Improved Method of and Apparatus for Detecting and Indicating the Presence of Firedamp in the Atmosphere of Mines and other Places.
Year: 1896

page_text: Date of Application, 26th Oct., 1896
Complete Specification Left, 25th Aug., 1897-Accepted, 16th Oct., 1897
'PROVISIONAL SPECIFICATION.
Improved Method of and Apparatus for Detecting and Indicating the
Presence of Firedamp in the Atmosphere of Mines and other
Places.
I, ERHARD LUDWIG MAYER, of 11 Billiter Square, in the City of London,
Engineer, do hereby declare the nature of this invention to be as follows:-
For detecting and indicating the presence of fire damp in the atmosphere of
mines and other places I cause such gas or' gases to generate electricity by means
of a gas battery and utilise such electricity to operate or control means or apparatus
whereby a visual or audible signal, or both a visual and audible signal are brought
into operation to give an indication of a change in the constitution of the atmo-
sphere in which the battery is placed.
For this purpose, the presence of fire damp may, according to this invention be
detected and indicated by causing such gas or gases to generate by means of a gas
battery an electric current, which, by means of a galvanometer or other suitable
apparatus capable of being actuated by a weak electric current, is caused to pro-
duce a signal or to control, either directly, or indirectly, as by the aid of a relay
another electric circuit by which an audible or visual signal, or both an audible
and visual signal will be produced.
As will be obvious, apparatus to operate on the principle of my invention can
be constructed in various forms.
In one arrangement the gas battery comprises one or more pairs of elements
consisting or each consisting of two coiled strips of platinum that are preferably
coated with black or spongy platinum and are fixed in the ends of a bent tube con-
taining a suitable electrolyte, such as dilute sulphuric acid, into which the said
strips dip. A number of pairs of elements thus constructed may be fixed to a
suitable stand so that one of the elements of the pair or of each pair is located
within a closed chamber or receiver whilst the other is located in the external
atmosphere. When several pairs of elements are used, they are connected up in
series so that the inner element of one pair is connected to the outer element of the
next adjacent pair and so on. The arrangement is such that if fire damp be
brought into contact with the inner or outer element or set of elements whilst the
outer or the inner element or set of elements respectively be in contact with atmos-
pheric air of ordinary purity, an electric current will be set up. Suitable
apparatus for use with a gas battery of the construction described, or of other
suitable construction, is, according to one construction a galvanometer provided
with a movable contact that may be in the form of a small plate 'fixed to a
suitably counterbalanced arm carried by the fibre or filament from which an
astatic magnetic needle arrangement is suspended. In suitable proximity to this
movable contact is a fixed contact that may be adjustable relatively to the mov-
able one and is connected to one pole of an electric battery the other pole of which
is connected with the movable contact through any suitable means as for example

page_text: through a conducting liquid into which dips a conducting wire connected to the
movable contact and carried by the fibre or filament that carries the same, the
arrangement being such that the liquid conductor or other device will not inter-
fere with the free motion of the magnetic needle or needles and that upon the
movable contact being brought to bear against the fixed one, the circuit of the
battery will be closed and cause the operation of the audible or visual or audible
and visual signal, which may be of any suitable construction, to take place either
directly, or through a relay brought into action by the closing of the said circuit.
In some cases the galvanometer may be so constructed that the indicating needle
thereof when moved by the action of the current traversing the galvanometer will
be brought into contact with a conducting stop and so close the indicating electric
circuit.
. Instead of the current from the gas battery circulating continuously, or at
suitable intervals, through the galvanometer or its equivalent, it may be made to
charge a condenser, the discharge of which is sent through the galvanometer or
equivalent device from time to time for producing a signal.
As the force exerted by the displacement of the needle in a galvanometer or
equivalent device, as hereinbefore described, or in a quadrant electrometer as in
some of the arrangements of apparatus described in my former Specification,
(No. 18188 of 1895) is very small, it may happen that the electric current will
not pass between the movable and fixed contacts used for completing the circuit
of the signalling device, although such contacts are actually bearing against one
another. This difficulty is overcome according to this invention by coating the
adjacent surfaces of the contacts, or one of them, with a thick layer of spongy
metal, such for example as platinum, which may conveniently be done electroly-
tically. The contacts may conveniently be made in the form of small plates of
platinum each of about half a square inch in area. By the means described, when-
ever the contacts or plates come into close and parallel proximity to one another,
the attractive force set up between them, aided by the well known action of points,
invariably causes an effective contact between the said parts and the passage of
an electric current to take place. The use of spongy platinum or the like also
prevents the sticking together that sometimes takes place when two uncoated
platinum wires are used, due to some welding action of the electric current at the
point where it is passing from one wire to the other.
