TERRESTRIAL MAGNETISM. 11 J 



in 174 W. long., but in the meridian of the Viti group, 

 in about 177^ E. or 182i W. long., Therefore, in 

 proceeding to the west from the coast of Africa, we find the 

 distance between the two nodes Si greater than the earth's 

 semi-circumference, a proof that the curve in question is 

 not a great circle. 



According to the excellent and widely-extended determi- 

 nations of Captain Elliot (18461849), which between the 

 meridians of Batavia and Ceylon are remarkably accordant 

 with those of Jules de Blosseville (see p. 67 of the present 

 volume), the line of no inclination passes across the north 

 of Borneo, and running in an almost exactly east and west 

 direction, touches the north point of Ceylon (9 45' N. lat.) 

 The curve of least total force is in this part of the world 

 almost parallel with that of the magnetic equator. ( 132 ) The 

 latter enters the east coast of Africa south of Cape Gardafui : 

 this important point has been determined with great exact- 

 ness by Rochet d'Hericourt in his second Abyssinian expe- 

 dition (1842 1845), and by the able discussion of that 

 traveller's magnetic observations^ 133 ) It is situated south 

 of Gaubade, between Angolola and Angobar (the principal 

 town of the kingdom of Shoa), in 10 7' N. lat. and 

 41 13' E. long. The course of the magnetic equator 

 through the interior of Africa, from Angobar to the Bight 

 of Biafra, is as entirely unexamined as is the portion of the 

 same line which passes through that part of the interior of 

 South America which is east of the chain of the Andes and 

 south of the geographical equator. These two continental 

 spaces are of about equal extent in an east and west direc- 

 tion, and taken together occupy 80 degrees of longitude, or 

 nearly a quarter of the earth's circumference, in which there 



