The times. [volume] (Richmond, Va.) 1890-1903, 1891-10-11
The Power Required by Birds in Flying.

| Every living creature bird or insect. which
| has been able 10 raise itself from the earth
aud 10 propel itself through the air has a
| body many hundred times heavier than the
| same volume of air. and is endowed with the
| power OF exerting great mechanical force in
| proportion 10 its weight. Ii IS the expending
| of this physical force upon tho surrounding
| air that enables 1t 10 Hy. But tho actual force
| required by bird. in their flight has until re-
Gently been largely matter of con ecture
Many unsatisfactory attempts have been made
with thermometers attached 10 the bird itself
to measure the force OF its muscles but very
little of value has been accomplished IN this
direction. Mathematlclans without number
have invented formule and discussed the
question Of flight. but the most remarkable
feature has been the difference In the results
arrived ut. Many years ago matheInati-
clan IN France wrote "a treatise III which lie
proved that the common goose in flying
exerted q force equal to 100 horse power;
another proved that 1t was only 90 horse
power, and he was followed by still
another. who proved very much TO his own
satisfaction that it was only 10 horse-power
Later on others have written to prove that
goose expends only about / horsepower in
flying At the present time however, many
mathematicians can 10 found who are ready
to prove that only one-tenth of a horsepower
is exertcd by goose. | do not know on what
basis the earlier writers camo to their conclu-
sions. Those who proved the flight of goose
about horsepower in energy have figured it
on tue following basis. Suppose a goose TO
weigh II pounds. the wing surface being only
slightly over three square feet-the W ngs
alone being the only supporting power while
flying. Such goose would fall through the
mir. provided 1t made no motion with its
wings at the rate of about twenty-six miles
per hour, or say 1900 feet per minute. They
claim that tho goose III flying must therefore
perform work which is equal to raising his
AHs Fiat frftfa s.. -
would tall If 1t made no motion with its
wings. 1t is quite true If plane having
surface Of three square feet should be loaded
with twelve pounds that it would fall
through tho air at tho rate of 1900 feet
per minute. and if mir was propelled by me-
chanicnl energy against the bolt IN side of
this plane with sufficient force to hold 1t in
equilibrium and prevent ii from falling, the
energy required to propel this column of air
would be equal to lifting II pounds $500 feet
per minute The conventional unit of energy
in England and America is pound raised
pounds I 1890 AS the energy III foot
pounds, (which would bs 1860 foot
pounds in minute Of time. Now
as II requires SO 600 foot pounds for / horse
power they claim that 1t follows that IL
pound goose flying excrts .s3 horsepower.
This. however. is wido OF the truth In nv
experiments have found that tho advantages
arising FROM moving forward on 30 new air.
the inertia of which has not been disturbed.
would reduce the energy required to less than
one-tenth part OF this bccAuse the air underline
wings would not yield on-tonth part as much
If the goose wero moving forward at high
velocity. as II would If the goose remained ia
the same position and tapped It's wings with
sufficient energy TO sustain itself in tho air
without moving itself at all Tho goose
would. therefore. exert no moro than 0s3
horse power which 10 rather more thnn hall
a M N IL A. a.
to the horse -power.-Hiram S. Maxim, III the
Century for October.