1895.] The Electrical Measurement of Starlight. 151 



If we take this effect into account, we have as the deflections due 



to 



Regulus 4'75 



Arcturus . ... 8'00 



Assuming now the latest determinations of the parallaxes of these 

 stars to be 



Regulus 0-093" 



Arcturus G'018" 



we have from equation (4) the ratio of their respective intrinsic 

 energies, I, I', the result 



I'll = 75-72, 



showing that Arcturus radiates into space about 75| times as much 

 energy as Regulus in a given time. 



The telescope was next turned to the star t) Bootis, with the 

 result : 



If the radiation to the sky is added, the star's deflection amounts 

 to 1 mm., i.e., a voltage of 0'0028. 



This observation is, however, recorded merely for the purpose of 

 showing that a comparatively faint star is able to give an unmistake- 

 able E.M.F. 



The telescope was next turned on Saturn, whose image was so 

 large that the ends of his rings were probably off the sensitive 

 surface in the cell. The observation was : 



Between the second and third of these experiments the cell had 

 been slightly disturbed, so that the last is not very satisfactory, 

 although it gives the mean result. 



