Stereoscopic Photographs of Crystal-Structure Model

Abstract

AVERY handy little folding stereoscope has been placed on the market by Messrs. Adam Hilger, Ltd., under the name of a ‘camerascope,’ together with a series of double (stereoscopic) photographs of crystal-structure models, prepared under the direction of Sir William and Prof. W. L. Bragg, to illustrate the more striking and fundamental results of the X-ray analysis of crystals. Both the instrument, when its three hinged parts are folded together (the two outer ones upon the middle basal part), and the forty-one cards on each of which a complementary stereoscopic pair of photographs is printed, fit neatly into a cardboard box so small (5 in. × 4 in. × 1J in.) as to go conveniently into the coat pocket. As regards the instrument itself, the front plate of the three thin metallic (blackened) parts, which is arranged upright at right angles to the basal part when unfolded, carries the two stereoscopic lenses, and has a hole of suitable shape and size cut out of it to admit the nose; while the corresponding back-plate, also upright when opened out, is the stage and is fitted with suitable grooves and retaining guides for the reception of any one of the picture-cards, which are 4J in. × 3 in. in size.