356 



THE SUN'S GIFT OF LIGHT 



FIGURE 105 



be bent toward the thicker part of the lens. (See Figures 



104 and 105.) 



If in Experiment 100 a convex lens is placed behind the 



small hole, the rays of light from a large area will be focused 



on the ground glass. If the 

 plate is adjusted to the right 

 - position, a small, distinct picture 

 will be formed. If a plate cov- 

 ered with chemicals that undergo 

 change when exposed to light 

 replaces the ground glass, a 



copy of the picture is left upon the plate. When this is 



developed by chemical process, permanent pictures may be 



printed from it. This is what is done in photography. 

 In the magnifying glass (Figure 106) the eye is placed near 



the lens and the rays from a small object are so bent that 



they appear to be 



spread apart and to 



come from a much 



larger object. The re- 

 fracting telescope and 



the compound micro- FIGURE IOG 



scope (Figure 93) are 



combinations of magnifying lenses so adjusted as to produce 



the largest possible clear image of the object examined. 



Light and Color. Experiment 106. Darken the room except 

 for a small hole in the curtain where sunlight may enter. Allow 

 the sunlight to pass through a glass prism and to fall upon a white 

 wall or a piece of white paper. How has the white sunlight been 

 affected? Where did the colors come from? In what order are 

 the colors arranged ? 



Hold a piece of red glass close to the prism and between the prism 



