CONDITION OF THE LARGER PLANETS. 177 



the valuable opportunities for observation during the 

 last quarter of a century were frittered away in abso- 

 lutely unnecessary attempts to prove the corona to be 

 what mathematical considerations had already shown 

 that it is a solar appendage. 

 ;** Longman's Magazine for December 1882. 



CONDITION OF THE LARGER PLANETS. 



M. VOGEL'S researches into the spectra of the planets 

 were regarded by him as affording evidence unfavour- 

 able to the opinion that the planets Jupiter and Saturn 

 are still so intensely hot as to shine in some degree 

 with inherent light. Although it is not at all ne- 

 cessary for the general theory which I have advocated 

 respecting the condition of the larger planets that 

 any portion of their lustre should be regarded as in- 

 herent, yet as Vogel's conclusion does bear to some 

 degree on one of the arguments which have been urged 

 in favour of this theory, the opportunity seems con- 

 venient for summing up these arguments and discussing 

 briefly the considerations on which M. Vogel bases his 

 objection. 



I would remark at the outset that I do not by any 

 means share the opinion of some who, in dealing with 

 this question, and other questions of a like nature, 

 have said that it matters very little what theory is 

 adopted so that it is a convenient working hypothesis, 

 a string, so to speak, on which to thread the observa- 



III. 3f 



