Changes of Timber and Plants^ ^c. 301 



Philadelphia April Isty 1808. 

 Dear Sir, 



That nature delights in, and actually effects, 

 entire changes and successions in the vegetable pro- 

 ductions of the earth, (I mean circumscribed spots of 

 earth) is a Jact which appears to have been familiar 

 to the observing part of mankind, as long ago as the 

 age of Pliny the elder. I believe, but of this I am 

 not certain, that the same thing is noticed in the wri- 

 tings of Aristotle, and is even brought forward by 

 that Avonderful man, as an argument in favour of the 

 doctrine of equivocal generation. Be this, however, 

 as it may, the fact does not need the authority of any 

 of the illustrious writers of either ancient or modern 

 times, for its permanent establishment. It is already 

 established by nature herself, whose authority is para- 

 mount to every thing else, and must, in the present 

 instance, be regarded as final and conclusive. The 

 only thing extraordinary in the case is, that at this en- 

 lightened period, any one, who has an opportunity of 

 observing for himself, should entertain doubts of so 

 obvious a truth. I presume it is purely for want of 

 such an opportunity, that the Edinburgh Reviewers 

 have taken exception at the narrative of Mackenzie. 

 For these writers appear by no means ignorant of facts 

 and subjects that lie within the sphere, of their own 

 observation. 



Our own country is unquestionably one of the most 

 favourable spots on the globe, for making correct ob- 

 servations, and thereby arriving at truth on the present 

 subject. The country being new, the progress of clear- 



