58 



Mr. J. N. Lockyer. On the Classification [Apr. 12, 



of course there must be some continuous absorption in the blue. This 

 is perhaps the most highly- developed normal spectrum-giving condi- 

 tion ; 44, 45, 55, 60, 65, 86, 92, 278 are examples. 



The Paling of the Fluting s. 



Subsequently, the spectra are in all cases far from being discon- 

 tinuous, and the flutings, instead of being black, are pale. Thus, 

 while the bands are dark in the stars we have named, they are not 

 so dark in a. Orionis. Here, in short, we have a great distinction 

 between this star and a. Herculis, o Ceti, K, Lyree, and p Persei. 



Obviously this arises from the fact that the average distances 

 between the meteorites have been reduced ; their temperature being 

 thereby increased as more collisions are possible, the vapours are 

 nearly as brilliant as the meteorites, and radiation from the inter- 

 spaces cloaks the evidences of absorption. Nor is this all: as the 

 meteorites are nearer together, the area producing the bright flutings 

 of the carbon is relatively reduced, and the bands 10 and 9 will fade 

 for lack of contrast, while 8 and 7 will fade owing to the increased 

 temperature of the system generally carrying the magnesium absorp- 

 tion into the line stage ; b is now predominant (see 102, 157, 163, 

 114, 125, 135). 



Under these conditions the outer absorbing metallic atmosphere 

 round each meteorite will in all probability consist of Mn and Fe 

 vapours, and in this condition the masking effect will least apply to 

 them. This is so (114, 116) ; they remain dark, while the others are 

 pale. 



Here w r e have the indication of one of the penultimate stages 

 already referred to. 



Phenomena of Condensation. 



Dealing specially with the question of condensation, — I have 

 already referred to possibly the first condition of all, recorded by 

 Duner in the observations now discussed — I may say that the first 

 real and obvious approach to it perhaps is observed when all, or 

 nearly all, except 9 and 10 of the flutings are wide and dark. The 

 reasons will be obvious from what has been previously stated. Still 

 more condensation will give all, or nearly all, the bands wide and 

 pale, while the final stage of condensation of the swarm will be 

 reached when all the bands fade and give place to lines. We have 

 then reached Class II (107, 139, 168, 264) ; 2 and 3 should be and 

 are perhaps the last to go (203). 



