Improvements in Rapid Telegraphic Transmission on Cable Lines.
Year: 1895

page_text: Date of Application, 24th July, 1895
Complete Specification Left, 23rd Apr., 1896-Accepted, 24th July, 1896
PROVISIONAL SPECIFICATION.
Improvements in Rapid Telegraphic Transmission on Cable Lines.
I CHARLES LANGDON-DAVIES of 45 Redcliffe Square, Kensington in the
County of Middlesex, Electrician, do hereby declare the nature of this invention
to be as follows :-
1. Electric currents, when passing through sub-marine cables or similar con-
ductors, become elongated, and if they are sent in rapid succession over lap each
other. This is known as retardation and it limits the speed at which distinct
signals can be transmitted in such conductors.
2. The object of my invention is to avoid this elongation of current and therefore
to transmit a greater number of distinct signals in a given time than is now
practicable. I expedite the rise and the fall and limit the duration of each
current.
3. Omitting complex and unnecessary details Figures 1 to 4 represent a current
under ordinary conditions, and also under my improved conditions. In each
figure t. t. is the whole duration in time, a the rise of the current to a maximum
bits duration at the maximum and c its fall to zero. The arrows indicate the
direction in which the currents are supposed to move.
4. Figure 1 shows the ordinary current as it can be derived from the battery,
before it is altered by the retardation of the circuit. It is capable of rising rapidly
to its full strength and of remaining there until it is cut off; but in practice or in
charging a sending condenser a cable or other similar conductor, or any electro-
static, or electro magnetic region, it creates a growing resistance to its own flow,
which resistance increases in proportion as the field becomes charged.
Figure 2 shows the change thus produced; the rise of the current a is slower ;
when it reaches the maximum bit does not remain there because the increasing
resistance of the charge is not met by any increase in the strength of the current,
which therefore falls, elongating c.
The unshaded portion of the figure shows the useful current, the rest may be
regarded as disadvantageous.
5. This resistance of the charge to the current is analogous to that encountered
by an expansive gas when driven at a constant pressure into a closed vessel; the
stream of gas becomes weaker in proportion as the vessel is filled.
It is obvious that a constant strength could be maintained by applying a
constantly increasing pressure and I do this with the electric current.
Instead of a current rising only to a fixed strength and remaining there, I
produce a current which increases in strength throughout the whole period of its
duration.
6. I generate my current by means of an electro motive source capable of giving
a stronger current than I intend to use combined with apparatus which enables the
current to cut itself off from the line at any pre-determined point in its rise.
7. Figure 3 represents the current which can be derived from my generator. It
consists of the rise a and the fall c; there is no duration at b until such duration
is produced by the retardation of the circuit; when the form of the current is
modified as in Figure 4, the rise a is quicker than in Figure 2 the duration 6 due
to retardation, only sufficient to be useful and the fall e but slightly retarded.
8. I further neutralize the retardation, more especially of the fall of the current,
by causing each signal current to be followed at a suitable and adjustable interval,

page_text: by a counter current of opposite sign and of suitable and adjustable strength and
also by the action of my induction generator hereafter described.
9. Although it is possible to use any kind of battery, important advantages
attend an electro motive source of negligible interior resistance and giving a
constant current, such as an accumulator or secondary battery. I combine with
my battery an electro-magnetic apparatus which I call a time break, whese coils
are connected to the battery in parallel with the line circuit. The time break is
furnished with mechanical parts as hereafter described; I so proportion its time
constant to that of the line as to secure that it shall always cut off the current from
the line in time to prevent injuricus electrical stress. The current in the coils of
the time break continues as long as the key is closed. The time break is quicker
in action than the key and its work is always completed, in a period which may be
predetermined, and which is independent of the speed of the key. The currents
sent to line are the same for all speeds of the key; an increase to the battery,
although it increases the speed, does not necessarily increase the strength of the
line current, because the speed of the time-break being also increased, it cuts off a
stronger battery current at an earlier point in its rise. This can be modified by
suitably adjusting the time break so that a stronger battery shall produce either a
stronger or a weaker line current, or make no change in its strength, but only in
the rapidity of its rise.
