XVI.] THE DISTRIBUTION OF CHEMICAL GROUPS OF STARS. 131 



He found that the Milky Way was due to an aggregation of white 

 stars, by which he meant, as we now know, very hot stars, and the 

 hottest of them, that is the gaseous ones, exist more obviously in the 

 Milky Way than do the others. The proportional number of proto- 

 metallic stars in the Milky Way was greater for the fainter stars than 

 for the brighter ones of this kind, and that at once suggests a possi- 

 bility that in the Milky Way itself there is a something which 

 absorbs light ; so that the brightest stars are apt not to be really the 

 brightest, but apparently bright because they have not suffered this 

 absorption, and that those which have suffered this absorption may be 

 very much further away from us than the others of a similar chemistry. 

 He also arrived at this extremely important conclusion, namely, that 

 the metallic stars, that is, stars like our sun, stars more or less in their 

 old age, had no preference for the Milky Way at all, but are equally 

 distributed all over the sky. With regard to the group of stars known 

 by metallic flutings in their spectra, he has no information to give us 

 any more than Duner had, for the reason that their number is small, 

 and they have not yet been completely studied. 



Only last year this inquiry was carried a stage further by 

 Mr. McClean, who not only photographed a considerable number of 

 stellar spectra in the northern hemisphere, but subsequently went to 

 the Cape of Good Hope in order to complete the story with reference 

 to the stars down to the third or fourth magnitude which he could 

 observe there. He was very careful to discuss, in relation to the Milky 

 Way and certain galactic zones, the distribution of the various kinds 

 of stars which he was fortunate enough to photograph. 



He found that if we deal with the gaseous stars the numbers in the 

 north and south polar region are small, and that the numbers nearer 

 the Milky Way are greater, so that finally we can see exactly how these 

 bodies are distributed. If we take the gaseous, that is to say the 

 hottest stars, we find the smallest number in the polar regions ; but if 

 we take the metallic stars we find practically the largest number, at all 

 events a considerable number, in the polar regions. The general result, 

 therefore, is that the gaseous stars are mostly confined to the galactic 

 zones, the proto-metallic stars, that is those down to about 3J mag- 

 nitude, are not so confined. What is also shown is that the metallic 

 fluting stars are practically equally distributed over the polar regions 

 and over the plane of the Milky Way itself ; so that, in that respect, 

 we get for these stars very much the equivalent of the result arrived 

 at by Duner for the carbon stars, that is to say, they have little pre- 

 ference for the Milky Way. 



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