IMPROVED METHOD OF AND APPARATUS FOR PRODUCING INDUCED ELECTRIC CURRENTS to be as follows:
Year: 1885

page_text: Electric Currents.
I, CHARLES DENTON ABEL, of N° 28 Southampton Buildings, Chancery Lano
in the County of Middlesex, Consulting Engineer and Patent Agent do hereby
declare the nature of my invention for "IMPROVED METHOD OF AND APPARATUS
FOR PRODUCING INDUCED ELECTRIC CURRENTS to be as follows:-
"
When induced electric currents are generated by alternately breaking and closing
the circuit of a primary source of electrical energy the speed of succession of break-
ings and closings is limited by the fact that a certain time is required for the
magnetisation and demagnetisation of the iron cores, and consequently the primary
generator will be utilized half the time only.
According to this invention, the possibility of constantly utilizing the primary
generator is afforded by inserting into the circuit of the said generator, in the
manner known as multiple arc, two primary coils, through which the current is
caused to flow alternately, that is to say, every time the shunt of one primary coil
is broken, the shunt of the other coil is closed at the same moment.
The two primary or inducing coils may be arranged concentrically and act upon
one secondary or induction coil placed between them, or every primary coil may
act upon two induction coils, arranged concentrically inside and outside, or arranged
at both ends of the primary coil. In the first case a full core is placed into the
inner primary coil and a ring shaped one into the outer inducing bobbin, while in
the case of two separate primary coils, each enclosed between two concentric
secondary coils, a full core rests in the inner induction coil and a ring shaped one
between the same and the primary coil; in the inductoria the first secondary
coils of which are placed at both ends of the similarly shaped primary bobbin, the
iron core does not extend beyond the ends of this latter.
The two pairs of secondary coils are so inserted in a common circuit that the
current induced by the breaking of the circuit of one primary coil adds to the
current induced by the closing of the circuit of the other primary coil.
In the inductoria constructed according to this invention, the breaking of one
shunt at the moment of the other's shunt being closed is done either by means of a
rotary shaft or by means of a rocking shaft. The rotary shaft carries a metallic
disc, communicating with one pole of the primary generator, while its circum-
ference, divided into a number of conducting and non-conducting squares of equal
length, is in contact with two metallic blade-springs that represent the ends of the
shunts, containing the primary coils and branched off from the other pole of the
source of the primary current the distance between the springs is equal to (2 n + 1)
times the length of a square. When a rocking shaft is to be used, the oscillating
movement of the same is produced by means of electro-magnets inserted into the

page_text: shunts and having their armatures fixed to lever-arms projecting from the shaft,
which carries a diametrical metal arm with conducting and non-conducting squares
on its ends.
To cause the induced current to flow through the consumption circuit always in
the same direction, the apparatus comprises a commutator acted upon by the rotary
or rocking shaft. This commutator consists of two discs or arins, provided with
conducting and non-conducting squares, like the dise and arm already described,
and in contact with two metallic springs each, of which, one spring per arm or
disc, touches the middle portion of a conducting square and the other, the middle
portion of a non-conducting square, at the same time that the springs of the shunt
breaking and closing arm or disc have just arrived on the borders of squares. Of
the springs having similar positions, one pair is connected to the terminals of the
consumption circuit by means of crossed wires, the other pair by means of wires
not crossing each other.
To prevent the formation of sparks by the extra currents, which appear after the
primary circuit has been broken, each apparatus includes a fourth disc or arm
with two contact springs, destined to close at the moment of or a moment before a
shunt being broken, another shunt through which the extra current is allowed to
flow. The said fourth metallic disc or arm has its connection branched from the
same pole of the generator as the two shunts containing the primary coils and the
two contact springs communicate with the wires which run from the primary coils
to the springs in contact with the disc or arm that breaks and closes the shunts
containing said primary coils.
. When the shunt for the extra current is closed, a moment before the correspond-
ing coil's circuit is broken, the closing of the said shunt causes a current to be
"induced, as this closing is equivalent to a considerable weakening of the primary
current flowing through the inducing coil. This current not being induced at the
same moment as the current generated in the other secondary coil in consequence
of the circuit of the corresponding primary coil being closed, a part only of the
induced current would flow through the consumption circuit and the other part
through the currentless secondary coil. To avoid this, two poles of the same name
of the two secondary coils or pairs of coils are connected with the springs in
contact with the arm or disc breaking and closing the shunts which contain the
primary coils, and this arm or disc is connected with one of the arms or discs of
the commutator, while the other arm or disc of this latter is in direct communi-
cation with the two other poles of the secondary coils as usual.
