SCHOOL HYGIENE 



429 



Sometimes two methods of heating are employed. Fresh 

 air is forced into the rooms at about the desired temperature 

 to provide ventilation, and the exact temperature is con- 

 trolled by means of steam or hot-water radiators placed in 

 each room. The temperature is controlled by means of 

 thermostats which control the valves on these radiators. 

 This combination makes a very satisfactory heating and 

 ventilating system, when properly cared for. 



FIG. 170. School ventilating system that supplies warm air of correct humidity. 



Ventilating one-room schools. For heating small, one- 

 room, rural schools a jacketed stove is widely used. The 

 stove is surrounded with a jacket of some sheet metal which 

 extends down to the floor and is open at the top. Fresh 

 air is brought in from the outside by means of a duct con- 

 necting with the jacket. As the air is heated, it rises and 

 passes out into the room. The foul air is removed by means 

 of an opening in the chimney near the floor or by means of 

 a pipe connected with the chimney and extending down to 

 within a foot of the floor. 



