TERRESTRIAL MAGNETISM AT KEW OBSERVATORY. 
81 
Absolute daily ranges, however, are affected by disturbance in a much greater 
degree than inequality ranges derived from all days of the year, so some direct 
confirmation was desirable. It was obtained as follows : The monthly groups of 10 
days already employed in connection with the D ranges, were utilized for H ranges, 
for the 3 years 1892, 1893, and 1894, which were the years of largest sunspot frequency 
between 1890 and 1900. The investigation was limited to the representative day n 
of largest (or least) sunspot area, and the three immediately following days n + \,n-\-2, 
and n + 3. 
The results derived by meaning the several columns for the three years separately 
appear in Table II. Each entry, it will be understood, represents a mean derived from 
10x12 or 120 days. 
Table II.-—Comparison of D and H results from 10-day Groups. 
Days of large spot area. 
Yearly 
Days of small spot area. 
Element. 
Year. 
mean 
from all 
n. 
n + 1 . 
r^-t- 2. 
«. + 3. 
days. 
n. 
71+1. 
71 + 2. 
71 + 3. 
.i> J 
(unit T) I 
1892 
16-96 
17-96 
18-75 
19-74 
17-70 
16-23 
15-96 
16-01 
15-96 
1893 
15-37 
15-91 
16-32 
16-35 
15-62 
15-39 
15-28 
15-17 
15-33 
1894 
17-73 
18-05 
18-11 
18-19 
16-50 
15-06 
14-58 
14-88 
15-14 
Mean . . 
— 
16-69 
17-31 
17-73 
18-09 
16-61 
15-56 
15-27 
15-35 
15-48 
H [ 
(unit ly) I 
1892 
84-4 
88-5 
91-7 
101-2 
84-0 
73-4 
71-0 
71-0 
68-0 
1893 
70-9 
73-1 
75-4 
76-0 
69-7 
69-1 
66-1 
63-9 
65-8 
1894 
86-8 
91-5 
91-8 
95-1 
81-4 
69-1 
69-1 
71-3 
73-1 
Mean . . 
— 
80-7 
84-4 
86-3 
90-8 
78-4 
70-5 
68-7 
68-7 
69-0 
Expressing the algebraic excess of each of the 3-year means in the columns n,n-\-l, 
n + 2, and ?^-f-3 over the corresponding means from all days of the year (viz., 16''61 for 
D and 78'4y for H) as percentages of the latter mean values, we obtain the results 
given in Table III. 
Table III.—D and H results from 10-day Groups, as Percentages. 
Element. 
Group of days of large spot area. 
Group of days of small spot area. 
n. 
71+ 1. 
71+2. 
11 + 3. 
77. 
77+1. 
77+2. 
77+3. 
I) . . . . 
II ... . 
+ 0-5 
+ 3-0 
+ 4-2 
+ 7-7 
+ 6-7 
+ 10-1 
+ 9-0 
+ 15-8 
- 6-3 
- 10-0 
- 8-0 
- 12-3 
- 7-5 
- 12-3 
1 
- 6-8 
-12-0 i 
VOL. ccxii.— A. M 
