IMPROVEMENTS IN GAUGES OR WAR Acana Dona
Year: 1868

page_text: LETTERS PATENT to Henry James Hogg King, John Auchinvole,
and Alexander Patrick, all of Glasgow, in the County of Lanark,
North Britain, for the Invention of "IMPROVEMENTS IN GAUGES OR
WAR
Acana Dona"
PROVISIONAL SPECIFICATION left by the said Henry James Hogg
King, John Auchinvole, and Alexander Patrick at the Office of
the Commissioners of Patents, with their Petition, on the 16th
May 1868.
We, HENRY JAMES HOGG KING, JOHN AUCHINVOLE, and ALEXANDER
PATRICK, all of Glasgow, in the County of Lanark, North Britain, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN
GAUGES OR APPARATUS FOR ASCERTAINING PRESSURE," to be as follows, that is
to say :-
This Invention relates to various modifications of gauges or apparatus
for ascertaining pressure, and has generally for its objects increased
accuracy and reliability.

page_text: In a modification designed for steam pressure, but also applicable
otherwise, there is a tube of glass or other suitable material, which is
bent so as to present a series of vertical lengths united alternately at
the top and bottom, and which contains mercury and a lighter liquid,
the latter being by preference a mixture of glycerine and water.
These liquids are disposed so that when there is no pressure acting in
the end of the tube communicating with the boiler the mercury occupies
the lower parts of the several lengths and the other liquid the upper
parts. When fluid pressure is allowed to act on the inner end of the
tube the mercury rises up the outer length of each pair, causing the
contents of the outer lengths to preponderate over those of the inner
lengths, and it is the sum of the several amounts of preponderance
that measures or corresponds to the pressure applied. The indication
may be read off by means of a scale or scales applied to one or more of
the lengths of tube. A tube of a flat form is preferred, which admits
of its being of small area and at the same time of the mercury being
clearly and distinctly visible. In some cases the part of the tube from
which the indications are read off is made of larger area than the other
parts so as to contract the length of the scale.
Another improvement consists in applying a float on the outermost
portion of mercury which will remain at the highest point attained by
the mercury, and so indicate the maximum pressure that may have been
reached during an interval. A similar float may be used for indicating
a minimum pressure.
The improved gauge is arranged in a casing or box with only the
indicating part and scale visible, but which may have a cover or door
to be generally locked, but which can be opened for inspecting the
entire tube, and for measuring the column of mercury in each length
so as at any time to check the accuracy of the gauge.
Barometers or apparatus for ascertaining atmospheric pressure may
be made with the herein-before described improvements, or a. barometer
may be made according to a modification in which a closed downward
bend is added to the top of the ordinary barometer tube, and is of
larger area than the bottom bend. The mercury is made to occupy
part of the upper bend in addition to filling the main length and partly
filling the bottom length, and in consequence of the differential areas
an increased length or range of scale is obtained as compared with
ordinary barometers.

page_text: to
Another modification of gauge comprised in the present Invention is
designed for ascertaining high hydraulic pressures, and so
eliminate the ordinarily troublesome element of friction, or in other
words to contain within itself the means for accurately correcting for
friction. A moving cylinder is provided for the pressure to act in and
works with cupped leathers on a fixed trunk or rod bored to fit a rod
or plunger fixed to the bottom of the moving cylinder. The bore of
the trunk can be put in communication with the atmosphere or with
the inside of the cylinder at pleasure by means of screw plugs or
otherwise. These arrangements admit of the pressure being taken on
two different areas with the same friction in both cases, and the
difference of the two pressures indicated will obviously be the true
pressure on the area of the central rod.
Another improvement in gauges for ascertaining high pressures is
applicable to such as are made with flexible, metallic, or other
diaphragms, and consists in combining two opposite connected
diaphragms of different areas, when the pressure acting between them
will cause a movement corresponding to the difference only of the
areas instead of to the entire area of either. In connection with the
mercurial gauges herein-before described it is further proposed to apply
glass tubes of varying thickness or to add suitably shaped glass with
or without an intermediate liquid in order to produce a magnified
appearance of the mercurial column,
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Henry James Hogg King, John Auchinvole, and
Alexander Patrick in the Great Seal Patent Office on the 14th
November 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, HENRY
JAMES HOGG KING, JOHN AUCHINVOLE, and ALEXANDER PATRICK, all
of Glasgow, in the County of Lanark, North Britain, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Sixteenth day of May, in the year of
our Lord One thousand eight hundred and sixty-eight, in the thirty-
fst year of Her reign, did for Herself, Her heirs and successors, give
and grant unto us, the said Henry James Hogg King, John Auchinvole,

