

TERRESTRIAL MAGNETISM. 



[Sect. II. 



laud, is deferred until the accumulation of materials in 

 the more frequ^uted portions shall appear sufficient for 

 the purpose, and until in the less frequented portions 

 there shall be no immediate prospect of any further con- 

 siderable accession. The final period at which the work 

 may be completed cannot but be accelerated by the step 

 which the Lords Com.missioners of the Admiralty have 



taken, in desiring the |)resent notice to be drawn up, and 



in holding out inducement-- to naval officers of professional 



and other advantages, as a recompense for what may in 

 some respects be regarded as extra -professional services. 

 With due hesitation in expressing an opinion on what is 

 future, and contingent on many circumxstances, it may be 

 stated that hopes are entertained that the year 1851 may 

 see the v/ork completed. 



In prosecuting a work of this general and purely expe-^ 

 rimental character, unconnected with hypothesis of any 

 sort, the phenomena of all parts of the globe must be 

 viev/ed in the abstract as possessing an equal importance ; 

 and it does not appear desirable, therefore, to name any 

 one of the lines, whether isogonic, isoclinal, or isodynamic, 

 as deserving of special attention in preference to others. 

 There is one direction, however, which may be safely 

 iven, and which it may be well to remember at all times, 

 viz.j that " the value of each new station is directly pro- 

 portional to its distance from those where observations 

 have already been made ;" and in this point of view it 

 may be useful to notice, that up to the present time fewer 

 observations have been made in the Pacific than either in 

 the Atlantic or the Indian Oceans. 



APP 



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