SATURDAY 28 JULY 2007 THE INDEPENDENT

Durward Cruickshank, Emeritus Professor of Chemistry of the University of Manchester Institute of Science and Technology (Umist), was an eminent crystallographer and structural chemist. 

From the late 1940s onwards, his mathematical abilities and analyses transformed theprecision of the molecular structures determined in three dimensions by the technique of X-ray crystal structure determination. This technique is very widely applied to determine the three-dimensional shapes of molecules of importance in biology, chemistry, materials and physics. 

Cruickshank's resesrch publications spanned an amazing 60 years and he had a direct influence on some 450,000 chemical structures, the number currently determined and held in the Cambridge Structural Database alone. Proteins were the focus of his research in his last decade and he has the Cruickshank Diffraction Precision Index (DPI) indicator of the precision of a protein structure now being added regularly to the protein 3D structures deposited in the Protein Data Bank (PDB). 

In his "retirement", with various colleagues in the UK and the United States (including me), Cruickshank also joined in the development of the "Laue diffraction" white-beam synchrotron method applied today to sub-nanosecond X-ray diffraction measurement techniques studies and also to the study of micron-sized(i.e. tiny) crystal samples. This method has also led ultimately to more effective exploitation of neutron beams from research reactors for crystallographic studies of the hydrogenation details of water molecules.

Cruickshank began his engineering studies at Loughborough College, as it was known then, and obtained an external London University degree in 1944. Between 1944 and 1946 he worked for the Admiralty on Naval Operational  Research matters, including underwater submersibles. Subsequently he studied Mathematics at St John's College, Cambridge, "learning at the feet of Bondi, Hoyle, Boys and Dirac", as Durward put it. His entry into the world of crystal structures took off when he joined E.G. Cox's (later Sir Gordon Cox)  chemical crystallography group at Leeds University in 1946. 

In 1950 he was appointed Lecturer in Mathematical Chemistry at Leeds University. He was subsequently Joseph Black Professor of Chemistry at Glasgow University, 1962-67, and Professor of Theoretical Chemistry at Umist from 1967 until his retirement. 

He won the Chemical Society (now Royal Society of Chemistry) Award for Structural Chemistry in 1978 and the (first) Dorothy Hodgkin Prize of the British Crystallographic Association (BCA) in 1991. He also delivered the prestigious Bragg Lecture both at Leeds University, during the annual BCA Conference of l997 and to the public at the Royal Institution in London. Durward was made a Companion of Umist in 1992 and was awarded an Honorary Degree in 2004. He also received an Honorary DSc from Glasgow University, and the university's Diffraction Laboratories are named after him. 

Cruickshank was an early pioneer of the use of digital computers. The first stored program computer was invented and built in Manchester, a key engineering breakthrough being the "Williams cathode ray tube memory store" on which blips of 0s and 1s were stored. Durward would travel from Leeds for round-the-clock runs of crystallographic computations on the commercialised Ferranti machine. He attended the Cambridge Summer School in 1950 on Programme Design for Automatic Digital Computing Machines, which was amongst the world's first summer schools on electronic computing. This introduced Cruickshank to the principles of computer programming, machine order codes and binary arithmetic. 

He published extensively in Acta Crystallographica from 1948 onwards on topics in crystal structure refinement. One example of his early seminal contributions was his careful and rigorous analysis of atomic thermal vibrations. He and his first research student, Farid Ahmed from Canada, while in Leeds sorted out conflicting earlier results on the carboxylic group in oxalic acid dihydrate, producing bond distance estimates for the C=O of 1.187 +/-0.022 Å and for the C-O(H) of 1.285 +/-0.012 Å. These he was able to compare with gas phase electron diffraction studies through collaborations with the group in Oslo. These results became relevant to my lab's studies this year on the protonation states of the carboxyl side chain amino acids in proteins; thus Durward's last publication is in the August 2007 issue of Acta Crystallographica. 

Durward had many interests, notably linking to mineralogy and theoretical electron density studies of molecules throughout his career. His retirement symposium was held in Manchester in 1984, although he remained at Umist as an Honorary Professorial Fellow. My lecture at his retirement symposium was on synchrotron Laue diffraction of protein crystals based on my work at the new Daresbury Synchrotron Radiation Source (SRS), and which had aroused Durward's interests for our starting collaboration. Durward brought great mathematical insight to the geometric analyses and specific insights into the use of the gnomonic projection. These had the useful property of turning the curved lines of spots in the Laue pattern into straight lines. The biggest pleasure for us - Cruickshank, Helliwell and Professor Keith Moffat - was, however, in the theoretical analysis of the multiplicity distribution of Laue patterns proving wrong the pessimistic view of Sir Lawrence Bragg that "Laue patterns are too complicated owing to the overlapping reflections problem". We, however, unlike Bragg, had the help of the computer in understanding the complicated Laue patterns from proteins.

Cruickshank did much work for the International Union of Crystallography (IUCr), which he served as Treasurer from 1966, combined with the role of General Secretary from 1970 until 1972. He was Vice-President of the British Crystallographic Association (BCA), 1983-85, and was admitted as a BCA Honorary Member in 2003.

In retirement he researched the genealogy of his family and visited the considerable records archive in Salt Lake City. He was also a keen golfer and an enthusiastic member of the Manchester Literary and Philosophical Society. Crystallographers greatly enjoyed reading of his visits to the Antarctic (1998) and Arctic (2001) in reports that Durward wrote up in newsletters to the science community. En route to the Antarctic he was studying the ship's charts during the voyage and noticed a region called Crystal Sound. On looking more closely he recognised some rather familiar crystallographers' names given to the little islands and rocks in the Sound: Bragg, Bernal, Fowler and Pauling to name a few. Further south were Megaw Island, Nye Glacier and Perutz Glacier. 

With help from the British Antarctic Survey and the Scott Polar Research Institute, both in Cambridge, and colleagues, he eventually learnt how these bleak places got their names. The Antarctic Place-names Committee had decided to use the names of pioneers in techniques, crystallography being amongst them, which had helped in the elucidation of Antarctic problems. 

During our period of collaboration over the last 25 years Durward Cruickshank called himself "J.R.H.'s irreverent postdoc". From my view of it, his mathematics and chemistry input was like having the capabilities of a Ferrari arrive on the scene. He became Visiting Honorary Scientist at the SERC Daresbury Laboratory with me in 1983 and later a Visiting Honorary Professor at York University when I moved there to the Physics Department in 1985 as a member of the academic staff. We both visited and worked extensively with Professor Keith Moffat, in Cornell and latterly Chicago and Argonne National Lab, on the Laue method. Keith and I associated Durward with a rigorous drive to get at the first principles; the quick answer was never enough. 

John R. Helliwell 

Durward William John Cruickshank, crystallographer: born London 7 March 1924; Research Assistant, Chemistry Department, Leeds University 1946-47, Lecturer 1950-57, Reader in Mathematical Chemistry 1957-62; Fellow, St John's College, Cambridge 1953-56; Joseph Black Professor of Chemistry, Glasgow University 1962-67; Professor of Chemistry, University of Manchester Institute of Science and Technology 1967-84 (Emeritus), Deputy Principal 1971-72; FRS 1979; married 1953 Marjorie Travis (died 1983; one son, one daughter); died Alderley Edge, Cheshire 13 July 2007.