228 
DR. C. CHREE: MAGNETIC DECLINATION 
Table XVI.—Ranges. Number of Occurrences in 11 Years. 
Month. 
0' to 
5'. 
5' to 
10'. 
10' to 
15'. 
15' to 
20'. 
20' to 
25'. 
25' to 
30'. 
30' to 
35'. 
35' to 
40'. 
>40'. l 
January . 
51 
145 
69 
37 
24 
7 
4 
3 
1 
February. 
26 
99 
84 
51 
26 
10 
4 
2 
8 
March 
1 
72 
138 
61 
32 
21 
8 
1 
7 
April 
0 
43 
167 
73 
27 
10 
6 
3 
1 
May 
0 
57 
157 
85 
20 
12 
3 
0 
7 
J une 
0 
56 
185 
67 
15 
1 
3 
1 
2 
July 
0 
59 
185 
70 
14 
5 
2 
2 
4 
August 
0 
37 
202 
75 
22 
1 
2 
0 
2 
September. 
1 
68 
153 
71 
19 
5 
4 
5 
4 
October. 
3 
103 
111 
67 
34 
10 
11 
2 
0 
November. 
42 
140 
81 
28 
14 
9 
8 
5 
3 
December. 
64 
166 
56 
29 
14 
7 
1 
1 
3 
7 Year .... 
188 
1045 
1588 
714 
261 
98 
56 
25 
42 
Sunns <i 
Winter.... 
183 
550 
290 
145 
78 
33 
17 
11 
15 
Equinox . 
5 
286 
569 
272 
112 
46 
29 
11 
12 
_ Summer . 
0 
209 
729 
297 
71 
19 
10 
3 
15 
larger than the mean for June. But this may arise in more than one way. It might 
signify an excess of range in most March days over most June days, or simply that of 
the comparatively small number of days of very large range a larger proportion occur 
in the former month than in the latter. 
To elucidate this point, the ranges for each month of each year were collected in 
groups, the first group containing all ranges not exceeding 5', the second group those 
exceeding 5' but not exceeding 10', and so on. Table XVI. summarises these results 
for the several months of the year. Totals are also given for the whole period and 
for the seasons. It seemed simpler to give the actual totals, hut any one using the 
table must remember to divide the figures by 11 if he wishes average results for the 
months and seasons of a single year. The total number of days included amounted 
to 4017, of these 1322 occurred in winter, 1342 in equinox, and 1353 in summer. 
The ranges exceeding 40' were so few and at the same time so variable that they 
have been combined to save space. The range exceeded 20' on 482 days, i.e., on 
almost exactly 12 per cent, of the days; but in March this percentage rose to 20, 
whereas in June it fell to 7. One was quite prepared to find that ranges exceeding 
20' are most numerous in the equinoctial months, but their greater frequency at 
midwinter than at midsummer was quite unexpected. 
Table XVII. is based on the same data as Table XVI., but arranges the results 
under the different years. It also gives means for the average year of the eleven, for 
the average of the years 1890, 1899, and 1900 of sunspot minimum, and for the 
average of the years 1 892 to 1895 of sunspot maximum. 
