56 Mr. J. Norman Lockyer. On the Appearance of the 



These differences are shown on the map, and they fully accord 

 with the laboratory work, which indicates that helium and gas X 

 are to be regarded as distinct substances. 



Comparison of the Lines of the Subordinate Series. — In the above 

 investigation it has been found that, in tracing the progress of gas X 

 through the stars of increasing and decreasing temperature in the 

 photographic region, the relative intensities of the lines of the 

 different series are changed from those tabulated in the laboratory. 

 The lines of the principal series, as indicated by the line at 3964*9, 

 are no longer the strongest, but become of secondary importance as 

 regards intensity, whilst the first subordinate series now takes the 

 pre-eminent position, and the second subordinate series nearly dis- 

 appears altogether, being only represented very feebly near the point 

 of highest temperature. 



In the following tables, drawn up by Mr. Shackleton, will be found 

 a statement of the relative intensities of the principal, first sub- 

 ordinate, and second subordinate series of gas X and helium. 



Relative Intensities in Stars of increasing Temperature of the Lines 

 in the principal and subordinate Series of Gas X. 



Star. 



Principal series 

 (A 3964-9). 



1st subordinate 

 series 

 (A 4388-1). 



2nd subordinate 

 series 

 (44377). 





5 



7 



1 



Eigel 



4 



3 







2 



? trace 







2 



1 





















Relative Intensities in Stars of increasing Temperature of the Lines 

 in the 1st and 2nd subordinate Series of Helium. 





1st subordinate 



2nd subordinate 



Star. 



series 



series 





(A 4471*6), 



(A 4121-0). 





10 



4 



Eigel 



6 



2—3 





2 



1 





1 



1—2 















