IMPROVEMENTS IN PRESSURE GAUGES
Year: 1858

page_text: LETTERS PATENT to James Fogg, of Great Lever, near Bolton, in the
County of Lancaster, Book-keeper, for the Invention of "IMPROVEMENTS
IN PRESSURE GAUGES."
Sealed the 1st February 1859, and dated the 12th August 1858.
PROVISIONAL SPECIFICATION left by the said James Fogg, at the
Office of the Commissioners of Patents, with his Petition, on the
12th August 1858.
I, JAMES FOGG, of Great Lever, near Bolton, in the County of Lancaster,
Book-keeper, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN PRESSURE GAUGES," to be as follows:-
Instead of allowing the steam or other elastic fluid to come in contact
directly with the mercury as at present adopted in the ordinary mercurial
gauge, I allow it to press upon a piston or plunger of a small area, either
with or without the intervention of an elastic disc, the upper part of the said
piston which presses against the mercury through the intervention of an
elastic disc being of a larger area. The difference in the areas of the two
surfaces produces the important effect of enabling a short column of mercury
to balance the steam or other elastic fluid. The differences between the
heights of the ordinary gauges and my improved gauge being in proportion
to the differences of the areas of the pistons, I employ a tube of a small

page_text: diameter, and connect it with a scale in order to indicate the pressure. By
the foregoing means I produce an improved mercurial pressure gauge of great
simplicity and portability.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said James Fogg in the Great Seal Patent Office on the 11th
February 1859.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
FOGG, of Great Lever, near Bolton, in the County of Lancaster, Book-keeper,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twelfth day of August, 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 James Fogg, Her special licence that I, the said James Fogg,
my executors, administrators, and assigns, or such others as I, the said
James Fogg, 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 "IMPROVE-
MENTS IN PRESSURE GAUGES," upon the condition (amongst others) that I, the
said James Fogg, by an instrument in writing under my hand and seal,
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 James Fogg, 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 (that is to say):-
Instead of allowing the fluid or other body, the pressure or weight of
which is to be indicated, to come into direct and immediate contact with the
mercury or other fluid, by means of whose vertical height or gravitation the
pressure is to be indicated, as is now adopted in the common mercurial and
other guages, I interpose a moveable piston or plug made of metal or other
suitable material between such pressure or weight and the fluid used for

page_text: indicating the areas or superficies of the ends or other parts of such plug being
made of such proportion to one another as it may be desired to decrease or
increase the length or height of the indicating column, whether the same be
of mercury or other fluid, below or above its natural height. When it is
wished to decrease the length of the natural column of indicating fluid, I make
the end of the plug on which the pressure is brought to bear of a lesser area
than its other end, against which the indicating fluid is brought to bear, these
areas having the same proportion to each other as the desired length of
indicating column bas to its natural column, being the height to which the,
fluid would rise in a tube if the pressure came into immediate contact with it.
When it is desired to increase the length or height of the natural column of
indicating fluid, I make the end of the plug upon which the pressure is
brought to bear of a greater area than its other end, against which the
indicating fluid is brought to bear. For indicating either very light or very
heavy pressures or weights, I may employ a series of two or more of these
plugs so arranged that the pressure or weight desired to be indicated comes
upon the first plug of the series, and is by it transmitted proportionately,
according to the areas of its ends, through the agency of a fluid in an increased
or decreased pressure upon the end of the second plug of the series, which
may again transmit the again increased or decreased pressure through the
agency of a fluid to another plug, and so on "ad infinitum ;" or if it be the
last of the series, it may have an indicating column of such fluid as is most
suitable for the particular purpose of the gauge. Indicating columns may
also, if required, be attached to the first or any other of the series, as well as
to the last. I also employ a moveable plug or piston, of such a shape that
the pressure to be indicated is applied between two of its opposite parts or
surfaces, the difference in areas of such surfaces being in the same proportion
to that part of the same plug which acts upon the indicating fluid as it is
desired to lengthen or shorten the natural column above or below its natural
height (of this Fig. 3 in the accompanying Sheet of Drawings is an example).
To prevent the escape of the fluid whose pressure it is wished to indicate, as
also that of the fluid used for indicating, and to prevent the adhesion of the
plug or piston from moisture, &c., I stretch or extend across the ends or other
parts of the said moveable plug or piston a thin film of prepared india-rubber,
gutta percha, thinly laminated metal, or any other suitable metal or material,
or I use a light metallic or other packing for this purpose, or a capsule made
of metal, india-rubber, gutta percha, or other suitable material, such capsule
being made to press upon either or both the ends or other parts of the moveable
plug or piston, and of such a shape that the compression of its parts, which

