148 TERRESTRIAL MAGNETISM. 



again a little to the east of Para, near Cape Tigioca, at 

 one of the mouths of the Amazon (Rio de Para), it cuts 

 the geographic equator in 48 30' W. long., and runs at 

 a distance of nearly ninety miles from the coast of 

 GKiyana up to 5 of North latitude, from whence, follow- 

 ing the curve of the smaller West-Indian Islands, it 

 ascends to 18 N. lat., and passes from thence to the coast 

 of North Carolina, which it enters in lat. 34 50' 9 W. long. 

 76*30 / , near Cape Lookout, south-west of Cape Hatteras. 

 In the interior of North America this curve continues its 

 north-west direction to lat. 41-1- , long. 80, towards 

 Pittsburgh, Meadville, and Lake Erie. There is reason 

 to suppose that it may already have moved, in some 

 parts of its course, more than a degree to the west since 

 1840. 



The Australo- Asiatic curve of no declination, if, with 

 Erman, we regard the line which at Kasan trends north- 

 wards to Archangel and Eussian Lapland, as part of the 

 same line which passes the Moluccas and the Sea of 

 Japan, can scarcely be traced in the southern hemi- 

 sphere so far as the 62d degree of latitude. Its most 

 southern known point is more to the west of Van 

 Diemen Island than was previously supposed. The 

 three points at which Sir James Ross, ( 19 ) in his ant- 

 arctic voyages of discovery, crossed it in 1840 and 1841, 

 in the parallels of 62, 54^-, and 46, were all between 

 the longitudes of 133-20' and 135 -4(X East, showing an 

 almost north and south direction in this part of its 

 course. It then traverses Western Australia, entering 

 the south coast of Nuyts Land (about ten degrees west 

 of Adelaide), and quitting the northern coast near 

 Vansittart River and Mount Cockburn. From hence it 



