New or Improved Apparatus for Preventing Blown Out Shots in Blasting and Getting Coal and other Materials, and in Tunnelling, and for Preventing the Ignition of Explosive Gas in Blasting Operations.
Year: 1886

page_text: Date of Application, 7th May, 1886
Complete Left, 1st Feb., 1887.
Complete Accepted, 1st Mar., 1887.
New or Improved Apparatus for Preventing Blown Out Shots in
Blasting and Getting Coal and other Materials, and in Tunnelling,
and for Preventing the Ignition of Explosive Gas in Blasting
Operations.
I HENRY JOHNSON of Trindle Road Dudley in the County of Worcester Mining
Engineer do hereby declare the nature of this Invention to be as follows :—
My invention consists of the method of blasting and getting coal and other
materials and in tunnelling and in apparatus employed for those purposes herein after
described. My said invention is especially suited for the blasting and getting of coal
but is also applicable to the blasting and getting of other materials such for example
as building stone and in blasting rock and earth and in tunnelling.
I will describe my invention in connection with the blasting and getting of coal.
The principal objects of my invention are to prevent blown out shots in blasting to
render the action of the explosive more efficient and to obviate the danger of igniting
the explosive atmosphere of the mine by the escape of flame in the blasting operation.
I make in the coal to be blasted a bore hole of the ordinary kind. I introduce the
blasting powder as usual but instead of filling up the bore hole with loose tamping I
introduce after the powder a solid tamping of the kind hereinafter described. The
powder and tamping occupy the distant part of the bore hole and the remaining part
is filled up by a plug and wedge or wedges the said plug and wedge or wedges filling
or nearly filling all that part of the bore hole not occupied by the powder and tamping.
The plug and wedge which may be made either of hard wood or metal or other hard
material may occupy nearly the whole of the bore hole the front end of the plug that
is the end nearest the mouth of the bore hole being taper on one or on oppostie sides.
Between the tapering part or parts of the plug and the sides of the bore hole a wedge
or wedges are inserted so that when the explosion takes place the pressure on the plug
fixes it tightly in the bore hole by forcing its taper end between the wedge and bore
hole or between the two wedges the greater the pressure on the plug produced by the
A blown out shot
explosion the greater the tightening of the plug in the bore hole.
is consequently impossible.

page_text: Instead of a single wedge or a pair of wedges several such wedges or pairs of
wedges may be employed the plug being in this case divided in two or more parts and
the parts at the divisions engaging with each other in a manner essentially the same
as that described that is the tapering end of the plug first introduced into the bore
hole engaging in the wedged end of that next introduced and so on.
Instead of using the ordinary loose tamping I employ a solid tamping of such a
nature that while it has sufficient cohesion for transit and handling it is so friable that
on the occurrence of the explosion it is broken up into a fine powder which fills the
interstices between the end of the plug and the bore hole and prevents the escape of
gas. A tamping made of finely divided burned fire clay and plaster of Paris answers
well in practice.
The ignition of the blasting powder is affected through an axial hole in the plug or
plugs and tamping in which hole a metallic fuse is inserted and by means of which
the powder is ignited in the ordinary way or insulated conducting wires may be
inserted in the said hole to fire the powder by electricity. When the plug or plugs
are made of metal they may be utilized in firing by means of electricity.
I employ water in conjunction with the blasting powder for the purpose of prevent-
ing the escape of flame from the exploded powder into the mine. The water may
either be enclosed in a thin metallic or other water tight case of the size and shape of
a charge of powder and be inserted in the bore hole in advance of the powder or the
water may be introduced at the rear of the powder in a hole or series of holes in the
fore end of the plug the end of the plug and the solid tamping being in this case
shaped so that the end of the tamping engages as a stopper in the end of the plug and
retains the water in the plug. On the explosion of the powder the rupture of the
water case or the crumbling of the tamping liberates the water which suppresses flame
and the pressure of any steam which may be formed conspires with the pressure of
the gases liberated by the explosion and assists in the blasting.
The wedging plug or plugs described may be applied to the getting of coal and
minerals where blasting is not employed such for example as the getting of coal and
minerals by the use of quick lime and water.
W. T. WHITEMAN,
Agent for the Applicant.

