158 
L1EUT.-C0L0NEL SABINE ON TERRESTRIAL MAGNETISM. 
With this approximate inclination we compute & at E. by S. = + 45° 04' ; and with 
this correction, and the same observations as before, we have more precisely 
4/ = — 1 12° 38' ; l at W. = — 46° 1 3' ; and 6 = - 87° 53'. 
Substituting this value of 6 in the formula 
sin * = nr i tan 6 sin % + frl sin (S' + £)> 
we have the corrections and the corrected declination as follows : — 
E. by S. ^ S. 
N.N.W. i W. 
N.N.W. 
N.W. by N. 
W. 
W. by S. A S. 
S.W. A w. 
S.W. by W. 
S.W. A s. 
E.N.E. 
E. by S. 
E. by S. 
E.S.E. 
S.E. by E. 
Correction 
Correction 
Correction 
Correction 
Correction 
Correction 
Correction 
Correction 
Correction 
Correction 
Correction 
Correction 
Correction 
Correction 
— 46 
03 ; 
+ = _ 
64 
+ 19 
46; 
136 
+ 41 
38; 
150 
+ 23 
31 ; 
138 
+ 46 
13; 
+ =_ 
158 
+ 44 
03; 
+ =- 
156 
+ 33 
04; 
^' = “ 
156 
+ 3/ 
32; 
+ =- 
154 
+ 29 
45; 
+ =- 
142 
— 41 
38; 
+ =- 
67 
— 45 
19; 
66 
— 45 
19; 
67 
— 42 
18; 
73 
-37 
32; 
73 
23; 
4 = — 108 
26 
19; 
+ = — 116 
33 
04; 
4/= — 108 
26 
24; 
ip — — 114 
53 
51 ; 
= — 112 
38 
58; 
-+ = — 112 
55 
05; 
4- = - 123 
01 
06: 
^ = — 116 
34 
54; 
4 = — 113 
09 
01 ; 
4 = — 108 
39 
32; 
yjy = — 111 
51 
53; 
+ = — 113 
12 
45; 
+ = — 116 
03 
40; 
+ = — 111 
12 
Mean ... - 1 1 3 23 
On comparing the values of 4> thus obtained from the observations on the easterly 
points, with those on the westerly points, it is evident that the remaining differences 
in the individual results are not occasioned by faults in the corrections, but that they 
are actual differences in the observations of azimuth. In the extreme circumstances 
to which the Expedition had attained, when by reason of the great amount of dip, the 
terrestrial force acting on the compass needle, and directing it to one part of the 
horizon in preference to another, was reduced to +yth part of the whole amount of 
the terrestrial magnetic force in the same locality, the degree of accordance which 
was still preserved assuredly surpasses expectation*. The result at S.W. \ W. is the 
only one which presents an excessive discordance ; and after a careful examination 
of the whole of the observations which the general table contains, it must be regarded 
* The compass used in the Erebus was the first of the new naval compasses made under the direction of a 
Committee appointed by the Admiralty “ for the improvement of ships’ compasses.” The magnet was com- 
posed of several thin plates of clock-spring suitably arranged, giving very considerable magnetic force, with a 
suspension improved both in mode and materials. This compass appears to have answered remarkably well 
in the very trying circumstances in which it was employed. Captain Ross was himself the Chairman of 
the Committee, which gave its services gratuitously : the other members were Captain Beaufort, R.N., 
Mr. Christie, Major Jervis, Captain Edward Johnson, R.N., and Lieut. -Colonel Sabine. 
