

Dr. Forty on the Climate of the United States, fyc. 235 



atmosphere. On these causes depend in a great degree, those 

 contrasts of vegetable life observed in islands, in the interior of 

 continents, in plains, and on the summits of mountains. As the 

 region of the great lakes does not exhibit a greater contrast in the 

 opposite seasons than that of Philadelphia, it follows that plants 

 which, from not being adapted to extremes of temperature, cannot 

 endure the severe winter of Albany, will nourish in the more equal- 

 ized climate of the same latitude on the ocean or the great lakes. 

 Thus, as Volney and JefTerson saw that the vegetation of Phil- 

 adelphia is found in the modified climate of our northern lakes, 

 while similar plants will not flourish on the same parallels in the 



I the interior of New York, Vermont, and New Hampshire, the the- 

 ory in regard to the difference of temperature, east and west of 

 the Alleghanies, was naturally suggested. If, however, these 

 philosophers had chanced to observe the vegetation, by way of 

 comparison, along the coast of Rhode Island or Connecticut, and 

 °n the same parallel in Illinois or farther westward, instead of 

 comparing the region of the lakes and Albany, the world would, 

 °f course, have been edified with the opposite theory, viz. that 

 t»e climate east of the Alleghanies is milder by 3° of latitude 

 wan that west. While at Fort Trumbull, Connecticut, the mean 

 JJJter temperature is 39°-33, at Council Bluffs it is as low as 

 ' 4 ' • Hence plants sensible to a low temperature, which flour- 

 l5{ im the climate of the former, will perish in the latter ; for while 

 e ttean temperature of the coldest month at Fort Trumbull is 

 only 34°-50, at Council Bluffs it is 22°61. This is also demon- 

 rated by the average annual minimum temperature, that of the 

 ormer being 9°, and that of the latter -16°; and equally so by 

 e minimum temperature of the winter months, that of Decem- 

 *j January, and February being at Fort Trumbull respectively 

 ,p > 10°, and 16°, and at Council Bluffs -4°, - 13°, and -11°. 

 n tiie other hand, it will be found that the vegetables which 

 n e ndure the rigorous climate of Council Bluffs, will flourish more 

 gorously than in the region of Connecticut ; for at the former, 

 e v ernal increase is 27°-47, and at the latter only 1 i°-67. More- 

 ^ r ) the latter increase is added to a winter temperature of 39°33 ; 



• e tJle former, added to 24°-47, more than doubles itself, the 



|^ence of which 



een already pointed out. These relations, as developed in 

 e tabular abstracts appended to the author's work on ' : The Cli- 



upon 



vegetation 



