Improvements in Electric Telegraph Apparatus.
Year: 1899

page_text: Improvements in Electric Telegraph Apparatus.
SIDNEY GEORGE BROWN Van Buren Poole Rd Bournemouth (in the County of
Hants) Electrical Engineer do hereby declare the nature of this invention to be
as follows:-
1
This invention consists primarily in improvements in telegraphic relays,
whereby the relay is capable of working by minute forces, such as are likely to be
encountered at the ends of long submarine cables, and also. of working with an
absolute assurance of contact, this not always being obtainable with delicate relays
when fixed contacts are employed.
The following is a description of a relay embodying my invention.
The tongue of the relay is fixed, either rigidly, or by means of frictional con-
straint, to the top of a suspended coil of wire, of any convenient, shape and size,
the coil as usual working in a permanent or electro-magnetic field, as in the
"siphon recorder". The current sent to move the relay, passes through the con-
volutions of the suspended coil giving it the necessary notion, which it in turn,
communicates to the tongue connected to it.
The end of the relay tongue bears lightly upon the surface of a rapidly rotating
metallic drum or disc, making in most cases continual metallic contact.
The metallic drum is suitably subdivided, the subdivisions being insulated,
one from the other, by convenient insulating material, such for instance as thin
mica.
It will be seen that if contact brushes bear upon the subdivisions, a current can
be made to flow, through the relay tongue, and round any circuit connected, pro.
vided the end of the relay tongue is moved so as to make contact with the
division.
Adjustable stops may be fixed in any convenient position so as to limit the
notion of the relay tongue, and the relay tongue can be fastened in any way that
would be thought convenient to the moving coil, either rigidly or by adjustable
frictional constraint.
If the relay is constructed for receiving cable signals it might be most con-
veniently fitted with two contact making tongues, one fixed, and one frictionally
constrained, the exterior motion of the fixed tongue, either to right or left, chang-
ing over the connections, for the tongue moved through frictional constraint.
The contacts in this case as before, being made between the ends of the relay
tongue, and metallic drums or discs in rotation, these drums or discs suitably sub-
divided, and coupled to any circuit or circuits, as is thought necessary..

page_text: If the zero of the signals received from the cable, was found not to be constant
in position, the relays could be fitted with auxiliary coils, fixed in parallel with the
working coils, and receiving current from the secondary circuit, this current being
previously sent through suitable contacts, either moving or fixed, and a circuit
having, resistance, induction, or capacity, or any combination of these, reproducing
the same variable effect on the zero, but opposite in direction, and therefore
eliminating this disturbing factor from the working of the relay.
This method of removing the effect of variable zero of the arrival current, on
relay working, could be fitted to any make of relay.
It has been found, that the resistance of contact between the end of the relay
tongue and the revolving drum is not quite constant in amount. especially when
the end of the tongue, bears lightly on the drum, but any variation in strength of
current passing, due to this, can be enormously reduced, by shortcircuiting the
sliding contact, by a condensor of suitable capacity.
It is also reduced by placing resistance and inductivity in the circuit.
In some cases it might be found convenient, to construct the relay, so that the
end of the relay tongue, is normally clear, of the rotating drum, contact being
made by the relay coil moving the end of the tongue, up against the moving
surface.
It must be understood that I do not limit myself to a suspended coil for moving
the relay tongues, but any method now known to the art may be used, but if
extreme sensitiveness was required I might construct the tongue of fine wire, fixed
at one end, the other bearing on the surface of a revolving drum, the operating
current flowing along the wire, the wire being placed in a strong magnetic
field.
Any method of spinning the contact drum or disc, could be employed but in
many cases it would seem most convenient to fix the armature of a small
electromotor directly to the shaft.
It is essential in long land lines, and cable working, especially if relays are used
as receivers, that the instruments, both for transmitting, and receiving should be
constructed so as to give the maximum definition to the signals, and anything
that adds to the definition naturally improves the efficiency, and increases the
speed.
The inventor has found that to get the maximum definition of the signals
received, through any line the transmitting device should be fitted with a curb,
and that the receiving instrument should be short circuited by a coil preferably
having a closed magnetic circuit, and possessing high self induction with but
moderate resistance. Under these conditions, no condensors need be placed in
series with the line, as although they act somewhat in the direction of a curb, they
do not seem to improve definition.
If the cable or line is displaced it would seem better to allow the current to
enter the line at a mid joint in the inductive shunt, flowing equally down each
division, neutralizing by mutual induction the self induction of the entering
current.
