230 
DR. C. CHREE: MAGNETIC DECLINATION 
Table XVIII.— Number of Occurrences of Maxima and Minima at Different 
Hours of the Day. 
Hour. 
Year. 
Winter. 
Equinox. 
Summer. 
Maxima. 
Minima. 
Maxima. 
Minima. 
Maxima. 
Minima. 
Maxima. 
Minima. 
0 to 1 
17 
338 
8 
189-5 
5 
97-5 
4 
51 
1 „ 2 
15 
142 
7 
56 
2 
48 
6 
38 
2 „ 3 
23 
98-5 
14 
34-5 
5 
36 
4 
28 
3 „ 4 
18 
84 
12 
23 
4 
35 
2 
26 
4 „ 5 
15 
56 
6 
16 
5 
16 
4 
24 
5 „ 6 
19 
173-5 
8 
17 
5 
18 
6 
138-5 
6 „ 7 
26 
376-5 
12 
5 
10 
39 
4 
332-5 
7 „ 8 
9 
554-5 
7 
15 
2 
155 
0 
384-5 
8 „ 9 
9 
507 
6 
77-5 
i 
286-5 
2 
143 
9 „ 10 
10 
100-5 
5 
45 • 5 
4 
45 
1 
10 
10 „ 11 
17-5 
9 
14 
1 
3-5 
1 
0 
0 
11 „ noon 
159 
0 
75 • 5 
0 
40-5 
0 
43 
0 
Noon „ 1 
1293-5 
0 
476 
0 
456-5 
0 
361 
0 
1 2 
1638-5 
0 
431 -5 
0 
639 
0 
568 
0 
2 „ 3 
518-5 
4 
121 
4 
116-5 
0 
281 
0 
3 „ 4 
96-5 
6 
26 
5 
24-5 
1 
46 
0 
4 „ 5 
33-5 
33 
23 
29 
2-5 
4 
8 
0 
5 „ 6 
28 
65 
20 
25 
2 
38 
6 
2 
6 „ 7 
20 
125 
18 
55 
9 
60 
0 
10 
7 „ 8 
4 
211-5 
2 
107-5 
1 
84 
1 
20 
8 „ 9 
5 
273 
2 
138-5 
9 
u 
105 ■ 5 
1 
29 
9 „ 10 
5 
283 
o 
O 
164 
1 
95 
1 
24 
10 „ 11 
4 
271-5 
0 
154 
2 
78 
2 
39-5 
11 ,, midt. 
7 
303-5 
4 
159 
2 
95-5 
i 
49 
Totals . 
3991 
4008 
1301 
1321 
1338 
1338 
1352 
1349 
§ 23. Considering the large excess of the average absolute range over the average 
inequality range, it is surprising to find that such a very large proportion of the 
maxima occur within 1-fr hours of the time of the maximum in the inequality range 
for the year. It is no less surprising to find that on no single day of the whole 
4008, for which information existed, did the minimum fall between 11 a.m. and 
2 p.m. In the case of the minima the frequency of occurrence shows an unmistak¬ 
able double period at all seasons; the maxima of frequency fall at about midnight, 
and between 7 and 9 a.m., the former being the more important in winter, but the 
latter at the other seasons. There is probably also a double period in the frequency 
of occurrence of the maxima, but the secondary maximum of frequency is very 
small, and a longer period of years would be required to show the exact hour of its 
occurrence at the different seasons. 
