142 HEAT OF LOWEST STRATUM OF AIR. 



runs rapidly southwards, following the course of 

 the northern Rocky Mountains, touching Lake 

 Winnipeg (Cumberland House Factory 0°), 

 and cuts the southernmost sweep of Hudson's 

 Bay. From the eastern coast of Labrador it 

 stretches northwards again, and without reaching 

 the southern point of Greenland (Julianshaab, 

 0°'9) returns to Iceland. 



If you follow the course of these lines of tem- 

 perature with your eye on a map of the World, you 

 will remark, that the belt of land enclosed between 

 the isotherms of 20° and 0° (68° and 38° Fahr.), 

 the true temperate zone of the northern hemi- 

 sphere, bends farthest towards the north in 

 Europe, and here also has its greatest breadth, 

 since it contains not only the European continent, 

 but also all the islands lying between the parallels 

 of 35° and 71° N. L., and even a part of the 

 north coast of Africa, a breadth altogether of 36° 

 of latitude. However, at the extreme east of 

 Europe, and much more strikingly in Asia, its 

 limits are contracted, and it shrinks at its nar- 

 rowest measurement in the interior of Asia to 

 a breadth of 20° of latitude. At the west coast 

 of North America, it encloses so much as lies 

 between 28°, and perhaps 66° N. L. of the small 

 strip of coast land, formed by the western declivity 

 of the high mountains which run nearly parallel 

 with the sea coast, but towards the interior it soon 



