Theory of Solar Action. 



405 



C0 3 . The specific gravity of the vapour of lithic oxide would 

 be 15, that of beryllia probably 12' 6, of magnesia 20, of sodic 

 oxide 31. According to these considerations the various sub- 

 stances would be projected to the following proportional 

 distances : — 





Metal. 



Oxide 



Aqueous vapour . . 



100 



100 



Carbon dioxide . . . 



41 



41 



Lithium 



129 



60 



Beryllium .... 



98 



71 



Sodium 



39 



29 



Magnesium .... 



. 37 



45 



Aluminium .... 



. 33 



18 



Calcium 



22 



32 



It would thus appear that the composition of the stellar 

 atmosphere must be far more complicated than is supposed, 

 and the possible existence of an inner atmosphere seems prob- 

 lematical. 



There is only one other point to refer to. The researches 

 of spectroscopy and the revelations of the telescope have 

 revealed to us the fact that our sun is only one of an innu- 

 merable number of similar bodies. A theory, then, to be 

 complete, ought to account for the action of all. Moreover 

 Dr. Huggins has shown that the fixed stars may be divided 

 into classes according to the spectra which they emit. Thus 

 we have every gradation, from the spectrum of a white or 

 bluish-white star like Sirius, passing through a yellowish one 

 like our sun, up to a reddish one like Arcturus. Now, since 

 we have the same atmosphere supplying all and the same 

 cause producing motion, it is difficult to see how these differ- 

 ences are to be accounted for. Dr. Huggins has supposed 

 these observations to show that the stars are of different ages — 

 some being in the height of their energy and thus producing 

 spectra in which the shorter waves predominate, while others 

 have passed this stage and are yielding radiations of longer 

 period. Dr. Siemens mentions that, as the whole solar system 

 is moving through space at a very great velocity, the nature of 

 the solar fuel may vary at different times, and thus a difference 

 in the energy of the action may be caused. But any difference 

 which may exist would be rapidly removed by the action of 

 gaseous diffusion, which would rapidly cause the universal 

 atmosphere to become practically homogeneous. Again, if the 

 fuel varies from time to time, how is it that we find the spectra 

 of the various stars to be constant ? They would under these 

 circumstances, we are inclined to imagine, present none of 

 those constant characters which Dr. Huggins has established. 



Phil. Mag. S. 5. Vol. 15. No. 96. June 1883. 2G 



