SIGHT 273 



the most pleasure and the greatest feeling of security. The 

 eye is by far the most sensitive sense organ. 



References : 



1. 1501 : 323-325. Taste and Smell. 



2. 1501 : 333-344. The Eye. 



3. 1503 : 419-427. The Senses. 



4. 1803:435-437. The Eye Vision. 

 a. 1505:142-157. The Senses. 



6. 1506 : 237-242. The Sense Organs. 



c. 1506:246-249. The Eye. 



d. 1507 : 340-361. The Eye and Light. 



e. 1509 : 246-275. The Special Senses. 



/. 1510 : 114-116. The Value of the Nerves. Sense Organs. 



g. 1511 : 314-366. The Special Senses. 



h. 1806 : 152-154. The Eye. Color Sensation. 



Experiment 89. Persistence of Vision. Fatigue. 



Apparatus: Piece of cardboard 2" X 2", string, colored 

 cards red, bluish green, yellow, blue, purple. 



a. Punch a hole in each of two opposite ends of the card- 

 board, and in each tie a string in a loop about eight inches 

 long. Draw the head of a man on one side and some parallel 

 lines (to represent prison bars) on the other side. To " put 

 the man in prison " cause the piece of cardboard to revolve 

 rapidly by putting the loops over your two thumbs and turn- 

 ing the cardboard until it winds up the string in spirals, then 

 gently pull the hands apart. The impression which the eye 

 receives from one side of the cardboard lasts until the other 

 side is seen. Therefore both seem to be seen simultaneously. 

 This will explain the moving pictures wherein a series of pic- 

 tures are thrown on a screen with less than a tenth of a second 

 between successive ones. The impression from one lasts 

 until another is seen. 

 T 



