1 87 1.] The Fuel of the Sun. 451 



regions of the sun. None of these could constitute the 

 body of the sun in a solid or liquid state, and subject to the 

 enormous pressure which such a mass must exert upon 

 itself without raising the mean specific gravity vastly above 

 this ; nor is there any other kind of matter with which we 

 are acquainted which could exist within so large a mass in 

 a liquid or solid state, and retain so low a density. 



I must confess that my faith in the logical acumen of 

 mathematicians has been rudely shaken by the manner in 

 which eminent astronomers have described the umbra or 

 nucleus of the sun-spots as the solid body of the sun seen 

 through his luminous atmosphere, and the solid surface of 

 Jupiter seen through his belts, and have discussed the 

 habitability of Jupiter, Saturn, Uranus, and Neptune always 

 on the assumption of their solidity, while the specific 

 gravity of all of these renders this surface solidity a demon- 

 strable physical impossibility. 



If the sun (or either of these planets) has a solid or liquid 

 nucleus, it must be a mere kernel in the centre of a huge 

 orb of gaseous matter, and though I have spoken rather 

 definitely of the solar atmosphere in order to avoid com- 

 plication, I must not, therefore, be understood to suppose 

 that there exists in the sun any such definite boundary to 

 the base of the atmospheric matter as we find here on the 

 earth. The temperature, the density, and all we know of 

 the chemistry of the sun justify the conclusion that in its 

 outer regions, to a considerable depth below the photosphere, 

 there must be a commingling of the atmospheric matter 

 with the vapours of the metals whose existence the spec- 

 troscope has revealed. Some of these must be upheaved 

 together with the dissociated elements of water. They are 

 all combustible, and, with a few exceptions, the products 

 of their combustion would solidify after they were pro- 

 jected beyond the photosphere. Much of the iron, nickel, 

 cobalt, and copper might pass through the fiery ordeal of 

 such projection, and solidify without oxidation, especially 

 when more or less enveloped in uncombined hydrogen. 



It is obvious that, under these circumstances, there must 

 occur a series of precipitations analogous to those from the 

 aqueous vapour of our atmosphere. These gaseous metals, 

 or their oxides, must be condensed as clouds, rain, snow, 

 and hail, according to their boiling and melting points, and 

 the conditions of their ejection. We know that sudden and 

 violent atmospheric disturbance, accompanied with fierce 

 electrical discharges, especially favour the formation of 

 hailstones in our terrestrial atmosphere. All such violence 



VOL. VIII. (O.S.) — VOL. I. (N.S.) 3 N 



