234 THE POPULAR SCIENCE MONTHLY. 



polar surfaces of the sun to-morrow, be heated by increase in density, 

 and would burst into flame at a point where both their density and 

 temperature had reached the necessary elevation to induce combustion, 

 each complete cycle taking, however, years to be accomplished. The 

 resulting aqueous vapor, carbonic acid, and carbonic oxide would be 

 drawn toward the equatorial regions, and be then again projected into 

 space by centrifugal force. 



Space would, according to these views, be filled with gaseous com- 

 pounds 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 neutralized and lost to observation. As regards the heavy 

 metallic vapors 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 atmos- 

 phere 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 inflowing current is, at 

 equal distances from the gravitating center, equal or nearly equal to 

 the outflowing current. It is true that the products of combustion of 

 hydrogen and hydrocarbon are denser than their constituents, but this 

 difference may be balanced by their superior temperature on leaving 

 the sun, whereas the metallic vapors would be unbalanced, and would 

 therefore obey the laws of gravitation, recalling them to the sun. On 

 the surface of contact between the two solar atmospheres, intermixt- 

 ure induced by friction must take place, however, giving rise to those 

 vortices and explosive effects within the zones of the sun, between the 

 equator and the polar surfaces, to which reference has already been 

 made in this article ; these may appropriately be called the " stormy 

 regions " of the sun, which were first observed and commented upon 

 by Sir John Herschel. Some of the denser vapors would probably get 

 intermixed, be carried away mechanically by the lighter gases, and 

 give rise to that cosmic dust observed to fall upon our earth in not 

 inappreciable quantities, and generally assumed hitherto to be the 

 debris of broken meteorolites. Excessive intermixture between the 

 heat-producing atmosphere and the metallic vapors below appears to be 

 prevented by the existence of an intermediate neutral atmosphere, and 

 called the penumbra. 



As the whole solar system moves through space at a pace estimated 

 at 150,000,000 miles annually (being about one fourth of the velocity 

 of the earth in its orbit), it appears possible that the condition of 

 the gaseous fuel supplying the sun may vary according to its state of 

 previous decomposition, in which other heavenly bodies may have 

 taken part, and whereby an interesting reflex action between our sun 

 and other heavenly bodies would be brought about. May it not be 



