Schmidt & Haensch, Berlin S. 



83 



of 235 mm diameter for photographs not exceeding 13 X 18 cm. (Fig. 21.) 

 This and camera c are specially adapted for photography. 



Fig. 21. 



III. Optical Benches for demonstrating polarization and spectrum 

 phenomena and for microscopical projection on the screen. 



a) Large optical bench. 



It consists of an iron bench fixed upon a mahogany base board 

 provided with 6 sliding blocks which may easily be moved along the 

 bench and clamped in any position. 



The standards for various appliances attached to these sliding 

 blocks are fitted with rack and pinion for adjusting the heights. 



The equipment is, of course, adapted for the optical departments 

 which are to be demonstrated. For polarization with parallel and con- 

 vergent light two large Nicol prisms, black mirrors, sets of glasses, 

 glass clamps etc. are supplied with the bench. For spectroscopy a 

 slit arrangement, collimator lens, prisms placed upon a stage etc. 

 accompany the bench. A complete optical bench provided ivith the Schuckert 

 camera le is shown at the exhibition. 



b) Small optical bench, consisting of two stout nickel plated 

 brass tubes mounted upon mahogany base board, provided with 6 or 

 7 sliding pieces with draw tubes for adjusting the height. 



