Year: 1887

page_text: Date of Application, 26th Jan., 1887
Complete Left, 26th Oct., 1887
Complete Accepted, 29th Nov., 1887
I, CHARLES AMBROSE MCEVOY of The London Ordnance Works, Bear Lane,
Southwark, in the County of Surrey, Engineer, do hereby declare the nature of this
invention to be as follows:-
This invention hasf or its object apparatus for testing and firing submarine and other
mines.
When the mines are of the class known as "ground mines" and are inactive until
fired by an electric current transmitted from the shore I make the following
arrangements :-
I connect a group of mines by conducting wires with a box which I call a junction
box. This box may be in any convenient position in the immediate neighbourhood of
the group of ground mines. I connect this junction box with the shore by a cable in
which are two insulated wires. On shore these wires are coupled with an instrument
provided with finger keys a step by step indicator and other parts as hereinafter
described. In the junction box also I provide a step by step instrument. These
instruments are worked in a circuit which is completed through one of the wires of tn
cable with return by earth; each instrument has an electro magnet and a propelment
which rotates an axis. The instruments work in unison and each makes a step when
the circuit, which includes a battery, is closed by depressing one of the finger keys in
the shore instrument. The axis of the instrument in the junction box has a cam-like
arm upon it which, as the axis rotates, comes successively in contact with a series of
spring plungers connected with the various mines of which the group is composed.
Each mine is separately coupled with one of the plungers and in addition, the entire
group of mines is again coupled to one plunger.
The second wire in the connected cable is the testing and firing wire; this is
connected at one end with the shore instrument, and at the other end with the cam-
like arm of the step by step instrument. From the arm this circuit passes to the
plunger against which the arm rests and onto one of the mines of the group, from this
mine the return is by earth to the shore instrument.

page_text: The shore instrument contains a testing key and a firing key and also a testing
galvanometer. When the testing key is depressed a current of insufficient strength
to fire the mine passes; this causes a deflection of the galvanometer showing that the
mine then in circuit is in proper working order. By working the step by step instru-
ments, as already described, each mine in succession can be brought into circuit and
tested. In the same way all the mines can simultaneously be brought into circuit,
and then a much larger deflection of the testing galvanometer will be obtained in
consequence of the smaller resistance which the circuit will offer. This indication
serves to show whether the instruments are working in unison if not they can be at once
set to do so. When the firing key is depressed a current passes in the same
external circuit but not through the coils of the testing galvanometer. This current
being of greater strength, brings into operation an instrument in the junction box to
which I have not previously referred. I call this instrument a "disconnector." There
is a separate disconnector for each mine, and when the mine is coupled the testing and
firing circuit passes through it.
The disconnector consists of an electro magnet with an armature controlled by a
spring, so that the testing current does not suffice to draw the armature up to the pole
of the magnet. The armature presses against a spring stud and makes electric contact
with it. The testing current passes through the coils of the electro magnet, through
the armature and by the spring stud to a metal plate connected with the wire
leading to the mine. When the strong firing current is sent the armature is attracted
and it pushes down the stud into contact with a spring; the coils of the electro magnet
are thus short circuited and the firing current passes on to the fuze of the mine without
encountering the resistance which the coils of the magnet oppose to the testing current.
The mine is thus fired. In order that after firing a mine its connecting wire may be
kept out of circuit I make the following arrangement :-I provide a spring catch which,
when the armature depresses the stud upon which it bears, drops in over a shoulder on
the stud; this catch is so arranged that when the armature again leaves the magnet
the stud returns sufficiently far to break the short circuit, but not so far as again to
make electric contact with the armature itself and so to close the main circuit. This
circuit then can never be again closed and on testing from the shore it will be found
to be open which will be an indication that the mine has been fired should this fact not
be already known. The apparatus remains intact for the purpose of coupling other
mines of the group either each in succession or all simultaneously as may be
required.
Where the mines are of the sort known as floating mines and so arranged that
when struck by a floating vessel they give an indication on shore, the arrangements
which I make are as follows:-
I have as before à cable containing two wires connecting a group of mines with the
shore. By the arrangements already described I can bring any mine of the group
into circuit with the shore instrument. The floating mine contains a coil of high
resistance and mechanism so arranged that when a vessel collides with the mine it
causes the resistance to be momentarily taken out of circuit. The testing battery in
this coil is always in circuit with the mine and the current in the circuit is increased
as soon as the resistance is lessened. This increased current causes an electro magnet
in the shore instrument to attract its armature and drop a shutter or part, previously
retained. This in falling may automatically close the firing circuit, and in that case the
mine is instantaneously fired, or if this is not desired the firing circuit can be kept
open by means of a key provided for the purpose.
The shutter also in falling closes a bell circuit and so gives an order indication
that the mine has been struck. A testing key is provided, as in the instrument
previously described, but in this case the testing-key does not open the testing circuit
but simply places the coils of the galvanometer in circuit or removes them when the
instrument is not required.
Sometimes I dispense with the coupling box and employ a cable containing a separate
wire for cach mine.
in the shore instrument I provide a testing galvanometer and a series of finger

