550 



Interference and Diffraction. 



No 54 577 - 



54 585. 1 : 2. 



54 577. 1 : 8. 



54 588. 1 : 6. 



54,577. Diffraction Chromoscope after Ives, cf. Figure, with binocular objective and with 



6 image plates, size of image approx. 6.5 cm 



The photo plates are made by Wood's process; they consist of three superposed photographed 

 grating plates each of which has small grating surfaces corresponding to the individual shapes of the 

 image. The gratings of the three plates have graduation of different widths thus producing spectra 

 of different lengths. If lateral illumination is applied to an image plate in the apparatus, the portions 

 of the image plate, which contain only one portion of the grating, cast a definite colour of the spectrum 

 towards the point at which the eye is situated; immediately two or three gratings act simultaneously 

 on the eye, the eye itself perceives a corresponding mixed light. At the places on which the image 

 plate contains no grating the light is not diffracted and no luminous rays pass through the plate 

 to the eye, since the source of light is situated laterally to the photo plate; consequently these portions 

 appear black. The image plates can also be used for objective demonstration (cf. B. Donath: Ad- 

 ditive Farbenwiedergabe nach Wood mit Hilfe von Beugungsspektren, Brunswick, 1906, pp. 125 et seq.). 



Diffraction Chromoscopes for Projection: see Nos. 51,066 and 51,066 a, p. 185. 

 Interference Plate after Lumner-Gehrcke : see No. 54,089, p. 507. 

 Echelon Grating after Michelson: see No. 54,090, p. 507. 

 Interference Air Plate after Fabry and Perot: see No. 54,091, p. 507. 



54.579. Photographs of the Solar Spectrum, after H. A. Eowland . . . 



Sulliman's Journal of Science, 1887/8. Complete series of 10 plates, size 90 x 30 cm, drawn on 

 lines, provided with the normal wave length scale as corrected by Rowland. The series contains all 

 wave lengths from 300 to 695 fifi. 



54.580. - - A single plate 



54.581. Extra Plate of the B lines in same size 



54.582. Extra Plate of the D lines, same size 



The B lines have an expansion of 600 mm, the D lines a distance of 75 mm. 



54.583. 4 Extra Plates with the carbon lines Each 0. 18. 



* 54,584. Dust Glass for colour rings, very pretty experiment by means of the Projection 



Lantern . . . , 



The objective head should be removed from the lantern and a diaphragm having a small round 

 aperture placed in front of the condenser; a bi-convex lens of approx. 50 cm focal distance should 

 now be placed in the luminous pencil so as to render the rays convergent. The dust glass is held 

 immediately behind the lens. 



* 54,585. Reflecting Stephanoscope after von Lommel, small pattern, for demonstrating inter- 



ference of diffracted light, Figure (Fr. phys. Techn. II, 2, Fig. 2877 [II, Fig. 844]) 



* 54,586. - - idem, larger, for objective demonstration 



Polarisation of Light. 



54.587. Polariser and Analyser after Mace* de Le"pinay, for explaining the polarisation of light 

 on a vibrating fibre which is actuated by an electrom&gnetically driven tuning fork, 

 1.5 m long (Ztschr. f. d. phys. u. ohem. TJ. 2, 1888, p. 87; W. D., p. 454 [416]) . . 



54.588. Model for Explaining Polarisation by Reflection and Refraction, Figure .... 



The different directions in which the ether particles vibrate are demonstrated by small cross rods. 



s. d. 

 5. 0.0 



7.10.0 



0.18.0 

 0.18.0 

 0.18.0 



3.12.0 

 0. 4.0 



0.16.0 

 1. 6.0 



11. 0.0 

 0.18.0 



* Can be used with the Projection Apparatus. 



Cl. 3675, 3805, 1598. 



