The Elk County advocate. [volume] (Ridgway, Pa.) 1868-1883, 1878-09-05
How Birds FIy.

You will find, if you carefully exam
inc birds wing, that all the bones and
muscles are placed along the front edge,
which is thus made very stiff and strong.
The quill feathers are fastened in such a
way that they point backward, so that
the hind edge of the wing is not stiff
like the front edge, but is flexible and
bends at the least touch. AS the air is
not solid, but a gas, it has tendency
to slide out from under the wings when
this is driven downward, and, of course,
it will do this at the point where it can
escape most easily. Since the front
edge OF the wing is stiff and strong, it
retains its hollow shape, and prevents
the air from sliding out in this direction,
but the pressure Of the air is enough to
bend up the thin, flexible ends Of the
feathers at the hinder border of the
wing, 80 the air makes it's escape there,
and slides out backward and upward.
The weight of the bird is all the time
pulling it down toward the earth; so, at
the same time that the air slides out
upward and backward past the bent
edge OF the wing, the wing itself, and
with it the bird, slides forward and
downward off from the confined air. It
is really its weight which causes it to do
this, 80 that the statement that a bird
flies by its own weight is strictly true.
This is true, also, of insects and bats.
They all have wings with stiff front
edges which bend and allow the air to
pass out, SO that flying is nothing but
sliding down a hill made of air. A bird
rises by Tapping its wings, and 1t flies
by falling back toward the earth and
sliding forward at the same time, At
the end of each stroke of it's wings it
has raised itself enough to make up for
the distance it has fallen since the last
stroke, and accordingly it stays at the
same height and moves forward in a
seemingly straight line. But if you
watch the flight of those birds which flap
their wings slowly, such as the wood
pecker, you can see them rise and fall,
and will have no trouble in seeing that
their path is not really straight line,
but is made up of curves; although most
birds flap their wings so rapidly that
they have no time to fall through a
space great enough to be seen. Birds
also make use of the wind to aid them in
flight, and by holding their wings in
cllned like kite, 80 that the wind shall
slide out under them, they can sail great
distances without Tapping their wings at
all. They are supported, as parer kite
is, by the wind, which is continually
pushing against their wings, and sliding
out backward and downward, thus lift.
ing or holding up the bird, and at the
same time driving it forward. The birds
are not compelled to face the wind while
they are sailing, but by changing the
position of the wings little they can 90
in whatever direction they wish, much
as boy changes his direction in skating
by leaning little to one side or the
other. Some birds are very skillful at
this kind of sailing, and can even re-
main stationary in the air for some min
utes when there is strong wind; and
they do this without tapping their
wings at all. 1t is difficult thing to do,
and no birds except the most skillfui
flyers can manage it. Some hawks can
do it, and gulls and terms may often be
seen practicing it when gale of wind is
blowing, and they seem to take great
delight =. in their power Of aight.-%.