Dated this 26th day of October 1896.
Improved Method of and Apparatus for Detecting and Indicating the 4
Presence of Firedamp in the Atmosphere of Mines and other
Places.
I, ERIIARD LUDWIG MAYER, of 11 Billiter Square, in the City of London,
Engineer, do hereby declare the nature of this invention and in what manner the
same is to be performed to be particularly described and ascertained in and by the 4
following statement:
According to this invention, the presence of fire damp, that is to say marsh gas,
in the atmosphere of mines and other places is detected and indicated by causing
such gas to generate by means of a gas battery or gas cell, an electric current,

page_text: which, by means of a galvanometer or other suitable apparatus capable of being
actuated by a weak electric current, is caused to produce a signal, or to control,
either directly, or indirectly as by the aid of a relay, another electric circuit by
which an audible or visual signal, or both an audible and visual signal will be
produced.
As will be obvious, apparatus to operate on the principle of my invention can be
constructed in various forms.
In the accompanying drawings Fig. 1 shows diagrammatically, and by way of
example, one arrangement of apparatus according to this invention. Figs. 2 and
3 how a construction of gas battery suitable for use in such apparatus. Fig. 2
being a vertical section on the line of Fig. 3, and Fig. 3 being a horizontal
section on the line yy of Fig. 2. Fig. 4 is a diagram showing a modified form of
apparatus according to this invention.
The gas battery shown comprises three pairs of elements, each pair consisting
of two coiled strips 1 and 2 of platinum that are preferably coated with black or
spongy platinum and are fixed in the ends of a bent tube 3 containing a suitable
electrolyte, such as dilute sulphuric acid, (consisting for example of 4 parts of
water to one of acid) into which the said strips dip and in which they are suitably
supported. The pairs of elements thus constructed are fixed to a suitable stand 4
so that one of the elements, namely 2 in the example shown, of each pair is
located within a closed chamber or receiver 5 whilst the other, namely 1, is located
in the external atmosphere. When several pairs of elements are used, as in the
example shown, they are connected up in series so that the inner element 2 of one
pair is connected to the outer element 1 of the next adjacent pair and so on, by con-
ductors 6, the end elements being connected to two binding screws 6. The
chamber 5 is provided with inlet an qutlet pipes 5 and 5b respectively each pro-
vided with cock. By the arrangement described, if fire damp be brought into
contact with either the inner set of elements 2 or with the outer set of elements 1
whilst the outer set of elements 1 or the inner set of elements 2 respectively are in
contact with atmospheric air of ordinary purity, an electric current will be set
up when the circuit of the battery is completed. The number of gas cells or
pairs of elements can be varied according to the degree of sensitiveness desired.
In some cases a single cell or pair of elements is sufficient.
The detecting and indicating apparatus for use with a gas battery or gas cell
of the construction just described, or of other suitable construction, comprises,
according to the arrangement shown in Fig. 1, a galvanometer the coil 7 of which
is adapted to be placed in circuit with the gas battery represented at A in Fig. 1.
This may advantageously be done at short intervals, say every 15 minutes, by a
movable contact lever 8, which is connected to one pole of the gas battery, and is
rotated by a clockwork or other suitable motor at 9. This lever is adapted, during
its rotation, to come into connection with a fixed contact 8ª connected, through the
galvanometer coil, with the other pole of the gas battery and so temporarily
complete the circuit of the said battery through the coil. The galvanometer has a
movable contact 10, preferably in the form of a small plate fixed to a suitably
counterbalanced curved metal arm 11 which is carried by the fibre or filament 12
from which an astatic magnetic needle arrangement 13 is suspended and which
serves also as a pointer or indicating needle. In proximity to the contact 10 is a
normally fixed contact 14 which is connected to one pole of an electric battery 15
the other pole of which is connected with the movable contact 10 through any
suitable means, as for example through a hair spring, or, as shown, through a
conducting liquid 16 into which dips a conducting wire 17 that is carried by the
fibre or filament 12 and is in electric connection with the movable contact 10 through
the arm 11. The arm 11 may be a magnet and form part of the astatic needle
arrangement 13, in which case the electric connection between contact 10 and
wire 17 may be made by a separate wire carried by the said arm. In any case,
the arrangement is such that the liquid conductor 16 (or its equivalent) will not
interfere with the magnetic-needle or needles 13 being freely deflected when the

page_text: coil 7 is traversed by an electric current from the gas battery A, and that upon
the movable contact 10 being thus brought to bear against the fixed one 14, the
circuit of the battery 15 will be closed and cause the operation of an audible or
visual signal, or audible and visual signal (which may be of any known or suitable
construction) to take place, either directly, or through a relay brought into action
by the closing of the said circuit. In Fig. 1, a relay 18 is employed to close the
circuit of the battery 15 through the signalling device 20 which is represented as
an electric bell.
