THE EARTH A MAGNET. 2$ 



the south, in like manner, there are also two poles, 

 one on the Antarctic circle, about 130 E. long., in 

 Adelie Land, the other not yet precisely determined, 

 but supposed to lie on about the 240th degree of 

 longitude, and south of the Antarctic circle. Singularly 

 enough, there is a line of lower intensity running right 

 round the earth along the valleys of the two great 

 oceans, passing through Behring's Straits and bisecting 

 the Pacific, on one side of the globe, and passing out of 

 the Arctic Sea by Spitzbergen and down the Atlantic, 

 on the other.' 



Colonel Sabine discovered that the intensity of the 

 magnetic action varies during the course of the year. 

 It is greatest in December and January in both hemi- 

 spheres. If the intensity had been greatest in winter; 

 one would have been disposed to have assigned seasonal 

 variation of temperature as the cause of the change. 

 But as the epoch is the same for both hemispheres, we 

 must seek another cause. Is there any astronomical 

 element which seems to correspond with the law dis- 

 covered by Sabine? There is one very important 

 element. The position of the perihelion of the earth's 

 orbit is such that the earth is nearest to the sun on 

 about the 31st of December or the 1st of January. 

 There seems nothing rashly speculative, then, in con- 

 cluding that the sun exercises a magnetic influence on 

 the earth, varying according to the distance of the earth 

 from the sun. Nay, Sabine's results seem to point very 

 distinctly to the law of variation. For, although the 

 number of observations is not as yet very great and 



