Prof. Hansteen on the Polar Lights. 335 



my thermometers are suspended, and from which I observe 

 the appearance of the sky, lying towards N.E. and S.W. 

 The 21st of April the sky was overcast. At Stordalen, near 

 Drontheim, where meteorological observations are made by 

 Mr. Heyerdahl, the rector, the 30th and 3 1 st of March were 

 snowy, and the 1st of April, a cloudy sky; the 17th of August, 

 at 10 P.M. we had rain at Christiania ; at Vadso, near War- 

 dochusw, at 9 P.M., by Mr. Stockfleth, the rector,'s observa- 

 tion, the atmosphere was dull; the 21st at half-past IJ, 

 cloudy ; the 25th, at 1 1 o'clock 40 minutes, at Christiania, 

 clear, with aurora borealis, which was also observed by Mr. 

 Prebend Herzberg, at Hardanger ; the 29th at midnight, clear, 

 a little cloudy near the horizon. But in the meteorological 

 tables of July, August, and September, communicated during 

 my absence by Mr. Holmboe, the lecturer, on a journey round 

 the gulf of Bothnia, the observation occurs: "In the latter 

 days of August, aurorae were seen on several evenings," which, 

 according to what I have been told by Mr. Holmboe, had 

 been unobserved by himself, but seen by others. The 1 0th, 

 Mr. H. saw, at Christiania, a beautiful arch of aurora below 

 Ursa Major, and therefore the same which had been seen a 

 little before at Leith. The 7th of October in the evening, the 

 sky was overcast at Christiania; the 3rd and 4th of November, 

 it snowed there in the evening : at Bergen, however, an 

 aurora was seen by Mr. Bohr. The 22nd, the sky at Chris- 

 tiania was clear, but no aurora is noticed. 



Ml". Holmboe's observation relative to the many aurorae 

 boreales seen in the latter part of August, makes it very pro- 

 bable that they appeared during the 21st, 22nd, and 23rd, of 

 that month ; which were the days when the irregularities of 

 the needle were observed in Paris, without any auxora? having 

 been noticed in Edmburgh : and we should consequently not 

 be obliged to assume with M. Arago, "that there are other 

 unknown causes which act on the motions of the magnetic 

 needle." 



The following observations, with respect to the above re- 

 marks of M. Arago on the spontaneous action of the aurora 

 on the magnetic needle in very distant places, are rather in- 

 teresting. From the 23rd till the 31st of August, I resided 

 at Haparanda, near Torneo. In order to discover whether 

 the usual variation in magnetic intensity which I found in 

 Christiania, was also observable near the arctic circle, I ob- 

 served from a wimlow of the inn, the time of 300 horizontal 

 oscillations with one of DoUond's cyluiders, as follows. 



Day. 



