95 THE ROYAL SOCIETY OF CANADA 
4. In deducing the formula just given, we have employed the 
simple exponential law of absorption 
This by itself involves a violation of the principles of conservation of 
energy. In the cases of gases, we know that absorption of light is 
accompanied by lateral scattering according to the well-known Ray- 
leigh Law. In the case of incandescent solids, the problem is very 
much more complicated. Each of the radiating elements besides being 
subject to a primary disturbing cause is also subject to the aggregate 
radiation from all the other elements in the surface S. This constitutes 
what Schuster’ has called “Radiation in a Foggy Atmosphere.’ The 
complete expression of this problem can be given in terms of an integral 
equation in three dimensions. This, together with some applications 
to the intensity of sky light the writer hopes to communicate in a future 
paper. 
1 Schuster, Astrophysical Journal, Jan., 1905, p. 1. 
