IN ITS RELATION TO THE EYE. 



473 



lower edge, 4 per cent.) differs very little, it will be observed, from 

 that of Reflector II. (coefficient of reflection of lower edge, 38.5 per 

 cent.). Any increase of the value of this coefficient above 38.5 per 

 cent., however, caused a much more rapid change in result. 



It may be of interest to append at this point another chart. Chart 

 VIII., Fig. 2. In this chart are represented the best results we have 

 as yet been able to obtain with the dififerent types of translucent and 



(WPERIMEHTflL) 

 INVERTED OPAQUE 

 INVERTED TRflHJLUCEHT 



■fEHDflNT TRTOLUCEMT 



fEriDRHT OPAQUE 

 (COMMERCIAL) 



Fig. 2. Showing a comparison of the best effects we have been able to 

 obtain with different types of lighting. The installations which have caused 

 the least loss in power to sustain clear seeing are the ones which give the 

 lowest maximum brilliancy in the field of view. 



opaque reflectors installed pendant and inverted. From this chart 

 it will be seen that comparatively good results may be gotten with 

 both pendant and inverted reflectors. In general, however, the work 

 has shown that the problem of protecting the eye from excessive 

 brilliancies and of producing at the same time a satisfactory even- 

 ness of illumination presents greater difficulty in case of the pendant 

 than in case of the inverted reflectors and has apparently been less 

 adequately dealt with thus far in the work of reflector designing. 



III. Other Investigations Pertaining to the Hygienic 



Employment of the Eye. 

 These include the effect of different types of eye-shades under 

 different conditions of lighting; the effect of different conditions of 



