Improvements relating to the Transmission of Signals Through Submarine Telegraph Cables.
Year: 1894

page_text: Date of Application, 16th Mar., 1894
Complete Specification Left, 15th Jan., 1895-Accepted, 23rd Feb., 1895
PROVISIONAL SPECIFICATION.
Improvements relating to the Transmission of Signals Through
Submarine Telegraph Cables.
I, ALEXANDER MUIRHEAD, of No. 2 Princes Street, in the City of
Westminster, Doctor of Science, Electrical Engineer, do hereby declare the
nature of this invention to be as follows:-
This invention has reference to the automatic transmission of telegraphic
Bignals on submarine cable circuits and has for its object to increase the efficiency
of the contact-making devices involved in such a mode of transmission, and to
provide improved means of effectively applying curbing currents in connection
with such system:
According to my invention the two contact-making or contact-breaking levers
of the automatic transmitter are, at their ends which enter the perforations of the
punched paper strip, each formed with steel noses one edge of which is flat while
the other is curved or rounded off similar to the tooth of a ratchet wheel. The
advantage of this formation of the noses is that upon a perforation in the paper
strip coming opposite to one or other of them, such nose enters the perforation
quickly by its flat side and leaves it slowly by its curved side. The effect of this
is that the delay in the breaking of contacts due to the unbending of the spring at
the other end of the lever on its limiting stop as the lever falls into the
perforation is compensated for by the slow return of the lever to its limiting stop.
This slow return of the levers to their position of rest prevents all "jar" at the
contact ends of such levers.
On either side of, and on the same spindle as, the spur-wheel which carries
along the perforated paper strip are fixed two rollers, having as many grooves in
them as there are spurs or teeth in the spur-wheel. These rollers keep the paper
strip taut as it passes underneath them and they assist in driving or pushing' the
noses of the levers out of the perforations as the paper strip is carried along by
the central row of spurs in the spur-wheel. Alternatively I may attach cams to the
mechanism and adjust them relatively to the spur-wheel so that they come into
contact with the levers of the automatic transmitter at the moment when the noses
of the levers should be on the point of leaving the perforations in the paper slip.
On the same spindle as the spur-wheel and the two grooved rollers hereinbefore
referred to are fixed two contact-making wheels each having as many breaks in the
continuity of its periphery as there are teeth in the spur-wheel or grooves in the
grooved rollers. These contact-wheels are adjusted relatively to the spur-wheel
so that whenever one or other of the levers of the apparatus falls into a perfora-
tion in the paper strip the corresponding part of the circumference of the contact
wheel comes into contact with the spring or roiler resting on it. The circuit
between the said levers and the battery is completed through these contact-
wheels.
In order to transmit "curb" currents, two extra wheels of similar construction
to those lastly hereinbefore described are fixed alongside them. The periphery of
each of these extra wheels is built up of a number of alternate conducting and
insulating portions of triangular shape dovetailing into one another so that the
length of contact between the wheels and the spring contacts which rest on them
can be regulated by varying the position of the springs laterally by means of a
tangent screw or equivalent device

page_text: :
Sometimes I may mount the last-mentioned contact-wheels on a separate spindle
and gear them to the spur-wheel so that they revolve once for every space in the
perforated paper strip.
When it is desired to transmit the signalling currents directly into the cable
from the automatic transmitter without the intermediary of a local electromagnetic
transmitter the contact-wheels may be designed to make both the battery and the
earth contacts with the cable and are adjusted so that the spaces on their
circumference between the battery and the earth parts of the circumference will
pass under the contact springs just when the centres of the side perforations of the
paper strip pass under the noses of the levers. The relative lengths of the
signalling currents and the earthing period depend upon the relative lengths of
the part of the circumference of the contact-wheels connected to battery and
earth respectively.
