TERRESTEIAL MAGNETISM. 151 



nearly two thirds of the breadth of Northern Asia in this 

 its widest part (a space now entirely occupied by east 

 declination), that we arrive at a line of no declination, 

 which, at the north-eastern part of Lake Baikal, west of 

 Viluisk, ascends towards a point situated in the meridian 

 of lakutsk, or in about 130 E. long., and as much as 

 68 N. lat., from whence it redescends towards Ochotsk 

 (in 143 10' E. long.), forming the outermost line of the 

 eastern side of the oval-shaped group of concentric 

 declination-lines which has been before alluded to, and 

 then crosses the Kurile Islands, passing south into the 

 Sea of Japan. The isogonic lines from 5 to 15 east 

 declination, which occupy the space between the east 

 and west Asiatic lines of no declination, are all concave 

 towards the north. Their greatest curvature falls, 

 according to Erman, in long. 80, or in a meridian 

 nearly intermediate between Omsk and Tomsk, and not 

 very different from that of the southern point of the 

 peninsula of Hindostan. The longer axis of the closed 

 oval group extends through twenty-eight degrees of 

 latitude, or about to the Corea. 



A similarly shaped group or system of declination- 

 lines, but of larger dimensions, presents itself to our 

 observation in the Pacific. The closed curves there 

 form an oval extending from 20 N. to 42 S. latitude. 

 The principal axis is situated in 130 W. long. The 

 most remarkable feature of distinction between this 

 singular group (the greater portion of which is in the 

 southern hemisphere, and which is wholly oceanic), and 

 the previously described continental group of Eastern 

 Asia, is that in the Pacific group it is East declination 

 which decreases, while in the Asiatic oval it is West 



