IMPROVEMENTS IN PRESSURE AND VACUUM GAUGES
Year: 1858

page_text: LETTERS PATENT to Samuel Waite Johnson and James Varley, both of
Peterborough, in the County of Northampton, Engineers, for the Invention
of "IMPROVEMENTS IN PRESSURE AND VACUUM GAUGES."
Sealed the 20th May 1859, and dated the 22nd November 1858.
PROVISIONAL SPECIFICATION left by the said Samuel Waite Johnson
and James Varley at the Office of the Commissioners of Patents, with
their Petition, on the 22nd November 1858.
We, SAMUEL WAITE JOHNSON and JAMES VARLEY, both of Peterborough, in
the County of Northampton, Engineers, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN PRESSURE AND VACUUM GAUGES," to be as
follows:-
Our Invention consists, first, in a new form and means of fitting the spring
pressure disc or plate, which communicates motion through rods, levers, or
otherwise to the pointer used for indicating the pressure or vacuum. We
take a circular plate or disc, and flange or bend up the edge all round till it
forms a right angle, or nearly so, with the flat part or body of the disc. We
then fit this dished or flanged plate truly into a recess, without any other
description of fastening, when to indicate pressure with the flanged edge up-
wards, and in the reverse position to indicate vacuum.
When pressure is
exerted on the bottom or back of the disc, the plate springs or deflects from
the edge of the flange.
The second part of our Iuvention consists in the employment of movable:
figures on a dial plate. By means of these figures the gauge can be adjusted

page_text: without disturbing the dial plate, and a new pressure dise may be applied, and
the figures adjusted to it without any alteration of the dial plate being
required.
The third part of our Invention consists in the adaptation and employment
of an additional or tell-tale pointer, whereby the maximum amount of pressure
exerted can at any time be ascertained. This pointer should be made of some
material, such, for instance, as ivory, horn, or vulcanite, in order to prevent its
being influenced by magnetic attraction. It is so fitted to the spindle of the
ordinary pointer as to yield readily to the power which may be exerted on it
by the ordinary pointer, and yet remain fixed where so moved. We affix or
place a projecting pin on the tell-tale pointer in such manner that on the
ordinary pointer coming in contact with it, the tell-tale shall be driven
forward.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed.
by the said Samuel Waite Johnson and James Varley in the Great
Seal Patent Office on the 21st May 1859.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, SAMUEL
WAITE JOHNSON and JAMES VARLEY, both of Peterborough, in the County of
Northampton, Engineers, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-second day of November, 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
us, the said Samuel Waite Johnson and James Varley, Her special licence
that we, the said Samuel Waite Johnson and James Varley, our executors,
administrators, and assigns, or such others as we, the said Samuel Waite
Johnson and James Varley, our 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 "IMPROVE-
MENTS IN PRESSURE AND VACUUM GAUGES," upon the condition (amongst others)
that we, the said Samuel Waite Johnson and James Varley, or one of us, our
executors or administrators, by an instrument in writing under our, or their,
or one of our or their hands and seals, should particularly describe and
ascertain the nature of the said Invention, and in what manner the same

page_text: 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 we, the said Samuel Waite Johnson and James
Varley, do hereby declare the nature of our 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, reference being had to the Drawings
hereunto annexed, that is to say:-
Our Invention consists, first, in a new form and means of fitting the spring
pressure disc or plate, which communicates motion through rods, levers, or
otherwise to the pointer used for indicating the pressure or vacuum. We
take a circular plate or disc, and flange or bend up the edge all round till it
forms a right angle, or nearly so, with the flat part or body of the disc. We
then fit this dished or flanged plate truly into a recess, without any other
description of fastening, when to indicate pressure with the flanged edge
upwards, and in the reverse position to indicate vacuum. When pressure is
exerted on the bottom or back of the disc, the plate springs or deflects from
the edge of the flange.
The second part of our Invention consists in the employment of movable
figures on a dial plate. By means of these figures the gauge can be adjusted
without disturbing the dial plate, and a new pressure disc may be applied,
and the figures adjusted to it without any alteration of the dial plate being
required.
Figure 1 is a front elevation, and Figure 2 a cross section, of a gauge
adapted for low pressure made according to our Invention. A, A, A, is an
outer case; the recess a forms a receiving box for the flanged spring disc B,
the flanged edges of which rest against the sides of the box, but are in no way
tied thereto; b is a disc of india-rubber placed over the back of the spring disc;
C is a nut, with a recess in the upper part thereof, screwed into the casing A;
c is an opening through the nut C, communicating with the steam or other
fluid, the pressure of which is to be indicated; D is a rod adjustable by a set
screw d; the bottom of the rod rests upon the spring disc B, while the upper
end comes in contact with an excentric or tumbler E on a spindle F; G is a
needle or pointer affixed to the spindle F; and H is an additional pointer to
shew the maximum pressure attained. We make no claim, however, to the
employment of this additional pointer as an Invention of our own. I, I, I, are
the movable figures placed on the front of the case A; each figure is formed
in a separate piece. Over the foot of the figures we place an india-rubber
washer J, and secure them by a brass ring K, screwed on to the front of the

page_text: case.
Upon pressure being exerted on the under side of the spring disc, it
plays upon its extreme edge, and pushing up the rod D, causes the needle to
indicate the degree of pressure.
Figure 3 is a front elevation, and Figures 4 and 5 cross sections, of a gauge
adapted for high pressure; Figure 6 is a plan on a reduced scale at back of
the dial plate. A is the case; B is the flanged spring disc'; over this disc is
placed a disc of india-rubber, firmly secured between the flange of the disc
frame C and the back of the case A, so as to form an air-tight joint. In con-
tact with the spring or pressure disc B is an eccentric or tumbler D, secured
by a set screw upon the spindle of the toothed sector E; the sector gears
with the pinion F, the spindle of which passes through the dial plate G, and
carries the index needle or pointer H; I, I, I, are the movable figures held
down upon the dial plate by the brass ring J and screws j,j; K is a silk
thread which passes round a small pulley upon the spindle of the pinion F, and
is connected to a light spring M for the purpose of preventing a tremulous
N is a chamber at
motion of the pointer, and causing it to return to zero.
the back of the spring disc, communicating with the steam or other fluid, the
pressure of which is to be indicated.
The action of this gauge is as follows:-When pressure is excrted upon the
disc B, it plays upon or deflects from its extreme edge, the greatest amount of
deflection is given out at the centre where it acts upon the excentric or tumbler
D, and causes the sector and pinion to move about their centres and carry
round the index needle or pointer H.
And having now described the nature of our said Invention, and in what
manner the same is to be performed, we declare that we claim as our im-
provements in pressure and vacuum gauges, first, the employment of a spring
pressure plate formed and fitted in manner and for the purposes herein-before
described.
And, second, the employment of movable figures on the dial plate, as
herein-before described.
In witness whereof, we, the said Samuel Waite Johnson and James
Varley, have hereunto set our hands and seals, this Nineteenth day of
May, One thousand eight hundred and fifty-nine.
SAMUEL WAITE JOHNSON. (L.S.)