128 
J. HOPKINSON-CLIMATE OF HEETFOBDSHIEE. 
wet days in Spring. Winter is by far the most cloudy season, 
although, in these twelve years it has had much less rain than 
either Summer or Autumn ; hut this period is very much too short 
for any conclusions as to rainfall to he founded upon it. Autumn 
has lately been a much wetter season than it usually is, owing to 
heavy rain in October and November. 
Eesults of Climatological Obseevations foe each Season 
(Means for the County , with Extremes of Temperature ), 
1887-1898. 
Seasons 
Temperature of the Air 
Humidity 
Cloud, 0-10 
Fain 
Means 
Extremes 
Amount 
Days 
Mean 
Min. 
Max. 
Bange 
Min. 
Max. 
0 
O 
O 
O 
O 
0 
% 
ins. 
Spring . 
46-6 
37*5 
557 
1 8'2 
9-0 
86-6 
79 
6*5 
5*03 
39 
Summer.. 
6 o ‘2 
5° *4 
70*0 
19*6 
29*0 
94*5 
75 
6-6 
6-94 
40 
Autumn. 
49-2 
41 -8 
56*6 
r 4*8 
15-0 
91 *8 
86 
6-6 
7-26 
45 
Winter . 
37'2 
31*7 
427 
II'O 
I'O 
65*3 
89 
7 *2 
5*04 
44 
The monthly results follow, first for the County and then for 
each station. The mean temperature is seen to increase very little 
from January to February, but then with gradually increasing 
rapidity to June ; it remains nearly stationary to August, decreases 
at about the average rate per month to September, then at twice 
the average rate to October, and at a little above the average to 
December. If we assume that the middle of each month has about 
the average temperature of the month, the rate of increase and 
decrease given above will give approximately the rate from the 
middle of one month to that of another. Although the range of 
temperature generally increases as the weather becomes warmer, 
and vice versa , the warmest month has not the greatest mean daily 
range, for this increases more rapidly than the temperature, and 
reaches its maximum in June. The greatest absolute range of tem¬ 
perature is in September and the next in May, the former chiefly 
owing to warm days and the latter to cold nights. The air is as 
a rule driest in the warmest months, but the mid-vernal month, 
April, although much colder than the mid-autumnal month, October, 
has as much as 9 per cent, less relative humidity. A remarkable 
feature of the rainfall of these twelve years is that it has been 
50 per cent, greater on the average in the last half of the year 
than in the first half. There have been falls during this period of 
at least 2^ ins. in twenty-four hours on twelve occasions. On the 
12th of July, 1889, such a fall occurred at 18 stations out of 30 
then recording, and at least 3^ ins. at 4 of these. Falls of at least 
3 ins. have occurred on seven occasions, and of at least 3^ ins. on 
12th July, 1889, the day with the greatest average rainfall in the 
county, and on 17th July, 1890, the day with the greatest fall at 
any one station, viz., 4T9 ins. at Moor Park, Eickmansworth. 
