IMPROVEMENTS IN INSTRUMENTS FOR INDICATING PRESSURE OR VACUUM
Year: 1855

page_text: LETTERS PATENT to James Egleson Anderson Gwynne, of Essex Wharf,
Essex Street, Strand, in the County of Middlesex, Engineer, for the
Invention of "IMPROVEMENTS IN INSTRUMENTS FOR INDICATING PRESSURE OR
VACUUM."
Sealed the 20th May 1856, and dated the 29th November 1855.
PROVISIONAL SPECIFICATION left by the said James Egleson Anderson
Gwynne at the Office of the Commissioners of Patents, with his Petition,
on the 29th November 1855.
I, JAMES EGLESON ANDERSON GWYNNE, of Essex Wharf, Strand, in the
County of Middlesex, Engineer, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN INSTRUMENTS FOR INDICATING PRESSURE OR
VACUUM "to be as follows:-
The said Invention consists in a new & improved system of constructing
instruments for the indication of the pressure of fluids or gases.
For steam pressure I construct a siphon, so that when the steam becomes
condensed, the said siphon will retain the water so condensed, & prevent its
return to the boiler; (or the siphon may be filled with water or other fluid, as
oil, before applying it to the steam.) The pressure of the steam is in this way
communicated to the water, which has access to a cylinder, on the top of
which there is a diaphram or piston of leather or other suitable material

page_text: secured, & so constructed that it will move up & down the length of its
stroke without friction or injury to the said piston or diaphram. A piston
rod is attached to the said piston or diaphram, which may be worked in
a guide, if required; the end of this rod is attached by a moveable joint
to the arm of a segment of a circle, the circumference of the said segment
having teeth cut in it, & into which a pinion wheel is geered; on the
pinion wheel spindle an indicating hand is placed before or over a properly
divided dial. A spring is also attached to the arm of said segment, by means
of which the instrument can be regulated to the greatest accuracy in a very
simple manner. The action is as follows:-The pressure of the steam through
the medium of the water forces up the piston or diaphram, which communi-
cates its motion through the piston rod to the segment, the teeth of which
cause the pinion carrying the indicating hand to revolve the distance through
which the hand passes, being regulated by the spring.
Another mode of construction is by placing a flat spring directly over the
piston rod; resting on the top or other side of the spring there is a cam or
arm, connected with or forming part of the segment of a circle, having teeth
cut in the segment's circumference, & working into a pinion, as before
described. When pressure is applied to the piston or diaphram, it presses or
forces up the spring, and the cam or rod (in connexion with the segment)
being pressed upon, gives motion to the circumference of the segment, & thus
motion is given to the indicating hand, as before described. The spring is
held by a forked lever, which can be opened or closed, as required, by set
serews, & by increasing or diminishing the strength or stiffness of the spring,
the distance through which the hand is required to pass can easily be obtained.
When used for indicating the pressure of liquids a siphon need not be used.
A valve may also be used instead of a siphon for steam pressures.
When used as a vacuum guage, the spring is placed on the side opposite to
that on which it is used for indicating pressure, or the piston rod placed on the
opposite side, the dial of course being suitably divided.
by the said James Egleson Anderson Gwynne in the Great Seal Patent
Office on the 28th May 1856.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
EGLESON ANDERSON GWYNNE, of Essex Wharf, Essex Street, Strand, in the 3
County of Middlesex, Engineer, send greeting.

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-ninth day of November, in the year of our
Lord One thousand eight hundred and fifty-five, in the nineteenth year of
Her reign, did, for Ierself, Her heirs and successors, give and grant
unto me, the said James Egleson Anderson Gwynne, Her special licence
that I, the said James Egleson Anderson Gwynne, my executors, adminis-
trators, and assigns, should at any time agree with, and no others, from
time to time and at all times thereafter during the term therein expressed,
should and lawfully might make, use, exercise, and vend, within the United
Kingdom of Great Britain and Ireland, the Channel Islands, and Isle of Man,
an Invention for "IMPROVEMENTS IN INSTRUMENTS FOR INDICATING PRESSURE OR
VACUUM," upon the condition (amongst others) that I, the said James Egleson
Anderson Gwynne, by an instrument in writing under my hand and seal,
should particularly describe and ascertain the nature of the said Invention,
and in what manner the same was to be performed, and cause the same to
be filed in the Great Seal Patent Office within six calendar months next
and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said James Egleson Anderson Gwynne,
do hereby declare the nature of my said Invention, and in what manner the
same is to be performed, to be particularly described and ascertained in and by
the following statement and accompanying Drawings (that is to say):-
My Invention consists in a new and improved construction of instruments
for indicating the pressure of fluids or gases, such as steam, water, &c., and
also for indicating the amount of vacuum in condensers, &c. When used for
indicating the pressure of steam or gases, I sometimes construct the gauges
with a syphon inside the case that will retain a portion of water, oil, or some
such substance, as a medium for the steam or gases to act upon, and prevent
its return to the boiler or generator, and through which to communicate the
pressure of the steam, gas, &c. The fluid contained in the said syphon has
access to a cylinder or other suitably formed chamber, on the top of which is a
diaphragm or piston of india-rubber, gutta percha, leather properly prepared, or
any suitable material, properly secured, and so constructed that it will move up
and down the distance required without friction or injury to the piston or
diaphragm. I construct the piston in various ways; sometimes attaching the
rod, through which I get my motion to the flexible diaphragm or piston, and
which is made adjustable, so that I can lengthen or shorten it to any point
desired; or I may rest a small piston or solid plunger, which fits or covers the
top of the said diaphragm, which is constructed to be capable of adjustment,
and not attached to the diaphragm, but simply resting upon it. The piston