page_text: Blasting and Getting Coal and other Materials, and in Tunnelling,
and for Preventing the Ignition of Explosive Gas in Blasting
Operations.
I HENRY JOHNSON of Trindle Road Dudley in the County of Worcester Mining
Engineer do hereby declare the nature of my Invention and in what manner the same
is to be performed to be particularly described and ascertained in and by the following
statement:
My invention consists in the method of blasting and getting coal and other
materials and in tunnelling and in apparatus employed for those purposes hereinaftes
described. My said invention is especially suited for the blasting and getting of coal
but is also applicable to the blasting and getting of other materials such for example
as building stone and in blasting rock and earth and iron and other metallic substances
and in tunnelling.
I will describe my invention in connection with the blasting and getting of coal.
The principal objects of my invention are to prevent blown out shots in blasting to
render the action of the explosive more efficient and to obviate the danger of igniting
the explosive atmosphere of the mine by the escape of flame in the blasting operation.
I make in the coal to be blasted a bore hole of the ordinary kind. I introduce the
blasting powder or compound as usual but instead of filling up the bore hole with
the customary loose tamping I introduce after the powder a solid tamping of the kind
herein after described. The powder and tamping occupy the distant part of the bore
hole and the remaining part is filled up by a plug or plugs and wedge or wedges the
said plug or plugs and wedge or wedges filling or nearly filling all that part of the
bore hole not occupied by the powder and tamping. The plug and wedge which may
be made either of hard wood or metal or other hard material may occupy nearly
the whole of the bore hole the front end of the plug that is the end nearest the mouth
of the bore hole being taper on one or on opposite sides. Between the tapering part
or parts of the plug and the sides of the bore hole a wedge or wedges are inserted so
that when the explosion takes place the pressure on the plug fixes it tightly in the bore
hole by forcing its taper end between the wedge and bore hole or between the two
wedges the greater the pressure on the plug produced by the explosion the greater
A blown out shot is consequently
the tightening of the plug in the bore hole."
impossible.
Instead of a single wedge or a pair of wedges several such wedges or pairs of wedges
may be employed the plug being in this case divided in two or more parts and the
parts at the divisions engaging with each other in a manner essentially the same as
that described that is the tapering end of the plug first introduced into the bore hole
engaging in the wedged end of that next introduced and so on.
Instead of using the ordinary loose tamping I employ a solid tamping of such a

page_text: nature that while it has sufficient cohesion for transit and handling it is so friable that
on the occurrence of the explosion it is broken up into a fine powder which fills the
interstices between the end of the plug and the bore hole and prevents the escape of
gas. A tamping made of finely divided burned fire clay and plaster of Plaster or of
compressed unburnt fire clay answers well in practice.
The ignition of the blasting powder is effected through an axial hole or groove in
the plug or plugs and tamping in which hole or groove a fuse is inserted and by
means of which the powder is ignited in the ordinary way or insulated conducting
wires may be inserted in the said hole or groove to fire the powder by electricity.
When the plug or plugs are made of metal they may be utilised as conductors in
firing by means of electricity.
I employ water in conjunction with the blasting powder or compound for the
purpose of preventing the escape of flame from the exploded powder into the mine.
The water may either be enclosed in a thin metallic or other water tight case of the
size and shape of a cartridge of powder and be inserted in the bore hole in advance
of the powder or the water may be introduced at the rear of the powder in a hole or
series of holes in the fore end of the plug the water being retained by means of a
stopping of clay or other material. On the explosion of the powder the rupture of
the water case or the crumbling of the stopping liberates the water which suppresses
flame and the pressure of any steam which may be formed conspires with the pressure
of the gases liberated by the explosion and assists in the blasting.
The wedging plug or plugs described may be applied to the getting of coal and
minerals where a blasting compound is not employed such for example as the getting
of coal and minerals by the use of quick lime and water.
I have represented in the accompanying Drawing the several ways in which I
prefer to carry my invention into effect the several figures representing longitudinal
vertical sections of a bore hole in the coal stone rock or material to be blasted. In
the several figures the gunpowder or other explosive compound is marked a the
tamping is marked b and the wedges e and c².
C
In Figure 1 the explosive powder a is placed at the extreme end of the bore hole
and the tamping & in front of the said powder. The wedge shaped plug c is next
introduced into the bore hole and above and below it the side wedges e². In the said
Figure 1 I have represented three of the said wedge shaped plugs e with their side
wedges but only one of the said plugs with its side wedges may be employed two or
more of the said plugs and side wedges being employed where it may be found
necessary or desirable. I have not thought it necessary to represent in detail the
arrangements by which the explosive compound is fired by a fuse or by electricity as
they are well understood by persons engaged in mining operations. I have however
indicated in the several figures of the Drawing the positions of the holes and grooves
for fuses or electric conducting wires. When the powder a is ignited the liberated
gaseous matter presses upon and crushes the tamping b. the latter presses upon the
broad end of the plug e in contact with it the plug is forced towards the mouth of the
bore hole wedging between the side wedges ². By an examination of Figure 1 it
will be understood that when more than one plug e is used the rear end of the plug
first introduced into the bore hole will on the occurrence of the explosion press upon
the front end of the plug e next introduced causing it to wedge between its side
wedges the second plug will press upon the third causing it to wedge between its
side wedges and so on. The central holes are intended for receiving the electric
wires the holes and grooves above them being intended for a fuse. Only one of these
two methods of conveying the means of ignition is employed in the same plug.
In Figure 2 I have represented an arrangement essentially the same as that
represented in Figure 1 but in the said Figure 2 I have represented a water
cartridge & in addition to the powder a tamping & plug e and wedges the said
water cartridge d being placed in the bore hole in advance of the powder a. I have
also represented in the said Figure 2 an arrangement of the wedging appliances
somewhat different from the arrangement represented in Figure 1. I believe the
differences referred to will be readily understood by an examination of the Drawing.

