Electron microscopes operate at tens of thousands times smaller scale than conventional light microscopes and can hence 'see' down to the atomic level. They were first developed in the 1930s. Archie is a pioneer in the use of transmission electron microscopy to examine the structure and deformation of crystals. In these, a beam of fast electrons can be 'Bragg reflected' at small angles by the atomic planes. This 'hall of mirrors' effect makes the intensity transmitted through a thin crystal sensitive to its orientation and to the presence of any crystal defect which bends the planes. High magnification images showing these defects as well as local changes in composition on the atomic scale can now be interpreted with confidence. Archie became head of the Cavendish Lab and has been a Fellow of Churchill since its foundation.