IMPROVED APPARATUS FOR TESTING AND INDICATING THE PRESENCE AND PERCENTAGE ⚫ OF COMBUSTIBLE GASES IN AIR, SUCH APPARATUS BEING ESPECIALLY APPLICABLE TO THE DETECTION OF FIRE- DAMP IN COAL MINES
Year: 1881

page_text: LETTERS -PATENT to Arthur William Lovell Reddie, of the Office for Patents,
-
66, Chancery Lane, in the County of Middlesex, Patent Agent, for an
Invention of "IMPROVED APPARATUS FOR TESTING AND INDICATING THE
PRESENCE AND PERCENTAGE ⚫ OF COMBUSTIBLE GASES IN AIR, SUCH
APPARATUS BEING ESPECIALLY APPLICABLE TO THE DETECTION OF FIRE-
DAMP IN COAL MINES." A communication from abroad by Denis Monnier,
of Paris, in the Republic of France.
PROVISIONAL SPECIFICATION left by the said Arthur William Lovell
Reddie at the Office of the Commissioners of Patents on the 24th January
1881.
ARTHUR WILLIAM LOVELL REDDIE, of the Office for Patents, 66, Chancery
Lane, in the County of Middlesex, Patent Agent. "IMPROVED APPARATUS FOR
TESTING AND INDICATING THE PRESENCE AND PERCENTAGE OF COMBUSTIBLE
GASES IN AIR, SUCH APPARATUS BEING ESPECIALLY APPLICABLE TO THE
DETECTION OF FIRE-DAMP IN COAL MINES." [A communication from abroad by
Denis Monnier, of Paris, in the Republic of France.]
The object of this Invention is to detect the presence and proportion of con-
bustible gas in air, and especially the marsh gas or fire damp in coal mines, and
to automatically transmit an indication thereof to a receiver placed in any
convenient position.
For this purpose an apparatus has been devised, consisting of three main
features, viz., a test apparatus wherein the mixture of gas and air is exploded and
caused to act upon a manometer, a transmitting apparatus for conveying an exact
indication of the change produced on the manometer, and a receiving apparatus for
indicating the same and conveying an alarm if necessary.
This apparatus is based on a well known re-action. "Methan" or marsh gas in the
presence of an excess of atmospheric air decompose when subjected to certain

page_text: 2nd. A transmitter.
3rdly. A receiver.
The various parts of the analyser or test apparatus are mounted on one side of
a brass plate, and consists of a combustion chamber, its manometer, and an arrange-
ment of clockwork. On the other side are the transmitter and an apparatus for
locking and releasing certain tubes, the whole being encased in a well closed box.
The combustion chamber is a small glass receptacle, through the longer axis of
which passes a slender platinum wire. It communicates with a glass manometer
containing mercury, and it carries moreover laterally and towards its extremities
two nozzles on which are fixed india rubber tubes. One of these tubes passes
first beneath a locking lever, and thence leads to a pair of bellows which are
operated by clock work. The other tube, which is intended to receive the air of
the mine, issues by an opening made in one of the sides of the box which encloses
the apparatus.
The contacts are distributed by a disc and pointer also operated by clockwork.
On the other side of the brass plate are situate, 1st, the apparatus for locking
and releasing the india rubber tubes.
This consists of an electro magnet, wound with a thick wire, and of a soft iron
armature in the form of an inverted T (1), the horizontal branch of the 1 being
supported by two screws. When the current passes into the electro-magnet
this piece rocks and carries with it a lever which presses upon the india rubber
tubes which rest against a metallic backing plate. This backing plate is not fixed
but it is arranged in such a manner as to maintain the parallelism of the stroke
of the blade with the backing plate. Thus the india rubber tubes are hermetically
closed.
The end of this lever is bevilled and rests against a cone of steel fixed on the
rocking armature of a second electro magnet intended to release the tubes. This
cone is kept down by a spring which also ensures the separation of the armature
from the second electro magnet.
The tubes of india rubber placed beneath the lever blade serve as springs and
tend to push the said blade away. In this position the bevilled end of the lever
blade is brought towards the apex of the cone, but when the current passes into
the first electro magnet the lever blade being attracted lifts the cone, passes
slightly beyond its base, and is arrested by the coiled spring. The rubber tubes
remain closed up to the moment when one of the clockwork contacts completes
the circuit of the second electro magnet destined to release them.
