114 
LIEUT.-COLONEL SABINE ON TERRESTRIAL MAGNETISM. 
those by the deflectors, with the equivalent weights deduced from the comparison, 
are collected in the following Table. 
Station. 
Date. 
Intensity 
deduced by 
weights. 
Angles of deflection 
by 
Equivalent 
weights. 
Def. S. 
Def. N. 
Def. S. 
Def. N. 
Hobarton 
Sydney 
New Zealand. . . . 
On ice 
Falkland Islands . 
April 1841 
July 1841 
Aug. and Oct. 1841 
January 1842 .... 
April and Aug. 1842 
1-82 
1-685 
1-594 
1-939 
1-322 
56 28-6 
59 10-2 
61 46-9 
54 03-1 
71 11-8 
53 02-6 
55 37-0 
57 59-0 
50 35 0 
67 10-3 
grs. 
739 
7-05 
6- 84 
7- 65 
6-10 
grs. 
7-08 
6-77 
6-58 
730 
5-93 
By projecting these angles and weights, and proceeding in the manner described 
in the Third Number of these Contributions*, the values of w' in the following Table 
were obtained for each deflector, corresponding to each angle of deflection v ' ; and 
employing these values of w', the intensities I' entered in the general table of ob- 
servations have been computed by the formula 
T , T82 sin 56 28-6 , , _ < , 
1= w cosec r—2‘053 w cosec v . 
Besides the observations with the spare needle R. F. 4, employed as a deflector, 
angles of deflection were occasionally observed with the magnets N and S, belonging 
to the apparatus of the Erebus, used conjointly ; their magnetism, however, was so 
much inferior to that of R. F. 4, that, even when both were used together, their joint 
effect was less than the half of either pole of R. F. 4 ; their results would consequently 
be much inferior in precision to those of R. F. 4, and 1 have not therefore employed 
them. 
Def. S. 
Def. N. 
v r . 
w\ 
v\ 
w'. 
v\ 
w'. 
v\ 
w\ 
v f . 
w'. 
v\ 
w\ 
S ° 
grs. 
o 
grs. 
grs. 
grs. 
grs. 
o 
grs. 
jj 52 
7-87 
59 
7-11 
66 
6 47 
49 
7-49 
56 
6-76 
63 
6-19 
53 
7-76 
60 
7 01 
67 
6-39 
50 
7-38 
57 
6 67 
64 
6-13 
54 
765 
61 
6-91 
68 
6-31 
51 
7 27 
58 
6-57 
65 
6-06 
55 
7-54 
62 
6-82 
69 
6-24 
52 
7T7 
59 
6-48 
66 
6-00 
56 
7-43 
63 
6-73 
70 
6-17 
53 
7'07 
60 
6-40 
67 
5-94 
57 
7-32 
64 
6 64 
71 
6-10 
54 
6 97 
61 
6-33 
58 
7-21 
65 
6-55 
72 
6 03 
55 
6-86 
62 
6 26 
In the Terror, the spare needle marked C was employed both as “ deflector N” and 
“ deflector 8.” The magnets belonging to the apparatus were also used, N separately, 
and N and S conjointly. Observations were also occasionally made with magnet 8, 
but its magnetism was so feeble, and the deflections obtained with it consequently so 
small in comparison with the others, that the results are not entitled to the same 
confidence, and have not therefore been taken into the account. The equivalent 
weights have been obtained, as in the Erebus, from the comparative observations 
with weights and deflectors at Hobarton, 8ydney, New Zealand, the Falkland 
* Philosophical Transactions, 1842, Art. II. 
