.] 



PIONEERING DIFFICULTIES 



23 



merits in the laboratory had given a definite result with regard to the 

 spectrum of a metal in this way, I proceeded to study the sun with 

 a view of determining how that metal behaved in the sun. 



This involved, first, photographs of the solar spectrum with its dark 

 lines, photographic comparisons of these dark lines with the bright 



a o 



* PH 



1 J 



-3 * 



bC 

 O 



I 



lines constituting the spectra of the metallic elements. This enabled 

 us to compare the total light given by each light source with the light 

 received from all parts of the sun indiscriminately. 



