Pair of 'Porro' type erecting glass prisms (90º of reflection), unsigned, European, 1920-1950. Pair of glass 'Porro' type erecting prisms 1920-1950
Nine prisms in wooden box, including a composite one made out of six different glasses, 5 by Chance of Birmingham, with MS list of the glasses, late 19th century (Wellcome B885) Nine prisms in wooden box 1880-1900
Two pressed prisms in white ophthalmic crown glass, by Chance-Pilkington, St. Asaph,Clwyd, Wales, 1980. To be optically worked for use in binoculars Two pressed prisms in white ophthalmic crown glass 1980
Three prism objects in brass mounts: set of Porro twin prisms in brass demonstration mount; camera lucida attachment for use with microscope; six planer glass round pieces in brass mounts, unsigned, United Kingdom, 1850-1924 (Wellcome No. B1062) Three prism objects in brass mounts 1850-1924