206 SEC. 7. LIGHT. 



817. Improved Electric Lamp and Lantern for Lecturer's 

 use. John Browning. 



- The lamp is automatic, the carbon poles being drawn asunder in proportion 

 to the strength of the battery power used ; this is effected by drawing iron 

 rods into a hollow coil of insulated copper wire. The lantern has two nozzles, 

 one intended for exhibiting screen experiments in spectrum analysis, polari- 

 sation, refraction, reflection, diffraction, &c., the other for exhibiting diagrams 

 on the same screen, without altering the arrangement of the apparatus for 

 physical experiments. 



818. Lithographs for the Stereoscope, from drawings 

 by J. Muller, Hessemer, Oppel, Nell. 



J. Wilhelm Albert, Frankfort-on- Maine. 



The coloured drawing marked with A (upon grey cardboard) is the 

 original made by the late Prof. Miiller. Images 2, 3, and 4 serve for a 

 stereoscope without glass. The other images refer to stereometrical, astro- 

 nomical, and optical subjects (colour combinations). Some images appear, 

 by a slight -change of position, in IOAV or high relief. 



819. Edelmann's Spectral Lamp, for the projection of 

 spectra, with printed description. M. Ph. Edelmann, Munich. 



821. Duboscq's Lantern. To be used in connexion with 

 the following apparatus : 



1. Top with illuminating lens ; is to be employed with spectral 

 slit and polariscope. 



2. Spectral slit ; can be regulated by means of a fine screw. 



3. Stand with convex lens; serves for the projection of the 

 rays in spectrum experiments. 



4. Two hollow prisms. 



o. Prism plate for two prisms, arranged for being turned and 

 put higher or lower. 



6. Stand with holder for a prism ; can be regulated. 



7. Polariscope. 



8. Lens system, with four-inch illuminating lenses and achro- 

 matic objective ; serves for the projection of photographic and 

 other images of about 3 inches in diameter. 



9. Microscope. This can be screwed to the end of the preceding 

 system of lenses, after the objective has been removed. 



10. Regulator for producing electric light. 



11. Hydro-oxygen gas lamp. 



A. Kriiss, Hamburg. 



Apparatus for the use of Lecturers, to show sketches, 

 drawings of instruments, anatomical preparations, &c., by means 

 of hydro-oxygen illumination, arranged for the projection of 

 opaque objects. A. Kriiss, Hamburg. 



8 2 la. Photogenic Lantern. M. J. Duboscq, Paris. 