page_text: rod, whether attached direct to the diaphragm, or to the plunger resting on the
top of it, is attached by a moveable joint to the arm connected with a segment
of a circle; the periphery of the segment has teeth cut in it, into which a
small pinion is geared; the spindle of the pinion wheel passes through a dial
plate, and carries an indicating hand that is fixed to the spindle, and oscillates
round a properly divided dial, indicating the degrees of pressure.
In another modification, I place a convolute or cylindrically coiled spring
chain, cord, or other suitable flexible attachment round the spindle or axis of
the hand, made fast at one end, with the other end secured to the end of a
rod, beam, or lever, which is attached in a suitable manner to the piston
or diaphragm rod. The action will produce the effect of moving the hand or
finger round the dial, according to the pressure. A spiral spring is attached
to the arm of the segment insted of the rack segment, which may be variously
fitted and connected; sometimes I employ them shut, and by the pressure they
are opened; at other times I uso them open, and the pressure tends to shut or
close them. I construct a small slide, which can be placed and made fast at
any part of the arm of said segment, and which keeps the upper end of the
spring steady in its place; another slide at the bottom or lower end of the
spring can also be made fast at any required place, and, by moving the spring
to the proper part of the arm or bar of the segment, I can adjust them to what
amount of pressure I desire. When I want to indicate high pressures, I
prefer using to or more springs, arranged as above described, as I find the
action more accurate and not so liable to alteration or derangement as one
.spring. I coat or cover by electrotype, or otherwise, the springs with metals,
or with any preparation to prevent their oxidation.
The action of the gauge is as follows:-The pressure of the steam, gas, &c.,
acting through the medium of the water, oil, or other fluids contained in the
syphon or body of the instrument, forces up or presses against the diaphragm
or piston, before described. The motion given to the diaphragm or piston is
communicated through the piston rod to the toothed segment, which
gear into
the pinion, and cause it to rotate, and the indicating hand with it, round the
figured dial, indicating the pressure applied.
In another arrangement, the motion of the bar or lever has a similar
effect on the spring, chain, cord, or other flexible medium used, which causes
it to coil or uncoil and move the hand with it; the distance through which
the indicating hand passes is regulated by the spring, which is made to press
more or less against the piston or diaphragm, or oppose its progress, according
as it is moved backwards and forwards along the arm of the segment.
When used as a vacuum guage I dispense with the syphon altogether, (and