Before describing the transmitter it may be well to explain the principle of the
method which is employed.
Numerous tests have proved that the manometrical indications give results
which entirely agree when they are obtained under similar conditions, i.e., when
an exact record kept of the time during which the platinum wire is maintained
at a bright red heat, of the temperature of the surrounding air, and of the baro-
metrical pressure. It has thus been proved that the barometrical pressure exercises
relatively little influence on the results, the temperature affects them more, but
within limits wide enough to allow of the apparatus being adjusted before use
in the galleries of mines where the temperature is not subject to great variations.
Supposing that the analyser or test apparatus is required to be used in a gallery
of a mine where the temperature varies from 30° to 40° centigrade, it is regulated
in that case for a mean temperature of 35° centigrade.

page_text: To do this the combustion chamber and its manometer are placed in a stove at
a temperature of 35° centigrade, and the height of a column of mercury which will
indicate, a mixture of 5 volumes of "méthan" (or fire damp), and 95 volumes of
air is determined. This height, divided by 5, will give the height corresponding
to 1 per cent. of "methan." The experiment is repeated with 2, 4, 6, 8 per cent.
of gas to check the first result, and the height corresponding to 1 per cent. is thus
exactly fixed.
Let it be assumed that this height is 8mm. starting from 0° on the index of the
manometer, and from 0° at intervals of 8mm. the tube is pierced by a wire of
platinum heated to redness, and in these holes 9 wires of platinum, which penetrate
to the interior of the column of the manometer, are inserted and hermetically
secured. The manometer thus prepared is ready for action with its attendant
combustion chamber. Each such chamber should be carefully gauged and corrected,
as it is impossible to produce with the simple blow pipe chambers of exactly the
same capacity.
The above details will suffice to explain the operation of the transmitting
apparatus, which may be now described.
The contacts are given by means of a series of platinum wires fixed in the frame
of the manometer, and piercing it as above described. The mercury in permanent
contact with the negative pole of a battery through a wire will, as it rises, close
the circuit successively with each of these platinum wires, which are in turn
connected with metallic plates disposed radially upon an ebonite disc, which is free
sto rotate on its axis.
'
Directly the mercury touches the first wire of the scale the current passes
through the corresponding plate and the spring arm of an electro magnet, which,
by attracting its armature and bell crank lever, causes the ratchet wheel to
advance one tooth, and with it the ebonite disc. At the same moment a tail
piece of the bell crank lever comes in contact with a blade, and directs the current
of electricity in another direction.
The ebonite disc during the movement of rotation which it has just undergone
has displaced the first plate, and another plate has come to take its place beneath
the spring arm connected with, the electro magnet. The circuit but recently
completed by the first wire of the scale is thus broken, and will not be again
completed till the mercury in the manometer has reached the level of the second
wire, and so on.
It should be remarked that the mercury may fluctuate, even descend below the
level of the first wire, and anon regain that level, but it will not be able to
complete a circuit with that wire during the whole of the remainder of the
operation.
;
1:
The same motion is repeated each time the mercury reaches a new wire up to
the time when the movement of the clockwork, contact distributor, effects the
liberation from compression of the rubber tubes by means of a current which is
made to pass into an electro magnet, which, acting upon its armature, will lift
certain pawls. The ebonite disc thus set free and rotated by a weight will then
return to its normal position in which it is arrested by a stop.
At the same time the circuit is broken for a moment lest the mercury after its
fall and before it has regained its normal level should come again into contact with
the first or second wires of the scale by any rapid fluctuations.
As a modification of the arrangement which has been just described, the plates
may be fixed and disposed in a circle, and similarly mounted in ebonite, whereas
the spring may be carried by the disc and ratchet wheel. The first platinum wire
of the manometer is in communication, as before, with the first plate, the second
wire with the second plate, and so on. The manometer is arranged in such a
manner that the mercury cannot be forced out in case of the mixture on being
tested proving explosive.
The action of the apparatus is as follows:-The bellows act once every quarter
of an hour, and draw in the air of the mine by one of the tubes by six inspirations

page_text: and six expirations. This operation is amply sufficient to completely change the
air of the small combustion chamber.
