310 
DR. S. CHAPMAN ON THE LUNAR DIURNAL VARIATION OF THE 
Table IIb. —Fourier Coefficients of the Lunar Diurnal Magnetic Variations, 
Reduced to the Epoch of New Moon. 
Pavlovsk. Horizontal 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 ; + denotes increasing horizontal force. 
Season. 
Lunar 
phase. 
a'i- 
b\. 
a 2 . 
h. 
a’ 3 . 
V t . 
a’i. 
b\. 
1 
- 3 
90 
- 2 
103 
- 8 
61 
— 99 
Li Li 
9 
2 
19 
107 
12 
104 
- 14 
82 
-22 
- 2 
3 
- 30 
6 
-25 
80 
-39 
23 
-19 
1 
Summer . . 
4 
62 
55 
23 
77 
- 13 
79 
- 22 
7 
5 
43 
26 
36 
141 
10 
75 
-35 
- 2 
6 
29 
106 
- 6 
167 
27 
69 
-69 
0 
7 
53 
2 
Li 
30 
71 
21 
46 
5 
7 
- 
8 
4 
51 
22 
88 
- 10 
50 
0 
23 
Mean. . 
22 
55 
ii 
104 
- 3 
61 
-23 
5 
r 
1 
- 102 
- 2 
40 
76 
- 5 
60 
23 
13 
2 
■ 55 
66 
-41 
11 
18 
61 
-34 
15 
3 
90 
84 
11 
66 
13 
5 
6 
9 
Equinox . . 
4 
42 
- 1 
- 1 
73 
-33 
79 
- 22 
26 
5 
- 49 
46 
- 17 
- 8 
- 10 
77 
- 10 
34 
6 
15 
43 
-48 
5 
1 
46 
- 5 
56 
7 
10 
38 
36 
78 
50 
99 
-29 
27 
- 
8 
- 27 
48 
26 
86 
- 5 
68 
1 
7 
Mean. . 
- 10 
40 
1 
48 
4 
62 
- 9 
23 
r 
1 
45 
- 39 
-29 
- 32 
- 1 
-28 
13 
- 1 
2 
- 77 
43 
-49 
4 
- 16 
10 
- 1 
-11 
3 
■ 57 
0 
- 54 
8 
- 30 
- 7 
12 
- 3 
Winter . . 
. •< 
4 
5 
- 18 
9 
- 55 
- 30 
-23 
8 
0 
- 20 
-34 
-40 
- 6 
— 2 
12 
-34 
2 
7 
6 
- 35 
- 23 
3 
- 17 
-42 
i 
-18 
13 
7 
49 
- 27 
-16 
- 31 
10 
- 12 
- 11 
20 
- 
8 
90 
1 
11 
28 
6 
-17 
29 
- 9 
Mean. . 
1 
- 16 
-19 
- 8 
-18 
- 8 
0 
2 
