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, 



: ft ^ suppose you shut all 



*-..*,. ;.''; '' ';., the windows of your 



l:: v% \#ny*~ ._,J^ room and light a joss- 

 ,-w-^* 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 find 

 that it pours in at one window while 

 the smoke streams out of the other, 

 and the room is cleared in almost no 

 time. Of course the impure air is pour- 

 ing out of the room with the smoke, 

 and the pure air is coming in just as 

 fast, though we do not see it. 

 Stop just here ; look around the room you are in and 

 see whether you can tell how the fresh air gets in and 

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

 the windows. Notice which are shut and which are 

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



CIRCULATION OF AIR 

 IN A ROOM 



