IMPROVEMENTS IN PRESSURE. GUAGES
Year: 1855

page_text: LETTERS PATENT to Thomas Rickett, of Stony Stratford, in the County of
Buckingham, Engineer, for the Invention of "IMPROVEMENTS IN PRESSURE.
GUAGES."
Sealed the 15th February 1856, and dated the 12th December 1855.
PROVISIONAL SPECIFICATION left by the said Thomas Rickett at the
Office of the Commissioners. of Patents, with his Petition, on the 12th
December 1855.
I, THOMAS RICKETT, of Stony Stratford, in the County of Buckingham,
Engineer, do hereby declare the nature of the Invention for "IMPROVEMENTS
IN PRESSURE GUAGES" to be as follows:-
This Invention has for its object a more advantageous combination of the.
parts of a pressure guage than heretofore, when using mercury' or a fluid as
the means of indicating the pressure. For this purpose two pistons or surfaces
of different area are combined together, and the steam or other fluid is caused
to press on a comparatively small area of a piston or surface, and the mercury
or other fluid used for guaging or indicating the pressure is caused to press on
a comparatively large area of piston or surface, by which, the height of the
measuring column. may be greatly reduced. It is preferred to employ two
pistons composed of metal and vulcanized india-rubber, but. the construction
of the pistons or surfaces on which the respective fluids press may be varied.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Thomas Rickett in the Great Seal Patent Office on the
11th June 1856.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
RICKETT, of Stony Stratford, in the County of Buckingham, Engineer, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twelfth day of December, 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 Thomas Rickett, Her special licence that I, the said Thomas Rickett, my
executors, administrators, and assigns, or such others as I, the said Thomas
Rickett, 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 PRESSURE
GUAGES," upon the condition, amongst others, that I, the said Thomas Rickett,
my executors or administrators, by an instrument in writing under my, or
their, or one of their hands and seals, should particularly describe and ascer-
tain 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 Thomas Rickett, 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 a more advantageous combination of the
parts of a pressure guage than heretofore, when using mercury or a fluid
as the means of indicating the pressure. For this purpose two pistons or
surfaces of different area are combined together, and the steam or other fluid
is caused to press ön a comparatively small area of a piston or surface, and
the mercury or other fluid used for guaging or indicating the pressure is
caused to press on a comparatively large area of piston or surface, by which
the height of the measuring column may be greatly reduced. It is preferred
to employ two pistons composed of metal and vulcanized india-rubber, but the

page_text: construction of the pistons or surfaces on which the respective fluids press
may be varied.
Having thus stated the nature of my said Invention, I will proceed more
fully to describe the manner of performing the same.
DESCRIPTION OF THE DRAWING.
Figure 1 is a vertical section of the guage; Figure 2 is a front elevation;
Figure 3 is a plan. a is the larger piston, the joint of which is made with a
disc or diaphragm of vulcanized india-rubber or other suitable flexible material,
secured to the piston by a nut and washer or plate. The exterior edge of the
diaphragm makes the joint between the chamber or case 6 above and the
seat c below; d is a glass tube, which is fixed to the upper part of the chamber
or case b, and communicates with it; the other end of the tube is open to the
atmosphere. The space between the piston a and the chamber or case 6 is
filled with mercury. e is the smaller piston, on which the steam or other fluid
presses; a diaphragm of waterproof fabric, as is shown, forms the joint
between this piston and the outer case f. A syphon tube g communicates
with the boiler or other vessel. In action, the steam or water in the tube g
presses on the piston e (which is connected with the piston a), and the piston
a forces the mercury contained in the chamber 6 up the glass tube d, until the
pressure of the column of mercury on the area of piston a counterbalances
the pressure of steam or other fluid on the piston e. A graduated plate is
fixed on the side of the glass tube, which indicates the pressure.
Having thus described the nature. of my said Invention, and the manner of
performing the same, I would have it understood that I make no claim to
the parts separately, and the forms of the parts may be varied without
departing from my Invention; but what I claim is, the combination of
pistons of different sizes acting with the other parts, and producing a pressure
guage, as herein described.
In witness whereof, I, the said Thomas Rickett, have hereunto set my
hand and seal, this Tenth day of June, in the year of our Lord One
thousand eight hundred and fifty-six.
Witness,
THOMAS RICKETT. (L.S.)
HENRY W. CARPMAEL.