REPORT ON METEOROLOGICAL OBSERVATIONS, WISLEY, 191 7. 325 
locale of heaviest fall of rain, passing over Holland House, Kensington. 
The second storm occurred on the night of the 28th in Somerset, 
when there fell at Bruton 9-84 in. of rain, the largest daily fall hitherto 
recorded in Great Britain. It is perhaps unnecessary to point out 
that such storms as these quite upset the normal averages for the 
districts in which they occur. The weather conditions of the month, 
although at no time really settled, were on the whole favourable for 
the development of plant growth, and at Wisley everything made 
extraordinary progress, although, owing to the forcing character 
of the weather, the flowers were over very quickly. 
The mean climatological results obtained at Wisley are given in 
the appended table : 
Mean temperature of the air in shade 
Highest ,, 
Lowest ,, 
Lowest „ on the grass 
Number of nights of ground frost . 
6i-6° 
89 0 on the 17th 
42 0 23rd 
32 0 23rd 
1 
At depth of 
1 ft. 2 ft. 4 ft. 
Mean temperature of the soil at 9 a.m. . . . 61-3° 59'5° 557° 
Highest „ 65 0 62 0 57 0 
Lowest „ „ 59° 57° 53° 
Mean relative humidity of the air at 9 a.m. (complete saturation being repre- 
sented by 100), 70 per cent. 
Rain fell on 10 days, to the total depth of 2*28 in. (equivalent to about 10 J 
gallons of water to the square j^ard). Heaviest fall on any day 1*51 in., on the 
28th. 
The prevailing winds were from between south-west and north-west. 
The average velocity of the wind was 4! miles an hour. 
There were 213 hours of bright sunshine, equal to 44 per cent, of the greatest 
possible amount. 
There was but one day on which no sunshine was recorded. 
July. — The weather conditions of this month were fairly normal, 
its chief outstanding features being a marked excess of bright sun- 
shine, and a less notable excess of warmth. There were some occasional 
cool nights, and except over a few districts in the North, now and again 
slight ground frosts, but fortunately these were not sufficiently severe 
to do much damage to vegetation. In addition the month was 
unusually dry over the northern half of the kingdom, but less so in 
the south, and particularly the south-east, of England, where, owing 
to some heavy downpours during its closing days, the normal fall 
was largely exceeded. At Wisley, and over the Thames valley districts 
generally, the total for the month was between twice and three times 
the usual amount ; but the absence of rain during the earlier weeks 
had been the cause of much trouble in the Gardens, many plants, and 
more especially strawberries, suffering greatly from drought. 
The mean results of the Wisley observations are given in the 
following table : 
Mean temperature of the air in shade 
Highest ,, 
Lowest ,, 
Lowest „ on" the grass 
Number of nights of ground frost , 
61 -8° 
79° on the 14th 
45° » 1 oth 
35° „ 10th 
. nil 
