IMPROVEMENTS IN TELEGRAPHY."
Year: 1875

page_text: LETTERS PATENT to Robert Coddington, of 88, Piccadilly, in the
County of Middlesex, for the Invention of "IMPROVEMENTS IN
TELEGRAPHY." A communication from abroad by Merritt Gally, of
Rochester, State of New York, United States of North America.
Sealed the 13th May 1875, and dated the 27th March 1875.

page_text: Fig. 2 represents the combination magnet, also showing the compound
armature.
Figs. 3, 4, and 5 are diagrams representing the main line combined
with short circuits, showing different relative arrangements of currents
to produce different effects.
Fig. 6 represents the combination key to be used either as trans-
mitter, receiver, or repeater.
Fig. 7 represents the device for securing certain movements to the
receiver by means of electric pulsations of given durations.
Fig. 8 represents the device for combined type wheel, motor, and
impression wheel when the receiver is constructed for printing the
message.
Fig. 9 represents the arrangement of connectors and plan for per-
forating when a perforating strip is used for transmission.
Fig. 10 represents a system of tripping circuits for a number of
instruments at the same station.
Fig. 11, the same as Fig. 10, having a number of instruments com-
bined with a single manipulator.
In Fig. 1 A represents a portion of the main line passing through
the connector of the magnetic switch F, from thence through the
receiver C and to ground at g.
The magnetic switch F is for breaking the line from ground through
the receiver when the key N is closed, its magnet being operated by
means of the local battery L. The operating connections in circuit D
are produced by key N, which may be substituted by any kind of a
connector, whether operated automatically or by hand. The main
battery is represented at B, and is connected from one of its poles to
main line at S. The line from its opposite pole leads to switch f. The
battery B as shown is therefore cut out, and the main line is closed to
ground to receive messages at C. The circuit D and the main line pass
through the same single wire between and 6', which wire forms the
coil of the receiving magnet. Battery L is however cut out by the
break in its circuit at key N. The main line and the receiver are thus
in the common condition for receiving messages from a distant station.

page_text: If the operator wishes not only to receive but to transmit messages
at the same time he closes the switch at f and operates key N.
Now considering the instruments and circuits of the distant station
arranged and adjusted in like manner the results will be as follows:--If
the operator wishes to throw a current through the main line from
battery B he closes key N. This operates the magnetic switch F,
breaking the direct connection of main line with ground at a, and
current from battery B passes to linc, also through the receiver to
ground. The receiver however remains inoperative as the current of
circuit D passes through the wire of the helices C in an opposite direction.
to that of the main line, and prevents the main current from magnetizing
the cores in proportion to the amount of current coming from battery L,
taking into account the comparative resistances of the two circuits, and
the comparative power of the two batteries.
It is not at all necessary that the effects of the two currents should
balance each other, and in such sense the circuit D is not necessarily
an "equating" circuit.
As so far described it is only necessary that battery L be a sufficiently
disturbing force to prevent the receiver from acting at its proper
adjustment. Were the effects of the batteries upon the magnets perfectly
in counterpoise other conditions requisite to perfect duplex action would
not be met without the use of the compensating magnetic device, which
I shall hereafter describe, referring again to the point just passed over in
describing the united action of the two circuits upon the receiving
magnet.
I will now speak of an important fact the providing for which forms
one of the principal features of the gist of my Invention, and which I
am not aware has been treated of or provided for by other electricians.
When the current of either battery B or L is passing alone through the
receiver C, it is opposed by the entire resistance of the wire in the
helices, and has a certain measurement in any point of the circuit
outside the wire contained between 6 and 7'. When the batteries and
currents are both passing in opposite directions through the helices the
currents are not in the least neutralized in the outside parts of their
circuits nor intermingled, but both remain intact with only one difference
as to their measurements. The resistance of the helices is now divided

