Some of the work which is all the time going on inside your body, makes this heat.
The blood is thus warmed, and then it carries the heat to every part of the body. The faster the blood flows, the more heat it brings, and the warmer we feel.
In children, the heart pumps from eighty to ninety times a minute.
This is faster than it works in old people, and this is one reason why children are generally much warmer than old people.
But we are losing heat all the time.
You may breathe in cold air; but that which you breathe out is warm. A great deal of heat from your warm body is all the time passing off through your skin, into the cooler air about you. For this reason, a room full of people is much warmer than the same room when empty.
CLOTHING.
We put on clothes to keep in the heat which we already have, and to prevent the cold air from reaching our skins and carrying off too much heat in that way.
Most of you children are too young to choose what clothes you will wear. Others decide for you. You know, however, that woolen under-garments keep you warm in winter, and that thick boots and stockings should be worn in cold weather. Thin dresses or boots may look pretty; but they are not safe for winter wear, even at a party.
A healthy, happy child, dressed in clothes which are suitable for the season, is pleasanter to look at than one whose dress, though rich and handsome, is not warm enough for health or comfort.