AN IMPROVEMENT IN TELEGRAPHIC SYSTEMS
Year: 1884

page_text: COMPLETE SPECIFICATION.
I, WILLIAM PHILLIPS THOMPSON, Fel. Inst. P.A., of the Liverpool and London
Agency for Foreign Patent Solicitors, 6 Lord Street, Liverpool, in. the County of
Lancaster, Civil Engineer do hereby declare the nature of the said Invention for
"AN IMPROVEMENT IN TELEGRAPHIC SYSTEMS," and in what manner the same
is to be performed, to be particularly described and ascertained in and by the
following statement :—
The Invention more particularly relates to the class of electric telegraphs in
which the messages transmitted are indicated by the frequency, duration and
character of electric impulses rather than to the class in which electric currents or
impulses are employed for actuating or controlling mechanism constructed to print
or stereotype the message in letters or words. The Invention is nevertheless also
applicable to the last mentioned systems of telegraphy and telegraphic apparatus.
It has been customary to employ electric impulses of different lengths, durations
and frequency combined in different ways for indicating the different letters of the
alphabet or other characters and forming the words which embody the telegraphic
message. These currents upon traversing the main line of a telegraphic system
have heretofore been interpreted or translated into the appropriate letters and
words, either by the impressions which they are caused to stereotype upon a
receiving strip of paper, or directly from the. movements of an 'armature of an
electro-magnet which is caused to be vitalized thereby. The movements of the
armature are rendered sensible by sound or, as in submarine cable systems, by the
movements of a ray of light reflected from a galvanometer needle, such an
instrument being substituted for the usual form of electro-magnet. In whatever
manner the message is to be interpreted, it has been customary to employ impulses
differing in length, in duration, or in polarity, which impulses either singly or in
combination designate the different letters of the alphabet or other significant
characters.
The object of this Invention is to provide a system of telegraphy more rapid and
less expensive in its operation than those of the character above indicated, and
which is based upon a principle involving the employment of a less number of
separate electric currents or impulses and which will at the same time destroy or

page_text: otherwise obviate the detrimental effects produced by the so-called static charge
and discharge of the main line.
The Invention consists generally in dividing the letters of the alphabet into
separate and independent groups, preferably seven in number; designating each of
the several groups by a particular electric current or combination of currents; and
in indicating the individual letters contained in any particular group, by the
interval of time elapsing after the group is designated before a succeeding group is
designated, which interval agrees in units to the position of the letter in the first
group. For the convenience of the receiving operator, these intervals may be
marked or divided into periods or units by means of a metronome or by any 1
suitable time-measuring device capable of proper regulation.
The groups may be designated by currents of opposite polarities, currents of
different strengths or of different durations, or by currents separated by different
periods or intervals of time. The particular class, of currents to be employed will
depend upon the circumstances of any particular case. The transmitting device
is organized to transinit these currents in a manner appropriate to indicate the
groups, as well as the position of the letters in the group. This is accomplished by
separating each succeeding group from the preceding group by an interval of
appropriate duration for indicating the letter. The receiving operator recognizes
the groups, as they are successively denoted, by the effects produced by the currents,
and the letters, by the intervals cecurring between the group-indicating currents or
combination of currents.
When electric currents of different polarities are to be used, a method which is
very efficient in submarine caules and other long lines of telegraph, the transmitting
device may be conveniently organized to cause a rotating circuit-closing arm to
pass successively beneath the extremities of two rows of keys arranged in
concentric circles, the individual keys in the two rows being placed in the same
radial lines. The two series are respectively connected with the positive and the
negative poles, of two batteries or other convenient source of electricity and a
current of the corresponding character will be transmitted when a key in either
series is projected into the path of the circuit-closing arm. 'Means are provided for
regulating the rapidity with which the circuit-controlling arm shall revolve, and
the period intervening between the passage of the arm from one pair of keys to the
next succeeding pair, is the same throughout its entire revolution.
At the receiving station an interpreting device of any suitable character such,
for instance, as a reflecting galvanometer, is caused to be actuated by the positive
and negative currents, and casts a reflected ray of light in one direction or the other
according to the polarity of the current. Any convenient device, such for instance
as a metronome regulated to heat once for each pair of keys passed by the circuit-
closing arm of the transmitter, may be employed for the purpose of assisting the
receiving operator in measuring the units of time intervening between the
successive groups of signals.
A suitable device for enabling the receiving operator to manually record the
letters as they are successively indicated, is also located at the receiving station,
and the reflected ray of light is preferably thrown directly upon the key-board of
such an instrument.
Other obvious methods of designating and interpreting the groups may be used
as for instance, currents or impulses of a given strength may be substituted for the
positive impulses, and of an increased or of a diminished strength for the negative
impulses, for the purpose of determining the groups; and these may be interpreted
with the aid of two telegraphic sounders adjusted to respond to the respective
current strengths.
Again it may be found convenient in some instances to employ currents of two
different durations, such as are employed for denoting the "dots" and "dashes"
of the Morse telegraphic code. These group-designating currents may be received
directly upon chemically prepared paper and subsequently interpreted at the
convenience of the receiving operator. It is evident that any of the well-known

