Labelled A part III - Part of X-ray camera components (labelled A), from a collection relating to the X-ray crystallography research carried out by Dame Kathleen Lonsdale at University College London. Circular disk possibly made of brass, with three holes, one large two small, one small of the small holes has glass. Red wax or resin on back. Labelled A part III - Part of X-ray camera components (labelled A) 1930-1970