80 



UNITED STATES. 



that from the 4th of August to the 4th of September, 

 the thermometer in various places beyond lake St, 

 Clair never was higher at noon than sixteen and an 

 half degrees of Reaumur (69 Fah.), and that in the 

 Kiorning and evening it frequently sunk to five and 

 an half (44 5-10 Fah.), which is colder than at Mon- 

 treal under the same parallel. 



These facts accord perfectly with the general 

 results, lately published by Mr. Alexander Mac- 

 kenzie, in his interesting account of his travels in 

 the west and north-west parts of America ; and by 

 Robson and Umfreville* at Hudson's bay. 



Mr. Volney has taken great pains to prove the 

 difference between the temperature in the Atlantic 

 eoast, and that of corresponding latitudes in Europe: 

 and, though it has been already shown, that some of 

 his thermometrical statements are not founded on au- 

 thority, and although others of them will not apply at 

 present, owing to a change in the climate, yet the fact 

 is, nevertheless, true; and as he has not to account 

 for it, the investigation of the subject shall now be 

 attempt eel. 



The first cause contributing to the great degree of 

 cold in the United States, is, without doubt, the ex- 

 tent of our forests. The eiT*:.'Ct of clearing a country 

 to render it less cold, was first ably pointed out by 

 our countryman Dr. Williamson, in a paper express- 

 ly written to explain the cause why the Winter's 

 cold and Summer's heat, in the United States, are 

 less violent than formerly, t But it is clear that the 



* Present State of Hudson's Bay, 1790." 

 t I'rans. Amer. Phil, Sec. vol. 



