SINGULAR ATMOSPHERIC PHENOMENON. 197 



and Captain Lyon says that the sudden glare and 

 rapid bursts of those wondrous showers of fire make 

 it difficult to believe that their movements are wholly 

 without sound. Yet such would seem to be the 

 case, for the same authority tells us that he stood 

 on the ice for hours listening intently and could 

 hear nothing. He was thoroughly convinced that no 

 sound proceeds from the aurora, and most intelligent 

 voyagers support him in this opinion. 



That the aurora dims the lustre of the stars 

 seen through it, is a fact which was ascertained 

 clearly by the same gentleman ; and that it moves 

 in a region beyond the clouds is also evident from 

 the fact that when the latter covered the sky the 

 aurora disappeared. 



But some of the most singular appearances of the 

 sea and sky in the polar regions are presented in 

 summer. During that season the perpetual presence 

 of the sun and the large tracts of ice floating about 

 on the sea exert their opposing influences so as to 

 produce the most astonishing results. 



One part of the sea being covered with ice, pro- 

 duces a cold atmosphere; another part being free 

 from ice, produces a warmer atmosphere. Refrac- 

 tion is the result of viewing objects through those 

 different media, and very curious appearances follow. 

 When Scoresby was in Greenland a singular atmos- 

 pheric phenomenon occurred, whereby he became 

 aware of the approach of his father's ship some time 

 before it rose above the horizon. He had reached 



