METEOROLOGICAL OBSERVATIONS MADE AT WISLEY. 53 



abnormally cloudy, with a general deficiency of bright sunshine, but 

 at the same time a shortage of rain over the greater part of the Kingdom 

 and especially over the south-eastern and eastern counties of England. 

 Although there were not many really hot days the mean temperature 

 for the month was again higher than the average ; the highest point 

 reached by the thermometer at Wisley was 77 degrees, on the nth, 

 and there were several nights when the thermometer on the grass fell 

 dangerously low for vegetation — 10 degrees of frost were registered at 

 Wisley on the night of the 1st, and 5 degrees on the nights of the 25th 



N. 



S. 



Fig. 20. — Distribution of Winds during the Year. The 

 relative Frequency of Calm is shown by the Shaded 

 Circle in the Centre. 



and 26th, the tips of bracken becoming blackened by the frost on the 

 last-named dates. But as a rule cloudy skies again served to maintain 

 the night temperatures at a fairly high level and thus kept up the mean 

 for the month — the thirteenth in succession warmer than the average ; 

 and it is worth noting that the records at Greenwich Observatory fail to 

 show such a long succession of relatively warm months in any former 

 period. Thunderstorms occurred at Wisley on the 12th and 17th, 

 but on the last day of the month one of unusual seventy occurred 

 in the neighbourhood of Peterborough. Preceded by a remarkable 

 darkness, it was accompanied by hail and torrential rain. ' After 

 the storm . . . the country was inundated ; not merely roads, 

 but hundreds of acres of arable and grass land being under water. 

 Two hours afterwards the hail lay thick on the banks as though a 

 snowstorm had passed.' 