About one minute afterwards a knife edge stop, placed on the circumference of a
disc operated by clockwork, strikes against the tail of a platinum lever, and causes
it to describe an arc over a circle of ivory, on which are mounted three platinum
contact plates. The first contact of short duration closes the circuit of an electro
magnet, and locks the tubes of rubber; the second contact, which lasts 15", conducts
the current into the platinum wire of the combustion chamber, and heats the wire
to redness. The pointer then takes a minute to reach the 3rd contact plate, which
is also connected with the combustion chamber, and heats the platinum a second
time to redness for another 15".
The knife edged stop on the circumference of the disc releases the pointer,
which drawn by the spring strikes against a stop, and reverts to its normal
position..
The knife edged stop then takes 10 minutes to reach a second ivory quadrant,
and it is during this time that the transmitter operates. The second ivory quadrant
is provided with 2 platinum contact plates. The first of these closes the circuit of
an electro magnet, and releases the tubes of rubber. Instead of breaking the
circuit, as above explained, it is preferable to utilize the movement of the armature
of this electro magnet to break contact until the mercury of the manometer has
regained its normal level..
The second contact directs the current into an electro magnet, and brings back
the spring arm to the left hand side of the first plate on the ebonite disc.
The receiver of the apparatus is almost identical with the transmitter above
described.
The plates are numbered consecutively, and indicate a progressive percentage of
fire damp.
By doubling the number of plates, or by quadrupling them, as well as the
platinum wires of the manometer, as high a percentage as 25 or 50, if desired, may
be indicated.
The numbered plates of the receiver are provided with contact points, in order
to sound a continuous alarum whenever the proportions of the gaseous mixture
approach the limit which it is undesirable to exceed.
This receiver may be placed in a central office, in the engine room, for instance,
and thence warnings may be issued in as many directions as desirable.
Each time that the mercury of the manometer in the analysing apparatus attains
a division the needle of the dial of the receiver will give a corresponding indica-
tion. The fluctuations which the mercury may experience will however not be
recorded, since each platinum wire can only transmit the current a single time.
The return to 0° of the receiving apparatus after each test is effected automatically
by clockwork.
The complete apparatus requires two Leclanché batteries (or other batteries
serving the same purpose), one for the test apparatus, the other for the receiver.
This second battery will be placed outside the mine.
If desired arrangements may be made to keep in action 4 of these apparatus in
different galleries of a mine by the aid of a single connecting line.
It will suffice for this purpose to set the clocks of the four test apparatus each 15
minutes fast of the other.
The regulating clock of the central receiver will effect the return to zero every
quarter of an hour.
For 5 apparatus the return to zero would require to be effected every 12 minutes.
Five is the maximum number of test apparatus which could be established by the
aid of a single wire.
The setting of the clocks of the test apparatus, when several are employed, may
conveniently be effected every morning by any well known means.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Arthur William Lovell Reddie in the Great Seal Patent Office
on the 22nd July 1881.
ARTHUR WILLIAM LOVELL REDDIE, of the Office for Patents, 66, Chancery
Lane, in the County of Middlesex, Patent Agent. "IMPROVED APPARATUS FOR
TESTING AND INDICATING THE PRESENCE AND PERCENTAGE OF COMBUSTIBLE
GASES IN AIR, SUCH APPARATUS BEING ESPECIALLY APPLICABLE ΤΟ THE
DETECTION OF FIRE-DAMP IN COAL MINES." A communication from abroad by
Denis Monnier, of Paris, in the Republic of France.
The object of this Invention is to detect the presence and proportion of
combustible gas in air, and especially the marsh gas or fire-damp in coal mines,
and to automatically transmit an indication thereof to a receiver placed in any
convenient position.
For this purpose an apparatus has been devised, consisting of three main
features, viz., 1, a testing apparatus wherein the mixture of gas and air is exploded
or decomposed and caused to act upon a nianometer; 2, a transmitting apparatus
for conveying an exact indication of the effect produced on the manometer; and, 3,
a receiving apparatus for indicating the same, and, if necessary, conveying an
alarm.
or
The action of the apparatus is based on a well known reaction. "Méthan "
marsh gas, in the presence of an excess of atmospheric air, decomposes when
subjected to certain influences, such as the spark from an induction coil, a platinum
wire heated to redness, and in divers compounds, such as napthaline, and carbonic
acid, and water.
