or, should be held at an appropriate distance
from the eye. Were this attended to by the parent or instructor, we
should not see so many persons with defective vision.

940. Cleanliness, as well as the health of the eye, require that it be
bathed every morning with pure water, either cold or tepid,
accompanied with as little rubbing or friction as possible. In all
instances, the secretion from the lachrymal glands, that sometimes
collects at the angle of the eye, should be removed, as it contains
saline matter.

941. When small particles, or dust, get upon the eye, they produce
much inconvenience, which is often increased by harsh attempts to
remove them. The individual should be placed before a strong
light, the lids held open with one hand, or by another person, and
the particles removed with the corner of a fine linen or silk
handkerchief.

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938. What is the effect of repeatedly using the eye in one direction?
939. Why are artisans and scholars generally short-sighted? Why are
sailors and hunters long-sighted? How can defective vision in a great
degree be prevented? 940. What reasons are there for bathing the eye?
941. How can dust and other small particles be removed from the eye?

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942. Sometimes the substance is concealed under the upper eyelid, and
it may then be exposed by turning back the lid in the following
manner: Take a knitting-needle, or small, slender piece of stick,
which is perfectly smooth, and place it over the upper lid, in contact
with, and just under the edge of the orbit; then, holding it firmly,
seize the eyelashes with the fingers of the disengaged hand, and
gently turn the lid back over the stick or needle. The inner side of
the lid can then be examined, and any substance removed that may have
been there concealed. Too many trials ought not to be made, if
unsuccessful, as much inflammation may be induced; but a surgeon
should be consulted as soon as possible.

_Observation._ Eyestones ought never to be placed in the eye, as they
often cause more pain and irritation than the evil which they are
intended to remedy.

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942. How removed from the upper eyelid? Why should not eyestones be
used?

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CHAPTER XLVI.

THE SENSE OF HEARING.

943. The sense of hearing is next in importance to that of vision.
Through this sense we are enabled to perceive sounds, that not only