VARIATION OF THE COMPASS. 63 



the magnetic meridian ; it is therefore probable that 

 the sun is the principal cause of both phenomena. 

 The circumstance of the situation of the magnetic 

 pole, in what appears to be (independent of elevation) 

 the coldest region of the globe, supported by the fact 

 of a diminished temperature causing an increase of 

 magnetic intensity, would lead us to infer that the 

 effect produced by the sun is principally to be attri- 

 buted to the heat developed by it. But should any 

 periodical effects, corresponding to the time of the 

 sun's rotation round its axis, be observable in the 

 diurnal variation, we must suppose that the sun like 

 the earth, is endued with magnetism, and look for a 

 cause of this magnetism common to all the planets. 



The Magnetic Equator. 



The magnetic equator crosses the terrestrial four 



times; viz. in 25 East, and in 108, 125, and 



170 West. The eastern and western lines of no 



' variation are traced in a chart in one of the early 



numbers of Dr. Brewster's Journal. 



The North-west Magnetic Pole. 



Among the Georgian Isles on the north coast of 

 America, a balanced needle became so weak and 

 sluggish as to be nearly annihilated ; that is to say, 



The magnetic action of the real north pole of the 

 earth became as nothing compared with the strong 

 and direct attraction of the north-west magnetic pole, 

 evidently situated within the earth, whether as a line, 

 area, or point, is uncertain. If the latter, it may be 

 supposed to reside about lat. 70 N., long. 90 W. 

 from Greenwich, in which locality the observations 

 of Capts. Ross, Parry, Franklin, and Lyon, all agree. 

 If Capt. Parry had been able to proceed from Cape 

 Hallowell to the west, he would have sailed across 

 the magnetic pole. 



