IJO 



THE PHILOSOPHY 



Upon the whole, as the air we continually breathe Is an unlver- 

 fal menftruLim, and, of courfe, liable to be impregnated with exha- 

 lations from every fubftance to which it has accefs, the great impor- 

 tance of perfonal, as well as of domeftic cleanlinefs, is an obvious 

 refledlion. In building towns or houfes, the fituation, with regard 

 to air, is a capital objed. The vicinity of marfhes, of ftagnating 

 waters, of manufadlures of tallow, oil, fal ammoniac, the fmelting 

 or corroding of metals of every kind, and many other operations 

 which contaminate the air, fliould be either avoided or removed, as 

 they are the pefts of our fenfes, and the poifoners of our conftitu- 

 tions. P'ven in northern climates, houfes furrounded with trees, or 

 in the neighbourhood of luxuriant vegetables, are always damp, 

 and infefted with infedls ; and hence the ambient air is replete with 

 the feeds of dlfeafe. Precautions of this kind are ftill more necef- 

 fary in hot climates. Air, like other menftruums, abforbs a greater 

 or lefs proportion of the particles of bodies, according to its degree 

 of heat. In Madrid, however, in Conftantinople, and in many 

 other cities of warm regions, the houfes are crouded together, the 

 ftreets are narrow, and covered with filth of every kind. We can- 

 not, therefore, be furpriled, that human beings exifting in fuch fi- 

 tuations fhould be fo frequently infected with peftilential difeafes. 



CHAP. 



