Andrew Richard Lang. 9 September 1924—30 June 2008

Andrew Lang will be remembered internationally for having developed the technique of X-ray topography which enables individual defects, such as dislocations, stacking faults, small angle boundaries and magnetic domains, to be imaged in many different types of materials. His interests spanned the whole range of dislocation studies and he made many important contributions to advanced instrumentation for X-ray crystallography, including pioneering experiments with a synchrotron radiation source. His career began during the last year of the Second World War when he was appointed to a research position at the Unilever Research Laboratories at Port Sunlight, Cheshire. He held research positions at the University of Cambridge, where he completed his PhD, and after a period at the Philips Laboratory in Irvington-on-Hudson in the USA, he obtained a tenured post at Harvard University. He returned to the UK in 1959 as a lecturer at Bristol University, where he was to remain for the rest of his life, being successively promoted to reader and then professor.