IMPROVEMENTS IN APPARATUS AND MEANS FOR THE PREVENTION OF EXPLOSIONS IN COAL Mina EDINING FRA ΑΜΑΡΑΝΤΙΤΗΡΙΑ ΤΙ ΒΑΡΙΑΤ MINES ARISING FROM ATMOSPHERIC ELECTRICITY
Year: 1880

page_text: LETTERS PATENT to Thomas Canning and William Edgar Thomas, both of
Newport, in the County of Monmouth, for an Invention of "IMPROVEMENTS
IN APPARATUS AND MEANS FOR THE PREVENTION OF EXPLOSIONS IN COAL
Mina EDINING FRA
ΑΜΑΡΑΝΤΙΤΗΡΙΑ ΤΙ ΒΑΡΙΑΤ
PROVISIONAL SPECIFICATION left by the said Thomas Canning & William
Edgar Thomas at the Office of the Commissioners of Patents on the 3rd
November 1880.
THOMAS CANNING and WILLIAM EDGAR THOMAS, both of Newport, in the County
of Monmouth. "IMPROVEMENTS IN APPARATUS AND MEANS FOR THE PREVENTION
OF EXPLOSIONS IN COAL MINES ARISING FROM ATMOSPHERIC ELECTRICITY."
The first part of this Invention consists in fixing to and above the pithead
framing a roof the covering of which shall be a material which is a conductor of
electricity.
The second part of this Invention is the attachment of a lightning rod and
conductor having a perfect earth connection capable if struck by lightning to
receive the discharge and conduct it safely into the earth, and also to conduct any
discharge received by the roof in a similar manner to the earth.
The third part of this Invention consists in passing (without any inconvenience
or in any position) any wire rope or rod in motion or at rest, or any metallic
communication with the mine, through an instrument or apparatus of a very
simple character, which will render the wire harmless in respect to causing any
explosion, or giving forth a spark after it has passed through it. As a spark might
pass in the instrument or apparatus itself, an arrangement by means of pulleys
and a small water tank is provided, which would effectually guard against any
danger of gas, if any were present, being ignited.
The above being the main outlines of this Invention, I now proceed to describe
the details a little more fully.
Attached to a pithead framing is a wrought iron roof either insulated or not, and
to this is fixed a lightning rod and conductor. The roof is necessary because in

page_text: cases of forked discharge one fork might strike the pit head gearing and cause an
explosion by passing into the mine, while the other fork striking the conductor
would pass harmlessly into the earth. In the present case a bifurcated discharge
striking both conductor and roof is carried away to the earth; for the roof is a
conductor itself of electricity, and being in connection with the conductor proper
which leads to the earth, the whole charge passes safely away. To effect this the
better a metallic rod (iron, copper, or brass, or any conductor, but preferably copper)
is run along the ridge of the roof and all round its eaves, and put in connection
with the conductor.
The lightning rod is made of copper with a number of points, and the conductor
is a stout copper wire rope passing into the earth, where it is proposed to make a
good connection with the earth. As this is of the first importance, the inventors
contemplate connecting the conductor intimately and perfectly with a metallic
cylinder or vessel of any shape, or a plate, say, of copper, from which a number of
wires will be carried into damp clay or earth all around into an open pool of water,
an iron water main or other inain, or into a running stream or drain. It should
not be carried into a brick cistern or such construction. For greater safety it is
proposed to raise metallic points on the ridge of the roof, and add another or more
than one other conductor from the roof if shown by subsequent experiments to be
needed.
