AND MARSHY SITUATIONS. 135 



pended refpiration would retain its irritability for fome 

 time ; but this is not the cafe. 



From the facfts and obfervations which have new been 

 ftated, I think it may be fairly concluded, that the cauies 

 of the unwholefomenefs of low and moiil: fituations in the 

 fummer and autumnal months, is not owing to any in- 

 vifible miafmata or noxious effluvia, which ifliie from 

 the foil and lurk in the air, but to a very different caufe, 

 viz. to a deficiency of the oxygenous portion of the at- 

 mofphere in fuch fituations, in confequence of vegetable 

 and animal putrefadlion, in conjundion with the exhauft- 

 ing, and debilitating heat of the days, and the fedative 

 power ofthe cold and damp air of the nights. 



For want of the refrefhing and falutary ftimulus of 

 pure air, all the fundlions ofthe body are performed im- 

 perfeftly and languidly. The nervous fyftem in particu- 

 lar, becomes pretematurally fufceptible of impreflions 

 from every change that occurs in the temperature of the 

 furroundmg atmofphere. The application of or cxpo- 

 fure to a damper and colder ftate of the air than ufual, 

 renders the veflcis on the furface of the body powcrlefs, 

 and atonic, the brain and heart fympathife with the ex- 

 treme nerves and veflels, the power of every function 

 of the body declines, till the heart roufed by accumulating 

 blood reafts with increafuig velocity, and is relieved of 

 the unufual burthen. 



That the cauf s which I have now afligned, are the true 

 ones is rendered next to certain, from the frequent occur- 

 rence of thofe difeafes, (which have heretofore been fup- 

 pofed to depend upon the operation ot fpecific miafmata), 

 in fituations remote from mardiy ground, particularly in 

 large and populous cities, where fedentary occupations and 

 want of ex'^rcife, render the inhabitants delicate and in- 

 firm. 1 have feen numerous inftances of this kind even 

 in the "winter feafon, when no effluvia from marfhes 

 S 3 could 