To the same end, viz. for putting out of the circuit the currentless secondary
coil, the following arrangement is used in small duplex-inductoria for therapeutic
purposes and the like, which have no commutator: One pole of the primary
current generator is in conducting connection with the fixed end of a blade spring
carrying the armature of an electro-magnet, which is inserted into one of the two
shunts issuing from the other pole of the generator and containing the two primary
coils; these shunts terminate by contact pieces placed on either side of the blade
spring. The consumption circuit has one terminal connected to two poles of the
same name of the secondary coils, while the other terminal of this circuit is formed
on the fixed end of the blade spring, the forked end of which is placed between
contact-pieces in communication with the two other poles of the secondary coils.
The four contact-pieces are so adjusted by means of their adjusting screws that the
swinging blade spring always makes contact first by its forked end with the con-
tact pieces of the circuits of the secondary coils and afterwards with the contact
pieces of the circuits of the primary coils.
ABEL & IMRAY,
Agents for the Applicant.

page_text: Improved Method of and Apparatus for Producing Induced
Electric Currents.
:
I, CHARLES DENTON ABEL, of N°. 28 Southampton Buildings, Chancery Lane
in the County of Middlesex,. Consulting Engineer and Patent Agent, do hereby,
declare the nature of this invention and in what manner the same is to be
performed to be particularly described and ascertained in and by the following
statement:-
As is known, a certain time, very short it is true, yet measurable, elapses after
the primary circuit of an inductorium has been broken or closed, until the iron
core is wholly demagnetised or magnetised. In consequence of this fact, the speed
of succession of breakings and closings of the primary circuit is limited. Considering
now that during the time from a breaking of the primary circuit till the following
closing of the same, the primary generator is out of use, it will be evident that the
said generator is utilised during half the time only.
According to this invention, possibility for constantly utilising the primary
generator and for doubling the number of current impulsions induced in the
secondary circuit is afforded by the simultaneous use of two inducing coils through
which the current is caused to flow alternately, that is to say, every time the
shunt of one primary coil is broken, the shunt of the other coil is closed at the
same moment.
The two primary or inducing coils may be arranged concentrically and act upon
one secondary or induction coil placed between them, or every primary coil may
act upon two induction coils arranged concentrically inside and outside, or arranged
at both ends of the primary coil.
暑
When the circuit of one of the two primary coils is broken at the same moment
that the circuit of the other coil is closed, and when both primary coils and both
induction coils are of identical construction, the actions of the extra and tertiary
currents will compensate each other.
+
In the apparatus in which there are two induction coils for each inducing coil,
all induction coils are so connected with one another as to cause the current,
induced in one pair of secondary coils in consequence of the circuit of the corre-
sponding primary coil having been closed, to add to the current induced in the
other pair of inducing coils by the breaking of their primary coil's circuit; an
apparatus arranged in this manner will always produce current impulses of the
same strength.
Moreover, in apparatus of this kind, each coil may be composed of several sections,
and then identically constructed sections of different coils may be connected in
groups which, in consequence of the compensation of the tertiary currents, are
quite independent of each other.
To the purpose of alternately breaking the circuit of one primary coil at the
same moment as the circuit of the other is broken, a continuously, revolving shaft
may be provided, the said shaft carrying a metal disc, which is connected to one

page_text: pole of the primary generator and has its cylindrical circumference divided into a
number of conducting and, non-conducting squares of equal length, and two
metallic blade springs, which represent the terminals of shunts, branched off from
the other pole of the generator and containing the primary coils, being in contact
with the said cylindrical circumference.
Especially in smaller apparatus, the, revolving shaft is with advantage replaced
by a rocking one, the oscillations of which are produced by means of two lever-
arms, extending in opposite directions and carrying the armatures of electro-
magnets interposed in the shunts which contain the primary coils; one of these
electro-magnets may be replaced by a spring, in which case a suitable resistance
must be included in the shunt containing no electro magnet. The disc of the
revolving shaft is replaced by a metallic arm, arranged crosswise of the shaft and
extending to either side, the said arm communicating with one pole of the
generator and presenting at. its end faces an upper conducting square and a
lower non conducting square or inversely; these end faces are in contact with
metal springs, representing the terminals of the shunts within which the primary
coils are interposed.
