Dr Forry on the Climate of the United States. 231 



has been raised, seems by no means as yet decided; but 

 there is no doubt that the climate has become, as BufFon 

 would have said, ' less excessive.' " 



Contrary to Mr LyelFs opinion, one effect of clearing the 

 country is, doubtless, to distribute the temperature of the year 

 more unequally, thus rendering the seasons more variable ; 

 and hence causing, by the exposui-e of forests to spring frosts, 

 a serious inconvenience, which has been expei'ienced. both in 

 this country and in Europe. The reason of late and variable 

 springs, under these circumstances, may be explained by re- 

 ference to the fact, that, while the earth, clothed with forest 

 and covered with snow, is never frozen, and hence sprouts 

 forth its vegetation as soon as the snow is dissolved in spiking ; 

 the earth in an open country, on the other hand, requires, 

 after the snow is melted, to be thawed, thus rendering latent 

 for several weeks a great quantity of caloric. This affords 

 an explanation of the changes of climate referred to by Jef- 

 ferson, Rush, and Williams. If, indeed, the mean annual 

 temperature of Vermont has risen, according to Dr Williams, 

 10° or 12° within a century and a-half, it must surely have 

 had an intolerable climate, when our ancestors landed on the 

 rock of Plymouth ; and, upon the same principle of a general 

 increase of heat in our climate, the cultivation of the olive 

 and the fig, since the first settlement of our country, ought 

 to have advanced as far northward as Pennsylvania, if not 

 to Vermont itself ! 



Dr Webster devotes some ten pages in his first essay, to the 

 question of the cold of American winters ; and he arrives, from 

 a most extensive investigation of historical facts, at the con- 

 clusion, " that the winters have been from the first settle- 

 ment of America variable, now mild, now severe, just as they 

 are in the present age.'' A leading object with him is to shew 

 the errors of Dr Williams, who having maintained that the 

 mean temperature of Italy has increased 17°, wished to esta- 

 blish some analogous change in our own climate since its 

 occupation by Europeans ; and Dr Webster proves most con- 

 clusively, that " if Dr Williams is unfortunate in his facts, 

 he is still more so in his reasonings and deductions. 



As respects a supposed change of climate in the United 



