EVOLUTION IN THE SUNS 67 



because there are many nebulse in which the 

 spectroscopic findings would indicate a very 

 high temperature, yet other things do not 

 favour such a view, and it may well be that 

 in such regions electrical charges causing 

 transformations of energy at high potentials 

 are the causes at work. Also, in the case of 

 our sun, there may be other forms than heat- 

 energy at work giving the spectroscopic 

 results. 



If these results of enhanced spectral lines 

 as obse'rvable in the solar spectrum, however, 

 be taken as due to temperature alone, then 

 the solar temperature far exceeds that of 

 the electric arc which gives the highest tem- 

 perature of matter en masse known to us 

 terrestrially. 



As has been stated above, the temperature 

 of the high tension vacuum spark cannot be 

 measured, so meanwhile it must be left as an 

 open question. Experimentally the effect 

 that has been obtained by passing from the 

 low-tension air-arc to the high-tension arc, 

 may be expressed from the standpoint of 

 energetics by saying that in the former 

 case a large amount of matter has been heated 

 to a high temperature, in which it volatilizes 

 at considerable pressure, while in the latter 

 case by concentration of much energy at high 



