

XXVI.] 



LATER RESULTS. 



373 



arc as Angstrom did, and with the induction coil as Thalen did, 

 only I have had the advantage probably of using a more 

 powerful coil. In fact I have used two coils one so arranged 

 as to give us the maximum effect of tension, and the other the 

 maximum effect of quantity. In the first place it will be seen 

 there is a general agreement between the observations an 

 agreement marred only in appearance here and there by the fact 



Sun 



Arc 

 Si ark 



Spots 

 Prominences 



Arc 



LQ I 



I 

 T Coil 



trj 



FIG. 119. Showing that in the case of lines frequently seen in spots and 

 prominences, lines in the spectra of two substarces occur in those positions. 



that in some cases the lines are so near the position of air lines 

 that it has been impossible to make the observation absolutely 

 complete. In other cases the appearance of imperfection arises 

 from the cause that lines which are not seen at the temperature 

 of the arc begin to make their appearance at the temperature 

 of the coil; so that in a case like that at wave-length 5017, for 



