118 Tlie Climate of Great Britain. 



part, in Fig*. 1 could be completed, they would be found to 

 form two ovals. The American oval would enclose the Ameri- 

 can pole of mean temperature, but very eccentrically, showing 

 that the pole of extreme winter temperature lay westwards and 

 southwards, probably near Victoria Land. The Asiatic oval 

 would not probably enclose the Asiatic pole of mean tempera- 

 ture ; and the position indicated for the Asiatic pole of extreme 

 winter cold lies on or near the Arctic circle, where it is crossed 

 by the river Lena. At the true pole of the earth the extreme 

 winter cold is probably not nearly so intense as the cold at 

 either of the points here indicated. 



From the direction of the isochimenal through London, it 

 is evident that the Eastern Counties and Kent experience the 

 coldest winters of all places in the British Isles, while Cornwall 

 and the south-westerly parts of Ireland enjoy the mildest winter 

 climates. In fact, winter in Cornwall is not more severe than 

 in Constantinople ; and in south-west Ireland the winter is 

 still milder, approaching, in this respect, to the winter climate 

 of Teheran. 



The contrast, when we turn to the isotheral of London, is 

 remarkable. Instead of travelling nearly northwards, this 

 curve passes in a south-westerly direction, reaching its greatest 

 southerly range in the central part of the Atlantic Ocean; 

 thence it travels with a northerly sweep through Nova Scotia 

 and Canada, till it reaches its greatest northerly range near 

 the Eocky Mountains.* Thence it turns sharply southwards, 

 crosses Vancouver's Island, sweeps nearly to latitude 45° in the 

 central part of the Pacific, whence passing slightly northwards 

 it crosses the southern part of Saghalien Island. Here it turns 

 sharply northwards, crosses that very district of Siberia which, 

 in Fig. 1, is occupied by the isochimenal of intensest winter 

 cold, traverses Siberia, and passes near St. Petersburg, through 

 Berlin and Amsterdam to London. 



The relations thus presented by the isotheral of London are 

 precisely the reverse of those exhibited by the isochimenal. The 

 isotheral forms a closed, irregular oval, whose greatest length 

 lies on the two oceans. Here it falls outside the line of mean 

 annual heat, while on the continent it falls far within this line. 



In another respect the isotheral presents' a noteworthy 

 contrast to the isochimenal. While the latter encloses an area 

 largely exceeding the area enclosed by the mean annual line, 

 the isotheral encloses an area noticeably smaller. t 



* It is noteworthy that the minimum distance of the isotheral from the North 

 Pole here atinined, is exactly equal to the iniuinmm distance of the isochimenal 

 from the equator. 



f Here hd important advantage of the isographic projection is exhibited. The 

 relation pointed out is altogether obliterated in Mt-rcator's projection, and could 

 only be roughly inferred from any but an isographic projection. 



