anfc its Color* 135 



simply a dark blot without form or shape. 

 Many of you have noticed in a country village, 

 where the streets are lighted with electric arc 

 lamps, what a difference there is in the illumi- 

 nating effect between a clear and a foggy 

 night. When there is a fog, or when the 

 clouds hang low down, we get a reflection 

 from these which tends to diffuse and soften 

 the powerful light rays that are sent out by 

 these lamps. This effect is especially notice- 

 able when the night is only moderately foggy. 

 Each globule of moisture floating in the air 

 becomes a reflector of light, and by myriads of 

 reflections and counter reflections the light 

 (which on a clear night is concentrated) is 

 diffused over a large area, producing an illu- 

 mination which for practical purposes is far 

 superior to that produced on a clear night. 

 When the latter condition prevails the rays of 

 light are so intense on objects immediately 

 surrounding the lamps that one is blinded; so 

 that the places which are in shadow seem 

 darker than they would be if there were no 

 light at all. The only way to prevent this 

 effect is to have the lights so close together 

 that there will be cross lights, which tend to 

 break up the intensity of the shadows. This 

 principle of light diffusion is taken advantage 

 of to produce an even illumination in stores 

 that are lighted only on one or two sides. 

 This is effected by a series of prisms or reflect- 



