108 IV. CLIMATE. 



be resorted to, by deducing from the means of extremes 

 or from observations made at fixed hours. 



Dividing the year into seasons of three months each, 

 and regarding December, January, and February as the 

 three winter months, comparisons may be instituted be- 

 tween the means for the seasons and that for the whole 

 year at the same j)lace, or the seasons at different places 

 may be compared together. In making such compari- 

 sons for places in Britain, it will usually be found that 

 the mean for the three autumnal months comes nearest to 

 the mean for the whole year ; the difference in several 

 recorded instances being less than a single degree on 

 Fahrenheit's scale. In very few instances are the means 

 for autumn so much as two degrees higher ; and perhaps 

 in no correct record are they a full degree under. This 

 near approach to equality seems to hold true alike, 

 whether the mean is deduced from the daily extremes or 

 from registers at stated hours. — The mean for the three 

 spring months is everywhere somewhat lower than that 

 for the whole year ; usually between one and two degrees 

 lower ; seldom slightly more than two degrees. — The 

 mean for the three winter months is frequently about ten 

 degrees lower than that for the whole year ; this dif- 

 ference rising to eleven or twelve degrees for some places 

 in the south-eastern provinces of England, and sinking to 

 nine or even less on the south-western coasts. — The mean 

 for the three summer months, through great part of the 

 island, may be regarded as about ten degrees higher than 

 that for the whole year ; the difference increasing to 

 eleven or twelve degrees in the south-eastern provinces, 

 and decreasing to eight degrees or thereabouts in the 

 extreme south-west, as at Penzance, in Cornwall. 



Leaving out of view the months of spring and autumn, 

 and making a direct comparison between those of summer 



