88 



THE ART OF PROJECTING. 



THE KALEIDOSCOPE. 



The very great beauty and variety of the forms seen 

 in the kaleidoscope makes them very desirable objects 

 for projection. The following method will be found 

 efficient : 



i st. With porte lumiere. 



Fig. 66. 



The condenser c may have a focus for parallel rays 

 from a foot to eighteen inches or more. Choose an 

 objective 0, with focal length of eight or ten inches. It 

 does not need to be more than an inch or two in diam- 

 eter. Now cut two strips of looking-glass two or three 

 inches broad and an inch shorter than the focal length 

 of the objective. These may have the same breadth 

 throughout, or they may taper to an inch broad at the 

 outer end, as shown in the picture. They may now 

 have their long edges brought together on one side 

 and inclined to each other forty-five or sixty degrees, 

 and secured there by enclosure in a tube ; or, if it be for 

 temporary use, they may be held in place by a retort 

 clamp and work just as well. The condenser c may 

 now be placed close to the orifice and its focus will 

 then be at some place o. Bring the fixed reflectors 

 within the converging rays, so that they will receive the 