Opening the key allows the time-break apparatus to return to rest, but sends no
current or discharge to line. I call this combination of battery and time break
my direct generator.
10. I can work with either direct or induced currents in the line circuit. When
I use induced currents I connect the battery and time break to the primary of an
induction coil instead of to the line. I call this combination my induction generator.
The induction coil is wound to produce currents of suitably low potential and I
connect the secondary coil to the line.
The time break is capable of making commutations and of closing a shunt or
shunts in either primary secondary or line circuit.
11. The time break electro magnet when it is excited attracts an armature and
this armature is withdrawn by a counter spring or other counter force when the
magnetism is discharged. The speed of action of the mechanical organs of the
time break depends upon the speed of the armature and the distance through which
its lever has to move I prefer to construct the instrument so that this speed shall
be normally greater than is necessary and I provide means of retarding its action
by increasing the strength of the counter spring by adding non-induction resistance or
a choking coil in series with or as shunts to its coils or by connecting the armature
lever to a pneumatic valve. By varifing the action of these appliances I can
vary the speed of the instrument and I can complete its adjustment with great
delicacy by means of an adjustable iron screw or other keeper applied to two cores
of the electro magnet. The speed of the other mechanical organs can be regulated
by their respective counter springs, and screw stops.
12. The time-break coil may be mounted horizontally and the armature lever
vertically and so that it shall be held to the right by its counter spring or drawn
to the left by the electro magnet. At the end of the armature lever I arrange
either one or two sets of mechanical parts, each set on a separate insulated plate,
those on the left hand or battery plate commutate the direct currents or the
primary circuit, and those on the right hand or line plate the induced currents or
line circuit; these plates also serve as, or to carry, stops to the action of the
armature lever.
13. I provide an adjustment for the line plate so that without disturbing the
adjustment of the parts mounted on it, the whole plate may be moved to or from
the armature lever. When there is no line plate, as is often the case when the
circuit is to be worked by direct currents only, I provide an adjustable stop instead.
The object of this adjustment in each case, is to vary the distance through which
the armature lever moves, thereby regulating the interval between the closing of

page_text: the key and the automatic cut off of the current, whereby the strength of the line
current is governed.
14. The battery plate may be furnished with a similar adjustment but this is
seldom necessary it is preferable to fix the plate in the best position for the action
of the electro magnet on the armature.
15. The mechanical parts on the line plate are furnished with springs arranged
to put them in action when they are free to move they are held against these
springs in the position of rest by the armature lever drawn by its counter spring.
This counter spring must therefore be stronger than the minor springs, and
each of the latter need only be strong enough to move its part and make good
contact.
16. The parts on the battery plate are held in position by similar springs
until they are moved against their springs by the pressure of the armature lever
drawn by the electro magnet.
:
17. The mechanical parts of each plate consist of moving levers and stops or
screws for making a breaking contact. Some of the stops are provided with
special springs and contact pieces to maintain contact with the lever, for a time,
while it is moving and until the contact is broken by a fixed pin or a screw, a
similar arrangement permits of delay in making a contact. The parts are adjust-
able towards each other so as to regulate the make, break, duration of contact, and
length of interval between each commutation.
18. The process of direct current working is as follows ;-
A. The sending key is closed, the current begins to rise in the line circuit, and
also in the time-break coil whose armature lever commences its movement.
B. The armature lever approaches the battery lever which is pivotted on the
battery plate; during the interval so occupied the line current is rising.
C. The armature lever touches the battery lever and breaks the lead to line,
thereby cutting off the line current but not the current through the time-break coil.
I usually place a condenser across this contact.
D. The battery lever approaches the shunt screw and in so doing, occupies. a
period which can be regulated by means of the screw; this gives time for the
necessary retardation of the line current.
E. The battery lever touches the shunt screw closing the line circuit across the
transmitting apparatus to earth or otherwise, and the shunt may contain a resistance
or condenser. The line current falls rapidly, the speed of its fall can be accelerated
if necessary by causing the time-break to admit any curbing current as a counter
current. This is generally unnecessary when a sending condenser is used.
