282 STAFF COMMANDER EYANS AND MR. A. SMITH ON THE MAGNETIC 
Lisbon upright, and heeled about 7° to starboard and to port. The agreement of the 
values of the coefficient ~ derived by the different methods is not very satisfactory, and 
it can only be considered as a rough approximation to the truth. 
From the equation for comparison of semicircular deviation in different latitudes 
?+Htan^=9BH. 
P c_ 
A* A 
Warrior .... — ‘471 +‘058 
Black Prince . . . +‘061 +-142 
Defence .... +‘206 +‘079 
Resistance. . . . —330 + T90 
From heeling-error formulae. jj. 
A 
Warrior +T08 
Black Prince +*181 
Defence +T19 
Taking the mean of the several values in the ships. 
Original 
value of B. 
c 
a 
Part of B 
from soft iron. 
Part of B 
from hard iron. 
Warrior 
-241 
•083 
+ 12 
— 3&1 
Black Prince 
+ 23 
•161 
+ 23 
0 
Defence 
+ 25f 
•099 
+ 141 
+ 114 
Taking the present values of B 
in the ships. 
B. 
C 
Part of B 
Part of B 
k 
from soft iron. 
from hard iron. 
Warrior 
-17 
•083 
+ 12 
-29 
Black Prince 
+ 19 
•161 
+ 23 
— 4 
Defence 
+ 21 
•099 
+ 141 
+ 61 
And in any other magnetic latitude for which the horizontal force is H, the hori- 
zontal force in England being 1 and the dip 6 , we should have 
O 
29 ° 
Warrior .... B=— jj +4f tan 6 . 
Black Prince. . . B= — g + 9^ tan 0. 
o 
Defence .... B= ^|+5§tan0. 
also to William Mates, Esq., Master of Her Majesty’s Ship Defence, for a valuable series of observations made 
in that ship, and for his exertions in obtaining results in several ships of the Channel Squadron. 
