Improvements in Electric Telegraphs for Ships and other Purposes.
Year: 1899

page_text: Date of Application, 13th June, 1899
Complete Specification Left, 12th Apr., 1900-Accepted, 13th June, 1900
PROVISIONAL SPECIFICATION.
Improvements in Electric Telegraphs for Ships and other Purposes.
We EVERSHED & VIGNOLES LTD., of Woodfield Works, Harrow Road,
London, W., Electrical Engineers, and SYDNEY EVERSHED, of the same address,
Electrical Engineer, do hereby declare the nature of this invention to be as
follows:-
This invention relates to electrical apparatus for the transmission of pre-
arranged signals and is applicable for any purpose where a limited number of
definite signals or orders are required to be transmitted from one position and
indicated on a dial or otherwise at another position; and is more particularly
applicable for engine room, steering, docking and other telegraphs required on
board ship.
Our invention is based on the same principle as the telegraphic systems for
similar purposes described in the Specification of Patent No. 8784, 1891,
namely that the signal or order shown by the indicating apparatus (hereinafter
referred to as the indicator) depends only on the ratio of the currents in two
circuits fed from a common source of E.M.F. and not on their absolute value,
so that the indications given are not affected by variations in the E.M.F. applied
in common to the said circuits and the transmitting devices (hereinafter referred
to as the transmitter) described in the said specification may, with certain modi-
fications to be presently described, be employed in carrying out our present
invention which relates more particularly to the means by which the ratio of
the currents in two circuits (hereinafter referred to as the ratio circuits and
distinguished as the A circuit and the B circuit respectively) determines the posi-
tion of the index or other indicating appliance on the dial or scale of the
indicator.
The essential parts of an indicator made in accordance with our present inven-
tion are a number of differentially wound electromagnetic devices (hereinafter
referred to as "movements") similar to the well known polarized relays commonly
used in telegraphy, but without their contact devices. Each of these move-
ments comprises a permanent magnet or magnetised tongue (hereinafter referred
to as a tongue) fixed on and at right angles to an axle and capable of limited
angular rotation between two stops (hereinafter referred to as the positive and
negative stops respectively. The tongue moves in the magnetic field of a
differentially wound coil which may contain an iron core or cores. The two
windings of the coil (hereinafter called the A winding and B winding of the
movement) are connected respectively to the two ratio circuits and the ratio
currents being caused to flow through the two coils in opposite senses the direc-
tion of the resultant magnetic field will depend on the relative strength of the
magnetising forces of the two windings, and the tongue will rest against one
stop or the other according to-the direction of the said resultant field.
A simple form of indicator may be made by arranging a number of such
movements in a row behind a longitudinal slot in a dial. Each movement
carries a light shutter on a rod extending radially from and attached to its axle

page_text: and the shutter is curved so as to form part of a cylinder of large radius con-
centric with the said axle. The movements are so fixed with relation to the
dial as to cause their shutters to take up positions side by side immediately
behind the slot, the whole series of shutters forming an almost continuous and
nearly flat surface, the axles of the movements being arranged in line with
each other and parallel to the length of the slot. Each shutter has one half of
its surface painted black and the other half white so that either the black or the
white portion is visible through the slot in the dial according to whether the
tongue is resting against the positive or negative stop.
With this type of indicator the number of movements is equal to the required
number of signals. The signals are marked on the front of the dial in succession
beside the slot; for example, if the signals are a series of numbers the figures
will begin with zero at one end of the slot and end with the maximum required
figure at the other end of the slot.
The movement coils are connected so that all the A windings are in series
with each other and with the A circuit, and all the B windings are similarly
connected in series with the B circuit. The number of turns of wire on the
coils of each movement is determined by means of the following definite and
simple law, that is to say supposing a current of suitable value requires to be
reversed through T turns of wire in order to move a tongue from the positive
stop to the negative stop the A winding of the first movement must have
T turns of wire, that of the second movement, will have 2×T turns, of the third
3×T turns, and so on up to the last or Nth. movement which will have NXT turns
of wire on the A winding. The B windings follow a reciprocal law, that is
to say there are Nx Tturns in the 13 winding of the first movement (N-1) x T turns
in the next, and so on up to the last movement which will have T turns in its
B winding.
With this arrangement of windings any number of successive movements can
be made to show the black portions of their shutters through the slot in the dial
and the remainder their white portions by suitably regulating the ratio of the
currents in the A & B circuits. For example, when the A current is equal to
the B current it is evident that in one half of the total number of movements,
namely from the movement at one end of the slot up to the centre of the length
of the slot, the B winding will predominate and cause the black portions of the
shutters to appear through the slot, while in the remaining half of the movements
of which the indicator is composed the white portions of the shutters will be
visible.
If now the ratio of the B current to the A current is increased the tongues
which are resting against the negative stops and therefore showing the white
portions of their shutters will reverse one after another, beginning with the one
next the last tongue which is resting against its positive stop.
On the other hand if the ratio of the B current to the A current is diminished
there are similar successive disappearances of the black portions of the shutters.
Thus the length of slot appears to be partly black and partly white and the black
part appears to advance and recede along the slot as the ratio of the B to the
A current is increased or diminished, and the signals are read much in the same
manner as the temperature is read on an ordinary mercury thermometer by the
position of the end of the thread of mercury on the scale.
When the signals to be transmitted are numerals we may have two or more
slots in the dial of the indicator and provide each slot with ten movements. The
first slot will then serve to indicate the digit in the units place of any required
numeral, the second slot will indicate the digit in the tens place and third slot
will indicate the digit in the hundreds place, and so on, so that a two slot indicator
will show any numeral from 1 to 100, a three slot indicator will show any
numeral from 1 to 1000, and so on. The series of movements belonging to each
slot will be connected to a separate ratio circuit controlled by a separate multiple
point switch and resistances in the transmitter, so that there will be as many

