25 photographic slides showing interference figures and other phenomena:- 3 Idiocyclophanous calcite, 2 annealed & unannealed glass, 1 Newton's Rings, 2 Star mica, 1 Tubular calcite, 4 Nitre, 5 Calcite & and concave selenite, 7 Quartz, 1 Mirror, violet light, 1 Biprism, green light