The team of William Henry and William Lawrence Bragg is certainly one of themost scientifically productive in history. Combining their intellect and research skills, they succeeded in constructing the first X-ray spectroscope, establishing the science of X-ray crystallography . They were jointly awarded the 1915 Nobel Prize for Physics and remain the only father-and-son team ever so honored. William Henry Bragg was educated on the Isle of Man, at King William's College. Always at the top of his classes, he was particularly talentedin mathematics. He entered Cambridge at age nineteen to study physics under John William Strutt, Lord Rayleigh (1842-1919) and Sir Joseph J. Thomson (1856-1940). Thomson steered Bragg to an opening in the physics and mathematics department at the University of Adelaide, Australia, and Bragg undertook the long sea voyage, becoming a professor in 1886. During the next eighteen years,he would establish a reputation as a masterful lecturer; however, he published almost nothing and until he was forty-one conducted no original research. The turning point in Bragg's career came in 1906. As co-president of the Australasian Association for the Advancement of Science, he was expected to deliver an address. For his topic, Bragg chose the recent breakthroughs in radioactivity that had been discovered by Antoine-Henri Becquerel (1852-1908), MarieCurie, and Pierre Curie (1859-1906). While researching the subject, Bragg became quite interested in it himself; he found certain flaws in reasoning in the accounts he read and decided to conduct his own research in the field. Forthe next two years he made his own not inconsequential contributions to radiation physics, particularly in the study of alpha particle emission. He also published his findings regularly, achieving worldwide respect. Meanwhile, hisson, William Lawrence Bragg, was walking firmly in his father's footsteps: recognized as a child prodigy, the younger Bragg entered the University of Adelaide when he was fifteen. He spent much time observing and assisting with hisfather's research, and the two would often spend long nights discussing their findings. William Lawrence Bragg was, in fact, the recipient of Australia'sfirst medical X-ray examination, when his father used a home-built X-ray machine to examine his fractured elbow. In 1909 the Braggs returned to England,William Henry to teach at Leeds, William Lawrence to attend graduate coursesat Cambridge (he had graduated from Adelaide when he was eighteen). At that time, the British scientific community was excited about Max von Laue 's (1879-1960) discovery of X-ray diffraction. Laue had used a crystal to create a diffraction pattern, proving that X-rays were transverse electromagnetic waves,like those of light. Both Braggs immediately became intrigued by this discovery and discussed between them the ramifications. William Lawrence developeda system of equations based upon the theory that crystals were arranged in planes of molecules; using these equations (now known as Bragg's law ), they began the series of experiments that culminated in the invention of the X-ray spectroscope in 1913. They published their work in 1913 and that year were awarded the Nobel Prize; then twenty-five, William Lawrence was the youngest person to win the prize. The first application of the X-ray spectroscope was toexamine the structure of certain crystals. The Braggs discovered that sodiumchloride crystals are not made of molecules at all, but rather patterns of sodium ions and chloride ions, providing more support for the Bohr model of theatom. This early experiment also served as the foundation for the science ofX-ray crystallography; crystallography has since become an important tool for chemists and mineralogists and was the key process in the research of DNA structure. Though their accomplishments as experimental physicists gained thema place in the highest ranks of the scientific community, the Braggs each possessed the ability to convey the wonders of science to the common man; William Henry was a sought-after public speaker in Europe, and William Lawrence enjoyed writing science books for children. William Henry Bragg was knighted in1920, William Lawrence Bragg in 1941.
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