424 
ON THE INEQUALITIES OE TEEEESTEIAL MAGNETISM. 
LUNO-MENSTEUAL AND LUNO-DIUENAL INEQUAITIES OF YEETICAL FOECE. 
The luno-menstrual inequality has been investigated ; but the resulting numbers are 
small and uncertain, and it does not appear necessary to insert them here. 
The luno-diurnal inequality for the period 1858-1863, expressed in terms of the 
horizontal force, is found to be as follows : — 
Lunar 
Hour. 
Inequality of Vertical 
Force, in terms of 
Horizontal Force. 
Lunar 
Hour. 
Inequality of Vertical 
Force, in terms of 
Horizontal Force. 
Lunar 
Hour. 
Inequality of Vertical 
Force, in terms of 
Horizontal Force. 
0 
+ 0-000005 
8 
-0-000120 
16 
+ 0-00008 
1 
+ 
18 
9 
— 
77 
17 
— 
18 
2 
+ 
64 
10 
— 
33 
18 
— 
64 
3 
+ 
26 
11 
— 
51 
19 
+ 
20 
4 
+ 
43 
12 
+ 
20 
20 
— 
38 
5 
+ 
33 
13 
+ 
38 
21 
— 
26 
6 
— 
84 
14 
+ 
95 
22 
+ 
97 
7 
— 
110 
15 
+ 
69 
23 
+ 
102 
On comparing these numbers with the corresponding numbers for the period 1849- 
1857 (Greenwich Magnetical and Meteorological Observations, 1859, page ccxxxvi), 
there appears to be sufficient resemblance between them to induce us to combine them. 
The general mean is as follows : — 
Luno-diurnal Inequality of Vertical Force, for the period 1849-1863. 
Lunar 
Hour. 
Inequality of Vertical 
Force, in terms of 
Horizontal Force. 
Lunar 
Hour. 
Inequality of Vertical 
Force, in terms of 
Horizontal Force. 
Lunar 
Hour. 
Inequality of Vertical 
Force, in terms of 
Horizontal Force. 
0 
+ 0-000011 
8 
— 0 000078 
16 
+ 0-000049 
1 
+ io 
9 
— 
76 
17 
+ 
61 
2 
+ 16 
10 
— 
33 
18 
+ 
31 
3 
— 20 
11 
— 
51 
19 
— 
8 
4 
— 12 
12 
_ 
23 
20 
— 
18 
5 
53 
13 
+ 
10 
21 
- 
6 
6 
74 
14 
+ 
60 
22 
+ 
47 
7 
- 11 
15 
+ 
79 
23 
+ 
104 
These numbers may be rudely resolved into a Luno-diurnal term and a Luno-semi- 
diurnal term, in the following form : — 
Luno-diurnal Inequality of Vertical Force, for the period 1849-1863. 
Lunar 
Hour. 
Luno-diurnal 
term. 
Luno- 
■semidiurnal 
term. 
Lunar 
Hour. 
Luno-diurnal 
term. 
Luno-semidiurnal 
term. 
0 
+ 0-000017 
-0-000006 
12 
-0-000017 
-0-000006 
1 
0 
+ 
10 
13 
0 
+ 
10 
2 
— 22 
+ 
38 
14 
+ 
22 
+ 
38 
3 
— 50 
+ 
30 
15 
+ 
50 
+ 
30 
4 
— 31 
+ 
19 
16 
+ 
31 
+ 
19 
5 
- 57 
+ 
4 
17 
+ 
57 
+ 
4 
6 
- 53 
— 
21 
18 
+ 
53 
— 
21 
7 
— 1 
— 
10 
19 
+ 
1 
— 
10 
8 
- 30 
— 
48 
20 
+ 
30 
— 
48 
9 
- 35 
— 
41 
21 
+ 
35 
— 
41 
10 
- 40 
+ 
7 
22 
+ 
40 
+ 
7 
11 
- 77 
+ 
26 
23 
+ 
77 
+ 
26 
The numbers do not appear sufficiently regular to justify the examination with refer- 
ence to the classification of the years by large solar curves and small solar curves. 
