224 J. HOPKINSON" — THE CLIMATE OF WATFOED.' 



and the average annual deviation from the mean is 0°"75, the 

 temperature being below the mean for four years and above it 

 for six years. 



The coldest year (1879) was the wettest, had the smallest mean 

 daily range of temperature, more than the average amount of cloud, 

 the smallest number of days of clear sky, and the largest number 

 of days of overcast sky; the warmest year (1884) was the driest, 

 had the largest mean daily range of temperature, less than the 

 average amount of cloud, nearly the largest number of days of 

 clear sky, and the smallest number of days of overcast sky. 



The extreme range of temperature was 85°'3, the absolute 

 minimum being 6°'4 on 21st Januaiy, 1881, and the absolute 

 maximum 91°'7 on 5th July, 1881, the range thus being the 

 same for this year as for the whole period. 



The mean daily range of temperature, 14°-4, varied from 13°1 

 in 1879 to 15°-2 in 1884. 



Autumn is warmer than spring, by 2° -6, chiefly owing to the 

 colder nights in spring. On the other hand the excess of the 

 temperature of summer over that of winter, 21°"9, is more due 

 to the warm days in summer than to the cold nights in winter. 

 Spring is 8°'2 warmer than winter, and summer 13°'7 warmer 

 than spring; autumn is 11°-1 colder than summer, and winter 

 10°-8 colder than autumn. Thus winter passes slowly into 

 spring, and spring quickly into summer, while summer passes 

 into autumn, and autumn into winter, at a nearly equal rate. 



The mean daily range of temperature is greatest in summer and 

 least in winter, and greater in spring than in autumn ; but the 

 absolute range has been greatest in autumn and least in winter, 

 and greater in spring than in summer. Although the nights 

 are as a rule colder in spring than in autumn, a colder night 

 has occurred in autumn than in spring. In winter the nights 

 are not so much colder than in spring as are the days ; in 

 summer they are not so much warmer than in autumn as are 

 the days. 



January is on the average the coldest month, and July the 

 warmest, though only 0°-l warmer than August. The tempera- 

 ture increases from January to July, and decreases from July to 

 January as follows : — 



Increase. ^ Decrease. ^ 



•2 

 ■4 



Jan. to J'eb. 3 



Feb. to March 1 



March to April 4 



April to May 5 



May to June 6 



June to July 2 



•7 



Assuming that the mean temperature of each month occurs 

 about the middle of the month, it would appear that the in- 

 crease of temperature is most rapid during the month of May, 

 or from the middle of April to the middle of June ; and that 

 the decrease is most rapid during the month of October, or 

 from the middle of September to the middle of November. 



