AN IMPROVED PRESSURE GAUGE FOR STEAM, GAS, OR OTHER FLUIDS
Year: 1858

page_text: LETTERS PATENT to Thomas Paramore Purssglove, of Battersea, in the
County of Surrey, for the Invention of "AN IMPROVED PRESSURE GAUGE FOR
STEAM, GAS, OR OTHER FLUIDS."
Sealed the 31st May 1859, and dated the 1st December 1858.
PROVISIONAL SPECIFICATION left by the said Thomas Paramore
Purssglove at the Office of the Commissioners of Patents, with his
Petition, on the 1st December 1858.
I, THOMAS PARAMORE PURSSGLOVE, of Battersea, in the County of Surrey,
do hereby declare the nature of the said Invention for "AN IMPROVED PRESSURE
GUAGE FOR STEAM, GAS, OR OTHER FLUIDS," to be as follows:-
When it has been required to gauge high pressures, the instrument known
as the mercury gauge has been either elongated to an inconvenient height or
has had to be superseded by some of the ordinary pressure gauges. These
pressure gauges being open to serious objection on account of their liability
to get out of order, and the mercury gauge being the most correct and
satisfactory in its indications, has suggested the following arrangement. or
Invention.
My Invention consists of an arrangement of a series of pairs of tubes, each
pair forming in itself a mercury gauge similar to the one commonly known as
such. For the purpose of registering pressures and of obtaining an instrument
of a convenient or portable form, I take a number of tubes, placing them side
by side in a vertical position, and connecting them together at the bottom and
top alternately, so as to form a continuous pipe. Into this pipe I pour.

page_text: mercury until it rises in each leg to half the vertical height thereof; having
done this, I fill up the remaining space in each one with water or any other
fluid. I attach one end of this pipe to the boiler or other vessel, whose
pressure it is required to ascertain, and to the other end of the pipe I attach
a graduated scale to register the pressure by the rise and fall of the mercury
in the last leg.
Upon the pressure being turned on, it will be found that as the mercury in
the first leg is depressed and forced into the next in communication, so will
the mercury in every alternate leg be depressed, owing to the intervention of
the water or other fluid. These columns thus arranged will have the same
effect as if they formed one vertical column of mercury equal to the sum of
their heights minus the sum of the water pressure.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Thomas Paramore Purssglove in the Great Seal Patent Office
on the 1st June 1859.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
PARAMORE PURSSGLOVE, of Battersea, in the County of Surrey, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the First day of December, in the year of our Lord
One thousand eight hundred and fifty-eight, in the twenty-second year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Thomas Paramore Purssglove, Her special licence that I, the said
Thomas Paramore Purssglove, my executors, administrators, and assigns, or
such others as I, the said Thomas Paramore Purssglove, my executors, admi-
nistrators; 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 King-
dom of Great Britain and Ireland, the Channel Islands, and Isle of Man,
an Invention for "AN IMPROVED PRESSURE GAUGE FOR STEAM, GAS, OR OTHER
FLUIDS," upon the condition (amongst others) that I, the said Thomas Paramore
Purssglove, my executors or administrators, by an instrument in writing under
my, or their, or one of their hands and seals, 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.

page_text: NOW KNOW YE, that I, the said Thomas Paramore Purssglove, 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 in writing and on reference to the accompanying
Drawings, that is to say :-
My Invention of "an improved pressure gauge for steam, gas, or other
fluids, is intended to render the mercury gauge "available for registering
high pressures. Hitherto, when it has been required to gauge high pressures,
the mercury gauge has either been elongated to an inconvenient height or has
had to be superseded by the use of some of the ordinary pressure gauges ;
these pressure gauges being open to serious objection on account of their
liability to get out of order, and the mercury gauge being well known to be
the most correct and satisfactory in its indications has suggested to me the
Invention of the following, arrangement.
My Invention consists principally in the arrangement of a series of pairs of
tubes, each pair forming in itself a mercury gauge similar to the one commonly
known as such. For the purpose of registering high pressures and of obtain-
ing an instrument of a convenient and portable form, I take a number of
tubes, placing them side by side in a vertical position and connecting them
together at the top and bottom alternately, so as to form a continuous pipe.
Into this pipe I pour mercury, until it rises in each leg to about half its
vertical height; having done this, I fill up the remaining space in each leg
with water, spirit, or any other incompressible fluid. I connect the first leg
of the pressure gauge so formed to the boiler or other vessel whose pressure
it is required to gauge, and behind the last leg of the gauge (which should be
made of glass) I place a graduated scale to register the pressure by the rise
or fall of the mercury in the same. Upon the pressure being turned on, it
will be found that as the mercury in the first leg is depressed and forced into
the next in communication, so will the mercury in every alternate leg be
depressed, owing to the intervention of the water, spirit, or other fluid; such
fluid acting as a communicator of pressure from the one column of mercury
to the next in order, and so on, in succession; and these columns, thus
arranged, will have the same effect as if they formed one continuous vertical
column of mercury.
I would here remark that if a small bulb or other enlargement is made
near the bottom of each alternate leg, such bulb being of a capacity to contain
sufficient mercury to fill the leg in communication with it, a much greater
range will be obtained, nearly the whole height of the vertical tube being thus
made available for registering the pressure. And in order that the point

