66 MAGNETIC INTENSITY, FERN ROCK OBSERVATORY. 



m 



TABLE OF RESULTS OF log. , log. m X, OF m THE MAGNETIC MOMENT OF MAGNET A. 67, AND OF THE 

 HORIZONTAL INTENSITY X, AT VAN RENSSELAER HARBOK. 



RECAPITULATION OF VALUES OF X. 



January 31,1854 A'= 1.117 



February 20, " 1.117 



Juno 15, " 1.121 



May 18, 1855 1.203 



Mean corresponding to June, 1854 . . . 1.139 



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

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

 Harbor during the same period becomes <p= 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 



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

 bat a small loss of magnetism during nearly four years. 



