IMPROVEMENTS IN THE CONSTRUCTION OF STEAM AND VACUUM GAUGES
Year: 1863

page_text: LETTERS PATENT to George Murdoch, of Portsmouth, in the County of
Hants, for the Invention of "IMPROVEMENTS IN THE CONSTRUCTION OF
STEAM AND VACUUM GAUGES."
Sealed the 12th January 1864, and dated the 18th July 1863.
PROVISIONAL SPECIFICATION left by the said George Murdoch at the
Office of the Commissioners of Patents, with his Petition, on the 18th
July 1868.
I, GEORGE MURDOCH, of Portsmouth, in the County of Hants, do hereby
i declare the nature of the Invention for." IMPROVEMENTS IN THE CONSTRUCTION
OF STEAM AND VACUUM GAUGES," to be as follows:—
This Invention has for its object improvements in the construction of steam
and vacuum gauges, in which cheapness and simplicity are combined with
great certainty of action. For this purpose I form a metal chamber of suitable
shape, which forms a portion of a box or receptacle hereafter described.
The upper part of this chamber carries a glass tube and index for indicating
the pressure or vacuum, and a metallic guard for securing and protecting the
same. The lower part of the metal chamber is recessed, and is filled with
mercury, a diaphragm of steel or other suitable metal, either plain or corrugated,
is placed on the flat surface of the chamber, which is filled with mercury and
is securely held in this position by a metallic disc screwed to the metal picco
forming the mercury chamber. This metallic disc is recessed so as to form a

page_text: corresponding chamber to that containing mercury. This latter chamber is
kept full of oil or distilled water, and is capable of being placed in communi-
cation with the steam or other pressure or vacuum to be indicated by means of
suitable pipes and stop-cocks. Within the glass tube a taper metallic rod is
placed, and is held in position by a suitable spring, and has for its object the
counteraction of the unequal displacement of the mercury. The steam or
other pressure acting upon the oil or distilled water presses upon the diaphragm
and forces the mercury up the tube. When used as a vacuum gauge, the
part containing the oil is placed in communication with the atmosphere by
opening suitable cocks and pipes, whilst the mercury tube is placed in com-
mmunication with the vacuum by other suitable cocks and pipes, so that when
required the instrument can be readily arranged to act as a pressure gauge,
vacuum gauge, or steam and vacuum gauge combined, showing the full
pressure acting on the piston.
With non-condensing engines, gauges so constructed can be arranged to
indicato the back pressure on the piston. Owing to the simplicity of con-
struction and arrangement of the parts, gauges constructed according to my
Invention can be readily repaired if damaged or deranged.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Georgo Murdoch in the Great Seal Patent Office on the 18th
January 1864.
TO ALL TO WHOM THESE PRESENTS SHALL COME, J, GEORGE
MURDOCH, of Portsmouth, in the County of Hants, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eighteenth day of July, in the year of our Lord One
thousand eight hundred and sixty-three, in the twenty-seventh year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
George Murdoch, Iler special licence that I, the said George Murdoch, my
executors, administrators, and assigns, or such others as I, the said George
Murdoch, my executors, administrators, 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 THE CONSTRUCTION
OF STEAM AND VACUUM GAUGES," upon the condition (amongst others) that I,
the said George Murdoch, my executors or administrators, by an instrument

page_text: 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 imme-
diately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said George Murdoch, do hereby declare
the nature of the said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement thereof, that is to say :—
This Invention has for its object improvements in the construction of steam
and vacuum gauges, in which cheapness and simplicity are combined with
great certainty of action. For this purpose I form a metal chamber of suitable
shape, which forms a portion of a box or receptacle hereafter described. The
upper part of this chamber carries a glass tube and index for indicating tho
pressure or vacuum, and a metallic guard for securing and protecting the
same. The lower part of the metal chamber is recessed, and is filled with
mercury, a diaphragm of steel or other suitable metal, either plain or corru-
gated, is placed on the flat surface of the chamber, which is filled with mercury,
and is securely held in this position by a metallic disc screwed to the metal
piece forming the mercury chamber. This metallic disc is recessed so as to
form a corresponding chamber to that containing mercury. This latter
chamber is kept full of oil or distilled water, and is capable of being placed in
communication with the steam or other pressure or vacuum to be indicated by
means of suitable pipes and stop-cocks. Within the glass tube a taper metallic
rod is placed, and is held in position by a suitable spring, and has for its object
the counteraction of the unequal displacement of the mercury. The steam or
other pressure acting upon the oil or distilled water presses upon the diaphragm,
and forces the mercury up the tube. When used as a vacuum gauge, the
part containing the oil is placed in communication with the atmosphere by
opening suitable cocks and pipes, whilst the mercury tube is placed in com-
munication with the vacuum by other suitable cocks and pipes, so that when
required the instrument can be readily arranged to act as a pressure gauge,
vacuum gauge, or steam and vacuum gauge combined, shewing the full
pressure acting on the piston.
With non-condensing engines, gauges so constructed can be arranged to
indicate the back pressure on the piston. Owing to the simplicity of con-
struction and arrangement of the parts, gauges constructed according to my
Invention can be readily repaired if damaged or deranged.
And in order that my Invention may be most fully understood and readily

page_text: DESCRIPTION OF THE DRAWING.
Figure 1 shows a vertical section, and Figure 2 a front elevation of a steam
and vacuum gaugo constructed according to my Invention.
A is a chamber (filled with mercury) formed between the steel plate or
diaphragm A and the hollow metal plate or disc A²; B is another chamber
formed on the other side of the diaphragm A' between it and the metal plato
or disc E, which is fixed by screws or otherwise to the disc A, the diaphragm
being firmly secured between the two, as shewn in the Drawing. The
chamber B is filled with oil or distilled water. C is a two-way cock, the
pipe or passage C₁ opening to the atmosphere and to the chamber B, and the
pipo or passage C³ being in communication with the steam pipe and chamber B;
D is a glass tube mounted within the metal guard F upon which the index is
marked for indicating the pressure or vacuum. The lower end of the glass
tube D is connected to the mercury chamber A, from which the mercury rises
into the tube around the taper metal rod H supported within the tube D, and
retained in position by the screwed upper end I, or by a spiral spring around
the upper end to counteract the unequal displacement of the mercury; G is a
two-way cock, the passage 9¹ opening to the atmosphere, and the passage g³ to
the condenser.
Having thus described the nature of my Invention, I would have it under-
stood that I do not confine myself to the exact details herein shewn and
described, so long as the peculiar character of my Invention be retained; but
what I claim is the construction of steam and vacuum gauges, as herein
described.
In witness whereof, 1, the said George Murdoch, have hereunto set my
hand and seal, this Sixteenth day of January, in the year of our
Lord One thousand eight hundred and sixty-four.
G. MURDOCH. (LS).

page_text: Achamber formed between a Steel diaphragm
and an Iron disc and filled with Mercury.
A chamber formed between the Steel diaphragm
and disc E'and filled with oil or distilled water
A two way cock "C" opening to the atmosphere
and chamber Bleading to the steam
pipe and chamber B
Aglass tube united with the Mercury chamber
Abrass disc forming with the Steel diaphragm
the chamber B.
A brass guard for securing glass tube in position
Atwo way cock.g'opening to the atmosphere g²
leading to the Condenser.
An iron rod within the glass tube D.D. for
counteracting unequal displacement.
A common screw for keeping iron rod H´in
position.