page_text: this
may be done in the construction of the pressure gauge, if desired, pro-
vided an external syphon is used.) I secure the piston rod to the piston or
diaphragm, and attach the other end of my piston rod to the opposite or outer
side of the centre on which the segment oscillates; this gives me the same
motion as in the pressure gauge, but in the arrangements of the vacuum
gauge the action is produced by the weight of the atmosphere.
In another arrangement, I fix the spring on the upper side of the arm of the
segment; the action is the same as in the pressure gauge, but the motion is
communicated in an opposite direction, and my arrangements is therefore the
reverse of that used for the pressure gauge.
In the accompanying Drawings, Figure 2 represents a front elevation of the
pressure gauge; Figs. 1 and 5 represent other arrangements of the pressure
gauge in section; Figures 3 and 4 represent the arrangement and construction
of my vacuum gauges. (The same letters refer to the same parts in all the
Figures.)
Figure 1 shews one arrangement of my pressure gauge with the syphon
D, C, enclosed in the case. C is a small tube, open at the upper end, and
enclosed by a larger tube D, closed at the upper end. The passage E, at the
bottom of the outer tube D, communicates with the chamber F; when this
chamber and passage, together with the outer tube D, is once filled with
water, oil, or other suitable fluid, the inner tube C prevents its running
away or leaving the outer tube D, unless when the height exceeds the top
of the tube C. A syphon may also be made surrounding the inner portion of
the outer case, which will answer equally well. G is the flexible piston or
diaphragm, and II the piston rod. In Figure 1, the piston rod II is attached
or fastened to the flexible piston or diaphragm. Figure 5 represents the piston
rod unattached, but resting upon the surface or top of the said piston or
diaphragm, the solid plunger or piston Z fitting over or covering the dia-
phragm, and adjusted to the proper length by the screw, as shewn. I, the
centre, on which the segment N rotates; K, the point to which the end of
the piston rod is attached to the arm of the said segment; O, the pinion wheel,
working into the teeth in the circumference of the segment, the pinion carrying
the hand R, placed over a properly divided dial S, S, (Figure 2); M repre-
sents the spiral spring; L, the moveable piece, which slides along the bar or
arm of segment, and keeps the spring in its proper place; Q, the slide, for
securing the other end of the spring. In Figure 2, two springs M, M, are
shewn. Figures 2 and 5 are shown without any internal syphon. Figure 5
shews the piston rod placed or secured to the other side of the bar or arin of

page_text: segment, and the spring is placed above instead of below the arm or bar; the
spring is also made to close instead of open by the pressure.
In the vacuum gauges, Figures 3 and 4 shews the piston rods II, II, as
secured to the pistons or diaphragms; G, G, Figure 3, shews the piston work-
ing from the opposite or outer side of the centre on which the segment N
rotates; the spring M is placed below, and it opens by the action of the gauge,
In Figure 4 the piston rod is worked from the inner side of the centre of the
segment, and the spring is placed above, and shuts or is compressed by the
action of the gauge of the working parts. Fig. 6 represents another arrange-
ment of the working part of gauge, previously described. Many minor
modifications may be made in the arrangement, which it is unnecessary to
describe.
Having thus described the nature of my said Invention, I would have it
understood that what I claim is, the construction and arrangement of pressure
and vacuum gauges, as described.
In witness whereof, I, the said James Egleson Anderson Gwynne, have
hereunto set my hand and seal, this Twenty-eight day of May, in tho
year of our Lord One thousand eight hundred and fifty-six.
JAMES E. A. GWYNNE.
(L.S.)

page_text: LETTERS PATENT to James Egleson Anderson Gwynne; of Essex Wharf,
Essex Street, Strand, in the County of Middlesex, Engineer, for the
Invention of "IMPROVEMENTS IN INSTRUMENTS FOR INDICATING PRESSURE OR
VACUUM."
Sealed the 20th May 1856, and dated the 29th November 1855.
PROVISIONAL SPECIFICATION left by the said. James Egleson Anderson
Gwynne at the Office of the Commissioners of Patents, with his l'etition,
on the 29th November 1855.
I, JAMES EGLESON ANDERSON GWYNNE, of Essex Wharf, Strand, in the
County of Middlesex, Engineer, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN INSTRUMENTS FOR INDICATING PRESSURE OR
VACUUM" to be as follows:-
The said Invention consists in a new & improved system of constructing
instruments for the indication of the pressure of fluids or gases.
For steam pressure I construct a siphon, so that when the steam becomes
condensed, the said siphon will retain the water so condensed, & prevent its
return to the boiler; (or the siphon may be filled with water or other fluid, as
oil, before applying it to the steam.) The pressure of the steam is in this way
communicated to the water, which has access to a cylinder, on the top of
which there is a diaphram or piston of leather or other suitable material

page_text: secured, & so constructed that it will move up & down the length of its
stroke without friction or injury to the said piston or diaphram. A piston
rod is attached to the said piston or diaphram, which may be worked in
a.guide, if required; the end of this rod is attached by a moveable joint
to the arm of a segment of a circle, the circumference of the said segment
having teeth cut in it, & into which a pinion wheel is geered; on the
pinion wheel spindle an indicating hand is placed before or over a properly
divided dial. A spring is also attached to the arm of said segment, by means
of, which the instrument can be regulated to the greatest accuracy in a very
simple manner. The action is as follows:-The pressure of the steam through
the medium of the water forces up the piston or diaphram, which communi-
cates its motion through the piston rod to the segment, the teeth of which
cause the pinion carrying the indicating hand to revolve the distance through
which the hand passes, being regulated by the spring.
Another mode of construction is by placing a flat spring directly over the
piston rod; resting on the top or other side of the spring there is a cam or
arm, connected with or forming part of tho segment of a circle, having teeth
cut in the segment's circumference, & working into a pinion, as before
described. When pressure is applied to the piston or diaphram, it presses or
forces up
the spring, and the cam or rod (in connexion with the segment)
being pressed upon, gives motion to the circumference of the segment, & thus
motion is given to the indicating hand, as before described. The spring is
held by a forked lever, which can be opened or closed, as required, by set
screws, & by increasing or diminishing the strength or stiffness of the spring,
the distance through which the hand is required to pass can easily be obtained.
When used for indicating the pressure of liquids a siphon need not be used.
A valve may also be used instead of a siphon for steam pressures.
. When used as a vacuum guage, the spring is placed on the side opposite to
that on which it is used for indicating pressure, or the piston rod placed on the
opposite side, the dial of course being suitably divided.

