158 On Noises accompanying the Aurora BoreaUs. 



our positive knowledge. Unfortunately, we live, since the be- 

 ginning of this century, in one of the great pauses of this phe- 

 nomenon ; so that the present generation knows but little of it 

 from personal observation. It would, therefore, be very agree- 

 able to receive, from older people, observations of this kind, 

 made in their youth, when the aurora borealis shewed itself in 

 its full splendour. It can be proved mathematically, that the 

 rays of the northern lights ascend from the surface of the earth, 

 in a direction inclining towards the" south {an inclination which, 

 with us, forms an angle of about 73°.) If, then, this light oc- 

 cupies the whole northern sky, rising more than 17° above the 

 zenith, the rays must proceed from under the feet of the ob- 

 server, although they do not receive their reflecting power till 

 they have reached a considerable elevation, . perhaps beyond our 

 atmosphere. It is therefore conceivable, why we should fre- 

 quently hear a noise attending the northern lights, when the in- 

 hahitants of southern coimtiies, who see these phenomena at a 

 distance of many hundred miles, hear no report whatever. 

 Wargentin, in the fifteenth volume of the Transactions of the 

 Swedish Academy^ says, that Dr Gisler and Mr Hellant, who 

 had resided for some time in the north of Sweden, made, at the 

 request of the Academy, a i*eport of their observations on the 

 aurora borealis^ 



The following extract is given by Hansteen from Dr Gisler's 

 account : — " The most remarkable circumstance attending the 

 northern lights is, that, although they seem to be very high in 

 the air, perhaps higher than our common clouds, there are yet 

 convincing proofs that they are connected with the atmosphere, 

 and often descend so low in it, that, at times, they seem to touch 

 the earth itself; and, on the highest mountains^ they produce an 

 effect like a wind round the face of the traveller ^ He also says, 

 that he himself, as well as other credible persons, " had often 

 heard the rushing of them, just as if a strong wind had been 

 blowing (although there was a perfect calm all the time), or like 

 the whizzing heard in the decomposition of certain bodies during 

 a chemical process." It also seemed to him_, that he noticed ' a 

 smell of smoke or burnt salt.'''' — " I must yet add," says Gisler, 

 " that people who had travelled in Norway, informed me they 

 have sometimes been overtaken, on the top of mountains, by a 

 1 