For such ropes, wires, or rods which do not come under the roof for the whole of
their course above ground, and which may therefore receive a lightning discharge,
the inventors have devised a simple instrument, before described in general terms
under the third clause of this Specification. The body of the instrument is in
shape like a tube, and can be fixed vertically or horizontally as required. There is
a bold fast which may be another stout tube acting as a bracket to pass through
the wall of the pit shaft or other construction to hold the main tube of the
instrument in its place. Through this tube the wire or rod in motion or rope
passes up and down or to and fro, as may be required. On the inside of this tube
or cylinder are a number of points approaching the wire but not interfering with
its motion. If electricity of higher tension be on the wire the points draw it off, a
series of sparks passing. To ensure the complete discharge of the wire rope, friction
pulleys or rollers with which it comes in contact are fixed at the points where it
enters and leaves the cylinder or tube. This instrument should be made sufficiently
stout and fastened in so well as to resist a wrench of wire rope in passing through
it. The tube should be copper, brass, or iron, or any other good conductor, the
points to be of the same material. The rollers and bearings to be brass or any
hard metal that is a good conductor. The tube which acts as holdfast, grip, or
bracket (whichever it may be called) may be iron, but the wires passing through
it connected with the points and main tube should all be of stout copper each
about one eighth of an inch in thickness (certainly not slighter). These wires are
to be brought in all directions into damp clay or other good earth connection. The
wire rope, after passing through this instrument, will be found free from all
electricity capable of doing any injury in the mine. The instrument can be made
as powerful as desired by increasing the number of friction rollers, points, and
conducting wires.
In cases where the passing of a spark might be dangerous, the inventors have
designed a narrow tank with a pulley fixed on a spindle running across the tank,
and another pulley geared on the outer side of the tank. The tank itself may be
supported on strong brackets, or by other means, as found convenient, against a
wall if need be, or in the earth, or bolted down to a bed. The tank and pulleys
may be of iron or any strong metal, and should be made as strong as the necessities
of the case require, for a hauling rope to be of very great strength, for example.
As metal takes less room it is preferable to wood or any other material, though the
material is of no consequence provided the tank be strong and water-tight, and
the instrument before described employed. The instrument referred to above is
fixed in this tank precisely as before described, the conductor having a good earth

page_text: connection. The tank is kept filled with water, say, by some self supplying process,
which may be easy to adopt according to circumstances. The wire passes through
the water into the instrument as before, then passes round the bottom pulley, and
over the pulley at the top of the tank. As gas cannot enter the water in the tank,
and as the instrument for discharging the wire or rope is under the water at all
times, there can be no danger.
The water and the metallic tank pulleys themselves help in discharging the
wire, and might in certain cases be found nearly sufficient. As the tank may be
made very narrow it can be fixed in any pit shaft on either side without incon-
venience to the working of the cages or other apparatus, but where gas is not
suspected the instrument without tank is most convenient. Wires or ropes not in
motion can be simply connected with the earth, but in some cases it might be found
advisable to adopt the method above described.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Thomas Canning and William Edgar Thomas in the Great Seal
Patent Office on the 3rd May 1881.
THOMAS CANNING and WILLIAM EDGAR THOMAS, both of Newport, in the County
of Monmouth. " IMPROVEMENTS IN APPARATUS AND MEANS FOR THE PREVENTION
OF EXPLOSIONS IN COAL MINES ARISING FROM ATMOSPHERIC ELECTRICITY."
The first part of this Invention consists in fixing to and above the pit-head
framing of a coal mine a roof, the outer covering of which shall be a material which
is a conductor of electricity.
The second part of the Invention is the attachment of a lightning rod and con-
ductors having a good earth connection, capable, if struck by lightning, to receive
the discharge and conduct it safely into the earth, and also to conduct any discharge
received by the roof in a similar manner to the earth.
The third part of this Invention consists in passing any wire, rope, or rod, in
motion or at rest, or any metallic communication with the mine, through an instru-
ment or apparatus of a very simple character, which will render the wire harmless
in respect to causing any explosion, or giving forth a spark after it has passed
through it. As a spark might pass in the instrument or apparatus itself, an
arrangement by means of pulleys and a water tank is provided, which will effectually
guard against any danger of gas, if any were present, being ignited.
In order that the foregoing may be more easily understood, Drawings are attached
hereto, of which the following is a description:-Fig. 1 is a side elevation of the
pit-head framing and roof; Fig. 2 is a front elevation of the same; Fig. 3 is an
elevation of the apparatus for withdrawing a charge of electricity from the ropes
used in winding or hauling, and as the body of this apparatus is made in two halves,
Fig. 4 is introduced to show one half of the apparatus with its interior parts.
