Arthur James Cochran Wilson (1914-1995)

A. J. C. Wilson received a masters degree from Dalhousie U., Nova Scotia (1936), and PhD's from Massachusetts Inst. of Technology (1938) and U. of Cambridge (1942) where he received a scholarship the year Sir Lawrence Bragg succeeded Lord Rutherford at the Cavendish Lab. Wilson's work on thermal expansion at Cambridge involved the measurement of precise lattice parameters which led naturally to a general investigation of experimental factors which influence the position, shape and intensity of X-ray diffraction lines. When asked to review a paper on deriving absolute from relative intensities of X-ray diffraction data, Wilson first became aware of the analytic power of crystallographic statistics. The complex method described in the paper suggested a simpler approach to Wilson, which he published in Nature. This eventually became one of the most frequently cited papers in crystallography. The Wilson Plot is still used for scaling intensities and estimating temperature factors. At Cardiff he founded a school of organic crystal chemistry which achieved world-wide recognition for its work on alkaloids, terpenoids and amino acids. His research students included David Phillips (Lord Phillips of Ellesmere, KBE, FRS), Eric Stanley (Prof. of Physics of the U. of New Brunswick) and Sukcaki Hosoya (Chair at the Inst. for Solid State Physics, U. of Tokyo). The group contributed substantially to the theory and practice of structure solution. They showed that the symmetry elements of a crystal structure can be deduced from observed diffraction data (1949) including the centre of symmetry which had previously been thought impossible to detect by X-ray methods. Sir Lawrence Bragg said of this discovery 'Like all brilliantly original ideas it seems obvious when pointed out'. In 1970 the Joint Committee on Powder Diffraction Standards (JCPDS) was formed to manage and distribute the Powder Diffraction File (PDF). Bill Parrish and Wilson were pioneers of the modern powder diffractometer, Parrish being responsible for its design, while Wilson developed the theory of diffractometry. Over a period of twenty years the JPCDS Lab at Cardiff enjoyed a reputation as one of the principal centres of powder diffraction world wide. In 1948 Wilson became Editor of Structure Reports, and in 1960 he succeeded Paul Ewald as Editor of Acta Cryst., a post he held until 1977. He was Chairman of the Commission on Acta Crystallographica from 1960 to 1967, Chairman of the Commission on Journals and first Chairman of the Commission of Crystallographic Nomenclature, Vice-President of the Int'l Council for Scientific and Technical Information from 1980 to 1986 and Vice-President of the IUCr from 1979 to 1981. Wilson was involved in the formation of the BCA. He was elected a Fellow of the Royal Soc. in 1963. In 1965 he was appointed Prof. of Crystallography in the Dept of Physics at the U. of Birmingham. In 1984 he received the Distinguished Fellow Award from the Int' l Centre for Diffraction Data and Dalhousie U. awarded him an honorary Doctor of Laws degree in 1991. Few aspects of crystallography, single-crystal and powder methods were not covered in the over 300 papers he published throughout his career. During his retirement he took on the chairmanship of the IUCr's Commission on International Tables and was appointed editor of Volume C. At the time of his death, Wilson was putting the finishing touches to a revision of Volume C. Arthur Wilson was a member of the Society of Friends, a clerk of the Jesus Lane Meeting, Cambridge, a life-member of the Rambling Club and a member of the Alpine Club and the Sierra Club.