19. The process of induction current working is as follows;-
A. The sending key is closed, the current begins to rise in the primary circuit,
inducing a current in the secondary or line circuit, which is the signal current; its
rise can be modified by regulating the core of the induction coil. At the same
time the current rises in the time-break coil and the armature lever commences its
movement, allowing the line lever pivotted on the line plate, to leave its stop, this
is used to open a shunt when the current induced at make has been modified by
shunting the whole or a portion of the secondary coil either directly or through a
resistance. A following contact is necessary for this, to prevent the shunt from
being opened too soon.
B. The armature lever approaches the battery lever; during the time so
occupied the current rises in the primary, and the line lever closes a shunt to the
secondary coil through a resistance or otherwise, ready to regulate the line current
induced by breaking the primary.
C. The armature lever touches the battery lever and breaks the primary circuit ;
the resulting induced current goes to line, modified or not, as before described, and
is the counter current. The battery current continues in the time-break coil.
:
D. The battery lever touches the shunt screw, closing the disconnected primary
coil on itself.
20. When this induction system is used a current will be produced in the

page_text: .
secondary or line circuit at each make, and each break of the primary circuit.
When I use the make current as the signal current, the break current is used as
the counter current and may be modified as described, by means of the line lever of
the time-break and otherwise.
21. It is often advantageous to use the induced break current as the signal
current. When I do this I can increase its efficiency by shunting the whole of the
secondary coil and also a condenser, which may be a sending condenser in the line
circuit by means of the line lever, so that the shunt remains closed while the
induced make current rises, the two ends of the secondary being then connected to
the two plates of the condenser. The shunt is open when the primary is broken,
the discharge from the coil re-enforces the discharge from the condenser, and the
resulting current in the line rises with great rapidity. I can obviate retardation in
the fall of this current by causing the time-break to shunt a portion or the whole
of the condenser after sufficient current has left it, so that it shall discharge the
slower portion of its flow through the shunt, or I cause the time-break to close a
circuit through a battery an electro magnet and a break, which sends the necessary
counter current at the proper moment. I find it often sufficient to connect a
condenser across the battery so that it shall be charged at the same time as the
primary coil; they are disconnected by the time-break from one pole of the
battery, and then joined so that the condenser discharges into the primary and
produces a counter current.
The
22. I can use any suitable finger or other key but I prefer to use an automatic
sender such as the Wheatstone automatic transmitter, modified to send marking
signals only and to reduce the proportion of time when the key is kept open.
spacing in my system is done by the time-break and it is only necessary to open
the key long enough to allow the time-break to return to rest.
23. My apparatus is connected to the line wire or cable with or without con-
densers in circuit or otherwise, and arranged for simplex or duplex working as may
be required.
Dated this 24th day of July 1895.
CARPMAEL & Co.,
Agents for the Applicant.
Improvements in Rapid Telegraphic Transmission on Cable Lines.
I, CHARLES LANGDON-DAVIES of 45 Redcliffe Square, Kensington in the
County of Middlesex, Electrician, 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 :-
1. Electric currents when passing upon submarine cables or similar conductors,
become elongated, and if they are sent in rapid succession, overlap each other.
This is known as retardation, and it limits the speed at which separate signals can
be transmitted on such conductors.
2. The object of my invention is to avoid this elongation of current and
therefore to transmit a greater number of distinct signals in a given time than is
now practicable. I expedite the rise and the fall, and limit the duration of each
current.
3. Omitting complex and unnecessary details Figures 1 to 4 sufficiently illustrate
a current under ordinary conditions, and also under my improved conditions. In
each figure tt is the whole duration in time, a the rise of the current to a maximum,
bits duration at the maximum, and c its fall to zero. The arrows indicate the
direction in which the currents are supposed to move..
4. Figure 1 shews the ordinary current as it can be
.:..