page_text: and Alexander Patrick, Her special licence that we, the said Henry
James Hogg King, John Auchinvole, and Alexander Patrick, our
executors, administrators, and assigns, or such others as we, the said
Henry James Hogg King, John Auchinvole, and Alexander Patrick,
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
"IMPROVEMENTS IN GAUGES OR APPARATUS FOR ASCERTAINING PRESSURE," upon
the condition (amongst others) that we, the said Henry James Hogg
King, Jolin Auchinvole, and Alexander Patrick, our executors or
administrators, by an instrument in writing under our, 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 we, the said Henry James Hogg King, John
Auchinvole, and Alexander Patrick, 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 in writing, reference being had to the accompanying
Drawings, that is to say :-
Our said Invention relates to various modifications of gauges or
apparatus for ascertaining pressure, and has generally for its objects
increased accuracy and reliability, one important part of it comprising
various arrangements for enabling pressure gauges to be checked and
their accuracy tested at any time.
And in order that our said Invention and the manner of performing
the same may be properly understood we have hereunto appended two
Sheets of explanatory Drawings to be herein-after referred to and
representing various modifications of our improved apparatus.
A mercurial gauge designed for steam pressure, but also applicable
otherwise, is shown in Figures 1 and 2, the case door being shown open
in Figure 1 and shut in Figure 2. In this gauge there is a tube of
glass which is bent so as to present a series of vertical lengths 1 to 8
united alternately at the top and bottom, and which contains mercury,

page_text: show by a blue color, and a lighter liquid shown by a rose color.
The liquids are filled in so that when there is no pressure acting in
the end of the tube at 9 which communicates with the boiler the
mercury will occupy the lower parts of the several lengths and the other
liquid the upper parts, as shown in Figure 1. Then when pressure is
allowed to act in the inner end 9 of the tube the mercury will rise up
the outer lengths 2, 4, 6, 8, of each pair, causing the contents of such
outer leths to preponderate over those of the inner lengths 1, 3, 5, 7,
and it is the sum of the several amounts of preponderance that measures
or corresponds to the pressure applied.
There is no pressure gauge more reliable than the ordinary mercurial
gauge, but it is unsuitable for any but low pressures on account of the
great vertical length required. Our improved gauge is as reliable as
the ordinary, whilst the difficulty of length is overcome by arranging
a number of columns of mercury side by side in such a way as by the
summation of their several effects to answer the purpose of a single
long column. It is of importance that the lighter of the two liquids
should be one of sufficient stability and inalterability, and glycerine
either pure or mixed with a little water being possessed of these
properties is the liquid employed. This glycerine is filled in above the
mercury in the innermost tube length 1 (as well as in the other lengths),
and is continued up to an elastic diaphragm 10 of thin rubber which
is interposed to prevent deposits from the steam pipe from entering and
choking the fine bore of the gauge tube. Different modes of arranging
the diaphragm 10 are shown in Figures 1 and 2. In the former it is
shown as a sheet stretched across a cup or enlargement 11 formed with
a tube cemented to the end of the glass gauge tube 9, whilst in the latter
it is shown as a cylinder or tube 10 closed at its upper end but com-
municating at its bottom end with the gauge tube and with the steam
pressure acting on its outside in a larger tube in which it is enclosed and
which is in communication with the steam pipe.
Another arrangement for preventing deposits from the steam pipe
from entering the fine bore of the gauge tube is shown in section in
Figure 3. In it a small brass cylinder or vessel 11 is fixed to the end 9
of the gauge tube, and inside of it there is a small tube which projects
down from the steam cock 15 to within a short distance of the bottom,
whilst another tube communicating with the gauge tube reaches nearly
to the top. Water is put into the vessel and confines some air in the

