A/A' WILLIAM SIEMENS, F.R.S. 431 



llame at a point where both their density and temperature had 

 reached the necessary elevation to induce combustion, each com- 

 plete cycle taking, however, years to be accomplished. The resulting 

 aqueous vapour, carbonic anhydride and carbonic oxide, would 

 be drawn towards the equatorial regions, and be then again pro- 

 jected into space by centrifugal force. 



Spare would, according to these views, be filled with gaseous 

 <mpounds in process of decomposition by solar radiant energy, 

 and the existence of these gases would furnish an explanation of 

 the solar absorption spectrum, in which the lines of some of the 

 substances may be entirely neutralised and lost to observation. As 

 regards the heavy metallic vapours revealed in the sun by the 

 spectroscope, it is assumed that these form a lower and denser 

 solar atmosphere, not participating in the fan-like action which is 

 supposed to affect the light outer atmosphere only, in which 

 hydrogen is the principal factor. 



Such a dense metallic atmosphere could not participate in 

 the fan action affecting the lighter photosphere, because this is 

 only feasible on the -supposition that the density of the in-flowing 

 current is, at equal distances from the gravitating centre, equal or 

 nearly equal to the outflowing current. It is true that the products 

 of combustion of hydrogen and carbonic oxide are denser than their 

 constituents, but this difference may be balanced by their superior 

 temperature on leaving the sun, whereas the metallic vapours 

 would be unbalanced, and would therefore obey the laws of gravi- 

 tation, recalling them to the sun. On the surface of contact 

 between the two solar atmospheres intermixture, induced by fric- 

 tion, must take place, however, giving rise perhaps to those vortices 

 and explosive effects which are revealed to us by the telescope in 

 the intermediate or stormy region of the sun, and which have been 

 commented on by Sir John Herschel and other astronomers. Some 

 of the denser vapours would probably get intermixed and carried 

 away mechanically by the lighter gases, and give rise to that 

 cosmic dust which is observed to fall upon our earth in not 

 inappreciable quantities. Excessive intermixture would be pre- 

 vented by the intermediary neutral atmosphere, the penumbra. 



As the whole solar system moves through space at a pace 

 stimated at 150,000,000 of miles annually (being about one- 

 fourth of the velocity of the earth in its orbit), it appears possible 



