FOOD AND FUEL
OTHER: See that engine. Can you tell me what gives it the power or strength to draw its heavy load?
Helen: Steam gives it power.
Mother: And what makes the steam?
Elmer: The fire in the furnace makes the water boil, and steam comes from the boiling water.
Mother: Then the engine can do nothing unless it has fuel to burn and water to boil. It might be the best ever made, and yet do no work and have no power even to move itself. Do you suppose the engineer is careful to take plenty of the best fuel he can get, and to have a good supply of water, when he has a long journey and a heavy train?
Percy: I am sure he would be. I have read that it is counted one of the worst things an engineer can do to let his boiler get dry.
Mother: Well, in some ways our bodies are like the engine. Can you guess what the fuel is we must have?