THE CLIMATE OF THE LAKE REGION. 223 



fluence of Lake Superior, it loops west again, passing 

 south of Marquette and Ontonagon to Bayfield and Du- 

 luth, whence, bending east a second time, it passes near 

 Beaver Bay in Minnesota, and crossing Keweenaw Point 

 emerges upon Canadian soil some forty miles to the north 

 of Sault Ste. Marie. The loop which opens westward de- 

 notes the position of a zone of cold located along the 

 elevated district which forms the water-shed between Lake 

 Superior and the Mississippi. The axis of this zone, in- 

 stead of lying along the head -waters of the streams flow- 

 ing north and south, is crowded southward, apparently, by 

 the influence of Lake Superior. The other loop, which 

 opens eastward, is a zone of warmth stretching along the 

 south shore of Lake Superior from Ontonagon to the 

 Sault Ste. Marie. An island of cold seems to be located 

 in the southern portion of the lower peninsula of Michi- 

 gan, and another in northern Iowa. An area of uniform 

 temperature stretches across middle Ohio, as we have al- 

 ready seen to be the case also in July. 



There is a method of obtaining a still more precise, 

 and therefore more correct, expression of the distinctive 

 characteristics of the climate of the lake region. Aver- 

 ages of months and seasons suffice, indeed, to indicate the 

 length of the growing period and the average severity of 

 the winter. But there is another aspect of climate which 

 possesses at least equal importance ; though in climatic 

 discussions it has been largely overlooked. Published 

 tables give us means of the year and of the several sea- 

 sons, and their authors seem to think that in this they 

 have brought to view all the important elements of cli- 

 mate which bear on health and production of crops. A 

 little reflection, however, shows that the extremes of climate 