page_text: independent ratio circuits as there are slots. These ratio circuits may either be
coupled in series or in parallel with each other, and the multiple point switches
may be coupled mechanically together if it is desired to make all possible signals
by means of a single handle on the transmitter.
"
Indicators of the type described above may be and are herein called "slot
indicators to distinguish them from a modification in which the series of dif-
ferential movements is made to control the position of an index on a circular
dial, a type of indicator which may be and is hereinafter called a circular
indicator."
·་
In one form of our circular indicator the movements are arranged symmetrically
and equally spaced round a circle (hereinafter referred to as the movement
circle) having its centre on the axial line passing through the index axle and
its plane parallel to that of the dial and at a suitable distance behind it. The
rotational axis of the axle of each movement is a tangent to the said circle so
that the tongues are free to move in planes radial to the axis of the index axle.
A pin or rod of suitable length is attached to and moves with the axle of each
movement, its motion being limited by suitable positive and negative stops as
in the slot indicator. These movement pins project inwards towards the said
axial line and their ends lie on one or other of two circles concentric to the said,
axial line and parallel to each other) according to whether the corresponding
tongues are against the positive or the negative stops. These two circles are here-
inafter referred to as the positive and negative pin circles. The movement circle
and the pin circles are of course only imaginary lines by which the positions of
the movements and their pins are conveniently specified. The pin circles as
described are necessarily smaller in diameter than the movement circle and they
are symmetrically disposed on each side of the plane of the movement circle.
The necessary relation between the positions of the pins and that of the index
on the dial is established by means of an electromagnetic mechanism hereinafter
referred to as the driver mechanism."
..
It consists of an inner axle (in line with the index axle but not attached
thereto) carrying at one end a radial arm adapted to rotate in the plane of the
positive pin circle and having a plate or catch at its outer end adapted to impinge
on any movement pin which may be in the said plane.
A sleeve on the inner axle and capable of rotating freely thereon carries a
second and similar arm adapted to rotate in the plane of the negative pin circle
and impinge on any movement pin which may be in the plane of the said negative
pin circle. The inner axle and the sleeve are connected together by means of
a coiled spring which is always in torsion so that the two arms tend to rotate
in opposite senses.
These two arms may be and are herein called drivers "and they are dis-
tinguished as the positive driver and the negative driver because they rotate
respectively in the plane of the positive and negative pin circles.
The action of the coiled spring causes the positive driver to rotate (missing
all the pins which are on the negative pin circle) until it comes in contact with
the first of the pins which is on the positive side. All the pins beyond this
one will be on the positive side also, so that the spring will at the same time
cause the negative driver to pass all these pins until it comes in contact with
the first of the negative pins, that is to say the one next to that with which
the positive driver is in contact. Thus the coiled spring rotates the drivers
until they rest against adjacent pins. When in this position they are not quite
in the same radial plane and a rod or crank pin projecting back from a crank
arm fixed on the index axle passes between them in a direction parallel with
their common rotational axis. Since the crank pin cannot pass the drivers its
angular position with respect to its rotational axis and consequently the position
of the index on the dial will be governed by and depend upon the position of the
two drivers when they are resting against the movement pins.
The inner axle is connected by suitable gearing with the armature of an

page_text: electro-magnet hereinafter referred to as the "driver magnet." The sleeve on
the inner axle is similarly connected to a second and independent armature adapted
to be attracted by the driver magnet. When the driver magnet is excited its
attraction on the two armatures opposes and overcomes the torsion of the coiled
spring so that the two drivers fly rapidly backwards until they are beyond the
first and last movement pins; here they each come in contact with suitablo
stops against which they rest so long as the driver magnet is excited. When
the drivers are so resting against the stops the movement pins are free to take
up their positions against the positive or negative stops according to the ratio
of the currents in the A & B circuits.
The windings of the movements are arranged according to the law already
described in connection with our slot indicator and the position of the movement
pins is therefore governed by the ratio of the B current to the A current in the
same manner also. The driver magnet winding is in the return circuit so that
the sum of the A & B currents traverses its coil.
.
Our circular indicator only requires the current to be on while a signal is
being made, and we therefore modify the transmitter described in Patent
No. 8784, 1891, by providing it with a switch so connected with the transmitter
handle that it is impossible to move the latter without first closing the switch,
and as soon as the handle is brought to the desired signal the switch is released
and automatically opens the circuit and at the same time locks the handle in
place. When it is desired to indicate a new signal or order on the indicator
dial the switch is first closed thereby unlocking the handle and at the same time
causing the current to flow through the ratio circuits and thence through the
winding of the driver magnet. The attraction of the driver magnet armatures
causes the drivers to fly back against their two stops clear of the movement
pins. The transmitter handle then being moved over the contacts towards the
one which corresponds with the desired signal, successive tongues in the
indicator reverse as the transmitter handle passes over successive contacts. When
the handle is brought to the contact corresponding to the desired signal it is
locked there by opening the switch and the current being thereby stopped the
driver magnet ceases to be excited and its armatures cease to be attracted. The
coiled spring thereupon causes the drivers to fly forward until they rest against
adjacent movement pins again, the particular two depending of course on the
ratio of the B current to the A current at the instant when the switch was opened.
The crank pin being between the two drivers is forced by their movement into
the new position they have now taken up and the index consequently points to
the desired signal.
By observing suitable proportions between the forces acting on the drivers
and the moment of inertia of the moving parts of the driver mechanism, the
time occupied by the drivers in moving backwards from the movement pins to
the driver stops, may be made so short that it is quite impossible for the trans-
mitter handle to be moved by hand from one contact to the next before the
drivers have reached the stops and consequently the drivers are always
quite clear of the movement pins before any of the tongues reverse their
positions. As an additional precaution to ensure certainty of action the plates.
or catches at the ends of the drivers may be so shaped on one side that they
cannot when moving backwards catch on any movement pin which might acci-
dentally be on the wrong circle. This is readily effected by making the catch in
the form of a hook or V notch on its forward side so as to catch and lock the
pin against which it is impinged when the current is cut off, and by making
the back of the catch in the form of an inclined flat surface which when the driver
is moving backwards would push any pin out of its path.
The slot and circular indicators described are typical of the manner in which
our invention may be carried out, but we may employ modifications of the means
herein before described for indicating the positions of the tongues.
The transmitter described in connection with our circular indicator may be used

