384 AN AURORA BOREALIS, 



of the earth ; or, perhaps, round its magnetic 

 pole. The streamers, in some of them that I 

 have observed, have had a lateral motion, a cir- 

 cumstance that attended the streamers of last 

 night. And I find that an Aurora which I ob- 

 served on the evening of September 3rd, 1839, 

 in London, was seen in America on the same 

 night, and, by their time, about the same hour, or 

 somewhat earlier, so that it had travelled westerly 

 (the direction in which the streamers moved as 

 seen in London) at the rate of about 18° or 20° 

 per hour, calculating from the time of its com- 

 mencement here to its commencement in America: 

 or, between nine o'clock in London to eight 

 o'clock at Princeton. 



I could not, however, from this solitary instance, 

 suppose that the Aurora Borealis invariably travels 

 in this direction, because I have seen streamers 

 which travelled easterly ; but those of last night 

 travelled westerly. Nevertheless, if it can be pro- 

 ved that the meteor travels round some spot in high 

 northern regions, or round the pole itself, an im- 

 portant step towards ascertaining the real cause of 

 its appearance would be gained. That the Aurora 

 Borealis is seen in widely difierent longitudes, is a 

 fact long ago ascertained ; and T cannot help think- 



