The Morristown gazette. [volume] (Morristown, Tenn.) 1867-1920, 1881-05-25
Speed at which Wings Are Driven.

! The speed at which some wings are
driven is enormous. It is occasionally
! so great as to cause the piniOns to emit o
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
greatly resembles that produced by the
contact Of steel with the rapidly revolY-
ing stone of the knife grinder It has
| been estimated that the common fly
moves its wings $50 times per second, 4.
e., 10, 800 times per minute, and that the
butterfly moves its wings nine times per
second, or $40 times per minute. These
movements represent an incredibly high
speed, even at the root of the vii gs; 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 indi-
Gated, the speed of the tips Of the wings
increases in proportion as the tips are
removed from the axis of rotation, and
in proportion as the wings are long. This
is explained on a principle well under
stood IN mechanics. If a rod or wing
hinged at one point be made to vibrate,
the free end of the rod OF wing always
passes through o very much greater
space in a given time than the part
nearer the root of the wing. The pro-
gressive increase in the speed Of the
wings, in proportion as the wings be-
come larger, explains why the wings of
bats and birds are not driven at the eX-
travagant 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 small bats
and birds. That the wing is driven more
slowly in proportion to its length is
proved by experiment, and by observing
the fight of large and small birds of the
same genus. Thus, large gulls flap their
wings much more slowly than small
gulls; the confguration and relative size
of the wings to the body being the same
in both. This is hopeful feature in the
construction of flying as there
car be no debut that comparatively very
slo.9 movements Will suffice for driving
the long powerful wings required to ele-
vate and propel fying-machines The
speed of the wing is in part regulated by
the amplitude of the wing. Thus if the
wing be broad as well as long, the beats !
are necessarily reduced in frequency.
LIS 10 CO SDGC1dIlN IIIS O1 JllC LCIOlE,
which Is one of the most picturesque |
and at the same time one of the slowest |
flying birds we have. [ have timed the /
heron on several occasions, and find that !
in ordinary fight its wings make exactly |
sixty up and sixty down strokes, 3. e., I
100 beats per minute. In the ptero- /
dactyl, the great extinct Saurian, the /
wing was enormously elongated, and in /
g.,
50 to 60 beats of the wing per minute I
5ufficed for fight Fifty or sixty pulsa- /
ions of the wing per minute do not in
7oIve much wear and tear of the working
parts, and I am strongly of opinion that
artificial flight, if once achieved, will
become a comparatively safe means of
ocomotion as far as the machinery re-
Iuired is concerned. d.-FFaSer'S 1fagG-
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