The daily morning journal and courier. [volume] (New Haven, Conn.) 1894-1907, 1907-07-30
The HUMAN body
AS affected BY AIR
Conditions Under Which It
Is Made Most Com
Portable.
DAMP AIR HARD TOBEAR
Wind a Great Factor-Calm
and Dry Air the Least
Annoying.
DAMP AIR HARDTOBEAR
Annoying.

~ set forth by Van Bebber, is accom-
plished by means of three familiar ply
steal rocesses-ccnduction radiation,
evaporation. The amount of heat lost
by conduction depends on the difference
of temperature between the body and
the surrounding air, and upon the con-
ductivity Of the air. Other things being
equal, the colder the air the greater
the cooling by conduction; the warmer
the air, the less. Hence conduction may
b. expected to be at maximum in
winter Secondly when there is wind,
more heat is lost by conduction. Ev-
cry one knows that severe cold which
may be easily endured when the air is
calm may become unbearable when
there is even slight movement of the
air. The springng up of a breeze on a
bright, cold winter day may change the
temperature which we feel from an
agreeable one to one which is decidedly
chilly, although the thermometer shows
no change at all. The difference be-
tween calm cold and windy cold is very
strikingly brought out in the report
from Arctic and Antarctic exploring
expeditions Temperatures Of 20 degrees,
80 degrees, even 40 degrees below zero
are dscribd as being comfortable when
there is no wind. hansen, for example,
says on one occasion THE tempera-
ture to-day is 40 degrees Fahrenheit be-
low zero, but there is no wind, and we
have not had such pleasant weather
for walking for q long time; it feels
almost mild when the air is still" Sim
liar statements may be found in abun-
dance in the writings of other Arctic
explorers it being frequently noted that
the heavy clothing was too warm at
these very low temperatures. In the
polar regions, then, the feeling of cold
and the reading of the thermometer are
not in any closer agreement than they
are here. Naturally, high temperatures
are more comfortable with some wind
Thirdly, the moisture of the air is an
Important consideration in this matter,
for damp air Is better conductor than
dry air. Hence, in winter damp cold
is so much harder to bear than dry
cold. The damp northeast winds on the
New England coast in winter often feel
colder than dry northwest winds which
have lower temperature, although the
velocity may be the same in the two
cases. Obviously, however, evaporation
enteEs in to complicate this question Of
conduction somewhat.
The amount of heat lost by the body
through radiation depends on the tenn
fi,tse apd thA n ipor .
surrounding objects, such, as walls,
pavements, vegetation, furniture etc.
1t is conceivable that one should be
so placed that the temperature of all
surrounding objects, and of the air as
well, should be just the same as the
body temperature. In such a case the
body would lose nothing by radiation.
Nor would it lose anything by con-
duction. The only loss would be by
evaporation, unless the air were sat
urated, In which case the conditions
would be unbearable for any length of
time. When radiation is checked, as by
the presence of many persons crowded
together by the proximity of hot walls,
pavements, etc, the body may suffer
serious consequences, as in the case Of
prcstration by the heat and sunstroke,
which, as is well known, usually attack
people who are exposed under rather
special conditions, as, for example, la
borers on sewers and railways masons
and painters close to the walls of build
ings, etc, When troops are on the
march 1t has been shown that the men
who suffer most are in the middle of
the column, where they can lose least
heat by radiation.
II is difficult to consider the adjust
ment of the body to the temperature
conditions Of the air without taking
account of evaporation, which is of very
great Importance, and is almost always
in operation to greater or less de-
gree. The human body in health has
not a dry surface, like the dry-bulb
thermometer, but is more or less moist
because of the emulation of perspiration
through the pores of the skin. When
this moisture evaporates, the skin cools
through the loss of heat which is re-
CURED in the process of evaporation.
Cramer has shown that the amount Of
water lost through Precipitation during
q hot summer day, If man is kept at
hard work. may reach between seven
per cent. and eight per cent. of the
weight of his body. Other things being
equal there is more evaporation the
warmer, the drier, and the less ouiet
the air The hotter the air. the greater
its capacity for water vapor, the drier
the air, the more water can still be
evaporated into it; the more wind. the
greater the opportunity for evaporation
into it; the more wind, the greater the
opportunity for evaporation into the
fresh supply Of air which is constantly
brought to the body, If the air be COM
pletely saturated at the body tempera-
ture, there can be no evaporation: but
IL the air be saturated below the body
temperature the body warns the air
nearest it; in so doing the capacity of
the air for water vapor is increased,
and evaporation may then begin again.
Even If the temperature of the air be
$50 degrees, unless the air is saturated
the body can cool by exaparation. 1t has
been shown that when the air is very
dry human beings can endure extraor-
dinarily high temperature, as in the
case of a man who stayed 20 minutes
in dry air at 212 degrees, Hot dry air
in motion is mach cooler than hot dry
air at rest, and hot moist air is OPP
pressive because there is little oppor-
tunity for evaporation. The moist heat