page_text: upper part through which the pressure is transmitted, whilst deposits
are retained in the bottom of the vessel 11. The indication may be
read off from any of the tube lengths, and it is convenient to arrange a
scale 12, as shown in Figure 2, upon the door 13 of the case in which
the gauge is enclosed, one of the tube lengths being seen through a slot
in the door with the scale close beside it. The door or cover 13 should
in general be locked, but may be opened for inspecting the entire tube
and for measuring the columns of mercury in each length so at any
time to check the accuracy of the gauge.
We proposed to use a glass gauge tube of a flat form in order to admit 1
of the mercury being of small area and at the same time clearly
distinctly visible; we also proposed to apply glass tubes of varying
thickness or to add a glass casing with or without an intermediate liquid
in order to produce a magnified appearance of the mercurial column.
We however find that a plain round tube with a very small bore
compared with its thickness answers the purpose quite as well and in
a simpler manner. We employ a tube of about half an inch in diameter
with a bore of about a tenth of an inch.
We may here state that we proposed to adopt certain other minor
arrangements as described in the Provisional Specification lodged on
applying for the herein-before in part recited Letters Patent, but not
having found them to be of the utility we expected we do not make any
claim herein respecting them.
Whilst it is in some cases desirable to obtain a shorter scale for a
given range of pressures than that associated with the simplest form
of the instrument, it is on the contrary in other cases advantageous to
lengthen the scale, as for example in a barometer or gauge for ascertaining
atmospheric pressure.
An arrangement for effecting this is shown in Figure 4, and con-
stitutes the second modification of apparatus comprised in the Invention.
In this modification of barometer a closed downward bend z is added
to the top of the ordinary barometer tube and is of larger area than
the bottom bend y. The mercury is made to occupy part of the upper
bend in addition to filling the main length and partly filling the
bottom length y, and in consequence of the differential areas an increased
length or range of scale is obtained as compared with ordinary

page_text: barometers. As the mercury in the upper bend is apt to separate
another bend to is added and is partly filled with glycerine.
The third modification of apparatus comprised in our Invention is
designed for ascertaining high hydraulic pressures and so as to eliminate
the ordinarily troublesome element of friction; or in other words to
contain within itself the means for accurately correcting for friction.
This modification is shown in vertical section in Figure 5, and in face
view, but with parts broken away, in Figure 6. It forms a very con-
venient and reliable standard pressure gauge for testing other gauges
and for marking their scales by. The liquid or fluid the pressure of
which is to be measured is admitted by a cock 15 into a cylinder 16
from which there projects downwards a ram 17 working through a
cupped packing leather. The ram is bored accurately to move on an
accurately turned plunger or rod 18 fixed in the top of the cylinder 16,
and a small outlet closed by a screw plug 19 is provided in the bottom
of the hollow ram 17. When the plug 19 is closed the internal pressure
takes effect on the entire area of the ram 17 (as the plunger 18 does not
fit it with perfect tightness), but when the plug is opened the arca acted
upon is diminished to the extent of that of the plunger 18, as the interior
of the ram 17 is then open to the atmosphere. The pressure can then
be taken on two different areas with the same friction in both cases,
and the difference of the two pressures indicated will obviously be the
true pressure on the area of the central plunger 18.
The pressure
applied to the ram 17 is communicated thereby to a pillar 20 which
is held up by a cylindrically coiled steel spring 21, the upper end of
which is fixed to the framing of the apparatus. The spring is arranged
to be strained or extended in a downward direction for the convenience
of originally measuring the extension produced by different pressures
by suspending actual weights directly from it, and of at any time testing
its accuracy by again applying such weights, for which purpose the
pillar 20 is formed with an eye 22 at the bottom for hooking on the
weights. An index or pointer 23 turning on a short horizontal spindle
serves for indicating the pressures on a suitable circular scale, and is
moved by means of an arm 23 carrying an adjustable pin which rests on
a collar 24 adjustable on the pillar 20.
The method of providing for the checking of a pressure gauge by arrang-
ing the parts so as to get indications of the pressure on different areas is
applicable to pressure gauges of various kinds, and a few examples of