When the levers of the automatic transmitter are employed to complete the
circuit of the local electromagnets with the battery and adjustable electromagnetic
shunt is applied to the coils of the local electromagnets in order to prolong the
attraction of the armatures of the latter to the desired amount. The coils of the
local electromagnetic transmitter are preferably wound differentially and connected
to the levers of the automatic transmitter in such manner that the current flows
through them in the opposite direction when no perforations of the paper strip pass
the ends of the levers. On the other hand whenever a perforation passes the
end of one of the levers the circuit of one coil is broken and the current from the
local battery only flows through the other coil. This arrangement of the coils of
the transmitter reduces the sparking on making and breaking the circuit of the
local battery to a minimum.
The punchers I prefer to employ for perforating the paper strip are the same as
those used in the well-known Wheatstone system of automatic transmission on land
lines with the slight alterations necessary to adapt them to the submarine cable
mode of signalling. The perforations for this invention are preferably made oblong
and punched transversely to the length of the paper strip in order to permit of
greater lateral play in the contact levers of the automatic transmitter.
Sometimes the limiting stops on which the levers of the automatic transmitter
fall whenever a hole or perforation passes their respective noses may be made to
revolve at a uniform speed and in constant relationship with the spur-wheel which
carries the paper strip along, for the purpose of securing better contacts between
the levers and the poles of the battery employed. These constantly revolving
studs or limiting stops may be constructed in the same manner as the revolving
contact-wheels above described so that in the ordinary mode of signalling the
battery and earth contact may be successively made.
In some cases I may attach armatures to the levers of the automatic transmitter
and place electromagnets beneath them joining the coils of the electromagnets to
the lower limiting stops of the automatic transmitter in such manner that whenever
one or other of the levers falls on its respective limiting stop a current is set up in
the corresponding electromagnet the result being that the armature is attracted
and the lever to which it is attached withdrawn from the perforation in the paper
strip. This device is for the purpose of assisting the paper strip to drive or push the
noses of the automatic transmitter levers out of the perforations of the paper and
thereby to secure a greater regularity of working.
Sometimes may prefer to send the "curbing" currents into the line direct from
the armatures of the non-polarized transmitter. A double polarized transmitter
is placed in the local circuit of the non-polarized transmitter in such manner that
the tongues of the double-polarized transmitter are joined up in series with the
contact-levers of the autoniatic transmitter and across the terminals of the coils of
the non-polarized transmitter. In circuit with the coils of the double-polarized
transmitter two condensers are placed and so joined up with the levers of the
automatic transmitter that whenever one or other of the latter is depressed on the
passage of a perforation in the paper strip under the nose of the lever, a current

page_text: from the local battery flows through the corresponding electromagnet attracting its
armature and connecting one pole of the battery to line and the other to earth.
At the same time the corresponding condenser is charged through the coils of the
double-polarized transmitter which are in connection with the opposite levers.
This charging current is in such direction as not to open the local circuit of the
opposite side. On the return of the automatic lever to its limiting stop the
lischarge from the condenser in the reverse direction through the coils of
the electromagnet in circuit therewith causes a momentary breaking of the local
circuit and consequently a current of short duration flows through the coils of the
non-polarized transmitter, the result being a current from the opposite pole of the
hattery into the line, that is to say, a curbing current. The amount and duration
of this curbing current can be regulated by varying the capacity of the condensers
and resistances placed in series with them or as shunts to them.
Dated this 16th day of March 1894.
A. F. SPOONER,
124, Chancery Lane, W.C., Agent for the Applicant.
COMPLETE SPECIFICATION.
о
Improvements relating to the Transmission of Signals Through
Submarine Telegraph Cables.
I, ALEXANDER MUIRHEAD, of No. 2 Princes Street, in the City of
Westminster, Doctor of Science, 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 has reference to the automatic transmission of telegraphic signals.
through submarine cables and its object is to increase the efficiency of the contact-
making devices involved in such a mode of transmission and to provide means
for effectively applying "curbing " currents in connection with such system.
In the accompanying drawings,
Figure 1 is a sectional elevation through the line 1, 2 of Figure 2 of an
automatic transmitting instrument.
Figure 2 is a part side elevation thereof with the springs
omitted.
Figures 3 and 5 are similar views to that of Figure 1 of modified forms of the
instrument.
Figures 4 and 6 are part side elevations thereof respectively.
Figures 7 and 9 are diagrams.
Figure 8 is a plan of the contact wheels.
