ut headache.

=Keeping the Eyes Well.=--Bits of dirt often get beneath the eyelids
and cause much pain. By taking hold of the eyelashes the lid may be
pulled out from the eye and any dirt removed with the corner of a
clean handkerchief passed gently along the lid.

The eyes sometimes become sore because they are rubbed with soiled
fingers on which are germs. These germs get inside the lids and grow,
and in this way poison the eyes. Unless care is used sore eyes are
likely to spread from one child to another in the school. The sick child
rubs its eyes and then handles a book or pencil on which the germs are
smeared by the fingers which touched the eyes. The next child picks up
the same book later, gets the germs on the fingers, and then rubs the
eyes. For this reason you should never rub the eyes. If you have sore
eyes, _be careful that no one else catches the sickness from you_.

=The Ear.=--The ear is made of three parts called the _outer ear_, the
_middle ear_ or _eardrum_, and the _inner ear_. The outer ear is made
of a plate of skin and gristle and a slightly bent tube about one inch
long. At the inner end of this tube is a thin membrane or _drumhead_.
Beyond the drumhead is the cavity of the middle ear about as large as
a pea. A chain of three tiny bones stretches from the outer drumhead
across this cavity to a tiny _inner drumhead_. Beyond the inner
drumhead is the inner ear.

[Illustration: FIG. 92.--View of the ear from in front. Three little
bones stretch across the middle ear.]

The middle ear is kept full of air by means of a tube leading from it
to the throat. A cold or other sickness may cause this tube to fill up
and make you deaf. The inner ear consists of a sac and four bent tubes
filled with a watery fluid. They are also surrounded by watery fluid
contained in channels in a bone of the skull. The end of the nerve of
hearing is on one of the tubes.

=How we Hear.=--Throwing a stone in the water makes waves which move
farther and farther outward. In the same way a noise causes waves in
the air. These waves pass into the ear tube, strike the outer
drumhead, and make it move. This moves the chain of bones in the
middle ear so that they cause motion in the inner drumhead. This in
moving back and forth makes waves in the fluid of the inner ear which
strike on the ends of the nerve of hearing and cause messages to be
carried to the brain.

=Care of the Ears.=--The ears should not be struck or pulled, a