115 
The mean hourly rainfall is 32*86mm. A principal 
mininum takes place during the two hours immediately 
following the passage of the magnetic needle through its 
mean position in the forenoon, namely from 22h. to 24h. ; 
and a secondary minimum during the two hours imme- 
diately preceding the afternoon passage, namely from 4h. 
to 6h. The mean amount per hour during these fnur hours 
is 27’40, or 5* 46 below the general mean. 
Taking the two hours before and the four hours after 
each passage the mean hourly amount for these twelve hours 
is 29 ‘80, while the mean hourly amount for the remaining 
twelve hours is 35*92. 
It appears, therefore, that at Lisbon, as well as at Green- 
wich, the curve of daily rainfall has two maxima and two 
minima, the times of minima corresponding with or very 
closely following those when the declination magnet is in 
its mean position. The six consecutive hours of greatest 
rainfall, both at Greenwich and Lisbon, are from 14h. to 20h. 
The twelve consecutive hours of greatest fall are from 9h. 
to 21h. at Greenwich, and from lOh, to 22h. at Lisbon. 
During this period the north end of the declination magnet 
is to the east of its mean position, and the wind passes 
through its phase of minimum velocity. 
Comparing the amounts of rain which fall at both Green- 
wich and Lisbon during the two maximum and the two 
minimum periods of the day we have the following results : 
s 
Amount 
at 
Green- 
wich. 
Mean 
Hourly 
Amount 
Ratio 
to 
Mean 
Hourly 
Amount 
for the 
Entire 
Day. 
Amount 
at 
Lisbon. 
Mean 
Hourly 
Amount 
Ratio | 
to 
Mean 
Hourly 
Amount 
for the 
Entire 
Day. 
h. h. 
in. 
in. 
mm. 
mm. 
1 
1 
1st max 
1 to 5 
2-879 
•719 
1-19 
124-7 
31-17 
0-94 
1st min 
5— 9 
1-953 
•488 
0-82 
121-7 
30-42 
0-92 
2nd max 
9 — 20 
6-982 
•634 
1-06 
393-65 
35-78 
1-08 
2nd min 
20—1 
2-434 
•483 
0-82 
148*65 
29-73 
0-90 
From the numbers in columns 5 and 8 it will be seen 
