Magnetism of the Earth. 151 



Gulf of Guinea, in the northern hemisphere ; and in the southern 

 hemisphere, at the Island of Ascension, and at Bahia on the coast of 

 Brazil. 



We may hope that the further tracing of the curves, which have 

 not been subject to M. Hansteen's observation in Siberia, will ere 

 long be accomplished in the Asiatic quarter, by the scientific indus- 

 try of British officers employed in India ; w^here a line through the 

 British dominions, from Ceylon on the south, to the Himalaya Moun- 

 tains on the north, would probably intersect Nos. 5, 6, 7, and 8, 

 nearly at right angles to their course. 



Mr. David Douglas, well known to you as the enterprising travel- 

 ler and successful naturalist in the countries adjacent to the Columbia 

 river and its tributaries, returns in September, to the north w^est coast 

 of America, on an undertaking which will occupy him there many 

 months. He will be well provided with instrum.ents, and is practised 

 in the modes of observation. He hopes to determine the magnetic 

 phenomena, from California in the south, to the farthest extent to- 

 wards the north, to which circumstances may enable him to prose- 

 cute his researches ; and from the ocean on the west, occasionally to 

 the Rocky Mountains on the east. He will probably ascertain the 

 situation on the western side of North America, of the curves 3 and 

 4, and will approach No. 2, when at his eastern limits. But it is 

 from travellers in the interior of the United States, and in the coun- 

 tries adjacent to the Slave Lake and Coppermine River, that we must 

 expect exact determinations of this interesting curve No. 2. Un- 

 questionably, however, the space included by the innermost curve, 

 is the field for observations of the very highest importance on the 

 subject of the magnetism of the globe ; and as it is traversed annu- 

 ally under the direction of tlie Hudson's Bay company, we may con- 

 fidently hope, from the ready disposition w^hich that company has 

 shewn in so many instances to promote scientific researches, that 

 much time will not elapse, before that really important journey will 

 be performed by some person, properly qualified by previous prac- 

 tise, to observe with the precision necessary on so particular occa- 

 sion. 



In regard to the great space in the northern hemisphere occupied 

 b}'- the Pacific Ocean, the numerous islands with which it is inter- 

 spersed, present points of observation of easier access than many 

 parts of the respective continents. A commencement has already 

 been made by Captain Liitke, commanding one of the Russian ships 