page_text: proportionately between the two currents, and therefore each has an
increased measurement. With receiving magnets of great resistance for
long lines this increase is of considerable magnitude, and unprovided
for would naturally affect the successful duplex action of the line. For
example let the receiver be adjusted to act by means of the incoming
main line current alone, as in the first condition described, now, if
most favorably arranged and the currents of the two circuits D and A in
effect perfectly balance each other, the currents will be increased in
power when operated together in proportion to the amount of resistance
each is relieved from by their united action through the helices. The out-
going current, when the home key alone is depressed, therefore measures its
greatest power. Now, if both keys be simultaneously struck the two main
batteries will be opposed in the main line, and therefore inactive. The
local L of each station must now act upon its home receiver against the
entire resistance of the helices, making a much feebler stroke of the
armature than that of the former condition. On very long lines this
would cause breaks in very rapid or short signals, and unless provided
against would be a serious defect. I provide against such defect in the
following manner:-The receiving magnet C, as shown in Figure 2, is
provided with an additional helix and core X. The armature mis
adjusted to the stronger current which passes only through the
helices W, W. The circuit D is made first to pass through the central
helix X, and then through the helices W, W. The fainter current is
that of the circuit D when acting alone. The maguets W, W, are made
stationary and adjustment of armatures to them made only by the
spring t. The magnet X however, is in itself adjustable in respect to
the armature, and is moved nearer to or farther from it, as the case may
demand, after the adjustment of the spring is made. Now, when the
weaker current is acting upon the receiver the additional magnet X is
moved towards the armature until its added power makes the effect of the
current upon the armature just equal to the stronger current operating
only through the magnets W, W, thus the strokes of the armature lever
are perfectly equalized for all conditions. Besides this if the battery L
be comparatively light and not in any condition balancing the effect of
battery B upon the magnet C, the helix X is moved still nearer the
armature m, and the defect provided for without necessitating balancing
of batteries. If on the contrary the battery L is comparatively too
heavy the defect is provided for by withdrawing helix and core X further
from the armature, the set screw V passing through the connecting bar

page_text: of magnet W, W, is either insulated from it or is itself made of non-
magnetic metal, so that the maguctism of the cores of W, W, will not
affect the core of X.
If it be desirable to operate the armature with the current of A when
passing only in one direction for secret messages, for drop messages, or
for other purposes I make the armature of steel and harden only its
extreme ends, leaving the central portion between the dotted lines e, e,
soft. I then charge the armature with permanent magnetism. When
the ends become strongly magnetic without affecting the soft centre the
ends of armature will now act in connection with cores W, W, as a
common polarized magnet, while the magnet X with soft or polarized core
may with currents differently directed through it produce with W, W,
different effects upon armature m as the case may demand.
Diagram Fig. 3 represents the line and circuit D, as in Fig. 1; Fig. 4
shows two circuits D and D' connected with the main linc, in which the
batteries B and B arc turned as to their poles in opposite directions.
The main battery, plus to line, diminishes the magnetic effect at Z, while
it increases the magnetic effect at R, as shown by the arrows. The main
battery being reversed as to its poles produces the opposite effect, as
shown in Fig. 5.
These arrangements of circuits may be used in receiving on certain
direction of main current instead of using the polarized magnet, or for
alternating currents, or for operating different parts of clectro-mechanical
receivers, as the case may be.
If an operator at one of the keys at a station wishes to receive a
message from both directions simultaneously, or receive one and repeat
another, the key is constructed as shown in Fig. 6. The lover of the
As he is not using
key His provided with an armature n and magnet J.
his key it may now be used as receiver or repeater, and the message
coming in through A² is repeated through D.
Fig. 7 shows the device for producing certain movements in the
receiver when electro-mechanically operated, the particular movements
to be indicated by pulsations of a given length. The armature lever P
has projecting from it a spur n with V shaped point, which strikes into
the meshes of a star wheel U. To the shaft of the star wheel is also
attached a ratchet wheel as shown. To the shaft is also geared a short

