1886.] 



Radiation of Light and Heat, 



211 



Tables III and VI give the photometric tests of these carbons as I 

 procured them, and diagrams 2 and 3 show the plotting of these 

 tests. I have marked these filaments C and D, the black dotted line 

 in diagram 2 being the curve for filament C, and the black dotted line 

 in diagram 3 that for filament D. 



In these two curves the extreme uniformity with which these car- 

 bons tested is worthy of notice, the one giving nineteen and a half 

 candles and the other twenty for the eighty watts supplied to each, 



