SYNTHESIS OF MOVEMENT 307 



are arranged representing men or animals in the various 

 attitudes which correspond to the successive phases of 

 a movement. 



When the disc is spun round on its axis opposite to 

 a mirror, and the eye applied to the blackened side on 

 a level with the revolving slits, the reflections of the 

 various images are seen one after another corresponding 

 to the different attitudes assumed by the original 

 object; this conveys an impression of actual movement. 

 Fig. 202 represents the disc of a phenakistoscope ; on 

 it are arranged the successive photographs of a flying 

 gull. 



If this side is made to revolve in front of a mirror 

 and the eye be applied on a level with the slits, the 

 gull can be seen flapping its wings. The rapidity of 

 the movement depends on the velocity of rotation. 



The disc must be turned in the right direction, other- 

 wise the images will succeed one another in the inverse 

 order to that in which they actually occur, and the 

 direction of movement will appear reversed. 



Zootropes. — The manufacture of these articles became 

 a commercial industry, and some of them were turned out 

 in more convenient forms ; one of them was called the 

 "zootrope," and consisted of a cylindrical chamber 

 revolving on a vertical axis. Narrow upright slits 

 were made round the brim, and inside the cylindrical 

 wall a strip of paper was pasted on which a series of 

 images was arranged so as to represent the successive 

 attitudes of a man or animal in motion. If these 

 figures were observed through the slits while the 

 zootrope was revolving, the same impression as that 

 caused by the phenakistoscope was produced. 



This contrivance, which has been adopted by many 

 manufacturers, possesses one obvious advantage, namely, 

 that several people arranged round the apparatus can 

 watch the phenomenon at the same time. 