The bridge balance being adjusted by a moveable contact maker, so connected
that the position the sending currents enter the inductive shunt can be suitably
altered, a sinall adjustable rheostat being also placed if necessary at the apex of
the bridge.
It would be convenient likewise to place moving contact makers at each end of
the inductive coil so as to alter the number of turns that act for the shunt.
It is important that the inductive shunt should possess little resistance, and for
that reason it should be of the closed magnetic type, but to increase the efficiency
still more I might arrange to give an initial excitation to the iron bringing it, pre-
ferably near its critical point.
To do this I should arrange the iron core with three arms, round one of these I
should wind the exciting coil and as it is essential that no inductive effect should
act on this part of the circuit, by currents moving in the other coils I should

page_text: "
equally wind the other two arms of the iron core in such a manner that the current
in one winding would tend to decrease the inagnetism in the same proportion as
the current in the other arm tends to increase it. These two coils to be coupled in
series for acting self inductively or else the winding may be coupled and disposed
so as to act as a transforiner, when it would be usefull for telegraph, purposes, for
which transformers are now used.
It has been found, when working duplexed cable lines with curb transmitters, as
I have above proposed that additional difficulties of obtaining and maintaining
balance is introduced by the curb.
"
I propose to avoid this by the insertion in the "fork" of the bridge and in series
with the receiving instrument a coil possessing suitable self induction and of small
resistance.
Dated this 17th deve of Januar: 1800
I, SIDNEY GEORGE BROWN, of Van Buren, Poole Road, Bournemouth, in the
County of Hants, 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 :—
This invention relates to improvements in telegraph apparatus whereby the relay
apparatus is capable of being worked efficiently by minute electrical forces such as
are likely to be received at the ends of long submarine cables, and is also capable
of working with an absolute certainty of contact which is not in such cases obtain-
able with delicate relays, when fixed contacts are employed.
My improvements also relate to means for eliminating a varying zero in the
recording instruments and for obtaining a better definition of the signals than
heretofore.
An important feature of my invention is the employment of a relay apparatus
with a tongue or tongues connected to one end of a relay circuit and adapted to be
Inoved by the arrival signalling current so as to make or break circuit with a
moving surface connected to the other end of the relay circuit.
Another feature of my invention consists in short circuiting the receiving
instrument by an inductive coil or magnetic shunt. It is important that these
coils or shunts shall possess high self induction with but moderate resistance and
for this reason I construct thein of induction coils having closed magnetic circuits.
These coils or shunts prevent a varying zero in the receiving instrument by
eliminating slow irregular currents, and thereby increase, or obtain the maximum
definition of the signals, and thus improve the efficiency and augment the speed
of said signals. I may increase the efficiency of such self inductive coil or shunt,
by employing an electric current to initially excite the iron of said coil so as to
bring it to a critical stage and thus render it very sensitive. When using such self
inductive coils it is not necessary to employ the condensers usually placed in series
with the line.
My invention also comprises the use of the closed oircuit in ductive coil or magnetic
shunt, not only for the receiving relay or other receiving instrument but also for
the arms of the "bridge" used in duplex transmission. For this purpose the
ingoing current enters the magnetic shunt at its mid-point so that one half of the

page_text: An
said current neutralizes the inductive effect which would be produced by the other
half of said current, and the shunt therefore behaves as a plain resistance.
adjustable contact maker or rheostat may be placed at the "apex" of the bridge
for adjusting the "bridge balance," whereby the point at which the current enters
the inductive shunt can be suitably altered or adjusted. Adjustable contacts may
also be provided at each end of the inductive coil so that the number of turns of
said coil which constitute the shunt may be altered as required. Also adjustable
external resistances may be included in the bridge arms for facilitating adjustment
and balancing.
To overcome the difficulties of obtaining and maintaining "balance" introduced
when working duplex lines with curb transmitters as aforesaid, I may insert in the
"fork" of the bridge and in series with the receiving instrument a closed circuit
coil possessing suitable self induction and having but moderate resistance, in order
to avoid "jars" on the receiving instrument.
In order that my invention may be clearly understood and readily carried into
effect I will proceed to describe the same more fully with reference to the accom-
panying drawings in which :-
Figure 1 is an end elevation.
Figure 2 is a plan and
-
Figure 3 is a side elevation with one pole of the magnet removed, of relay
apparatus constructed according to my invention.
