Cambridge: University Press, 1913.
First edition of this epoch-making paper, which introduced “Bragg’s law” of X-ray crystallography. “The importance of this work cannot be overstated, for it heralded a revolution in the scientific understanding of crystals and their atomic arrangements. This discovery led to many of the most important scientific achievements of the last century, and these continue to the present day. This paper was the beginning of the field of X-ray crystallography” (Bragg Centenary)..
First edition, journal issue, of this epoch-making paper, which introduced “Bragg’s law” of X-ray crystallography. “The importance of this work cannot be overstated, for it heralded a revolution in the scientific understanding of crystals and their atomic arrangements. This discovery led to many of the most important scientific achievements of the last century, and these continue to the present day. This paper was the beginning of the field of X-ray crystallography, a subject that has enabled us to establish the complete structures of crystals, starting from the very simple to the most complex materials, such as proteins, viruses and the molecule that forms the very essence of life, namely DNA. Around 20 or so Nobel Prizes have been awarded for research that has used the ideas described in this paper. Modern genetics, medicine and the study of materials owe an incalculable debt to William Lawrence, who at the astonishingly young age of 22, made a discovery that has changed our understanding of the world around us. Both father and son shared the 1915 Nobel Prize for their work, with William Lawrence remaining to the present day the youngest Nobel Prize winner ever” (Bragg Centenary 1913-2013).
“Bragg started his first important work as a result of the claim–made in 1912 by Friedrich, Knipping, and Laue–that they had observed the diffraction of X-rays by a crystal. William Henry Bragg [Lawrence’s father], who advocated a corpuscular theory of X-rays, was greatly interested in Laue’s work, despite the fact that the observed effect was explained in terms of, and strongly supported Barkla’s alternative wave theory of X-radiation. Lawrence and his father discussed Laue’s findings in 1912, and William Henry developed the theory that the diffraction effect might be explicable as the shooting of corpuscles down avenues between lines of atoms in crystals. Bragg seems to have found this suggestion unconvincing, although he was careful not to contradict his father in public, and after further study of Laue’s paper, came to the conclusion that this was indeed a diffraction effect … In his paper Laue had calculated the conditions for diffracted intensity maxima for the simple cubic system where the incident beam was parallel to one side of the cell … While Bragg concurred with Laue’s identification and treatment of the problem, he nonetheless, in an impressive display of physical insight, reconceptualized the effect as that of the reflection of X rays off crystal planes, and formulated this in the expression L = 2d cos i, which showed the relationship between angle of incidence i, wavelength L, and distance between parallel atomic planes d. (This expression … became universally known in the community of crystallographers as “Bragg’s law.”) This reworking was of far-reaching significance, for when compared with Laue’s expression, Bragg’s law (and the notion of reflection) rendered the process of diffraction easier to visualize and simplified calculation–advantages that were particularly important in the early development of X-ray crystallography” (DSB).
“The history of modern Crystallography is intertwined with the great discoveries’ of William Lawrence Bragg (WLB), still renowned to be the youngest Nobel Prize in Physics. Bragg received news of his Nobel Prize on the 14th November 1915 in the midst of the carnage of the Great War. This was to be shared with his father William Henry Bragg (WHB), and WHB and WLB are to date the only father and son team to be jointly awarded the Nobel Prize. Experiments made in early 1912 by a German team working under the physicist Max Laue, had shown that X-rays could be scattered by a crystal, but they could not quite explain their results in full. It was WLB, at the age of 22 years, who worked out how to interpret their results and how to determine the atomic structures of crystalline solids for the first time. Father and son subsequently continued to work together, solving many crystal structures, including that of common salt and diamond, until the outbreak of the Great War in 1914. Following the war, both WLB and WHB set up renowned research groups devoted to Crystallography, producing ever more important discoveries that have led to over 26 Nobel Prizes.
“WLB came from a middle-class family originating in Cumbria. He was brought up initially in Adelaide, Australia but then moved to England with his parents in 1906, where he was further educated in Cambridge. It was there that he met his wife-to-be, Alice Grace Jenny Hopkinson. She came from a totally different background, one related to the aristocracy and even to royalty. Unlike WLB, Alice had no understanding of science and was of a very different personality. He was shy, private, given to periods of depression, and intensely focussed on his research. Nonetheless he had many outside interests too; bird-watching, gardening, travelling, and especially sketching and painting, and was devoted to his family. It may be that it was this artistic bent, with his keen visual acuity, that enabled WLB at such a young age to succeed where the German scientists had failed, for Crystallography is both a mathematical and visual science. He was certainly not a member of the establishment. Alice, on the other hand, was lively, outgoing and forthright in expressing her opinions. And yet, despite these huge differences, they formed a love-match that persisted throughout all their lives together.
“The story about WLB and his discoveries, his scientific achievements, especially those leading to many Nobel Prizes, have been well documented. However little has been made known about Alice. Fortunately, both left behind hitherto unpublished autobiographies, which reveal much about their personalities and the events that shaped their lives.
“WLB’s account begins with his early years in Australia, his move to England and his famous discovery, followed by his close involvement in his work during Wold War I, where his experiments on sound-ranging enabled the enemy guns to be located with some precision. This is described in much detail. His autobiography is accompanied by many of his sketches made during his extensive travels, and he describes the many famous people whom he met and with whom he worked. Alice’s autobiography gives much detail about her early family members, some of whom were part of the German upper classes. She describes their personalities as well as their idiosyncrasies. After her marriage to WLB, she immersed herself in public duties, becoming Mayor of Cambridge, and Chair of the Marriage Guidance Council, among many other activities. She is particularly revealing about her attitudes to certain individuals within the Royal Society, who shunned her husband after he took over the Directorship of the Royal Institution following a rancorous affair that ended with the ousting of the previous Director. She has interesting comments to make too over WLB’s controversial willingness to write a Foreword to James Watson’s famous book, The Double Helix, in which WLB was compared unflatteringly to Colonel Blimp. Watson has since claimed that it was Lady Bragg who persuaded her husband to write this, but in her autobiography she makes it clear that it was WLB’s decision alone.
“WLB will be remembered, not only for his scientific research, but also for his impact on the many schoolchildren who attended his Schools’ Lectures at the Royal Institution. Approximately 20,000 children attended each year over a ten-year period. These lectures were filled with amazing practical demonstrations covering all areas of science. WLB used to say that he wanted to show science to children.
“WLB and his father can truly be said to have transformed all our lives, for their work has enabled us to understand the structures of metals, organic and inorganic compounds, pharmaceuticals, proteins, viruses, and just about everything that exists in solid form. It is interesting to speculate what the world would look like had WLB not made his discovery so long ago” Glazer, ‘William Lawrtence Bragg and Crystallography,’ blog.oup.com/2015/08/lawrence-bragg-crystallography/).
Pp. 43-57 in Proceedings of the Cambridge Philosophical Society, Vol. XVII, Part 1. 8vo, pp. 159. Original printed wrappers (front wrapper with library ink stamp and a few tiny chips to edges).