THE FUEL OF THE SUST. 8? 



depending upon intensity, those of sunlight upon quantity of 

 light. 



The flame that roars from the mouth of a Bessemer convert- 

 er has but small intrinsic brilliancy, far less than that of an 

 ordinary gas name, a* may be seen by observing the thin waifs 

 that sometimes project beyond the body of the flame. Never- 

 theless, its radiations are so effective that it is a painfully daz- 

 zling object even in the midst of sunny daylight ; but then we 

 have here not a hollow flame fed only by outside oxygen, but 

 a solid body of flame several feet in thickness. Even the pallid 

 carbonic acid flame which accompanies the pouring of the 

 spiegeleisen has marvellous illuminating po\ver. 



The reader will now be able to understand my explanation 

 of the sun spots, of their nucleus, umbra, and penumbra. 

 From what I have stated respecting the planetary disturbances 

 of the solar rotation, the photosphere should present all the 

 appearances due to the movements of a fiery ocean, raging and 

 seething in the maddest conceivable fury of perpetual tempest. 

 If the surface of a river flowing peacefully between its banks is 

 perforated with conical eddies whenever it meets with a pro- 

 jecting rock or obstacle, or other agency which disturbs the 

 regularity of its course, what must be the magnitude of the 

 eddies in this 02eau of flame and heated gases, wli3n stirred to 

 the lowest depths of its vast profundity by the irregular reel- 

 ing of the solar nucleus within ? Obviously, nothing less than 

 the sun-spots ; those mighty maelstroms into which a world 

 might be dropped like a pea into an egg-cup. 



When the photosphere or shell of combining gases is thus 

 ripped open, the telescopic observer looks down the vortex, 

 which, if deep enough, reveals to him the inner region of 

 dissociated gases and vapors. But these have the opposite 

 property to that which I have shown to. belong to flame ; they 

 are opaque to their own special radiations, while the flame is 

 transparent to the light of the inner portions of itself. Thus, 

 the dissociated interior of the solar envelope, though abso- 

 lutely white-hot, will be comparatively dark (direct experiment 

 h is proved that the darkness of the spots is only relative). 



The sides of the vortex funnel will consist of a mixture of 

 dissociated gases, flaming gases, and combined gases, and will 

 thus present various thicknesses of flame, and thereby display 

 the various shades of the penumbra. Space will not permit me 

 here to follow up the details of this subject, as I have done in 

 the original work, where it is shown that if the telescope had 



