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 (m[~e]r'ku r[)y]) 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?

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.

When you feel cold, take exercise, if possible. This will make the hot
blood flow all through your body and warm it. If you can not, you should
put on more clothes, go to a warm room, in some way get warm and keep
warm, or the cold will make you sick.

TAKING COLD.

If your skin is chilled, the tiny mouths of the perspiration tubes are
sometimes closed and can not throw out the waste matter. Then, if one
part fails