GB428082A - A model for the demonstration of crystal forms and the like - Google Patents

Abstract

428,082. Models; hinges. SMITH, S., The University, Bristol, and GEORGE, Ltd., W. & J., 157, Great Charles Street, Birming- ham. Nov. 8, 1933, No. 31024. [Class 146 (ii)] [See also Group XXV] A model for the demonstration of crystal forms and the like comprises a plurality of linear members some or all of which are extensible, and which are joined together to constitute a three-dimensional geometric structure, with the connections between the adjacent linear members such as to permit of a substantially universal movement whereby the model may be manipulated to illustrate a variety of crystal forms or three-dimensional geometric figures. A cube which may be deformed to the shape shown in Fig. 2 comprises inextensible tubes 5, 7, 13, 15, hingedly connected to extensible tubes 6, 8, 12, 14, 16, which comprise outer tubes and inner sliding rods a, the extent of the outward telescopic movement being limited by spring-pressed catches 24 on the tubes engaging rings or notches on the rods a. Some of the rods a and their respective tubes 7, 8 are connected by a substantially universal joint, Fig. 3, comprising a ball 22 screwing on to the end of the rod a, plates 17, 18 attachable to one tube 7 and having an aperture of less diameter than the ball, and a plate 23 attachable to the other tube 8, or the telescopic rod therein, and having an aperture of larger diameter than the ball. In assembling the parts, the ball 22 is unscrewed and the rod a is passed through the aperture in the plate 18 and reattached to the ball. Then the plates 23, 17 are engaged over the ball, a distance piece 19 is inserted between the plates 17, 18, and the parts 17-19 are adjustably secured together by screws 20<a>.