126 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
At depth of 
i ft. 2 ft. 4 ft. 
Mean temperature of the soil at 9 a.m. . . . 45'i° 45'2° 44*3° 
Highest „ „ „ 49'5° 48-4° 46-1° 
Lowest „ „ „ 38-6° 40-2° 42-3° 
Mean relative humidity of the air at 9 a.m. (complete saturation being repre- 
sented by 100) 74 per cent. 
Rain fell on 7 days, to the total depth of 1-22 in. (equivalent to about 5| 
gallons of water to the square yard). Heaviest fall on any day 0-39 in., on the 
1 2th. 
The prevailing winds were north-easterly and south-westerly. 
The average velocity of the wind was 6 miles an hour. 
There were 168 hours of bright sunshine, equal to 4-1 per cent, of the greatest 
possible amount. 
There were 4 days on which no sunshine was recorded. 
May. — Generally speaking, this was a month of very dry weather, 
the rainfall being generally much below the usual amount. There 
were, however, exceptions to this rule in the southern portions of 
England, due almost entirely to one or two extremely heavy rain- 
storms, which from a gardener's point of view did more harm than 
good. One of these, which occurred in London on the 6th, caused a fall 
of over three inches of rain over a small but well-defined area ; whilst 
on two other days there were heavy falls over most of Surrey and 
Kent, varying from an inch to an inch and a half on both occasions, 
and together accounting at Wisley for more than two-thirds of the 
total rainfall of the month. The amount of sunshine was abundant 
and as a rule a good deal in excess of the average, and at Wisley there 
were but three entirely sunless days, including the two of heavy rain 
just referred to. The mean temperature for the month was above 
the average in the south, but the dominant north-easterly wind brought 
with it some " cold snaps " in the northern parts of the kingdom, 
and snow fell even over a portion of the Midlands. Night frosts, too, 
occurred three or four times at Wisley, sharp enough to injure tender 
vegetation, especially in those parts of the Garden which are sheltered 
from the wind. The frost which did most damage occurred during 
the early hours of the last day of the month, when Gunneras, potatos , 
beans, bracken, and other plants were very badly cut. 
The results obtained from the observations made at the Garden are 
shown in the following table : . 
Mean temperature of the air in shade . . . 53*9° 
Highest ,, 77 0 on the 26th 
Lowest ,, 33 0 on the nth 
,, ,, on the grass . . . . . . 22 0 „ nth 
Number of nights of ground frost ........ 5 
At depth of 
I ft. 2 ft. 4 ft. 
Mean temperature of the soil at 9 a.m. . . . 53*9° 52-7° 49-9° 
Highest „ „'„... 58-4° 56 0 52-6° 
Lowest „ „ „ 49-5° 49-5° 46-5° 
Mean relative humidity of the air at 9 A.M. (complete saturation being repre- 
sented by 100) 75 per cent. 
Rain fell on 9 days, to the total depth of 2-95 in. (equivalent to about 13! 
gallons of water to the square yard). Heaviest fall on any day 1-17 in., on the 
13th. 
The prevailing winds were north-easterly. 
The average velocity of the wind was 4 miles an hour. 
