OF THE MAGNETIC FORCE. 



39 



1 Let m equal any reading at an even hour in 1843 or 1844, mp and mf the same for the odd hours preceding 



and following, then mean for the even hour J (m + m P + m J) which was substituted for the above value at the 



2 



even hour in 1843 and 1844 before the general mean of the four years was taken. 

 6 



