Award of the Duddell Medal to Dr. W. E. Williams

Abstract

THE council of the Physical Society has awarded the twelfth Duddell Medal to Dr. W. Ewart Williams, lecturer in physics at King's College, London, who is distinguished for his work in optical design, chiefly in the region of interferometry. The Medal is given to “persons who have contributed to the advancement of knowledge by the invention or design of scientific instruments, or by the discovery of materials used in their construction”. The principal invention of Dr. Williams is that of the reflection echelon spectroscope. The basic idea of such an instrument was described by the late Prof. Michelson nearly forty years ago, but its practical construction seemed impossible until the discovery by Williams that two optically plane surfaces of quartz or fused silica could be placed in permanent optical contact without exerting the mechanical force needed with glass surfaces. He saw that a number of fused silica plates of exactly equal thickness could be built up in the necessary echelon formation without introducing any distortion that would ruin the optical performance of the instrument. The reflection echelon is the only form of spectroscope of sufficient resolving power which can be used in the ultra-violet part of the spectrum, where, in a number of cases, lie the lines of greatest interest from the point of view of ‘fine structure’, a detailed study of which gives us information about the structure of the nucleus in its normal state.