El Paso herald. (El Paso, Tex.) 1901-1931, 1913-08-11


department and are expected TO IN
cLude all that IS newest and most prac-
teal in aeronautic construction. They
are to be tested more rigidly than have
any other flying machines which have
! been purchased by the United States
government.
To secure the standards by which
accurate altitude tests might be made
/ the bureau Of standards has been ex-
! perimenting for months with aneriod
| barometers, the instruments by which
/ attitudes have been measured by avia-
I Tors from the beginning of the science
! These experiments give the surprising
} result that, according to the mOsI
! scientific test ever made in the world
no aneroid now in existence can be
proved TO be accurate. Consequently,
I every one of the worlds records for
/ altitude may vary thousands of feet
/ from the truth.
Is French Invention.
/ The aneroid barometer is a small in
strument used for registering atmos-
! pheric pressure at different attitudes
! 1t was invented by Vidi, a French sci
enlist in Paris in 1913. The principle
OF the aneroid used for testing these
great war aeroplanes does not differ
/ from that of the original instrument
/ used by VidL The aneroid has had
comparatively little use until the de-
Velopment Of aviation 1t was practi-
cally unknown outside of scientific
circles Travellers in unknown regions
used 1t for testing mountain heights
and atmospheric conditions but it had
no general use so, excepting to a few
scientists it made little difference
or not.
As it is the only instrument known
10 register altitude, the development or
aviation called it into popular favor
When the War department prepared
speclfled requirements for its aero
planes the bureau Of standards began
70 test the instrument by which the al
tltude was to be measured. These tests
nave been most intricate and careful
The results indicate inaccuracies which
world
Collection Is Made.
A collection of all of the recognized
makes Of anerOid barometers in the
world was secured by the bureau Of
standards for making these tests.
Each was subjected to the same rigid
examination and experiment. Speci-
ally designed apparatus was provided
Tor raising and lowering the tempera-
Iure TO correspond with atmospheric
changes at various attitudes. Scientific
observations of every change were
taken microscopically and recorded ac-
curately for months. These records
prove the great Inaccuracies of all Of
these instruments It was difficult to
secure two identical registrations from
the same instrument under the same
atmospheric conditions.
No Records Correct.
Many conditions affect the sensitive
ness Of the little instrument For in
stance. If a flying machine ascends at
a nigh rate Of speed, a greater de-
crease in the pressure of air will bss
noted by the aneroid than if the same
altitude was achieved by q slower
ascent At present no means of max
ing accurate allowance for discrepan-
c1eS from this cause are known. The
aneroid commonly used in aviation is
supposed to be able to register an al
utude Of at least Is, 900 feet. There is
no certainty that it ever has done So
Ihere IS no method of determining alb
solutely whether or not any aeroplane !
ever rose to more than q fraction of
the altitude accredited to it
War AerOpIanes to Be Models.
The three new war aeroplanes, now
almost completed, are TO be tested ac-
cordfng to the strictest specifications I
covering every point Each must
show minimum speed not falling be- (
low 80 miles with maximum OF at /
least So miles an hour. It must be 1
capable of cross country run of $50 ]
miles at an easy glide and OF executing 4
a 1lgure eight in the air in a rectangle /
of space not exceeding 500 by $50 feet !
without decreasing its altitude more /
than 100 feet
1t must be able to carry a load Of /
$50 pounds in addition to two persons. /
a pilot and an observer besides sN7ffi-
cient oil and fuel for at least four 4
hours 1t must be equipped with en- 4
S1neS capable Of being throttled so J
that one person may operate the air !
ship If need be. 1t must be CAPABLE of 4
being shipped by road so that it can
not be more than ten feet wide in !
shipment and it must be so constructed |
that 1t can be made ready for opera /
ton IN one hour, without recurring the
services Of more than six men
while these machines are all being 1
built by American firms they are to 4
be equipped with propelIing power Of /
foreign make. This is the first time
this government has permitted any
other than American machinery in an /
aeroplane designed for public use and
II is believed that the purchase Of
these now under consideration will act
as a stimulus to encourage the i'm
provement of the aerOnautic machinery
Of this country The three engines Sc
lected are the Austro-Daimler, the
Gnome and the Renault The cost of
each fully equipped aeropIane Will
Approximate $40. 900
Must Go 1000 Feet In 10 Minutes
The altitude requirement for each OF
these machines is to be an ascent Of I
1000 feet in 10 minutes. As this al
1tude can only be measured by the (
aneroid, there is no means of knowing
the new machines will comply
with it or not The anerOid which has
been unofficially adopted for the test
ing of war aerOplanes consists of three !
parts which are enclosed in a black
Gather case resembling a tiny camera
n appearance.
Watch Form of AneroId.
The watch form of aneroid is the
oldest and best known. It resembles !
an old fashioned watch in appearance
The indicator moves around upon its
ACE like the hands of a watch, regis
-ering degrees of atmospheric pressure !
instead of seconds, minutes and hours
II time The reading of an aneroid re-
Iuires closest attention. The differ
snce Of the hundredth part of an inch
upon the register may amount to a
Inference of a thousand feet in the
altitude supposed to be measured.
Because of the constant changes it was
difficult to read the old aneroid cor
'ectly. With the register, the readings
nay be microscopic and the smallest
variance will be noted.
In testing anerOid barOmeters several !
instruments are usually used ]
n conjunction with a mercuriaI barom-
,ter and an average secured from the
'ecOrds of all The tests made at the
bureau of standards have been more (
accurate in their methods but the re-
ults show the absolute necessity of
occurring some reliable means of test
ng attitudes The progress of aviation
must be materially retarded unail such !
n instrument is discovered or some /
means of improving the aneroid de-
Used to secure a greater degree Of
The Improvement Of the aneroid Is
he most probable solution of the dir |
iculty. 1t has been noted that +be an