THE CLIMATE OF THE LAKE REGION. 221 



mild as that of Cincinnati. Traverse City corresponds, in 

 this respect, with Omaha, Muscatine, Ottawa and Aurora. 

 Mackinac and Marquette compare with Green Bay, Fort 

 AVinnebago and Prairie du Chien. The isotherm of 22 

 is deflected by the influence of Lake Michigan over a 

 belt of four and a half degrees. This is more than 300 

 miles in a straight line, and is equal to the distance from 

 Mackinac to Fort Wayn. 



Another fact strikingly exhibited is the difference be- 

 tween the January temperatures along the opposite sides 

 of Lake Michigan. The mean at Chicago is 22^, while 

 that of New Buffalo, directly opposite, is 30. The mean 

 of Milwaukee is 20^, while that of its vis-a-vis, Grand 

 Haven, is 25. The mean of Green Bay is 19, and that 

 of Appleton 15^, while that of Traverse City is 22. 

 Greatly as the January climate along the western shore 

 is ameliorated by the influence of the lake, that along the 

 eastern shore is still further ameliorated to the extent 

 of four to seven degrees.' This contrast results from the 

 prevailing direction of the cold winds, which, in the North- 

 western States, is from the west and southwest. The re- 

 sults of observations made in January have already been 

 given. These results embody all January winds except 

 those directly from the north or south. 



At the same time the January climate along the east- 

 ern .border of the peninsula of Michigan is not much 

 more severe than that along the western, though the 

 prevailing winds along the eastern shore, as in Wisconsin 

 and Illinois, are from the west of the meridian, and 

 carry the influence of Lake Huron away from the land. 

 This state of things is accounted for by three considera- 

 tions. First, the influence of Lake Michigan is distinctly 



