is curved in the
opposite direction, giving the form of the letter _S_ to the
supporting column of the body.

[Illustration: Fig. 33. The table is of proper height, the position is
correct, and the spinal column, 1, 1, is straight, while the shoulders
are of equal height.]

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What does fig. 33 represent?

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_Experiment._ Let a pupil be placed at a desk or table with one elbow
raised, as is frequently seen while writing, or at study, and observe
the condition of the shoulder and spinal column in this position.
Place another pupil at a table no higher than the elbow when it hangs
by the side while sitting, and observe the appearance of the shoulders
and spinal column. By a comparison of the two attitudes, the preceding
remarks will be comprehended and appreciated.

[Illustration: Fig. 34. The table is too high, and the position is
oblique and improper. The right shoulder is seen higher than the left,
while the spinal column, 1, 1, exhibits three curves.]

140. One shoulder may be elevated, and no injurious results follow,
provided care is taken not to keep it in the raised position too long,
or if the opposite shoulder is elevated for the same period of time.
The right shoulder projects more frequently than the left. This arises
from the greater use of the right hand with the shoulder elevated, and
not unfrequently the oblique positions assumed in performing the daily
vocations of life. With proper care, and by calling into action the
left shoulder, this deformity can be prevented.

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What experiment is mentioned? What does fig. 34 represent? 140. How
can one shoulder be elevated and no injurious results follow?

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[Illustration: Fig. 35. A representation of a deformed trunk.]

141. The loss of symmetry and diminution of height from deformed
spines are minor considerations, compared with the distortions that
the chest experiences, thereby impairing respiration and inducing
diseases of the heart and lungs. The invasion of the functions of
these two important organs lessens the vitality of the whole system,
and causes general ill health. Again, the curvature of the spinal
column is frequently attended by irritation and disease of the spinal
cord.

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Why does the right shoulder project more frequently than the left? How
can this deformity be prevented? 141. What is said of defo