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-ninth day of November, in the year of our
Lord One thousand eight hundred and fifty-five, in the nineteenth year of
Her reign, did, for Herself, Her heirs and successors, give and grant
unto me, the said James Egleson Anderson Gwynne, Her special licence
that I, the said James Egleson Anderson Gwynne, my executors, adminis-
trators, and assigns, should at any time agree with, and no others, from
time to time and at all times thereafter during the term therein expressed,
should and lawfully might make, use, exercise, and vend, within the United
Kingdom of Great Britain and Ireland, the Channel Islands, and Isle of Man,
an Invention for "IMPROVEMENTS IN INSTRUMENTS FOR INDICATING PRESSURE OR
VACUUM," upon the condition (amongst others) that I, the said James Egleson
Anderson Gwynne, by an instrument in writing under my hand and scal,
should particularly describe and ascertain the nature of the said Invention,
and in what manner the same was to be performed, and cause the same to
be filed in the Great Seal Patent Office within six calendar months next
and immediately after the date of the said Letters Patent.
| NOW KNOW YE, that I, the said James Egleson Anderson Gwynne,
do hereby declare the nature of my said Invention, and in what manner the
same is to be performed, to be particularly described and ascertained in and by
the following statement and accompanying Drawings (that is to say):-
My Invention consists in a new and improved construction of instruments
for indicating the pressure of fluids or gases, such as steam, water, &c., and
also for indicating the amount of vacuum in condensers, &c. When used for
indicating the pressure of steam or gases, I sometimes construct the gauges
with a syphon inside the case that will retain a portion of water, oil, or some
such substance, as a medium for the steam or gases to act upon, and prevent
its return to the boiler or generator, and through which to communicate the
pressure of the steam, gas, &c. The fluid contained in the said syphon has
access to a cylinder or other suitably formed chamber, on the top of which is a
diaphragm or piston of india-rubber, gutta percha, leather properly prepared, or
any suitable material, properly secured, and so constructed that it will move up
and down the distance required without friction or injury to the piston or
diaphragm. I construct the piston in various ways; sometimes attaching the
rod, through which I get my motion to the flexible diaphragm or piston, and
which is made adjustable, so that I can lengthen or shorten it to any point
desired; or I may rest a small pistón or solid plunger, which fits or covers the
top of the said diaphiragin, which is constructed to be capable of adjustment,
aud not attached to the diaphragm, but simply resting upon it. The piston

page_text: rod, whether attached direct to the diaphragm, or to the plunger resting on the
top of it, is attached by a moveable joint to the arm connected with a segment
of a circle; the periphery of the segment has teeth cut in it, into which a
small pinion. is geared; the spindle of the pinion wheel passes through a dial
plate, and carries an indicating hand that is fixed to the spindle, and oscillates
round a properly divided dial, indicating the degrees of pressure:
In another modification, I place a convolute or cylindrically coiled spring
chain, cord, or other suitable flexible attachment round the spindle or axis of
the hand, made fast at one end, with the other end secured to the end of a
rod, beam, or lever, which is attached in a suitable manner to the piston
or diaphragm rod. The action will produce the effect of moving tho hand or
finger round the dial, according to the pressure. A spiral spring is attached
to the arm of the segment insted of the rack segment, which may be variously
fitted and connected; sometimes I employ them shut, and by the pressure they
are opened; at other times I use; them open, and the pressure tends to shut or
close them. I construct a small slide, which can be placed, and made fast at
any part of the arm of said segment, and which keeps the upper end of the
spring steady in its place; another slide at the bottom or lower end of the
spring can also be made fast at any required place, and, by moving the spring
to the proper part of the armn or bar of the segment, I can adjust them to what
amount of pressure I desire. When I want to indicate high pressures, 1
prefer using to or more springs, arranged as above described, as I find the
action more accurate and not so liable to alteration or derangement as one
spring. I coat or cover by electrotype, or otherwise, the springs with metals,
or with any preparation to prevent their oxidation.
The action of the gauge is as follows:-The pressure of the steam, gas, &c.,
acting through the medium of the water, oil, or other fluids contained in the
syphon or body of the instrument, forces up or presses against the diaphragm
or piston, before described. The motion given to the diaphragm or piston is
communicated through the piston rod to the toothed segment, which gear iuto
the pinion, and cause it to rotate, and the indicating hand with it, round the
figured dial, indicating the pressure applied.
In another arrangement, the motion of the bar or lever has a similar
effect on the spring, chain, cord, or other flexible medium used, which causes
it to coil or uncoil and move the hand with it; the distance through which
the indicating hand passes is regulated by the spring, which is made to press
more or less against the piston or diaphragm, or oppose its progress, according
as it is moved backwards and forwards along the arm of the segment.
When used as a vacuum guage I dispense with the syphon altogether, (and.

