224 Dr Forry on the Climate of the United States. 



The tropical current or trade wind, it is said, deflected by 

 the Mexican elevations, enters the great basin of the Missis- 

 sippi, and sweeps over an extensive country lying east of the 

 Rocky Mountains ; and that when this current continues for 

 some days, such extraordinary heat prevails, even through 

 the basin of the St Lawrence, that the thermometer at 

 Montreal sometimes rises to 98° Fahr. In winter, on the 

 contrary, when the locality of this great current is changed 

 to more southern latitudes, succeeded by the cold winds 

 which sweep across the continent from the Rocky Mountains, 

 or descend from high latitudes, this region becomes subject 

 to all the rigours of a Siberian winter. 



Upon the fallacy of these views, it is deemed unnecessary 

 to dilate. It is proved by thermometrical data, that the 

 climate west of the Alleghany is more excessive than that 

 on the Atlantic side, a condition that would seem unfriendly 

 to the migration of plants. Thus, Jefferson Barracks, on the 

 Mississippi, exhibits a gi'eater contrast in the seasons than 

 "Washington City ; and the same is true in regard to Fort- 

 Gibson and Fort-Monroe, notwithstanding the former is 1° 

 32 farther south. That the climate of the Peninsula of 

 Michigan, encompassed by ocean lakes, should prove genial 

 to plants that will not flourish in the same latitudes in 

 the interior of New York, is indeed, consonant with the 

 laws of nature ; and that the same plants should flourish 3" 

 farther north in the Valley of the Mississippi than on the 

 eastern side of the mountain, finds a sufiicient explanation in 

 the following extract from Murray's Encyclopaedia of Geo- 

 graphy : " Powerful summer heats are capable of causing 

 trees and shrubs to endure the most trying eff'ects of cold in 

 the ensuing winter, as we find in innumerable instances, and 

 vice versa. Hence, in Great Britain, so many vegetables, 

 fruit-trees in particular, for want of a sufficiently powerful 

 sun in summer, are affected by our comparatively moderate 

 frosts in winter ; while upon continents, in the same degree 

 of latitude, the same tree arrives at the highest degree of 

 perfection." 



As the writer has found the opinions of M. Volney, as well 

 as those of Jeff"erson, Williams, and Rush, q^uoted as oracular 



