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MAGNETIC OBSERVATIONS ON THE BOUNDARY LINE 



less liable to an uucertainty from that source. We know, however, that the changes 

 are small, and, for the limited period OA'er which the observations extend, they may be 

 considered as merged in the local errors, and the average date of 1852 as belonging to 

 the resulting lines on the map. 



The foUomng tables give a general resume of the observations, and the correspond- 

 ing values in the computed system ; also the residuals, the distribution of which is the 

 best evidence of the successful representation of the general facts involved. 



The geographical position of points in the lines of equal declination and dip — iso- 

 genic and isoclinal lines — are also given in tables from which they may be readily 

 projected in any map. 



Obsei'vations of Declinations. 



