246 FKOM NEBULA TO NEBULA 



sunk toward her center and only froth and scum re- 

 mained to blanket her. 



Though I have spoken of the sun's strata, both in 

 discussing his differential rotations and the chemical con- 

 stitution of his shell, and shall yet continue so to speak, 

 yet I wish the reader to understand that there are no 

 sharp lines of demarcation between them, but that the 

 changes up and down, though certain and pronounced, 

 melt imperceptibly into each other. The reason lies, of 

 course, in the great variety of the natural chemical ele- 

 ments and compounds, and in their abundance in the 

 solar economy. Assuming that the graded temperatures 

 of the shell, level by level, are invariable, and that the 

 pressures are equally so, it follows that every element 

 and compound regularly explodes every time it reaches 

 its particular critical depth. Such explosions necessarily 

 cause eruptions through the photosphere, giving rise to 

 jets, geysers, fountains, or prominences, whichever the 

 reader may think best to call them. In proportion to 

 their deep-seatedness and severity, these explosive gases 

 not only change places themselves, but they carry before 

 them in their outward rush great quantities of debris 

 from the intervening layers to greater or less heights 

 beyond the photosphere, whence, being normally con- 

 densed and turned back by the cosmic cold, they rain 

 down upon the photosphere in a ceaseless hail of slag 

 and cinder only to begin the same process over again. 



Briefly, then, the solar process consists in the con- 

 tinuous explosive conversion of the sun's interior sub- 

 stances into gases by virtue of the pressure of the super- 

 incumbent layers falling toward his center, the space 

 allowing for such fall being vacated by the said gases, 

 which rise to the surface upon the wings of their own 

 explosive force, there render up their heat, condense, and 

 regain their original energy of position as part of the 

 great solar press an unending cycle of mechanical com- 

 bustion and gravitational resynthesis. 



This cyclical process of converting gravity into heat 

 and heat into gravity again, finds a remarkable parallel 

 in the terrestrial transformation of water into vapor, 