page_text: this may be done in the construction of the pressure gauge, if desired, pro-
vided an external syphon is used:) I secure the piston rod to the piston or
diaphragm, and attach the other. end of my piston rod to the opposite:or outer
side of the centre ton. which the segment ;oscillates; this gives me the same
motion as in the pressure gauge, but in the arrangements of the vacuum
gauge the action is produced by, the weight of the atmosphere.
In another arrangement, I fix the spring on the upper side of the arm of the
segment; the action is the same as in the pressure gauge, but the..motion is
communicated in an opposite direction, and my arrangements is therefore the
reverse of that used for the pressure gauge.
In the accompanying Drawings,, Figure 2. represents a front elevation of the
pressure gauge; Figs. 1 and 5 represent other arrangements of the pressure
gauge in' section; Figures 3 and 4, represent the arrangement and construction
of my vacuum-gauges. (The same letters refer to the same parts: in all the
Figures.)
Figure 1,shews, one arrangement of my pressure gauge with the syphon
D; C, enclosed in the case. C is a small tube, open at the upper..end, and
enclosed by a larger tube D, closed at the upper end. The passage E, at the
bottom of the outer tube, D, communicates with the chamber F; when this
chamber and passage, together with the outer tube D, is once filled with
water, oil, or other suitable fluid, the inner tube-C prevents its running
away or leaving the outer tube D, unless when the height exceeds the top.
of the tube C. A syphon may also be made surrounding the inner portion of
the outer case, which will answer equally well. G is the flexible piston or
diaphragm, and the piston rod. In Figure 1, the piston rod H is attached
or fastened to the flexible piston or diaphragm. Figure 5 represents the piston
rod unattached, but resting upon the surface or top of the said piston or
diaphragm, the solid plunger or piston Z fitting over or covering the dia-
phragm, and adjusted to the proper length by the screw, as shewn. I, the
centre, on which the segment N rotates; K, the point to which the end of
the piston rod is attached to the arm of the said segment; O, the pinion wheel,
working into the teeth in the circumference of the segment, the pinion carrying
the hand R, placed over a properly divided dial S, S, (Figure 2); M repre-
sents the spiral spring; L, the moveable piece, which slides along the bar or
arm of segment, and keeps the spring in its proper place; Q, the slide, for
securing the other end of the spring. In Figure 2, two springs M, M, are
shewn. Figures 2 and 5 are shewn without any internal syphon. Figure 5
shews the piston rod placed or secured to the other side of the bar or arin of

page_text: segment, and the spring is placed above instead of below the arm or bar; the
spring is also made to close instead of open by the pressure.
In the vacuum gauges, Figures 3 and 4 shews the piston rods H, H, as
secured to the pistons or diaphragms; G, G, Figure 3, shews the piston work-
ing from the opposite or outer side of the centre on which the segment N
rotates; the spring M is placed below, and it opens by the action of the gauge.
In Figure 4 the piston rod is worked from the inner side of the centre of the
segment, and the spring is placed above, and shuts or is compressed by the
action of the gauge of the working parts. Fig. 6 represents another arrange-
ment of the working part of gauge, previously described. Many minor
modifications may be made in the arrangement, which it is unnecessary to
describe.
Haying thus described the nature of my said Invention, I would have it
understood that what I claim is, the construction and arrangement of pressure
and vacuum gauges, as described.
In witness whereof, I, the said James Egleson Anderson Gwynne, have
hereunto set my hand and seal, this Twenty-eight day of May, in the
year of our Lord One thousand eight hundred and fifty-six.
JAMES E. A. GWYNNE. (L.S.)