On the Corona of the Sun. 131 



nearer planets Venus and Mercury, exert an influence on the electri- 

 fied and attenuated matter of the corona. 



The elaborate researches of Mr. De la Rue and Professor Balfour 

 Stewart appear to show an influence exerted by Venus and Mercury 

 upon the solar regions of spot action. 



We know nothing of the electric distribution on Venus and on 

 Mercury, but it seems more than probable that these bodies, as well as 

 the meteor-swarms nearer to the sun, have an influence in determin- 

 ing the mode of outflow of the electrified coronal matter in the direc- 

 tions in which they happen to be. The influence may be one of 

 attraction, giving rise to coronal extension or rays from the corona, 

 or to repulsion, in which case we might have what appears to us as a 

 rift directed towards the body. 



We have not sufficient data to furnish certain information on this 

 point, but it may be of interest to quote the following sentences from 

 Mr. Trouvelot's Report of the Eclipse of 1878*:— 



" There is a fact connected with this eclipse, which, if not due to a 

 singular coincidence, would seem to point to some attractive action of 

 the planets on the solar atmosphere (corona). On the day of the 

 eclipse Mercury and Venus were in almost opposite points of their 

 orbits, with the sun between and almost on a line with them, while 

 the Earth on the same day was in a part of its orbit which formed 

 the apex of an equilateral triangle having for base the line joining 

 Mercury and Venus. Knowing this, it is perhaps singular, and any- 

 how very remarkable, to see that the eastern wing of the corona was 

 directed on a straight line to Mercury, while the western appendage 

 was directed on a straight line to Venus. The coincidence was still 

 greater. As in regard to the sun, the two planets were not exactly 

 on the same line, Mercury being a little to the north, while V enus 

 was a little to the south of the ecliptic ; the solar appendages have 

 shown the same peculiarity, their axes being a little inclined to each 

 other." 



I may say that the inclination of the axes of coronal extensions on 

 the two sides of the sun may be seen in the photographs of this 

 eclipse. It should be stated that Professor JSTewcomb, who observed 

 the coronal extension towards Venus, says: — "I tried to judge 

 whether the western one (ray) pointed towards the planet Venus, 

 then plainly visible near the horizon. The direction was apparently 

 very slightly below that of the planet." Professor Newcomb's words 

 seem to show that he did not make any allowance for refraction, 

 which would make the planet when near the horizon appear sensibly 

 higher than its true place. 



If sufficient evidence should be forthcoming in the future to estab- 

 lish a sensible influence of the planets upon the corona, we should not 



* Tage 93. 



K 2 



