Fig. 1. 



COURSE OF KAYS THROUGH APPARATUS IN THE DETERMINATION OF LENGTHS OF WAVES OF 



OBSCURE HEAT. 



^'r^.ir. 



Fig. 2. 

 SPECTRUM FORMED BY PRISM IN DETERMINATION OF WAVE-LENGTHS 

 iB° ,„. 47° ^. 46" „„. 43° 



46" 



<3p 



■*»' 



II 



