, How Three Little Canals in Each
t
of Our Ears Keep Us Balanced
and Cause Airmen to Fall by
Making Them Believe They Are
Still Moving in a Certain. Direction
When Really They Are Not
THE mystery of many tragic accidents
to aviators resulting from inexplic
able failure of the flying men to
control their machines at critical mo
ments has now been cleared up by medi
cal science.
On each side of our heads, within the
middle ear. ck>selv connected with the
apparatus of hearing, there is a curious
little series of three hollow loops or
membranes. These are called the semi
circular canals because of their shape and
also because they are filled with liquid.
In these canals is our sense of balance.
On them depends our ability to keep erect
or to sway against external movements
and to transmit the sensation of balance
or our direction in space to our brains
It is through the functioning of these
canals that we are able, for instance, to
"brace ourselves" when a train in which
we are standing strikes a curve, for with
.out them we would have no sensation of
being |t an uncomfortable angle.
The ^emi-circular canals are, in fact, the
spirit levels of the body, and it is by the
impressions they send to the brain that
the motor centres send instructions to the
proper groups of muscles to keep the body
in proper Equilibrium against the force of
gravity.
It is the proper functioning of these
spirit levels in the aviator's ears that en
ables him to control the delicately bal
anced machine in which he flies and the
conduct of which is so dependent upon the
delicacy and trneness of perception of its
changes in angle by its driver.
V
Hew tn Aeroplane Make* u "Nose Dive," Illustrating
the Abnormal Positions of the Aviator During the
Process, W hich Are Registered by the Semi
Circular Canals in the Aviator's Ears, and
Whose Safety Depends Solely Upon
Their Accurate Functioning.
?lo
When the spirit levels of the semi-cir
cular canals fail to respond promptly or
are misled into thinking?if it can be
said that organs really think, and some
scientists believe that they do?that the ?
flying machine has a movement or an
angle different from what it really has that
disaster occurs to the pilot. How is this
centre of our sense of Ifalance misled?
That question is answered by Dr. Lewis
Fisher, major, and Dr. H W. Lyman, cap
tain in the Medical Corps of the United
States army. Both of these scientists
have long been on duty at the great avia
tion camp at Mineola, Long Island, and
have had the best opportunity for obser
vation possible. They give the results of
these observations in the Journal of the
American Medical Association. '
The semi-cirdular canals are filled with
a liquid called endolymph, and in this
endolymph float a great number of almost
microscopically small hard bodies called
otoliths, literally ear stones. The canals
and the bulb to which they are attached
are close beside, indeed, almost a part of,
the actual centre of hearing in the ear,
which is a shell-like body called the coch
lea. The two together are termed the
bony labyrinth of the ear* There is one,
of course, in each ear. But although so
close together the functions of the semi
circular canals and the cochlea are en
tirely separate.
The reactions to sound of the cochlea
are carried through the auditory nerve to
the brain, but the reactions to gravitation
or direction in space of the body possess
ing It is not carried through this same
nerve by the canals. Science, indeed, has
not yet discovered just how the impres
sions do go- from the canals to the brain,
but however transmitted they are trans
mitted very thoroughly. Vertigo, with its
nausea and other unpleasant symptoms, is
caused by the functioning of these canals
probably more than by any other factor.
It appears that when the head is turned
or bent a movement is set up in the liquid
within the semi-circular canals which is
transmitted to the otoliths. It is supposed
that these otoliths swinging against the
sides of the canals touch upon the nerves
there and communicate the sensation of
movement through them to the brain.
When one is whirled about suddenly and
violently or for any. length of time the
movements of the lymph and otoliths con
tinue in the ears in the same direction in
which they have been proceeding. When
this happens we have exactly the same
sensation of movement that we have been
experiencing, although at the time all
movement has ceased. This is why after
a long rock in a rocking chair one gets up
and feels as though she were still rocking.
It also explains why people who have had
long, rough sea voyages for some consid
erable time afterward experience the sen
sation of walking on an unstable earth.
All this is due to the fact that the liquid
and little stones in the canals have not
yet quieted down.
And in the violent movements which
aviators must experience, especially in
"stunt flying," this is doubly true.