Figure 4 shows a rotary contact surface or drum divided into five sections
insulated from one another.
Figure 5 is a side elevation and Figure 6 is a plan of a modification of the
apparatus shown in Figures 1, 2 and 3, in which modification both a fixed tongue
and a frictionally controlled tongue are employed.
Figure 7 is a diagrammatic view of a modification of the relay apparatus.
Figures 8 and 9 are diagrammatic side and plan views respectively, of another
modification of the relay apparatus.
Figure 9 is a diagrammatic plan view of a modification of the arrangement shown
in Figures 8 and 9.
Figure 10 is a diagram of a cable circuit in which the receiving instrument is
short circuited by a closed circuit self inductive coil or magnetic shunt.
Figure 11 is a diagram of one end of a duplex cable circuit in which the
receiving instrument is short circuited by a closed circuit self inductive coil or
magnetic shunt.
Figure 12 is a diagram of one end of a duplex cable circuit in which the
receiving instrument is short circuited by a closed circuit self inductive coil or
magnetic shunt, and in which a different arrangement of bridge to that shown in
Figure 10, is employed.
Figure 13 is a similar diagram to that shown in Figure 10, and shows movable
contacts for adjusting both the bridge balance and the number of turns of the coil
constituting the inductive coil or magnetic shunt.
Figure 14 is a diagram of one end of a duplex cable circuit in which curb
transmitters are employed and in which closed circuit inductive coils are placed
in the "forks" of the bridges and in series with the receiving instruments.
Figure 15 shows an inductive coil having a closed inagnetic circuit, suitable for
the
purpose of my invention.
Figure 16 is a cross sectional view of the coil shown in Figure 15.
Figure 17 shows another form of inductive coil having a closed magnetic circuit
and adapted to have its iron core initially excited so as to bring it to a critical
state.
Referring to Figures 1 to 3,
A is a light wire coil delicately suspended in the field of a permanent or electro
magnet a. B is a relay tongue fixed to the top of the coil A. C is a rotary disc
or drum mounted on a spindle C supported from the frame of the instrument by
suitable bearings. This druin C is made in sections separated by insulating

page_text: material c which may be a metal ring of suitable width having its sides covered
with insulating material, or may consist of thin mica insulation. The free end of
the tongue B bears lightly upon the rotary drum C and should be of a width not
exceeding the width of the insulating strip c.
The main line conductors E, E are.
connected to the coil A by very fine wire coils. One end of the relay circuit F is
connected to the sections of the drum C by a divided battery and suitable
brushes, ff, and the other end of the said relay circuit is connected to the tongue B.
G is a recording instrument in the relay circuit. c' is a pulley which is mounted
on the drum spindle C' and which is connected to any suitable source of power for
rotating the drum C. b b are adjustable screw-stops carried by the frame of the
instrument, for limiting the lateral movements of the tongue B. a¹ is a lug
projecting from the bottom of the coil and a² a² are springs having their ends
respectively attached to the lug a¹ and to the frame of the apparatus.
"
The coil A is normally suspended so that its plane is parallel to the north and
south line of the magnet a, in which position the tongue B is in contact with the
insulating strip c, that is to say, the tongue is in its zero position. The arrival.
signalling current from the main line circulating in the coil A, turns this coil out
of the north and south line of the magnet a (to an extent which depends upon the
strength of the said current) and moves the tongue B laterally into contact with
one of the sections of the rotary drum C, thus making contact and enabling a
current to pass through the relay circuit.
The object of rotating the drum C is to reduce the friction between it and the
end of the tongue B to a minimum, so that very minute forces may be enabled to
inove the said tongue as above described.
The rotary drum C may consist of any suitable number of insulated sections,
8Such number of sections depending upon the required properties of the relay. For
instance, (as shown in Figure 4) when it is required to adapt the instrument for
receiving signals over lines where the signals are likely to possess what is known as
a varying zero", such as would be caused by the charging up action of a receiving
condenser, the drum C may be divided into five sections, c, c², c³, c, c5, insulated
from one another by suitable material. c is the central insulation ring or piece
forming the mechanical zero of the instrument as previously described. When the
tongue B moves into contact with either of the divisions or sections c² or ct, a signal
is indicated as previously described. If the tongue B is caused by the arrival
current to move too much to one or other side owing to the said varying zero, the
said tongue makes contact with one or other of the sections c³ or cs (which may be
termed correcting sections). These sections c³ and care so arranged that when
they are thus in contact with the said tongue, not only does the signal continue to
be indicated in the same manner as if the tongue were resting on section c² or c¹,
but an auxiliary relay is also worked; this auxiliary relay works in conjunction
with the main relay and causes a correcting current to be sent through a few
auxiliary turns of wire wound on the coil A, in such a direction as to cause the
tongue B to move back towards the insulating strip or piece e to such an extent as
to make the electrical zero as far as possible coincide with the mechanical zero of
the instrument.
