ery cell in the body. They
carry news to the brain when anything touches them. The news produces
a feeling. Feelings are of three kinds:--

_First_, when anything touches the cells without harming them, we feel
a _touch_. We feel a touch by nerves in the skin. Those in the ends of
the fingers and tongue can feel the best. Those upon the back give but
little feeling.

Touch tells whether anything is hard, or rough, or round, or square,
or has other qualities and shapes.

_Second_, when anything touches the bare nerves or hurts the cells, we
feel a _pain_. We can feel a pain anywhere in the body. Pain tells us if
we are being harmed. If we had no feeling of pain, we might be killed
before we could know of our danger. Pain warns us away from danger.

_Third_, we can feel _heat_ and _cold_. Anything very hot or very
cold, however, makes only a pain and gives no feeling either of cold
or of heat.

=164. Sight.=--We see with our eyes. An eye is a hollow ball. In its
front is a clear window. Behind the window is a round curtain with a
round hole in its middle. When we speak of the color of the eye, we
mean the color of this curtain. Light passes through the hole in the
curtain and falls upon some nerves in the back of the eyeballs. There
it forms a picture like a photograph. The nerves carry this picture to
the brain, and we see it.

[Illustration: =The human eye.=

_a_ bony case of the eye.
_b_ muscle to move the eye.
_c_ and _d_ coverings of the eye.
_e_ lining or seeing part of the eye.
_f_ eyelid.
_g_ colored curtain or iris.
_h_ and _i_ clear windows of the eye.]

=165. Movements of the eyes.=--We can turn our eyes so as to look in any
direction. Sometimes a person has one eye turned sidewise. Such a person
is cross-eyed, and sees well out of only one eye at a time. Glasses may
help the eyes, but sometimes a surgeon has to cut a tiny muscle.

=166. Coverings of the eyes.=--The eyeballs lie in a bony case, upon a
soft bed of fat. In front each is covered with two lids. We can shut
the lids to keep out dust and insects. When we are sleepy, they come
together and cover the eyes. Little hairs at their edges help to keep
out the dust.

Sometimes a little dirt gets under the lids. Then the eye smarts or
itches, and we want to rub it; but this may grind the dirt in deeper.
Then you should get some one else to lift your eyelid and pick out the
dust with a soft handkerchief. If you cannot get help, li