154 
LIEUT.-COLONEL SABINE ON TERRESTRIAL MAGNETISM. 
Ship’s head 
Disturbance towards the west. 
Ship’s head 
Disturbance towards the west. 
by compass. 
1840. 
1841. 
Mean. 
by compass. 
1840. 
1841. 
Mean. 
N. 
O / 
+ 1 10 
0 c. 
-0 26 
+ 6 22 
S. 
O / 
-0 49 
O / 
+ 0 43 
O / 
-0 03 
n. by w. 
+ 0 24 
-1 14 
-0 25 
s. by E. 
— 0 01 
-t-2 32 
-fl 15 
N.N.W. 
-0 40 
-2 01 
-1 20 
S.S.E. 
+ 0 38 
+ 3 06 
+ 1 52 
n.w. by n. 
— 1 54 
— 2 34 
-2 14 
s.e. by s. 
+ 1 12 
+ 3 51 
+ 2 32 
N.W. 
— 2 10 
— 2 55 
— 2 32 
S.E. 
+ 1 35 
+ 4 34 
+ 3 04 
N.w. by w. 
-2 58 
-3 13 
— 3 05 
s.e. by e. 
+ 2 35 
+ 5 01 
+ 3 48 
W.N.W. 
-3 18 
— 3 51 
-3 35 
E.S.E. 
+ 3 17 
+ 4 45 
+ 4 01 
w. by n. 
-3 39 
— 4 32 
— 4 06 
e. by s. 
+ 3 12 
+ 5 21 
+ 4 17 
w. 
— 4 15 
-4 59 
-4 37 
E. 
+ 3 38 
+ 5 07 
+ 4 22 
w. by s. 
-4 13 
— 4 56 
— 4 35 
e. by n. 
+ 3 54 
+ 4 46 
+ 4 20 
w.s.w. 
-4 27 
-4 41 
— 4 34 
E.N.E. 
+ 3 30 
+ 4 06 
+ 3 48 
s.w. by w. 
-4 39 
-4 19 
-4 29 
n.e. by e. 
+ 3 21 
+ 3 45 
+ 3 33 
s.w. 
-4 06 
-3 40 
-3 53 
N.E. 
+ 3 12 
+ 3 08 
+ 3 10 
s.w. by s. 
-3 36 
-2 50 
-3 13 
n.e. by n. 
+ 2 50 
+ 2 39 
+ 2 45 
s.s.w. 
-2 30 
-2 15 
— 2 22 
N.N.E. 
+ 2 26 
+ 1 30 
+ 1 58 
s. by w. 
-1 39 
-0 19 
-0 59 
N. by E. 
+ 2 19 
+ 0 38 
+ 1 28 
Employing the same formula as before, and forming equations from the observa- 
tions on the twenty eight points, being all the points excepting the north, south, east 
and west, we obtain 
10-1036 b = + 9-9673 
b - + -9865 ; 
and from the sum of the thirty equations, including those at east and west, we have 
+ 57-89 a = + 1-0439 + ‘537 b, 
a = 
1-0439 + -5297 
57-89 
= + -0272. 
On the passage from Hobarton to the Antarctic Circle, the Expedition stopped at 
Auckland Island for the purpose of observing on the term day of November 1840. 
The Erebus was not swung at this station, but with the value of 6 observed on shore 
— 73° 10', and the declination observed on board whilst at anchor, with the ship’s 
head on the east and west points, and on the E.N.E. and W.N.W. points, we may 
obtain a satisfactory value for a. On the supposition of the symmetrical distribution 
of the iron on either side of the longitudinal midship section, the deviation occasioned 
by it should be the same in amount, but with opposite signs, at east and west, and 
also at E.N.E. and W.N.W. ; the amount, however, being slightly different at east 
and west from that at E.N.E. and W.N.W. 
From the observations at east and west we have 
ip 1 = — 12° 52' at east, and 4-' = — 22° 55' at west ; 
4 / _ _ _ 170 53 >. 5) and 
d = + 5° 01'-5 ; whence a = + '0265. 
