390 
MR. CHRISTIE ON THE MAGNETICAL OBSERVATIONS 
Places from the observations 
Observed 
Magnetic 
Error, or 
Value of 
Value of 
Error, or value of 
at which the position of the pole 
variation 
polar 
Dip. 
tan S . tan < p. 
value of 
d . 8 
3 cos 2 £+5 
d . 8 3 cos 2 8+5. 
of convergence is determined*. 
of the 
distance. 
tan S .tan <p— 2. 
4 
d.\ 4 
needle. 
o 
/ 
o 
/ 
// 
o 
/ // 
2-7519 
Fort Alexander 1 
15 
16 E.f 
28 
22 
43 
78 
53 37 
+ 0-7519 
•2874 
•5527 
- -2653 
and Cumberland House J 
19 
14 E.f 
26 
16 
11 
79 
29 59 
2-6630 
+ 0-6630 
Cumberland House 
19 
14 E. f 
22 
20 
28 
79 
29 59 
2-2173 
+ 0-2173 
-•1316 
•5499 
- -4183 
and Isle a la Crosse 
23 
19 E.f 
22 
8 
26 
79 
28 24 
2-1897 
+ 0-1897 
Isle a la Crosse 
.... 
23 
19 E.f 
32 
13 
34 
79 
28 24 
3-3931 
+ 1-3931 
•6921 
•5431 
+ -1490 
and Fort Chipewyan 
... 
25 
30 E.f 
30 
0 
16 
81 
0 39 
3-6504 
+ 1-6504 
Fort Chipewyan 
[ ... 
25 
30 E.f 
21 
19 
2 
81 
0 39 
2-4668 
+ 0-4668 
•6244 
•5325 
+ -0919 
and Fort Resolution 
r 
29 
15 E.f 
19 
38 
56 
82 
3 9 
2-5575 
+ 0-5575 
Fort Chipewyan 
25 
30 E.f 
10 
6 
50 
81 
0 39 
1-1276 
- 0-8724 
■7044 
•5325 
+ -1719 
and Fort Resolution 
... 
37 
20 E. 
8 
38 
6 
82 
3 9 
1-0878 
- 0-9122 
Fort Resolution 
1 ... 
37 
20 E. 
9 
4 
53 
82 
3 9 
1-1449 
- 0-8551 
•7521 
•5220 
+ -2301 
and Fort Reliance 
... 
35 
19 E. 
6 
28 
11 
84 
1 0 
1-0770 
- 0-9230 
Fort Reliance 
L » 
35 
19 E. 
7 
13 
11 
84 
1 0 
1-2087 
- 0-7913 
•9148 
•5116 
+ -4032 
and Musk-Ox Rapid 
.. 
44 
24 E. 
5 
30 
14 
85 
53 32 
1-3417 
_ 0-6583 
Musk-Ox Rapid 
44 
24 E. 
7 
52 
46 
85 
53 32 
1-9271 
- 0-0729 
•5205 
•5047 
+ -0158 
and Rock Rapid 
... 
29 
16 E. 
4 
29 
4 
87 
39 34 
1-9188 
- 0-0812 
Rock Rapid 
I ... 
29 
16 E. 
2 
21 
16 
87 
39 34 
1-0059 
- 0-9941 
•1868 
•5021 
- -3153 
and Point Beaufort J 
6 
00 W.f 
0 
14 
28 
88 
3 15 
0-1239 
- 1-8761 
Rock Rapid 
and Montreal Island 
... 
29 
2 
16 E. 
00 W. 
2 
0 
29 
19 
56 
30 
87 
87 
39 34 
35 49 
1-0677 
01352 
- 0-9323 
- 1-8748 
-•0288 
•5025 
- -5313 
Fort Alexander 
15 
16 E.f 
27 
55 
38 
78 
53 37 
2-7003 
+ 0-7003 
•5096 
•5411 
- -0315 
and Fort Resolution 
29 
15 E.f 
21 
43 
42 
82 
3 9 
2-8546 
+ 0-8546 
Fort Alexander 
... 
15 
16 E.f 
23 
9 
47 
78 
53 37 
2-1794 
+ 0-1794 
•5909 
•5411 
+ -0498 
and Fort Resolution 
"... 
37 
20 E. 
17 
49 
1 
82 
3 9 
2-3021 
+ 0-3021 
Fort Reliance 
I- 
35 
19 E. 
10 
53 
26 
84 
1 0 
1-8357 
- 0-1643 
•7017 
•5079 
+ -1938 
and Rock Rapid 
r- 
29 
16 E. 
5 
41 
56 
87 
39 34 
2-4415 
+ 0-4415 
By an inspection of the numbers in the sixth column of this Table, which indicate 
the errors of the theoretical result, it will be seen that, with very few exceptions, 
there is not that accordance between the observations and the theory which, for the 
establishment of the theory, we ought to look for ; and that they rather indicate that 
although the theory maybe true as a first approximation, yet it requires considerable 
modification to render it accordant with the observations. The numbers in the ninth 
* I have not included the observations at New York and Montreal in this table, on account of the uncer- 
tainty which appears to attend the determination of the variation at those cities. The variation at New York, 
according to the Admiralty Chart, is 2° 30' W. Captain Bayfield found the variation at Vercheres, about 
twenty miles below Montreal, to be 10° 30' W . ; and we may from this assume 10° W. as the variation nearly 
at Montreal. These variations would give the place of the pole of convergence 7° 56' from New York, and 
3° 11' from Montreal. Such a result is so totally at variance with all others, that it would he absurd to insti- 
tute any comparison between conclusions drawn from it and any theoretical results. There can, I think, be 
no doubt that either the variation at New York is more than 2° 30' W., or that at Montreal less than 10° W., 
or that each of these is erroneous, the one in defect, the other in excess. This is one among many instances 
of the very vague determination of an important element in terrestrial magnetism at places where we might 
expect that it would have been determined with considerable precision ; and very forcibly points out the neces- 
sity of more accurate observations of the variation than we at present possess. 
f Variations observed in 1825 by Sir John Franklin. Captain Back did not observe the variation at those 
stations in the present expedition. The other variations are those observed by Captain Back in this expe- 
dition. 
I In the variations which Captain Back sent me, he has marked uncertain against this. The same uncer- 
tainty must apply to the variation at Montreal Island and Point Ogle. At Montreal Island the morning obser- 
vation gave the variation 2° 43' E., and the afternoon one 6° 42' W. ; the mean 2° W. At Point Ogle the 
variation by the morning observation was 1° 52' E., and by the afternoon one 1° 46' W. ; “the sun’s bearing 
at noon was first 180°, and after tapping the compass 183° 30'.” 
