VENTILATION OF KOOMS. 



257 



VEXTILATIOX. 



Impure air may be breathed for a short time without 

 any serious detriment, but to live in it and respire it for 

 years can not fail to produce permanent injury to the 

 health. During the heat of summer, open doors and win- 

 dows Avill usually furnish plenty of fresh air, so long as 

 this season lasts, which in the Northern States is not one 

 half the year. During the rest of the time, rooms are 

 heated with close stoves, and unless special care is taken 

 to secure fresh air, pale or sickly inmates Avill be the most 

 likely results. 



Even Avith a common open fireplace, which causes more 

 circulation of the air in a room than stoves, the ventila- 

 tion is very imperfect. The following figure (fig. 282) 



represents the fresh air 

 as passing in from an 

 open window opposite 

 the fire, producing a 

 direct current from the 

 window to the chim- 

 ney, and leaving all the 

 upper portion of the 

 room filled with bad 

 air, unafifected by the^ 

 change. The cold air 

 can not rise, nor the 

 hot air descend. This 



Fis:. 2S2. 



A hadlij-vtnUlaLed Room. 



difficulty may be easily removed by placing a register 

 (which may be closed or opened at pleasure) at a, in the 

 upper corner, so that the confined air may escape into the 

 chimney. Without this provision, it is nearly impossible 

 to preserve the air in proper condition for breathing, for 

 the upper part, being warmest and lightest, remains un- 

 changed at the top. In rooms heated by stoves, registers 

 for the escape of the foul air are still more important, where 



