IV. CLIMATE. 109 



and winter, the mean difference for sixteen places in 

 South Britain (excluding Cornwall) is very sliglitly under 

 23 degrees ; — that deduced from the registers for twenty 

 places in Mid Britain amounts to 20.20 degrees; — -for 

 nine places in the East Highlands it is 21.26 degrees ; — 

 for the North Isles and north coast of Scotland it 

 becomes 15, on the average of four places. At Penzance, 

 near the extremity of the Peninsula province, the dif- 

 ference between the summer and winter means is repre- 

 sented to be only 16.18 (16.68?); and for four other 

 places in Cornwall it is 17. At Plymouth, in the same 

 province, it is still only 16, on the means from the hourly 

 observations during 5 years. It would appear by these 

 various figures, that through the greater part of Britain, 

 subject of course to deviations from local conditions, the 

 difference between the mean temperatures of summer and 

 winter is from 20 to 21 degrees of Fahrenheit's scale. 

 Further, it may be said that the difference is increased to 

 23 degrees in the south and south-east of England, where 

 it is greatest; and decreased also to 16 or 17 degrees in 

 the extreme south-west, where it is slightest ; possibly 

 with an exception for the North Isles, at only 15. Mea- 

 sm'ed by the centigrade scale, this may be called a dif- 

 ference of llg- degrees for Britain generally ; rising to 

 about 13 degrees in the south-east of England ; and 

 sinking to 9 degrees for the extreme south-west. It has 

 been also stated below 8 degrees for Unst, in Shetland, a 

 very insular position at the extreme north of Britain. 



How closely these differences will correspond with 

 those of places at considerable altitudes, it is not yet 

 possible to determine. From the registers at Lead-hills, 

 in South Scotland, at an altitude of 1280 feet, it would 

 seem that the difference between the summer and winter 

 means there nearly equals what has been noted in the 

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