page_text: classes of automatic transmitting devices may be employed, as for instance-the
messages may be perforated or stenciled in a strip of paper and afterwards passed
beneath a suitable transmitting stylus.
The letter-groups, into which the alphabet is divided, are preferably seven in
number. The first group, when positive and negative designating-impulses are
employed, is designated by a single positive impulse, and the second by a single
negative impulse. The third group is designated by a positive followed by a
negative impulse; and the fourth by a negative followed by a positive impulse.
Two positive, with an intervening negative impulse, signifies the fifth group; and
two negative, with an intervening positive impulse, indicates the sixth group.
The seventh group is denoted by two positive and two negative impulses alternating
with each other. The groups into which it is desirable to divide the letters of the
alphabet in practice are dependent upon the frequency with which they are
employed in ordinary composition, for it will be evident that it is desirable to
designate the groups containing the letters which are most frequently employed by
means of the briefer signals. For this purpose the letters are preferably arranged
in the following groups, the numerals referring to the number of the group in each
instance-I. E, A, I, O; II. N, U, T, S; III. C, H, P, L; IV. B, Y, R, D;
V. W, M, F, G; VI. K, G, Q, V; VII. X, Z.
The letters of the alphabet having been thus divided into groups, it will be seen
that each letter may be further designated according to the position which it
occupies in its group, thus "E" is the first, "A" the second, "I" the third and “O”
the fourth letter in the first group. The interval of time therefore which elapses
after any particular group has been designated by its signal before a succceding
group signal is received, indicates to the receiving operator some particular letter
in that group. Considering that the letters are to be designated by intervals or
units of time elapsing after the group signal has been transmitted, and that these
units are designated by a metronome, the following tabulated form will serve to
illustrate, first the group-signals, and second the units of time or beats of the
metronome by means of which the letters are indicated
:

page_text: combination of currents may be employed for indicating the marks of punctuation
and spaces, such for instance as two positive currents for a period and two negative
currents for a space.
It will be observed that the pulsations employed for indicating the groups are
each composed either of a single current or of a series of currents of alternating
polarity. Such a combination of currents effectually prevents any detrimental
results which have heretofore been encountered from a static condition of the main
line or cable. It is well-known that the effect of a current of opposite polarity
succeeding any given current, is to neutralize the static discharge which otherwise
succeeds the interruption of the preceding current.
The time which lapses between the indication of any two successive groups of
letters, is sufficient to allow the static discharge of the last current employed to
take place, before the next succeeding group is indicated.
When it is desired to employ electric currents of different strengths for
furnishing the group-indicating signals, the same system of group divisions is
applied, the positive current being replaced by currents of a given strength and the
negative currents by currents of a greater or of less strength. The currents of
different strengths may be of the same or of opposite polarity as desired.
Likewise the substitution of currents of different durations may also be effected
by assigning a current of a given duration in place of a positive current and a
current of another and distinctive duration in place of a negative current
wherever those currents occur in the system first described.
In the accompanying Drawings, Figure 1 is a diagram illustrating the method of
carrying the Invention into execution, in connection with an organization of
apparatus especially adapted to submarine cable systems, and Figures 1a, 2 and 3
illustrate certain details in the construction of the transmitting device and the
time-measuring instrument. Figure 4 is a diagram illustrating the Invention as
applied to a system in which currents of different strengths are employed.
Referring to Figures 1, 1a, and 3, A represents a transmitting key-board,
which is divided into two insulated series B1 B2 of transmitting keys. These
scries are respectively connected with the positive and with the negative poles of
two batteries E1 and E2, by conductors 1 and 2. The remaining poles of these,
batteries are connected with the earth by a conductor 3. The keys in the two
rows B1 and B2 are arranged in the same radial lines and the distance between
the successive keys in each row is the saine throughout the circular series. Beneath
the keys extends a circuit-closing arm F, which is placed in electrical connection
with a main line or cable L. The circuit-closing arm F is provided with suitable
means, preferably an electric motor, for causing it to revolve at a determinate rate
beneath the lower extremities of the circuit-closing keys. Each key is constructed,,
as shown in Figure 2, with a beveled or rounded extremity, which is normally held
out of the path of the circuit-closing arm F by means of a spring entering an
annular groove or notch 2. Each key may however be pressed downward so that
its lower extremity will project into the path of the circuit-closing arm F. This
arm, by striking against the key during its revolution, not only completes the
electrical connections of one or the other battery El or E2 with the main line L,
accordingly as the depressed key is in the series B1 or B2, but it also serves to
force the key upward again into its normal position, without arresting the
movement of the arm.
The currents which may thus be transmitted by means of the key-board to the
main line, are caused at the receiving station, to traverse the actuating coils of a
reflecting galvanometer G, of well-known construction. The movements of the
galvanometer needle are rendered apparent by means of the movements thus
imparted to a ray of light falling upon a mirror g which is supported upon the
arbor of the galvanometer needle. Such a ray of light is for convenience reflected
upon a key-board, hereinafter described, and is bent toward the left hand or
toward the right accordingly as the actuating current or impulse is of positive or
negative polarity. Tho galvanometer shown in the Drawing consists of a

