260 Jnal)fis of the Air. 



of frelh air, through the doors and windows, 

 or the cranies of them. 



And thus many of thofe who have weak 

 lungs, but can breathe well enough in the 

 freih country air, are greatly incommoded 

 in their breathing, when they come into 

 large cities, where the air is full of fuligi- 

 nous vapours, arifing from innumerable coal 

 fires, and ftenches from filthy lay-ftalls and 

 fewers : And even the mofl robuft and heal- 

 thy, in changing from a city to a country 

 air, find an exhilarating pleafure, arifing from 

 a more free and kindly infpiration, whereby 

 the lungs being lefs loaded with condenfing 

 air and vapours, and thereby the veficles 

 more dilated, with a clearer and more ela- 

 ftick air, a freer courfe is thereby given to 

 the blood, and probably a purer air mixed 

 with ic ; and this is one reafon why in the 

 country a ierene dry conflitution of the air 

 is more exhilarating than a moift thick air. 



And for the lame reafon, it is no wonder, 

 that peffilentral and other noxious epidemi- 

 cal infections are conveyed by the breath to 

 the blood (when we confider v/hat a great 

 quantity of the airy vehicle lofes its elafti- 

 eity among the veficles, whereby the infe- 

 ctious Mia/ma- is lodged in the lungs). 



When 



