Improved Apparatus for the Detection of Explosive Gases in Mines or other Places.
Year: 1887

page_text: Date of Application, 4th Mar., 1887
Complete Left, 5th Dec., 1887
Complete Accepted, 6th Jan., 1888
TRUVIDIONAL SPECIFICATION.
Improved Apparatus for the Detection of Explosive Gases in Mines
or other Places.
I, JOSEPH WILSON SWAN, of Lauriston, Bromley, in the County of Kent,
Gentleman, do hereby declare the nature of this Invention to be as follows:--
The object of my Invention is to provide a simple and efficient indicator or detector
of explosive gases in mines or other places.
The apparatus constructed according to my Invention consists of a transparent or
translucent glass tube or chamber open at both ends except that the ends are covered by
wire gauze.
In this tube or chamber there is a metallic wire preferably of platinum or
of an alloy of platinum and Iridium so arranged that by means of a switch it can be
either included in or excluded from the circuit of a battery or generator of electricity
which forms part of the apparatus. The switch may be either separate from the
indicator or by fixing the indicator on a central pivot and arranging the electric
contacts in suitable positions, it may (by moving it round on its pivot) itself be made
to switch the current on or off.
I prefer to enclose the tube or chamber containing the indicator wire in a casing of
ebonite or other protecting material with an opening in one side for observing the
wire. Tho wire gauze diaphragms which cover the ends of the glass tube or chamber
are preferably circular and are held in their place by rings which screw within the
projecting ends of the casing and nip them upon the ends of the glass tube, or upon
shoulders formed in the casing in the same manner in which the objectives and
opera-glasses are held in their cells.
In using the apparatus I turn on the electric current by means of the switch and
observe the degree of brightness of the indicator wire. I then close the ends of the
tube or chamber (which can be conveniently done by the finger and thumb) and I
notice whether or not there is any change in the degree of brightness of the wire
when the ends of the indicator tube are closed, and if necessary, 1 repeatedly open
and close the ends of the tube. This will give the required indication, as, if fire-
damp or the like be present, the wire will be brighter when the indicator tube or
chamber is open than it is when closed.
. Dated this 4th day of March 1887
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, W.C.,
Agents for the said Joseph Wilson Swan.

page_text: COMPLETE SPECIFICATION.
Improved Apparatus for the Detection of Explosive Gases in Mines
I, JOSEPH WILSON SWAN
Gentleman, do hereby declare
the same is to be performed to
the following statement :-
or other Places.
of Lauriston, Bromley, in the County of Kent
the nature of this Invention and in what manner
be particularly described and ascertained in and by
The object of my Invention is to provide a simple and efficient indicator or detector
of explosive gases in mines or other places.
The apparatus constructed according to my Invention consists of a tube or chamber
in whole or in part transparent or translucent, and with openings therein covered by wire
gauze. In this tube or chamber there is a wire preferably of platinum or of an alloy
of platinum and Iridium so arranged that by ineans of a switch it can be either
included in or excluded from the circuit of a battery or generator of electricity which
preferably forms part of the apparatus and also if so desired part of a miner's electric
lamp. The switch may be separate from the indicator but preferably the indicator is
provided with a pivot in connection with electric contacts so arranged that by moving
the indicator round on the pivot the indicator itself acts as a switch to put the current
on or off.
I prefer to enclose the tube or chamber containing the indicator wire in a casing of
ebonite or other protecting material with an opening therein through which to observe
the wire. The wire gauze which covers the openings of the tube (when a tube is
used) may be circular and be held in its place by rings which screw within the
projecting ends of the casing and nip them upon the ends of the tube or upon
shoulders formed in the casing in the manner in which the objectives of opera glasses
are held in their cells.
In using the apparatus I turn on the electric current by means of the switch and
observe the degree of brightness of the indicator wire. I then close the tube or
chamber which can be done for example by the finger and thumb or by means of a
cover or covers provided for the purpose and I notice whether or not there is any
change in the degree of brightness of the wire from that displayed when the ends of
the indicator tube were closed and if necessary I repeatedly open and close the tube
or chamber. This will give the required indication as if fire damp or the like be
present the wire will be brighter when the indicator tube or chamber is open than
it is when closed.
The indication may be obtained by comparison of the degrees of luminosity of the
same wire when exposed to different atmospheres or by comparison with a standard
wire provided for the purpose and enclosed in a glass to which the atmosphere cannot
gain access.
The wire gauze whilst admitting the external air to the tube or chamber prevents
back firing in the event of the external air being explosive.