'
derived from the battery,

page_text: unaltered by retardation of the circuit. It is capable of rising rapidly to its full
strength & of remaining there until it is cut off; but, in practice, or in charging a
sending condenser, a cable or other similar conductor, or any electro-static, or
electro-magnetic region, it creates a growing resistance to its own flow, which
resistance increases in proportion as the field becomes charged. Figure 2 shews
the change thus produced; the rise of the current a is slower; when it reaches the
maximum bit does not remain there, because the increasing resistance of the charge
is not met by any increase in the strength of the current, which therefore falls,
elongating c. The unshaded portion of the figure shows the useful current, the rest.
may be regarded as disadvantageous.
5. This resistance of the charge to the current is analogous to that encountered'
by an expansive gas when driven at a constant pressure into a closed vessel; the
It is obvious that a
flow becomes weaker in proportion as the vessel is filled.
constant strength of flow could be maintained by applying a constantly increasing
Instead of a current rising only
pressure and I do this with the electric current.
to a fixed strength and remaining there as long as it is required, I generate a.
current which continually increases in strength throughout the whole time of its.
duration.
6. My generator consists of an electro-motive source capable of giving a stronger
current than I intend to use, combined with apparatus which cuts off the current
at any pre-determined point in its rise. The effect of this is equivalent to a
reduction of the time constant of the circuit, as is illustrated in the diagram
Figure 5. In any given circuit t t is the time constant say ten; tv the normal
working current; TV the rise to efficiency of this current under a ten-volt
pressure. Now t N is the first portion of the rise of a current under a hundred-
volt pressure in the same circuit. It reaches the ten-volt line in one-tenth of the
time required under the ordinary ten-volt pressure, and, since it is then cut off by
my apparatus, the approximate result in the circuit is an effect, like that obtained
with ten volts but in one-tenth of the time required by the methods hitherto
in use.
This proportion may be reduced or greatly increased by suitable
arrangements.
7. Figure 3 illustrates the current which can be derived from my generator as
compared with Figure 1. It consists of the rise a and the fall c but is without
appreciable duration at b. Figure 4 is this current as altered by the circuit; the
rise a is quicker than in Figure 2, the duration at b only sufficient to be useful,
and the falle varied by a retardation so slight as to be in many cases negligible.
When it is necessary I further reduce the retardation, more especially of the fall
of the current by causing each signal current to be followed at a suitable and
adjustable interval by a counter-current, or curb, of opposite sign, and of suitable
and adjustable strength.
8. In constructing my generator it is possible to use any kind of battery, but
important advantages attend the employment of an electro-motive source of
negligible interior resistance, and giving an approximately constant current such
as an accumulator or secondary battery. I can employ apparatus driven by hand
or mechanical power to cut off the current, but it is greatly preferable to use my
electro-magnetic time-break hereafter described, which enables the current to cut
itself off automatically at any predetermined point in its rise.
I connect
9. Figure 6 is an elevation of the electro-magnet of the time-break.
the coils TBC to the battery in parallel with the line circuit in such a manner as
to ensure that the current shall flow in the coils TBC as long as the sending key
is pressed (and notwithstanding that the current from the same battery becomes
cut off from the line circuit), and further so that when the key is raised the
currents shall cease in T B C, thereby allowing the time-break apparatus to return
to rest, without causing a current or discharge in the line. The time constant of
the electro-magnet is always less than that of the line, and I so proportion it as to
secure that the current shall always be cut off from the line before the sending. key
is opened and in time to prevent injurious electrical stress. I prefer that the

page_text: resistance of the coils should be comparatively low, say 400 ohms or thereabouts in
each, and I employ an exterior rheostat in series with them, as a regulator;
I construct this and other regulating rheostats referred to hereafter, of non-
inductive resistances, or of impedance or choking coils, or partly of each, and I use
these when required together or separately in all proportions and with or without
other appliances as may be necessary to regulate the current flowing through them.
