AN IMPROVED INSTRUMENT FOR MEASURING, INDICATING, AND RECORDING, VARIATIONS OF PRESSURE WHETHER HIGHER OR LOWER THAN THAT OF THE ATMOSPHERE FOR USE IN REGULATING THE VENTILATION OF MINES AND FOR OTHER PURPOSES
Year: 1882

page_text: ETTERS PATENT to Alexander Melville Clark of the firm of A. M and
W. Clark of 53, Chancery Lane, in the County of Middlesex, Patent Agents
for an Invention of AN IMPROVED INSTRUMENT FOR MEASURING, INDICATING,
AND RECORDING, VARIATIONS OF PRESSURE WHETHER HIGHER OR LOWER
THAN THAT OF THE ATMOSPHERE FOR USE IN REGULATING THE VENTILATION
OF MINES AND FOR OTHER PURPOSES Communicated to him from abroad by
Eugène Bourdon of Paris, France
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark
at the Office of the Commissioners of Patents on the 13th June 1882.
ALEXANDER MELVILLE CLARK of the firm of A. M. & W. Clark of 53
Chancery Lane in the County of Middlesex, Patent Agents, "AN IMPROVED
INSTRUMENT FOR MEASURING, INDICATING AND RECORDING VARIATIONS OF
PRESSURE, WHETHER HIGHER OR LOWER THAN THAT OF THE ATMOSPHERE, FOR
USE IN REGULATING THE VENTILATION OF MINES AND FOR OTHER PURPOSES
[Communicated to him from abroad by Eugène Bourdon of Paris, France]
"
This Invention relates to an instrument for measuring and graphically recording
the degrees of pressure (whether higher or lower than that of the atmosphere)
produced either by the action of currents of air circulating in the atmosphere, or
by the action of ventilating apparatus such as employed in mines and in certain
industrial operations, the instrument, particularly when employed in nines, being
capable of giving an audible signal to denote when the ventilation of any part of
a mine is sufficient. The instrument may also be employed in connection with
anemometers used for meteorological observations and in all industrial and scientific
operations where it is desired to measure and record pressures above or below that
of the atmosphere, the instrument serving to indicate by a signal when the action
of the apparatus to which it is applied should be accelerated or retarded.

page_text: Under certain circumstances and notably in measuring the velocity of the wind
in the galleries of nines, it is important to use a manometer with closed ends in
order to meet the special requirements ofthe case.
The balance manometer of this Invention is designed to supply this
desideratum.
In order that the Invention may be more readily understood, I have illustrated
one example of the instrument in the accompanying Drawings wherein Figure 1 is
a side elevation, and Figure 2 a plan of the instrument It consists of two glass or
metal vessels E of cylindrical or other form hung on centres in the respectivo
forked ends of an equal arm balance beam A which is mounted to oscillate freely
on knife edges in a bracket B carried by a post or support N rising from a base O.
The beam instead of having arms of equal length, may be on the principle of the
steelyard, the relative lengths of the two arms being in any required ratio. Each
vessel E has nipples at the ends for the attachment of indiarubber tubes F H Has
hereafter described and with a scale E' whereon the level of the contained liquid
may be read off The vessels are put in free communication at bottom by a small
and very flexible tube F so that on introducing liquid (water, glycerine, mercury, &c.)
equilibrium will be established. To the upper end of each vessel is connected an
indiarubber tube H, the other ends of these tubes being open and led towards the
centre of the instrument where they are provided with connections I I. A rigid
arm C is attached to the beam beneath its centre of oscillation and carries a bob or
weight a secured by a set screw vand adjustable along rod C nearer to or farther
from the centre of oscillation, according to the degree of sensibility desired.
Another but flexible arm D fixed to the beam near its centre of oscillation, carries
a stylus p (a pen, pencil &c.) at its extremity which moves over a paper disc carried
on a plate K and marks thereon the curve denoting the variations of pressure it is
required to register. The disc K receives a chronometric circular motion from a
clock movement J mounted on standard N at the rear of the beam
The plate
und disc of paper may in certain cases be replaced by a band of paper wrapped on
a cylinder.
The operation of the instrument when applied to register the variations of
pressure in the ventilation of mine galleries is as follows
A Lourdon's multiplying anemometer having been installed in the mine it is put
in communication with the manometer of this Invention by means of small tubes
the one commencing at the last tube of the anemometer and attached to the
connection 1 of the manometer the other presenting its orifice to the centre of the
flared or divergent side of the external tube of the anemometer, and attached to
the other connection I',
The air put in motion by the ventilating apparatus, or by the effect of the air
shafts produces in traversing the anemometer a variation of pressure proportional
to the velocity of the current. This variation is transmitted by tube H to that
one of the vessels of the manometer with which it communicates, and in virtue of
this difference of pressure a portion of the liquid passes from the one vase into
the other thereby causing the beam to be inclined until the weight of the liquid
displaced balances the effect of the variation of pressure produced by the aeriform
current whose velocity it is desired to ascertain the stylus which moves with the
beam tracing on the paper a curve representing the variations produced in the
working of the ventilating apparatus of the mine.
The instrument having been first adjusted by means of a fan or other method,
the velocities corresponding to the sinuosities of the curves may be ascertained by
simply reading off the numbers upou a suitably divided scale applied to the paper
disc. The clockwork mechanism being regulated to rotate the paper disc once in
twenty-four hours and the surface of the disc being divided by twenty-four
equi distant radii the variations of velocity of the wind will be graphically
recorded and the hours at which they occur indicated.
In order to indicate when the ventilation of a mine is insuflicient or too active,
I utilise the movement of the beam to establish electrical connection or release

