208 
DR. C. CHREE: MAGNETIC DECLINATION 
as one storm all groups of successive disturbed days we have 125 storms, two of them 
extending from one month to the next. The distribution of these and Mr. Maunder’ s 
storms in the different years is shown in Table I. The difference between the totals 
Table I.—Disturbances. 
Disturbances at Kew. 
Year. 
Storms at Greenwich, 
Number of days. 
Number of storms. 
after Maunder. 
1890 
6 
3 
7 
1891 
22 
12 
14 
1892 
30 
18 
26 
1893 
11 
7 
20 
1894 
21 
14 
16 
1895 
19 
14 
11 
1896 
39 
18 
18 
1897 
14 
11 
11 
1898 
19 
12 
12 
1899 
20 
11 
12 
1900 
8 
5 
3 
Total .... 
209 
125 
150 
for Kew and Greenwich arises of course simply from the method of selection. A 
considerable number of days treated as “ ordinary ” at Kew would fairly rank as days 
of disturbance when regarded from the standpoint either of the amplitude or the 
number of the oscillatory movements, and would most naturally be classified as dis¬ 
turbed for purposes such as those of Mr. Maunder, The chief difference in the totals 
is for 1892 and 1893, especially the latter year. In 1893, sunspots were at their 
maximum, and the regular diurnal range was very large. A comparatively trifling 
disturbance might suffice to bring the range over 20', which Mr. Ellis treats, at 
least roughly, as a minimum value for a disturbance ; thus, when main importance 
was assigned to the amplitude of the range, it was only natural to reach a larger 
number for the disturbed days in 1893 than when attention was directed to the 
greater or less abnormality of the curve. As compared to the two adjacent years, 
1893 was, in fact, remarkable for the extraordinary absence of irregular movements. 
§ 6. Table II. gives the distribution of the disturbances and disturbed days 
throughout the year, with corresponding data from Mr. Maunder’s list; it also gives 
some particulars as to the amplitudes of the movements. In two cases, March- 
April, 1891, and January-February, 1896, where successive disturbed days belonged 
to two different months, the disturbance has been counted as two. In the second of 
these cases six successive days were treated as disturbed ; no other sequence of 
disturbed days exceeded four. The Kew data in Table II. give a smoother annual 
