KNOBLAUCH ON RADIANT HEAT. 



213 



points at which the raised margins of the furrows meet. This 

 constituted a difference between the rolled and the cast plate, in 

 which the transverse stripes also diminished the radiation. 



The following table contains the numbers which have been 

 obtained in different experiments, each being the arithmetic 

 mean of two observations : — 



Table VIII. 



With the same object as that just stated, I made a second 

 experiment. 



Melloni ascribes the increase which the radiation from a cop- 

 per plate undergoes when the latter is scratched, to the circum- 

 stance, that by this proceeding less dense portions would become 



