Intelligence and Miscellaneous Articles. 481 



the attraction towards the sun and the celestial bodies on the other. 

 If no such equilibrium were established, M. Faye's objection would 

 at once upset my theory. I am, moreover, inclined to admit that 

 if Mariotte's law with regard to the tension of gases could be applied 

 indefinitely, the pressure of the interplanetary gaseous medium 

 would be reduced almost beyond any thing of which we can form 

 an idea ; but it seems to me, from considerations drawn from the 

 dynamical theory of gases, and from the manner in which, as 

 demonstrated by Mr. Crookes, gases behave when rarefied to an 

 extraordinary degree in tubes — it seems to me, I say, that at least 

 there exists no reason a priori why this law should be extended 

 rigorously to vapours beyond the confines of om' atmosphere and 

 of that of the Sun. 



As regards M. Faye's first objection, I admit that a density of 

 a oVq - atmosphere would have the consequences which he so correctly 

 establishes ; and I remember having said (see ' Proceedings of the 

 Royal Society,' p. 395) that assuming as demonstrated the results 

 of my experiments on the dissociation of vapours by the solar 

 energy, and that stellar space is filled with vapour at a pressure 

 not exceeding the limit of yw&G atmosphere, which corresponds to 

 the highest rarefaction that I was able to obtain in my experiments, 

 a dissociation of this cosmical vapour must ensue by the radiation 

 of the Sun. It must nevertheless be remarked that this obser- 

 vation only relates to the physical phenomena submitted to my 

 experiments, and that it is evident that if, the dissociation of aqueous 

 vapour and of carbon-compounds is effected by the direct radiation 

 of the sun at so high a pressure as xuVo" atmosphere, it would with 

 still more reason be effected in the much more rarefied medium. 



In another passage of my memoir (p. 397), when I apply my 

 hypothesis to comets, I assume that, even at their perihelion, they 

 represent a vapour-medium with a density of only g-^rtr atmosphere, 

 and that this density suffices to give rise to incandescence by com- 

 pression. This supposition proves, at any rate indirectly, that I 

 regarded stellar space as filled with vapour at a pressure much 

 below 3 o 1 ^ $ atmosphere, while still speaking of this medium (in the 

 absence of all data of experiment and observation) as in an extremely 

 rarefied state, without fixing any limit of this rarefaction. 



Since then new facts of observation have tended to confirm my 

 hypothesis of a stellar space filled with rarefied matter analogous 

 to that which we can actually produce in our vacuum-tubes. The 

 equatorial prolongations of the solar atmosphere observed in America 

 during the eclipse of 1859, seem to demonstrate the existence of 

 matter extending from the Sun for several millions of leagues, and 

 rendered visible, no doubt, by solid particles, illuminated partly by 

 the reflection of the solar light, and partly by discharges of elec- 

 tricity towards the Sun. 



My hypothesis has found a still more direct confirmation in the 



remarkable spectroscopic investigations communicated by Capt. 



Abney to Section A of the British Association in the month of 



August last, which demonstrate that carbon -compounds, probably 



Phil. Mag. S. 5. Vol. 14. No. 90. Dec. 1882. 2 K 



