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are lighter than those of the lean and large-boned, and of men; and the
specific gravity of the water of a river is somewhat influenced by the
presence of the tide from sea. But, leaving this tide out of question,
it may be said that very few human bodies will sink at all, even in
fresh water, of their own accord. Almost any one, falling into a river,
will be enabled to float, if he suffer the specific gravity of the water
fairly to be adduced in comparison with his own--that is to say, if
he suffer his whole person to be immersed, with as little exception as
possible. The proper position for one who cannot swim, is the upright
position of the walker on land, with the head thrown fully back, and
immersed; the mouth and nostrils alone remaining above the surface.
Thus circumstanced, we shall find that we float without difficulty and
without exertion. It is evident, however, that the gravities of the
body, and of the bulk of water displaced, are very nicely balanced, and
that a trifle will cause either to preponderate. An arm, for instance,
uplifted from the water, and thus deprived of its support, is an
additional weight sufficient to immerse the whole head, while the
accidental aid of the smallest piece of timber will enable us to elevate
the head so as to look about. Now, in the struggles of one unused to
swimming, the arms are invariably thrown upwards, while an attempt is
made to keep the head in its usual perpendicular position. The result
is the immersion of the mouth and nostrils, and the inception, during
efforts to breathe while beneath the surface, of water into the lungs.
Much is also received into the stomach, and the whole body becomes
heavier by the difference between the weight of the air originally
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