198 On the supposed infltience of the 



In one column is the amount of the daily variation, and in ano- 

 ther column are placed all the Auroras which were visible, so 

 that we can compare the mean oscillation of the needles during 

 a period when there were no Aurorse, with the mean oscilla- 

 tion during a period when there were many Aurorae, and thus 

 obtain the united effects of groups of these motions. 

 The following table will put this in a clear light. 



Mean. 



3 18 41' 



These comparisons, which Lieutenant Foster seems to have 

 overlooked, present a very curious result. In place ofexer^ 

 cising a disturbing infltiejice, the Aurorce in the Arctic Regions 

 would seem to exercise a sedative influence upon the needle. 



The observations from which this conclusion is deduced 

 were made by seven difterent observers, Captain Parry, Lieut. 

 Foster, Lieut. Sherer, Lieut. Ross, and Messrs Crozier, Rich- 

 ards and Head. " The needles were visited every hour during 

 four successive months;" and as Lieut. Foster observes, " when 

 any extraordinary change appeared to be going on, the needles 

 were more closely watched ; and every phenomenon, such as 

 the Aurora Borealis, meteors, clouds, the kind and degree of 

 light, the moon's position, and the temperature within and 

 without, were at all times carefully noted ;" * and he con- 

 tinues, " we have reason to believe, that on no occasion were tlie 

 needles in the slightest degree affected hy the Aurores, meteors, 

 or any other perceptible atmospheric phenomenon." •(- 



» Phil. Trans, 1826, Part iv. pp. 75, 76. 



+ In speaking of a motion of the needle on the 27th March, Lieutenant 

 Foster states, that there was no appearance of an Aurora ; and he adds in 

 a note, " The Aurora generally appeared about N. by compass, extending 

 in an arch from about N. E. to N. W., at an elevation from 10° to 20°, 



