The Savannah morning news., 1904-07-10
MEASURING PRESSURE OF WIND.
Unique Apparatus on the EiHel Tow
err shows the Resistance of the Air.

Unique Apparatus on the Einel Tow
err shows the Resistance of the Air.
From the Scientific American.
Some very interesting experiments
upon the resistance of the air have
been recently made by NJ. G. Eiffel at
the tower which bears his name, by
means of an apparatus of his inVen-
ton which may be daily seen in oper-
alton when the air is calm. At a given
signal a cylinder carried by a double
spring falls with great veloci-
ty from the second floor OF
the tower Chat is to say, from
a hight of about 1875 feet, along
vertical cable, and then progressively
slows up, and stops without any shock
at 3.28 feet from the ground, remain
ing attached to the cable. This cylin-
der, part of which is conical, carries
in front a plate which is thrust back
ward by the pressure of the wind dur
ing the fall. Such displacements COM
press an acuractely tared spring which
measures the pressure and inscribes II
upon registering drum, the revolu
ton of which is regulated by the fall
Itself The ordinary inscribing style
is replaced by tuning fork that makes
a hundred vibrations a second. When
the apparatus is opened there is, there
fore, found inscribed upon the drum
an undulating curve that gives for
every point the hight of a fall, the
pressure acting at this moment, and
the velocity, within an approximation
of a huhdredth of a second. This Is
the first time that one and the same
apparatus has continually indicated
these various results from the zero We
locity to that of 1870 feet a second,
which is that of the most violent winds
AS the pressure device may be OF
any form and size whatever Ca normal
or oblique plane, a cone, sphere or
cylnder), the apparatus is capable Of
giving more accurate results than have
hitherto been obtained in experiments
on the resistance that the air offers
to moving body, and which is nothing
else than the pressure of the wind upon
a stationary body.
Such determination presents great
practical interest either as regards the
utilization of the pressure OF the wind
as a motor or the resisting of it, as
becomes necessary in the practice OF
the profession Of the engineer and IN
experiments with dirigible balloons.
In order to complete the description
of the apparatus the principle of which
has just been indicated 1t suffices to
add that in order to diminish the effect
of the velocity of this mass of 2S5
pounds moving at tue Idle u Low lett
second, say nearly ninety miles an
hour, the frame of the apparatus Is
carried by a very powerful double
spring. which slides freely along the ca
BILE as far as to within sixty-tive feet
of the ground. at which point the
diameter Of the cable progressively
widens and the double spring also is
forced to widen, and then exerts a
pressure upon the cable, and through
it's friction gradually diminishes the
velocity.
The experiments have show that the
pressure of the wind is No ably less
than that admitted up to the present.
After they have been finished this
question, which has hitherto been very
uncertain will have made an import
ant progress and have demonstrated
once again the services that the Eiffel
Tower is capable of rendering to
science.