How ice is melted.
It is because heat goes from one thing to another that ice melts in warm water or warm air. Some of the heat in the water or air goes into the ice and melts it, and the melting ice cools the water or air by thus taking a part of its heat.
The heat which I have told you is made in our bodies spreads continually in the air around us. This is the reason that a room which is comfortably warm becomes uncomfortably so when a large company has been in it for a little time. A great deal of heat spreads into the air from so many bodies.
How fanning cools us.
Blowing on the fingers.
Did you ever think how fanning cools you? It is by making the heat go off faster from your body into the air. It moves off the air that has become heated by your body, and brings some other air to take its place. For the same reason, blowing upon any thing that is hot helps to cool it. It brings the air to it faster than it would come without the blowing, and so the heat passes off faster. But perhaps you will ask me to explain why it is that blowing on your fingers when they are cold warms them, when blowing on any thing hot cools it. This is plain enough. The air that you blow on to your fingers is warmer than they are, and gives some of its heat to them. If, on the contrary, your fingers were hot with fever, blowing on them would cool them, for they would then give some of their heat to the air that is cooler than they are.
Wood a poor conductor.
Heat spreads through some things more easily than it does through others. It spreads through iron very easily indeed, as you know by holding an iron poker with one end in the fire, but it does not spread any thing like as easily through wood. If you hold a stick of wood with one end in the fire, you can let it burn off without feeling the heat at the other end; but you could not hold a poker so long in the fire, for the heat would spread to the end in your hand so much that it would soon be too hot for you to hold it. So iron is said to be a better conductor of heat than wood, for the heat is conducted through it more easily than through the wood.
Wooden handles.