380 C. C Hutchins — Irregular Reflection. 



The annexed table gives the values of <j and G for a few 

 bodies and the resulting value of the albedo. 



G. (j. Albedo. 



Plaster 158 108 92-7 



Magnesia ._ 158 86-3 47'6 



Paper 159 151 82*6 



Green leaf, upper side .. 116 403 30'2 



Green leaf, under side __ 116 506 38-0 



Volcanic rock 192 60*2 27*4 



Brown soil.. 192 697 31'? 



The photometric value of the albedo of white paper is 68, 

 with which the number found above agrees very well. The 

 comparatively large values found for dark bodies like the soil 

 are probably due in part to heat absorbed and re-radiated. The 

 less the reflecting power of a body, the more prominent would 

 this radiant part become. 



The case of magnesia is rather peculiar ; although it seems 

 white to the eye as though reflecting all rays equally, it never- 

 theless absorbs a large portion of the longer waves. 



Searles Physical Laboratory, Bowdoin College, July, 1898. 