page_text: in connection with our slot indicator, but in such cases the latter must be provided
with means for locking the movements as soon as the current is cut off, in order
to prevent the tongues from being accidentally reversed by mechanical vibration
or otherwise. A simple lock for the purpose is made by arranging two long rods
one on each side of the tongues. Each rod carries as many hooks as there are
tongues, each hook being adapted to catch on the corresponding tongue. The
rods are capable of a limited motion in a direction parallel to the slot in the
dial and in its normal position the hooks on one rod engage all the tongues on
that side while those on the other, side are engaged by the hooks on the other
rod. As soon as the current is switched on an electro-magnet acting on an
armature attached to the two rods moves the rods until their hooks are clear of
the tongues. When the current ceases, a spring attached to the rods restores
them to their normal position, once more locking the tongues.
When the differential movements have iron cores, for example when they are
made like the well-known Siemens polarized relay, the coercive force of the iron
cores necessitates a larger reversing magnetising force. This increases the
power wasted in the windings and so reduces the number of movements that can
be safely worked in series without overheating. For this reason we prefer to
dispense with iron cores when a large number of signals is required. On the
other hand when there are only a comparatively small number of movements in
series, as for example in the above described indicator having two or more slots
for showing numerals by units tens hundreds and so on, or as in a circular
indicator adapted for an engine room telegraph, the use of iron cores is advan-
tageous as their coercive force serves to hold the tongues securely against their
stops when the current is cut off and thus dispenses with the need for any further
locking device.
Dated this Twelfth day of June 1890
:
EVERSHED & VIGNOLES, LIMITED,
ERNEST B. VIGNOLES,
Managing Director.
SYDNEY EVERSHED.
Improvements in Electric Telegraphs for Ships and other Purposes.
We, EVERSHED AND VIGNOLES LIMITED, of Woodfield Works, Harrow Road,
London, W., Electrical Engineers, and SYDNEY EVERSHED, of the same address,
Electrical Engineer, 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 electrical apparatus for the transmission of pre-
arranged signals and is applicable for any purpose where a limited number, of
definite signals or orders are required to be transmitted from one position and
indicated on a dial or otherwise at any other position; and is more particularly
applicable for engine room, steering, docking and other telegraphs required on
board ship.
Our invention is based on the same principle as the telegraphic systems for
similar purposes described in the Specification of Patent No. 8784 of 1891,
namely that the signal or order shown by the indicating apparatus (hereinafter
referred to as the indicator) depends only on the ratio of the currents in two

page_text: circuits fed from a common source of E.M.F. and not on their absolute value,
so that the indications given are not affected by variations in the E.M.F. applied
in common to the said circuits and the transmitting devices (hereinafter referred
to as the transmitter) described in the said specification may, with certain modi-
fications to be presently described, be employed in carrying out our present
invention which relates more particularly to the means by which the ratio of
the currents in two circuits (hereinafter referred to as the ratio circuits and
distinguished as the A circuit and the B circuit respectively) determines the posi-
tion of the index or other indicating appliance on the dial or scale of the
indicator.
The essential parts of an indicator made in accordance with our present inven-
tion are a number of differentially wound electromagnetic devices (hereinafter
referred to as "movements") similar to the well known polarized relays commonly
used in telegraphy, but, without their contact devices. Each of these move-
ments comprises a permanent magnet or magnetised tongue (hereinafter referred
to as a tongue), fixed on, and at right angles to an axle and capable of limited
angular rotation between two stops (hereinafter referred to as the positive and
negative stops respectively. The tongue moves in the magnetic field of a
differentially wound coil which may contain an iron core or cores. The two
windings of the coil (hereinafter called the. A winding and B winding of the
movement) are connected respectively to the two ratio circuits and the ratio
currents being caused to flow through the two coils in opposite senses the direc-
tion of the resultant magnetic field will depend on the relative strength of the
magnetising forces of the two windings, and the tongue will rest against one
stop or the other according to the direction of the said resultant field.
A simple form of indicator may be made by arranging a number of such
movements in a row behind a longitudinal slot in a dial. Each movement
carries a light shutter on a rod extending radially from and attached to its axle
and the shutter is curved so as to form part of a cylinder of large radius con-
centric with the said axle. The movements are so fixed with relation to the
dial as to cause their shutters to take up positions side by side immediately
behind the slot, the whole series of shutters forming an almost continuous and
nearly flat surface, the axles of the movements being arranged in line with
each other and parallel to the length of the slot. Each shutter has one half of
its surface painted black and the other half white so that either the black or the
white portion is visible through the slot in the dial according to whether the
tongue is resting against the positive or negative stop.
With this type of indicator the number of movements is equal to the required
number of signals. The signals are marked on the front of the dial in succes-
sion beside the slot: for example, if the signals are a series of numbers, the
figures will begin with zero at one end of the slot and end with the maximum
required figure at the other end of the slot.
:
The movement coils are connected so that all the A windings are in series
with each other and with the A circuit, and all the B windings are similarly
connected in series with the B circuit. The number of turns of wire on the
coils of each movement is determined by means of the following definite and
simple law that is to say, supposing a current of suitable value requires to be
reversed through T turns of wire in order to move a tongue from the positive
stop to the negative stop, the A winding of the first movement must have T
turns of wire, that of the second movement will have 2×T turns, of the third 3×T
turns and so on up to the last or Nth movement which will have N x T turns of
wire on the A winding. The B windings follow a reciprocal law, that is to
say, there are NXT turns on the B winding of the first movement, (N-1)×T
turns in the next, and so on up to the last movement which will have T turns
in its B winding.
With this arrangement of windings any number of successive movements can
be made to show the black portions of their shutters through the slot in the dial

