56 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY, 



however, was so cold that it produced the lowest temperature of the 

 month! With the exception of this " cold snap" the temperature 

 continued fairly uniform and close to the average throughout. The 

 warmest days occurred towards the close, and on the 29th the screened 

 thermometer at Wisley rose to 69 degrees, the daily range being as a 

 rule small. The month was, however, a wet one, and over nearly the 

 whole kingdom the fall of rain was above the average, in some parts 

 exceeding it by more than 100 per cent. ; the exception to this state 

 of things was found in the extreme north-east, where the fall of rain 

 was less than the average. Generally speaking, the month was a 

 dull one, very few districts receiving its usual quota of sunshine, and 

 some usually sunny parts — the southern counties and the Channel 

 Islands — getting little more than half their usual amount of sun. 

 The unusual warmth of the 29th was followed in the evening by a 

 thunderstorm of rare magnificence, in which the Hghtning-fl ashes 

 succeeded each other with startling rapidity. 



The records at Wisley show : 

 Mean temperature of the air in shade .... 47" 0° 



Highest „ „„„.... 69° on the 29th 



Lowest „ „ „ „ ,, . . . 27° „ 13th 



Lowest on the grass , . . . . 22° „ 13th 



Number of nights of ground frost ........ 7 



At depth of 

 I ft. 2 ft. 4 ft. 



Mean temperature of the soil at 9 a.m. . . . 46-8° 46-1° 46° 

 Highest „ „ „ „ ... 54° 51° 48° 



Lowest „ „ » » ... 42° 44° 45° 



Mean relative humidity of the air at 9 a.m. (complete saturation being 

 represented by 100), 79 per cent. 



Rain fell on 18 days, to the total depth of 2*15 in. (equivalent to about 

 10 gallons of water to the square yard). Heaviest fall on any day 0-41 in., on 

 the 29th. 



The prevailing winds vv^ere south-westerly. 



The average velocity of the wind was 9 miles an hour. 



There were 124 hours of bright sunshine, equal to 30 per cent, of the greatest 

 possible amount. 



There were 4 days on which no sunshine was recorded. 



May. — Throughout the opening days of the month the weather 

 was unsettled and breezy, but for some time the wind did not rise 

 to the force of a gale, and then it was only over the northern portion 

 of the kingdom that it became very strong. Its changeableness was, 

 however, a marked feature of the weather right through the m.onth, 

 and thunderstorms, with heavy rain and occasionaUy hail, were 

 not infrequent. The commencement of one of these stoiTQS, which 

 occurred over Surrey and south-east England on the 27th, was 

 accompanied by a sudden drop of 13° in temperature, and by hailstones 

 of phenomenal size. The earher days of the month were unusually 

 cool, the thermometer at Wisley faihng to rise so high as 60° for the 

 first ten days, whilst slight ground-frosts occurred on tw^o or three 

 nights ; but during the closing week both the days and nights were 

 unusually warni, the m_aximum on the 26th exceeding 80° at Wisley 

 and rising to nearly 80° daily from the 25th to the 30th. Generally 



