MAGNETIC SURVEY OF JAPAN FOR THE EPOCH 1895.0. 123 



/30 /S2 /su. 



/SS /SS /'/o /^^ /•^^ 



The above method is unsatisfectory, and the small value of 

 the mean enrrent density is sometimes misleading ; for in the 

 first place it gives no information of current densities in dif- 

 ferent parts of the country where they might have any values 

 with opposite signs ; and in the second place the integration is 

 carried out along tlie borders where the empirical formulae be- 

 come very poor representatives of isomagnetics owing to the 

 increase of errors as shown in p. 35 above. 



Transformino- the line integral into surface integral in the 

 usual wav, we 2;et the details of its distribution thus, 