Condensation results, and is caused to act directly upon a mercurial or metallic.
manometer of any convenient form, or else on membranes, either vegetable or
animal, which have been rendered impermeable.
The automatic "méthanometer" is composed of three parts, as already stated.
The testing apparatus is represented at Fig. 2 of the accompanying Drawing in full
size, with the exception of the clockwork movement shewn in the upper right-hand
corner, which is drawn half size.
The various parts of this apparatus are mounted on a strong brass plate, on one
side of which are situate the combustion chamber, the manometer, and arrangement
of clockwork, on the other side are the transmitter and an apparatus for locking
and releasing certain flexible tubes, the whole being encased in a well closed box.
The combustion chamber A (Fig. 2) is a small glass receptacle, through the
longer axis of which passes a slender platinum wire.
It communicates with a glass manometer D, Fig. 2, containing mercury, and it
carries, moreover, laterally, and towards its extremities, two nozzles on which are
fixed india rubber tubes a, a¹. One of these tubes a passes first beneath the locking
lever E, and thence leads to a pair of bellows which are operated by clockwork. The
other tube a¹, which is intended to receive the air of the mine, issues by an opening
made in one of the sides of the box which encloses the apparatus. The contacts
are distributed by a disc and pointer Z, also operated by clockwork.
The apparatus for locking and releasing the india rubber tubes consists of an
electro magnet Y wound with a thick wire, and of a soft iron armature in the
form of an inverted T (1) the horizontal branch of the 1 being supported by two
screws. When the current passes into the electro-magnet Y, this piece rocks and
carries down with it a lever E, which presses upon the india rubber tubes which
rest against a metallic backing plate N. This backing plate is not fixed, but is

page_text: arranged in such a manner as to maintain the parallelism of the stroke of the
blade with the backing plate. Thus the india rubber tubes are hermetically
closed.
The end of this lever E is bevilled, and rests against a cone of steel fixed on the
rocking armature x of a second electro-magnet X intended to release the tubes.
This cone is kept down by a spring f, which also ensures the separation of the
armature x from the second electro magnet X.
The tubes of india rubber placed beneath the lever blade E serve as springs, and
tend to push the said blade away. In this position the bevilled end of the lever
blade is brought towards the apex of the cone, but when the current passes into
the first electro magnet, the lever blade being attracted forces the cone upwards
and becomes locked on the other side of the base of the cone which is drawn down
by the coiled spring f. The rubber tubes remain closed up to the moment when
one of the clockwork contacts completes the circuit of the second electro-magnet X
destined to release them.
Numerous tests have proved that the manometrical indications give results which
entirely agree when they are obtained under similar conditions, i.e., when an exact
record is kept of the time during which the platinum wire is maintained at a
bright red heat, of the temperature of the surrounding air, and of the barometrical
pressure. It has thus been proved that the barometrical pressure exercises
relatively little influence on the results, the temperature affects them more, but
within limits wide enough to allow of the apparatus being adjusted before use in
the galleries of mines where the temperature is not subject to great variations.
Supposing that the testing apparatus is required to be used in a gallery of a mine
where, the temperature varies from 30° to 40° centigrade, it is regulated in that case
for a mean temperature of 35° centigrade.
To do this the combustion chamber and its manometer are placed in a stove at a
temperature of 35° centigrade (and the height of a column of mercury which will
indicate a mixture of 5 volumes of "méthan" (or fire-damp) and 95 volumes of air
is determined. This height, divided by 5, will give the height corresponding to
1 per cent. of "méthan." The experiment is repeated with 2, 4, 6 & 8 per cent. of
gas to check the first result, and the height corresponding to one per cent. is thus
exactly fixed. Let it be assumed that this height is 8mm. starting from 0° on the
index of the manometer, and from 0° at intervals of 8mm. the tube is pierced by a
wire of platinum heated to redness, and in these holes 9 wires of platinum, which
penetrate to the interior of the column of the manometer, are inserted and
hermetically secured. The manometer thus prepared is ready for action with its
attendant combustion chamber. Each such chamber should be carefully gauged
and corrected, as it is impossible to produce with the simple blow pipe chambers of
exactly the same capacity.
The above details will suffice to explain the operation of the transmitting
apparatus which is shewn in Fig. 1 as connected with the manometer.
