need be said on this subject, since the amount of clothing needed
varies so greatly with the vitality of the individual. It has already
been pointed out that in rural communities the death-rate from
pneumonia, bronchitis, and similar respiratory troubles is much higher
than in urban communities, and it is quite possible that deficient or
unsuitable clothing is practically responsible for this.

The object of clothing is twofold: to protect the body against the
weather, particularly against changes in the weather, and secondly, to
protect the body against injury. Included in the former are the defenses
against the elements of cold, wet, and heat; while the protection
against injury is chiefly a matter of shoes. As has been pointed out, a
large part of the food consumed by the body is utilized in the
production of heat, whereby the body temperature is maintained at about
98 degrees Fahrenheit. A large part of this heat is continually being
lost from and through the skin by radiation and evaporation, and
evidently some regulating influence must be provided so that the amount
of heat given off may be adjusted to variations of the external
temperature. To be sure, the skin itself acts as a regulator, since a
rise in temperature causes the blood vessels on the surface to distend
so that a larger quantity of blood is distributed over the surface and
thereby more freely evaporated. Fall of temperature, on the contrary,
causes a contraction of the blood vessels and therefore a reduction in
the evaporation. But this is not sufficient where external temperature
undergoes wide variations, as in the northern and central parts of the
United States, and a modification of the clothing is a necessary
supplement. The main object of clothing, then, is not to keep out cold
or heat, but to preserve and make uniform the evaporation from the body.
It is an agent of the same sort as food in so far as the body
temperature is concerned, and without doubt light clothing requires a
greater amount of food; while, on the other hand, warm clothing will
make possible a lighter diet.

The best non-conductor of heat is still air, and if one could always
remain in quiet air, no clothing of any sort would be necessary, even in
the most severe weather, because the air itself would serve as a garment
and would prevent radiation from the body. Therefore, loose, porous
garments containing air in their folds and pores are much warmer than a
single, tightly wo