Freeland tribune. (Freeland, Pa.) 1888-1921, 1900-05-24
THE FACULTY OF FLIGHT
A PROBLEM THAT MAY BE SOLVED
BY THE BIRD-ANATOMIST.
There May BE Principle, Not Yet Gnessed
at, That Will Explain All the Mystery
OF fBird-FliEht-TheM Muscular Power of

The problem of bird-hight has its
humors and its absurdities. Recently
there has been revival of the gas
eous theory to account for the appar-
entity impossible, yet every day-vis-
ible, performances of the hawks and
buzzards, the swifts and indeed all of
the best flyers. 1t is said that birds
have pneumatic system, in addition
to the osseous, muscular, vascular,
nervous and other systems common to
all higher animals; and that by the
functioning of this particular system
they render themselves so buoyant
that their alar operations are compar-
atively easy, requiring far less muscu.
lar exertion and nervous expense than
would appear to be necessary.
This theory seems to me pre-
posterous, being based in flat con-
tradiction of an axiom of natural
philosophy. A balloon, when collapsed,
will not rise in the air; but when
expanded with gas lighter than our
atmosphere it scars. The same prin-
ciple causes hull to float on water
when solid of the same size would
sink plump to the bottom. If the
bird has a system of pneumatic cavi-
ties, the birds body is at its lightest
when those cavities are absolutely
empty; for no gas is lighter than
vacuum. Then clearly the only
method by which the bird can increase
its buoyancy in this connection is by
expanding its substance, and at the
same time filling the spaces with O
gas extremely light and yet able to
resist the increased pressure of the
external air. But does bird expand
its bones, or even its softer parts, to
any practical extent while flying?
No theorist claims that it does. If
such expansion were possible the
only service gas could perform
would be to resist the atmos-
pheric pressure; for, rs have said,
the bird would be lighter without the
gas than with it. No substance is
lighter than nothing!
1t is perfectly manageable problem
to calculate just how much a buzzard
would have to expand the "cavities of
its pneumatic system" in order to in
crease the buoyancy of its body n
given number of ounces. But sup
posing the bird can Mt will expel from
its bone-cavities aud other pneumatic
reservoirs all gaseous contents, there
would not be an appreciable lessening
of weight in the problem of flight.
In fact, if buzzard could at will dis
card its entire abdominal viscera, the
loss of substance would not be sutfi-
cient to make any great change in our
problem; for the wild goose is twice
as heavy in the body as turkey
vulture, and just as good a flyer, with
out any advantage in wing force. The
difference in sailing ability in favor OF
the vulture is easily accounted for on
the score of natural bodily lightness
but this comparison does not in any
way assist in settling the main ques :
ton. OF course if two birds have
equal wing force and greatly unequal
bodily weight, the heavier will have
to work the harder in flying. Still,
under the most favorable co-ordina-
ton of weight and wing power IN a
bird, the problem of flight is far from
solution.
1t is easy to catch buzzard, vul-
ture or q goose and accurately meas
ure the muscular force of its wings.
1t has been done. This force has not
been found very remarkable. A boy
twelve years old can hold both wings
of a twenty pound goose in one hand
without great exertion. The wing
muscles are strong, but not marvel
ously strong; about equal to those OF
a strong mans thumb. Well, very
strong man can lift his own weight
with his two thumbs; wherefore it
should be easy enough for goose to
lift twenty pounds with the same
muscular power. Here, however,
comes in the the immense counter.
leverage Of the birds long wings as O
troublesome element of our calcula'
ton. Let strong man take in his
hand van, the full size of vulture's
wing, and attempt to sweep it swiftly
through the air; the realization oi
what the bird overcomes with such
apparent ease and with such marvellous
grace will Immediately arrive. 1t may
be said that in any event the vulture
has but to sustain the weight of its
own body; but remember that this
must be with outstretched wings
Were the wings mere thumbs and tht
extreme leverage only three or foul
inches, all would be well; but the air
pressure on the entire wing is at las
borne by the muscles where they pas!
the wing joint, next to the body, and
the strain is kept up for many hour!
without moments rest. The strong
est mans arms could not bear it fo
two hours, as experiment would easil.
disclose.
The flight problem, therefore, sug
gests deeper examination into bird
anatomy than has yet been made. Th
whole physiological structure must b.
restudied with view to accounting 70
the immense nervous resources of th
avian physique. Long continued
muscular exertion uses up nervou
force, with a corresponding exhaus
ton of heart-power, lung-power an'
will-nowar Are birds NOT subiect I,