:
If the relay circuit is constructed for receiving cable signals, it may in order to
facilitate the reading of the signals (especially with hand sending) be incst con-
veniently fitted with two contact-making tongues, one fixed to and the other
frictionally controlled by the suspended coil, the motion of the fixed tongue either
to right or left changing over the connections for the frictionally controlled
tongue.
Such an arrangement is shown in Figures 5 and 6, in which A is the suspended
coil, B is a tongue rigidly fixed to the said coil and B₁ is a tongue having a hole in
it through which passes a rod a³ fixed to the coil A. The rod as is screw threaded
and carries a screw nut a' at its upper end. The tongue B rests upon a boss of
insulating material a and is there retained by the spring a', one end of which

page_text: bears on the under side of the nut at. The tongue B' is thus frictionally attached
to the coil A.
The tongues B and B at one extremity bear upon the rotary drum C and at the
opposite extremity are connected to one end of the relay circuit F. G, G¹ are
the recording instruments. bbare stops for limiting the lateral movements of
the tongue B and bare stops for limiting the lateral movements of the
Longue B'.
The magnet a and remaining parts of the apparatus are omitted from
these figures but are arranged as in Figures 1, 2 and 3.
The recording instruments are so arranged that in order to produce a signal the
tongue B, B' must both be on the same section of the drum C at the same time,
the current passing in a similar manner along both. Such position is shown in
Figure 6.
When the arrival current causes the coil A to turn as previously described, both
the tongues B and B¹ are caused to slide into contact with one section of the
drum Cand give a signal in the relay circuit; after a very slight movement how-
ever the tongue B₁ is arrested by the stop b', the tongue B being permitted to con-
tinue its movement under the influence of the coil A, owing to the fact that the
tongue B is only frictionally attached to the said coil. Upon the coil A returning
to its normal position the tongue B will immediately be carried to or across the
insulated strip c thus breaking contact and registering the signal. If the next
signal is of the same sign, the tongue B¹ will be again carried over to the same
section of the drum, even though the amplitude of oscillation of the coil A may
not have been sufficient to cause the fixed tongue B to return to zero between the
signals. For an opposite signal these tongues operate in a similar manner, the
tongue B boing moved to the opposite side or section of the drum and the connec-
tions thus reversed. In this manner the connections for the frictionally controlled
tongue B are changed and a very clear definition of the signals may be obtained.
These two tongues may be arranged on two separate instruinents, the fixed tongue
on one, and the frictionally constrained tongue on another. Or the tongues,
operated by a single coil, may make contact with two separate rotary drums.
Referring to Figure 7. A is the coil suspended in a plane parallel to the north
and south line of the magnet and adapted to receive the arrival currents from the
main line E. C is the rotary drum the sections of which are divided by insulating
material c and connected to one end of the relay circuit F, and G is a recording
instrument all as previously described. H is a suspended rod provided with a cross
piece h. h¹ h¹ are silk cords or their equivalent connecting the ends of the cross
piece with the top of the coil A. B is the tongue which is fixed or frictionally
attached to the suspended rod H, and has one of its ends connected to one end of the
relay circuit and its other end bearing on the rotary drum C. When no arrival
signalling current is received the tongue B rests upon the insulating strip c, and
when the coil A is turned by the arrival signalling current from the main line, as
previously described, such novement is communicated through the cords ' h¹,
cross piece h, and rod H to the tongue B, which latter is cause 1 to slide into contact
with one or other of the drum sections and cause a current to pass through the
relay circuit. By placing the ends of the cords h¹ h¹, which are attached to the
coil A, as far apart as possible, and their opposite ends, which are attached to
the cross piece h, closer together, the end of the tongue B may be caused to move
through a greater angle than the coil A, and its movement thus exaggerated.
These cords do not however form part of my invention.
