% 
113 
Greenwich observations differ somewhat from those which 
I had derived from Mr. Bates’s short series, yet, nevertheless, 
when carefully examined and discussed, they also lead to 
the same general conclusion, that a connection exists 
between the daily variations of the rainfall and the daily 
movements of the declination magnet. Regarded in this 
relation, it will be apparent that the Greenwich series of 
observations possess a value much beyond that which is 
indicated by the results of Mr. Glaisher’s elaborate discussion. 
The mean hourly amounts of rainfall at 50 feet above the 
ground, as deduced by Mr. Glaisher from the Greenwich 
observations for the 
six years 
1861- 
-6 
are 
as follows : — 
h. 
h. 
in. 
h. 
h. 
in. 
0 
to 
1 
.. 0*552 
12 
to 
13 
0-649 
1 
?? 
2 
.. 0-638 
13 
55 
14 
.............. 0-622 
2 
?? 
3 
.. 0-722 
14 
55 
15 
0-585 
3 
?? 
4 
.. 0-698 
15 
55 
16 
0-780 
4 
5 
.. 0-821 
16 
55 
17 
0-689 
5 
>> 
6 
.. 0-519 
17 
55 
18 
.............. 0-685 
6 
?? 
7 
.. 0-439 
18 
55 
19 
0-592 
7 
V 
8 
.. 0-505 
19 
55 
20 
.............. 0-657 
8 
9 
.. 0-490 
20 
55 
21 
0-527 
9 
10 
.. 0-605 
21 
55 
22 
0-560 
10 
11 
.. 0-549 
22 
55 
23 
0-339 
11 
55 
12 
.. 0-569 
23 
55 
24 
0-456 
On looking over these numbers it will be seen that the 
least amount, ’339, occurs between 22h. and 23h., or in the 
hour immediately succeeding the moment when the mag- 
netic needle passes its mean position in the morning; and 
that the next amount in magnitude, ‘439, is between 6h. 
and 7h. or in the hour immediately following the needle’s 
passage through its mean position in the evening. Taking 
the two hours from 22h. to 24h. and the two from 6h. to 
8h., the sum of the amounts is T739, which is less than that 
of any four of the remaining 20 hours. Taking now the 
four hours from 21h. to lh. and the four hours from 5h. to 
9h., the sum of the amounts is 3‘860, which is less than that 
of any eight of the remaining sixteen hours. Next, taking 
the five hours from 20h. to lh. and the four from 5h. to 9h., 
