450 APPENDIX. 



by the laws of electric phenomena, an opposite electrical state 

 in that portion nearest it ; and these opposite electricities would 

 instantly attract each other, fly together, burst forth in fire, 

 and become neutralized. If there should be a plane in which 

 such thin clouds are formed, the subversion and re-establish- 

 ment of the balance of electricity being thus begun would be 

 rapidly propagated throughout the whole of this space, and 

 produce that rapid, undulatory motion which we observe in 

 the Aurora Borealis." 



In considering the subject of the Aurora Borealis, my at- 

 tention was drawn to a fact which does not appear to me to 

 have been hitherto noticed. I allude to the direction in which 

 the Aurora generally makes its first appearance, or, which is 

 the same thing, the quarter in which the arch formed by this 

 meteor is usually seen. It is remarkable, that in this country 

 the Aurora has always been seen to the northward ; by the ex- 

 peditions which have wintered in the ice it was almost always 

 seen to the southward; and by the Blossom, in Kotzebue 

 Sound, 250 miles to the southward of the ice, it was, as in 

 England, always observed in a northern direction. Coupling 

 this with the relative positions of the margins of the packed ice, 

 and with the fact of the Aurora appearing more brilliantly to 

 vessels passing near the situation of that body, than by others 

 entered far within it, as would seem to be the case from the 

 reports of the Greenland ships, and from my observations at 

 Melville Island and at Kotzebue Sound, it does appear, at first 

 sight, that that region is most favourable to the production of 

 the meteor. I do not, however, presume to offer any hypo- 

 thesis on the subject ; but having witnessed the extraordinary 

 change that takes place in the atmosphere, along the whole 

 line of ice covering the Polar Sea, I should b^ remiss if 1 

 omitted to direct the attention of the natural philosopher to 

 the circumstance. There is perhaps no part of the globe 

 where the atmosphere vmdergoes a greater or more sudden 

 chanse than over this line of the ice. A diminution of 10 or 

 15 degrees of temperature constantly occurs within the space 

 of a few miles : the humid atmosphere over the ocean may 

 sometimes be seen laden with heavy clouds, which disperse as 



