890 Transactions of the American Institute. 



fashioned fire place or the more modern coal grate is the best contri- 

 vance for warmiTig, But a strong objection is, as we have stated, the 

 drafts of cold air induced ; added to this is the great expense. In 

 fact, the latter objection is so great that these methods have been 

 already entirely abandoned. 



Few persons seem to understand just how the air in a room is 

 warmed. It is generally thought that the air in immediate contact 

 with the burning fuel or the heated stove is warmed, and that this 

 warms another, and so on until all the air in the room is warmed. 

 Not so at all. The air next to the burning fuel, in the case of the 

 open fire, is warmed, and, for the most part, goes up the chimney. 

 A small part, however, arises, and the cold air takes its place. The 

 heated air that rose slowly cools, and is displaced by the warmer 

 and rarer air just escaped from immediate contact with the fire, and, 

 after a time, falls, and is again wawned. So that we see only a small 

 part of the air of the room is warmed, while -whole oceans are heated 

 and escape from the chimney. If a stove be used for heating, only a 

 small part of the air comes in contact with the burning fuel ; in 

 fact, just enough to oxydize the fuel, while the air about it is heated 

 and rarified, and then pressed up by the cooler and heavier air, 

 which is in turn heated and forced up, and thus we have a current of 

 air established, moving towards the stove, then up to and along the 

 ceiling, then down to be warmed again. But as this current takes 

 place in a closed room, and the tighter the better, we think, of course 

 it is the same air, moving in a circle, to which we are constantly 

 imparting the carbonic acid of the breath, which is warmed and cir- 

 culated and breathed again ; and, if our rooms were absolutely air 

 tight, in a short time the air would be so saturated with carbonic 

 acid as to produce death. We shall never be able to tell how much 

 we are indebted to green lumber and indifferent workmen. 



Another method of heating is by driving steam through coils of 

 iron pipe. Not only does this method of warming render ventilation 

 impossible, but it is, perhaps, the most uneconomical. 



Now, heat may manifest itself in two ways, viz. : As temperature and 

 as expansion. All the force generated by the burning fuel will appear 

 in one of these forms, or a part of both. Water at the normal pressure 

 can be heated to only 212 deg. Fahrenheit. Consume as much fuel 

 as you will, and the water will remain at 212 deg. Fahrenheit. But 

 the force generated by the consuming fuel is not lost, but is transmitted 

 to the water in the form of expansion, and the Avater is converted 



