314 
DR. S. CHAPMAN ON THE LUNAR DIURNAL VARIATION OF THE 
Table IVb. —Fourier Coefficients of the Lunar Diurnal Magnetic Variations, 
Reduced to the Epoch of New Moon. 
Pavlovsk. Vertical Force. 
The unit of force is 10 -7 C.G.S. ; the small corrections mentioned in §§ 5, 6 have not 
been applied at this stage, cf. § 9 ; + means increasing downward force. 
Season. 
Lunar 
phase. 
a\. 
b\. 
$2* 
h. 
a'z. 
^3- 
a'i. 
b\. 
r 
1 
39 
38 ■ 
- 15 
31 
11 
4 
3 
-10 
2 
-76 
28 
4 
29 
16 
_ 2 
-19 
8 
3 
-34 
-20 
6 
- 2 
4 
5 
- 4 
- 9 
Summer . . 
5 4 
-70 
55 
24 
88 
10 
- 1 
30 
19 
10 
37 
- 4 
- 9 
9 
3 
7 
- 9 
6 
7 
- 14 
34 
- 4 
13 
- 1 
- 1 
9 
7 
- 10 
17 
13 
- 5 
5 
- 8 
- 5 
- 15 
- 
8 
-63 
78 
- 6 
- 3 
- 15 
- 6 
9 
10 
Mean. . 
-19 
30 
6 
12 
10 
- 3 
- 1 
- 1 
i 
10 
34 
- 9 
-30 
8 
- 10 
10 
8 
2 
58 
-20 
31 
- 19 
1 
1 
- 9 
4 
3 
-53 
-47 
-28 
- 17 
- 13 
17 
4 
7 
Equinox . 
4 
-26 
55 
- 8 
13 
9 
3 
- 12 
5 
5 
- 9 
- 13 
- 16 
-30 
15 
0 
7 
- 11 
6 
82 
-67 
3 
- 5 
- 2 
-28 
15 
3 
7 
-54 
-46 
- 10 
-34 
- 22 
- 6 
13 
8 
-- 
8 
-84 
35 
- 3 
- 8 
- 1 
12 
1 
- 1 
Mean. . 
- 10 
- 9 
- 5 
- 16 
- 1 
- 1 
4 
3 
- 
1 
33 
34 
- 4 
11 
- 6 
- 8 
- 14 
0 
2 
19 
29 
30 
39 
4 
17 
3 
- 1 
3 
12 
-60 
-26 
- 1 
17 
12 
- 7 
6 
Winter . . - 
4 
5 
-57 
85 
14 
30 
- 8 
4 
41 
0 
- 12 
- 1 
10 
0 
3 
- 6 
- 1 
3 
6 
38 
-40 
- 6 
- 18 
4 
3 
- 6 
- 3 
7 
29 
-38 
- 10 
- 1 
21 
- 25 
- 1 
- 14 
8 
49 
-28 
3 
-28 
- 10 
- 11 
6 
- 9 
Mean. . 
26 
- 7 
- 2 
5 
2 
0 
- 3 
- 2 