The contacts are given by means of a series of platinum wires a, b, c, d, fixed in
the tube of the manometer and piercing it as above described. The mercury in
permanent contact with the negative pole of a battery through a wire x will, as it
rises, close the circuit successively with each of these platinum wires, which are in
turn connected with metallic plates a¹, b¹, c, d, disposed radially upon an ebonite
disc A which is free to rotate on its axis. The parts are shewn in Fig. 1 in the
positions they assume before action has commenced.
Directly the mercury touches the first wire a of the scale the current passes
through the corresponding plate a¹ and the spring arm B to an electro-magnet C,
which by attracting its armature rocks the bell crank lever D, E, F, and causes the
ratchet wheel G to advance one tooth and with it the ebonite disc A. At the
same moment a tail-piece of the bell crank lever D, E, comes in contact with the
blade I and directs the current of electricity in the line through the two parts in
contact K, L.
The ebonite dise A during the movement of rotation which it has just undergone

page_text: has displaced the first plate a³, and another plate 61 has come to take its place
beneath the spring arm B connected with the electro magnet C. The circuit but
recently completed by the first wire a of the scale is thus broken, and will not be
again completed till the mercury in the manometer has reached the level of the
second wire b, and so on.
It should be remarked that the mercury may fluctuate, even descend below the
level of the first wire a, and anon regain that level, but it will not be able to
complete a circuit with that wire during the whole of the remainder of the
operation.
The same motion is repeated each time the mercury reaches a new wire up to
the time when the movement of the clockwork contact distributor effects the
liberation from compression of the india rubber tubes by means of a current which
is made to pass into the electro magnet M, which acting upon its armature will lift
the pawls F and O. The ebonite disc A thus set free, and being rotated by
a weight P, will then return to its normal position in which it is arrested by a
stop Q.
At the same time the circuit is broken for a moment at K, L, lest the mercury
after its fall, and before it has regained its normal level, should come again into
contact with the wires a or b by any rapid fluctuations.
A modified form of transmitting apparatus is shewn in Fig. 2. In this arrange-
ment the plates are fixed and disposed in a circle and similarly mounted in ebonite,
whereas the spring B is carried by the disc and ratchet wheel. The first platinum
wire a of the manometer is in communication as before with the first plate a¹, the
second wire b with the second plate b¹, and so on. The manometer is arranged in
such a manner that the mercury cannot be forced out in case of the mixture on
being tested proving explosive.
The action of the apparatus is as follows:-The bellows act once every quarter
of an hour, and draw in the air of the mine by the tube A by six inspirations
and six expirations. This operation is amply sufficient to completely change the air
of the small combustion chamber. About 1 minute afterwards a knife-edged stop
placed on the circumference of a disc operated by clockwork (see the Drawing of
the mechanism Z at the right hand of Fig. 2) strikes against the tail of a platinum
lever 2, and causes it to describe an are over a circle of ivory on which are
mounted 3 platinum contact plates 1, 2, 3. The first contact of short duration
closes the circuit of an electro magnet Y and locks the tubes of rubber; the second
contact, which last 15", conducts the current into the platinum wire of the com-
bustion chamber A and heats the wire to redness. The pointer then takes a minute
to reach the third contact plate, which is also connected with the combustion
chamber A, and heats the platinum a second time to redness for another 15".
The knife-edged stop on the circumference of the disc releases the pointer,
which drawn back by the spring strikes against a stop R and reverts to its
normal position. The knife-edged stop then takes 10 minutes to reach a second
ivory quadrant, and it is during this time that the transmitter operates. The
second ivory quadrant is provided with 2 platinum contact plates. The first of
these 5 closes the circuit of an electro magnet X and releases the tubes of rubber.
Instead of breaking the line in K, L, as above explained, it is preferable to utilize
the movement of the armature of this electro magnet to break contact until the
mercury of the manometer has regained its normal level (see Fig. 2, K¹, L').
The second contact 4 directs the currents into the electro magnet M and
brings back the spring arm B to the left hand side of the first plate a¹ on the
ebonite disc.
The reason should here be explained why the platinum wire in the combustion
chamber is preferably twice heated to redness during 15" with an interval, of one
minute. The wire suddenly brought to a very high temperature causes the gas
enclosed in the chamber to expand instantly, and a portion thereof being driven
back into the manometer escapes combustion. During the minute devoted to the

page_text: cooling of the wire the gas which had previously escaped combustion passes back
into the chamber, where it is then consumed.
