San Antonio daily light. [volume] (San Antonio, Tex.) 1886-1907, 1891-10-20
BIRDS IN FLIGHT.
The Force They Use Figured DowT
TO Horse Power.

TO Horse Power.
Hiram S. Maxim in the Century.
Every living creature, bird or in
sect, which has been able to raise it.
self from the earth and to propel it.
self through the air has body many
times heavier than the same volume
of air, and is endowed with the power
of exerting great mechanical force in
proportion to its weight. 1t is the
expanding OF this physical force upon
the surrounding air that enables II
to fly. But the actual force required
by birds in their flight has until re-
Gently, been largely matter of con-
lecture. Many unsatisfactory attempts
have been made with thermometers
attached to the bird itself TO measure
the force fits muscles, but very little
of value has been accomplished in
this direction. Mathematcians with
out number have invented formulate
aud discussed the question of flight,
but the most remarkable feature has
been the difference in the results
arrived at. Many years ago mathe-
matician in France wrote a treatise in
which he proved that the common
goose in flying eXerted a force equal
to. 200 horse-pow er; another proved
that it was only fifty horse. power,
and he was followed by still another
who proved very much to his own
satisfaction that it was only ten horse
power. Later on others have written
tDprove that q goose eXpends only
about one horse power in flying. At
the present time, however, many
mathematicians can be found who
are ready to prove that only one tenth
of horse power is eXerted by goose.
do not know on what basis the ear
lier writer's came to their conclusions.
Those who proved the flight of
goose about one horsepower in enge-
ry haye figured it on the following
basis; Suppose goose to weigh Il
pounds the wings surface being only
little over three square feet-the
wings alone heiDg the only support.
Ing power while flying. Such goose
would TALL through the air, provided
it made no motion with it's wings, at
the rate Of about 26 miles per hour,
or say 2600 feet per minute. They
claim that the goose in flying must
therefore perform work which is
equal to raising his body 1900 feet per
minute, or as fast as it would fall if it
made no mntiOnG, with ito wings
II is quite true If plane having a
surface nt 3 square feet should he
loaded with II pounds that it would
ls.II ,uGUuSn LIO ar at rate Oh 23OO
feet per minute, and if air was pro-
PEELED by mechanical energy against
the bottom side of this plane with
sufficient force to hold it in equil.
ibrium and prevent it from falling the
energy required to propel this column
of air would be equal TO lifting II
pounds 2300 feet per minute. The
conventional unit of energy in Eng
land and America is | pound raised
one foot high; we should therefore,
have II pounds 1900 as the energy
i'm foot pounds, which would be 81,
COO foot pounds in one minute of time
Now as il requires SO 900 pounds for
one horse power, they claim that it
follows that l2-pOnnd goose flyiug
exerts Tx 300 divided by $4,000
making SO horse power. This, how
ever, is wide of the truth. In my OK
periments / have found that the ad-
Vartsges arising from moving forward
on to new air, the inertia of which
has pot been disturbed, would reduce
the energy required to less than one
tenth part of this, because the air I'M
dr. 'he wings would not yield one
tenth part as much if the goose were
moving forward at high velocity as
it would if the goose rem aimed in the
same position and tapped it's wings
with sufficient energy to sustain it
telf in the air without moving ahead
at all. The goose, would therefore,
exert no more than .0S3 horse power
which IS rather more than halt q
man power, and is at the rate of IA
5 pounds to the horsepower.