'Correspondence with Cross & Vousden 1957.' Comprises correspondence with L E Cross of the Electrical Research Association, 1957; typescript of an article entitled 'Electric double hysteresis in (Kx Na1-x) NbO3 single crystals'; offprints of M H Francombe and B Lewis, 'Structure and Phase Transitions of Ferroelectric Sodium-Lead Niobates and of other Sodium Niobate Type Ceramics', 1957, and P Vousden, 'The Structure of Ferroelectric Sodium Niobate at Room Temperature', 1951; and correspondence with P Vousden, University College of South Wales and Monmouthshire.