page_text: In Figure 3 I have represented an arrangement in which the water is situated at
the rear of the blasting compound. In this case the water is contained in the holes ca
in the plug c.
Instead of the three holes represented one two or other number of
holes may be employed. The cross section of Figure 3 is taken through the line A B
Figure 3.
In Figures 2 and 3 I have represented the plugs e near the mouth of the bore hole
as inclined on one side only each wedging with one side wedge only. In Figure 4 I
have represented each of the plugs e inclined on one side only and wedging with side
wedges e inclined on one side only.
In Figure 5 the wedging is effected near the mouth of the bore hole the pressure
on the tamping & being transferred to the mouth of the bore hole by two plugs having
no wedging action.
Figure 6 represents an arrangement similar to that represented in Figure 5
excepting that the plug at the mouth of the bore hole is inclined on both sides and
acts upon two side wedges.
Instead of employing two or more wedges the point end of one being made to act
on the base of the next a wedge may be employed which besides acting upon and
separating its side pieces may carry at its point a cone or wedge the point or narrow
end of which bears against a solid tamping with which the bore hole is filled
preferably to its mouth these parts being employed in conjunction with the powder
water and tamping herein before described as shown in Figure 7.
In some cases I omit the wedging appliances and use only the powder water and
tamping the tamping in this case being made to fill the whole of the bore hole.
Where only a short tamping is used it may be made in one piece but where a
tamping of a length exceeding twice its diameter is required I prefer to make the
tamping in short lengths and in the form of cartridges with central holes or grooves
Where a tamping occupying the greater part of the bore hole is employed a series of
a dozen or more of the said tamping cartridges may be employed.
Having now particularly described and ascertained the nature of my invention
and the manner in which the same is to be performed I declare that I claim as my
invention of "New or improved apparatus for preventing blown out shots in blasting
and getting coal and other materials and in tunnelling and for preventing the ignition
of explosive gas in blasting operations,"
First The employment of a series of plugs and wedges of the several kinds herein
before described and represented in the accompanying Drawing by the use of which
the bore hole is securely closed on the explosion of the powder and blown out shots
prevented.
Secondly-The employment of a specially prepared solid tamping made of a friable
material which tamping is broken up and made to effectually fill the bore hole on the
occurrence of the explosion whether the said tamping be employed in conjunction
with the wedging appliances referred to in the preceding claim or apart from the said
appliances.
Thirdly The employment of water either in a light metallic or other case which
will break on the occurrence of the explosion or in a hole or holes in the part of the
plug bearing against the tamping for the purpose of preventing the escape of flame
from the exploded powder into the mine.
W. T. WHITEMAN,
Agent for the Applicant.