Evening star., 1932-02-09
SCIENTISTS STUDY
HUMAN RADIATION
Body Revealed as ExChang-
ina Heat Waves With Sur
rounding Objects.
Every human body is a radiator

Every human DOdy Is TaQlatOT,
keeping up a constant exchange of
heat waves with surrounding objects.
Almost half the heat lost by an indi-
vidu9l is given off in this way. In
order to remain alive, Q Warm-blooded
organism must mainbain a constant
relationship between The heat that it
radiates and the loat that it receives
by radiation from Is surroundings.
This human radia ion. essentially the
same as the heat RdiatiOn of a stove
Or star, is the subject of an intensive
study with important practical appli-
cations now being conducted at the
Smithsonian Institution.
1t becomes of immediate significance,
according to a report Just issued by DR..
/. B. Aldrich of the staff of the AStro-
physical Observatory, in connection
with such matters as the heating and
seating arrangements of school rooms
where dozens Of healthy human bodies
are exchanging heat with each other,
the desks walls, radiators and black
boards. Also it becomes very compli
Gated.
Demand on Body.
BY application Of we'll known radia-
ton formulas Mr. Aldrich finds that
on q cold Winter day, when the tenn
perature Of a school room wall in direct
contact with the chilly air outside
might easily be about 10 per cent
lower than the air temperature of the
room, a child might radiate twice as
much heat from the side of its body
nearest the wall than from the other
side. Thus there would be a 25 per
cent increase in the total amount be-
ing radiated, and a consequent demand
on the body for the production of
more heat.
'Of even greater importance" Aldrich
says, lis the condition of the surround
ing objects which are at higher than
air temperature. Suppose the mean
surface temperature of clothed subject
to be SO degrees Fahrenheit and the
temperature of the surrounding walls to
be raised to the same figure from about
II degrees Fahrenheit. Radiation loss
from a human subject now would be
negligible, the normal balance between
heat produced and heat lost would be
destroyed. and condition of discom-
fort would result until readjustment
was made. In actual school room con-
ditionS a student near an unshielded
steam radiator or other artificial heat
source is exposed to temperature
much higher than his surface tenn
perature.
In classes the student is surrounded
by other students. AS a rough example,
assume a class placed in rows, with
spaces of 2 feet between students in
a row and the same distance between
rows. Imagine each student to be
cylindrical, foot in diameter and
feet high.
10 Per Cent of Space.
THE four students nearest to a
given student would occupy roughly 10
per cent of the space to which a central
student is radiating. The amount of
space occupied by all the surrounding
students would be about 20 per cent
of the total space to which the central
student is radiating.
If we reduce the space between STU
dents to only foot the area occupied
By the other students increases to
about 35 per cent Of the whole. For
spacing of feet it reduces to only
10 per cent. In other words, when
students are spaced l foot apart, the
total radiation loss of each is some 35
per cent less than if he were alone in
the room. When the spacing is
feet the radiation loss is 10 per cent
less
The radiation from a human being,
Mr.. Aldrich found, is almost entirely
from the skin and clothing. The heat
produced by the food combustion proc
eSses inside the body is transferred to
the outer surfaces by circulation of the
blood Human skin, measurements
in the Smithsonian laboratory showed.
is an almost perfect nOn-transmitter of
the long-Wave radiation which is felt as
heat.
Clothing Counts Most.
Approximately 78 per cent of the
total human body radiation, Mr..
Aldrich found, comes from the clothing.
This amount is slightly higher for
boys than for girls.
The shoes are responsible for an ad-
ditional or 10 per cent. Approx
mately 8 per cent comes from the
exposed skin-face, neck and hands
and about per cent from the hair.
Through the ordinary range of room
temperatures, Mr.. Aldrich points out,
there is very little change, if any, in
the basal metabolism, or heat produc-
ton, of the body itself. But with
radiation varying directly with the
temperatures of surrounding objects, a
very considerable readjustment, per-
haps in the form of water vapor loss
from the body, must take place to
compensate for a radiation decrease.
Other ways of getting rid of heat
are by the warming in inspired air,
warming of food, warming of i'm
mediately contiguous surfaces by
convection.
John j. Nicholson, postman, who
was awarded the D. c. M. medal during
the World War, was recently sentenced
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