Referring to Figures 8 and 9, the suspended coil A connected to the main line E,
the magnet a, the tongue B connected to one end of the relay circuit, and recording
instrument G, are arranged as in Figure 1. The rotary drum C is made in a single
piece, revolves in a horizontal plane, and has the other end of the relay circuit
connected to it by a suitable brush f. When no arrival current is being received
from the main line, the tongue B reinains out of contact with the rotary drum as
shown clearly in Figure 9. "When the arrival current from the main line passes

page_text: through the coil A and causes it to turn as previously described, the tongue B´is
moved into contact with the drum C and thus causes a current to pass through
the relay circuit.
It is obvious that instead of employing only one drum C as shown in Figures 8
and 9, two such drums may be employed. Such an arrangement is shown in
Figure 9 in which two drums CC connected to one end of the relay circuit by a
divided battery, are arranged in a position parallel to one another and having a
space between them. In this space the end of the tongue B is normally situated
and is adapted to be moved by the arrival signalling currents so as to make circuit
with one or other of said drums.
Referring to all the foregoing figures, it has been found that the contact between
the end of the relay tongue or tongues and the rotary drum is not quite constant"
in amount, especially when the point of the tongue bears lightly on the said drum.
Any variation in the strength of the current passing, due to this cause, may be
greatly reduced by short circuiting the sliding contact between the tongue and the
drun by a condenser K of suitable capacity."
If the zero of the signals received from the main line is found not to be constant
in position, owing for example to the charging up action of a receiving condenser;"
the relay can be fitted with auxiliary coils arranged in parallel with the working
coil A and receiving current from a secondary circuit; this latter current is before
passing to the auxiliary coil previously sent through suitable contacts (either
moving or fixed) and a circuit having resistance, induction, or capacity, or any com-
bination of these to reproduce the saine variable effects in on the zero, but in the
opposite direction, and thereby eliminate this disturbing factor or variation in of
the zero; from the working of the relay.
The rotary drum may be caused to spin by any convenient means, for example I
may fix the armature of a small electro-magnet directly on the drum shatt. Any
means, (other than the coil described), which are at present known to the art may
be used to impart the necessary motion to the tongue of the relay for the purpose
of indicating received signals.
Referring to Figure 10. E is the telegraph line or cable, and E' E' are conduc-
tors to earth. I is the transmitting instruinent. R is the receiving instrument.
L is an inductive coil or inagnetic shunt having a closed magnetic circuit, with
which the receiving instrument is short-circuited."
Referring to Figure 11, E is the telegraph line or cable, E¹ El are conductors to
earth, and E2 is the artificial line or cable. I is the transmitting instrument the
current from which enters the magnetic shunt L at a mid-point therein. R is the
receiving instrument short-circuited by the magnetic shunt or inductive coil L.
having a closed magnetic circuit.
In the above Figures 10 and 11, the condensers usually placed in series with the
line, are not shown, as such condensers need not necessarily be employed when using
the aforesaid magnetic shunt.
The resistance of the magnetic shunt L is much less than that of the receiving
instrument R; for instance, the resistance of the former may be say 30 ohms and
that of the latter say 500 ohms. The result of the arrangement is that all slow im-
pulses flow through the magnetic shunt L. and leave the receiving instrument R
unaffected, and all sudden impulses, such as the line signalling currents, are resisted
by the magnetic shunt L and therefore affect the receiving instrument R. A varying
zero in the receiving instrument such as is due to slow irregular currents is thus
prevented, a maximum definition of the signals is obtained, and the efficiency of
said signals is consequently enhanced and their speed increased.
The aforesaid closed circuit magnetic shunt may be used with forms of bridge
other than that shown in Figure 11. Figure 12, for instance, shows an arrangement
in which the ordinary condensers K, K are placed in the arms of the bridge. The
receiving instrument R being shunted with the cloud circuit inductive coil L, 1
being the transmitting instrument, E the line or cable, E2 the artificial line, and
E' E the conductors to earth.

page_text: Referring to Figure 13, E is the telegraph line or cable, E', E¹, are the conductors
to earth, E is the arificial line, I is the transınitting instrument, and R is the
receiving instrument, as before. L is the magnetic shunt having a closed magnetic
circuit. is the apex of the bridge to which is pivoted a rheostat or adjustable con-
tact maker J adapted to be moved so as to make contact with any required one of a
number of contacts j' j', each of which contacts j' is connected to a different turn or
part of a turn of the coil forming the magnetic shunt L. The movable contact J is
thus adapted to form a finely adjustable rheostat, by the arrangement of which the
position at which the sending currents enter the magnetic shunt L, can be altered
to suit requirements, and the bridge balance or inductance thus adjusted.