The coils TBC are provided with iron cores which may be three-eighths of an
inch in diameter and two inches in length, and they have returning pole pieces P P
Figure 7, at the back. The pole pieces do not quite meet, and a suitable
cavity CA is arranged to receive the taper end of the iron screw IS Figure 6, by
means of which the adjustment of the speed of the timebreak can be completed
with great nicety. The iron armature A A in front of the cores is fixed on the
lever E and drawn away from the core by the counter-spring CS 1, which is a
watch-mainspring, whose strength is regulated by a worm and worm wheel. The
lever E projects through an aperture in the plate V of the timebreak and sets the
mechanical apparatus in motion, the parts A, D, a b, C, D, indicated in Figure 6
are more particularly referred to in the description of Figure 8 which follows.
10. Figure 8 is a plan of the plate V of the timebreak with the mechanical parts
mounted thereon. E is the end of the armature lever as it is held in the position
of rest by the counterspring C S 1, Figure 6; it is capable of being drawn in the
direction of the arrow by the magnetism of the cores of the electro-magnet.
A B, A B, is the line plate or as I prefer to call it the sliding-plate or slide,
carrying the pivotted beam a b with its adjustable counterspring CS 2, the screw
stop A and the insulated contact screw B2; the movement of the slide does not
alter the adjustment of these parts towards each other. In the position of
rest, ab is held against the screw A, the counterspring CS2 is strained, the
lever E presses on the beam, and the contact between the screw B2 and the
beam a b is open. The position of the slide is regulated by the gauge screw G,
working in a standard g 1 fixed on the sole plate, and turning in the standard g 2
fixed ou the slide. This screw may have fifty turns to the inch; a pointer moving
with the slide shows on a scale fixed on the sole plate the turn at which the slide
is at any moment adjusted, while the scale on the collar g3 divided into say
20 divisions, and turning with the screw, shows to what part of that turn the
adjustment has been made. The distance through which the lever E can move
towards the screw D depends upon the position of the slide. The interval between
the pressing of the sending key and the cutting off of the line current is determined
by it; other things being equal, the strength of the line current is therefore
governed by the position of the slide, which can easily be regulated by the screw G
to say the ten thousandth part of an inch. The battery plate V V V V, or as
I prefer to call it, the sole plate is preferably of non-conducting material;
although it may be made adjustable it is advantageously fixed in that position
which is best for the action of the electro-magnet on the armature. Mounted on
this plate are the pivotted beam CD and its counterspring CS3, the contact
screw C 2 and the contact stop screw D. The beam and screws are insulated, and
the beam is held, in the position of rest, against the screw C2 until it is moved by
the lever E.
11. I can work with either direct or induced currents in the line circuit. The
timebreak described serves for both methods, but when working direct the
movement of the beam ab is not required; the screws A and B2 are therefore
arranged to prevent such movement, or the beam and the screw B2 may be
dispensed with. The slide under these circumstances acts only as an adjustable
stop. Figure 9 shows the connections for direct working. ET is the earth
terminal. L the line terminal, FT I term the furcating terminal. Connected in
series between FT and ET are the timebreak coils TBC and the rheostatic
regulator R 1. The automatic or mechanical sender or finger key K K with its
battery, are also connected between E T and F T. The mechanical parts of the
timebreak are connected between FT and the line L. The screw C 2 Figure 8 is

page_text: connected to FT, the beam CD to L and the screw D, by a shunt wire, to E T.
The direction of the magnetic pull on the armature lever E is indicated, in all
cases, by an arrow. Figure 10 shows the organs in the line circuit before the key
is pressed; they are, first the line, second the beam CD third the screw C 2,
fourth a local circuit closed on itself composed of the timebreak coils the rheostatic
regulator and the key, and last the earth. On pressing the key the current rises
in the line and also in the local timebreak circuit, and is cut off from the line by
the separation of the beam C D from the screw C2, at a point predetermined as is
hereafter described. The duration (6 Figure 4) is limited and the fall of the line
current is expedited by the closing of the line to earth through C D and the shunt
wire and screw D. Figure 11 shows the circuit in this condition, after the time-
break has acted, but before the key is raised. The effective duration of the
current (b Figure 4) bears a proportion or relation to the length of the interval
between the opening of CD from C2 and the closing of CD on D; it can be
regulated by either C2 or D but preferably by D. Resistance, capacity, or lag
can be inserted in the shunt wire D when required, to modify the duration or fall
of the current. I call this combination of battery and timebreak, my Direct
Generator.
