480 Intelligence and Miscellaneous Articles. 



it ; and I show that it would suffice if there were 1 kilogr. of matter 

 in vapour in 700 thousand millions of cubic metres — in other words, 

 that the density would be 0-000 000 000 001 43 kilogr. It will be 

 seen that we are far from the reduction to the 2 fl^ , and even 

 to the millionth assumed by Mr. Siemens. If, instead of taking 

 account only of the resistance opposed by such a gas to the motion 

 of our planet, we direct our attention to the consequences which 

 its existence would have upon that of our atmosphere, we find that, 

 unless we multiply our 700 thousand millions of cubic metres by 

 10,000, and reduce the density sought for to 0-000 000 000 000 0001 

 kilogr., our atmosphere would be in a few moments swept away by 

 the pressure exerted above by the interstellar gas. 



M. Faye is perfectly justified in saying that it is not such or 

 such a degree of rarefaction, but that it is the vacuum {of matter, of 

 course) that the astronomer requires to ensure the stability of the 

 movements that his analysis shows. This vacuum no doubt upsets 

 the doctrine, supposed to be so undeniable, which ascribes all the 

 phenomena of the physical world to movements and collisions of 

 material atoms independent of each other. One day or another, 

 no doubt, this doctrine Avill have to give up its existence, and its 

 defenders will have to resign themselves to admit in the physical 

 world something more than matter in motion. In a remarkable 

 letter to Bentley, Newton said that one must be destitute of all 

 aptitude for a sei'ious philosophical discussion to suppose that 

 between two bodies which seem to attract each other at an 

 unlimited distance, there is not something which establishes this 

 relation ; but, he adds immediately, is this intermediary material 

 or immaterial ? This I leave to the reader to decide. With that 

 great genius undoubtedly there was no uncertainty upon this latter 

 point ; but, perhaps justly, he refrained from putting before his 

 contemporaries a solution which might have seemed incomprehen- 

 sible to them, as it still is, apparently, to so many minds of the 

 present day. — Comjites Rendus, November 6, 1882, p. 812. 



EEPLY TO M. FAYE S OBJECTIONS TO MR. C. W. SIEMENS S THEORY 

 OF THE SUN. BY C. W. SIEMENS. 



M. Faye, while approving, generally, of the physical part of my 

 investigations, questions their application to astronomy, and for 

 the following reasons : — 



1. That the presence of a universal gaseous medium at a pressure 

 of yyVo atmosphere would oppose an excessive resistance to the 

 movements of the planets ; 2. That this vapour, thus distributed, 

 would be gradually attracted towards the sun and would tend to 

 augment its mass considerably. 



Allow me to point out, as regards, in the first place, the second 

 of M. Faye's objections, that the degree of diffusion supposed by 

 me is such as may ensure the permanence of the statical equilibrium 

 between the forces of expansion and diffusion on the one hand, and 