page_text: permanent magnet 71, between the poles of which is delicately suspended a
needle g 2. Surrounding the needle is a coil of insulated wire g 3, the convolutions
of which extend in the direction parallel with the normal direction of the needle g 2.
A current of a given polarity traversing the coils g 3, serves to deflect this needle
in one direction, and a current of opposite polarity deflects the saine in the opposite
direction. The ray reflected by the mirror g, is derived from a flame g 5 and is
preferably cast, as before stated, upon a key-board P, though it may be received
upon an independent screen. By the movements of this reflected ray, the polarities
of the currents transmitted are readily determined by the operator. The receiving
operator may therefore readily determine the particular group of letters at any
time selected by the transmitting operator, and by measuring the intervals which
elapse between the successive groups, he determines the particular letters selected.
By means of a metronome, the intervals may be conveniently divided into units
equal to the time occupied by the circuit-closing arm in passing from one pair of
keys in the transmitter to the next succeeding pair. Such a device is shown at H,
and it may be of any convenient construction. In the construction shown, a
revolving wheel 1 is driven at a constant rate by means of a weight h2. From
the periphery of this wheel extends a series of equi-distant, radial pins h 3, which
This escape-
are successively engaged by means of a vibrating escapement 4.
ment consists of two teeth h5 and 6 respectively facing each other but in
different planes and carried upon one arm of the vibrating pendulum
Sufficient distance intervenes between the planes in which the edges of the
teeth h 5 and 6 are placed, to permit the passage of the teeth or pins 3 between
them when the pendulum is vibrated laterally. Upon the pendulum rod are
carried one or more weights h 8 and h 9, which may be adjusted for modifying the
rapidity with which it will be vibrated under the influence of the wheel h 1. The
sound obtained by the striking of the successive pins against the teeth of the
escapement is employed for measuring the successive beats and thus the units of
time into which the intervals are divided.
7.
There is also placed at the receiving station a recording instrument which may
consist of any suitable form of type-writer. The key-board of this instrument is
preferably arranged as indicated at P. Considering the line p to be the center of
the board, the keys in the lower left-hand line, commencing at the left extreme,
are designed to represent the letters contained in the first group, namely, "e a io."
The line above represents the letters in the third group, namely, "chpl;" like-
wise the line next above represents the letters "w mfg;
and the two keys
in the upper line represent "x z." The keys arranged upon the right-hand side of
the central line indicate, in the same manner, the letters contained in the right-
hand groups. It will be seen that the groups comprised upon the two sides of the
board are arranged accordingly as the first impulse or current employed for
representing the group is a positive current or a negative current, those represented
by a positive primal current being upon the left-hand side of the board, and those
by a negative primal current upon the right-hand side. In the central line two
keys p 1 and p2 are placed, which are respectively designed to represent a space
and a period.
At a convenient place upon the key-board P is formed a scale or plane surface P 1,
upon which the ray of light from the galvanometer is reflected. This construction
renders it convenient for the operator to watch the movements of the ray while
he is operating the keys. An independent screen may however be substituted for
this last named construction. In practice also the operator may, in some instances,
dispense with the mirror and reflected ray of light and determine the groups by
watching the movements of the galvanometer needle, for it will be readily under-
stood that it is not necessary to observe the degree of movement of the needle, but
merely its direction.
Thus far the description of the Drawings has been given in connection with the
-use of electric currents distinguished from each other by their polarity. A method

