THE NERNST GLOWER. 



87 



substance having a radiation law similar to platinum, in which case, in 

 order to attain a similar intensity in the visible, the maximum at 1.2/* 

 rises to extremely high values. 



The results obtained are for filaments made from different lots of 

 material, the 220-volt glower being at least 5 years old. The observa- 

 tions have been made at different dates, on different filaments, all in dupli- 

 cate, some quadruplicate, and there is reason for feeling that what has 



cm. De.fl. 



140 



Fig. 58. Emission spectrum of Nernst glower; (a)= 19.6 watts, (6)= 102.5 

 watts; X m ax = I-45M and 1.32 /J., respectively. 



been observed is a reality. No doubt on examination of other makes of 

 filaments, there will be found a variation in the finer details of the emission 

 bands, at low temperatures, but the gross results can hardly be modified 

 without employing a much larger dispersion and a much narrower bolom- 

 eter. Some of these bands coincide with certain ones found in the emission 

 spectrum of the Nernst "heater," the results of which are given in Carnegie 

 Publication No. 35. 



