MICHIGAIi STATE POMOLOGICAL SOCIETY. 



487 



heat enough, when converted into mechanical power, to elevate 

 a weight of 1,390 pounds one foot. Now, in giving this great 

 amount of heat, what an immense influence a large body of 

 water must exert on the adjoining atmosphere! The heat of 

 the summer is stored up in the lake, and given out again in 

 the winter. Hence the absence of extremes. The summer of 

 the lake shore can never reach that scorching heat of the 

 inland summer, nor its winters the destructive cold of the 

 inland winter. Territories hundreds of miles south of us may 

 grow fruits that our summers cannot ripen; but at the same 

 time our evergreens are wholly unknown to them, — they, could 

 not endure the extremes of their winters. Let me illustrate 

 this great principle by aid of a rude chart of our State : 





"7 '^ 



NoTB. — It la desired that these lines be regarded not as absolute curves of tempera- 

 tnre, but simply as illustrations of the general influence of lake bodies upon our 

 climatology. 



Let this line (a) represent the isotherm of our summer, — 

 say 71°. It comes upon ns from the westward, from latitudes 



