In Memoriam: E S Fedorov

Among the scientists who in various ways paved the way for Laue’s discovery and for Bragg’s determination of crystal structures, there is one who occupies the most important place: E. S. Fedorov (18531919), the eminent Russian crystallographer. His most outstanding achievement is the derivation of the 230 symmetry space groups which now serve as the mathematical basis of structural analysis. Already in his first excellent book, The Elements of Conjigurations, Fedorov clearly outlines the idea of this derivation. From his autobiography it is known that he started writing this book in 1879, at the age of 26, prior to his enrollment as a student at the Mining Institute (Gorny Institute) .* During the years 1881-1882 Fedorov gave many of his papers on ‘the theory of crystal structures’ before the St. Petersburg Mineralogical Society. In 1883 the finished book was accepted for printing on the recommendation of A. V. Gadolin, member of the Academy, the wellknown author who derived the 32 crystal classes. Nevertheless, the book was published only in 1885 in the form of the 21st volume of Transactions of the Mineralogical Society (xapiski Mineralogicheskogo 0 bshchestva) . An important point, underlying the future derivation of space groups, is found on page 240 of this book. Proof of the theorem that ‘every real point system is a system of corresponding points of stereohedra’ is substantiated by the following specific remark by Fedorov: ‘In the past, the definition of real point systems has been taken from Sohncke. But equally, this term is applicable also to an aggregate of other real systems where one is symmetrical with the other.. . If, for the purpose of differentiating, systems of points with symmetry planes are