22 



FARM DEVELOPMENT 



Figure. 1. Engine with single steam chest. 



temperature, the active heat from the hot water will 

 again be given off, the heat radiating into the colder 

 surrounding air, while none will be given off from the 



other kettle which has 

 remained at the freezing 

 temperature. 



The coal or wood used 

 in the engine has heat, 

 or energy, in a latent 

 form, and by setting it 

 on tire this heat, so to 

 speak, is extracted from 

 the fuel, while the com- 

 pounds of which the fuel 

 is made are destroyed or broken down into simpler chem- 

 ical compounds. The part of the wood which the tree 

 got from the soil as mineral plant food is left on the 

 grate when we use the wood as fuel, and we call it ashes. 

 That part of the fuel which the plant got from the air 

 becomes gas again, and goes up the chimney as a part of 

 the smoke. The heat gathered from the sun's rays is 

 liberated from the 

 fuel and is radiated, or 

 thrown off. It may be 

 conducted into water 

 in the boiler of the 

 engine and cause the 

 water to expand into 

 steam. When the heat 

 from the fuel in the fire- 

 box under the boiler 

 has been transferred 

 to the water in the 

 boiler and has changed it into steam, we have this 

 force in a very active form expanding the steam. 

 By conducting this active steam to the cylinder of 



Fig 



The tandem compound engine, Figure 

 2, has a second steam chest, which uses the ex- 

 haust, or partially used steam, from the first 

 chest, thus securing 10 or 15 per cent more energy 

 out of the steam than the engine with a single 

 steam chest. 



