Twenty years of physics: Structural crystallography

THE INFLUENCE of structural crystallography on physics, chemistry and biology is now far greater than it was 20 years ago. By the late 1930's crystallographic studies had laid the groundwork for interpretations of many phenomena of the solid state by providing detailed information on the metric aspects of simple molecular and crystal structures. But 20 years ago the chemist, let alone the biologist, would not come to the crystallographer for the determination of a complex structure. Structures, some of them complex, were being solved then, but the process was slow, uncertain and arduous. Structures were simply not being solved within the attention span of physicists, chemists and biologists, and there is no reason to suspect that that span was longer in those days than now. For the history of x‐ray diffraction and personal reminiscence see P. P. Ewald, Fifty Years of X‐Ray Diffraction, Utrecht 1962.