VARIATION OP TERRESTRIAL MAGNETISM. 
483 
four observing stations. The numbers vyliich I have computed for this purpose are 
given in Table X. 
In that table T/ stands for 
dfji} 
I sin*^ 
where jx = cos u and is the zonal harmonic ot degree id. 
Table VIII.—Comparison between observed and calculated coefficients of West 
force. 
Bombay 
Lisbon . 
Greenwich . 
St. Petersburs 
f4,. 
K 
a 
Jo, 
Observed. 
Calcu¬ 
lated. 
Observed, 
Calcu¬ 
lated. 
Observed, 
Calcu¬ 
lated. 
Observed. 
Calcu¬ 
lated. 
Summer . 
+ 
58 
+ 
58 
+ 
116 
+ 
124 
+ 
132 
124 
+ 
60 
+ 
73 
Winter 
0 
— 
4 
+ 
32 
+ 
41 
+ 
4 
+ 
8 
+ 
23 
+ 
39 
Mean . 
+ 
29 
+ 
27 
+ 
74 
+ 
82 
+ 
68 
+ 
66 
+ 
41 
+ 
56 
Summer . 
+ 
74 
+ 
88 
+ 
225 
+ 
232 
+ 
108 
+ 
90 
+ 
158 
+ 
172 
Winter 
+ 
87 
+ 
52 
+ 
119 
+ 
112 
+ 
31 
+ 
10 
+ 
104 
+ 
105 
Mean . 
+ 
80 
+ 
70 
+ 
172 
+ 
172 
+ 
70 
+ 
50 
+ 
131 
138 
Summer . 
+ 
85 
+ 
91 
+ 
233 
+ 
255 
+ 
83 
85 
+ 
135 
+ 
149 
Winter 
+ 
105 
-f 
95 
+ 
115 
+ 
113 
+ 
1 
— 
5 
+ 
87 
+ 
104 
Mean . 
+ 
95 
+ 
93 
+ 
174 
+ 
184 
+ 
42 
+ 
40 
+ 
111 
+ 
127 
Summer . 
+ 
100 
+ 
79 
+ 
225 
+ 
229 
+ 
99 
+ 
92 
115 
+ 
100 
Winter 
+ 
92 
+ 
121 
+ 
96 
93 
— 
15 
— 
6 
+ 
69 
+ 
72 
Mean . 
+ 
96 
+ 
100 
+ 
161 
+ 
161 
+ 
42 
+ 
43 
+ 
92 
+ 
87 
Bombay 
Lisbon 
Greenwich 
St. Petersburg . 
Mean of year 
” 
>5 
5i 
«3- 
K 
rtj. 
h- 
Obsei ved. 
Calcu¬ 
lated. 
Observed. 
Calcu¬ 
lated. 
Observed. 
Calcu¬ 
lated. 
Observed. 
Calcu¬ 
lated. 
+ 71 
+ 63 
+ 41 
- 12 
-f- 19 
+ 108 
+ 82 
- 7 
+ 8 
+ 57 
+ 44 
- 8 
- 24 
+ 88 
-h 74 
+ 16 
-h 24 
-h 24 
+ 17 
- 18 
+ 20 
+ 21 
+ 31 
- 20 
- 14 
+ 8 
-h 14 
- 1 
- 12 
+ 5 
+ 21 
+ 27 
3 Q 2 
