IMPROVEMENTS IN INSTRUMENTS FOR RECORDING THE PRESSURE OF GAS
Year: 1884

page_text: I, WILLIAM HENRY COWAN of Edinburgh, in the County of Mid Lothian,
North Britain, Gas Apparatus Manufacturer do hereby declare the nature of my
said invention for "IMPROVEMENTS IN INSTRUMENTS FOR RECORDING THE PRESSURE
OF GAS," to be as follows:-
This invention has for its object the application of photography to gas pressure
gauges for the purpose of producing by this means a diagram or register of the
pressure, after the manner of the diagrams made by the ordinary pressure register,
or the registering pressure gauge, and with less friction. The invention is not
limited in its application to any particular form of pressure gauge, pressure register,
or registering pressure gauge, but is applicable to those instruments generally.
In applying the invention to the ordinary pressure gauge, one mode is, to place
behind one of the "legs" of the gauge a roller or a disc, covered with sensitized
paper, or other suitable material divided into spaces by lines so as to show periods
of time and degrees of pressure in a manner similar to that commonly in use in
ordinary pressure registers, and registering pressure gauges.
The roller or disc carrying the sensitized paper or other suitable material is
enclosed in a light tight case, with a shutter to cover an aperture which may be
opened automatically by the placing of the roller or disc in its position, or otherwise,
or by hand if preferred.
The water or other liquid in the pressure gauge tube is rendered opaque so that
light will not pass through it to the sensitized paper, hence the light can only reach
the paper through the part of the tube which is unoccupied by liquid, the result
being that the light only affects the paper through that part of the aperture in the
case which is above the height of the opaque liquid in the gauge tube.-And as
the roller or disc is revolved by clock-work once in twenty four hours, or in any
other desired period of time for which it may be arranged, it follows that the upper
part of the paper will be affected, all round, down to the level of the liquid in the
gauge tube. But as changes of pressure change the height of the liquid, the result
will be the production of a diagram exactly indicating the varying degrees of
pressure, the times of their establishment and the periods of their duration.
In applying this invention to the ordinary pressure register or to the registering
pressure gauge, one method is to enclose the ordinary roller or disc, but covered

page_text: with sensitized paper, in a light-tight case with shutter, similar to the one above
described, and to make the rod which usually carries the pencil or other marking
instrument to carry instead thereof, a screen to cover the aperture in the cover or
shutter of the roller or disc. In the screen so carried, there is an aperture through
which alone light can reach the sensitized material on the roller, or disc. The
result is that as the screen rises and falls the pencil of light acts upon the parts of
the paper exposed, and describes upon it a diagram showing the pressures in the
manner above set forth.
In applying the invention to the gauge known as "King's gauge," one mode is
to place behind the pointer or other indicator a roller or disc, as above described,
and to so arrange the pointer or other indicator, that it will cover and uncover the
aperture in the light-tight cover or shutter in the roller, or disc, through which
only light can reach the sensitized paper.
Daylight not being always available, artificial light may be employed to impress
the sensitized paper, or other such material, which may be developed by any
suitable process.

