IMPROVEMENTS IN INSTRUMENTS FOR MEASURING FLUID OR OTHER PRESSURE OR WEIGHT
Year: 1870

page_text: LETTERS PATENT to Frédérick Foster, of Lansdowne Cottages;
No. 316, Essex Road, Islington, in the County of Middlesex, for
the Invention of "IMPROVEMENTS IN INSTRUMENTS FOR MEASURING FLUID
OR OTHER PRESSURE OR WEIGHT."
.
Sealed the 22nd February 1870, and dated the 3rd January 1870.
PROVISIONAL SPECIFICATION left by the said Frederick Foster at.
" the Office of the Commissioners of Patents, with his Petition, on
the 3rd January 1870.
I, FREDERICK FOSTER, of Lansdowne Cottages, No. 316, Essex Road,
Islington, in the County of Middlesex, do hereby declare the nature of
the said Invention for "IMPROVEMENTS IN INSTRUMENTS FOR MEASURING FLUID
OR OTHER PRESSURE OR WEIGHT," to be as follows:-
.
One of the objects of this Invention is the construction.of pressure.
gauges of small size and readily portable and capable of being adapted
at once and without trouble to any boiler provided with ordinary boiler
fittings: The instrument consists of a small chamber, to which steam
(or it may be other fluid of which the pressure is to be measured) can

page_text: be admitted. This chamber is capable of being connected with the
boiler or other vessel containing the fluid by a screw coupling, and
couplings of various sizes are provided, one or other of which will suit any
ordinary pressure gauge nozzle. One side of the chamber above mentioned
is closed by a flexible diaphragm of india-rubber or similar material
supported by a flat or nearly flat spiral spring so that the diaphragm
cannot yield to the pressure without deflecting the spring. This spring
is mounted parallel to the face or dial of the instrument, and carries a
pin with a screw of a rapid pitch cut upon it. This screw works with a
nut supported by the dial plate but able to turn freely, and the
indicating hand is mounted upon this nut. It will then be seen that
any deflection of the spiral spring resulting from the pressure will cause
a partial rotation of the nut, and so the indicating hand will be caused to
move through an angle proportional to the pressure. It is obvious that
in place of mounting the nut on the dial, and the screw upon the spring,
the arrangement in these respects may be reversed; or motion may be
communicated from the spring to the dial by a link passing in an
inclined direction to a rack so mounted as to be able to move
longitudinally in a direction parallel to the plane of the dial and of the
spring, and the index hand then has a pinion upon it gearing with this
rack or the link from the spring may be connected with a curved
rack mounted on a centre or axis, in which case the deflection of the
spring will cause the rack to move around its centre and to actuate the
pinion on the index hand. In other ways the flat or nearly flat spiral
spring supporting the flexible diaphragm may be caused to work an
index on a dial parallel to the said diaphragm and spring, and the
arrangement is applicable to fixed as well as to portable gauges.
The methods above described for giving motion from a diaphragm to
an index hand on a dial parallel to such diaphragm are applicable where
flat or nearly flat spiral springs are not used. They are also applicable
in the construction of weighing machines.. A flat or nearly flat spiral
spring is for this purpose mounted horizontally, and a platform on which
the body to be weighed is placed is supported from its centre, and the
deflection of the spring so produced is caused to give motion to the
index hand in one or other of the ways already described. ·
་་

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Frederick Foster in the Great Seal Patent Office
on the 2nd July 1870.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, FREDERICK
FOSTER, of Lansdowne Cottages, No. 316, Essex Road, Islington, in the
County of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Third day of January, in the year of
our Lord One thousand eight hundred and seventy, in the thirty-third
year of Her reign, did, for Herself, Her heirs and successors,
give and
grant unto me, the said Frederick Foster, Her special licence that I,
the said Frederick Foster, my executors, administrators, and assigns, or
such others as I, the said Frederick Foster, 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 INSTRUMENTS FOR
MEASURING FLUID OR OTHER PRESSURE OR WEIGHT," upon the condition
(amongst others) that I, the said Frederick Foster, 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.
NOW KNOW YE, that I, the said Frederick Foster, 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:—
One of the objects of this Invention is the construction of pressure
gauges of small size and readily portable and capable of being adapted
at once and without trouble to any boiler provided with ordinary boiler
fittings. The instrument consists of a small chamber, to which steam
(or it may be other fluid of which the pressure is to measured); can
bc admitted. This chamber is capable of being connected, with the

