A VOYAGE TO THE SUN. 49 



a solar aurora. How the electrical action causing such 

 an aurora is excited, seems open to question : though 

 the facts to be presently described suggest a probable 

 explanation. But after what we had now seen, I had 

 myself very little doubt that electricity is the main 

 cause of the phenomenon. 



Passing Mercury (some twenty millions of miles on 

 our right as we crossed his orbit) we began to draw so 

 close towards the sun, that many of the features shown 

 by good telescopes could be clearly recognized. His 

 spots already presented a striking appearance ; but we 

 were most interested at this stage of our progress by 

 the aspect of the coloured prominences and sierra. 

 Nothing more beautiful can be conceived than the 

 fringe of coloured light surrounding the intensely 

 white orb of the sun. The varieties of colour men- 

 tioned above seemed now to be multiplied fifty-fold. 

 There are no terms by which the beauty of the scene 

 can be described. To say that the sun appeared like 

 a shield of glowing silver set round by myriads of 

 sparkling jewels of all the colours of the rainbow, is as 

 far from the truth as though one should compare the 

 hues of the most brilliant fireworks with the sombre 

 tints of autumn foliage. 



The glowing inner atmosphere amidst which these 

 prominences displayed their splendours, had now, owing 

 to our near approach, increased very largely in apparent 

 extent. We could distinguish many varieties of colour 

 and brightness within its limits, and from time to 

 time radial striations appeared over the solar spot 