page_text: suitable alarm apparatus according to the necessities of the case and placed in
proximity to the engineers in charge of the ventilating apparatus or furnace.
LL are small glass cups containing mercury and furnished at their underside with
copper terminals to hold wires which connect with electric bells or other alarms.
These cups are fixed adjustably on the standard N to enable their position to be
varied. M M are two pairs of bent copper wires fixed on the beam, one pair at
each side of its axis, the wires of each pair being insulated from one another.
When by the inclination of the beam to one side or the other, one pair dips into
the mercury, an electric circuit is closed and the corresponding alarm sounded.
The alarms of the two circuits are different in pitch, the one serving to indicate
that the ventilation is insufficient, the other that it is too active and requires
moderating, while the silence of both will indicate that the ventilation is in the
normal condition

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Alexander Melville Clark in the Great Seal Patent Office
on the 13th December 1882
"
ALEXANDER MELVILLE CLARK of the Firm of A. M. and W. Clark of 53
Chancery Lane in the County of Middlesex Patent Agents AN IMPROVED
INSTRUMENT FOR MEASURING, INDICATING, AND RECORDING VARIATIONS OF
PRESSURE, WHETHER HIGHER OR LOWER THAN THAT OF THE ATMOSPHERE, FOR
USE IN REGULATING THE VENTILATION OF MINES AND FOR OTHER PURPOSES
A communication to me from abroad by Eugéne Bourdon of Paris, France
21
This Invention relates to an instrument for measuring and graphically recording
the degrees of pressure (whether higher or lower than that of the atmosphere)
produced either by the action of currents of air circulating in the atmosphere, or
by the action of ventilating apparatus such as employed in mines, and in certain
industrial operations, the instrument, particularly when employed in mines, being
capable of giving an audible signal to denote when the ventilation of any part of a
mine is insufficient. The instrument may also be employed in connection with
anemometers used for meteorological observations and in all industrial and scientific
operations where it is desired to measure and record pressures above or below that
of the atmosphere, the instrument serving to indicate by a signal when the action
of the apparatus to which it is applied should be accelerated or retarded Under
certain circumstances and notably in measuring the velocity of the wind in the
galleries of mines, it is important to use a manometer with closed ends in order to
meet the special requirements of the case The balance manometer of this Invention
is designed to supply this desideratum.
In order that the Invention may be more readily understood I have illustrated
one example of the instrument in the accompanying Drawings, wherein Figure 1 is
a side elevation, and Figure 2 a plan of the instrument. It consists of two glass
or metal vessels E of cylindrical or other form hung on centres in the respective
forked ends of an equal arm balance beam A which is mounted to oscillate freely
on knife edges in a bracket B carried by a post or support N rising from a base O.
The beam instead of having arms of equal length may be on the principle of the
steelyard, the relative lengths of the two arms being in any required ratio. Each
vessel E has nipples at the ends for the attachment of indiarubber tubes F H H as
hereafter described and is provided with a scale E¹ whereon the level of the
contained liquid may be read off The vessels are put in free communication at
bottom by a small and very flexible tube F resting on a block G whereby on
introducing liquid (water, glycerine, mercury, &c.) equilibrium will be established.
To the upper end of each vessel is connected an indiarubber tube H, the other ends
of these tubes H H being open and led towards the centre of the instrument where
they are provided with connections I I¹. A rigid arın C is attached to the beam at
right angles and beneath its centre of oscillation and carries a bob or weight a
secured by a set screw and adjustable along rod C nearer to or farther from the
centre of oscillation, according to the degree of sensibility desired. Another but
flexible arm D fixed to the beam near its centre of oscillation carries a stylus 2
(a pen, pencil, &c.) at its extremity which moves over a paper disc carried on a
plate K and marks thereon the curve denoting the variations of pressure it is
required to register The disc K receives a chronometric circular motion from a
clock movement J mounted on standard N at the rear of the beam. The plate and

