IN THE SOLAR. SYSTEM. 



91 



I am now about to discuss the last of the comctary phenomena which I think admits of 

 explanation by the influence of ether. 



When endeavoring by the aid of h priori reasoning to trace out the course of the grand 

 ethereal currents which circulate through the solar system, I pointed out the necessity for 

 the existence of two currents of ether, which should descend upon the sun's polar regions ; 

 and hinted that analogy justified the belief that the polar currents descend upon the sun's 

 surface in the form of vortices. 



An interesting question naturally associates itself with these views, viz. What effect 

 should be produced upon a comet which passed through the regions where these currents 

 prevail ] 



We will suppose the comet before entering the region to present the normal features of 

 these bodies. If it be furnished with a tail, we will suppose that it is pointed in the 

 direction away from the sun. 



Passing into the vortex, the head of the comet should undoubtedly feel the effect of the 

 downward current before the distant portions of the tail. We might, therefore, expect to 

 see the old tail, while pursuing its trajectory, gradually leave the head, and a new tail, 

 entangled by the descending current of ether, carried in a direction obliquely towards the 

 sun. 



In 1G07 Halley's comet passed its perihelion October 26th. "The tail was visible from the time the comet was 

 first perceived by Kepler, on the 16th September, until the 12th of the following month." (Hind, Comets, p. 36.) 



In 1759 Halley's comet passed its perihelion March 12th. Pingre says, " La Nux did not content himself with 

 obsorvim>' the nucleus; he was attentive also in measuring the length of the tail. He found it on the 21st April, 

 8 degrees • the 28th April, 25 degrees; May 1st, 33 to 34 degrees; May 5th, 47 degrees. It lessened afterwards. 

 May 14th, it was only 19 degrees." (Cometographie, vol. ii, p. 65.) 



In 1835 Halley's comet passed its perihelion November 15th. Sir John Ilerschcl says: " It was not before 

 the 2d October that the tail began to bo developed, and thenceforth increased pretty rapidly, being already 4° or 



5° long on the 5th." 



" It attained its greatest length (about 20°) on the 15th October. From that time, though not yet arrived at 

 its perihelion, it decreased with such rapidity that already, on the 29th, it was only 3°, and on November 5th, 2J° 

 in length. There is every reason to believe that before the perihelion, the tail had altogether disappeared, as, 

 though it continued to be observed at Pulkowa up to the very day of its perihelion passage, no mention whatever 



is made of any tail being seen." 



"Profess.,.- Strove says, the nucleus appeared like a stream of fire which issues from the cannon's mouth after 

 discharge, when the sparks are driven back by a violent wind." (Hind, p. 48.) 



"As the comet receded from the sun, the coma speedily disappeared, as if absorbed into the disc, which, on the 

 other hand, increased continually in dimension. . . • While this increase of dimension proceeded, the form of 

 the disc passed, by gradual and successive additions to its length, in the direction opposite to the sun, to that of a 

 paraboloid. ... It is evident that had this process continued with sufficient light to render the result visible, a 

 tail would have been ultimately reproduced, but the increase of dimension being accompanied with diminution of 

 brightness, a short, imperfect, and, as it were, rudimentary tail only, was formed, visible as such, for a few nights, 