Fig. 5 is a plan of the apparatus not absolutely accurate as to details or scale, but is
inserted in the Drawings to illustrate the manner in which the apparatus is swung
so as to accommodate itself to the motion of the rope passing through it, and one
way in which it may be attached to a wall or other support. Fig. 6 is an apparatus
for the same purpose as Figs. 3, 4, and 5, but is designed specially for use in situa-
tions where the air is strongly impregnated with gas. In Fig. 1 A, A, represents
the pit-head framing braced together with cross and diagonal ties of wood B, B, and
further by wrought iron lattice girders as shown at C. In order to support the
roof brackets D, D, are fixed to the framing, and to these brackets are bolted the
cast iron columns E, E. To the capitals of these columns are cast snugs to receive
the beams of the framing or what may be called the wall plates, as shown at F, F.
These snugs should be of a sufficient depth and width to receive not only the wall
plate but also the insulators hereinafter to be mentioned. To the wall plates is
attached a covering of wood of from one to one and a half inches in thickness, and
this covering extends beyond the wall plates so as to form eaves, as shown at G, G.
Care is taken that that the underside of this covering shall be smooth and offer no
projections or points that can convey an electric discharge to the pit-head
machinery. Between the wall plates and the snugs of the coluinns india rubber of
half an inch more or less in thickness and a wood casing is inserted so as to insulate
the roof from the framing. The outer covering H of the roof is made of wrought
iron or other suitable metal plates or sheets, either plain or corrugated, the said
sheets or plates being fastened to the couples of roof or rafters by stout strips of
sheet brass, which are firmly rivetted at each end to the metal plates and pass
round the wood of the rafter or couple being slightly countersunk in the wood.
This is done to prevent the danger of a lightning discharge following the line of a
bolt or screw if that mode of fixing were adopted.
Stout copper points from eighteen to twenty four inches in length are fixed in
the positions indicated at I, I, and are connected to copper lightning conducting

page_text: rods or ropes J, J, of about five eighths of an inch in diameter running along the
ridge of the roof and round the eaves, being attached to the roof by brass strips K, K,
and connected together with the conductors L leading to earth. The conductors
leading to earth should be copper wire ropes of three quarters of an inch in
diameter or other conductor of equal or superior calibre, and of any suitable make
and form. They are carried down in wrought iron tubes, which latter are supported
by any good conductor of electricity in connection with the pit-head framing, but
always below the brackets D. These supports are shown at M, M, as of wrought
iron rod, and may be increased in number if requisite. The conductors L should
not be less than two in number, and may be more, and should each at its lower end
be fixed to a copper plate N, to which a number of strands of copper rope O should
be attached and run like so many fibres into the earth, which should be good earth,
that is to say, such in which any electric discharge will be at once neutralized, the
clay bed of a deep river or stream that is never dry, in a pond with clay bed, in a
bed of damp clay, or in an iron water main, all being suitable. It is important to
observe that in connecting the points to the conductors or in joining the conductors
together where necessary the greatest care should be taken that a perfect union of
the metals should be secured either by uniting the strands of the rope or by the use
of brass clips or soldering, or by a combination of these or any other suitable method.
A lightning rod is shown at P.
It is also important to mention that wherever an attachment between any part
of the outside covering of the roof or of the conductors is made to the pit-head
framing above the brackets D as perfect an insulation as can be made should be
effected between the two, and that where bolts or pins are used the hole through
which tho bolt or pin passes should be lined with india rubber moulded to the form
and size of the hole. For this purpose the best india rubber of from one quarter to
three eighths of an inch thick should alone be used. The bolts for fastening the
couples to the framing are pushed up from the under side of the beam, the head
being downward. This head is countersunk in the under surface of the beam. An
india rubber washer is employed to insulate it, and the whole space cut out to admit
of its insertion into the beam is filled up with gutta percha, melted first and then
put in when it has cooled to a consistency at which it can be applied; the whole
head is thus covered with the insulating material. A space is left between the bolt
and the india rubber insulator, which is filled up with gutta percha melted
sufficiently to admit of being poured in, and an india rubber washer is applied
under the nut. The nut itself is countersunk and treated the same as the bolt
head, thus thoroughly insulating the bolt. Although india rubber and gutta percha
are here spoken of, any other or a combination of any other equally good and
suitable insulating materials may be used.
