12 



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



stars, the outer constituent of the atmosphere — hydrogen — alone being 

 raised by the friction to brilliant incandescence. 



Another objection we can urge against the old view is that all 

 bodies in the universe cannot be finished suns in the ordinary sense, 

 and that it leaves out of account all possible processes of manufacture, 

 not only of single stars, but of double and multiple systems, at all 

 stages between nebula and sun ; while the new one, by simply changing 

 the unit from the star to each individual constituent, it is hardly too 

 much to say, explains everything, though it is perfectly true that 

 in some of the steps a considerable acquaintance with spectroscopic 

 phenomena is necessary to realise the beauty and the stringency of the 

 solutions. 



The Question of Hydrogen in the Case of Bright-line Stars. 



It may be convenient also that I should summarise the various 

 conditions under which the lines of hydrogen are observed in the 

 meteoritic swarms we are now considering. 



In the " nebulas " we begin with the widest interspaces. Future 

 investigation may, as I have suggested, show that those in which the 

 hydrogen lines are absent are the most widely spaced of all. Be this 

 as it may, it is a matter of common knowledge that in the brighter 

 nebulas, such as that of Orion, to take an instance, we have hydrogen 

 associated with the low-temperature radiation of olivine. That the 

 hydrogen is electrically excited to produce this glow is proved by the 

 fact that the temperature of the meteorites themselves must be very 

 low; otherwise the magnesium would not show itself without the 

 manganese and iron constituents, and the continuous spectrum would 

 be much brighter and longer than it is. 



In the former paper I showed that in my laboratory experi- 

 ments, when the pressure was slightly increased in a tube containing 

 gases obtained from meteorites, the carbon bands began to be visible. 

 We should expect this to happen therefore in a meteor swarm at some 

 point at which the mean interstitial space was smaller than that 

 accompanied by the appearance of the hydrogen lines ; and it would be 

 natural that both should be seen together at an early stage and both 

 feeble, by which I mean not strongly developed, as hydrogen is not 

 strongly developed even in the nebula of Orion, none of the ultra- 

 violet lines being visible in a photograph, while the magnesium 

 line is. 



The association of the low-temperature lines of hydrogen with the 

 flutings of carbon is therefore to be expected, and I shall subse- 

 quently show that we have such an association in the so-called bright- 

 line stars ; and even at a further stage of development, in stars like 

 a Orionis, the hydrogen is still associated with the carbon. 



