BELL. 



THE PHYSIOLOGICAL BASIS OF ILLUMINATION. 



89 



that the light should come from the left (left-handed people were 

 forgotten). Shadows from the head and shoulders are much more 

 troublesome, as they may exist to an annoying degree in rooms other- 



10 20 uO 40 50 60 



Angles of Incidence 



Figure 4. 



70 



SO 



90 



wise well lighted, and they are in fact difficult to avoid in the general 

 lighting of counting rooms and similar places. 



Finally, one is nowadays often confronted by questions of color. 

 Until electric lighting in its more recent forms appeared there was a 

 sufficient similarity in the colors of artificial illuminants to place them 

 substantially on a parity. At present, strong colors are common, and 