page_text: train and fan Q to retard the movement of the star wheel when acted
upon by spring k and pawl Y. The pawl block slides upon the spring
rod, the rod being attached to the armature lever.
A circuit wire passes
through H to the shaft of star wheel, the points of the star connecting
with spring connector d, which carries the circuit through H.
If the receiving magnet W be operated the stroke of lever P draws
the spurn from the star wheel, at the same time drawing forward the
spring rod k. The tension of the spring is thus increased and the pawl
is driven forward, slowly and steadily moving the star wheel.
If the current through magnet W is prolonged sufficiently for an entire
mesh of the star to pass the point of spur n the wheel will be turned a
point on the return of the armature, but if the current through magnet W
is not sufficiently prolonged the spurn will force the star back to its
former position. Prolonged pulsations will therefore turn the star wheel,
shorter ones will not. Star wheels geared to different times of move-
ment may thus be made to turn by means of pulsations of different
durations. Whenever the star wheel turns a point it connects with
connector d, and operates circuit H, H', for any desired operation.
Fig. 8 represents a device for printing receiver when the line is
operated by positive and negative pulsations. Armature lever P is
worked by a polarized magnet R³. Two pawls a² on this lever are
used to turn wheel X2 the space of a single type of the type wheel T',
one pawl working with positive stroke, the other with negative. Every
stroke of the lever, either positive or negative, turns the type wheel
a single step. Every negative stroke not only turns the type wheel its
step, but also brings the paper passing over wheel Z in contact with
type wheel for the print. No time is therefore lost by an extra printing
pulsation. All the pulsations except those for the printing are positive
pulsations, but the printing pulsations also count equally on the move-
ment of type wheel with the positive pulsations. Every pulsation
passing the line, whether positive or negative, produces a single step
movement of each type wheel, so the wheels of the different stations
remain in unison without complicated unison devices.
If perforated strips are used to produce transmitting contacts of
different lengths I perforate such strip on the plan shown in Fig. 9,
and use connectors so arranged that a single perforation in the strip
will produce cither a single or double dot, or a dash, as the case may be.

page_text: The perforations are arranged in the strip in three lines. The first line
represent dashes; the second double dots; and the third single dots.
Three connectors, shown at 1, follow one after the other, connecting
through each of the first line of perforations and hold the contact for
the period of a dash. Two connectors, 2, pass through each of the
second line of perforations, but one leaves the perforation before the
other enters, so that for each perforation two dots are produced. A
single connector, 3, passes through each of the third line of perforations,
cach producing a pulsation the length of a dot. The advantage of this
plan of arrangement of perforations and connectors secures a perforated
strip with comparatively few perforations, and therefore more easily
prepared than that commonly used.
Figs. 10 and 11 represent a system of tripping circuits for a
number of instruments at the same office connected with different
telegraphic lines to be used when such instruments are operated by
automatic machinery. P², P³, P', represent different telegraphic lines
with instruments at the same station. The several instruments are
represented at Z, Z, Z, either transmitters or receivers, or both
combined.
Figs. 11 represents the instruments with a single manipulator H
for all the transmitters or receivers, or for any desirable number of them.
The circuit S¹, S¹, goes to all the instruments through S³, and to their
points of connection through S'.
It will be seen from the Figures that an operator at any one of the
instruments may connect the circuit S', S', through any other of the
instruments, or the one which he is immediately operating by making
connection at 1, 2, or 3, as the case may be, and by slipping a suitable
detent set any of the instruments in motion.
The wires 1, 2, 3, may be connected directly with the detent of their
respective instruments, and a slight movement of the wire act mechani-
cally upon the lever instead of using battery T, if so preferred. For
example, if a number of lines or branch lines come into an office I make
the circuits S', S¹, of each instrument in the office extend to other
instruments, so that an operator engaged upon one line can without
leaving his position control the transmission or receiving of messages on
other lines than the one on which he is directly operating. This
arrangement of circuits is especially important for accumulative instru-
ments if the operator have accumulative message matter in a number