page_text: keys one for each mine. I have also a testing battery and a firing battery. One pole
of each battery is connected to earth. The other pole of the testing battery can by the
insertion of a peg be connected with the testing galvanometer and through this to a
lead on which are a series of contacts one to each finger key. When a key is
depressed the current passes by the key to the corresponding wire of the cable thence
to the mine and through the firing apparatus of the mine to earth. The testing
battery when a key is depressed causes a deflection of the galvanometer needle (if all
be in order) but its power is insufficient to fire the mine. By inserting another peg the
firing battery can be coupled with the lead on which are the key contacts and then
when any key is put down the corresponding mine is fired. Or by means of an
additional key all the mines can be fired simultaneously. A number of contact springs
arranged one over the other are connected each with one of the cable wires and the key
when depressed brings all these springs together and also against a contact piece
coupled with the firing battery.
D

page_text: This invention has for its object apparatus for testing and firing submarine and
other mines.
When the mines are of the class known as "ground mines" and are inactive
until fired by an electric current transmitted from the shore I make the following
arrangements :-
I connect a group of mines by conducting wires with a box which I call a junction
box. This box may be in any convenient position in the immediate neighbourhood of
the group of ground mines. I connect this junction box with the shore by a cable in
which are two insulated wires. On shore these wires are coupled with an instrument
provided with finger keys a step by step indicator and other parts as hereinafter
described. In the junction box also I provide a step by step instrument. These
instruments are worked in a circuit which is completed through one of the wires of the
cable with return by earth; each instrument has an electro magnet and a propelment
which rotates an axis. The instruments work in unison and each makes a step when
the circuit, which includes a battery, is closed by depressing one of the finger keys in
the shore instrument. The axis of the instrument in the junction box has a cam-like
arm upon it which, as the axis rotates, comes successively in contact with a series of
spring contact plungers connected with the various mines of which the group is
composed. Each mine is separately coupled with one of the plungers and in addition,
the entire group of mines is again coupled to one plunger.
The second wire in the connected cable is the testing and firing wire; this is con-
nected at one end with the shore instrument, and at the other end with the cam-like
arm of the step by step instrument. From the arm this circuit passes to the plunger
against which the arm rests and onto one of the mines of the group, from this mine
the return is by earth to the shore instrument.
The shore instrument contains a testing key and a firing key and also a testing
galvanometer. When the testing key is depressed a current of insufficient strength
to fire the mine passes; this causes a deflection of the galvanometer showing that the
mine then in circuit is in proper working order. By working the step by step
instruments as already described, each mine in succession can be brought into
circuit and tested. In the same way all the mines can simultaneously be brought into

