140 THE ART OF PROJECTING. 



low courtesies. To spectators he will appear to have 

 a dozen arms or bodies. There will also be as many 

 shadows upon the screen. 



2. Make a wheel to turn in front of the screen, the 



Fig. 107. 



larger the wheel the better. A buggy wheel or old 

 fashioned spinning-wheel make good objects. Let both 

 disk and wheel be turned at the same time. The ap- 

 pearance of the wheel will depend upon its velocity. 

 It may be made to appear as if standing still or moving 

 slowly forward or backward, or as if it had a multitude 

 of spokes. 



3. While the wheel is turning a little in front of the 

 screen, look through the wheel at the shadow of it. 

 Some remarkable curved lines will appear to group 

 themselves about the axles of the wheel and its shadow. 



4. If two wheels of the same size are made to turn 

 one in front of the other while they are in this inter- 

 mittent light, curious curves and fixed straight, light 

 or dark lines and mixed, changing paths can be seen, 

 according to the position the spectator has with refer- 

 ence to the wheels. 



