The times. [volume] (Washington [D.C.]) 1897-1901, 1901-01-27
AIR MACHINE FLIGHTS
Theories of an Experimental Based
on Bird Soarings.
Views of Prof. Langley, of the smith
sonian Institution, on Navigation
chanicai Power Exercised by the
Feathcred Tribe That Flaps Wings.

Pro1. :. Z. Langley OF tue 0hiASuSuh'''N
Institution, has been rather quiet lately
about his flying machine. but he has not
abandoned the idea of its practicabllity by
any means Like the late Mr.. Darwin he
is merely looking for missing link to
bind his theories together and make Of
them a palpable reality. Prof. Langley
bases his ideas regarding the possibility
of human flight upon the principles DEM
onstrated in the flight Of birds and rejects
utterly the notion of a navigable balloon
which is being developed at present in
Russia and France with more or less sue
cess.
As to the flight of birds Prof. Langley
says:
1T is generally known that birds sus-
tain themselves in the air in two distinct
ways: First, by the direct exercise OF me-
chanical power, as in large class of birds
that flap their wings. Although the exact
motions and power OF the wing have not
yet been studied exha ustively, there is
nothing in this method of support. con-
sidered as a mechanical contrivance in
apparent contradiction to known princi-
pies. Second another and important class
of birds, including the largest, can fly
without Tapping the wings and are able TO
glide over the landscape (sometimes from
horizon to horizon) on nearly motionless
pinions, in a manner and with an effect
which is not easily explained on known
mechanical principles, and which is in
striking contrast with the labored way of
other birds. This manner, which has new
er yet been completely accounted for, and
which is called soaring flight, is what
l would emphasize particularly in its i'm
nortaOra toward the sllbiect of artificial
aerial navigation.
I'm this latter case the bird is in some
way held up, as though by an invisible
hand, upon the thin and yielding air, on
which 1t seems TO float almost like ship.
although its specific gravity is nearly
thousand times as great as that of the
air far greater in proportion, than that
OF ship of solid lead OF gold would be
10 wafer. There is no obvious explanation
of this soaring fight, nor has any yet been
offered which is not open to some objec-
tion. Passing by the childish idea OF the
support being derived from the hghtness
of the birds hollow bones, or quilts. we
find ourselves restricted TO a very few
hypothesis indeed.
PERHAPS the first Of these is that the
bird is everywhere upOorne by Invisible
ascending currents Without in any way
denying that such currents exist or that
the bird may frequently utilize them, 1t
seems almost superfiuGus to enter upon a
refutation of the idea that these are uni
yersally present, even IL we allow that they
can have aseensional force sufficiently TO
sustain such masses in the air. What
goes up must come down ard there must
be areas where the currents are descend
ing to supply the void But perhaps bet
ter answer lies in the citation of the
simple and most familiar fact Of observa-
ton; that the great soaring birds (which
are chiefly of the vulture elass1 are found
uniformly suspended, frequently in large
numbers. above the carrion or other object
of their interest wherever il lies, and II is
too grotesque q suppositioE that an as
cending current capable of sustaining them
should always emsnate from such source
- hypothesis of such ascending currents
is not then, irrational as a partial ex-
PLANTATION, but wholly insufficient as
complete one.
.'The next which arises, and which to
an observer unframed in mechanics seems
extremely plausible. is that the wind holds
the bird up as il bears up kite. The
sight. familiar from childhood, of kites
sustained al great heights in the air with
out any power emanating from themselves
is perhaps responsible largely for this de-
fusion; for il is one TO suppose that the
bird. not upheld by any string. visible or
invisible actual or virtual, can sustain
itself in wind, at least II the wind
be what IL has lately been treated as be-
insa nearly homogeneous moving mass
Of air, with occasional little eddies or
disturbances which do not affect its fund
ameDtal quality OF a current flowing alto
gether like a river or tide.
1T is absolutely contradictory TO me-
chsnical principles. however. that in such
a uniformly moving mass Of air a kite
or any other body without internal power
or external support, or any bird on rigidiy
extended pinions can sustain itself except
momentaTily, any more than in an abso-
Lutte calm. The fact, however, that the
soaring birds very rarely indeed perform
their special eyolutions except In a wind
and do have TO resort to Tapping their
wings In calm. is so obvious that many
writers have tried to persuade themselves
that in some way or other well-known
laws can be eyaded and that the birds
can continuously soar in such a wind BY
a power derived in some way from il. I
can only say, however. that such action
10 mechanically impossible
Next. II Is indeed true that il there be
two winds. or two strata OF a wind, NOV
ing at different yelocities; it is in this
case mechanically possible that the evo-
luton can be performed, as Lord Ray
leigh has recently pointed out. Though
this is true cause as far as IL goes,
ii seems to me hardly necessary 20 say
that IL can account but for very limited
portion OF the actual phenomena
1T is indeed possible that as We fur
Their study that most marvellous struc-
Iure. the birds wing. we may find 1t ca
pable OF utilizing power latent in the in