page_text: circuit, and then a much larger deflection of the testing galvanometer will be obtained
in consequence of the sinaller resistance which the circuit will offer. This indication
serves to show whether the instruments are working in unison if not they can be at once
set to do so. When the firing key is depressed a current passes in the same external
circuit but not through the coils of the testing galvanometer. This current being of
greater strength, brings into operation an instrument in the junction box to which I
have not previously referred. I call this instrument a "disconnector." There is a
separate disconnector for each mine, and when the mine is coupled the testing and
firing circuit passes through it.
The disconnector consists of an electro magnet with an armature controlled by a
spring, so that the testing current does not suffice to draw the armature up to the pole
of the magnet. The armature presses against a spring stud and makes electric contact
with it. The testing current passes through the coils of the electro magnet, through
the armature and by the spring stud to a metal plate connected with the wire leading
to the mine. When the strong firing current is sent the armature is attracted and it
pushes down the stud into contact with a spring; the coils of the electro magnet are
thus short circuited and the firing current passes on to the fuze of the mine without
encountering the resistance which the coils of the magnet oppose to the testing current.
The mine is thus fired. In order that after firing a mine its connecting wire may be
kept out of circuit I make the following arrangement :-I provide a spring catch
which, when the armature depresses the stud upon which it bears, drops in over
a shoulder on the stud; this catch is so arranged that when the armature again leaves
the magnet the stud returns sufficiently far to break the short circuit, but not so far as
again to make electric contact with the armature itself and so to close the main circuit.
This circuit then can never be again closed and on testing from the shore it will be
found to be open which will be an indication that the mine has been fired should this
fact not be already known. The apparatus remains intact for the purpose of coupling
other mines of the group either each in succession or all simultaneously as may be
required.
Where the mines are of the sort known as floating mines and so arranged that
when struck by a floating vessel they give an indication on shore, the arrangements
which I make are as follows:-
I have as before a cable containing two wires connecting a group of mines with the
shore. By the arrangements already described I can bring any mine of the group
into circuit with the shore instrument. The floating mine contains a coil of high
resistance and mechanism so arranged that when a vessel collides with the mine it
causes the resistance to be momentarily taken out of circuit. The testing battery in
this coil is always in circuit with the mine and the current in the circuit is increased
as soon as the resistance is lessened. This increased current causes an electro magnet
in the shore instrument to attract its armature and drop a shutter or part previously
retained. This in falling may automatically close the firing circuit, and in that case
the mine is instantaneously fired, or if this is not desired the firing circuit can be kept
open by means of a key provided for the purpose.
The shutter also in falling closes a bell circuit and so gives an order indication that
the mine has been struck. A testing key is provided, as in the instrument previously
described, but in this case the testing-key does not open the testing circuit but simply
places the coils of the galvanometer in circuit or removes them when the instrument is
not required.
Sometimes I dispense with the coupling box and employ a cable containing a separate '
wire for each mine.
In the shore instrument I provide a testing galvanometer and a series of finger keys
one for each mine. I have also a testing battery and a firing battery. One pole of
each battery is connected to earth. The other pole of the testing battery can by the
insertion of a peg be connected with the testing galvanometer and through this to a
lead on which are a series of contacts one to each finger key. When a key is depressed
the current passes by the key to the corresponding wire of the cable thence to the mine

page_text: and through the firing apparatus of the mine to earth. The testing battery when a
key is depressed causes a deflection of the galvanometer needle (if all be in order) but
its power is insufficient to fire the mine. By inserting another peg the firing battery
can be coupled with the lead on which are the key contacts and then when any key is
put down the corresponding mine is fired. Or by means of an additional key all the
imines can be fired simultaneously. A number of contact springs arranged one over
the other are connected each with one of the cable wires and the key when depressed
brings all these springs together and also against a contact piece coupled with the
firing battery.
The drawings annexed shew apparatus arranged as above described.
Figure 1 is a diagram plan view of a junction box.
Figure 2 a diagram plan view of the apparatus at the shore end, and
Figure 3 a perspective view of one of the "disconnectors."
A B are two insulated wires contained in a cable which connects the shore end
apparatus with the junction box. The outer casing of this box may be made in a
similar way to that described in the Specification of a former Patent granted to me
No. 4959 in the year 1878. C is a step by step indicator in the shore apparatus.
Da finger key for completing a circuit through the coils of the electro magnet of the
indicator. E is the battery for working the indicator. F is the axis of the step by
step apparatus in the junction box, G the electro magnet for giving to it a step by step
rotating movement.
When the finger key is depressed a circuit from the battery E is completed through
the coils of both step by step instruments through the wire A-and the axis of each
of the instruments makes a partial rotation. At each movement of the axis F of the
apparatus in the junction box the arm E extending from it is moved from one or other
of the contact pieces I and passes to the next. Six such contact pieces are shewn
with wires passing away from them to six mines. J is an assemblage of six contact
pieces coupled to the wires of the six mines with all of which another longer arm on
the axis can be brought into contact at one point of the revolution of the axis. Each
contact piece I has a wire passing from it to the "disconnector" K and from the
"disconnector" a wire passes to one or other of the mines.
When the arm H is in contact with any one or other of the contact pieces I a current
for testing or firing can be passed to it from the shore end through the wire B of the
cable.
For testing a circuit is completed through it from a testing battery L through
the switch M. the current passing from the battery to the switch and from the switch
through the coils of the galvanometer N.
For firing a circuit is completed from the firing battery O through the switch P
direct to the wire B-the current passes through the wire B to the axis of the step by
step instrument in the junction box to one or other of the contact pieces I and from it
by a wire a to one of the disconnectors (see figure 3) it passes by the wire through
the coil of the electro magnet c and through its armature d to a plunger e which is
below the armature and so through a metallic plate f through which the plunger works
to the wire g-which passes to the mine.
On the passage of the firing current the armature d is drawn down and presses
downwards the plunger e and brings it into contact with the spring / which is in
electrical connection with the wire a-the current then passes direct through the
plunger to the wire g without passing through the coils.
When the armature is drawn downwards by the electro magnet the head of the
plunger is depressed below the end of the spring catch i so soon as the circuit is com-
pleted direct to the wire 9 without passing through the magnet coil the armature is
lifted by its spring away from the magnet-the plunger is also lifted by a small coiled
spring which is around it until it is out of contact with the spring hand until it is
arrested by the spring catch i which prevents it from rising sufficiently to remain in
contact with the armature. When the parts are in this position no circuit can be again
completed through the magnet coil.

