METEOROLOGICAL OBSERVATIONS AT WISLEY, 1916. 99 
Mean relative humidity of the air at 9 a.m. (complete saturation being repre- 
sented by 100), 76 per cent. 
Rain fell on 12 days, to the total depth of 098 in. (equivalent to about 4^ 
gallons of water to the square yard). Heaviest fall on any day 0-23 in., on the 
19th. 
The prevailing winds were northerly — from north-west to north-east. 
The averaga velocity of the wind was 7 miles an hour. 
There were 193 hours of bright sunshine, equal to 47 per cent, of the greatest 
possible amount. 
There were no days on which sunshine was not recorded. 
May. — Nearly the whole of the first half of this month was dull 
and sunless, and with the exception of one or two days of exceptional 
warmth, it was cool for the time of year. The second half, however, 
brought with it a marked change, and it was both drier and brighter, 
and very much warmer than usual, so much so, indeed, that, notwith- 
standing the cool first half, the mean temperature for the whole month 
was considerably above the average. On the 21st the shaded ther- 
mometer at the Gardens registered 80 °, whilst in London 85 0 was 
recorded. The latter half of the month was also very dry over the 
whole of the eastern and south-eastern counties, but taking the month 
as a whole the fall of rain was more or less in excess of the average all 
over the kingdom. To this condition of things not only did vegetation 
quickly respond, but insect life also became very active, the eggs of 
some pests being hatched out at so great a rate as to play havoc 
with the foliage of nearly all deciduous trees. There were no frosts 
all through the month. 
The mean results of the daily readings of the instruments at the 
Gardens are given in the following table : 
Mean temperature of the air in shade . ... .54-7° 
Highest „ 8o° on the 21st 
Lowest „ „ „ 35 0 „ 27th 
„ „ on the grass . . . .24°,, 27th 
Number of nights of ground frost ....... 9 
At depth of 
1 ft. 2 ft. 4 ft. 
Mean temperature of the soil at 9 a.m. . . . 54*2° 49*8° 49'8° 
Highest „ „ „ . . . 59 0 5 6° 53° 
Lowest „ „ 495 0 50 0 47 0 
Mean relative humidity of the air at 9 a.m. (complete saturation being repre- 
sented by 100), 76 per cent. 
Rain fell on 11 days, to the total depth of 176 in. (equivalent to about 8J 
gallons of water to the square yard). Heaviest fall on any day 0 40 in., on the 
12th. 
The prevailing winds were westerly. 
The average velocity of the wind was 5 miles an hour. 
There were 195 hours of bright sunshine, equal to 41 per cent, of the greatest 
possible amount. 
There were 4 days on which no sunshine was recorded. 
June. — The weather of this month was altogether abnormal, and 
as regards temperature it is probably safe to say that so cold a June 
had not been experienced for at least three quarters of a century. All 
over England and Wales, and in parts of Scotland and Ireland, there 
was a great deficiency of bright sunshine, and in consequence a con- 
tinued succession of low maximum temperatures day after day, and to 
this, perhaps more than to low night temperatures, the very low 
