348 



THE SUN'S GIFT OF LIGHT 



A photographic camera is constructed in the same way as this 

 little camera, only a lens is placed behind the pinhole to intensify 



the image, and it is 

 possible to exchange 

 the ground glass plate 

 for a photographic 

 plate. 



There are certain 

 properties of light 

 which seem readily 

 apparent from our 

 daily experiences. 

 We cannot see ob- 

 jects in the dark, 

 but if a light is 

 brought into the 

 room so that it can 

 shine upon them, 

 they become visible. 

 We see them be- 

 cause the light is 

 reflected to us from 

 them. All objects 

 except self-luminous 



bodies are seen by reflected light. Most of the bodies that 

 we know are dark and non-luminous. Sometimes some of 

 these which have polished surfaces reflect the light from 

 a luminous body and thus appear themselves to be furnish- 

 ing light. 



An example of this is often seen about sundown when 

 the sunlight is reflected from the windows of a house, mak- 

 ing them look as if there were a source of light behind them. 



A LAKE MIRROR 