By locking the rubber tube which connects the chamber with the manometer
complete combustion of the gas might be obtained with a single heating of
the platinum wire, but the chamber would then be liable to burst in presence of
a mixture of an explosive character. It is to avoid such an accident that the
communication between the chamber and the manometer is left open.
The receiver of the apparatus is almost identical with the transmitter above
described.
The plates are numbered from 1 to 9, and indicate from 1 to 9 per cent. of fire-
damp.
By doubling the number of plates, or by quadrupling them, as well as the
platinum wires of the manometer, as high a percentage as 25 or 50 if desired may
be indicated, but as a rule the indication of 1 per cent. is quite sufficient for an
automatic apparatus working regularly once every hour.
The numbered plates of the receiver are also provided with contact points in
order to sound a continuous alarum whenever the proportions of the gaseous
mixture approach the limit which it is undesirable to exceed.
This receiver may be placed in a central office, in the engine room for instance,
and thence warnings may be issued in as many directions as desirable.
Each time that the mercury of the manometer in the analyzing apparatus reaches
a fresh division the needle of the dial of the receiver will give a corresponding
indication. The fluctuations which the mercury may experience will however not
be recorded, since each platinum wire can only transmit the current a single
time.
The return to 0° of the receiving apparatus after each test is effected automatically
by clockwork placed near the receiver.
The complete apparatus requires two Leclanché batteries (or other batteries
serving the same purpose) one for the test apparatus, the other for the receiver.
This second battery will be placed outside the mine.
Fig. 3 represents the general position of the test apparatus with respect to the
distribution of the currents of electricity, the letters, and figures thereon referring
to the same parts as in the two preceding Figures.
Contact No. 1 of the disc moved by clockwork closes the circuit of the electro
magnet Y and locks the tubes of india rubber; contacts 2 and 3 heat the platinum
wire to redness; contact 5 frees the tubes and breaks contact for a moment
at K, L; contact 4 replaces the pointer B on the edge of the plate a²; and, finally,
the plates H, I, send the current in the main line.
It may be as well to indicate' in conclusion the arrangements which should be
made to keep in action 4 of these apparatus in different galleries of a mine by the
aid of a single connecting line.
It will suffice this purpose to set the clocks of the four test apparatus each
15 minutes fast of the other. Thus, for example, the first will mark 9 o'clock, the
second 9 o'clock in fifteen minutes, the third 9 o'clock in thirty minutes, and the
fourth 9 o'clock in forty five minutes after the first.
The regulating clock of the central receiver will effect the return to zero every
quarter of an hour.
For 5 apparatus the return to zero would require to be effected every 12 minutes.
Five is the maximum number of test apparatus which could be established by the
aid of a single wire.
The setting of the clocks of the test apparatus when several are employed would
take place every morning by means of a simple arrangement of mechanism which
is not shewn in the Drawings, and to which no claim for novelty is made.
The apparatus above described may be employed for obtaining a quantitative
analysis of the gaseous impurities contained in the atmosphere of public buildings,
concert halls, and theatres, thus providing against accidental escapes of gas.

page_text: Having now set forth the nature of the said Invention of "Improved Apparatus
for Testing and Indicating the Presence and Percentage of Combustible Gases in
Air, such Apparatus being especially Applicable to the Detection of Fire-damp in
Coal Mines," as communicated to me by my foreign correspondent, and having
explained in what manner the same may be carried into effect, I wish it to be
understood that I claim,-
First. The arrangement of automatic testing apparatus, substantially as herein
shewn and described, whereby the presence and percentage of combustible gases in
air may be ascertained and indicated, such apparatus being especially applicable to
the detection of fire-damp in coal mines.
Secondly. The combustion chamber and manometer constructed and arranged in
the manner and for the purpose substantially as herein shewn and described.
Thirdly. The special arrangement of mechanism for automatically locking and
releasing the flexible tubes containing the gaseous mixture to be tested.
In witness whereof, I, the said Arthur William Lovell Reddie, have hereunto
set my hand and seal, the Twenty first day of July, in the year of our
Lord One thousand eight hundred and eighty one.