•
In order to prevent the formation of sparks by the extra-currents which appear
on the breaking of the primary circuit, another shunt is provided beside cach of
the shunts containing the primary coils, this other shunt being closed for a short
time at the moment when the circuit of the corresponding primary coil is broken.
For utilising the extra current and slowing its course, a primary coil surrounded
by an induction-coil may be included in the said shunt. Both extra-current
shunts are closed and broken in the apparatus comprising a revolving shaft by
means of a disc having conducting and non-conducting squares on its circumference,
and in the apparatus provided with a rocking shaft by means of a transverse arm
having conducting and non-conducting squares on both end faces.
A further characteristic feature of the apparatus lies in its commutator, the
construction of which is conforined to the briefly described general arrangement of
the inductorium, and which is actuated by the existing revolving or rocking shaft.
According to the special purpose of the apparatus, all current impulses induced by
the two primary coils may be transformed into a continuous current by means of
one and the same commutator, or several commutators may be provided. The
commutator consists of two discs or arms, insulated from each other and from the
shaft, one disc or arm being electrically connected to one terminal of the circuit
containing the induction coils, and the other disc or arm to the other terminal of
this circuit. Each disc or arm is in contact with two metal springs, and while
one pair of springs touches the middle of the conducting squares; the other pair
touches the middle of the non-conducting squares, these positions of these springs
coinciding with the passage of the springs in contact with the make and break
disc or arm from a conducting to a non-conducting square. Of the electrical
connections establishing communication between the said pairs of contact springs
and the terminals of the working circuit, two cross each other, while the two others
do not do so, this arrangement having for its effect that equal direction is given
to all current impulses.
When the described principle of double induction is to be employed to small
inductoria as used for producing sparks, or for therapeutic purposes and the like,
the alternate breaking and closing of the shunts containing the primary coils is
obtained by means of two contact-pieces arranged on either side of a plate-spring
carrying the armature of an electro magnet. The free end of the said spring is
forked and to each branch of the fork answers a contact piece connected to one of
the two induction coils.
In the annexed drawings, Figs. 1, 2 and 3 shew different arrangements of the
'two primary coils and the corresponding induction coils.
Figs. 4a and 4b are diagrams of the coincidence and succession of breakings
and closings of the circuits of both primary coils and of the extra current shunts.

page_text: Fig. 5 is a diagram shewing the general arrangement of an apparatus provided
with a revolving shaft, and timed for the closing of the extra current shunts a
moment before the circuits of the primary coils are broken. Fig. 6 shews the
arrangement of an apparatus, having a rocking shaft and being timed for the
closing of the extra current shunts at the same moment as the primary circuits
are broken. Figs. 7 and 8 shew details of these apparatus. Fig. 9 is a diagram
of a small duplex inductorium for the production of sparks. In Fig. 1 two
concentrically arranged primary coils a and a' act alternately upon an induction-
coil b placed between them. The inner primary coil a as well as the outer one a¹
is provided with an iron core c and c¹ respectively. The full inner core o may be
formed, as usual in induction apparatus, of thin iron rods insulated from each
other, while the outer core c¹ of ring shaped section is made of spirally wound
sheet-iron.
With the arrangement shewn by Fig. 2, the primary coils a a¹ are separated
from each other and each coil acts inward and outward upon concentric induction
coils, band b¹ respectively. In this case, the inner induction coil 6' incloses a full
iron core c, and the primary coil a core c¹ of ring-shaped section, which may also
be made by rolling sheet-iron.
Fig. 3 shews two inducing or primary coils, a and a², arranged side by side and
being more or less disc-shaped, that is to say of comparatively large diameter and
small height, these coils acting by both plane surfaces upon similarly shaped
induction-coils, b and 6. The primary coil contains an iron core c, which does not
extend into the two induction coils b and 6' and, moreover, the primary coil is
surrounded by a third induction coil bª..
