Improvements in Aneroid Barometers.
Year: 1892

page_text: Date of Application, 3rd Mar., 1892
Complete Specification Left, 1st Nov., 1892-Accepted, 10th Dec., 1892
PROVISIONAL SPECIFICATION.
Improvements in Aneroid Barometers.
I, ROBERT CORRY of 9 and 11 Fenchurch Avenue, in the City of London,
Ship-owner, do hereby declare the nature of this invention to be as follows:-
My invention relates the ordinary aneroid barometer and is designated to
protect the said aneroids from a tendency to error in their readings and thus to
render them more reliable, particularly when used for ascertaining altitudes or
recording depths of mines, pits, etc.
It has been fully proved as the result of exhaustive experiment that all aneroids
when subjected to reduced atmospheric pressures, for any length of time, tend to
lose in comparison with the mercurial barometer and that this tendency to lose leads
to considerable error and causes the aneroid used in the ordinary way to be of very
little value in estimating high altitudes. It is also well known that the ordinary
diurnal variations of pressure generally have the effect of altering the index errors
of aneroids in one direction or the other from their first standard setting.
My invention is designed to avoid these errors and consists in making the case
and glass cover of an ordinary ancroid air-tight or in providing an air-tight casing
to contain the usual aneroid, the internal atmosphere of which casing may be
constantly maintained at a normal pressure when no observation is to be taken, and
may be placed in communication with the outer atmosphere only at such time as it
is desired to take au observation. The diaphragm and apparatus of the aneroid
barometer is thus kept at a normal pressure and in a perfect state of repose. The
diaphragm of the aneroid is only subjected for a very short time to the reduced
pressure, so that the conditions are practically the same as obtained when the
aneroid was originally tested under the air pump receiver and the results should be
equally accurate.
To carry my invention into effect I make the case of the aneroid air tight and
fit to stand a pressure of at least 8 lbs. on the square inch without. leakage or
deformation, the glass face being kept air tight by any suitable method.
The communication between the said air tight case and the surrounding
atmosphere is by a tight cock or valve of small bore, fitted to the case, and this
cock is adapted so that a small air force pump of any convenient form can be
tightly attached thereto, whereby after an observation at a low atmospheric
pressure the pressure of the internal atmosphere of the case can be at any time
gradually raised or lowered by a few strokes of the pump to a normal pressure.
The method of using my improved instrument is as follows:-
Before taking observations, such as altitudes, a reading should be taken in
comparison with a mercurial barometer, before starting, say approximately at sea
level by which any essential index error in the instrument should be noted and
calibrated.
The cock is then closed and the instrument retained at such normal pressure
until an observation is required. After such observation, the internal pressure
should be raised or lowered to the normal by the attachment and working of the .
air pump, the entry cock should be closed, and the apparatus maintained in this
condition at all elevations until a further observation is required.
The air tight case may be adapted to enclose an ordinary aneroid and case or as
above may form the only case of the aneroid.
Dated this 3rd day of Mazob 1902