page_text: disc of paper may in certain cases be replaced by a band of paper wrapped on a
cylinder.
The operation of the instrument when applied to register the variations of
pressure in the ventilation of mine galleries, is as follows:-
A Bourdon's multiplying anemometer having been installed in the mine, it is
put in communication with the manometer of this Invention by means of small
tubes, the one commencing at the last tube of the anemometer and attached to the
connection I of the manometer, the other presenting its orifice to the centre of the
flared or divergent side of the external tube of the anemometer and attached to the
other connection I The air put in motion by the ventilating apparatus or by the
effect of the air shafts, produces in traversing the anemometer a variation of pressure
proportional to the velocity of the current. This variation is transmitted by
tube H to that one of the vessels of the manometer with which it communicates,
and in virtue of this difference of pressure, a portion of the liquid passes from the
one vase into the other, thereby causing the beam to be inclined until the weight of
the liquid displaced balances the effect of the variation of pressure produced by the
acriform current whose velocity it is desired to ascertain, the stylus which moves
with the beam tracing on the paper a curve representing the variations produced
in the working of the ventilating apparatus of the mine
The instrument having been first adjusted by means of a fan or other method,
the velocities corresponding to the sinuosities of the curves may be ascertained by
simply reading off the numbers upon a suitably divided scale applied to the paper
disc. The clockwork nechanism being regulated to rotate the paper disc once in
24 hours and the surface of the disc being divided by 24 equi-distant radii, the
variations of velocity of the wind will be graphically recorded and the hours at
which they occur indicated.
In order to indicate when the ventilation of a mine is insufficient or too active,
I utilise the movement of the beam to establish electrical connection or release
suitable alarm apparatus (according to the necessities of the case) placed in
proximity to the engineers in charge of the ventilating apparatus or furnace.
LL are small glass cups containing mercury and furnished at their underside with
copper terminals to hold wires which connect with electric bells or other alarms.
These cups are fixed adjustably on the standard N to enable their position to be
varied. M M are two pairs of bent copper wires fixed on the beam, one pair at
each side of its axis, the wires of each pair being insulated from one another.
When by the inclination of the bean to one side or the other, one pair dips into
the mercury, an electric circuit is closed and the corresponding alarm sounded.
The alarms of the two circuits are different in pitch, the one serving to indicate
that the ventilation is insufficient, the other that it is too active and requires
moderating, while the silence of both will indicate that the ventilation is in the
normal condition.
Having described the nature of the said Invention and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
hereinbefore in part recited Letters Patent is
1st In an instrument for measuring, indicating, and recording variations of
pressure above or below that of the atmosphere, the combination of two vessels
placed in communication with one another by their lower extremities and suspended
respectively at the respective ends of a balance beam mounted to oscillate freely,
substantially as herein shown and described.
2nd In an instrument such as herein described, the combination with the
beam A of the arm C and adjustable bob a, substantially as and for the purpose
specified.
3rd In an instrument such as herein described, the combination of the beam A,
the communicating vessels E suspended therefrom, the adjustably weighted arm
and the rod D carrying a suitable marker substantially as and for the purpose
specified.

page_text: 4th In an instrument such as herein described, the combination of the communi-
cating vessels E suspended from a balance beam provided with the adjustably
weighted arm and a marker p, and of the disc and its actuating clockwork j,
substantially as and for the purpose specified.
5th In an instrument such as herein described, the combination of the flexible
tubes H provided with connections I l' with the respective vessels E suspended
and placed in communication as described.
6th In an instrument such as herein described, the combination with the balance
beam and its actuating apparatus of the pairs of electrical connections L and M
combined for operation substantially as and for the purpose specified.
In witness whereof I the said Alexander Melville Clark have hereunto set my
hand and seal this thirteenth day of December, A.D. 1882.