In Fig. 1, the circuit of the battery 15 is arranged to be completed in the first
instance through the winding 18 of the relay, fixed spring contacts 19, 19", and
a movable contact strip 19b carried by a rotary switch disc 19. The switch disc
has a constant tendency to partly rotate and bring the contact strip 19 into
electrical connection with two spring contacts 19 and 19e connected to the opposite
poles of the battery 15, on one side through the electric bell 20. The switch disc
is normally held in the position shown by a detent 21 on the armature 21" of an
electro-magnet 21b the winding of which is in electrical connection with one. pole
of the battery 15 through the contacts 19", 19 and 19 and is adapted, by the opera-
tion of the relay, to be placed in connection with the other pole of the said battery
through the fixed contact 18" and relay armature contact 18. When this takes
place by contacts 10 and 14 coming together, the electro magnet 21' is energized,
the armature 21 is attracted, and the switch disc 19" is released and allowed to
partly rotate in the direction of the arrow with the result that the relay circuit
will then be opened and the battery circuit closed through the contacts 194, 19,
19° and the bell 20 which will be kept sounding until the switch is reset.
The contact 14 may conveniently be carried by a movable ring 14" which is
adjustable about its centre so as to enable the distance apart of the two contact
plates 10 and 14 to be varied to suit requirement and also to ensure that these two
plates shall be parallel to each other when brought together. With a gas battery
of the kind shewn the winding of the galvanometer may have a resistance of about
100 ohms.
As the force exerted by the displacement of the needle in a galvanometer (or
equivalent device) as herein before described, or in a quadrant electrometer as in
some of the arrangements of apparatus described in the Specification of a former
Patent No. 18188 of 1890, is very small, it may happen that the electric current
will not pass between the movable and fixed contacts (10 and 14) used for complet-
ing the circuit of the signalling device, although such contacts are actually bearing
against one another. This difficulty is overcome by coating the adjacent surfaces
of the contacts, or one of them, with a thick layer of spongy nietal, such for
example as platinum, which may conveniently be done electrolytically.
The contacts may conveniently be made in the form of small plates
of platinum each say of about a quarter of a square inch in area. By the means
described, whenever the contacts or plates come into close and parallel proximity
to one another, the attractive force set up between them, aided by the well known
action of points, invariably causes an effective contact between the said parts and
the passage of an electric current to 'take place. The use of spongy platinum or
the like also prevents the sticking together that sometimes takes place when two
uncoated platinum wires are used as contacts, due to some welding action of the
electric current at the point where it is passing from one wire to the other.
As will be obvious a galvanometer or device adapted to be set in motion by a
weak electric current can be constructed in various forms other than that shown.
Instead of the current from the gas battery circulating at suitable intervals
through the galvanometer or its equivalent, it may be made to charge a condenser
which is discharged from time to time, and the resulting current sent through the
galvanometer or equivalent device for producing a signal.
Fig. 4 shows an arrangement of this kind in which 22 and 22 are the plates
of a condenser adapted to be connected to the poles of the gas battery A so that
they will be oppositely charged with static electricity when the gas battery is

page_text: excited by the presence of fire damp. The plate 22 is connected to one pole of the
gas battery A by a conductor 23 and also to one end of the galvanometer coil 7
by a conductor 23. Plate 22" is connected to a spring contact 24 which normally
bears upon a fixed contact 24" connected to the other pole of the gas battery. The
spring contact is adapted at intervals, as by a pin 25 on a wheel 26 driven by
clockwork, to be moved from the contact 24" and caused to bear against a fixed
contact 27 connected to the other end of the galvanometer coil 7.
