The Washington herald., 1910-03-19
HANDS NOT THERMOMETERS.
Because of One of Natures Wonder
fuI Heat Regulating Devices.


The man was talking first about get
ting into hot water with his wife, but he
switched from the metaphorical subject
to the real goods. says the New York
Sun.
did you ever watch a thermometer in
a basin into which you were turning hot
water mixed with eold?" he said. AS
more hot water is turned IN the mercury
rises swiftly, but regularly.
But if you use your hand instead of
the thermometer, youn not get any i'm
preston Of the even. swift rise of the
temperature. It's curious 70 see how
really absurd a heat measurer the hand
can be.
The only cold water in the basin has
the hot added to 1t. Put your hand in
and feel The thermometer begins to
rise at once. but your hand lags behind.
You don't get an impression of increas-
ing heat. The thermometer keeps rising
Your hand tells you that the water is
getting warmer slowly.
1.-The water gets lukewarm. then still
warmer, then hot. then almost boiling.
You watch the mercury racing up the
scale. but your hand still lags away be-
hind Suddenly, without warning. point
is reached IN the water temperature at
which the hand makes up for all the de-
lay II has shown before.
THE water appears changed by magic,
for you feel the pleasantly warm water
alter in a second from comfortable heat
TO a painful condition. and you pull your
hand out Of the water instantly. In that
second the water appears to climb
through a hundred degrees OF tempera-
ture, although your thermometer tells
you It has only risen two or three de-
grees.
THE hand lags behind partly because
the water is at an ordinary normal tenn
perature, between 50 degrees and 100 de-
grees, TO which the hand is accustomed,
and partly because the water is drawing
heat away from the hand
But at IS degrees, blood heat, the wa
ter commences to add heat to the hand.
As it rises It has first to give back 10 the
hand the heat 1t robbed it Of while below
blood heat. and the increase is not felt.
Jill AA9aAl6 III temperature anu ldFALlS
given back the heat it took away, the
hand does not even then feel the increase
noticeably. This is because the blood cir
culation is carrying it away from the
hand and distributing It.
THE water gets still hotter The blood
carries away more and more heat. pro-
tecting the hand from injury. Then a
certain point is reached when the blood
absorbs all the heat It can carry. Let the
water rise single degree above this
temperature and the hand accumuiates
heat Then the apparent heat races up
like lightning.
This is natures wonderful protection
against sudden changes Of heat. It is
her warning of danger.
Mature hasn't any protection against
slow changes Of heat. Put your hand In
the water again IT stings with the heat
given out. Hold It there.
"Ar at once the water appears cooler.
though the Thermometer tells you II isn't.
A second protection Of nature Is coming
into play-accommodation
Turn the boiling water on gently and
slowly. keeping your hand in the water.
Increase the heat very slowly and imper-
ceptibly so that the thermometer rises a
degree minute. You don't notice It.
Z You can finally get the water In the
basin up near the boiling point but the