THE ACTION OF LIGHT 



or bent to a greater extent than the ray which passed 

 from air into water. 



For our experiment we need only plunge a stick 

 into water and notice that, owing to this property 

 of light, the stick appears bent, from the point where 

 it comes into contact with the surface of the water. 



Some of us may be old enough to remember that 

 once, on either corner of nearly every mantlepiece, 

 there stood an ornament of doubtful utility from 

 which there hung a dozen or more glass prisms. 

 Now the only beauty about these otherwise hideous 

 contraptions was to be seen when light played upon 

 them. Then patches of violet, green, yellow and 

 red were thrown upon neighbouring objects. White 



light, ordinary sunlight that is to say, is really com- 

 posed of various colours — violet, indigo, blue, green, 

 yellow, orange and red — which, when combined 

 together, make light as we know it. When white 

 light passes through a prism of glass, it is not only 

 bent out of its course, but broken up into all these 

 colours. A prism, as we all know, when examined 

 at either end, is seen to be triangular in shape. Put- 

 ting aside for a moment the question of the breaking 

 up of light into its component parts, the path of 



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