page_text: of instruments for a number of lines without opportunity to transmit
any of them. While he is manipulating one instrument, if the time
signal is given for another instrument, he can without leaving the work
on which he is engaged set off the other message by the simple con-
nection of its instrument circuit S¹, S¹. He may pass from one
instrument to another, and accumulate message matter as each case
demands or his time allows, and still always be ready to transmit from
any at the proper signal without leaving his position. Instead of the
circuit S¹, S¹, a mechanical connection may be made from one instru-
ment to another; and I do not wish to limit myself in the Invention to
a mere electric connection for this purpose when connecting instruments
at a single station.
For dropping messages at way stations, or for lapping by certain sub-
terminations when messages are passing in both directions on a line
with instruments arranged on the duplex circuits represented in Fig 1,
I proceed as follows:-I first arrange the stations with two sets of
instruments. Each receiver is furnished with repeating points and h.
Now considering the instruments as those of a way station, and a
through message to be dropped, the line is brought into one set of
instruments. The wires from and h are switched into the circuit D of
the other set of instruments, and the message is passed on. The operator
at the second set of instruments may at the same time be receiving a
message from the opposite direction, and the one at the first set be
transmitting in the direction opposed to the through message. Messages
may thus be passed on through a number of stations and others sent at
the same time from intermediate to more distant stations, thus using a
single line for a large number of messages, lapping each other in different
portions of the line.
I also use the duplex circuits in connection with telegraphic printing
instruments when prolonged pulsations are not desirable for the printing
movements, as follows:--The pulsations for type wheel motors I pass in
one direction through the line, moving all the type wheels in unison, and
with opposite duplex currents produce the printing movements. For
changing the direction of the messages I reverse the order of positive
for the two distinct operations.

page_text: Tenth. The combination with the main line of subline A' and switch f
for cutting out the main battery when not in use for transmitting, sub-
stantially as specified.
Eleventh. The combination with an electro-magnet of two or more
distinct electric circuits passing through the single wire thereof in
such relative directions as to prevent partially or entirely the magnetic
effect of such currents upon the magnet, substantially as specified.
Twelfth. Two or more electric circuits passing together for a part of
their course through a single wire, the current of each circuit being
preserved intact in that part of its course outside the common track,
all bearing like proportions to each other as when acting separately,
each current measuring an increase in proportion to the amount of
resistance from which it is relieved in the wire of the common track,
substantially as specified.
Thirteenth. The combined manipulating key and receiver, relay, or
repeater, consisting of a magnet, armature and key lever, substan-
tially as specified.
Fourteenth. The device for producing certain movements by means
of electro pulsations of given durations, substantially as specified.
Fifteenth. The combined type wheel motor and impression device by
which motion is given to type wheel by positive or negative pulsations,
one adding the impression movement, but at the same time producing
the type wheel step, the other operating only type wheel movements, or
vice versa, substantially as specified.
Sixteenth. The perforated strip with perforations arranged to operate
in connection with the arrangement of connectors, substantially as
specified.
Seventeenth. The combination with a series of instruments connected to
the same or to different circuits of an electrical or mechanical connection
for controlling any or all the instruments from any one thereof, sub-
stantially as specified.
Eighteenth. The combination with a main line of double sets of station
instruments with circuits crossed from side to side in either or both
directions, substantially as and for the purpose specified.
Nineteenth. The application of printing instruments to duplex circuits
in such manner that the operation of one set of pulsations shall produce

page_text: the movement of type wheel, while the other set of pulsations performs
the printing operations, substantially as specified.
Lastly. The method of reducing the resistance of a telegraphic line
or circuit to its battery current by passing through the same, or a
portion of the same, the circuit of another circuit or circuits, substan-
tially as specified.
In witness whereof, I, the said Robert Coddington, have hereunto
set my hand and seal, this Twenty-seventh day of March, in the
year of our Lord One thousand eight hundred and seventy-five.
ROB. CODDINGTON. (L.S.)