page_text: and the remainder their white portions by suitably regulating the ratio of the
currents in the A and B circuits. For example, when the A current is equal to
the B current it is evident that in one half of the total number of movements,
namely from the movement at one end of the slot up to the centre of the
length of the slot, the B winding will predominate and cause the black portions
of the shutters to appear through the slot, while in the remaining half of the
movements of which the indicator is composed the white portions of the shutters
will be visible.
If now the ratio of the B current to the A current is increased the tongues
which are resting against the negative stops and therefore showing the white
portions of their shutters will reverse one after another, beginning with the
one next the last tongue which is resting against its positive stop.
On the other hand if the ratio of the B current to the A current is diminished
there are similar successive disappearances of the black portions of the shutters.
Thus the length of slot appears to be partly black and partly white and the
black part appears to advance and recede along the slot as the ratio of the B
to the A current is increased or diminished; and the signals are read much in
the same manner as the temperature is read on an ordinary mercury thermometer
by the position of the end of the thread of mercury on the scale."
When the signals to be transmitted are numerals we may have two or more
slots in the dial of the indicator, and provide each slot with ten movements.
The first slot will then serve to indicate the digit in the units place of any
required numeral, the second slot will indicate the digit in the tens place and
a third slot will indicate the digit in the hundreds place and so on, so that a
two slot indicator will show any numeral from 1 to 100, a three slot indicator
will show any numeral from 1 to 1000 and so on.
The series of movements belonging to each slot will he connected to a separate
ratio circuit controlled by a separate multiple point switch and resistances in
the transmitter, so that there will be as many independent ratio circuits as there
are slots. These ratio circuits may either be coupled in series or in parallel with
cach other, and the multiple point switches may be coupled mechanically to-
gether if it is desired to make all possible signals by means of a single handle
on the transmitter.
"
Indicators of the type described above may be and are herein called "slot
indicators to distinguish them from a modification in which the series of
differential movements is made to control the position of an index on a circular
dial, a type of indicator which may be and is hereinafter called a circular
indicator."
66
In one form of our circular indicator the movements are arranged symmetri-
cally and equally spaced round a circle, (hereinafter referred to as the " move-
ment circle"), having its centre on the axial line passing through the index
axle and its plane parallel to that of the dial and a suitable distance behind it.
The rotational axis of the axle of each movement is a tangent to the said circle
so that the tongues are free to move in planes radial to the axis of the index
axle. A pin or rod of suitable length is attached to and moves with the axle of
cach movement, its motion being limited by suitable positive and negative stops
as in the slot indicator. These movement pins project inwards towards the said
axial line and their ends lie on one or other of two circles (concentric to the
said axial line and parallel to each other) according to whether the correspond-
ing tongues are against the positive or the negative stops. These two circles
are hereinafter referred to as the positive and negative pin circles. The move-
ment circle and the pin circles are of course only imaginary lines by which the
positions of the movements and their pins are conveniently specified. The pin
circles as described are necessarily smaller in diameter than the movement circle
and they are symmetrically disposed on each side of the plane of the movement
circle.
The necessary relation between the positions of the pins and that of the index