page_text: may take place by the small motion of the said plug or piston, will not affect
the area which it may present to the fluid. A capsule of the form shewn in
section at Fig. 8, may be used, the pressure of the fluid being applied either
externally or internally. By preference I use a thin film of prepared india-
rubber, and to preserve it from deterioration, caused by its immediate contact
with metal, I cover such parts of the metal with a varnish or lacquer made
from shellac and spirits of wine or other suitable substances, or the metal in
such parts may be tinned. I use a glass tube for indicating the
bore of which I prefer to be of a small area (say about one-eighth of an inch
in diameter), the advantage obtained having a tube of a small bore being
that a very small motion is required to displace the indicating fluid necessary
for the filling of such glass tube.
pressure, the
The manner in which my said Invention is to be performed will be clearly
understood by reference to the accompanying Sheet of Drawings, with the
figures and letters of reference thereon.
Fig. 1 is an elevation of a pressure gauge suitable for steam or other fluid,
with a range to indicate to sixty pounds on the square inch, the principal parts
being shewn in section; Fig. 2 is an elevation, partly in section, of a gauge
for indicating the pressure below that of the atmosphere (or vacuum) as well
as the pressure above that of the atmosphere; Fig. 3 is an elevation in section
of a portion of a gauge, with a modification in the shape of the plug or piston;
Fig. 4 is an elevation, partly in section, of an anemometer or gauge for
registering the force or velocity of the wind; Fig. 5 is an elevation, princi-
pally in section, of a gauge suitable for indicating light pressures or weights;
by attaching a bent funnel or mouthpiece in place of the pipe or tube a, a,
this construction of gauge may also be used as an anemometer or air-pressure
gauge. Fig. 6 is an elevation of a gauge (partly in section) suitable for
registering heavy pressures, such as are used for hydraulic presses, &c., the
intervening space between the two plugs being filled with mercury or other
fluid, by means of which the pressure (reduced in the proportion of the areas of
the ends of the first plug) is transmitted to the small end of the second plug, and
by it to the mercury or other fluid used for indicating; Fig. 7 is an elevation of
gauge-suitable-for-indicating-weights_or_pressures, such weights being applied
upon the top end of the wrought iron or steel pin m, which is supported in a
vertical position by the framing n, n. In the following description the same
letters refer to similar parts in all the Figures.
In Fig. 1, a, a, is a tube or the lower end of a cock or tap, communicating
with the boiler or other vessel containing the fluid, the pressure of which is
to be indicated; a small ring or washer c, c, is screwed on to its end, against

page_text: which the nut b, b, which screws into the top part of the metal cylinder f, f,
presses, thereby by means of the packing d, d, making the joint tight; e, e, is
a small ring or nut fitted into the top part of the said cylinder f, f; 9, 9, is
also a small ring, which fits easily into a recess; h, h, is a moveable plug or
piston, made of metal or other suitable material, and fitted accurately at its
ends into the cylinder f. f. A thin film of prepared india-rubber, gutta percha,
or other suitable substance is stretched or placed across the ends of the
plug h, h, and is firmly held in its place at the top end by the small ring g, g,
being screwed down by the nut e, e, and at the bottom end by being screwed
between the flanges of the cylinder ff, and those of the bent or wrought-
iron vessel i, i, attached to the lower part of the cylinder f, f, as is shewn in
the section; j, j, represents the mercury or other indicating fluid; 1, l, is a
glass tube for indicating the pressure, such tube being attached to the bent
iron vessel i, i, by means of a small nut, and packing in the ordinary way; it
is surrounded in part by a brass tube containing a graduated scale. k is a
small hole drilled through the side of the cylinder f, f, for the purpose of
preventing any compression or attenuation of air within such cylinder, which
the motion of the piston would otherwise create.
In Fig. 2, h' is a small wrought-iron ring or washer, of the same area as
the top end of the plug h, h, which is attached to the top end of such plug
by means of a small set screw, as is shewn in the Drawing, a similar iron
ring or washer h², of the same area as the larger end of the plug h, h, is also
attached thereto by means of a small set screw. The prepared india-rubber or
other substance used to prevent breakage is fixed between the surfaces of
the ends of the plug and these rings or washers by means of the set screws
above referred to.
In Eig. 3 the top parts of the piston are represented as being made pressure
tight by means of small metallic rings or packings.
In Fig. 4, f, f, and f, f, are metal cylinders screwed together at their flanges
by small set screws; h and h, h, are plugs or pistons; i, i, is a wrought or
cast-iron vessel containing the mercury or other indicating fluid j, j, attached
to the lower cylinder f. f.; j is a fluid which fills the space between the plugs
h and h, h; 1, 1, is a glass tube with graduated scale, &c.; e, e, is a nut which
screws down the small ring or washer g, g; o, o, is a cranked lever moving
on a well fitted pin at r, the top part of this lever is made so as to be easily
detached, and so as to make the instrument more portable; upon the lever
o, o, is fitted a moveable socket m, which may be easily fixed to any part of the
lever o, o, by means of the set screw p; n, n, is the edge of a thin sheet of iron
vane, against which the wind impinges. This vane may be made so as to fold up

page_text: so as to present a greater or less surface to the wind; q is a small set screw,
the end of which presses upon the piston h, which transmits the pressure of
the wind received upon the vane n, n, and communicated to the lever o, o,
through the fluid j, on to the piston h, h, and which consequently transmits
such pressure increased in proportion as its area is greater than that of the
top plug
or piston h through its smaller end or surface on to the indicating
fluid j, k, is a small hole for vent; thin films of india-rubber or other
suitable substance are stretched across the surfaces of the plugs h and h, h.
The various parts of these gauges shewn in Figs. 5, 6, and 7, will be readily
understood from the foregoing description.
Having thus fully described the nature of my said Invention and the
manner in which the same is to be performed, I desire it to be distinctly
understood that I do not confine myself to the precise details herein set forth,
as such may be varied or modified without departing from the principle
thereof; but I claim as my Invention, and which to the best of my knowledge
and belief has not been hitherto used within the realm, the interposition of
one or more pistons or plugs with differential areas between the fluid or
weight desired to be indicated, and the fluid used for indicating, and the
application of the same to the purposes herein set forth, and to other purposes
for which the gauges may be suitable, as such improvements are herein
described and illustrated in the accompanying Sheet of Drawings.
In witness whereof, I, the said James Fogg, have hereunto set my
hand and seal, this Tenth day of February, in the year of our Lord
One thousand eight hundred and fifty-nine.
Signed, sealed, and delivered by the
within-named James Fogg, in the
presence of
E. J. HUGHES, Patent Agent,
Manchester.
JAMES FOGG. (L.S.)