104 
LIEUT.-COLONEL SABINE ON TERRESTRIAL MAGNETISM. 
From these observations we have the true inclination at these six stations as follows : — 
On ice, lat. — 65 49. Long. 202 02 . . 79 39-5 
On ice, lat.- 63 23. Long. 210 02 .. 77 23-3 
Hobarton 70 40'7 
Sydney 62 49‘ 1 
New Zealand 59 31*9 
Falkland Islands 52 26 2 
The observations with R. F. 5, at the same stations, and at the same spots on shore, 
or on the ice, gave as follows : — 
On Ice. 
Lat. -65° 49'. 
Long. 202° 02'. 
On Ice. 
Lat. -63° 2y. 
Long. 210° 02'. 
Hobarton. 
Sydney. 
New Zealand. 
Falkland Islands 
Face East —79 35 - 6 ■ 
-77 15*5 
— 7°0 26-4 
— 62 46-3 
— 59 29-8 
— 52 32-9 
Face West —80 39’2 
-78 20-3 
— 71 20-3 
— 63 44 3 
— 60 27*9 
— 53 34*7 
Mean —80 07’4 
-77 47*9 
— 70 53-4 
-63 15-3 
— 59 58'8 
— 53 03-8 
We have thus the following index corrections 
: — 
Face East — 3-8 
- 7-8 
- 14*3 
- 2-8 
1 
— 2-1 
+ 6-7 
Face West +59*7 
+ 57*0 
+39-6 
+ 55-2 
+ 56-0 
+68-5 
Mean correction +27*9 
+ 24-6 
+ 12-7 
+ 26-2 
+ 26-9 
+37*6 
and the difference of the results with the face east and face west as follows : — 
63-6 64-8 53-9 58’0 58* 1 61 *8 
From the signs and numerical values of the corrections of the mean results with 
R. F. 5, we may infer that the axis of rotation in this needle deviated from the centre 
of gravity in the longitudinal direction, so as to cause the south end of the needle 
slightly to preponderate. From the differences of the results with the face east and 
face west, it appears that there was also a small deviation in the axis of rotation 
from the centre of gravity in the perpendicular direction. In the results with the 
face east, these two sources of error partially counteracted each other, so that the 
index correction with the face east amounted at no time to more than a very few 
minutes. 
The corrections which have been applied to the observations have been taken from 
the following table, in which the correction for —70° has been taken as — 5'*8, and 
the change in the correction, corresponding to an increase of one degree in the 
south dip, as — 0'5. In forming this table the determinations on land have been 
allowed a greater weight than the determinations upon the ice, the latter consisting 
of fewer observations, and being made probably under circumstances less favourable 
for this particular purpose. 
