Some Applications of Heat 



107 



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cold and damp in winter. This was especially unpleasant in sleep- 

 ing rooms. The coming of the stove was a great blessing to 

 mankind. 



All the ways in which heat is transferred are illustrated in 

 the use of stoves. Convection, however, is the most important 

 way in which the heat of stoves is distributed. The air over 

 the stove becomes heated and rises. Striking the ceiling, it is 

 turned aside toward the four walls, where it is cooled more or 

 less according to the number of windows in the room. As it 

 cools, it becomes heavier and, settling to the floor, flows back to 

 the stove where it is rewarmed and the process repeated. A gen- 

 eral circulation of the air is maintained as' long as the fire burns. 



The Jacketed Stove. A 

 wall of sheet iron is often 

 placed around a stove to pre- 

 vent too much radiation. Such 

 a stove is said to be jacketed. 

 It is frequently employed in 

 schoolrooms to insure proper 

 distribution of heat. When 

 the cold air enters at the 

 lower part of the jacket, con- 

 vection currents are set up 

 which carry the air, heated by 

 the stove and the jacket, 

 throughout the entire room. 

 When the stove is not jack- 

 eted it overheats all objects 

 near it, while objects in the 

 farther parts of the room 

 remain cold. As a result, 

 pupils sitting near an un jacketed stove in a schoolroom suffer 

 from too much heat while those sitting in the farthest parts of 

 the room suffer from cold. 



Hot Air Method. In using the hot air method, a furnace 

 is installed, usually in the basement of the house. A furnace is 

 a stove entirely surrounded by a metal jacket. Air pipes lead 



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A JACKETED STOVE 



Notice how the cool air rushes in to talce 

 the place of the warm air which rises. 



