\ 
148 _ Polar Explorations. 
and even 7°; ;” and it is their opinion that the changes in 
amount are due to the influence of the sun, and probably of 
the moon, on the terrestria] magnetic sphere. The particu- 
lar law of this influence remains unascertained. It is a ques- 
tion whether the diminishing intensity of a mesnetized nee- 
dle in constant use, may not have caused some disturbance 
but if that were the case, the variations hac have di aie 
ished in a constant and regular ratio. They therefore im- 
agine a small revolution of the polar point around its own 
center, produced by the action of the sun. This theory ap- 
pears to accord with observations in peculiar and various 
situations in remote parts of the globe. In no instance w 
the magnetic influence affected by the Aurora Borealis he 
ing the three winters of Capt. Parry’s residence within the 
polar circle. The observations upon the needle were made 
in a snow house, at a distance from the ships, in order to 
avoid the effect of their attraction. | 
C. ranklin remarks that when the Aurora was stream- 
ing with prismatic colors, it had an obvious effect upon the. 
magnetic needle, but that when it was of a steady dense 
light without motion, the needle remai unmoved. H 
infers that the feebleness of the electric fluid in the higher 
latitudes, where it was seen by Capt. Parry, is the cause of 
selfand Capt. Parry. If the cause of the variation of the 
needle can be ascertained, and the laws which regulate it 
* Edin. New Phil. Jour. March, 1827. 
