268 
MAGNETIC SURVEY IN NORTH AMERICA. 
L. B.. 
Low temperatures. 
High temperatures. 
1843. 
t. 
V . 
6. 
<?■ 
1843. 
V. 
1 /. 
t. 
f- 
Jan. 17- 
34-4 
— 33 45-1 
75 13-4 
0-87923 
Jan. 17. 
62-9 
— 33 58-2 
75 13-4 
0-87814 
Feb. 1. 
26*2 
-33 35-1 
75 15-7 
0-88026 
Feb. 1. 
63-9 
-34 12-5 
75 15-7 
0-87715 
2. 
25-8 
-33 41*1 
75 15-7 
0-87976 
2. 
85-1 
— 34 18-7 
75 15-7 
0-87661 
3. 
27*8 
-33 30-6 
75 15-6 
0-88062 
3. 
80-4 
— 34 14-6 
75 15-6 
0-87697 
4. 
37*5 
-34 05-9 
75 15-6 
0-87765 
4. 
88-6 
—34 20-j 
75 15-6 
0-87651 
10. 
27-7 
-34 04*2 
75 14-7 
0-87776 
11. 
66-1 
-34 04-3 
75 14-7 
0-87775 
29-9 
-33 47-0 
75 15-1 
0-87921 
74-5 
0-87719 
Hence for L. B. ^=*00005. 
Table XL 
Abstract of the Observations made with Needle F. A. and F. C. to determine the 
Coefficient for the temperature correction. 
Needle F. A. 
Weight. 
1843. 
Low temperatures. 
High temperatures. 
Weight. 
1843. 
Low temperatures. 
High temperatures. 
t. 
V. 
t'. 
v'. 
t. 
V. 
f. 
■o'. 
r 
Jan. 4. 
26-0 
21 09-9 
60-8 
21 17*2 
Jan. 4. 
26-2 
26° 52-2 
61-5 
27 11-8 
4. 
28-0 
21 08-9 
56-8 
21 20-3 
4. 
27*4 
26 45-9 
57-1 
27 18-1 
12. 
35-2 
21 12-3 
74-2 
21 19-5 
12. 
35-5 
27 04-2 
74-8 
27 05-7 
2-0grs.< 
12. 
35-5 
21 21-8 
82-4 
21 25-6 
2-5 grs.< 
12. 
35-4 
27 00-3 
80-0 
27 11-3 
14. 
30-6 
21 09-5 
71-5 
21 32-1 
14. 
29-5 
26 53-1 
70-5 
27 12-9 
14. 
27-0 
21 12-6 
61-2 
21 20-8 
14. 
26-0 
26 58-8 
62-1 
27 02-1 
- 
16. 
33-5 
21 10-0 
72-7 
21 25-9 
l 
16. 
32-5 
27 08-4 
74-8 
27 18-1 
Means. . 
30-8 
21 12-1 
67-4 
21 23-1 
Means. . 
30-4 
26 57*6 
68-7 
27 11-4 
Jan. 4. 
26-7 
33 05-0 
61-2 
33 17-2 
4. 
26-2 
33 02-8 
58-8 
33 18-5 
3-0grs.< 
12. 
35-5 
33 21-6 
75-9 
33 26-0 
12. 
35-0 
33 15-2 
83-4 
33 25-8 
r 
Jan. 12. 
34-9 
46 45-4 
74-4 
46 52-5 
12. 
34-2 
33 14-8 
4-0 grs.< 
12. 
34-0 
46 42-1 
80-3 
47 05-6 
L 
16. 
32-5 
33 07-4 
78-2 
33 15-6 
L 
16. 
34-5 
46 41-4 
82-0 
47 15-4 
Means. . 
31-7 
33 11-1 
71-5 
33 20-6 
Means. . 
34-4 
46 43-0 
78-9 
47 04-5 
Hence, giving the observations with 4*0 grains, half the weight of the observations 
with each of the other three weights, we have ^=*000164. 
