370M. C. Lea on certain phenomena of Light. 
produced at every point of the glass, these will re-compose 
white light, and the transmitted beam will be white. This 
passes through the glass, let us suppose that the abrasion has 
00475 millimeter, and that the glass has an 
index of refraction of 1:5; it is evident that a mean blue ray | 
whose wave length in air is -000475 mm. will have accom- | 
plished i in Pp 
phase will therefore be precisely the opposite of that of the first 
wave, and these two will be in condition to extinouish 
Fess than that of the pyroyxlin, and in proportion to the 
bety the two. : 3d 
_ When the red light in place of being direct, is, as in the 
case, diffuse, it admits of the following explanation. : 
rays of light entering a medium which holds ss of = 
Tve ° : - = he ; Th 
coos ee in ll be partly 