page_text: of adapting the Invention to apparatus organized to employ electric currents of
different strengths, will be described in connection with Figure 4.
In this organization a single battery E3, is substituted for the batteries E 1
and E 2. One pole, say the negative, is connected with the carth by a conductor 4,
and the remaining pole is provided with two conductors 5 and 6, respectively
leading to the series B1 and B2 of transmitting keys. In one of these conductors 6,
is included an artificial resistance R adapted to reduce the currents which aro
transmitted to line by means of the keys B 2. The two classes of current thus
obtained may, for convenience, be considered as having the one double the strength
of the other.
At the receiving station these currents are caused to actuate one or the other of
two relays S1 and S2, which are respectively adjusted to respond to currents
transmitted through the agency of the keys B1 and B2. These relays may be of
any well-known form. In the Drawing the relay S 1 is represented as an ordinary
electro-magnet with an armature-lever 8 1 which is adjusted to respond to electric
currents of the strength transmitted by the series of keys B1, but not of the
strength transmitted by the series B2. The connections of a local circuit, including
a sounder T 1, are designed to be completed by this relay, when the armature s 1
is against its front contact-stop. The relay S2 is provided with an armature-
lever 82 and a supplemental levers 3, against which it strikes when attracted by
its electro-magnet. The armature-lever 8 1 is adjusted to respond to currents of the
strength transmitted by the action of the series of keys B2. When however a
current of the strength transmitted by the keys B 1, traverses the main line, the
armature is attracted with suflicient force to actuate the supplemental lever 83 also
and to impel it away from its back contact-stop s 4. A local circuit, including a
sounder T 2, has its terminals respectively connected with the armature-lever & 2
and the stop 8 4. The connections of this circuit will therefore be completed only
through the influence of currents transmitted by the series of keys B 2.
The two sounders T1 and T2 are respectively placed near the opposite
extremities of the receiving koy-board P and the receiving operator will be able to
readily determine the group signals from the action of these sounders, in the same
manner as described with referenco to Figures 1, 1a, 2 and 3.
The theory of the Invention may be still further carried out by substituting for
the currents of opposite polarity or the currents of different strengths, currents
of other distinctive characteristics; and in some instances it may be found desirable
to employ currents of both alternating polarity and different strengths.
It is evident that numerals may be added to the series of letters and indicated
by group signals in the same manner as described and that the combinations of
currents may be indefinitely extended.
Having thus described the nature of this Invention and the manner in which
it is to be performed, as communicated to me by my foreign correspondent, I would
have it understood that I claim :-
1. The herein before described method or system of telegraphy, which consists in
distinguishing different groups of characters by an electric current, impulse or
combination of electric currents or impulses, and the individual letters, contained in
such groups by distinctive intervals of time occurring after the group-signal has
been given and before a succeeding signal is commenced.
2. The herein before described method or system of telegraphically indicating
different characters of a series, which consists in dividing such series into arbitrary
groups, designating each of the several groups by means of electric currents
possessing particular characteristics, and indicating the individual letters in the
several groups by different intervals of time succeeding the group-designating
currents.
3. The herein before described method or system of telegraphy, which consists
in indicating different groups of letters or characters by electric currents of
distinguishing characteristics and indicating the individual characters by different

page_text: numbers of units of time elapsing after such groups are indicated; substantially as
described.
4. The hereinbefore described method or system of telegraphy, which consists in
designating each particular group of letters by the transmission of electric
currents and each individual letter in such group by a cessation of such currents..
5. The herein before described method of indicating the individual character of a
series, which consists in indicating the groups, into which said series is divided by
electric currents, and assigning to each character in each group a distinctive period
of time by the occurrence of which, after the group has been indicated, that
character is designated.
6. The hereinbefore described method of indicating the different characters in a
series, which consists in dividing such series into groups, designating the different
groups in an arbitrary manner, and indicating the individual characters in such
groups by the measurements of a metronome.
7. The herein before described method of transmitting telegraphic messages,
which consists in indicating different groups of character-recording keys, corre-
sponding to the characters which constitute an embodyment of such message, by
arbitrary electric signals, and indicating the particular recording key in a designated
group by the interval occurring after such group has been designated before
another signal is commenced.
8. The herein before described method of indicating the different keys of a
character-recording key-board which correspond to the characters embodying a
telegraphic message, which consists in indicating the side of such board upon which
such keys are located by primal signals; the particular line of keys cortaining
such keys, by the same primal signal or a combination therewith of other signal
or signals; and the particular key in such line, by the units of time measuring the
intervals between the signals or combination of signals.
9. The herein before described method of indicating the different characters
contained in a series, which consists in designating different groups of said series
by the movements of a reflected ray of light, and indicating the different characters
contained in such groups by the period during which the direction of such ray of
light is unchanged.