230 



GENERAL SCIENCE 



reversed in the picture 

 upon it. This negative 

 may be used to produce 

 any number of positive 

 photographs on sensitized 

 paper (Figure 207). 



The eye is essentially 

 a small camera. Light 

 enters the eye through the pupil, which corresponds to 

 the shutter of a camera. It then passes through the 

 crystalline lens (convex lens) into the dark space and 



FIG. 206. Showing the Inversion of the 

 Image in a Pin-hole Camera. 



FIG. 207. Diagram of a Camera. 



finally forms an image on the retina at the back of 

 the eye. 



Experiment 68. Look obliquely through a block of glass 

 (Figure 208) and set four pins, two on each side of the block, so 

 that they form a straight line. Remove the block and draw lines 

 connecting the pins. Are they in a straight line? 



FIG. 208. 



