LIEUT.- COLONEL SABINE ON TERRESTRIAL MAGNETISM. 
89 
of her voyage in which she might be sailing from lower into higher inclinations, 
and to another portion in which she might be returning from higher into lower 
magnetic latitudes. The voyage under consideration comprised two such portions ; 
and I have therefore employed two tables for the Erebus, one computed with ’0267 
for the period when the ship was increasing the dip, and the other with -0288 for the 
period when she was decreasing the dip. The differences are insignificant, except 
when the inclination is very high ; the greater part of the declinations observed in 
the high dips were antecedent to the 1st of March 1842, when the ship commenced 
her return to the lower latitudes ; for these the table computed with a = ' 0267 
has been employed, and appears to answer better than the corrections computed 
either by the values resulting from the observations at Hobarton before the com- 
mencement, or by those at the Falkland Islands after the conclusion of the voyage. 
2. In the Terror . — For the values of a and h in the Terror, we have observations 
on each of the thirty-two principal points of the compass at Hobarton in October 1840, 
and a second series in June 1841, as follows: — 
Ship’s head by 
Disturbance towards the west. 
Ship’s head by 
Disturbance towards the west. 
compass. 
1840. 
1841. 
Mean. 
compass. 
1840. 
1841. 
Mean. 
N. 
+ 0 42-4 
— 0 52 
— 0 05 
s. 
o / _ 
-0 11-6 
o / 
— 0 55 
o / 
— 0 33 
n. by w. 
-0 23-6 
— 0 52 
— 0 38 
s. by e. 
+ 0 52-4 
-0 06 
+ 0 23 
N.N.W. 
— 1 20-6 
-0 59 
— 1 10 
S.S.E. 
+ 1 56-4 
+ 0 43 
+ 1 20 
n.w. by n. 
-2 20-6 
— 0 03 
— 1 12 
s.e. by s. 
+ 2 38-4 
+ 2 08 
+ 2 23 
N.W. 
-3 25-6 
-0 58 
— 2 12 
S.E. 
+ 3 19-4 
+ 2 57 
+ 3 08 
n.w. by w. 
—3 56-6 
— 2 12 
-3 04 
s.e. by e. 
4-4 00-4 
+ 3 48 
+ 3 54 
W.N.W. 
-4 01-6 
— 2 26 
— 3 14 
E.S.E. 
+ 4 43-4 
+ 5 25 
+ 4 54 
w. by n. 
-4 06-6 
— 2 51 
-3 29 
e. by s. 
+ 4 28-4 
+ 4 58 
+ 4 43 
w. 
-4 36-6 
-3 34 
— 4 06 
E. 
+ 4 24-4 
+ 4 27 
+ 4 26 
w. by s. 
— 4 44-6 
-3 43 
-4 14 
e. by n. 
+ 4 11-4 
+ 4 02 
+ 4 07 
w.s.w. 
-4 52-6 
— 4 34 
— 4 43 
E.N.E. 
+ 4 07-4 
+ 3 27 
+ 3 47 
s.w. by w. 
-5 22-6 
-4 01 
-4 42 
n.e. by e. 
+ 3 27-4 
+ 3 04 
+ 3 16 
s.w. 
— 4 23-6 
-3 50 
-4 07 
N.E. 
+ 3 02-4 
+ 3 01 
+ 3 02 
s.w. by s. 
-3 31-6 
— 4 22 
-3 57 
n.e. by n. 
+ 2 37-4 
+ 2 27 
+ 2 32 
s.s.w. 
— 2 03-6 
— 3 41 
— 2 52 
N.N.E. 
+ 2 11-4 
+ 0 46 
+ 1 29 
s. by w. 
-1 37-6 
— 2 44 
— 1 11 
n. by e. 
+ 1 26-4 
-0 12 
+ 0 37 
We have also a series at Port Louis, in the Falkland Islands, in August 1842, as 
follows : — 
Ship’s head by 
compass. 
Disturbance 
towards the 
west. 
Ship’s head by 
compass. 
Disturbance 
towards the 
west. 
o / 
O / 
N. 
+ 0 19 
w. 
-2 30 
N. by w. 
-0 02 
w. by s. 
— 2 21 
N.N.W. 
— 0 17 
w.s.w. 
— 2 12 
n.w. by n. 
-0 48 
s.w. by w. 
-2 21 
N.W. 
-1 19 
S.W. 
— 1 33 
N.w. by w. 
-1 49 
s.w. by s. 
— 1 05 
W.N.W. 
— 1 47 
s.s.w. 
-0 47 
w. by n. 
-2 07 
s. by w. 
— 0 45 
Ship’s head by 
compass. 
Disturbance 
towards the 
west. 
Ship’s head by 
compass. 
Disturbance 
towards the 
west. 
s. 
° L 
-0 16 
E. 
° A. 
+ 2 46 
s. by e. 
— 0 08 
e. by n. 
+ 2 27 
S.S.E. 
0 00 
E.N.E. 
+ 1 58 
s.e. by e. 
+ 0 47 
n.e. by E. 
+ 1 39 
S.E. 
+ 1 35 
N.E. 
+ 1 13 
s.e. by e. 
+ 2 17 
N.E. by N. 
+ 1 11 
E.S.E. 
+ 3 04 
N.N.E. 
+ 0 34 
e. by s. 
+ 2 33 
N. by e. 
+ 0 27 
N 2 