page_text: on the dial is established by means of an electromagnetic mechanism herein-
after referred to as the "Driver Mechanism."
It consists of an inner axle (in line with the index axle but not attached
thereto) carrying at one end a radial arm adapted to rotate in the plane of the
positive pin circle and having a plate or catch at its outer end adapted to impinge
on any movement pin which may be in the said plane.
A sleeve on the inner axle and capable of rotating freely thereon carries a second
and similar arm adapted to rotate in the plane of the negative pin circle and
impinge on any movement pin which may be in the plane of the said negative
pin circle. The inner axle and the sleeve are connected together by means of a
coiled spring which is always in torsion so that the two arms tend to rotate in
opposite senses.
These two arms may be and are herein called "drivers and they are dis-
tinguished as the positive driver and the negative driver because they rotate
respectively in the plane of the positive and negative pin circles.
The action of the coiled spring causes the positive driver to rotate (missing all
the pins which are on the negative pin circle) until it comes in contact with the
first of the pins which is on the positive side. All the pins beyond this one will
be on the positive side also, so that the spring will at the same time cause the
negative driver to pass all these pins until it comes in contact with the first of
the negative pins, that is to say the one next to that with which the positive
driver is in contact. Thus the coiled spring rotates the drivers until they rest
against adjacent pins. When in this position they are not quite in the same
radial plane and a rod or crank pin projecting back from a crank arm fixed
on the index axle passes between them in a direction parallel with their common
rotational axis. Since the crank pin cannot pass the drivers its angular position
with respect to its rotational axis and consequently the position of the index on
the dial will be governed by and depend upon the position of the two drivers
when they are resting against the movement pins.
The inner axle is connected by suitable gearing with the armature of an electro-
magnet hereinafter referred to as the "driver magnet." The sleeve on the inner
axle is similarly connected to a second and independent armature adapted to be
attracted by the driver magnet. When the driver magnet is excited its attraction
on the two armatures opposes and overcomes the torsion of the coiled spring so
that the two drivers fly rapidly backwards until they are beyond the first and last
movement pins, here they each come in contact with suitable stops against
which they rest so long as the "driver magnet" is excited. When the drivers
are so resting against the stops the movement pins are free to take up their
positions against the positive or negative stops according to the ratio of the
currents in the A and B circuits.
The windings of the movements are arranged according to the law already
described in connection with our slot indicator and the position of the movement
pins is therefore governed by the ratio of the B current to the A current in the
same manner also. The driver magnet winding is in the return circuit so that the
sum of the A and B currents traverses its coil.
Our circular indicator only requires the current to be on while a signal is being
made, and we therefore modify the transmitter described in Patent No. 8784
of 1891, by providing it with a switch so connected with the transmitter handle
that it is impossible to move the latter without first closing the switch and as
soon as the handle is brought to the desired signal the switch is released and
automatically opens the circuit and at the same time locks the handle in place.
When it is desired to indicate a new signal or order on the indicator dial, the
switch is first closed thereby unlocking the handle and at the same time causing
the current to flow through the ratio circuits and thence through the winding of
the driver magnet. The attraction of the driver magnet armatures causes the
drivers to fly back against their two stops clear of the movement pins. The
transmitter handle being then moved over the contacts towards the one which

page_text: corresponds with the desired signal, successive tongues in the indicator reverse
as the transmitter handle passes over successive contacts. When the handle is
brought to the contact corresponding to the desired signal it is locked there by
opening the switch and the current being thereby stopped the driver magnet
ceases to be excited and its armature cease to be attracted. The coiled spring
thereupon causes the drivers to fly forward until they again rest against adjacent
movement pins, the particular two depending of course on the ratio of the
B current to the A current at the instant when the switch was opened. The
crank pin being between the two drivers is forced by their movement into the
new position they have now taken up and the index consequently points to the
desired signal.
By observing suitable proportions between the forces acting on the drivers and
the moment of inertia of the moving parts of the driver mechanism, the time
occupied by the drivers in moving backwards from the movement pins to the
driver stops, may be made so short that it is quite impossible for the transmitter
handle to be moved by hand from one contact to the next before the drivers
have reached the stops and consequently the drivers are always quite clear of the
movement pins before any of the tongues reverse their positions. As an additional
precaution to ensure certainty of action the plates or catches at the ends of the
drivers may be so shaped on one side that they cannot when moving back-
wards catch on any movement pin which might accidentally be on the wrong
circle. This is readily effected by making the catch in the form of a hook or
V notch on its forward side so as to catch and lock the pin against which it
impinges when the current is cut off, and by making the back of the catch in the
form of an inclined flat surface which when the driver is moving backwards
would push any pin out of its path.
The slot and the circular indicators described are typical of the manner in
which our invention may be carried out, but we may employ modifications of the
means hereinbefore described for indicating the positions of the tongues.
The transmitter described in connection with our circular indicator may be
used in connection with our slot indicator, but in such case the latter must be
provided with means for locking the movements as soon as the current is cut off,
in order to prevent the tongues from being accidentally reversed by mechanical
vibration or otherwise. A simple lock for the purpose is made by arranging two
long rods, one on each side of the tongues. Each rod carries as many hooks as
there are tongues each hook being adapted to catch on the corresponding tongue.
The rods are capable of a limited motion in a direction parallel to the slot in
the dial and in its normal position the hooks on one rod engage all the tongues on
that side while those on the other side are engaged by the hooks on the other rod.
As soon as the current is switched on, an electro-magnet acting on an armature
attached to the two rods, moves the rods until their hooks are clear of the
tongues. When the current ceases, a spring attached to the rods restores them to
their normal position, once more locking the tongues.
When the differential movements have iron cores, for example when they are
made like the well known Siemens polarized relay, the coercive force of the iron
cores necessitates a larger reversing magnetising force. This increases the power
wasted in the windings and so reduces the number of movements that can be safely
worked in series without over heating. For this reason we prefer to dispense
with iron cores when a large number of signals is required. On the other hand
when there are only a comparatively small number of movements in series, as for
example in the above described indicator having two or more slots for showing
numerals by units, tens, hundreds and so on, or as in a circular indicator adapted
for an engine room telegraph, the use of iron cores is advantageous as their
coercive force serves to hold the tongues securely against their stops when the
current is cut off and thus dispenses with the need for any further locking device.
In order that our invention may be better understood we will now describe it
with reference to the accompanying drawings.

