Bernal's model of the structure of a monatomic fluid, c 1950.
© Science Museum / Science & Society Picture Library
Detail of a model showing random close-packing. John Desmond Bernal (1901-1971) was a physicist and pioneer of X-ray crystallography who built this model in a building in Torrington Square, London, while he was Profesor of Physics at the University of London. Bernal was also interested in Marxist philosophy and the social study of science. Known to his friends as 'Sage', Bernal was very influential in both political and scientific circles.