The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1902-09-25
THE SECRET OF BIRD SOARING
A Naturalist Who Thinks He Has
Found 1t Inside the Quills.
lChambers' Journal.)


What is the motive power of quies-
cent bird that moves it through air re-
sistance and keeps its heavy body from
falling? We are absolutely baffied when
confronted with the problem OF a soar
ing bird.
IL does not move its wings when Il
has once got we'll started; It's moving
parts seem 10 be OF use merely TO get
ii OF some unknown dead CENTER IL has
infinite capacity for taking advantage
OF balance; and all this is done while
violating every known mechanical law,
holding up heavy body in the air and
overcoming strong atmospheric resist
ance at a rapid rate without discover
able expenditure of energy.
Yet weight is absolutely necessary
for flight, and the relative area of wing
expanse diminishes as the weight of the
bird increases. For example, a gnat,
which possesses a very light, fairy-hke
body. has about eleven times the wing
area OF a swallow IN proportion TO the
weight OF each.
/ have been trying TO discover the
exact structure of a birds surfaces
which enables il TO get the soaring
force from the air pressure under its
wings for the past fifteen years. The
task seemed hopeless until accident set
tied the case. had located in the foot
hills OF the Flat Top mountains of
Colorado, In the dry air OF that region,
TO prosecute my task, where the yell
low-tailed hawks that were admirable
soaring birds were abundant.
A precipitous cliff LOCO feet high was
near, from which l floated all sorts of
surfaces, and year after year the quest
went on. A furious forest fire had filed
the air with smoke and ashes and the
OdOr of burning wood was in evidence
for months.
l had killed a large hawk and was
examining its feathers when a stain
was detected on the sides of the quill,
between the spicules, that was not be
fore seen. A small magnifier gave 1t
the appearance Of discolorations about
the throat OF dust exhaust in a plan
ing mill.
A microscope was at once procured,
with an outfit of detectives from six
~ 10 100 diameters, and in an hours
time l knew more about bird flights
than twenty-five years of study had
given me.
The discolorations extended along
each spicule between the plates. The |
doWny flaments filling the double wall
structure of the wings were stained In |
the same unusual manner. This stain, /
when scraped off and examined, resem- |
bled SCOT from stovepipe, showing !
that the air had been going through /
the wing in an ineessant stream, car
rying the smoke and carbon particles |
of the IRE with it. / had been the /
slave of preconceived ideas.
And this brings me to the device that /
scars the bird. What Is a feather? 1t /
is an air engine. and the bird surfaces |
are made of them. They have been !
looked on as a light. flexible material I
for making an extended surface i'm
perVious 10 air that would readily fold ]
upon itself. and their exquisite meehan- !
zeal structure has been overlooked.
They consist of a quill and two vanes /
made up Of spicules. between which |
are the plates. The plates cross a /
channel about one-fortieth of an inch |
wide, made by the spicules. There are 1
about 1000 of them to the inch, being 1
innumerable, and they are
located at the outer surface, filling 4
about one-hfth part of the depth of the /
channel. They are about the twenty /
thOusandth part of an inch thick. as =.
nearly as an amateur with a micro [
scope could determine, so that nine
of the space of the
is open to the passage of air.
The mechanical service of the plates
is obvious. The curve impinges against
the air current through the feathers
and drives the bird to the front. Pres
sure produced by the normal factor of
weight is thus made to serve as the
motive power of flight.