page_text: marked "zero
on the graduated scale may at all times be opposite to the
level of the mercury when the pressure is off, notwithstanding any alteration in
the said level caused by variations in temperature, I make the said graduated
scale or index moveable, and attach the same to a float resting on the surface
of a sufficient quantity of mercury, placed in a separate vessel for that purpose;
so that any rise or fall of the level of the mercury in the gauge itself, due to
temperature only and not to pressure, is compensated by a corresponding rise
or fall of the graduated scale or index.
The practical construction and application of my Invention will be better
understood on reference to the accompanying Drawings, figures and letters of
reference being marked thereon, corresponding with those in the following
explanation thereof.
Figure 1 shews an external front elevation of my improved pressure gauge;
Figure 2 is a vertical section taken transversely through the last leg and the
compensating apparatus, and Figure 3 is a similar section taken through the
centre of the tubes.
The gauge is formed of four pairs of tubes a, a, a, a, connected together
alternately at the top and bottom by the passages b, b, b, b, so as to form one
continuous serpentine tube; these tubes are all made of metal with the
exception of the last one a", which is made of glass. c, c, is the graduated
scale or index plate. It will be evident that if the first tube a¹ be connected
to a steam boiler (or other vessel whose pressure it is required to register),
as soon as the communication is opened, the mercury will be depressed in the
first leg a¹, causing a corresponding rise of the mercury in the second leg (as in
the ordinary mercury gauge), and that this movement will be transmitted to
the last leg a, through the medium of the intervening water or spirit and
mercury in the other tubes, and indicated by the graduated scale c; the sum
of the mercury displaced in the several tubes being equal to the pressure on
the surface of the mercury in the first leg.
If the temperature of the atmosphere where the gauge is fixed would always
remain about equal, the index c might be fixed, but if the gauge be subject
to such variations of temperature as to cause any material alteration in the
level of the mercury in the gauge when at rest, the index should be moveable,
and may either be set by hand before the pressure is turned on, or it may be
made self-acting by the following means:-The index c is carried by links d, d,
attached thereto and to the back of the gauge, and the upper link is connected
to a rod e, e, carrying at its lower end a float f, resting on the surface of the
mercury in the short tube g, fixed in the top of the vessel h, h, which vessel
contains half as much mercury as is contained in the gauge. The conseqence

page_text: of this arrangement is that as any increase of temperature causes the level of
the mercury in the gauge to rise, the same effect will be produced on the
index, and vice versa, so that the level of the mercury in the gauge and the
point "zero" of the index always correspond before the pressure is turned on.
The vessel i at the top of the tube g is for the purpose of preventing any
waste of mercury if the gauge should be inverted, and the vessel k at the top
of the last leg a" is for the same purpose.
Having now described the nature and object of my said Invention for "An
Improved Pressure Gauge for Steam, Gas, or other Fluids," together with the
manner of carrying the same into practical effect, I would remark in con-
clusion that I claim as my Invention the general construction and arrangement
of the pressure gauge, as exhibited in the annexed Drawings and above
described, or any mere modification of the same or any part thereof whereby
the same end may be obtained.
In witness whereof, I, the said Thomas Paramore Purssglove, have here-
unto set my hand and seal, this Thirty-first day of May, in the year of
our Lord One thousand eight hundred and fifty-nine.
T. P. PURSSGLOVE. (L.S.)