Thomson. 



Phil. Mag. Ser. 6, Vol. 40, PL IV. 



No. I 



Comparison 

 Spectrum, H 2 

 & He mixed 



No. 2 



H* CO band Hg Hy 

 4835 4358 



All lines in Xo. '2 not otherwise marked belong to tin 

 second spectrum of hydrogen. 