page_text: such application are shown in Figures 7 to 12, representing respectively
the fourth, fifth, and sixth. modifications of apparatus comprised in our
Invention.
The gauge shown in vertical section in Figure 7 is of the kind in
which the pressure is indicated in connection with its action in extending
a metallic vessel 25 formed with sides of an undulated longitudinal
section. The plunger 18 is fixed to the top of the vessel 25, and works
in a bore 17 made for it in the body, whilst a screw plug 19 serves for
making a communication between the bore 17 and the atmosphere when
required.
The gauge shown in Figure 8 is of the kind in which the pressure
acts on a diaphragm 26 of a flat contour, but corrugated in concentric
circles. A second smaller diaphragm 27 is added, being connected to
the larger one 26 by a spindle 28. Under the smaller diaphragm there
is a cavity 17 which can be put in communication with the atmosphere
by a plug 19 when required, whilst it communicates with the steam
pipe by an extremely small aperture. When the cavity 17 is open to
the atmosphere the gauge becomes a very good one for high pressures,
because whilst the effective pressure corresponds to only the difference
between the areas of the two diaphragms the elasticity of the entire
diaphragms is called into play. A second screw plug may be introduced
if wished for closing the aperture by which the steam pipe communi-
cates with the smaller cavity 17.
The fifth modification of gauge is shown in external elevation in
Figure 10, on Sheet 2 of the Drawings, in section in Figure 11, and
in partial section in Figure 12. In this improved gauge the pressure
acts inside of a tube 29 of vulcanised rubber, the bottom of which is
fixed to the body of the instrument, whilst the top is fixed to a movable
head 30 which has fixed to it a rod or plunger 18 working in a bore 17
made for it in the body. The elastic tube 29 is encompassed by a
cylindrically coiled steel spring 21 fixed to the head 30 at the top and
to the body at the bottom, and this spring both resists the longitudinal
extension of the tube 29, and protects the tube from undue lateral
expansion. The cock 15 is arranged in connection with passages in
the body of the instrument in such a way that the bore 17 may be
put in communication with the atmosphere or with the internal pressure
as required, as will be easily understood from the Figures. The vertical
movement of the head 30 is communicated to an index 31 which sweeps

page_text: over two scales, one, 32, for ordinary use, and the other, 33, for use
when the bore 17 is in communication with the atmosphere.
Having thus particularly described our said Invention, and the manner
in which the same is to be performed, we have to state that we do not
restrict ourselves to the precise details herein described or delineated,
but that what we believe to be novel and original, and claim as the
Invention secured to us by the herein-before in part recited Letters
Patent is,
-
1. The making of a pressure gauge with a number of mercurial
columns separated by glycerine or similar liquid, and with appliances
for preventing the entry of deposits into the tube, substantially as
herein-before described.
2. The making of a mercurial barometer with an enlarged scale by
arranging the mercury to rise in one branch of the tube as it falls in
another of different area, substantially as herein-before described.
3. The making of a pressure gauge so that a part of the area
respecting which the pressure is indicated may be put into communi-
cation with the pressing fluid or with the atmosphere, whereby the
indication may be checked and the effects of friction be corrected for,
substantially as herein-before described.
4. The general construction and modes of combining the parts of the
various modifications of gauges herein-before described.
In witness whereof, I, the said Alexander Patrick, on behalf
of the said Henry James Hogg King, John Auchinvole, and
myself, have hereunto set my hand and seal, this Thirteenth
day of November, in the year of our Lord One thousand eight
hundred and sixty-eight.
Witness,
EDMUND HUNT,
Patent Agent,
Glasgow.
ALEXR. PATRICK. (L.S.)