28 Dr. Forry on the Climate of the United States, S^c. 



lowing posts, which are all nearly on the same parallel of 4P 30', 

 the first two being on the ocean, and the last two far in the inte- 

 rior, remote from large bodies of water, may be adduced as strik- 

 ing examples : 



Highest. Lowest. Mean annual range. 



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



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



Council Bluffs, near the conflu- > m^ i^ ion 



r ni ./ ] TV/I- r- 104 . — 16 . . 1/iO 



ence oi Flatte and Missouri, 5 



Fort Armstrong, Rock Island, III., 96 .—10 . .106 



These results, it may be necessary to add, axhibit the average 

 range of a series of years. The extreme range, for example, at 

 Fort Brady, during 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 Craw- 

 ford 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 mercury there 

 seldom rises as high as in our northern regions. 



Hence it follows that latitude alone constitutes a very uncertain 

 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 thq,seasons 

 may be extraordinarily unequal. So much, indeed, may the 

 phenomena of superficial terrestrial temperature, as depending on 

 the position of the sun, be modified by local causes, that a classi- 

 fication 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 third class of the same division 

 are very dissimilar. In the cUmate of the third class of posts, dis- 



