Anah)fis of the Air. 257 



fires arc continually carrying a large ftream 

 of heated air out of the rooms up the chim- 

 ney, which dream mud neceffarily be fup- 

 plied with equal quantities of frefh air, 

 thro' the doors and windows, or the cranies 

 of them. 



And thus many of thofe who have weak 

 lungs, but can breath well enough in the 

 frefh country air, are greatly incommoded 

 in their breathing, when they come into 

 large cities where the air is full of fuliginous 

 vapours, arifing from innumerable coal fires, 

 and flenches from filthy lay-ftalis and fewers : 

 And even the mod robuft and healthy 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 elaftick 

 air, a freer courfe is thereby given to the 

 blood, and probably a purer air mixed with 

 it $ and this is one reafon why in the coun- 

 try a ferene dry conftitution of the air is 

 more exhilarating than a moift thick air. 



And for the fame reafon, 'tis no wonder, 

 that peftilential, and other noxious cpide- 



S micai 