From the Figs. 4a and 46 it may be seen in what. manner the breakings and
closings of the shunts containing the two primary coils a and a¹ and of the extra-
current shunts must coincide and succeed for producing four induced current
impulses, and at the same time avoiding the formation at the make and break disc
or arm of the sparks of the extra currents of opening, as these sparks soon would
wear off the metallic surfaces. In the said figures, the upper and lower stripes
represent the extra current shunts, corresponding to the primary coil shunts, which
are represented by the two middle stripes; the hatched squares mean spaces of time
during which the circuit is broken, the white squares, spaces during which the circuit
is closed. Obviously, these diagrams enable one to ascertain in what manner the
conducting and non-conducting squares and the contact springs have to be arranged
on the circumferences of the discs D and E, Fig. 5, or on the end faces of the arms
D¹ and E¹, Fig. 6, by which discs or arms the primary coil shunts and extra current
shunts are alternately closed and broken.
The arrangement shewn by Fig. 4a is such as to cause the extra current shunt to
be closed at the moment when the circuit of the corresponding primary coil is opened.
As with this arrangement it may be difficult to exactly adjust the contact springs,
one may, as shewn by Fig. 4b, cause the extra current shunt to be closed a moment
before the circuit of the corresponding primary coil is broken by the contact spring
touching the make and break disc or arm. In this case the extra current shunt
ought to be of low resistance, and for this reason, the primary coil, of which it has
been stated above that it is interposed into the shunt for utilising the extra current,
is dispensed with. As may be seen from Fig. 4b, the current impulses are not
induced at once with this arrangement; therefore it is not possible to connect with
each other the two pairs of induction coils, as is done with the arrangement of the
apparatus shewn by Fig. 4 a. On the contrary it is necessary, when the impulses
induced in both pairs of bobbins shall flow through one and the same circuit,
to put out of the circuit the currentless bobbin ; unless by this excluding of the
currentless coil, a small portion only of the current would flow through the working
circuit or line.
.
The principles upon which the construction of double induction apparatus is
based being fully explained by the above statements, a few words will suffice for

page_text: describing, with reference to Figs. 5 and 6, the apparatus provided with a revolving
shaft and that having a rocking shaft.
In the drawing it is supposed that, in the apparatus having a revolving shaft w
Fig. 5, the conducting and non-conducting squares are arranged according to the
diagram Fig. 4b. The shaft w carries four metal discs D, E, F, G, insulated from
the same and having their circumferences divided into a number (equal in all disca)
of conducting and non-conducting squares; the non-conducting squares are dis-
tinguished by hatchings in the drawing. The disc D by which the two primary
coils a and a¹ are alternately put in and out of circuit, is provided. with conducting
and non-conducting squares of equal length. Upon the nave of the disc there.rubs
a spring & electrically connected to one pole of the primary generator S, while the
circumference of the disc is touched by two springs & and d²; the interval between
these two springs being equal to (2 n + 1) times the length of a square, one of the
springs will be passing from a conducting square to a 'non-conducting one, while
the other spring just passes from a non-conducting square to a conducting one.
These two springs d' and d' represent the terminals of shunts issuing from the
other pole of the primary generator and having the primary coils a and a¹ inter-
posed into them. In the drawing, the circuits of the primary current, which have
just been in question, are represented by full lines.
The disc E serves for opening and closing, according to the diagram 4b, the
extra-current shunts corresponding to the inducing coils a and a¹. These extra-
current shunts, which are indicated by an interrupted line,.consist on the one hand
of a portion of circuit, branched off from the connection between the coils a and a¹
and the generator S, and running to a spring e which touches the nave of the
disc E; on the other hand, these shunts consist of two connections which are
branched off from the communications between the primary coils and the springs
d' and d', and which terminate by springs e¹ and e³ rubbing on the circumference
of the disc E. As, according to the diagram Fig. 4b, the extra current shunts are
always to be closed a moment before the corresponding spring d' or d² passes from
a conducting square to a non-conducting one, there must be on the circumference
of the disc E one conducting square per each second divisional line between the
squares of disc D, and as the extra-current shunts need to be closed during a very.
short time only, the conducting squares of disc E may be made very narrow.
When, for instance, as it is shewn in the drawing, the spring e' touches a con-
ducting square, nearly the whole current arriving through the spring d, instead of
returning from the spring d to the negative pole of the generator S by the way of
the coil a, will follow the communication of less resistance through the spring e¹,
the disc E and the spring e.