12. When I wish to work with induced currents in the line circuit, I connect
the battery and timebreak to the primary of an induction coil; I call this
combination my Induction Generator. I wind the induction coil to induce currents
of suitably low potential; a primary of 7,000 turns and a resistance of about
230 ohms, with a secondary of 7,000 turns and a resistance of about 300 ohms
would be suitable. A core three inches long and oue inch in diameter would be
suitable to the coil described.
13. When working as an induction generator, the beam ab of the timebreak
Figure 8 commutates the line circuit. Its counterspring CS2 is arranged to
make contact at B2 but is prevented from doing so as long as the counter-
spring CS1 Figure 6 of the lever E is not overpowered by the pull of the
electro-magnet. Figure 12 shows the connections for induction working; ET is
the earth and L is the line terminal; the secondary of the induction coil is
connected between them; the earth terminal ET is also connected to the beam a b
of the timebreak, the line terminal L is connected through the rheostatic
regulator R 2 to the contact screw B2; the organs a b, B2 and R 2, thus
constitute an adjustable shunt to the secondary coil. The local timebreak
circuit TBC, K1, KK, is arranged as in the case of direct working, the
terminal FT being connected to the contact screw C2; but the beam CD is
connected to one end of the primary coil P 2 instead of to the line; the other end
of the primary is connected through a rheostatic regulator R 3 to P1 instead of to
the earth. The local timebreak circuit also includes P 1. To absorb the spark at
the break between CD and C 2, I connect a condenser between P1 and P 2. To
perfect the discharge from the primary coil and the core, and to expedite the fall
of the secondary current, I connect the shunt wire from P 1 to the screw D; and
to eliminate any spark which may appear on the approach of the beain CD to D,
1 insert a small resistance, say 200 ohms more or less, at r, in the shunt wire D.
Figure 13 shows the organs in circuit before the sending key is pressed. The
secondary coil only is in the line. Between the terminals P1 and P2 are, first
the primary coil and rheostatic regulator R 3, second, the spark condenser, third,
the closed timebreak circuit R 1, TB C, KK, the screw C 2 and the beam CD ;
these three systems are shunts inter se. On closing the key, the battery current
rises in the timebreak and also in the primary coil. The current induced in the
secondary rises in the line circuit and is the signal current. The movement of the
lever E allows the beam ab to close on B2 which limits the duration 6 Figure 4,
the signal current then falls-the fall is expedited and the retardation practically
obliterated by the discharge from the induction coil consequent on the breaking of
the primary circuit from the battery at CD, C 2. This discharge being properly
timed reinforces the discharge from the sending condenser and is generally more

page_text: than sufficient; it can be reduced by regulating the screw D which can be adjusted
to close the primary circuit on itself at any point in the discharge. Figure 14
shows the organs in circuit at the moment when the lever E has moved far enough
to allow a b, B2 to be closed, shunting the secondary and thereby either entirely
arresting the rise of the signal current in the line, or, by regulating the shunt R2,
only so far reducing it as to permit it to acquire, assisted by the retardation of the
circuit, a required duration 6 Figure 4. Figure 15 shows the organs in circuit at
the moment when, after the lever E has broken the primary circuit at C 2 and
before it has shunted the primary coil at D, the discharge takes place which is
necessary to expedite the fall of, and curb the signal current; this curb is
accurately regulated by the screw D.