Figure 10 shows a form of the transmitter in which a limiting stop revolves.
Figure 11 is a plan thereof, and
Figures 3*, 4*, 5* and 6* are matters of detail all hereinafter more fully
referred to.
Referring to Figures 1 and 2, the two contact-making levers are, at their ends
which enter the perforations of the paper ribbon, terminated by steel noses
shaped like the tooth of a ratchet wheel. On either side of, and on the same axle
as, the spur-wheel & which carries along the perforated paper ribbon are fixed
two rollers r, r in each of which there are as many grooves or interdentil spaces
shaped like those of a ratchet wheel (as shown clearly at in Figure 5) as there
are spurs or teeth in the spur wheel. These rollers assist the perforated paper
ribbon as it travels along in driving or pushing the noses of the levers / out of
the perforations in the paper ribbon. In some cases. these grooved rollers are
placed further apart on the axle of the spur-wheels as shown in Figure 6 to
permit of the paper ribbon passing between them and so that projections or

page_text: With
branches from the levers / may be arranged to rest on them. From the shapes.
of the grooves these branches of the levers I move quickly in and gradually out.
of the interdentil spaces as the noses a enter and leave the perforations of the
paper and these grooved rollers are accurately adjusted on the axle relatively to
the spur-wheel so that the projections begin to fall into the grooves at the
moment the holes or perforations in the paper ribbon are fairly opposite the
ends
of the levers 1. The character of the motion imparted to the levers by
the grooved rollers may be varied by altering the shape of the greoves r.
the arrangement described with reference to Figures 5 and 6 more prompt and
effective contact-making takes place when the mechanism is run at high speeds.
The spur-wheels may either be mounted on the same axle as the grooved rollers as
shown in Figure 2 or on a separate one as shown in Figures 4 and 6. In the
former case the ratchet-like grooved rollers besides assisting the motion of the
paper ribbon operate to drive or push the levers out of the perforations; in
the latter case the grooved roller gearing with the spur-wheel merely assists the
progress of the paper ribbon, the levers being driven out of the perforations by
the independent ratchet wheels r.
Sometimes instead of the hereinbefore described grooved rollers », r, wheels having
a single groove of similar shape cut in them or cams as shown at c in Figures 3 and 4
are attached to the mechanism and geared and adjusted relatively to the spur-
wheels so that they come into contact with the levers at any required moment
after the commencement of a space in the perforated paper ribbon; the duration
of the contacts of the levers with the limiting stops y', which may be connected
either to the circuit of a local transmitter or to the line battery, can thus be
regulated. The axle on which the parts are mounted is in this case geared to that
of the spur-wheels so that it revolves once during the passage of a spur of such
wheel. The parts c are so shaped, as shown in Figure 3, that the levers / can only
enter a perforation in the paper ribbon at a definite moment as with the above-
mentioned grooved rollers. Sometimes the construction of the parts c in Figure 3
is as illustrated by Figures 3* to 6*. This consists of two outside faces braced
together by the step-piece and keyed or otherwise secured to the axle c
to which motion is imparted. Located between these two outside faces is a
similarly shaped single cam disc c adjustable radially with reference to the outside
faces and suitably secured in position as for example by the screws in the slots c².
By adjusting the position of the part the length of the "step" of the cam may
be varied so that it comes into contact with the projections on the contact-making
levers at any desired moment to reset them after deflection. The noses are with
advantage replaced in these cases by upright rods jointed to the levers after the
manner of the levers in the well-known Wheatstone automatic transmitter so
that they are free to leave the perforations as the paper is carried along by
the spur-wheels before the levers are reset by contact with the said cams.
As shown in Figures 1 and 3 the levers are pivotted at the point and play
between the limiting stops y', y being pulled as shown by the spring ; they are
preferably provided with a spring contact piece for the purpose of giving a slight
rubbing contact on the limiting stop y, and in the case of Figure 3 the movements
of the rods z are limited by the stop and spring 1.
