The Dallas daily herald. [volume] (Dallas, Tex.) 1873-1887, 1886-10-06
THE NAVIGATION OF THE AIR.
Ono Mode OF Travel that Battles IIu-
man Ingenuity-Ihc Flight
of Hirds.

has been able To accomplish wonders,
says The PittSJurgh Dispatch.
We can not go to the planets 10 view
them, so by our telescopes we bring the
planets to us. With microscopes we
observe the daily life OF the most minute
organisms. The telegraph and tele-
phone enable us to converse with friends
who are miles away Our application
of the power of steam takes us TO dis
tant places in days time which in
former years would have required
months. but there is yet remaining one
mode of travel which seems to battle
human ingenuity That is the naviga-
ton of the air-a problem which will
never be solved until some moving
power be discovered which is very much
lighter than any we now know, and
machinery employed which is in ac-
cordance with the natural laws which
enable birds to fly with such ease.
1t is perfectly useless to attempt to
navigate the air by means of balloons.
A balloon rises because it is lighter than
air and floats upon or in it, but for
this reason it is wholly at the mercy of
the air current; one might as well ex-
pect TO control the motions of thistle
blow. There is general idea that
birds sustain themselves in the air
largely on account of lightncss, and
on account of their hollow bones being
filled with heated air, but it is quite
manifest that if they were rs light or
lighter than the mir they could not
make any forward motion, as Ike the
thistle blow they would be carried
hithcr and thther by every breath of air.
One of the most potent factors in a
birds flight, therefore, is its weight.
The force OF gravita;ion works con-
slant influence upon the bird TO draw it
toward the earth, and the force of the
stroke of its wings must be enough,
and little more than enough to over
come this force of gravity. In so do
ing the weight of the body acts as a
fulcrum, or in other words, gil; $ it
something to push against, and help it,
when it has gained momentum, to sail
along without any effort, except that ex
pended in keeping the wings stretched.
The amount OF force used in flying
is very great, much more than is sup
posed. The constant beating of the air
necessary to keep the body from falling
to the ground is not all, the bird must
also be propelled forward. The muscu-
lar force expended by humming- birds
and other birds whose wings move
rapidly must be enormous. Anyone
who has watched a heron knows that
they move their wings slowly, and yet
they will find, to their surprise, that if
the wing-beats are counted they amount
to 120 to $50 strokes minute. A hum
mcr's wings move so fast that they can
not be seen, only blur at each side of
its body is noticeable, and the number
of beats per minute is uncomfortable
representing wonderful expenditure
of force and energy.
The duke OF Argyll in a very enter
tanning chapter entitled ''Contrivance a
Necessity" speaks of birds wings
and the mechanism of flight in these
words: mo more beautiful example
can be found, even in the wide domain
of animal mechanics. none of which
we can trace more clearly, too, the
mode and method in which laws, the
most vigorous and exact, are used as
the supple instruments of purpose.
The construction of the wing and
the BIRDS delicate and expert use of it
are u very interesting subject, and have
formed the basis of all attempts of
man to construct device for naviga-
ting the air
There are things about wing which
would he very hard to initiate in any
piece of machinery. In the first place
the wing must be of sufficient surface
and supplied with sufficient muscular
forces so that its strokes upon the ar
will be able to counteract the force OF
gravity drawing the body to the earth
but it would seem that the upward
stroke would neutralize this completely,
just rs If, in rowing boat the oar
should be kept in the water as it recov-
cred for fresh stroke. The wing
however, is so contrived that the mini
mum of resistance is encountered. The
feathers of the wing undcrlie each 9th
er so that during the downward beat
these feathers are forced to lie togeth
er, thereby preventing the air from
passing through. as the vane of one
feather lies against the shaft of the
next, but during the upper beat these
are all opened like so many valves, al
lowing free passage of the air and not
obstructing the wing.
Besides this the general shape of the
wing facilitates the motion. All wings
are concave below and rounding above.
During the downward blow the air is
collected and offers resistance. and dur
ing the reverse the air flows off the up
per side. very well illustrated by any
one who is in strong wind with an
umbrella. The wind will roll of the