66 MAGNETIC INTENSITY, FERN ROCK OBSERVATORY. 



Table of Results of log. — , log. m X, of m the Magnetic Moment of Magnet A. 67, and of the 

 X. 



Recapitulation of Values of X. 



January 31, 1854 

 February 20, " 

 June 15, " 

 May 18, 1855 



= 1.117 

 1.117 

 1.121 

 1.203 



1.139 



Mean corresponding to June, 1854 



Taking the above value 1.139 for the mean horizontal force during the whole 

 period, and multiplying it by sec. 84° 45'. 8, tlie total force at Van Rensselaer 

 Harbor during the same period becomes ^=12.479. 



By means of the known value of m the horizontal intensity at the stations 

 Hakluyt Island and coast near Cape York has been computed as follows: — 

 Hakluyt Island, June 21, 1855 . . X= 1.344 

 Coast near Cape York, July 19, 1855 . X 1.573 



' I redetermined m at Washington, D. C, in March, 1858, and found it equal to 0.311, exhibiting 

 but a small loss of magnetism dnring nearly four years. 