page_text: Figure 1 shows a form of polarised movement well adapted for the purposes of
our invention.
Figure 2 is a diagram illustrating the electrical principle of our invention, and
Figure 3, a modified arrangement of resistances and connections in our
transmitter.
Figure 4 shows the general arrangement of the dial and shutters of our slot
indicator.
Figure 5 shows in perspective the working parts of our dial indicator, and
Figure 6 shows the means we adopt in our transmitter when it is desired to cut
off the current after making a signal.
The
In Figure 1, a tongue of iron n.attached to an axle a is pivotted in a recess
in the pole of a permanent magnet N, S, and adapted to move between or near
the soft iron pole pieces fl and f which are attached to the core C.
position of n depends on the polarity of f¹ and f A rod R fixed on the
tongue axle is arranged to move between two adjustable stops J¹ and J. The
rod R serves to carry a shutter in our slot indicator or it serves as the movement
pin in our dial indicator. The core passes through a bobbin divided into two
portions by an insulating disc d, one portion A being wound with one or more
sections of the A circuit and the other portion B with one or more sections of the
B circuit, the position of the disc d depending on the place the movement occupies
in the series of movements forming our indicator. The form of movement shown
in Figure 1 is a modification of the polarised movement used in the well known
Siemens telegraph relay.
Figure 2 shows the manner in which a number of polarised movements may
be connected in series in order to give an indication of the ratio of the Å
and B currents. Six movements are shown as embodied in the indicator I, but
any number more or less may be employed according to the number of signals
required to be shown. C¹ to C represent the soft iron cores of six polarised
movements and each core is shown surrounded by seven turns of wire, each turn
representing a unit section of winding; that is to say, the diagram shows one
turn of wire per section whereas in actual practice there will be many turns per
section, but no matter how many turns there may be, every section contains the
same number. T shows the transmitter; K, being a sliding contact which can
be moved by the transmitter handle over the fixed contact blocks numbered 0
to 6. In the position shown in the diagram, K makes contact with block No. 3 80
that the current from the battery E divides equally; one half passing through
the resistances and into the A circuit and the other half through the
resistances 5 and 6 into the B circuit. When the total current is equally
divided in this way it is evident that in the windings round C¹ C and C³, the B
current will predominate and these three cores will consequently be magnetised
in the direction indicated by the letters S. Similarly the cores C4 C5 and C
will be magnetised in the reverse direction as indicated by the letters N. The
resistances to 6 are so adjusted that on moving K from contact No. 3 to
contact No. 4 (which strengthens the B current and weakens the A current) the
polarity of C will be reversed. At the same time C₁ C and C³ have their
magnetism strengthened but their polarity, on which the indications depend,
will not be altered.
:
Similarly C and C will have their magnetism weakened by the movement
of K but their polarity will remain unaltered.
On moving K on to contact 5 the core C³ will reverse its polarity, and so on
with other contacts and cores.
The value to be given to each of the resistance coils 1 to 5 is determined in
a simple manner. If the resistance of all the A coils a¹ to a when coupled in
series is called X then each of the resistances 1 to 6 must be equal to twice X.
It will be obvious that with the scheme of winding shown on the cores the
resistances of all the B coils in series will be the same as that of all the A coils
in series; hence another way of stating the rule for finding the value of the

page_text: transmitter resistances is to say that each resistance coil is to be equal to the
resistance of all the A coils plus the resistance of all the B coils in series.
After the ratio currents have done their work in the movements the two
circuits A and B are brought together and connected by a common return wire R
to the battery E. It is to be noticed that as the transmitter contact moves
towards one end or other of the series of contact blocks the total current pro-
ceeding from the battery increases reaching a maximum when K is on contact 6
or contact 0. This may lead to an undue heating of the movement coils due
to the electrical power spent in them, and to obviate this we prefer to employ
auxiliary resistances Y and Z in our transmitter. The function of each of these
resistances is to add a resistance to the return circuit R as K is moved towards
either end of the row of contacts, sufficient in amount to keep the total current
proceeding from the battery as nearly constant as possible. The value of Y
and Z is easily determined by experiment, no very exact adjustment being
required so long as the current does not vary beyond the limits imposed by the
heating of the movement coils.
The
In Figure 3 we show a modified arrangement of resistance coils for our trans-
mitter. In this modified arrangement each ratio circuit has its own series of
resistances; thus the A circuit is connected to a number of resistance coils p¹
to p, and the B circuit to an exactly similar set of resistances q¹ to 9.
several resistance coils on the A side are not all alike nor are those on the B
side alike in value, but q' has the same value as p¹, q as p³ and so on, and the
value of each of these resistances is determined by the following rule.
If the total number of resistance coils in the A side is N and the total resist-
ance of all the A coils on the movements is X (as before) then the nth resistance
1 1
or the rule may be stated thus: add half X to the product of X into N and
divide the sum by the square of n diminished by a quarter; the resulting figure
will be the value to be given to the nth resistance coil.
Having found the value of each of the resistances on the A side an exactly
similar series of resistances is to be used for the B side, for as already stated the two
sides are exactly alike. With this modified arrangement of resistances the total
current proceeding from the battery remains constant throughout the whole
range of positions which K can occupy and the modification has the further
advantage that it greatly reduces the total electrical power employed so that it
is quite possible by the use of this modified transmitter to arrange our telegraph
to be worked by a primary battery of moderate size, provided the arrangement
already referred to and to be presently described, for cutting off the current when
the signal is made, is adopted. On the other hand the arrangement of trans-
mitter shown in Figure 2 has the advantage of simplicity of parts and when
the telegraph is to be worked by means of a current drawn from a dynamo the
total power spent in working the apparatus is not a matter of consequence.
In Figure 4 we show the manner in which we arrange a number of polarised
The movements, of
movements to form the slot indicator already described.
which we show 10 in number, are arranged one above the other with their axles
in line with one another as indicated by the line W W. To avoid confusion all
details of the movements are omitted with the exception of the axles, the mag-
netised tongues n¹ to n¹0 and the rods 1 to 10. Each rod carries a light shutter
having a cylindrical surface concentric with W W. One half of each shutter w
or other
is painted white and the other half y is painted black
shutters пе fix a
distinctive colours. Immediately in front of the
the white ог
.black portions of the shutters are visible. Now it will be obvious that whether
the white or black portion of any particular shutter is visible will depend, on
dial D having a slot or slots in it through which

