METHODS OF LIGHTING 



249 



TABLE OF INTENSITIES OF COMMON TYPES OF LIGHTING 



The common carbon incandescent lamp 



The small tungsten incandescent lamp 



The fishtail gas flame 



The Welsbach gas flame 



A zoo-watt tungsten incandescent 



1 6 candle power 

 20 " " 



22 " " 



60 " " 



Q2 " 



// / ; i \ \ \ 

 ' / / ; I I ' \ ' 1 



' / I \ \ V ' 



x /T*M 



Explain how these pictures illustrate direct, indirect, and semi-indirect lighting. 



Methods of lighting. Several ways of lighting by elec- 

 tricity are now in use. In direct lighting, the light is thrown 

 directly from the lamp or by a reflector to the place where 

 it is used. This produces a glare in some directions and 

 has some disadvantages which we shall study in connec- 

 tion with the eye. Direct lighting is economical because 

 little light is lost through diffusion or absorption. 



