LOCAL CLIMATOLOGY. lO-j 



the United States. The same is to be said of the potatoes. And 

 it is a matter of doubt if any crop of cotton, rice, suirar-cane, or 

 other tropical production, can be made to yield so nuich wealth 

 to a comnumity extending over any considerable territory, as the 

 crop of grass and hay which flourish best where those tropical or 

 semi-tropical productions cannot be produced to advantage, if 

 at all. 



But for man himself, the bracing efl^ects of cool air are neces- 

 sary to the attainment of the highest forms of civilization. Warm 

 and moist are the conditions of vegetable perfection ; but cool 

 and dry are the best conditions for man's health and mental vigor. 

 Now, I doubt whether anywhere on the globe these contrary and 

 seemingly incompatible conditions are so well com])ined and 

 blended as in the northern and middle portions of the United 

 States, extending from the arid plains just east of the Rocky 

 mountains to the Atlantic coast. The winters are cool, if not 

 cold, and comparatively dry. The total amount of water-fall for 

 the months of December, January, February and March averages 

 scarcely one and a half inches ; and all through the summer, w'hile 

 the moisture is no more than is needed for veo^etation, the niirhts 

 are, for the most part, comparatively cool ; and seldom do more 

 than four or five days of heat, that can be regarded as at all op- 

 pressive even for us who are accustomed to a temperate zone, 

 occur in succession. Our position as the great wind-gap of the 

 northern hemisphere, to which I have so often referred, is largely 

 concerned in producing this result. The Rocky mountains leaving 

 the Cordilleras of Mexico, are not so situated as to shut oft", en- 

 tirely, or to any considerable extent, in the summer, the warm 

 breath of the return current and the moisture which it brings 

 from the Pacific ocean and the Gulf of Mexico ; while those moun- 

 tains are so situated as to give us invariably, even during the hot 

 season, within every few days, the cooling breezes from the north 

 — such as scarcely, if at all, ever visit the inhabitants of the old 

 world in our latitude, except, in fact, on the high lands of Central 

 Asia, where there is neither warmth nor moisture for an abundant 

 vegetation. 



What these influences are to be on man's ph3'sical condition and 

 development, can be, at present perhaps, only a matter of conjec- 

 ture and prediction. But they augur well ; they predict a glo- 

 rious future — a coming civilization such as the world has never 



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