The daily gazette. [volume] (Wilmington, Del.) 1874-1883, 1881-04-21
THE SPEED OF THE WING.
SOME INTERESTING FACTS ABOUT THE


SOME INTERESTING FACTS ABOUT THE
FLIGHT OF BIRDS.
A writer in Frdzer's Magazine says
The speed at which some wings are
driven is enormous. 1t IS occasionally
so great as to cause the pinions to emit a
drumming sound. To this source the
buzz Of the fly, the drone of the bee, and
the boom OF the beetle are TO be referred.
When grouse, partridge, or pheasant
suddenly springs into the air, the sound
produced by the whirring Of its wings
great resembles that produced by the
contact of steel with the rapidly-revolv-
ing stone of the knife-grinder. 1t has
been estimated that the common hy
moves its wings $50 times per second, l..
g., 800 times per minute, and that the
butterfly moves is wings nine times per
second, or $40 times per minute. These
movements represent an incredibly high
speed even at the roots Of the wings; but
the speed is enormously increased at the
tips of the wings, from the fact that the
tips rotate upon the roots as centres. In
reality, and as has been already indica-
ted, The speed of the tips Of the wings
increases In proportion as the tips are
removed from the axes of rotation, and
in proportion as the wings are long. This
ia explained on principal well under
stood in mechanics.
Ifa rod or wing hinged at one point
b. made to vibrste, the free end OF the
rod or wing always passes through
much greater space in a given time than
the part nearer the root of the wing.
The progressive increase in the speed of
the wings, in proportion as the wings
become larger, explains why the wings
of bats and birds are not driven at the
extravagant speed of insect wings, and
how the large and long wings of large
bats and birds are driven more leisurely
than the small and short wings of large
and small bats and birds. That the
wing is driven more slowly in proper
ton to its length is proved by expert
ment, and by observing the fight OF
sarge and small birds of tie same genus
Thus, large gulls Zap their wings much
more slowly than small gulls the con-
fguratloD and relative size of wings to
the body being the same In both. This
Is hopeful feature in the construction
Of flying machines, as there car be no
doubt that comparatively slow move
ments will suffice for driving the long,
powerful wings required to elevate and
propsl flying machines.
The speed of the wing is in part
regulated by the amplitude Of the
wing. Thus If the wing be broad as
we'll as long, the beats are necessarily
reduced in frequency. This is especial
ly true of the heron, which is one of
the most picturesque and at the same
time one of the slowest birds we have.
l have timed the heron on several occa-
sions, and find that in ordinary flight
it's wings make exactly sixty up and
sixty down strokes--i. O., 1870 beats
per minute. In the pterodactyl, the
great extinct Saurian, the wing was
enormously elongated, and in this par
ticular instance probably from 90 to
go beats of the wing per minute suf.
feed for flight. Fifty or sixty pulsa-
tions of the wing per minute do not
involve much wear and tear of the
working parts, and ] am strongly of
the opinion that artificial flight, if once
achieved, will become comparatively
safe means of locomotion, as far as
the machinery required is concerned.