29 is a contact piece or strip carries by the wheel 26, and 30 and 31 are two
spring contacts connected to the opposite poles of the gas battery and adapted to
simultaneously bear upon the contact when the same is brought opposite to them
by the piece 29 on rotation of the wheel 26. As will be seen the arrangement is
such that with the parts in the position shown the wheel 26 rotating in
the direction of the arrow, and assuming the gas battery to be excited by the
presence of fire-damp, the condenser will be charging. As the pin 25 moves down-
ward it will act against the conitact lever 24 and move it from the contact 24 thus
interrupting the circuits of both the gas battery and condenser, until the lever 24
bears upon contact 27 whereupon the condenser will be discharged through the
galvanometer. As the wheel continues to rotate the contact strip 29 will shortly
after the discharge of the condenser come into connection with the two contacts 30
and 31 and short circuit the gas battery until the contact strip leaves the said
contacts, after which the charging of the condenser will again take place.
It will be seen that the connection between the condenser plates and the gas
battery will be broken before the plates are discharged through the galvanometer
coil, so that the discharge current sent through the said coil will be independent
of the action of the said battery. The current passing through the coil 7 acts in
the manner hereinbefore described to complete the circuit of a lattery 15 through
a tignalling device 20, either directly as shewn in Fig. 4, or indirectly through a
relay as shown in Fig. 1.
In carrying the invention into practice, the gas hattery is arranged in the mine
or other place in which the presence of the fire-damp is to be detected and
indicated, and connected by insulated leads to the galvanometer or equivalent
device which is arranged at the surface of the mine or other desired place.
In order that the efficiency of the apparatus shall be maintained unimpaired for
a long time, the marsh gas after acting upon the one electrode or set of electrodes
in the gas cell or cells should be withdrawn therefrom and be replaced by air of
ordinary purity.
To enable this to be done the gas cell or battery shewn in Figs. 2 and 3 may be
enclosed in an air tight receptacle through which air from the mine or other place
likely to contain marsh gas, and air of ordinary purity from the atmosphere
external to the mine or other place are alternately drawn or forced by a suitable
pump or pumps, so as to come successively into contact with the electrodes 1 of the
gas cells (Figs. 2 and 3) the box 5 enclosing the other electrodes 2 then containing
air of ordinary purity.
Having now particularly described and ascertained the nature of the said in-
vention and in what manner the same is to be performed I declare that what i
claim is :-
1. The herein described method of detecting and indicating the presence of
fire-damp in the atmosphere of mines and other places by causing such fire damp
to generate by means of a gas battery or gas cell, an electric current and utilizing
such electric current by means of a galvanometer or equivalent apparatus capable
of being actuated by a weak electric current, to produce a signal, or to control,
either directly or indirectly, another electric circuit by which a signal will be
produced, as set forth.
2. For carrying out the method referred to in the preceding claim apparatus
arranged and operating substantially as hereinbefare described.
3. In apparatus for detecting and indicating the presence of fire damp in mines

page_text: or other places the combination of one or more gas cells capable of generating
electricity when subjected to the simultaneous but separate action of the said fire
damp and air of ordinary purity, and a galvanometer or other equivalent apparatus
capable of being actuated by the passage through it of a weak electric current
generated by the gas cell or cells and to produce a signal, or to control another
electric circuit by which a signal will be produced as set forth.
4. The modified arrangement of the apparatus in which there is arranged
between the gas battery or gas cell and the galvanometer or other device capable
f being actuated by a weak current, a condenser which is discharged at intervals
through the galvanometer or equivalent device to produce a signal substantially
as hereinbefore described.
5. In apparatus for detecting and indicating the presence of fire damp the use in
conjunction with contacts the force for moving which into electrical connection
with each other is small, of spongy metal such as platinum applied as a coating to
the said contacts, substantially as and for the purpose specified.
6. For detecting and indicating the presence of fire damp in the atmosphere of
mines or other places, apparatus constructed, arranged and operating substantially
as hereinabove described with reference respectively to and shown in Fig. 1 and in
Fig. 4 of the accompanying illustrative drawings, whether or not the galvano-
meter acts directly or indirectly. through a relay, to produce a signal.
7. In apparatus of the kind herein specified, a gas battery comprising one or
more pairs of elements consisting or each consisting of two strips of platinum
located in the ends of a tube fixed to a base or support and containing a suitable
electrolyte, one of the elements of the pair or of each pair being located within a
closed chamber whilst the other element of the pair or of each pair is located in the
atmosphers external to the closed chamber so that one of the elements of the pair
or of each can be brought into contact with the atmosphere to be tested and the
other with atmospheric air of ordinary purity, substantially as hereinbefore
described with reference to and shown in Figs. 2 and 3 of the accompanying
illustrative drawings.
Dated this 25th dom of
1007
For the Applicant,
W. LLOYD WISE,
46 Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.