Dr. Forry on the Climate of the United States, ^"c. 233 



is deemed supererogatory. The phenomena observed by Yolney 

 are truly facts ; but the causes being unknown, the theory in re- 

 gard to the difference of temperature east and west of the Alle- 

 ghanies, was naturally suggested. Instead of deducing general 

 laws from universal facts, this theory of Yolney and Jefferson was, 

 as will be seen, a premature deduction — the result of hasty and 

 partial generalization. 



M. Volney also presents an extended investigation of the sys- 

 tem of winds in the United States ; and the ignorance of this cel- 

 ebrated traveller in thus attempting to explain the meteorological 

 phenomena peculiar to the region of the great lakes, shows how 

 little was known forty-five years ago of the laws of meteorology. 

 In reference to the Trans-AUeghany region, he thus remarks : — 

 "I think I have clearly demonstrated that the southwest wind of 

 the United States is nothing but the trade-wind of the tropics 

 turned out of its direction and modified, and that consequently 

 the air of the Western country is the same as that of the Gulf of 

 Mexico, and previously of the West Indies, conveyed to Ken- 

 tucky. From this datum flows a natural and simple solution of 

 the problem, whiclf at first must have appeared perplexing, rvhij 

 the temperature of the Western country is hotter by 3° of latitude 

 than that of the Atlantic coast, though only separated from it by 

 the Alleghany mountains. The reasons of this are so palpable that 

 it would only be wearying the reader to give them. Another 

 consequence of this datum is, that the southwest winds being 

 the cause of a higher temperature, it will extend the sphere of 

 this temperature so much the farther, the greater the facility with 

 which it can prevade the country; and this aflTords a very favor- 

 able presage for the parts that lie in its way, and are exposed to 

 its influence, namely those in the vicinity of Lakes Erie and On- 

 tario, and even all the basin of the river St. Lawrence, into which 

 the southwest wind penetrates." 



Now these are the opinions still maintained at the present day, 

 to account for the supposed fact of the higher temperature of our 

 tramontane region. It is a good rule in philosophy to ascertain 

 the truth of a fact before attempting its explanation, — a truism, 

 the observance of which would have saved M. Volney the labor 

 of constructing his complex theory of the winds. All thermo- 

 metrical results confirm the law, that in proportion as we recede 

 from the ocean or inland seas, the climate grows more excessive ; 



