WHAT MAKES US WARM?

Y thick, warm clothes make me warm," says some child.

No! Your thick, warm clothes keep you warm. They do not make you warm.

Take a brisk run, and your blood will flow faster and you will be warm very quickly.

On a cold day, the teamster claps his hands and swings his arms to make his blood flow quickly and warm him.

Every child knows that he is warm inside; for if his fingers are cold, he puts them into his mouth to warm them.

If you should put a little thermometer into your mouth, or under your tongue, the mercury (mẽr´ku r) would rise as high as it does out of doors on a hot, summer day.

This would be the same in summer or winter, in a warm country or a cold one, if you were well and the work of your body was going on steadily.

WHERE DOES THIS HEAT COME FROM?