226 Dr. Forry on the Climate of the United States, iS^'c. 



principle that any alteration in the climate of a locality supposes 

 a corresponding alteration in its physical features. That there 

 ate poles of greatest cold corresponding to the terrestrial magnetic 

 poles, as distinguished from the poles of rotation, is, however, 

 quite probable. 



Does the climate of a locality, in a series of years, undergo any 

 permanent changes 7 The question has been much debated, 

 whether the temperature of the crust of the earth or of the in- 

 cumbent atmosphere, has undergone any perceptible changes 

 since the earliest records, either from the efforts of man in clear- 

 ing away forests, draining marshes, and cultivating the ground, 

 or from other causes. So general is the opinion that the tem- 

 perature of the winter season in northern latitudes has become 

 higher in modern than it was in ancient times, that it has been 

 regarded as an admitted fact. Among the writers of reputation 

 who have adopted and maintained this opinion, are the Abbe Du 

 Bos, Buffon, Hume, Gibbon, Volney ,• and, in our own country, 

 Jefferson, Williams, and Dr. Holyoke. By them it is alleged that 

 the winters of the south of Europe, in the time of the first Ro- 

 man emperors, were, according to the concurring testimony of 

 many authors, much more severe than now. In proof of this 

 assertion, they quote many passages from the ancient authors — 

 Juvenal, Virgil, Ovid, etc. ; and in regard to Gaul and Germany, 

 the writings of Caesar, Diodorus Siculus, etc. 



Gibbon, in his "Decline and Fall of the Roman Empire," has 

 contributed perhaps more than any other to perpetuate the affirm- 

 ative of this opinion. The ignorance of the great laws of climate 

 betrayed by him in the observation, that " Canada, at this day, 

 is an exact picture of ancient Germany,''^ finds an excuse in the 

 fact that he lived before the epoch of Baron Humboldt ; but it is 

 truly surprising that Malte Brun should, many years after, make 

 the same comparison. Gibbon's reputation is that of a historian ; 

 but it is easy to show, as we have done elsewhere, that he falls 

 short even in this character, as regards the assertion, when speak- 

 ing of transporting heavy waggons over the frozen rivers of an- 

 cient Germany, that ^'modern ages have not presented an in- 

 stance of a like phenome7ion.'' 



As the full discussion of this question alone would take up the 

 space allotted to this article, the most general view of it must 

 here suffice. For several years past, we have devoted much at- 



