THE CLIMATE OF THE LAKE REGION. 209 



through all the places which have the same winter tem- 

 perature as that city, we should find that in receding 

 from the coast it would gradually deflect southward. 

 Toward the center of the continent the amount of the 

 deflection would be considerable; but in approaching the 

 Pacific coast we should observe a very remarkable deflec- 

 tion toward the north. In the elevated regions of the 

 Allegheny and Rocky mountains would, indeed, interpose 

 the disturbing effects of increased altitude, so that our 

 isothermal line would be abruptly deflected southward in 

 passing both these mountainous belts, but would turn 

 northward again to its normal position after passing 

 them. The winter isothermal of 30 passes through New 

 Haven in latitude 41 18'. In Kansas this isothermal is 

 as far south as Fort Riley (39), whence it bends north- 

 ward to beyond the latitude of Fort Laramie (42 40'). 

 Experiencing there a sudden southward flexure to Santa 

 Fe (35 30') in crossing the Rocky Mountains, it then 

 resumes its northward trend upon the Pacific slope, and 

 reaches the Pacific shore only within the limits of Alaska. 



The climatic influences of vast bodies of salt water, like 

 the Atlantic and Pacific oceans, have long been under- 

 stood. The effect of small inland bodies of fresh water 

 in averting early autumnal frosts has also been gener- 

 ally remarked. But, as before intimated, meteorologists 

 do not seem to have observed till recently that great 

 lakes, like Lake Michigan and Lake Superior, exert an 

 influence in deflecting the isothermal lines which is quite 

 comparable with that exerted by the great oceans them- 

 selves. 



These lakes, in truth, are no inconsiderable representa- 

 tives of the ocean. Lake Superior is 460 miles long and 

 14 



