22 



GOOD HEALTH 



If the house is old-fashioned, probably the only way is 

 by opening doors and windows. This is a good deal of 

 trouble sometimes; nevertheless, it must be done. To 



show how little time it 



&'"' takes to change the air, 



%,. " : %^ "') suppose you shut all 



'"^:C=: ' :; %..-, - ( ": : ; the windows of your 



t .... %J^Y.<" J$? room and light a joss- 

 stick. See how quietly 

 the smoke floats around here and there. 

 Soon the room is quite full of it. Now 

 open windows on opposite sides of the 

 room and see what happens. 



If a breeze is blowing in the right 

 direction out of doors, you will fine 

 that it pours in at one window whil< 

 the smoke streams out of the othei 

 and the room is cleared in almost n< 

 time. Of course the impure air is pour- 

 ing out of the room with the smoki 

 and the pure air is coming in just 

 fast, though we do not see it. 

 Stop just here; look around the room you are in an< 

 see whether you can tell how the fresh air gets in an< 

 how the bad air gets out. You may have to judge b; 

 the windows. Notice which are shut and which ai 

 open, and see if the wind is blowing; then try to decid< 



CIRCULATION OF AIR 

 IN A ROOM 



