Sect, il.j 



TEHRESTRIAL MAGKETISM. 



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of Captain Owen Stanley in Torres Btrait and thr- co-ns 



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Behring's Strait; 



and of Captain 



To tliese must be added a very 



gst the 



in the Pacific and 



Stokes in New Zeah 



valuable magnetic survey still in progress amonj 



islands of the Indian Archipelago by Captain Elliot of 



the Madras Engineers, at the expense of the East India 



Company. 



When it is borne in mind that several of the above- 

 named surveys include periods of three or four years, and 

 in some instances not only determ_inations at the several 

 ports and harbours which may have been visited, but also 





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of the three mas- 



netic elements at sea in passages from port to port, the 

 accumulation of materials, and their already extensive 

 distribution over the surface of the globe, may in some 

 degree be judged of. No part of the globe has yet how- 

 ever been considered so far completed, that its magnetic 



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curves Lave been finally drawn, or the tables of the ms 

 netic elements corresponding to gcograpliical positions 

 finally derived from them. The results of eacli individual 

 series are computed and published as soon after they 

 have been received in a complete state, as can be accom- 

 plished by the establishment at Woolwich, which is very 

 limited in comparison with the duties it endeavours to 



perform. 



gnet 



are also provisionally drawn ; but the final co-ordination 

 of the different series, and their combination with the 

 results of the magnetic surveys carrying on at the same 

 time by governments and individuals in various parts of 

 the remaining fourth of the globe which is occupied by 



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