CLIMATE. 



81 



ground being covered with trees is not the sole cause. 

 Neither can the extensive mountains of North Ame- 

 rica produce the effect, for other countries have 

 mountains equally extensive, and even higher, and 

 are, nevertheless, noted for their mild temperature, 

 as in Switzerland, and in the vicinity of the Pyre- 

 nees. The great lakes in North America have also 

 been supposed to contribute to the coldness of the 

 country, and particularly to the keenness of the 

 north-west wind, but this also is an error ; for all the 

 great lakes lie westward of the north-west, and some 

 of them to the southward of the west : and did they 

 even lie in the direction of the north-west wind, they 

 could not increase the cold, because they do not 

 freeze, except near the edges, and large bodies of 

 water we know would rather tend to increase, 

 than lessen, the temperature of the air. Such in- 

 deed is the fact, for it has already been mentioned, 

 that the climate"^ on the western sides of the Alleg- 

 hanies, and particularly near the lakes, is much 

 milder than that of the country on the eastern side 

 of the mountains. 



Dr. Barnwell* has lately attempted to account for 

 the circumstance, upon principles altogether new: 

 viz. the prevalent winds, current of the ocean, and 

 the gulf stream : he shows, by a course of laborious 

 reasoning, how these currents are influenced by the 

 winds; how, in their turn, they re-act upon the air 

 and thus affect the temperature of the adjacent 

 land. 



Physical Investigation, Philad. 1802^ Svo, 