.
The communications serving for taking off the current impulses induced by the
bobbins b and b¹, and for transforming the same into a continuous current, are
represented in the drawing by long and short dots. As it is supposed in Fig. 5 of
the drawings that the currents induced in both induction coils shall be conveyed
into one and the same working circuit X Z, and that, according to the diagram
Fig. 4b, the current impulsions of both induction coils do not add to each other
immediately, it is necessary to always put out of circuit the currentless coil, for
preventing the current induced in the other coil from partly flowing through this
coil, instead of entirely flowing through the working circuit. This is done by
means of the disc D, to the contact springs d¹ and d³ of which, those pand p of
the terminals of both induction coils band b₁ are electrically connected to a spring f
touching the nave of a disc F. From the other terminals, p' and 2 of the induc-
tion-coils a common and direct communication is formed to a spring g in contact.
with the nave of a disc G; consequently, the discs F and G may be looked on as
the terminals of the circuit of the alternating current produced by the apparatus..
The circumferences of the discs F and G present conducting and non-conducting
squares of the same length as those of disc D, and in contact with two springs.fi
and the one, gl and g³ the other. Of these four springs, one pair, for instance the

page_text: pair and g, always touch conducting squares, while the other pair f' and g³ touch,
non-conducting squares and while the springs d' and d are just passing from a
conducting to a non-conducting square, or inversely. The springs of one of these
two pairs are connected to the terminals X and Z of the working circuit by means:
of crossed communications, those of the other pair by non-crossed ones, this
arrangement having for its effect that all current impulses arriving at a, given one,
of the terminals ✗ and Z are of the same. direction.
When there are two working circuits, it is not necessary to alternately put out
of circuit one and the other of the two, induction-coils, as in this case the currents;
induced by each coil, b'or b¹, or by cach group. of coils are conveyed to separate;
commutators of the described kind.
..
In the apparatus shewn by Fig. 6, a rocking shaft w' is provided, this shaft being
actuated by two electro-magnets M and M', the armatures of which are fixed to.
both ends of an arm H, rigidly connected to the shaft wl and extending in:
diametrically opposed directions. It is supposed that in this apparatus the
breaking and closing of the circuits of the two primary coils a a¹ and of the extra-
current shunts shall be performed according to the diagram Fig. 4u; and the end
views annexed to the Fig. 6, shewing the end faces of the arms D E F G¹, which
replace the discs of the apparatus Fig. 5, illustrate the arrangement of the con->
ducting and non-conducting squares. In order to admit of the springs and elon.
the one side, and d' and e' on the other side, being exactly adjusted for closing the.:
extra-current shunt at the same moment that the circuit of the primary coll:is
broken, the arms D' and E¹ are arranged near each other and the said pairs of.
springs are made in one piece each.
As in this case the induced current of closing of one secondary coil always adds
to the induced current of breaking of the other secondary coil, there is no current-
less coil to be put out of circuit, and consequently the terminals p and p¹ of both
induction coils are directly connected to the springs f and g, touching the naves of
the commutator arms F1 and G¹:
Figs. 7 and 8 shew a cheap, exact and durable manner of making the discs and
arms, which have been described with reference to Figs. 5 and 6. Each arm or
disc is composed of two symmetrical halves h and h¹ respectively, these balves made
of metal being separated from the shaft w or w³ respectively by means of sleeves i
made of hardened rubber at those points, where non-conducting squares are to be
formed, the said halves are recessed, and finally a piece of serpentine k, having.
identically the same form as the said discs or arms, is inserted between these.
However, as with the use of serpentine considerable friction is met with, and as
therefore the apparatus would be subject to rapid wear, the piece k may to.
advantage be replaced by an arm or disc, made of metal. and insulated from the
halves or h¹ and from the shaft.
For illustrating the manner in which the principle of double induction may be
employed to smaller inductoria, of the kind of those which are used for therapeutic
purposes and the like, the diagram of such an apparatus is shewn by Fig. 9. The.
circuit of the primary current, represented by a continuous line, runs from one pole
of the generator S to the primary coils a and a¹, each interposed in a shunt of the
circuit; one of these shunts contains the coil of an electro magnet M and finally.
terminates by a contact screw n, which is arranged near the back-side of a blade-
spring t, the front-side, of which carries the armature m of the said electro
naguet M, while the other shunt is directly connected to a contact screw n¹.
placed in front of screw n and on the same side of the spring t as the electro-
magnet M. The blade spring t being in communication with the other pole of the
generator S; the shunts of the primary coils a and a' will be alternately closed and
broken under the action of the electro-magnet M. In order to convey into a
common working circuit X Z the current impulses induced in both induction-
coils.b. and 6, the free end of the spring. t is forked into. two branches t¹ and t?,.
each faced by a contact screw T..and respectively, these screws communicating.

