scientist, invented an instrument which he termed 

 the phenakistoscope, and by which he demonstrated 

 the principle of the persistence of vision; that is, the 

 retention of an illuminated image in the retina after such 

 illumination has been quenched. From this instru- 

 ment was subsequently developed the zoetrope or 

 "wheel of life" a toy which many readers will doubt- 

 less remember. It consisted of a hollow cylinder 

 revolving on a pivot and having a band of short, per- 

 pendicular slits, close together, perforated in its cir- 

 cumference. If a strip of pictures of the same object 

 hi different positions were placed around the inner 

 surface of the cylinder, and the instrument rapidly 

 revolved, the effect of the series of pictures, passing 

 in succession in front of an eye placed on a line with the 

 row of slits, was that of the pictured objects performing 

 some sort of motion, as a horse running, a bird flying, 

 or a human being dancing. 



No further interest seems to have been taken in the 

 matter until after 1870 when a Frenchman, Raynaud 

 by name, modified and improved the zoetrope by re- 

 flecting the succession of images in a many-sided mir- 

 ror placed within the cylinder. This instrument, which 

 Raynaud called the praxinoscope, gave precisely the 

 same effect as the zoetrope. It must be understood 

 that the pictures used in these toy instruments were 

 not photographs but a series of colored reproductions 

 of drawings, and consequently, while this whole matter 

 does not come under the head of chrono- or animated 

 photography proper, some account of it in the history 

 of the pictorial representation of motion is necessary. 



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