METEOROLOGICAL OBSERVATIONS AT WISLEY, 1915. 125 
freezing, whilst a thermometer laid upon the grass, quite open to the 
sky, registered 22° of frost, the lowest reading throughout the winter. 
The amount of bright sunshine was again much less than usual for the 
season ; there were a few really bright days, but the average daily 
duration of sunshine at Wisley was under three hours, or only three- 
fourths of the average, whilst in some parts of Scotland it averaged 
nearly five hours, which is largely in excess of the normal amount. 
Under such adverse conditions vegetation was, as might have been 
expected, very backward ; trees and shrubs were very late in starting 
growth, and fruit trees did not bloom until from fourteen to twenty- 
one days after their time of blooming last year. 
The results obtained from the observations made at Wisley are 
shown in the following table : 
Mean temperature of the air in shade . . . . 41-4° 
Highest „ „„.... 58-2° on the 23rd 
Lowest „ „„.... 21-9° „ 29th 
on the grass n° 29th 
Number of nights of ground frost 19 
At depth of 
1 ft. 2 ft. 4 ft. 
Mean temperature of the soil at 9 a.m. . . . 41-2° 42-2° 42-8° 
Highest „ „ „ 45-6° 44-2° 43-6° 
Lowest „ „ „ 37-2° 40-0° 41-6° 
Mean relative humidity of the air at 9 a.m. (complete saturation being repre- 
sented by 100) 86 per cent. 
Rain fell on 10 days, to the total depth of 0*73 in. (equivalent to about 3^ 
gallons of water to the square yard). Heaviest fall on any day 0-23 in., on the 
2nd. 
The prevailing winds were from between north and north-east and west and 
south-west. 
The average velocity of the wind was 5^ miles an hour. 
There were 87 hours of bright sunshine, equal to 24 per cent, of the greatest 
possible amount. 
There were 6 days on which no sunshine was recorded. 
April. — During the earlier part of this month the weather continued 
cold and unsettled, with occasionally a strong wind, and it was not 
until the middle of the month that a normal temperature and condi- 
tions favourable for garden work had become developed. Even then, 
however, the nights continued cold, with low temperatures on the 
ground, and to this was probably due the very slow germination of 
seeds which was noticed ; it was not until the middle of the month 
that the temperature at Wisley rose to 60 degrees, and there was a 
sharp frost on the ground so late as the night of the 24th. The south- 
east of England was favoured with more than its usual amount of 
sunshine, and in this respect was better off than some other districts ; 
and it was also again a dry month throughout England, so that on 
the whole the weather of the month may be fairly described, so far as 
the neighbourhood of Wisley is concerned, as fine and dry. 
The results obtained from the observations made at Wisley are 
shown in the following table : 
Mean temperature of the air in shade . . . .47-4° 
Highest „ „ „ .... 71 0 on the 30th 
Lowest ,, „„.... 28 0 ,, 24th 
,, ,, on the grass . . . . 17 0 ,, 1st 
Number of nights of ground frost , , » » . . . .14 
