SIR NORMAN LOCK YER 37i 



Now, can we get more information concerning this association of 

 certain gases and metals ? In laboratory work it is abundantly recog- 

 nized that all meteorites (and many minerals) when slightly heated 

 give out permanent gases, and under certain conditions the spectrum 

 of the nebulae may in this way be closely approximated to. I have not 

 time to labor this point, but I may say that a discussion of all the 

 available observations to my mind demonstrates the truth of the 

 suggestion, made many years ago by Professor Tait before any spec- 

 troscopic facts were available, that the nebulae are masses of meteorites 

 rendered hot by collisions. 



Surely human knowledge is all the richer for this indication of the 

 connection between the nebulae, hitherto the most mysterious bodies 

 in the skies, and the "stones that fall from heaven." 



CELESTIAL EVOLUTION 



But this is, after all, only a stepping stone, important though it be. 

 It leads us to a vast generalization. If the nebulae are thus composed, 

 they are bound to condense to centers, however vast their initial pro- 

 portions, however irregular the first distribution of the cosmic clouds 

 which compose them. Each pair of meteorites in collision puts us 

 in mental possession of what the final stage must be. We begin with 

 a feeble absorption of metallic vapors round each meteorite in colli- 

 sion; the space between the meteorites is filled with the permanent 

 gases driven out farther afield and having no power to condense. 

 Hence dark metallic and bright gas lines. As time goes on the former 

 must predominate, for the whole swarm of meteorites will then form 

 a gaseous sphere with a strongly heated center, the light of which 

 "will be absorbed by the exterior vapor. 



The temperature order of the group of stars with bright lines as 

 well as dark ones in their spectra has been traced, and typical stars 

 indicating the chemical changes have been as carefully studied as 

 those in which absorption phenomena are visible alone, so that now 

 there are no breaks in the line connecting the nebulas with the stars 

 on the verge of extinction. 



Here we are brought to another tremendous outcome — that of the 

 evolution of all cosmical bodies from meteorites, the various stages 

 recorded by the spectra being brought about by the various condi- 

 tions which follow from the conditions. 