page_text: boiler or other vessel containing the fluid by a screw coupling, and
couplings of various sizes are provided, one or other of which will suit
any ordinary pressure gauge nozzle. One side of the chamber above
mentioned is closed by a flexible diaphragm of india-rubber or similar
material supported by a flat or nearly flat spiral spring, so that the
diaphragin cannot yield to the pressure without deflecting the spring.
This spring is mounted parallel to the face or dial of the instrument,
and carries a pin or nut which works with a screw of a rapid pitch
supported by the dial plate but able to turn freely, and the indicating
hand is mounted upon this screw. It will then be seen that any
deflection of the spiral spring resulting from the pressure will cause a
partial rotation of 'the screw, and so the indicating hand will be caused
to move through an angle proportional to the pressue. It is obvious
that in place of mounting the screw on the dial and the pin or nut upon
the spring the arrangement in these respects may be reversed; or
motion may be communicated from the spring to the dial by a link
passing in an inclined direction to a rack so mounted as to be able to
move longitudinally in a direction parallel to the plane of the dial and
of the spring, and the index hand then has a pinion upon it gearing
with this rack; or the link from the spring may be connected with a
curved rack mounted on a centre or axis, in which case the deflection
of the spring will cause the rack to move around its centre and to
actuate the pinion on the index hand. In other ways the flat or nearly
flat spiral spring supporting the flexible diaphragm may be caused to
work-an-index on a dial parallel to the said diaphragm and spring, and
the arrangement is applicable to fixed as well as portable gauges.
The methods above described for giving motion from a diaphragm to
an index hand on a dial parallel to such diaphragm are also applicable
were flat or nearly flat spiral springs are not used. They are also
applicable in the construction of weighing machines. For this purpose
a platform on which the body to be weighed is placed is supported
horizontally on a flat or nearly flat spiral spring, or is otherwise
supported horizontally on springs, and the. deflection of the spring or
springs so, produced is caused to give motion to the index hand in one.
or other of the ways already described.
Figure 1 of the Drawings hereunto annexed shews a transverse
section, and Figure 2. a front view of a pressure gauge constructed as.

page_text: herein-before described, in which the spring is caused to work the index
hand by a quick threaded screw and a pin working into the thread of
the screw.
In this Figure a is the chamber, into which steam or other fluid whose
pressure is to be ascertained is admitted; 6 is a screw socket to screw
on to an ordinary pressure gauge nozzle of a boiler or vessel containing
fluid under pressure. Screw couplings of various sizes may be provided
to suit the various sizes of pressure gauge nozzles ordinarily employed.
c is the flexible diaphragm forming one side of the chamber a. This
diaphragm is held between the chamber a and a cylindrical chamber d
screwed to it, as shown. e is the spring by which the central portion of
the diaphragm is supported. The outer coil of this spring rests, in a
recess in the chamber d, and the innermost coil of the spring has
soldered to it a tube. f. The end of this tube carries a pin g, which
passes through a slot cut spirally in the pin h; one end of this screw pin
passes through a hole in the end of the chamber d and forms the axis.
of the index hand; the opposite end of the screw pin turns in a
bearing at the end of a tube which projects from the end of the
chamber d. The tube / fits within the tube f, and slots are formed in the
two opposite sides of the tube for the pin h to pass through, as shewn
in the enlarged section Figure 3, taken through the line A, B, Figure 1.
When the spring is deflected by any pressure exerted on the diaphragm,
the pin causes the screw pin h to turn, and so turns the index hand.
m is the dial plate fixed to the exterior of the chamber d, and na
glass for covering the same. This glass is carried by a cylindrical
casing o, as shown.
5.
Figures 4, 5, and 6 shew' respectively a back view, a section, and a
front view (with the dial plate removed) of a pressure gauge similar to.
that above described, except that the diaphragm c is formed of corru..
gated sheet metal, and is supported by three or more springs of different
construction to that shewn at Figure 1. The springs rest against three
radial arms m', which come just behind the dial plate m. The tube f
is carried by the centre of the diaphragm, and gives motion to the index
hand in the same manner as that shewn in Figure 1. -
.
The other parts of this apparatus which are similar to those shewn at
Figure 1, are marked with the same letters of reference, so that it is
unnecessary again to describe them.

page_text: "
At Figure 7 is shewn a section of a gauge in which motion is com-
municated from the spring e to the dial by a link passing in an inclined
direction to a rack. The spring e is similar to that shewn at Figure 1,
and has soldered to it at its centre a small piece of metal to which the
link n' is pin jointed; the other end of this link is pin jointed to the
rack o', which at its ends is formed to slide in guides p. When the
spring is deflected by any pressure exerted on the diaphragm c the link
causes the rack to slide in its guides and so causes the pinion, which
gears with the rack to revolve. The pinion r is fast on the axis of the
index, so that the index turns with it and indicates the pressure exerted
against the diaphragm.
In the arrangement shown at Figure 8 the link n¹ is jointed to a
toothed arc o¹, which when the spring e is deflected is caused to turn on
its axis o², and by so doing causes the pinion r on the axis of the index
hand to revolve.
Figures 9, 10, and 11 shew respectively a plan view, a side view, and
a vertical section of a weighing machine constructed according to my
Invention.
... الدني
+
a is a platform on to which the weight to be weighed is placed; b, b,
are springs by which this platform is supported; è is a tube projecting 2
downwards from the centre of this platform; the lower end of the tube
carries a pin which works into the quick threaded screw e on the axis of
the index hand f. When a weight is placed on the platform the springs b
are compressed, and the index hand is caused to turn and indicate the
weight on the scale 9.
A
Having thus described the nature of my Invention, and the manner
of performing the same, I would have it understood that what I claim
is,
17709
t
"
First. The construction of pressure gauges with an elastic diaphragmi
supported by a spring or springs and placed parallel to the dial plate. 3
Second. The combinations of mechanism herein described and shewn
at Figures 1, 5, 7, and 8 of the Drawings hereunto annexed for trans-

page_text: Third. The construction of weighing machines, substantially as herein
described.
In witness whereof, I, the said Frederick Foster, have hereunto
set my hand and seal, this Second day of July, in the year of our
Lord One thousand eight hundred and seventy.
FRED³. FOSTER. (L.S.)