free
transpiration from the skin, and likewise convey the excreted fluids
from the surface.

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665. What is said of linen as an article of apparel? 666. Why is
light-colored apparel best adapted for every season? What is said of
the apparel of coach-drivers? 667. Why should we wear porous
clothing?

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668. The necessity for this is illustrated in wearing India rubber
over-shoes. If they are worn over boots ten or twelve hours, not only
the hose, but the boots will be moist from retained perspiration, and
the residual matter left in contact with the skin may be reconveyed
into the system by absorption, causing headache and other diseases.
Cotton and woollen fabrics are not only bad conductors of heat, but
are also porous; for these reasons, they are well adapted to transmit
the excretions of the skin.

669. _The clothing should be not only porous, but fitted loosely._ The
garments should retain a layer of air between them and the body. Every
one is practically aware that a loose dress is much warmer than one
which fits closely; that a loose glove is warmer than a tight one; and
that a loose boot or shoe affords greater warmth than one of smaller
dimensions. The explanation is obvious; the loose dress encloses a
thin layer of air, which the tight dress is incapable of doing; and
what is required, is, that the dress should be closed at the upper
part, to prevent the dispersion of the warm air, by the ventilating
current which would be established from below.

_Observation._ As the purpose of additional garments is to maintain a
series of strata of warm air within our clothing, we should, in going
from a warm room into the cold air, put on our defensive coverings
some little time previous, in order that the layers of air which we
carry with us may be sufficiently warmed by the heat of the room, and
not borrowed from the body on exposure to the cold.

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668. How is the necessity of porous clothing illustrated? 669. Why
should we wear loose garments? What is the use of additional garments
when going from a warm to a cold air? When should they be put on?

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670. _The clothing should be suited to the temperature of the
atmosphere and the condition of the individual._ The invariable rule
should be, to wear enough to maintain an equal and healthy action of
the skin. Care should be taken, however, that the action o