IMPROVEMENTS IN MINERS' SAFETY LAMPS
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by the said Dougald Ballardie at the
Office of the Commissioners of Patents on the 16th December 1882.
DOUGALD BALLARDIE, of Glasgow, in the County of Lanark, North Britain
"IMPROVEMENTS IN MINERS' SAFETY LAMPS
"
This Invention has for its object the construction of miners' safety lamps in an
improved manner and so as whilst yielding abundant light to be quite safe. The
Invention also comprises improved means for locking safety lamps and for
preventing their being tampered with.
A safety lamp as made with the improvements comprises an oil vessel which
forms the base and which has a wick tube extending up from it through an air
chamber into the light chamber. A diaphragm of wire gauze separates the light
chamber from the air chamber, and forms the top of the latter, but has at its
middle an opening through which the wick projects and which has fixed over it a
shield or burner. Round the lower part of the air chamber there are a number of
inlets for air but these are covered with wire gauze, and the air entering the
chamber has access thence to the flame between the wick tube and burner and also
through the wire gauze top of the chamber. The light chamber is encircled by a
glass shell of a general cylindrical form but varying in thickness so as to have the
form of double-convex lens in vertical section. The glass shell or cylinder is held
between a bottom ring and a cap which are connected by strong wires or rods; and
the cap has openings formed round it and covered with wire gauze for the escape
of the gaseous products of combustion. Over the flame there is provided a metal
funnel by which a good draught through the lamp is secured and a good light is
obtained, this funnel being fixed in a metal diaphragm secured in the lower part of
the cap. The light chamber or upper part of the lamp is secured to the air
chamber or lower part by a bayonet joint and when the parts are closed and
turned into the proper positions relatively to each other a perforated projection on

page_text: one part coincides with a similar projection on the other part and a lead rivet is
passed through and is riveted by means of a strong lever compresser, which may at
the same time emboss a number or other mark on the rivet head. A cutting
instrument is provided for removing the rivet heads when the lamp is to be opened
and the rivet shank then drops out being made of a tapering form for that
purpose.
In the event of the atmosphere in which the lamp is held being explosive the
small quantity of gas in the air chamber explodes and the expanded gases pass up
through the burner and extinguish the light but no flame passes back through the
wire gauze at the apertures through which the air enters the lamp. The lamp
may be arranged to give warning by a bell or by means of an electric current
extending any distance whenever the atmosphere in which it is placed becomes
explosive. For this purpose a thread of cotton or other easily burned material is
stretched once or oftener across the interior of the air chamber and is made to hold
a spring detent which may be connected to a bell on the lamp or which may be
arranged for making contact in an electric circuit. Then whenever the gas ignites
in the air chamber it will burn the thread and release the spring detent and the
spring will cause the bell to be struck or the electric circuit to be established so as
to ring a bell or make some other warning signal at a distance.
The lamp is designed for burning paraffin oil and it is preferred to use what is
known as lighthouse oil in it but any good burning oil can be used in it.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Dougald Ballardie in the Great Seal Patent Office on the 15th June
1883..
DOUGALD BALLARDIE, of Glasgow, in the County of Lanark, North Britain
"IMPROVEMENTS IN MINERS' SAFETY LAMPS "
My said Invention has for its object the construction of miners' safety, lamps in
an improved manner and so as, whilst yielding abundant light, to be quite safe.
My Invention also comprises improved means for locking safety lamps, and for
preventing their being tampered with.
A safety lamp as made with my improvements comprises an oil vessel which
forms the base, and between which and the light chamber there is an air chamber.
The light chamber is encircled by a glass shell and the air for combustion has
access only through the air chamber which has its inlet orifices covered with wire
gauze and which is separated from the light chamber by a wire gauze diaphragm.
In the event of the atmosphere in which the lamp is held being explosive the
Sinall quantity of gas in the air chamber explodes and the expanded gases pass up
through the burner and extinguish the light but no flame passes back through the
wire gauze at the apertures through which the air enters the lamp.
The lamp may be arranged to give warning by a bell or by means of an electric
current extending any distance whenever the atmosphere in which it is placed
becomes explosive. For this purpose a thread of cotton or other easily burned
material is stretched once or oftener across the interior of the air chamber and is
made to hold a spring detent which may be connected to a bell on the lamp or
which may be arranged for making contact in an electric circuit. Then whenever
the gas ignites in the air chamber it will burn the thread and release the spring
detent and the spring will cause the bell to be struck or the electric circuit to be
established so as to ring a bell or make some other warning signal at a distance.
Or the spring may be arranged simply to close the air inlets of the lamp.
My improved lamp is designed for burning paraffin oil, and I prefer to use what
is known as lighthouse oil or Young's No 1, burning oil in it, but any good burning
oil can be used in it.
And in order that my said Invention and the manner of performing the same.
may be properly understood I hereunto append a sheet of explanatory drawings
to be hereinafter referred to and representing a miner's safety lamp as made with
my improvements.
Figures 1 and 2, on the accompanying sheet of drawings are an elevation and a
vertical section of the lamp. Figure, 3, is a plan; figure, 4, is a plan of the
diaphragm which separates the air chamber from the light chamber; and figure, 5,
is a sectional plan showing the interior of the air chamber. In these drawings the
same reference numerals are used to mark the same or like parts wherever they
are repeated.
An oil vessel, 6, forms the base of the lamp and has screwed into it a box, 7, which
has fixed in and passing through it the wick tube, 8. The pinion, 9, for raising
the wick is arranged in the box, 7, its spindle passing through a small hole in the
side to an external button, 10. The wick tube, 8, is for a part of its length encased
in an outer tube, 11, which is fixed in the top of the box, 7, and this box, 7, is
closed at both top and bottom so as to shut off all communication with the outside.
Next above the box, 7, there is formed an air chamber, 12, having its lower part
in the shape of an inverted cone, 13, which is made with a number of inlet
apertures and is lined with wire gauze. The conical part, 13, has fixed to its top,

