The Wichita daily eagle., 1894-03-02
A CHAPTER ON AERoNAuTlcs.
The Work of the Wind In tho Flight {
Birds.

A CHAPTER ON AERONAUTlCS
The Work Of the Wind In tho Flight Of
Birds.
It has long been observed that GER
tain species of birds maintain them
selves indefinitely in the air by 'ssoar-
ing" without any tapping of the wing,
or any motion other than a slight
rocking of the body: and this. although
the body in question is many hundred
times denser than the air in which it
seems to float with an undulatiug
movement, as on the waves Of an in
visible stream.
No satisfactory mechanical explana-
tion of this anomaly has been given,
and none would be offered in this
connection by the writer were he not
satisfied that it involves much more
than an ornithological problem. and
that it points to novel conclusions OF
mechanical and utilitarian Importance.
They are paradoxical at first sight,
since they imply that under certain
specified conditions very heavy bodies
entirely detached from the earth, inn
mersed in and free to move in the air,
can be sustained there indefinitely
without any expenditure OF energy
from within.
These bodies NAV be entirely OF
mechanical construction, as will be
seen later, but for the present we will
continue to consider the character OF
the invisible support of the soaring
hi rH nd TO ct, <c y>o0finnc fhnnrh
only as pregnant instance offered by
nature to show thata rational solution
of the mechanical problem is possible.
Recurring, then, to the illustration
referred to in the first paragraph, we,
may observe that the flow of an ordi-
nary river would afford no explana-
tion of the fact that nearly inert crea-
lures, while free to move, although
greatly denser than the f]aid, vet float
upon it; which is what we actually be.
hold in the @rial stream, since the
writer, like others, has satisfied him.
self by repeated observation that the
soaring vultures and other birds ap-
pear as if sustained by some invisible
support in the stream OF air. sometimes
for at least considerable traction OF
an hour. It is frequently suggested
by those who know these facts only
from books that there must be some
quivering of the wings, so rapid as to
escape observation. Those who dc
know them from observation are aware
that it is absolutely certain that moth
ing of the kind takes place, and that
the birds sustain themselves on pinions
which are quite rigid and motionless,
except for a rocking or balancing
movement, involving little energy.
The writer desires to acknowledge
his Indebtedness to that most consci
entious observer, NJ Mouillard, who
has described these actions of the soar
ing birds with Incompatible vividness
and minuteness, and who asserts that
they under certain circumstances, with.
out Tapping their wings rise and actu.
ally advance against the wind.
To the writer, who has himself been
attracted from his earliest years to the
mystery which has surrounded this
action of the soaring bird, it has beer
a subject of continual surprise that il
has attracted so little attention from
physicists. That nearly inert bodies,
weighing from five to ten and ever
more pounds, and many hundred times
denser than the air, should be visibly
suspended in it above our heads, some
times for hours at time, and without
falling-this, it might seem, is, with
out misuse of language, to be called
physical miracle; and yet the fact that
those whose province it is to investi
gate nature have hitherto seldom
thought it deserving attention is per
haps the greater wonder.
This Indifference may be in some
measure explained by the fact that the
largest and best soarers are of the vui
ture kind, and that their most striking
evolutions are not to be seen in those
regions of the northern temperate zone
where the majority of those whose
training fits them to study the subject
are found. Even in Washington. how.
ever, where the writer at present re.
sides, scores OF great birds may be seer
at times in the air together gliding
with and against the wind, and ascend.
ing higher at pleasure on nearly mo-
tionless wings. ''Those who have not
seen it," says NJ. Mouillard, when
they are told of this ascension without
ready to say: But there must have
been movements, though you did not
see them and in fact" he adds, ''the
casual witness of single instance, OF
reflection himself feels almost doubt
as to the evidence of his senses when
they testify to things SO extraordin.
ary."
Quite agreeing with this the writer
will not attempt any general descrip
tion of his own observations; but as an
illustration of what can sometimes be
seen, will give single one, to whose
exactness he can personally witness.
The common turkey buzzard (Cathartes
AURA is so plenty around the environs
of Washington that there is rarely
time when some of them may not be
seen in the sky, gliding in curves over
some attractive point or (rnore rarely
moving in nearly straight lines on rigid
wings, if there be moderate wind
On the only occasion when the motion
of one near at hand could be studied in
a very high wind, the author was
crossing the long Aqueduct bridge over
the Potomac in an unusually violent
November gale, the velocity of the wind
being proba bly, over thirty-fve miles
an hour About one-third of the dis
tance from the right bank of the
river. and Immediately over the right