182 



Mr. J. Norman Lockyer. 



Applying this method of separation, some of the typical stars given 

 on the maps exhibit the following characteristics, those of equal tem- 

 perature, as determined by the metallic lines, being placed on the 

 same horizon. 



Ascending Arm. 



Migel : — 



1. Long continuous spectrum. 



2. Hydrogen lines moderately thick. 



3. Metallic lines of moderate inten- 



sity and thickness. 

 Cleveite gas lines of moderate in- 

 tensity. 



y Cygni .— 



1. Considerable continuous absorp- 



tion in ultra-violet. 



2. Hydrogen lines relatively thin. 



3. Metallic lines of moderate inten- 



sity. 



£ Pegasi: — 



1. Strong continuous absorption in 



violet. 



2. Metallic lines thick. 



Descending Arm. 



y Lyra : — 



1. Continuous spectrum probably a 



little longer than in Eigel. 



2. Hydrogen lines very thick. 



3. Metallic lines weak and thin. 



4. Cleveite gas lines very weak. 



Castor : — 



1. Very little continuous absorption 



in ultra-violet. 



2. Hydrogen lines relatively very 



thick. 



3. Metallic lines relatively feeble. 



Arcturus : — 



1. Little continuous absorption in 



violet. 



2. Metallic lines of moderate thick- 



ness. 



General Conclusion as to Spectroscopic Differences on the Two Sides of 



the Curves. 



The facts thus brought together indicate that at each of three very 

 distinct stages of temperature there are two groups of stars showing 

 spectroscopic differences. Generalising from these, it may be stated 

 that stars at about the same temperature, as judged by the iron lines 

 on the ascending side of the curve, differ from those on the descending 

 side. 



(1) In the greater continuous absorption in the violet or ultra- 

 violet, especially at the lower stages of temperature. 



(2) In the relative thinness of the hydrogen lines at the higher 

 stages of temperature. 



(3) In the greater intensity and thickness of the metallic lines, 

 whether of low or high temperature. 



(4) In the relatively greater thickness of the lines of the cleveite 

 gases at these stages of temperature in which they appear. 