page_text: I will now describe arrangements according to my Invention with reference to the
accompanying drawings.
Figure 1 is a sectional elevation Figure 2 a plan and Figure 3 a back elevation
of a simple form of apparatus constructed according to my Invention and the
remaining figures illustrate modifications hereinafter described.
Referring to Figures 1. 2 and 3-A is a glass tube the open ends of which are
covered with discs of wire gauze a maintained in position by rings b screwed into the
projecting ends of the outer casing B (which is preferably of Vulcanite) so as to
confine the said discs between them and the ends of the tube A.
In the tube A is a platinum wire c attached at its opposite ends to two wires d, d²,
extending across the opposite ends of the tube and making contact with the
wires d, d³ leading to a boss or pivot projection e at the back of the casing B upon
which projection the apparatus can act as a switch by being turned in an opening or
socket provided in the support into. which the wires from the battery are led such
support being conveniently the casing of a Miner's Electric Lamp. The wires d' d³
are exposed on opposite sides of the small projection to make and break contact
with the wires leading to and from the battery. These latter wires are shewn at ƒƒ³
in figure 3.
When the apparatus is turned into the position shewn in full lines in figure 3 the
wires d d will make contact with the wires ff whereby the battery circuit will be
completed, the current passing through the wire c so as to cause it to become
red hot.
When the apparatus is turned into the position shown by the dotted lines, the
circuit is broken as the wires d¹³ are then out of contact with the wires ff. To
ascertain whether or not there be fire damp or like gas mixed with the atmospheric
air the apparatus is turned so as to complete the circuit, the ends of the casing B
being closed by the finger and thumb or in other convenient manner so as to prevent
entry of fresh supplies of the gaseous atmosphere and the degree of luminosity of the
wire c under these conditions is observed.
C
The ends of the casing B are then opened or uncovered whereupon the outer air
will enter the tube A through the wire gauze a and should fire damp be present
therein the wire c will become more luminous but if there be no explosive gases
present the degree of luminosity will remain the same as when the ends of the
casing B were covered.
Instead of the vulcanite casing B herein before described the tube A may be enclosed
in a metallic box as shewn in figures 4 and 5 which represent (drawn to an enlarged
scale) in vertical section and horizontal section respectively an arrangement of this
kind. A is the glass tube containing the platinum wire c and B is the metal box in
which it is secured by spring clips g. The box B is provided with a glass lid or
cover C through which the wire c may be seen. The rim or periphery of the box
is perforated or provided with openings covered by wire gauze a. On the exterior
of the rim is fitted to turn an outer rim k provided with openings or perforations /
corresponding to the openings i in the rim h so that by turning the outer rim k the
openings i may be opened and closed as required. The rim k is maintained in position
on the rim h by screws or projections m in the former entering slots in the latter
or vice versa.
The platinum wire c in the tube A is connected by one of its ends to one pole of a
battery by the wire p passing through an insulated hole in the box B whilst the
opposite end of the said platinum wire is connected to a spring contact piece q
(carried on the insulating pillar or stand r) which by turning the outer rim k is caused
to make or break contact with the said ring which has connected thereto a wire leading
to the other pole of the battery. When the outer rim is in the position shewn in
the drawing, the circuit is broken as the contact spring 9 is out of contact with the
rim k the end of the spring 9 entering a recess. n formed in the said rim as shewn
in figure 4.
By turning the rim k on the rim h so as to cause the springig to make contact with
the rim k but without uncovering the openings i in the box B the circuit through the

page_text: battery will thus be completed and the wire will become red hot. The degree of
luminosity of the hot wire is observed and then the rim k is further turned so as to
cause the holes therein to come opposite or correspond to the openings in the rim h
when the outer air enters the apparatus and if there be fire damp or other similar gas
present therein the luminosity of the wire will be increased. a are openings in the
tube A for allowing the air admitted to the apparatus to gain access to the
platinum wire.
In order to more readily estimate the amount of increase in luminosity of the wire
in the tube A caused by the presence of fire damp in the air to be tested an additional
tube may be fitted in the box B as shewn in Figures 6 and 7 which additional tube A³
contains a platinum wire c* (similar to the wire in the adjacent open tube) but is
entirely closed at both ends so as to exclude the external atmosphere. One end of the
wire is connected to one pole of the battery by the wire f and the opposite end of
the said wire c is connected by the wire to one end of the wire c in the tube A the
opposite end of which latter wire is connected to the contact spring 9 hereinbefore
described. The other parts illustrated are substantially the same as those herein-
before described and are marked with the same reference letters. In this case when
the battery circuit is completed, both of the wires c and c² will become luminous and
if there be no fire damp present in the air both wires will be equally luminous
but should there be fire-damp present in the air the exposed wire c will become
more luminous than the wire (to which the mixture of air and fire-damp cannot
gain access) and thus the difference in the degree of luminosity of the two wires c
and will indicate the presence in the air of explosive gas.
с
Having now particularly described and ascertained the nature of my said Invention
and in what manner the same is to be performed I declare that what I claim is :-
First An apparatus for use for indicating the presence of fire damp in the air of
coal mines or other places consisting in a transparent or translucent tube or chamber
enclosing a wire in the circuit of a battery or other generator of electricity and
provided with wire gauze substantially as hereinbefore described.
Second-The several arrangements of the said apparatus substantially as and for
the purpose hereinbefore described and illustrated in Figures 1, 2 and 3 in Figures 4
and 5 and in Figures 6 and 7 of the accompanying drawings.
Third In apparatus for use for indicating the pressure of Fire damp or similar
gas in the air of coal mines or other places a pivot or stem carrying the contacts for
the indicator wire to be rendered luminous and acting as a switch in a socket into
which the wires or conductors to and from a battery or generator of electricity are led
substantially as hereinbefore described and illustrated in Figures 1, 2 and 3 of the
accompanying drawings.