On the same axle as the spur-wheels of the transmitter or on a separate axle
geared thereto are fixed two contact wheels each having as many breaks in the
continuity of its periphery as there are teeth in the spur-wheel. These contact-
wheels are adjusted relatively to the spur-wheel so that whenever one or other of
the levers falls into a perforation in the paper ribbon the corresponding part of
the circumference of the contact-wheel coines into contact with the spring or roller
resting on it. The circuit between the said levers and the battery is completed
through these contact wheels. In order to simplify the construction of such contact
wheels 1 prefer to mount them on an independent axle geared to that of the spur-
wheels so that they revolve once for every space in the paper ribbon or on the
passage of every spur in the spur-wheel in which case there are only two breaks in

page_text: the continuity of the surface of the contact wheels. Figures 7 and 8 (Figure 7
being diagrammatic and Figure 8 a plan) illustrate the construction and arrange-
ment of the contact-wheels. The adjustable springs p which rest on the surfaces of,
the contact-wheels w are electrically conuected to the two limiting stops y' y' of the
transmitter respectively. By means of a tangent screw T Figure 8 the position of
the spring contacts p on the wheels w can be varied laterally. When it is desired
to transmit signalling currents directly into the cable from the levers of the trans-
mitter the contact-wheels are designed to make both the battery and the earth
contacts with the cable and are adjusted so that the spaces t (see Figure 7) on their.
circumference between the battery and earth parts of the circumference pass under
the contact springs at the instant the centres of the side perforations of the paper
ribbon pass the noses or ends of the levers. The duration of the signalling current
relatively to that of the earthing period depends upon the relative lengths of the
parts of the circumference of the contact-wheels connected to battery, and earth
respectively which come into contact with the contact springs resting on the wheels.
Adjustment of the position of the springs is effected in this case by means of a
tangent screw as above described. In Figure 8 the broken lines drawn parallel.
with the axis of the contact-wheels w and the lines v', ' drawn at an angle to the
axis show the breaks of continuity in the metallic or conducting surface of the
contact-wheels.
In order to transmit "curbing" currents, contact-wheels of similar construction
to those last described are fixed on the same axle as the spur-wheel s. The
periphery of each is built up of a number of alternate conducting and insulating
portions of triangular shape dovetailing into another so that the length of contact
between the wheels and the spring contacts which rest on them can be regulated by
varying the position of the springs laterally by means of a tangent screw or
equivalent device without stopping the mechanism. In order to simplify the con-
struction of these contact wheels I may mount them on a separate axle and gear
them to that of the spur-wheels so that they revolve once for every space in the
perforated paper strip as in the case of the ordinary contact wheels above described.
When the contact wheels are thus geared relatively to the spur-wheel their surface
is divided into two portions only which are connected to the battery and the contact
making levers of the transmitter through the adjustable contact spring in such
manner that the battery is reversed during every revolution of the wheels.
Figure 9 is a diagram showing the connections between the contact-wheels w and the
battery and the springs p which are connected to the levers (see Figures 1, 2, 3
and 4) of the transmitter respectively. On the revolution of these wheels the full
battery power is for the first part of every revolution put in connection with the,
contact-making levers and during the latter part of every revolution a fewer
number of cells of the battery is connected to the levers but in the reverse order..
When the full battery power is used in "curbing" a single revolving contact wheel
is sufficient, in which case the spring contacts are placed one above and the other
below the single revolving contact-wheel.
$
Sometimes the limiting stops on which the contact-making levers of the automatic
transmitter fall whenever a hole or perforation in the paper ribbon passes their
respective noses (or the upright rods jointed to them) may be made to revolve at a
uniform speed and in constant relationship with the spur-wheel which carries the
paper strip along for the purpose of securing better contacts between the contact-,
making levers and the poles of the battery employed. These constantly revolving
limiting stops may be constructed in the same manner as the revolving contact-
wheels above described so that in the ordinary mode of signalling the battery and
earth contacts may be successively made. Figures 10 and 11 (Figure 10 being
mainly in elevation and showing diagrammatically the electrical connections, and
Figure 11 being a plan of the revolving stop) illustrate the arrangement of
revolving limiting stops with the levers of an automatic transmitter made according
to this invention. y' is the limiting stop arranged in this case to revolve once for
every two spaces in the perforated paper ribbon; its surface is cut up into two

page_text: a,
sections a. A spring n is adjusted to rest continuously on y'. The contact-
springs p are mounted on a block of insulating material a³ carried on an arm 6 which
passes over the axis of y'. The arm & can be fixed in any position in the slotted
arc-piece by means of a clamp g for the purpose of adjusting the spring-contacts p
radially over y'. The springs p are shown in pairs for the purpose of ensuring
better contact but it is not necessary for them to be so constructed.