page_text: the polarity of the core of the movement to which that shutter belongs, and
as we have already explained, the movements in which the B winding predomi-
nates will show the black portions of their shutters through the slot. Hence
referring again to Figure 2, if the sliding contact were moved to block 6 all the
shutters in the indicator would show black while if it is moved on to the contact
block 0 all the shutters will show white. In the position shown in Figure 4
six of the shutters show black, and the remainder white, that is to say in six
out of the ten movements composing the indicator shown, the B current pre-
dominates and in the remainder the A current. The manner in which the slot
indicator can be made to indicate numerals is clearly shown in Figure 4. And
one or more additional slots may be provided and behind each slot a series of
movements, thus enabling the first slot to indicate units, the next tens, the next
hundreds, and so on. Each slot and its series of movements must be connected
to its own series of resistances in the transmitter and the several sets of move-
ments and resistances may either be separately supplied with current or they
may all be connected in series with one another so that the same current
traverses them in succession.
We do not confine ourselves to showing figures in our slot indicator; it is
obvious that any letters, words, or other signs may be substituted for the
numerals shown in Figure 4.
In Figure 5 the tongues a of the polarised movements are arranged in a
circle or part of a circle round the axial line L L their axles being tangential
to a circle P which is what we have defined as the movement circle. The move-
ment pins 1 to 8 extend inwards towards the axial line and their ends lie upon
one or other of the two pin circles P1, P2, P₁ being what we have called the
positive pin circle and P2 the negative pin circle. The differential movements
being wound in the manner already described the position of the movement
pins depends on whether the A or B winding predominates; thus all those
movements in which the A current predominates will have their pins resting
upon the circle P¹. In Figure 5 the A current is supposed to predominate
in all the movements from the first to the sixth and consequently pins Nos. 1
to 6 are shown with their ends lying upon the circle P' while in the remaining
two movements the B current is supposed to predominate and hence the ends
of their movement pins Nos. 7 and 8 are resting upon the circle P². As
already explained the circles P¹ P2 and P are imaginary lines and merely
intended to enable the positions of the movements and their pins to be clearly
defined and easily understood.
The position of the index I upon the telegraph dial is controlled in the
following manner:-Fixed upon an axle is a radial arm D' upon the outer
end of which is fixed a catch m¹. A similar arm D2 and catch m³ are fixed upon
the outer axle or sleeve a surrounding a¹. In the annular space between a³
and a a spiral spring is coiled having one end fixed to a¹ and the other end
to a². An initial torsion is given to the spring which tends to rotate «³, 12
and m² in a clockwise direction and a¹, D' and m! in the opposite sense.
rotates until its motion is arrested by the notch shown in the end of m² catching
Hence a²
upon the first movement pin which may be on the circle P2 that is to say when the
movement pins are in the positions shown as an example in Figure 5, m² catches
on pin 7, similarly m¹ is caught on pin 6. The length and disposition of the
catches is such that when they are caught against adjacent pins as shown, the
two arms D1 and D2 are not quite in the same radial plane, this disposition being
made in order that a cranked rod extending back from the index axle A may
pass between the arms D and D. In this way so long as the catches remain
against adjacent pins the rod r is unable to move in either direction; hence the
index I is firmly held in a position corresponding with the position of the
catches. The axle and sleeve, the spiral spring connecting them, and the two
arms and catches form what we have herein before referred to as the driver
mechanism, D' and m¹ being the positive driver; D³ and m³ the negative driver.

