Abstract

Keywords: Obituaries . Crystallography in general and the International Union of Crystallography (IUCr) in particular owe much to Professor Durward Cruickshank FRS, the eminent crystallographer and structural chemist of high mathematical ability, who died peacefully on 13 July 2007 in his Alderley Edge home near Manchester. He `retired' as Professor of Theoretical Chemistry at the University of Manchester Institute of Science and Technology (UMIST) in 1983 but continued to collaborate very actively with one of us until his death, with his last paper appearing in Acta Cryst . (2007), D 63 , 906-922. Figure 1 Durward Cruickshank transformed the precision of molecular structure determination in three dimensions by X-ray diffraction with research publications that span 60 years and that directly influence at least some 450000 chemical structures, the number currently held in the Cambridge Structural Database alone. Research on the precision and refinement of proteins dominated his attention throughout his last decade, and the Cruickshank Diffraction Precision Index (DPI), an indicator of the precision of a protein structure, is now generally included regularly both in published protein three-dimensional structures as important information and in depositions at the Protein Data Bank (PDB) files. His first paper in Acta Cryst