372 GENERAL SCIENCE 



Variation in original color produced by the use of various colored 

 lights is often taken advantage of for lighting scenes on stages. It 

 is often impossible to tell the real color of the dress of an actress, 

 or to match material by artificial light. 



The following types of illumination used with the above table 

 will give some hints as to why materials have different colors 

 under different lights. 



Illuminant. Color. 



Sun (high in sky) White. 



Sun (near horizon) Orange red. 



Skylight Very bluish white. 



Electric arc (short) White. 



Electric arc (long) Bluish white to violet. 



Flame arc Commonly, yellow. 



Mercury arc. . Bluish green. 



Nernst lamp Yellowish white. 



Tungsten lamp. Yellowish white. 



Incandescent (normal), carbon Yellowish. 



Incandescent (below voltage), carbon. . Orange to orange red. 



Acetylene flame Yellowish white. 



Welsbach light Yellowish to greenish white. 



Gaslight (Siemens burner) Whitish yellow tinge. 



Gaslight, ordinary Yellowish to pale orange. 



Kerosene lamp Yellowish to pale orange. 



Candle Orange yellow. 



Amount and Position of Window Space. For proper lighting of 

 rooms the amount of window space should be about one-sixth to 

 one-fourth of the floor space. 



The bottoms of all windows should be higher than the eyes of 

 students studying in a classroom, to prevent direct light shining in 

 the eyes of pupils. 



Windows should extend to or nearly to the ceiling of the room. 

 Light should enter one side of the room only, especially in school 

 rooms, to prevent a student facing the light to see the blackboard, 

 or when the head is turned to either side. The light from the 

 windows must never fall in one's eyes. Sunlight should be reflected 



