Evening star. [volume] (Washington, D.C.) 1854-1972, 1891-04-21

Edward S. Morse Salem; Fredk W. Putnam.
Cambridge; Ira Remsen, Baltimore; Henry A.
Rowland, Chas. A. Schott, Washington; Francis
a; Walker. Boston, Chas.A A. White, Washington;
Iheo. n. Gill, Washington; II. c. Meigs,
Washington.
| THE PUBLIC SESSION.
The public session began at noon in the lee
ture room without any preliminary flourish.
Besides the members of the academy present
there was an audience of rs or 100 Prof.
| Marsh, president of the academy mounted the
| platform, placed his silk nat on the desk in
'front.' OF MIN and simply said; The academy
VIII now come to order." He then announced
.n1 nist paper OF the day, which was one by A.
8. Packard on Further Studies on the Brain of
Limulus Polyphemus.n The paper was read
by DIR. Theodore n. Gill.
PROF. LAsaLEY's TALK
Prof. Langley was announced as the author
OF the next paper. Prof Langley did not read
paper, but talked to the academy. giving the
remarkable results of experiments he had made
In the field Of aerodynamics.
Prof Langley said he presumed the subject
announced for his paper might be a surprise.
as 1t was one the iscussion of which had been
| confined more to the sphere of charlatanism
than that of science
1t Is the subject of artificial flight, the pro-
polling through the air of bodies heavier than
the air. The perpetual miracle of a souring
biro was 80 familiar, he said, that it ceased to
excite wonder.
About five years ago he resolved to expert
ment In the matter, and, with the pecuniary
aio OF a gentleman since dead he had set I'D in
Ihe grounds of the Allegheny observatory
Mhiriih9 machine on q scale never before tried
It's use was to create an artificial wind. Its
diameter was sixty feet and it was driven by
| steam engine OF ten or twelve horse power
There was hardly anything. he said, in which
statements of men Of most honored names
were to be taken with more caution than state
| ments regarding aerodynamics because there
was so little founded on actual experiment
In this connection he referred to a paper by
eminent French physicists. in which it was
| held that in order to calculate the work one
must put out to lily it must first be determined
now much work is required to merely suspend
the body in the air.
Iheconclusion solemnly reached is that swal-
low to fly forty miles an hour must exert one
| tenth OF horse power, eagle ten horse
power and Egyptian crane weighing forty
pounds about forty horsepower. To suppose
that an eagle or buzzsrd is as strong as twelve
or thirteen horses was absurd. but the idea
seemed not to trouble these writers at ALL
Prof Langley said the first experiment. he
made was to test the question, Does it require
more power to move laterally than to stand
still in the air?
WHAT AN EXPERIMENT SHOWED.
He explained how he had suspended a fat
brass plate from the arm of the whirling ma
chine by spring. When the machine was put
In motion and the plate encountered an artifi-
cial wind going forty miles an hour the spring
instead OF elongating actually shortened. show
ing that the weight or power required to sus-
pend the plate was less when In motion than
when it was standing still.
This he considered was demonstratiye evil
dence that there had been some gross concep-
tions on the subject. After it was done it be-
came apparent at once that what occurred
should have occurred.
Prof. Langley said he then begun the study
OF another matter connec ed with it. He found
that the brass plane when placed horizontally
and moved forward laterally sank to the ground
Slowly as II the ar hao become like dense
0'I Ta ;II,s..a,ai
man skating over thin ice. He sunnossS that
the man went over 100 different cakes of ice
IN second, each cake being Of mass equal to
nis own. IN ,nat time, ne said, speaking ap-
PfoAihateiy, tne ice "ouid SINK or yield only
one one one-lundredtn as much as 1t would If he
iia1 s'ooa curing that ,inae on one cake.
ny sunlcien.y raPlu progress, ne said, one
Souiu 90 over tne most yielding surface without
oenuing II mucn.
d. ne salu the poets inquire OF swift Camillas
n'gna o CT the unoending grain was scientifically
possible
Prof Langley further illustrated bv means NJ
a simnle annaratps He had a ,h;n r.--.,s.
Il po ~ n"o 'ni,i narrow STAT
OF plane OF WOOD about three feet long and two
inches wide, from the center of which pro-
iected handle about two feet long with smou
brass knob on the end Of it. First, he let the
STAT with the handle downward fall from his
manu- S;u, S .h ny. nJ.I,s s.ationary. linen he
horizontal plane or ala, WAS revoixsd ana l.. me
fall while whirling. It was obvious that il
took q second or two more to fall four feet
while in motion than when il was dropped
from the hand without motion.
Prof. Langley explained various expert
ments made with his whirling machine and the
delicate and ingenious apparatus by which the
results were recorded.
THE POWER N ArrAIx.r,r
Al a conclusion of hi. exno-;,.o,,.
4, e~pei'eh"' no said
tnat tne amount OF power required for arti-
fetal fight was perfectly sttainable by steam