METEOROLOGICAL OBSERVATIONS MADE AT WISLEY, 59 



amount. Like its predecessor the month was colder than any corre- 

 sponding month for fifty years back, and both months afforded striking 

 contrasts to the warm and brilliant corresponding period of 191 1 

 So early as the 3rd there was a ground frost at Wisley sharp enough 

 to damage marrows and runner beans, but on the night of the 27th 

 there were eight degrees of frost and the dahlias were quite destroyed. 



The results from the observations made at Wisley are shown in 

 the following table : 



September. 



Mean temperature of the air in shade . 



. 52-6° 







Highest temperature of the air in shade 



. 66-o° 



on the 4th 



Lowest temperature of the air in shade 



• 32-5° 



on the 27th 



Lowest temperature on the grass 



. 23-6° 



on the 27th 



Number of nights of ground frost 



. 5 









At 



depth 



of 





1 ft. 



2 ft. 



4 ft. 



Mean temperature of the soil at 9 A.M. . 



55'3° 



55'8° 



56-8° 



Highest temperature of the soil at 9 a.m. 



597° 



59'3° 



58-6° 



Lowest temperature of the soil at 9 a.m. 



50'8° 



52-8° 



547° 



Mean relative humidity of the air at 9 A.M. (complete saturation 

 being represented by 100), 82%. 



Rain fell on 4 days, to the total depth of 2*99 inches (equivalent 

 to about 14 gallons of water to the square yard). Heaviest fall on 

 any day 1*58 inch, on the 29th. 



The prevailing winds were westerly from between south-west and 

 north. 



The average velocity of the wind was 5 miles an hour. 

 There were 124 hours of bright sunshine, equal to 33 per cent, of 

 the greatest possible amount. 



There were 3 days on which no sunshine was recorded. 



October. — This was another cool month, although relatively it was 

 less so than August and September had been. A temperature of 6o° 

 is a very moderate maximum for October, but even so at Wisley it was 

 reached only on six days in the course of the month, and on five other 

 days the thermometer failed to rise so high as 50 0 . The mean tempera- 

 ture was therefore low generally, and everywhere ground frosts were 

 frequent and occasionally severe ; in some Midland districts the thermo- 

 meter on the grass fell more than once to below 20 0 . It was, however, 

 a quiet month without strong winds, but with a good deal of fog, 

 especially in the early and late hours of the day. In the neighbourhood 

 of London and other large cities the fog interfered with the record of 

 bright sunshine, but over the country generally the number of hours 

 recorded was rather above the average, and this was especially the 

 case in the south-east of England. The first half of the month was 

 dry, very little rain falling until the 20th, but from that day to the 



