126 



SCIENTIFIC RECREATIONS. 



rotation given to the Praxinoscope. To supply the decorations, he arranges 

 on the black foundation the image of an appropriate coloured design by 

 means of a piece of glass. It is well known that transparent glass possesses 

 the property of giving a reflection of the objects on the nearest side as well 

 as on the farthest. We may recall the applications of this optical effect in, 

 theatres, and also in courses of physics, under the title of impalpable spectres. 

 It is also by reflection on thin, transparent glass, that M. Reynaud pro- 

 duces the image of the ornamentations in the Praxinoscope TJuatre. The 

 decorations are really placed in the lid, which is held by a hook in a verti- 



n 



Y 



Fig. 129. 



Fig. 128. M. Reynaud's Praxinoscope. 



cal position, thus forming the front side of the apparatus (fig. 130). In this 

 side a rectangular opening is made, through which the spectator (using both 

 eyes) perceives at the same time the animated reflection of the Praxinoscope, 

 and the immovable image of the decorations reflected in the transparent 

 glass. The position of the latter and its distance from the coloured decora- 

 tions are arranged so that the reflection is thrown behind the moving figure, 

 which consequently appears in strong relief against the background, the 

 effect pspduced being very striking. It is evident that to change the 

 decorations it is only necessary to place in succession on a slide the different 

 chromos representing landscapes, buildings, the interior of a circus, etc. It 

 is easy to choose an arrangement suitable for each of the moving figures 



