COMETS, THE SOLAR CORONA, AND THE AURORA. 53 



VI. The Tails of Comets, the Solar Corona, and the Aurora, 

 considered as Electric Phenomena. Part II. By Pro- 

 fessor Osborne Reynolds, M.A. 



Read February 7th, 187 1. 



In the paper which I read before this Society on the 29th 

 of November last, I endeavoured to show that it is pro- 

 bable that these phenomena are a species of that action 

 known as the electric brush, taking place in the medium 

 which fills space, be it ether, or simply gas, or both. The 

 reasoning I made use of was essentially a fortiori. I 

 pointed to the fact that the electric brush as seen in the 

 Geissler tubes exhibits similar appearances, and that at 

 the times of greatest display on the part of comets and 

 the aurora similar conditions are present, such as a change 

 in the action of the sun, conditions which, to say nothing 

 more, are favourable to electric disturbance. I purposely 

 avoided all attempts to explain how the brush may be 

 produced, feeling that it was sufficient to point to the 

 aurora, which is universally admitted to be electrical, as 

 a proof that such phenomena do exist, even if we cannot 

 explain how. This proof, however, is perhaps not quite 

 satisfactory. In order that it might be complete, the other 

 phenomena would have to be produced in the same way as 

 the aurora; and this, although possible, is not necessary. An 

 assumption which is commonly made respecting the phe- 

 nomena of the aurora cannot be made with respect to the 

 others. This assumption assigns the two magnetic poles 

 of the earth as the two electrodes between which the 

 electric discharge takes place which forms the aurora 

 borealis and the australis. If this assumption be main- 

 tained, some other explanation must be found for the 

 manner in which electricity may form the tails of comets 



