mineralogical Society of America, and the Companion of Honor, a rare distinction for a scientist, among many others.