page_text: When a fresh signal is to be made the catches must be rotated until they
are out of the way of all the movement pins so that the latter may be free to
take up new positions corresponding to the desired signal. This motion is
effected by means of the magnet M which is connected in the return circuit R
(Figure 2) of the telegraph so that it is traversed by the whole current. This
magnet becomes magnetised as soon as the current is automatically started
previous to making a signal (in the manner already referred to and hereinafter
to be more particularly described) and attracts its two armatures K' and K³ which
are adapted to be drawn in between the pole pieces p p. K is geared by means
of a toothed sector s to a pinion g¹ fixed upon the positive driver axle a¹, simi-
larly K is geared through the segment to a pinion which is fixed upon the
sleeve or negative axle a. The counter-clockwise rotation of K₁ rotates a¹ and
the positive driver arm and catch D¹ and m¹ in a clockwise direction until the
back of the catch abuts on a stop h¹. Similarly the clockwise motion of K
carries the negative driver and catch D2 and m³ back until the catch abuts
on the stop .
These motions are of course opposed by the torsion of the spring already
referred to and the strength of the magnet must be such as to not only easily
overcome the torsion of the spring but cause the backward motions of the two
drivers to take place within a small fraction of a second of time. By adopting
a magnet of the type shown the armatures can be made to balance the weight
of the toothed segments and the moment of inertia of the whole moving system
can be made sufficiently small to secure the desired rapidity of motion.
"
$6
The transmitter handle may consequently be moved to a fresh signal as quickly
as possible after the current has been started without any risk of changing
the positions of any of the movement pins before the catches have had time
to travel backwards into the position where they rest clear of the path of all
the pins. As the transmitter handle is moved over the dial from signal to
signal altering the ratio of the A and B currents step by step as the contact
travels over the contact blocks, the corresponding movement pins reverse their
positions in succession. For example, if the index is moved from the signal
Slow ahead" in Figure 5 to the signal Stop," movement pin 6 will reverse
its position as the transmitter handle passes from "Slow" to the next signal
Stand by," and movement pin 5 will reverse its position as the handle passes
Stand by" to Stop." The act of locking the transmitter handle in the
position chosen hereinafter described breaks the circuit; the attraction of the
magnet M upon the armatures K¹ and K³ ceases, thus allowing the torsion of
the driver spring to act; driver D¹ immediately moves away from h¹ in a counter-
clockwise direction impinges on the rod r and carries it before it until the catch m
comes in contact with pin 4 which is now the first pin to be met with on the
positive pin circle. Concurrently with this action the driver Ds leaves the stop h
and rotates in a clockwise direction until it is stopped by coming in contact with
pin 5 which is now resting on the negative pin circle. The rod r will then have
been rotated through an angle equal to that occupied by two movements and the
index I will have come to rest at the signal "Stop."
from
*
.
In the intervals between the making of different signals, by moving the
transmitter handle, the current is cut off and consequently the movement pins
and tongues are not (with two exceptions) held firmly against their stops, the
two exceptions being of course the two pins against which the catches are resting,
these two being prevented from moving by the notches in the catches. When
the differential movement contains an iron magnetic circuit such as that shown
in Figure 1 the coercive force of the core and pole pieces provides a sufficient
force to prevent the tongue from leaving the stop with which it happened to
be in contact at the moment when the current was last cut off so that the movement
pins have no tendency to leave their positions on the pin circles unless they are
forced to do so by a change in the ratio of the A and B currents; but it is obvious
that if a pin (for example pin 8 in Figure 5) were by some accident to be brought

page_text: 60
away from circle P* on to circle P¹ then the next time the transmitter handle was
unlocked and the current turned on the driver D¹ on rotating clockwise towards h¹
would foul pin 8 and be unable to reach the stop. To avoid this we cut off
the back end of each catch in a direction inclined to the direction of
motion that driver D₁ in the above example would push pin 8
out of its path and come to rest in the proper manner against h¹. This precaution
ensures the drivers being able to travel backwards to the proper extent as soon as
the current is switched on, no matter what positions the movement pins may
occupy owing to accidental circumstances. As soon as the current has reached
its normal strength the movement pins of course occupy their proper positions
controlled entirely by the ratio of the A and B currents.
It will be noticed that when the signal "full ahead or 'full astern" is to be
shown all the pins from 1 to 8 will be on the positive or negative pin circles,
hence one more pin is required at each end of the series of movements. The
stops h¹ and hs are adapted to serve this purpose and on making a signal "full
speed ahead for example, all the movement pins will rest upon the positive pin
circle 1. Driver D¹ will rest against pin 8 and driver D₁ will rest with its
notched end against h³.
"
As already stated our circular indicator requires a modified form of trans-
mitter arranged to automatically cut off the current as soon as its handle has
been locked at the position corresponding to any signal. A form of transmitter
handle suitable for the purpose is shown in Figure 6. The contact blocks M¹
are attached to a circular insulating ring V the sliding contact K is fixed by
means of an insulating sleeve upon the transmitter axle a³; a ring pieces is
mounted upon the same insulating sleeve and makes a rubbing contact with Q
to which the return circuit R of the telegraph system is connected. The trans-
mitter handle H is fitted with a latch J, one arm of it is adapted to drop into
a series of notches in a fixed ring G so that the handle can not be moved until
the latch arm has been withdrawn from the notch. A connecting rod between
the latch arm and a switch pivotted on s ensures the closing of the circuit at t
before the latch arm has been completely withdrawn from the notch so that K
is put into electrical communication with R immediately before the handle is
unlocked, and conversely the locking of the handle in any notch breaks the
current at t.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we declare that what
we claim is:-
1. An electric telegraph, comprising in combination, a number of polarised
movements, adapted to respond to a series of predetermined ratios of the currents
in their differential windings, means for showing the polarity of the said move-
ments as an indicator; and a series of resistance coils controlled by a multiple
point switch as a transmitter, substantially as described.
2. In an electric telegraph, an indicator, comprising, in combination, a number
of polarised movements, adapted to respond to a series of predetermined ratios
of the currents in their differential windings; and shutters behind slots in a
dial operated by. the polarised tongues of the said movements according to their
polarity substantially as described with reference to Figure 4.
3. In an electric telegraph an indicator, comprising, in combination, a number
of polarised movements adapted to respond to a series of predetermined ratios
of the currents in their differential windings, and mechanism adapted to control
the position of an index on a dial in accordance with the polarity of the said
movements, substantially as described with reference to Figure 5.
4. In combination in an electric telegraph, a series of polarised movements
responding to differential windings, having means for indicating said move-
ments; a duplicate series of resistance coils; and a multiple point switch-gear

page_text: controlling same as a transmitter; the whole adapted to keep the total current
constant, while varying the ratio of the two portions into which the said current
is divided by the said switch gear, for the purposes substantially as set forth and
described with reference to Figure 3.
Data thin 10th dant A 1000
FELL & JAMES,
1, Queen Victoria Street, London, E.C..
Agents for the Applicants.