HEATING AND VENTILATION 185 



Heating. There are two methods of heating gener- 

 ally in use. The direct method of heating is by a stove 

 or fireplace, or by a radiator for steam or hot water. 

 The indirect method is by means of a stream of hot air 

 from a furnace or steam coil in the basement. 



Direct method. The direct method by means of a 

 stove or fireplace gives better ventilation than when a 

 radiator for steam or hot water is used, since the rapid 

 movement of hot air up the chimney draws an equal 

 amount of air into the room through the cracks around 

 the windows and doors, and in the walls and floor. If 

 the house is tightly built, however, or if more than one 

 or two persons are in the room, this amount of fresh 

 air is not ordinarily sufficient and must be supplemented 

 by a proper opening of the windows and doors. If the 

 direct method of heating by means of a radiator is used, 

 no air is drawn out of the room and consequently but 

 little enters through the cracks, unless a heavy wind is 

 blowing. The windows and doors must therefore be used 

 more or less continuously, in order to insure adequate 

 ventilation. 



Use of windows for ventilation. If windows are to 

 be depended upon for ventilation, they must be intelli- 

 gently used with this end in view. When the wind is 

 blowing, the windows upon the windward side of a room 

 will give entrance to the air because of the wind pres- 

 sure. These windows should be opened more or less, as 

 determined by the force of the wind, and preferably 

 at the top, in order that the air entering may mix with 

 the warm air of the room and not settle as a cold draft 

 near the floor. If there is no fireplace or other means, 

 of exit for the air, one or more windows should also be 

 opened at the bottom on the leeward side of the room, 

 to permit the vitiated air to go out. When, as rarely 



