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R E F A C E 



T O 



THE THIRD VOLUME. 



IT may be queftioned, whether woods are to be confidered any 

 further detrimental to the air of their neighbourhood, than as 

 they may obftrudt the free paflage of refrefhing gales ? 



It is the opinion of an ingenious gentleman, who refided for many 

 years in the Weft-Indies, that local unhealthinefs in that part of the 

 world has been moft remarkable on fpots newly cleared of their 

 native woods j that for this reafon, a refidence there is generally 

 unwholfome to the firft fettlers, though not always To to the firft 

 cultivators. The land in fuch places is covered to fome depth 

 with a mould, which has been gradually depofited and encreafed by 

 the trees, plants and vegetables, fpringing up, growing and rotting 

 upon the furface for ages ; fo that an acceffion of foil has been 

 gained every year, by the fucceflive decay of thefe vegetable races. 

 While it continues overfhadowed with thick forefts, equally im- 

 pervious to the fun and winds, the foil lies in a kind of inactive 

 ftatej but no fooner is it laid open to thofe influences, and the 

 copious abforption of dews and (howers, charged with volatile, 

 putrefadive particles, than a ferment or inteftine motion is excited ; 

 and vapoury fteams begin to afcend in great abundance, which are 

 prejudicial to human health. So, after thefe opened fpots have lain 

 for fome fpace of time thus expofed, the fermentation gradually fub- 

 lides, and, the materials which gave birth to thefe pernicious effluvia 

 being exhaufted, the air becomes amended, and the mortality ceafes 

 with the caufes of it. 



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