80 Dr Forry on the Climate of the United States. 



Highest. Lowest. Mean annual range. 



Fort Wolcott, Newport, R. I., 85 . 2 . . 83 



Fort Trumbull, New London, Ct., 87 . 9 . . 78 



Council BlufFs, near tlie conflu- 1 -.aj^ -,/> -tnr, 



ence of Platte and Missouri, / ^^^ * ~~^^ ' ' -^"^ 



Fort Armstrong-, Rock Island, 111., 9G . —10 . . 106 



These results, it may be necessary to add, exhibit the 

 average range of a sei"ies of years, The extreme range, for 

 example, at Fort Brady, dm'ing a period of eleven years (from 

 1820 to 1830 inclusive), is 130°, the mercury sinking in 1826 

 as low as — 37°, and rising in 1830 to 93° Fahr. At Fort 

 Snelling in 1821, the mercury sunk to — 32°, and in 1827 

 rose to 96°, being a range of 128°. At Fort Howard, in 

 1823, it rose to 100°, and sunk to — 38° ; being a range in the 

 same year of 138°. At Fort Crawford we find the mercury 

 in 1820 noted as high as 99°, and in 1821 as low as —36°, 

 being a range of 135° ; at Fort Armstrong, in 1821, as low 

 as— 28°, and in 1830 as high as 98°, being a range of 126° ; 

 and lastly, at Council Bluffs as low, in 1820, as — 22°, and in 

 1822 as high as 108°, being an extreme range of 130°. At 

 the last named post, the thermometer rose every year above 

 100°. When the Southern division of the United States 

 comes under investigation, it will be seen that the mer- 

 cury there seldom rises as high as in our northern I'egions. 



Hence it follows that latitude alone constitutes a very un- 

 certain index of the character of climate ; for although two 

 places may have the same mean annual temperature, and 

 thus be on the same isothermal line, yet the distribution of 

 heat among the seasons may be extraordinarily unequal. 

 So much, indeed, may the phenomena of superficial terres- 

 trial temperature, as depending on the position of the sun, 

 be modified by local causes, that a classification of climates, 

 or a system of medical geography, having for its basis mere 

 latitude, is wholly inadmissible. 



It is thus seen that the climatic features of the coast of 

 New England and of the region of the great lakes, exhibit a 

 striking resemblance, while those of the thii'd class of the same 

 division are very dissimilar. In the climate of the third class 

 of posts, distinguished by great extremes of temperature, by 



