ON “QUIET DAYS DURING THE ELEVEN YEARS 1890 TO 1900, ETC. 
391 
Table XXV.—Variation of Fourier Coefficients throughout the Year. 
Kew, 10 Years. 
Inclination. 
Vertical force. 
Cl. 
^ 2 - 
C3- 
Cl- 
C3. 
C 4 . 
January . 
40 
77 
64 
101 
45 
31 
29 
56 
February . 
53 
60 
90 
110 
56 
48 
67 
64 
March. 
86 
89 
124 
132 
89 
108 
140 
167 
April. 
125 
129 
120 
112 
131 
138 
154 
152 
May. 
145 . 
103 
95 
93 
172 
180 
150 
124 
June. 
144 
116 
95 
61 
148 
141 
87 
79 
July. 
140 
120 
85 
50 
167 
144 
104 
85 
August. 
150 
114 
139 
107 
119 
138 
140 
80 
September... 
128 
112 
167 
162 
116 
115 
128 
117 1 
October. 
103 
102 
125 
143 
84 
79 
113 
143 
November. 
66 
111 
71 
97 
44 
45 
52 
115 
December. 
20 
67 
25 
32 
29 
32 
36 
19 
Winter. 
44 
80 
64 
84 
43 
39 
46 
65 
Equinox . ... 
110 
104 
131 
140 
107 
110 
134 
149 
Summer. 
146 
116 
105 
76 
150 
151 
120 
86 
§ 34. Table XXVI. shows the relative importance of the four leading terms of the 
Fourier series in the case of the mean diurnal inequality for the year. The 
importance of the 12-hour term as compared to the 24-hour term appears decidedly 
greater in D, W, and V, which present remarkably similar features, than in H, IS or 
I, which resemble one another. 
Table XXVII. shows how the importance of the higher Fourier terms, as compared 
to the first, varies with the season of the year. In I and H the relative importance 
of the higher terms diminishes largely as we pass from winter to equinox, and also 
conspicuously as we pass from equinox to summer. 
In D and V, on the other hand, Co/cj and cjc-^ are greatest at the equinox, and cjci 
is decidedly greater in summer than in winter. The summer value of is as 
conspicuously small in D and V as in the other elements, but the equinoctial value is 
closely similar to the winter value. 