page_text: In figure I have also indicated the drop shutter mechanism and circuits
I use in connection with floating mines for enabling an indication to be given
on shore whenever any one or other of the floating mines is struck by a passing
vessel.
The drop shutter mechanism is similar in its construction to the drop shutter
mechanism described in the Specification of a former Patent granted to me No. 2350
in the year 1884-the circuit from the testing battery L is carried through the coil of
the electro magnet R of the shutter mechanism to the testing switch M and when
the handle of this switch is moved over to the left hand side passes direct to the
wire B and so to any one or other of the mines. If the mine is struck by a passing
vessel and a resistance in the mine so put out of circuit in the manner well understood
the freer passage of the current through the coils of the magnet R enables it to attract
its armature S and drop the shutter T. The dropping of the shutter completes as
described in the above mentioned Specification an electrical connection between two
contact pieces U and thereby completes a circuit from a small battery V through an
electrical bell X and rings the bell. At the same time the dropping of the shutter
completes an electrical circuit through two contact pieces W and thereby if the handle
of the firing switch has been moved over to the left completes a circuit from the firing
battery through the mine. Or if the handle of the firing switch has not been moved
over into position to complete the circuit the person in charge of the apparatus can on
the ringing of the bell cause the mine to be fired if it is required that it should
be fired by at once moving the handle of the firing switch into a position to complete
the circuit.
Figure 4 shows a diagram plan view of an apparatus constructed as herein before
described to be used in cases where a separate insulated wire is led from the shore
apparatus to each mine-either as a separate and independent cable or with the several
insulated wires from the shore carried in one cable to a junction box in proximity
to the several mines and then a separate wire from the junction box to each
mine.
In this figure A A are the wires passing to the mines. B B the finger keys
for completing a circuit through any of these wires either from a testing battery C
or firing battery D.
When testing a contact pin is placed between the two contact blocks E-thereby
as indicated by dotted lines coupling one pole of the testing battery-through the
galvanometer with contact pieces below each of the finger keys B and the finger
Keys are themselves in contact as indicated by other dotted lines with the several
wires A so that on the depression of any one or other of the finger keys a
circuit from the testing battery can be completed through any of the several
mines.
When any of the mines may have to be fired the contact pin is removed from
between the contact blocks E and placed between contact blocks H-thereby coupling
one pole of the firing battery D with each of the contact pieces below the several
finger keys whilst the other pole of the battery is connected to earth so that on the
depression of any one or other of the finger keys a current from the firing battery can
be passed to its corresponding mine. Or if it be desired to fire all of the mines
simultaneously this can be effected in the way indicated by the dotted lines by depressing
the finger key K.
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 :-
1. The combination of a step by step indicator at the shore end a step by step
contact maker in the junction box a cable containing two insulated wires connecting
the two one wire for working the step by step contact mechanism in the junction box
the other for passing a testing curent or strong firing current to whichever of the
mines the contact mechanism may have been brought into connection with.

page_text: 2. The disconnector" constructed in such manner that on any one or other of the
mines being fired no current can be passed to the insulated wire which previously led
to such mine.
3. The combination of apparatus substantially as herein before described and
illustrated at Figures 1, 2 and 3 for testing and firing submarine and other mines.
4. A disconnector constructed substantially as herein before described and
illustrated at Figure 3.
«
27
5. The combination of apparatus substantially as herein before described and
illustrated at Figure 4 for testing and firing submarine and other mines.