The true northerner. [volume] (Paw Paw, Mich.) 1855-1920, 1880-09-17
HOW Birds Fly.

You will find, if you carefully examine
n bird s wing, that all the bones and mus
cles are placed along the front edge,
which is thus made very stiff and strong.
The quill feathers are fastened III such
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 n gas, it has "a tendency to
slide out from under the wing when this
is driven downward, and of course 1t VIII
do this at the point where it can escape
most easily. Since the front edge OF
the wing is stiff and strong, 1t retains
its hollow shape, and prevents the ar
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, SO the air
makes its escape there, and slides out
backward. The weight of the bird is all
the time pulling it down toward the earth;
so at the same time the air slides out up
ward and backward, past the bent edge
of the wing, the wing itself, and the bird
slides forward and downward off from the
confined air. 1t is really its weight
which causes it to do this, SO that the
statement that bird flies by its own
weight is strikingly true.
This is true, also, of insects and bats.
They all have wings with stiff front edges
and flexible hind 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 it flies by falling back toward the
earth and sliding forward at the same
time At the end of each stroke Of its
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 hight and moves forward IN
straight line.
IL you watch the fight Of those birds
which flap their wings slowly, such as
the woodpecker, you can see them rise
and fall, and will have no trouble Ill see
ing that their path is not really a straight
line, but is made up of curves; although
most birds flap their wings SO rapidly
that they have no time to fall through
space great enough to be seen. Birds
also make use of the wind to aid them III
fight, and by holding their wings in
clined like kite, SO that the wind shall
slide out under them, they can sail great
distances without tapping their wings
at all. They are supported, as paper
kite is, by the wind, which is continually
pushing against their wings, and sliding
out backward and downward, thus lifting
or holding up the bird, and at the same
time driving it forward.
The birds are not compelled toface the
wind while they are sailing, but by
changing the position of the wings lit
tie they can go in whatever direction
they wish, much as boy changes his
direction in skating by leaning a little to
one side or the other. Some birds are
very skillful at this kind of sailing, and
can even remain stationary i'll the air for
some minutes when there is strong
wind; and they do this without Tapping
their wings at ALL 1t is a difficult thing
to do, and no birds except the most skill
full 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 fight.