page_text: each with one terminal or pole of the same name, p and p, respectively, of the
induction coils b and b²; the other terminals p² p¹ of these coils have a common
connection to one terminal Z of the working circuit, the other terminal X of which
is formed at the fixed end of the blade spring t.. As, with the described arrange--
ment, the breaking of one primary shunt does not coincide with the closing of the
other, it is a matter of importance to keep the circuit of each secondary coil closed
while the corresponding primary coil is once closed and opened; this is obtained
by so adjusting the screws n and on the one hand, and´n' and r¹ on the other
hand, that the swinging spring t always first touches the screw r or 7¹ and after
this only the screw n or n¹, and inversely, that said spring first separates from the
screw n or n¹ and then from the screw r or r¹.
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 herein described method of constantly utilising the primary electrical
generators which serve for the production of induced currents by alternately
breaking and closing their circuits, the said method consisting in the division of
the primary circuit into two shunts each containing an inducing coil surrounded
by an induction coil, and in alternately passing the primary current through one
and the other of these shunts.
2. So arranging primary coils as to act upon induction coils both by their inside
and by their outside or simultaneously by both ends.
3. In an apparatus serving for the induction of continuous currents according to
the method referred to in claim 1, the use of three metal discs D, F, G mounted
upon a revolving shaft and presenting on their cylindrical circumferences con-
ducting and non-conducting squares of equal length throughout; the disc D
destined to break and close the shunts of the inducing coils a and a being
in communication with one pole of the primary generator S and. having its
circumference touched by two metal springs d' d' distant from each other by
(2n+1) times the length of the squares and representing the terminals of said
shunts, while the discs F and G represent the terminals of the circuit of the
induction coils and are touched by springs f¹ ƒ³ and g¹ g² respectively, of which
the pair f¹ gl always rub on conducting squares, while the pair f g³ rub on non-
conducting squares, and while the springs d'and d' are just passing over divisional
lines between two squares; one of the said pairs being connected to the terminals X
and Z of the working-circuit by crossed communications, the other pair by non-
crossed ones.
.
4. In an apparatus of the construction referred to in claim 3, the use in place
of the revolving shaft w of a shaft w', which is oscillated by means of electro-
magnets M M included in the shunts containing the primary coils a a³, and which
carries, instead of the discs D F G, arms D' F¹ G₁ extending in opposite directions
and having their end faces divided into conducting and non-conducting squares.
5. For the purpose of preventing in the apparatus referred to in the claims 3
and 4 the formation of sparks by the extra-current of opening, the use of a disc E
or arm E¹, representing the terminal of a third shunt of the primary circuit, and
having its circumference or ends touched by springs e¹ and e³, the communications
of which are branched off from the two other shunts between the primary coils.
and the springs and d² respectively, and which enter conducting squares at the
moment when, or a moment before the shunt of the corresponding primary coil is
broken.
6. In combination with apparatus of the kind referred to in claims 3, 4 and 5,
and being arranged for the closing of the extra current shunt a moment before the
shunt of the primary coil is broken, the use of an arrangement having for its effect.
to put out of circuit. the currentless induction coil, and consisting in electric
communications between one pole of the same name p of both induc-coils b and b¹

page_text: and the springs d' and d' on the one hand, and between the spring d and the
commutator on the other hand.
7. In the duplex induction shewn at Fig. 9, effecting the alternate opening and
closing of the two shunts containing the primary coils and the transmission of the
induced current impulses, the currentless secondary coil being put out of circuit,
by means of a blade spring t having its free end forked into two branches t¹ t³,
carrying the armature of an electro-magnet, and being placed between the
terminals n and n¹ of the shunts containing the primary coils, and between the
terminals and of the shunts containing the induction coils.
ABEL & IMRAY,
Agents for the Applicant.