14. When necessary for direct working, and in some cases, also for induced
working, I can accelerate the fall of the signal current and obviate its retardation
by causing the timebreak to admit any curbing current into the line, which curbing
can be expedited by deriving the current from one of my generators. I however,
prefer my condenser curb, consisting of an adjustable condenser arranged to receive
its charge when the signal current is sent to line or primary. This condenser is
maintained at its maximum charge by the battery in order that when the curb
current is discharged into the line or primary it shall be rapid. Figure 16 shows
in plan the modificatious necessary in the mechanical organs of the time break to
carry this out. The pivotted beam D 1 has a non-conducting boss at one end
which is kept by the counterspring CS4 resting on or towards the beam C D, so
that the two beams move together under the action of the lever E. The contact
screw D 5 is a following contact, that is to say, its platinum contact pin is held in
position outwards by means of a spring within the shank of the screw, and can
retire a short distance without breaking contact, when pressed by the beam D 1.
The stage D 4 carries a pivotted lever having a platinum wheel pw arranged to
make contact with either the beam D1 or the beam CD but not with both at the
same time; this stage is provided with a counter spring and stop screw to regulate
the position of the wheel. The other parts of the time break are similar to the
same parts shewn in Figure 8, but are connected in circuit somewhat differently.
15. Figure 17 shows the connections when using the curb condenser for direct
working the plates of the curb condenser CC are connected respectively to the
beams CD and D1; the platinum wheel D4 is connected to earth ET; the
following-contact D5, which works on beam D1 is connected to line L, and
the contact screw C 2 which works on bean CD, is connected to the furcating
terminal FT; the screw D2 is connected to a shunt wire, which may contain a
resistance for the suppression of sparking, so that when CD touches D2 the plates
of the condenser are connected through the shunt wire. The lever E is connected
to the battery through F T, and the beam ab to line, the screws A and B 2 act
only as stops. In the time break shewn in Figure 8 the line current was cut off
by the separation of the beam C D from the screw C 2, but in Figure 17 this is
done by the separation of the lever E from the beam a b. This separation does
not take place at the beginning of the movement of E because the beam a b can
follow that movement without breaking contact until the screw B2 is reached.
The interval so occupied is the time during which the battery current is permitted
to rise in the line; it depends upon the speed of the lever E and the distance
through which the beam a can follow it; it is therefore regulated partly by the
screw B2 aud, with greater nicety, by the variation of the proximity when at rest
of the armature of E to the cores of the electro-magnet, as adjusted by the screw G.
The time break circuit T BC, R 1, K K is arranged as before.
16. Figure 18 shows the positions of the organs in circuit when the time break
is at rest, and before the sending key is pressed. The battery, the time break
coils, and the curb condenser, are shunts inter se, and the line circuit is completed
through E and the beam a b. Figure 19 shows the organs in circuit when the line
current is cut off by E. The curb condenser is now charged and its charge is
being maintained by the battery. The further movement of E brings its insulated

page_text: side upon the beam CD Figure 16 which is moved towards D2, but, before
touching D2 it makes the following commutation:-CD is separated from C 2
and connected to the wheel D4; by the same movement D1 is separated from
the wheel and connected to D 5; the plates of the curb condenser are thus reversed
and the circuit is in the condition shown in Figure 20 where the curb condenser is
discharging to line. The movable contact pin of D5 permits the beam CD to
touch D2 but only after the discharge has commenced; this stops the discharge
of the curb to line at a point adjustable by the screw D2. Figure 21 shows the
circuit in its final condition before the key is raised; the line being closed through
a negligible resistance. For induction working with the curb, the connections are
similar but the primary coil is connected in place of the line circuit; the secondary
coil is connected to line and earth as before described.
17. It is sometimes advantageous, in induction working, to use the secondary
current induced at the break of the primary, as the signal current. When I do
this, I can increase its efficiency by shunting the whole of the secondary coil and
also a condenser-which may be a sending condenser-in the line circuit, so that
the shunt remains closed while the current induced at the make, rises, the two ends
of the secondary being connected to the two plates of the condenser. Figure 22
is a diagram of modifications in the line connections necessary for this purpose.
The connections in the primary circuit remain as they are shewn in Figure 12.
The screw A of the time break, is provided with a moving contact pin similar to
that of D 5, Figure 16; it is insulated from the slide and beam A B and connected
to the secondary, say on the earth side; the beam ab is connected to the line side
of the condenser S. C. This arrangement is a shunt to the secondary coil and
condenser and is closed in the position of rest; it remains closed after the lever E
has commenced moving, because a b is followed by the contact pin of the screw A.
