Dr Helen Dick Megaw (1907-2002) was Assistant Director of Research at the Cavendish Laboratory in Cambridge. In this photograph she is shown setting a photogoniometer: a piece of equipment used to take X-ray photographs of crystals. Behind her is a ball-and-spoke model of the structure of afwillite, one of the minerals she researched. One of Megaw's drawings of afwillite can be seen in the next image.