Figs. 3, 4, and 5 refer to the apparatus for discharging wire ropes not coming
immediately under the roof after they have become charged with electricity. It
consists of a stout circular brass barrel Q, Fig. 3, having square ends R, R, and
hollow trunnions S, S. These trunnions are attached to the hollow arms T, T, seen
in Fig. 5 by joints, such as are shown at U, U, as ball and socket joints. The
instrument or apparatus is formed in two halves fastened together by the bolts and
nuts V, V. Fig. 4 is a view of one half of the apparatus at right angles to that of
Fig. 3, and exhibits its interior. It is furnished with a number of points W which
project far enough to approach very nearly to the rope that passes in the direction
of Y, Y, through its centre without actually touching it, the rope being kept central
by the guide rollers X, X. The rollers should be made of a hard metal that is a
good conductor of electricity, phosphor bronze, for example. From each of the
points a copper wire Z, Z, proceeds to the interior of the hollow trunnions S, S,
where they are twisted or otherwise united and pass through the hollow arms T,
Fig. 5, and from thence to the earth. It is manifest that any rope which has
received a charge of electricity will in its passage through the apparatus be
discharged, the electric current being drawn off by the points and wheels, and
conveyed through the conducting wires or other conductor to the earth. This

page_text: instrument is designed to be fixed where there is little danger of gas being present,
as owing to the points a spark or sparks may pass in the interior of it. For
instance, it is well adapted for passing the winding ropes through, and for that
purpose may be fixed at or near the spot marked a, Fig. 1.
In case the instrument shown in Figs. 3 and 4 should be placed near a winding
drum, for which there will probably be no necessity, it can be fixed in a sort of
cradle and made to run on guides in order to accompany the motion of the rope
backwards and forwards.
The instrument or apparatus suitable for passing ropes through in any place
where danger is apprehended from the presence of gas, should take the form of a
tank, as shown in Fig. 6. The tank may be of the dimensions indicated, or any
other that may be found suitable, and should be supplied by some automatic
arrangement for keeping it constantly full of water, so that sparks on passing from
the rope to any of the points b will cause no explosion, but pass off by them to a
conductor in connection with the apparatus, and from thence to a good earth.
When the rope is horizontal it may run over the pulleys c, d, e, in the direction of
the line ff, and when vertical, from f to g. In the case of hauling ropes on lovel
roads, or inclines, the tank is embedded in the earth and bolted down to a bed plate
of iron or stone. When in a shaft for an overground hauling rope, it is bedded
firmly to one wall of the shaft, the bed plate extending beyond the face of the wall
ath, bracket like; but for horizontal ropes the bed plate extends out as far
as i.
It will be readily perceived from the foregoing that the roof with its attendant
points and conductors, constructed and arranged as described, will receive and
conduct away harmlessly any lightning discharge however forked. It will effectually
prevent the pulleys and ropes immediately under it being struck by lightning, and
in conjunction with apparatus shown in Figs. 3, 4, 5, and 0, will remove one of the
most dangerous causes of explosions in coal mines, namely, atmospheric electricity
passing by metallic communications with pit-head into the mine. It also obviates
dangers arising from induction.
In each of the Figs. similar letters refer to the same parts of the apparatus.
Having now described and particularly set forth the nature of this Invention,
and the manner in which the same is or may be used or carried into effect, we
would observe in conclusion, that we do not confine or restrict ourselves to the
precise details or arrangements that we have described or referred to, as variations
may be made therefrom without deviating from the principles or main features of
this Invention, but what we consider to be novel and original, and therefore claim as
the Invention secured to us by the hereinbefore in part recited Letters Patent is,-
Firstly. The construction of colliery pit-bead roofs with the conductors, as herein
described and shown on the Drawings.
Secondly. The method of or arrangement for insulating the roof from the pit-
head framing, as herein described and shown on the Drawings.
Thirdly. The construction and application of the instrument or apparatus,
herein described and shown on the Drawings at Figs. 3, 4, and 5, and
Fourthly. The construction and application of the instrument or apparatus
herein described and shown on the Drawings as Fig. 6.
In witness whereof, we, the said Thomas Canning and William Edgar
Thomas, bave hereunto set our hands and seals, this Twenty ninth day of
April, in the year of our Lord One thousand eight hundred and eighty one.