page_text: a ring, 14, to which there is fitted a movable ring, 15, forming the lower part of
the light chamber. The lower ring, 14, is formed with a slightly projecting flange
which is made with notches, 16, as shown in figure, 5, to adinit studs fixed to the
inside of the upper ring, 15, the combination forming a kind of bayonet joint for
connecting the upper and lower parts of the lamp. To the inside of the lower
ring, 14, there is fitted a dome-shaped diaphragm, 17, shown separately in figure, 4,
and consisting of a frame of sheet metal having wire gauze attached to it, with a
cone, 18, fixed in the middle. This cone, 18, has its bottom open to the air
chamber, 12, and it leads the air up and directs it upon the wick, the wick tube, 8,
extending up inside nearly to the top of the cone, 18.
The light chamber, 19, is encircled by a glass shell, 20, of a general cylindrical
form but is by preference made with a varying thickness so as to have the form of
a double convex lens in vertical section. The glass shell, 20, is held between the
bottom ring, 15, and a cap, 21, which are connected by strong wires, 22, packings
of asbestos being inserted between the upper and lower edges of the glass and the
cap, 21, and ring, 15. The cap, 21, has openings formed round it and covered with
wire gauze for the escape of the gaseous products of combustion. Over the flame
there is provided a metal funnel, 23, by which a good draught through the lamp
is secured and a good light is obtained, this funnel being fixed in a metal
diaphragm, 24, secured in the lower part of the cap, 21. The top of the cap, 21, is
made double or with inner and outer shells, 25, 26, between which there is an air
space communicating with the outside only by a narrow opening.
The inner cap
shell, 25, has a layer of asbestos applied on the upper side of it, the arrangement
being such as to prevent the top or outer shell, 26, from becoming overheated.
When the upper part of the lamp has been closed down on the lower part, with
the studs on the ring, 15, entered into the notches, 10, and turned under the flange
of the lower ring, 14, perforated projections, 27, 28, on the rings coincide with each
other. The lamp is locked by passing a lead rivet, 29, through the projections,
27, 28 and riveting it by means of a strong lever compresser or other suitable
instrument. The riveting instrument may be made like a pair of punching pliers;
and the part for forming the head of the rivet may be formed with a screwed hole
to receive a changeable screw plug or type piece for embossing a number or other
mark on the rivet head. When the lamp has to be opened a common knife may
be used for removing the rivet head, and the rivet shank may then drop out being
made of a tapering form for that purpose; or it may be forced out by means of a
pair of punching pliers.
In the modification or example shown in the drawings the conical part, 13, of
the air chamber, 12, is made double, and when either part is turned upon the other
the air inlets become closed. The movable part is acted on by a blade spring, 30,
(figure, 5) fixed to the tube, 11, but this spring is ordinarily kept in a position to
hold the air inlets open, by a cotton thread, 31, which is stretched upon hooks in
the air chamber, 12, and made fast on an external pin, 32. When ignition takes
place inside the air chamber it burns the cotton thread, 31, and releases the
spring, 30, which instantly closes the air inlets.
Having thus particularly described my said Invention and the manner of
performing the same I have to state that I do not restrict myself to the precise
details herein described or delineated but that what I believe to be novel and
original and claim as the Invention secured to me by and in terms of the herein-
before in part recited Letters Patent is :-
.
1. The combination of parts constituting the improved miner's safety lamp
herein before described and shown in the accompanying drawings.
2. The constructing of a miner's safety lamp with an air chamber through which
the air for combustion must pass and of which the inlets are protected by wire
gauze whilst a diaphragm of wire gauze divides the air chamber from the light
chamber such diaphragm having fixed to its middle a cone or directing tube to lead
the air to the flame, the parts being arranged and operating substantially as herein-
before described.

page_text: 3. The combination of parts forming the top of the lamp and having as a
principal feature the metal funnel for concentrating the current or draught
substantially as hereinbefore described.
4. The arrangement of a spring in the air chamber to be held by a cotton or
other inflammable thread substantially as and for the purposes herein before
described.
5. The system of locking a miner's safety lamp with a lead rivet closed by means
of an instrument arranged to put a special mark on the rivet head substantially as
hereinbefore described.
.
In Witness whereof I, the said Dougald Ballardie, have hereunto set my
hand and seal this fourteenth day of June in the year of our Lord One
thousand eight hundred and eighty-three.
Witness
EDMUND HUNT
Patent Agent.
Glasgow.
DOUGALD BALLARDIE (L.S.)