Bawrett — Amount of Light Scattered from Rough Surfaces. 193 



I now pass to Method B, wliioli consists in reducing tlie intensity of the 

 stronger light by an absorbing medium. For tliis purpose the following 

 arrangement is adopted ; it is in principle somewhat similar to the " colori- 



meter " often used in chemical analysis, and is an adaptation of the method I 

 recently patented for determining tlie " light-tlireshold" of the eye.' Tlie 

 absorbing medium is a liquid of neutral tint, best formed from fine China or 



See Patent No. 2il62, November, 190?. 



