VENTILATING THE HDME 



2 9 



we can by means of doors and windows. A certain amount 

 of ventilation takes place through the walls of houses and 

 around the windows and doors. When a system of hot-air 

 heating is used by means of which fresh air is forced into the 

 room, other air must be forced out through these cracks and 

 this provides some ventilation, sufficient perhaps for a small 

 family but not enough for a schoolroom. In the hot- water 

 or steam system, when radiators are placed in the rooms 

 with no provision 

 for bringing in fresh 

 air, the amount of 

 ventilation brought 

 about by means of 

 the cracks around 

 the windows is in- 

 adequate. This is 

 especially true of our 

 modern houses which 

 are made more com- 

 pletely air tight than 

 formerly. Often too 

 in northern climates 



FIG. 7. Ventilation by window. 



they are provided with storm windows, which tend to keep 

 out the fresh air that might otherwise have entered. 



Ventilation may be secured by opening windows on differ- 

 ent sides of a room, and a board may be placed in front of a 

 window to break the strength of the wind. One excellent 

 way of providing ventilation without lowering the tempera- 

 ture of the room is to fit a frame to the lower window like a 

 mosquito screen, so that the window may be lifted and the 

 frame placed under it. This may be made any height, and 

 covered with ordinary cotton cloth. This allows the fresh air 

 to enter but prevents the room from being suddenly cooled, 

 as the cloth does not lose heat much faster than the glass in 

 the window. 