Here, say Drs. Fisher and
Lyman, is ihe explanation of
the mysterious falls. The air
pilot is moving at a terrific
speed; fractions of minutes,
. and even fractions of sec
The Three Angle* of Movement Through Which the Head of the Aviator
Paste*. First, the Frontal Motion; Second, the Horizontal;
Third, the Sagittal, or from Back to Front Movement.
The Semi-Circular Canals in
Which Rests Our Balancing
Sense. A Is the Superior, B
the Posterior and C the Hori
zontal Loop. Each of These
and Their Bulb, D, Is Filled
With a Fluid and Almost
Microscopic Hard Particles
That Give the Brain Percep
tion of the Body's Angle.
onds, are as important
to him as hours are to
people walking on solid
earth. Coming out of
some violent evolution the
movement in the s-pirlt
levels persists, his brain
becomes confused, he mis
judges angles and posi
tion, grasps the wrong
control and crashes to
earfh and death.
By vizualizing the posi
tion of the pilot as he is
whirled in the various
stunt evolutions, it was
found that by reproducing
a similar whirling in a chair balanced on
subjective effects of the actual stunt.
Established facts or principles, the doc
tors wrote, are the following:
"1. In each ear we have three semicircu
lar tubes, or canals, containing fluid, so
placed that they are at right angles with
one another. Because of this arrangement,
no change of position of the individual is
possible without producing some move
ment of fluid in one or more of the canals.
Movement of the fluid in these canals.
Bends messages to the brain, which are
there interpreted as body movement.
Hence, the ears constitute the motion
sensing organs of the body.
"2. When an individual is whirled, be it
Diagram Showing How the Laboratory Chair Is Used to
Simulate the Movements of What Is Known
Among Aviators as the "Tight Spiral."
The absence of such an essent:al organ as
a motion-perceiving apparatus is too great
a handicap to the man travelling in an
'air medium' to Justify him even in think
ing for a moment that he could dispense
with it for the sole benefit of vertigo im
munity, especially since the normal indi
vidual can acquire such an immunity with
out much difficulty.
"There are three cardinal angles or po
sitions or vertigo, it seems?horizontal,
frontal and sagittal. These angles are il
lustrated by the diagram of the three heads
at the bottom of this page.
"The greatest usefulness of the knowl
edge that 'stunting' is an ear problem lies
in the fact that the flier may be educated
to disregard the vertigo effects of his
in-the laboratory or in an aeroplane, there a'stunts' in the laboratory, instead of among
is produced a circulation of this fluid in
certain definite canals and planes. Now, if
the turning is suddenly altered or stopped,
or if the aeroplane comes out of a rotating
manoeuvre, the fluid in the canals con
tinues to move in its former plane by sheer
force of its momentum. The circulation of
the fluid by momentum is interpreted by
the brain as body movement; but not being
in accordance with fact, the body having
ceased to revolve, it constitutes vertigo or
dizziness, and is disturbing to the indi
vidual.
"Labyrinthine vertigo, therefore, is a
false sensation of motion similar to the
visual illusion of motion observed when
one is watching a moving train from the
window of a stationary coach, both being
unavoidable phenomena of normal special
sense mechanisms which, however, the
subject easily learns to disregard.
"One must not fall into the error, how
ever, of thinking that the lack of a normal
ear mechanism would be advantageous to
the flier, because of the immunity to ver
tigo which this condition would confer.
tke clouds, and without danger acquire a
tolerance to evolutions to a degree impos
sible in the air. This can be accomplished
by the use of an otologic apparatus known
as the 'orientator.' In its construction it
is like the cockpit of an aeroplane sus
pended in-concentric rings, after the man
ner of a ship's compass. The movements
?or changes of position?which are pos
sible in all directions except actual for
ward progression, are governed by the in
dividual seated in the machine, using a
set of controls resembling those of an
aeroplane."
The Mechanism of "the Loop," Showing
the Various S gittal Positions of the
Head the Flyer Assumes.
The Spinning Nose Dive, in Which the
Aviator's Head Is Whirled Both
Vertical and Horizontally.
"?<
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Copjrifciit, l?ia, by Star Company Ureut Britain Hlghts Reserv.-d