i 



26-1 On the Aurora Borealh. 



small duration seen in Ireland, by Mr. Neve, on the ]6th of 

 November 1 707 ;" also " one of short duration seen near 

 London, a I'ttle before midnight, between the ninth and 

 tenth of August 1708." 



It is, I believe, the opinion of some people, that this phae- 

 nomenon did not appear in England until the 6th of 

 March 1716, when it was very reniaikable; a particular 

 account of which is given in the paper of Dr. Hallev above 

 mentioned. Since that period it has been frequently ob- 

 served, I understand, untd of late. 



It occurred to me some time ago, that having had a good 

 deal of lightning lately, and very little of the aurora bo- 

 realis, the disappearance of the one and appearance of 

 the other might have some connection ; and 1 find in the 

 Gentleman's Magazine for January 17Jl the saine idea. 

 Mention i>- there made of an aurora borealis which was 

 seen in Soulh Carohna in April 1750, and that there had 

 been but very little thunder and lightning for several 

 months; and an observation made, that had there been as 

 much as usual, they would not have been witnesses of the 

 .aurora borealis in that part of the world. 



This appearance is generally, and in mv opinion with 

 good reason, imagined to he occasioned bv the tlectric fluid 

 darling about in the atmosphere. Dr. tiallcv suspected it 

 was caused by magnetical effluvia; for he remarks that 

 this " subtile matter freely pervading the pores of the earth, 

 and entering into it near its southern pole, may pass out 

 again into the ether at the same distance from the 

 northern;" and that "this n)atter may, by the concourse of 

 several causes very rarely coincident, and to us as vet un- 

 known, be capable of producing a small degree of light, 

 perhaps from the greater density of the matter, or the 

 greater velocity of its motion, after the same maimer as the 

 effluvia of electric bodies by a strong and quick friction 

 emit light in the dark, to which sort of light this seems to 

 have a great affinity." 



Dalton in his Meteorological Essays, published some 

 years ago, if I mistake not, remarks that the beams of the 

 aurora lie in the same direction as the magnetic needle 

 points, and that when they form a canopy of light, the ver- 

 tex of it is at the magnetic pole of that place. I do not 

 know whether this notion is original or not, but it is well 

 worth the attention of philosophers. In the Gentleman's 

 Magazine for January 1750, is an account of a remarkable 

 aurora borealis seen in Northamptonshire, the coruscations 

 of which " met not in the zenith, but in a point about 



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