192 On the supposed injluence of' the 



city of the heated air, and who attributes the disturbance of the 

 needle, not to the Aurora, but to the effect of the same heat on 

 the great terrestrial magnet, — a result which he has illustrated, 

 by placing a needle under the influence of heated magnets. Mr 

 Canton regards this opinion as strengthened by the fact, that 

 the inhabitants of northern countries observe the Aurora to be 

 remarkably strong when a sudden thaw happens after severe 

 cold weather. This opinion is countenanced by the observa- 

 tion of Mr Winn, recorded in the Phil. Trails, for 1774. 



" I believe the observation is new that the Aurora Borealis is 

 coiutantly succeeded by hard southerly or south-west winds, 

 (the warmest winds in this climate,) attended with hazy weather 

 and small rain. I think I am warranted from experience to 

 say constantly ; for in twenty-three instances that have occur- 

 red since I first made the observation, it has invariably obtain- 

 ed. The gale generally commences between twenty-four and 

 thirty hours after the first appearance of the Aurora."" 



The Reverend James Farquharson of Alford, in Aberdeen- 

 shire, who has observed the Aurora for many years, states the 

 same opinion, that it precedes or accompanies westerly or 

 south-easterly * gales. These views will receive a singular 

 confirmation when we examine the observations of Colonel 

 Beaufoy ; and we have adduced them, not as our own opinion, 

 but in order to show that very competent judges have believed, 

 that the Aurora Borealis is the effect of a cause which may also 

 produce agitations in the magnetic needle, and that the two 

 phenomena may co-exist, either occasionally or constantly, with- 

 out the one being the cause of the other. 



We now come to a period when the variation of the magne- 

 tic needle became the subject of regular observation. Colonel 

 Beaufoy, a name which will ever be venerated in the annals of 

 English science, began at Hackney, near London, a regular 

 series of observations, not only on the magnetical needle, but 

 on the state of the atmosphere. He observed, with a delicate 

 apparatus, the variation of the needle three times a-day. His 



• We suspect this to be a typographical error for south-westerly, as the 

 author in the very next paragraph describes a fine Aurora during a souths 

 westerly gak. 



