Dr. Forry on the Climate of the United States, ^'c. 27 



at Fort Brady to be 18°-42, while at Hancock Barracks it is 

 24°-49; at Fort Sullivan it is 17°- 16, while at Forts Snelling 

 and Howard, it is respectively 30°-83 and 24°- 10, the latter being 

 partially modified by Green Bay ; at Forts Preble, Niagara, and 

 Constitution, and the city of Salem, the ratios are 18° -42, 16° -77, 

 16°-83 and 17°-89, and at Fort Crawford, on the other hand, it 

 is 25°-83 ; and lastly at Forts Wolcott and Trumbull, it is 14°-71 

 and ll°-67, while at Council Bluffs, Fort Armstrong, and West 

 Point, it is respectively 27°-47, 23°-99 and 18°-82. Fort Colum- 

 bus, as in the preceding comparisons, stands as an exception, its 

 ratio, notwithstanding it is lower than any one in the opposite 

 class, being the highest in its own, with the exception of two 

 posts. The peculiarity in the increase of the temperature of 

 spring, as manifested in the vegetable kingdom, constitutes a fea- 

 ture which strongly characterizes excessive climates ; for, as 

 Baron Humboldt remarks, " a summer of utn'form heat excites less 

 the force of vegetation, than a great heat preceded by a cold sea- 

 son." Accordingly we find that in these excessive climates, (un- 

 like the uniform ones on the ocean and lakes, in which the air is 

 moist and the changes of the seasons slow and uncertain,) summer 

 succeeds winter so rapidly that there is scarcely any spring, and 

 vernal vegetation is developed with remarkable suddenness. At 

 Fort Vancouver, the difference between the mean temperature of 

 winter and spring is only 6°-67, which is about one third of the 

 difference observed at the posts in our modified climates on the 

 same parallel, and little more than one fifth of the difference ex- 

 hibited in the excessive climate of Fort Snelling. 



Another feature which characterizes these two systems of cli- 

 mate remains to be considered, viz. the mean annual range of 

 the thermometer. Comparing the posts on the same parallel, the 

 following relations are found : — At Fort Brady, on the one hand, 

 the range is 110°, and at Hancock Barracks, on the other, it is 

 118°; at Fort Sulhvan it is 104°, while at Forts Snelling and 

 Howard, it is 119° and 123° ; at Forts Preble, Niagara and Con- 

 stitution, it is respectively 99°, 92° and 97°, while at Fort Craw- 

 ford, on the same parallel, it is 120° ; and lastly at Forts Wolcott 

 and Trumbull, it is 83° and 78°, while at Council Bluffs, Fort 

 Armstrong and West Point, it is 120°, 106°, and 91°. Fort Co- 

 lumbus, as before, presents an exception. In further elucidation 

 of the law regulating the extremes of temperature, the four fol- 



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