MEASURING HEAT FROM STARS 



437 



avoid the blue stars of less than the fourth magnitude, owing to the 

 difficulty in measuring their radiations. However it w-as found possible 

 to measure the heating effect of red stars down to the 6.7 magnitude. 



Fig. 3. Ikonclad Thomson Galvanometee Used in Measuring the Electric 

 Current Generated by the Thermocouples. One of the iron shields 



Is shown to the right. 



Tf it had been merely an attempt to show the possibilities of the 

 instruments, then by selecting red stars, and by increasing the galva- 

 nometer sensitivity, positive indications could have been obtained of 

 radiation from stars of the eighth to ninth magnitude. That, however, 

 would have been simply a spectacular achievement, to awe the layman, 

 and under the present conditions of observation, could not contribute 

 much to science. 



The aim w-as to do one thing thoroughly, rather than to attempt a 

 varied program. This one thing was the establishment beyond all 

 reasonable doubt, by two distinct methods, that the red stars as a 