It is opened before E breaks the primary circuit by the separation of the beam CD
from C2; the discharge from the coil then re-enforces the discharge from the
condenser, and the resulting current in the line rises with great rapidity. I expedite
the fall and obviate the retardation of this current if necessary by the methods
previously described.
18. As a sender, I can use any suitable finger or other key but I prefer an
automatic sender, such as the Wheatstone automatic transmitter, modified in a
well known manner to send marking signals only, and to reduce the proportion of
the time when the key is kept open. In my system the spacing is done by the
time break and it is only necessary to open the key for the exceedingly brief
period required by the time break to return to rest.
19. I can connect my apparatus to the line or cable with or without condensers
or other apparatus in circuit or otherwise, and when the circuit is arranged for
simplex or duplex working, or in any other way required. As a general rule I can
employ any suitable circuit as I find it, by simply using, in place of the battery,
one of my generators as above described, consisting of a battery and time break
with or without a curb condenser, induction coil and other accessories.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
:-
1. In telegraphic transmission on cable lines, the use, substantially as described,
of an electro-motive source capable of giving a relatively strong current, together
with apparatus which disconnects the source, after a predetermined interval and
long before the current attains the full strength which the source is capable of
yielding.
2. In telegraphic transmission on cable lines, the use, as stated in Claim 1, of a
powerful electro-motive source, and apparatus which disconnects the source before
the current attains the full strength, in combination with an appliance which
forwards a counter current of suitable and adjustable strength and duration after
the signal current and thereby accelerates its fall.

page_text: 3. In telegraphic transmission on cable lines, transmitting appliances sub-
stantially as described in respect to Figures 9, 10 and 11 whereby on the key
being closed an electro magnet which shunts the key is caused to attract its
armature and thereby to move parts which at suitable and adjustable intervals
after the closing of the line or signal circuit by the key open the said circuit and
then put the line to earth.
4. In telegraphic transmission on cable lines, transmitting appliances. sub-
stantially as described in respect to Figures 12, 13, 14 and 15, whereby an electro
magnet is caused to move parts which at suitable and adjustable intervals after
the closing of a primary circuit by the key again open the primary circuit and
afterwards close the primary coil upon itself, whilst the secondary coil remains
throughout connected to the line circuit.
5. In telegraphic transmission on cable lines, transmitting appliances wherein
substantially as described in respect to Figures 12, 13, 14 and 15 an electro
magnet brought into action by closing the key in addition to performing the
functions stated in Claim 4 moves parts which at a suitable and adjustable time,
relatively to the time of the other movements close the secondary circuit upon
itself.
6. In telegraphic transmission on cable lines, transmitting appliances wherein
substantially as described in respect to Figures 12, 13, 14 and 15 an electro
magnet brought into action by closing the key first closes the secondary coil on
itself through an adjustable resistance and then opens the circuit of the primary
coil, thereby causing an adjustable curbing current to follow the sigual current.
7. In telegraphic transmission on cable lines, transmitting appliances wherein,
substantially as described in respect to Figures 17, 18, 19, 20 and 21, an electro
magnet, brought into action by the closing of the key, first causes a graduated
signal current to pass into the line and then discharges a condenser whereby a
curbing current is made to immediately follow the signal current.
8. In telegraphic transmission on cable lines, transmitting appliances, sub-
stantially as described, in respect to Figure 22, whereby an electro magnet
brought into action by the closing of a key closes and opens a primary circuit and
also controls a shunt around a secondary coil which with a condenser is in the line
circuit; the arrangement being such that the shunt being closed the secondary
current resulting from the closing of the primary circuit is diverted from the line,
whilst the opening of the shunt permits the current resulting from the opening of
the primary circuit to pass.
9. Telegraphic transmission apparatus substantially as described and illustrated
by the annexed drawings.
Dated thin nond
A
11000
C. LANGDON-DAVIES.