page_text: CUMI DEI DI BUITICATION
Improvements in Aneroid Barometers.
I, ROBERT CORRY, of 9 and 11 Fenchurch Avenue, in the City of London,
Ship-owner, do hereby declare the nature of this invention and. in what manner
tlie same, is to be performed to be particularly described and ascertained in and by
the following statement :-
My invention relates to the ordinary aneroid barometer, and is designed to
protect the said aneroids from a tendency to error in their readings, and thus to
render them more reliable, particularly when used for ascertaining altitudes or
recording depths of mines, pits, etc.
It has been fully proved, as the result of exhaustive experiment, that all
aneroids, when subjected to reduced atmospheric pressures for any length of time,
tend to lose on the mecurial barometer, and that this tendency to lose leads to
considerable error, and causes the aneroid, used in the ordinary way, to be of very
little value in estimating high altitudes.
My invention is designed to avoid these errors, and consists in making the case
and glass cover of an ordinary aneroid air-tight, or in providing an air-tight casing
to contain the usual aneroid, the internal atmosphere of which casing may be
constantly maintained at a normal pressure, when no observation is to be taken,
and may be placed in communication with the outer atmosphere only at such times
as it is desired to take observations. The diaphragm and apparatus of the aneroid
barometer is thus kept at a normal pressure.
The diaphragm of the aneroid is only subjected for a very short time to the
reduced pressure, so that the conditions are practically the same as obtained when
the aneroid was originally tested, and graduated, under the air pump receiver,.and
the results should be equally accurate.
And in order that my invention may be the better understood I now proceed to
describe the same in reference to the drawings hereunto annexed, and to the letters
and figures marked thereon.
Figure is a section through the hermetically closed case and cock of my
aneroid.
Figure 2 is a section through the air force pump used therewith.
A is the usual elastic diaphragm chamber of an ordinary aneroid, which is
connected by known mechanism to an ordinary indicating pointer B, whereby the
fluctuations of the atmospheric pressure are indicated, when the atmosphere is
allowed free access to the space surrounding the said elastic diaphragm A.
In carrying out my improvement however, I place this known aneroid apparatus
within a non-porous and non-permeable case C, and hermetically close this case by a
glass cover D, which is adapted to make a specially air-tight joint with the case C.
This I effect by flanging the glass cover downwards at E to a considerable extent,
and fixing it by cement into a deep trough F, provided in the case for that purpose,
or by any other suitable method.
lbs. per
The whole aneroid apparatus is now hermetically sealed from the atmosphere,
and the case so constructed has been proved fit to stand a pressure of
square inch without leakage.
I fix a well fitted cock & of small bore into one side of the said case C, by which
the interior of the latter can be placed in free communication with the atmosphere
when desired.
The outer end of the cock G is provided with thread G' which enables the air
force pump H to be affixed to it, after an observation has been taken. Air is then
forced into the case by the action of the pump which for convenience is provided
with a plunger and cup leather K, which also acts as a suction valve on the return
stroke. A delivery valve of any approved construction is applied at the nozzle L

page_text: of the pump, and a convenient form of such valve may be two strips of oiled silk,
tied over the valve opening in the said nozzle.
11
The method of using my improved instrument is as follows :-
Before taking observations as to altitudes, a reading should be taken in com-
parison with a standard mercurial barometer before starting, say approximately at
sea level, and any index error in the instrument should be noted & calibrated.
The cock is then closed and the instrument retained at such normal pressure until
an observation is required. After such observation, the internal pressure should be
raised to the normal by the attachment and working of the air pump, the entry cock
should be closed, and the apparatus maintained, in this condition at all elevations,
until a further observation is required.
The air tight case may be adapted to enclose an ordinary aneroid and case or as
above may form the only case of the aneroid.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1st. In combination, for an aneroid barometer, a known elastic diaphragm or
chamber, known indicating mechanism connected therewith, an hermetically closed
and impermeable case containing the said aneroid appliance, a cock affixed thereto,
and an air-forcing hand pump adapted to be attached to the said cock substantially
as and for the purposes described.
2nd. The combination in an aneroid barometer with the known elastic diaphragm
or chamber, and the known indicating mechanism in connection therewith, of an
hermetically closed non perineable casing, of which one part is transparent and a
cock adapted by a screw thread for the attachment of a small air forcing hand pump,
substantially as and for the purposes described.
3rd. In an aneroid barometer an hermetically closed surrounding casing of
non permeable material, a cock affixed therein, a glass face thereon, adapted to
withstand a pressure of one atmosphere, and formed with a flange of considerable
depth, bent at right angles to the face, and cemented into a circular trough or recess
of the said case substantially as and for the purposes described.
Dated this 1st day of November 1892.
FELL & WILDING,
1, Queen Victoria Street, London, E:C., Agents for the Applicant.