The levers
in Figure 10 are shown formed with branches kept pressed by means of springs
against the levers m which play between the fixed limiting stop y' and the revolving
oney. The jockey rollers serve to maintain the levers firmly in contact with the
limiting stops y', y² on one side or the other and the cams c³ carried on the surface
of the revolving stop y' operate to reset the levers m at the proper time after every
deflection.
When the levers of the automatic transmitter are joined up to complete the
circuit of local electromagnets with the local battery, an adjustable electromagnetic
shunt is applied to the coils of the local electromagnets in order to prolong the
attraction of the armatures of the latter to the desired amount. Such an arrange-
ment is shown in Figure 12. The coils T' of the electromagnetic transmitter are
preferably wound differentially and connected to the levers of the automatic
transmitter in the manner shown in the diagram so that the current flows through
them in opposite directions as indicated by the arrow-heads when no side perforations
of the paper ribbon pass the ends of the levers l, that is to say when the levers are
as shown in the diagram resting on the upper limiting stops. On the other hand
whenever a side perforation passes the end of one of the levers that lever leaves
the upper limiting stop, the circuit of one coil is thus broken and the whole of the
current from the local battery flows through the other coil attracting the corre-
sponding armature of the local transmitter T'. This arrangement of the coils of
the local transmitter reduces the sparking between the upper limiting stops and the
levers of the automatic transmitter on making and breaking the circuit of the
local battery B to a minimum.
In some cases I may attach armatures to the levers of Figure 10, and place
electromagnets beneath them joining the coils of the electromagnets to the limiting
stops y in such manner that whenever one or other of the levers falls on its
respective limiting stop a current is set up in the corresponding electromagnet the
result being that the armature is attracted and the lever to which it is attached
withdrawn from the perforation in the paper strip, the lever m being retained by
the jockey roller j until the cam knocks it back.
I am aware that it has before been proposed to use in automatic transmitters
contact-making levers having rounded noses in combination with rollers having
grooves of corresponding shape and I do not herein claim such, but so far as I am
aware it is new to employ noses shaped as herein described and cams or rollers
having grooves similarly shaped, that is to say like the tooth of a ratchet wheel
which shape is advantageous in that the noses fall suddenly into the interdeutil
spaces but are driven out as gradually as may be desired.
I would have it understood that the expression "contact-making levers" employed
throughout this Specification refers to the actual levers which play between the
limiting stops connected directly or indirectly to the poles of the battery and
not to any other mechanism between the perforated paper ribbon and the limiting
stops.
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
claim is :-
1. In automatic transmitters, the combination, with the spur-wheel and contact-
making levers, of rollers grooved as described mounted on the same axis as the
spur-wheel, or on an axis suitably geared thereto, for the purpose of controlling or
regulating the movements of such contact-making levers.
2. In automatic transmitters, the combination, with contact-making levers, of

page_text: cams adapted to come into contact with such contact-making levers at definite
periods for the purpose of controlling their movements.
6:
3. In automatic transmitters, the adjustable contact-wheel arrangement either
for the purpose of regulating the duration of the battery and earth contacts or for
transmitting curbing" currents during every signalling period that is to say,
during every space of the perforated paper ribbon, substantially as herein set
forth.
4. In automatic transmitters, one or more revolving limiting stops substantially
as herein set forth.
5. In automatic transmitters, the combination, with contact-making levers and
cams in connection therewith, of local electromagnets substantially as and for the
purpose herein set forth.
6. The automatic transmitting apparatus constructed, arranged and operating
substantially as herein set forth.
Dated this 15th day of January 1895.
A. F. SPOONER,
124, Chancery Lane, W.C., Agent for the Applicant.