M, M' are movable contact pieces pivoted respectively at m m. The contact piece
M is adapted to make contact with any one of a series of contact pieces m³, and the
contact piece M¹ is adapted to make contact with any required one of a series of
contact pieces m². Each of the contact pieces m² is connected to a different series
of turns at one end of the coil L, and each of the contact pieces m² is connected to
a different series of turns at the opposite end of the coil L. The contact pieces M M
are thus adapted to form coarse adjustable rheostats, by the adjustinent of which
the number of turns of the coil L that act as the magnetic shunt, may be regulated."
N and N', are resistances in the arms of the bridge, and n, n' are movable contact
pieces which are pivoted respectively at n², n³. By moving the contact pieces n, n
so as to connect then at any required point to their respective resistances, the
resistance of the bridge arins may be adjusted.
.. Referring to Figure 14; E is the line, E the artificial line, E' E' the conductore to
earth, I a curb transmitting instrument, R the receiving instrument, and K K the
condensers placed in the arms of the bridge. 12 is a closed circuit self inductive
coil placed in the fork of the bridge and in series with the receiving instrument,
for the purpose of avoiding "jars" on the receiving instrument and th us overcoming
the difficulties of obtaining and maintaining balance introduced by the use of the
curb transmitter.
Referring to Figures 15 and 16, is a hollow iron core of a self inductive coil of
the closed magnetic circuit type. This core is provided with a central bar or
web round which the wire l, forming the coil, is wound. This coil may be made
to possess but little resistance with fair inductance and is therefore particularly
adapted for the purpose of my invention.
Referring to Figure 17, the iron core of the inductive coil comprises three bars
1, 1, 1, which are connected by suitable end pieces. Around the central bar l³ a
coil lo is wound, the ends of which coil are connected to any suitable source of
electricity for exciting said coil, preferably by an alternating electric current.
The
bars 14, are wound respectively with coils 1, 18, which coils are wound in opposite
directions and in series with each other so as to act self inductively.
In this condition currents moving in the two coils will induce no magnetism
in the central iron bar and will therefore have no effect on the central coil, while
on the other hand exciting currents moving in the central coil 1 will produce equal
inagnetic effects in the same direction in the iron bars and will therefore produce
no inductive effect as a whole on the two said outer coils 178 which are as before
stated coupled in series with each other. By thus initially exciting the iron core,
the inductive coil is rendered exceedingly sensitive and its efficiency is consequently
increased.
I find that when the moving surfaces are arranged as in Figures 8, 9 and 9, that
is to say are arranged with respect to the finger so that contact therewith is made
and broken by the free end of the finger moving toward or away from said
surfaces in contradistinction to moving across the said surfaces, the use of a
condenser or condensers, as there shown, is essential to practical success, so that
I make no claim to such arrangements excepting therewith.
I wish it to be understood that I do not intend my claims to include an
inductive coil or magnetic shunt unless said coil or shunt possesses the charac
teristics respecting its high self induction and moderate resistance above stated,

page_text: and unless said coil or shunt be used with submurine cables to shunt the receiving
instrument, under which conditions the usual. receiving condenser or condensers
might as aforesaid be dispensed with.
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, subject
to the above disclaiming notes, what I claim in electric telegraph apparatus
is :-
1. A tongue connected to one end of a relay circuit and adapted to be moved
by the arrival signalling currents so as to make and break circuit between
itself and a moving surface in the relay circuit for the purpose specified.
2. A moving surface connected to one end of a relay circuit and divided by
insulating partitions into sections for making and breaking circuit with a tongue
or tongues connected to the other end of the relay circuit, for the purpose
specified.
3. A receiving instrument short circuited through a closed circuit inductive
coil, for the purpose specified.
4. An inductive coil having a closed magnetic circuit and provided with
means for the initial excitation of its core substantially as and for the purpose
specified.
5. A duplex line in which the sending current enters a closed circuit inductive
coil in the "bridge", which coil is adapted to short-circuit the receiving instru-
ment and is provided with means for adjusting the "bridge balance
purpose specified.
for the
6. A closed circuit inductive coil placed in the fork of the "bridge" of a
duplex line and in series with the receiving instrument, for the purpose specified.
7. Apparatus constructed arranged and operating substantially as described
with reference to any of the examples illustrated by the accompanying drawings
for the purpose specified.
Dated this 21st day of October 1899.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C.
Agents for the Applicant.