page_text: I, WILLIAM HENRY COWAN of Edinburgh in the County of Mid Lothian,
North Britain, Gas Apparatus Manufacturer do hereby declare the nature of my
invention for "IMPROVEMENTS IN INSTRUMENTS FOR RECORDING THE PRESSURE OF
GAS" and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement reference being had to the
accompanying drawings and to the letters and figures marked thereon, that is to
Bay-
This invention has for its object the construction of apparatus whereby the
application of photography to gas pressure gauges for the purpose of producing
by this means a diagram or register of the pressure after the manner of the
diagrams made by the ordinary pressure register, or the registering pressure gauge
and with less friction, may be employed. The invention is not limited in its
application to any particular form of pressure gauge pressure register, or registering
pressure gauge but is applicable to those instruments generally.
In applying the invention to the ordinary pressure gauge, one mode is to place
behind one of the "legs" of the gauge a roller, a drum, or a disc, covered with
sensitized paper, or other suitable material divided into spaces by lines so as to
show periods of time and degrees of pressure, in a manner similar to that commonly
in use in ordinary pressure registers, and registering pressure gauges.
The roller or disc carrying the sensitized paper or other suitable material is
enclosed in a light tight case, with or without a "shutter" to cover an aperture
which may be or not opened automatically by the placing of the roller or disc in
position (or otherwise) or by hand if preferred.
The water or other liquid in the pressure gauge tube may be rendered opaque so
that light will not pass through it to the sensitized paper, hence the light can only
reach the paper through the part of the tube which is unoccupied by liquid, or the
opaque part of the float with which the gauge is provided, the result being that
the light only affects the paper through that part of the aperture in the case which
is not obstructed by the opaque liquid in the gauge tube or the float just mentioned.
And as the roller, drum or disc is revolved by clockwork once in twenty-four hours,
or in any other desired period of time for which it may be arranged, it follows that
the upper part of the paper will be affected all round, down to the level of the
liquid in the gauge tube, or the opaque part of the float. But as changes of
pressure change the height of the liquid the result will be the production of a
diagram exactly indicating the varying degrees of pressure, the times of their
establishment and the periods of their duration.
In applying this invention to the ordinary pressure register, or to the registering
pressure gauge, one method is to enclose the ordinary roller, drum or disc, but
covered with sensitized paper in a light tight case with shutter similar to the one
above described, and to make the rod which usually carries the pencil or other
marking instrument to carry instead thereof, a screen to cover the aperture in
the cover, or shutter of the roller, drum or disc. In the screen so carried there is
an aperture through which alone light can reach the sensitized paper or other
material on the roller, drum or disc. The result is that as the screen rises and
falls the pencil of light acts upon the parts of the paper exposed and describes
upon it a diagram showing the pressures in the manner above set forth.
In order that the foregoing may be more easily understood drawings are attached
hereto of which the following is a description, similar letters referring to the same
parts in each of the views. Fig 1 is a front elevation of the apparatus, Fig 2 is a
right hand end elevation, Fig 3 a back elevation and Fig 4 a plan of the apparatus.
Fig 5 is a view of the cylindrical light tight case of the gauge showing the slit P.
Fig 6 is a vertical section of this case and exhibits the roller or drum whereon the

page_text: sensitized diagram paper is placed, and Fig 7 is a plan of the cylindrical case with
the cover removed in order to show the drum or roller also in plan. Fig 8 exbibits
the application of the invention to a pressure register."
«
In the Figs A is the clock (from which the pendulum has been removed) which
gives motion to a spindle B carrying a mitre wheel C.-This mitre wheel in its
turn causes the rotation of the horizontal wheel D, which gives motion to the
upright shaft E Figs 5 and 6, and on which, and within the cylindrical case F
the roller or drum G is fixed. Round the drum G a sensitized register paper ruled
with appropriate lines as shown at H in Fig 6 is fastened in the usual manner as
at a Fig 7. The toe of the upright shaft works in a step fixed to the base plate
and the upper part works in a bearing I Fig 4 formed in or attached to a bar J,
that is supported by the two pillars K, L. Tho bar is hinged to the pillar K at M
and to the pillar L it is fastened by a screw at N, so that on lifting the bar J and
removing the cover O of the cylindrical case F the drum may be taken out, the
diagram paper removed and a fresh one placed thereon, and the drum restored to
its original position. By looking at Fig 7 it will be observed that the diagram
paper is brought into as near proximity as possible to the slit P in the cylindrical
case F, the slit being made in an indent Q formed to receive the glass leg R of the
gauge. The gauge glass R is fixed to a frame S, T, the pillar part T of the frame
being pivotted to the base plate at U, so that the frame can swing outwards,
withdraw the gauge glass from the indent Q and assume the position as drawn in
Fig 4. V is a water tank of considerable area and forms the other leg of the
gauge R, and when water is poured into V through an orifice at b it flows through
the pipe h into the hollow frame S T and rises in the glass leg. The area of the
tank being so much greater than R practically the whole of the pressure is shown
in the gauge glass. W is a tap for adjusting the level of the water and X is a tap
for drawing off the whole of the water. Gas is admitted into V by the pipe Y.
At Z there is an arrangement shown for holding the drum or roller in the proper
position until the time arrives for starting it, when by releasing a peg that takes
into a hole c in the drum shown in Fig 7 the drum is at liberty to revolve.
The liquid supplied to R is either suitably coloured or is provided with a float
rendered opaque except at the point coincident with the top of the water and
through which the light may pass.
In Fig 8 which represents a pressure register & is a tank in which a floated
gas holder e rises and falls. The top of the holder carries a lath or screen f, and
in this screen at g there is a very small hole. The hole is made exactly opposite
the slot P in the cylindrical case so that as the lath or screen rises and falls the
effect upon the sensitized diagram paper before described will result.
Daylight not being always available, artificial light may be employed to impress
the sensitized paper, or other material which may be developed and fixed if
necessary by any suitable process.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is,
The construction of apparatus for the purpose of recording the pressure of gas,
as herein described and shown on the drawings.