TERRESTRIAL MAGNETISM 315 



lines) and the lines of equal dip for 1876. It will be seen that 

 there are two poles or points of 90 clip. That in the Northern 

 Hemisphere in the neighbourhood of lat. 70 5' N. and long. 



FIG. 236. 



96 46' W. was reached in 1831 by Captain James Ross. In 1903 

 the region was again visited by Amundsen, who made a stay of 

 two years, carrying out an extensive magnetic survey there. The 



Vest Variation 



FIG. 237. 



South magnetic pole was reached in 1909. It is about 72 S. lat. 

 and 155 E. long. 



Fig. 237 shows lines of equal declination or isogonic lines, and 



