262 
DR. C. CHREE: DISCUSSION OF KEW MAGNETIC DATA 
The difference between the positions occupied by June in the B and B/ lists is 
remarkable. In the B list it comes first, slightly in advance of the other three mid¬ 
summer months, whereas in the Pd list no element places it higher than fifth. 
Another striking phenomenon is the difference between the positions assigned to 
March and July in the B' list according as the element considered is D or IT. In the 
case of H, it is true, the mean values of B/ for the six months March to September 
differ comparatively little. Still the fact that (July Bange/March Bange) = 0'88 for 
D, but = 1'06 for H, appears a little remarkable. 
Table XLII.—-Position of Months when Arranged in Descending Order of B and B'. 
January. 
F ebruary. 
March. 
April. 
1 
May. 
June. 
August. 
September. 
October. 
November. 
£ 
O 
o 
/•s 
W 
D 
11 
9 
7 
2 
4 
3 
5 
1 
6 
8 
10 
12 
R 
H 
11 
10 
8 
5 
4 
1 
2 
3 
6 
7 
9 
12 
Y 
11 
9 
6 
4 
1 
3 
2 
5 
7 
8 
10 
12 
Mean . 
11 
9 
7 
5 
(2) 
1 
(2) 
(2) 
6 
8 
10 
12 
D 
11 
8 
1 
2 
3 
9 
6 
5 
4 
7 
10 
12 
R' 
H 
11 
8 
6 
4 
2 
5 
1 
3 
7 
9 
10 
12 
V 
11 
7 
2 
4 
i 
5 
3 
6 
8 
9 
10 
12 
Mean . 
11 
8 
2 
(3) 
i 
(6) 
(3) 
5 
(6) 
9 
10 
12 
§ 27. In the case of the mean diurnal inequality for the year there is, as we have 
seen, a close connection between the range and the corresponding sunspot frequency 
S. This does not necessarily imply any close connection between sunspot frequency 
on any given day and the amplitude of the regular or irregular magnetic changes on the 
same day. It seems increasingly difficult to think of any cause for the magnetic diurnal 
inequality other than electrical currents in the upper atmosphere. In temperate 
latitudes, whether at sunspot maximum or minimum, regular magnetic changes are 
most rapid during the day, but the difference between day and night seems reduced 
at sunspot maximum. Whether by day or by night, the regular changes are larger 
in sunspot maximum than in sunspot minimum. The most natural inference is that 
direct sunlight, whether there are or are not sunspots, increases the conductivity of 
the upper atmosphere, and that the effect persists to some extent during the night. 
At sunspot maximum the upper atmosphere is more conducting than at sunspot 
minimum at the same hour. The state of the upper atmosphere as regards 
