404 W. A. Norton — Physical Constitution of the Sun. 



would naturally happen. After a certain amount of the solar 

 vapors have escaped, contiguous envelopes might interpenetrate 

 each other more or less. What it is especially important to 

 observe, is, that throughout the whole dej^th intercepted hetween 

 each envelope, and the outer limiting surface, A, of the vapor of 

 greatest atomic weight, every atom of the substance of which the 

 envelope is composed, that may chance to be present, is urf^ed up- 

 ward by a force of repulsion. If, as we must suppose, the rise 

 of the solar vapors from the surface, A, continues for an indefi- 

 nite time, the interpenetration of contiguous envelopes would 

 increase, and eventually a condition of equilibrium would be 

 attained ; if the sun's temperature remained the same. But if 

 this temperature were to increase, as it must down to a certain 

 epoch in the process of consolidation, the process above indi- 

 cated would be continually renewed. It is still more important 

 to observe, that if there were any cause in operation withdraw- 

 ing continually at short intervals a portion of one or more oi 

 these rising vapors, a statical equilibrium would not be reached ; 

 and it would be permanently true that /or every such vapor there 

 would be a region of repulsion, as above stated, extending from its 

 envelope down to the outer limit, A, of the vapor of greatest atovw 

 weight. Throughout this region the vapor would be perpetually 

 rising, taking the place of that which is withdrawn, and so 

 maintaining a dynamical equilibrium. The depth of tks region 

 would be the greatest for hydrogen, the outermost gas (unless 

 there is some solar vapor of less atomic weight than hydroefrtii. 

 Now it is easy to see that a certain physical_ cause tendui- 

 produce such results, must come into operation at some - 

 of the sun's process of consolidation. As conceived b} 

 the cooling going on at the outer surface must eventually ' _ 

 the temperature there down to the point at which the vajA ^ 

 having the highest affinity for oxygen will undergo comuu= 

 tion. The products of such combustion, being compounci m 

 cules, will have a greater weight in comparison with tue reu 

 sion to which they are exposed, than the simP^^ folecui^ 

 before the combination took place, and hence they will dea ^^ 

 more or less rapidly, into the depths of the pl^o^^^^P^^.*^ | ^f its 

 all appearance the sun is now passing through this pe;';°^.,^^^^ia. 

 physical history, as supposed by Faye ; and m the -_ 

 tions" which give to the sola^ disc a mottled appe^^anc^ 

 (Herschel's "subsiding chemical precipitates, ) }^® P ^^ppgr 

 discern the products of the combustion occurring in ^^J^^ J ^^. 

 photosphere and determining its outer limit, m the a ^ ^ ^^^ 

 scending. The continual upward flow from the depxu^., 

 photosphere, of the hydrogen, oxygen, and the Ugliteyi^^;.^,,, 

 vapors, will bring about the necessary mtermixtuie o -^.^^^^.| 

 with the other vapors. This must occur below tne 



