The Kenosha telegraph. [volume] (Kenosha, Wis.) 1860-1888, 1883-01-19
How the Senses are Fooled.

1mmerse the forefnger of one hand
in water at 104 degrees Fahrenheit, and
then plunge the whole of the other hand
into the water with temperature of 102
degrees Fahrenheit. The latter, although
two degrees cooler, viii be judged to be
the warmer of the two, from which it
appears that the intensity of the sensa-
ton of temperature depends not only
more upon the relative degree of heat to
which the parts are exposed, but also
upon the extent of surface over which it
is applied. From this cause a bath which
is not uncomfortably warm, when a few
fingers are dipped into it, appears scald-
ing hot when the whole body is inn
mersed. The sense of temperature is,
likewise, entirely at fault when required
to determine which is the warmer of two
substances, say piece of iron and piece
of wood, for if they both have the same
temperature, the iron will feel the hotter
of the two, because of its being a so much
better conductor. A slight difference of
temperature, however, between two sub
stances of like nature is easily discerned,
and we may here describe a simple
but MISUNDERSTANDING trick which is
founded on the fact.
The performer having placed his hat
behind him, requests the people pres
ent to place in it three or four pennies.
He shakes it up behind him, and then
asks some person to take out penny
and closely examine it. He has then to
pass it to the others for examination,
the last one pitching it back into the
hat again. The pennies are then re-
shaken up, and the performer now,
placing one hand behind him. picks out
the penny which has been examined, al
though throughout the whole operation
he has never seen it. When the expert
ment has been done some two or three
times successfully, all sorts of unlikely
suggestions are made as to the way in
which the feat has been performed, but
very seldom the right one, which is ex-
ceeding simple. The people. in hand
ling the penny which was selected from
the others, make it warm. 1t is, there
fore, easy to pick it out from the others
when it has been pitched into the hat
again. This sufficiently demonstrates
the fact that at ordinary temperature
the sense of temperature as localized in
the fingers is sufficiently sensitive to
discriminate between several pieces of
metal so as to say which is the warmest.
But for the extremes of hot and cold,
touch is thoroughly deceived, piece of
frozen mercury giving burning sensa-
ton like red hot bar of metal. The
touch which attains to such perfection
in persons afflicted with blindness is
readily deceived This is shown forcibly
by the experiment of Aristotle. Cross
the index and middle fingers and run
them over marble placed on table
with the eyes shut Under such circum
stances one has difficulty in avoiding the
belief that he is dealing with two
marbles instead of one. The idea of
roundness which has been obtained by
complex judgment, founded on the
coalescence of several sensations, is here
appealed to, but the usual conditions
being reversed, we draw a wrong con-
clusion. The sense of taste may be
likewise COMPOUNDED by altering the con-
ditions under which the gustatory
operation is always carried on. Thus,
if the nostrils be held firmly, it is i'm
possible to distinguish between applying
an onion or an apple to the tongue.