320 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
of this month, there had been forty-two consecutive days of ground 
frost ; and during the latter half the ground temperature varied 
from between 12 ° below freezing to a maximum of 7 0 above. 
It was again a dull month generally with less than the average 
amount of sunshine everywhere, with the exception of the north 
of Scotland and the south-west of England : in these two districts, at 
Fig. 52. — Relative Frequency of Winds from Different 
Points of the Compass at Wisley 191 7. 
The black circle represents calms. 
the opposite extremes of the kingdom, the amount registered rather 
exceeded the average. 
The Wisley results are as follows : 
Mean temperature of the air in shade . . . . 34*2° 
Highest „ „,,.... 50 0 on the 27th 
Lowest 5 0 ,, 7th 
Lowest „ on the grass ..... — 4 0 7th 
Number of nights of ground frost . . . . . . . .21 
Mean temperature of the soil at 9 a.m. . 
Highest ,, . 
Lowest ,, ,, ,, 
4 ft. 
39-2° 
4i° 
38° 
At depth of 
1 ft. 2 ft. 
• * • 35*3° 36-7° 
41° 40° 
32° 35° 
Mean relative humidity of the air at 9 a.m. (complete saturation being repre- 
sented by 100), 89 per cent. 
Rain or snow fell on 10 days, to the total depth of 0-76 inches (equivalent to 
about 3 J gallons of water to the square yard) . Heaviest fall on any day 0-28 in., 
on the 4th. 
The prevailing winds were easterly, but light and variable. 
The average velocity of the wind was only a quarter of a mile an hour. 
There were 40 hours of bright sunshine, equal to 14 per cent, of the greatest 
possible amount. 
There were 10 days on which no sunshine was recorded. 
March. — An unusual degree of cold was again the outstanding 
feature of the weather of this month, as it had been of its three im- 
mediate predecessors, the mean temperature being generally about 
