LIGHT 



125 



an image apparently larger than the object. Combinations 

 of lenses are used in telescopes, opera glasses, and compound 

 microscopes. 



136. The Eye and the Camera. The photographic 

 camera is constructed upon the same principle as the eye. 

 Light is admitted to the camera through a small opening; 

 it enters the eye through a similar opening called the pupil. 

 In both the camera and the eye, the light then passes through 

 a convex lens into a dark space and there the light produces 

 an image. In the camera, the image is formed upon a plate 

 or a film coated with a sensitive substance upon which light 

 energy causes a chemical change. In the eye, the image is 



FIG. 60. A MAGNIFYING GLASS 



1. Follow three parallel rays of light o, c, b, from-the small arrow through 

 the lens; how is their relation changed after leaving the lens? 2. They 

 pass into the eye and fall upon the retina; where do they seem to come 

 from? 3. What is the difference in appearance between the object and the 

 image? 



formed upon the retina, which is a membrane upon which 

 the ends of the fibers of the nerve of sight are spread out. 



By means of further chemical change which takes place 

 outside of the camera, the image on the film is developed and 

 is made permanent. From the eye, the nerve of sight trans- 

 mits to the brain the effect of the light energy and we are 

 conscious of an image; we "see" the object. 



