No. 53 930. 



Lenses and Lens Apparatus. 



497 



53926. 1:14. 



53929. 1:16. 



1 ring for stretching paper, 1 small tripod, 1 carrier for 1 candle, 1 carrier for 4 candles, 

 1 pivot holder, 3 silvered plane mirrors (glass) 10, 5 and 3 cm diam., 1 Concave Mirror (German Silver) 

 15 cm diam. and 5 cm focal length, 1 flint glass Prism, 1 Screen with adjustable gap, 1 Glass Cube 



5 cm side, 1 Glass Lens for supplementing the terrestrial telescope, 4 Glass Plates (window glass, 

 ground, red and green glass 8 cm square), 1 rectangular Trough 8 cm square, 1 Paper Screen, 1 Light 

 Screen, 1 Spirit Lamp, 1 Protractor, 1 small Glass Flask 4 cm diam., also Diaphragms, Pasteboard 

 and Tissue Paper. 



53.927. --the same apparatus, fitted with the accessories of the larger Lens Appa- 

 ratus No. 53,925, instead of No. 53,924, fittings otherwise the same as before . . . 



53.928. Pamphlet by Dr. Zwick: "150 optische Versuche zur Veranschaulichung der Grund- 

 lehren der Ausbreitung, Spiegelung und Brechung des Lichtes", bound 



53.929. Optical Bench, Figure, with accessories for demonstrating the path of rays in 

 lenses and concave mirrors, for demonstrating the microscope and telescope, the Bunsen 

 Photometer, etc 



The optical bench consists of a 2 m long measuring bar, divided in centimetres, and constructed 

 of maple-wood; it rests on two massive brass pillars, is mounted on a mahogany board and provided 

 with 14 stands for raising and lowering the lenses, diaphragms, etc. 



The following are included with the apparatus: 3 bi-convex Lenses, 1 bi-concave Lens, these 

 being selected so that they can be used for setting up the microscope and the terrestrial, astronomical 

 and Galilean telescope; also 1 concave Mirror (glass) 120 mm diam., silvered on front and closed by 

 a cap; 1 flint glass Prism, 1 paraffin Lamp, 1 Gap with micrometer screw, 1 white Screen for receiving 

 the images, 1 Screen for concave mirror images, 1 Diaphragm, 1 Light Holder with one light, 1 Light 

 Holder with 4 small lamps for photometry, and 1 White Screen with grease spot. 



53.930. - - idem, fittings of simpler pattern, with the accessories previously mentioned, 

 but without Prism; mirror only 90 mm diam.; gap without micrometer; and with only 



6 stands 



Optical Benches Nos. 53,929 and 53,930 can also be used as Melloni Apparatuses: all parts fitting 

 the same can be obtained from us. 



Further Optical Benches for explaining the Telescope, Microscope, etc., etc.: see later on 

 in list. 



13. 0.0 



0. 3.0 



12.10.0 



s. d. 



9. 0.0 



Cl. 4001. 1358. 



32 



