IMPROVEMENTS IN PRINTING TELEGRAPHS
Year: 1884

page_text: COMPLETE SPECIFICATION.
I, WILLIAM PHILLIPS THOMPSON, Fel. Inst. P. A. of the Agency for Foreign
Patent Solicitors, 6 Lord Street, Liverpool, in the county of Lancaster, and
323 High Holborn, in the county of Middlesex, Civil Engineer, do hereby declare
the nature of the said invention for "IMPROVEMENTS IN PRINTING TELEGRAPHS"
(a communication from abroad by Charles Goodwin Burke, of Richmond Hill in
the county of Queens and State of New York, in the United States of America,
Electrician) and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
The invention relates to the class of electrical apparatus which is employed for
telegraphically transmitting messages or dispatches over a single main line
conductor, and obtaining a record of the same in the form of impressions of
the characters constituting or embodying the messages or dispatches, which
impressions are obtained from one or more type-wheels; and it also relates to
the method of transmitting and receiving the electrical impulses whereby the
communications are conveyed.
The object of the invention is to provide means for transmitting upon a single
inain line conductor electric impulses adapted to actuate the type wheels of a
printing telegraph instrument located at a distant station, and to so organize the
apparatus that a single message may be transmitted, or, when it is so desired,
impressions may be taken from either of two type wheels at will, and in such a
manner as to constitute two distinct records, the operation of transmitting and
receiving two messages being carried on at the same time.
A further object of the invention is to provide means whereby the dispatch or
dispatches which it is desired to transmit, may, if it is so desired, be recorded upon
a transmitting cylinder in such a manner as to render them capable of being
automatically transmitted therefrom if desired.
In carrying out the invention it is necessary to construct the apparatus in
a novel manner, and to operate the same in a manner which will be described
in connection with the apparatus. The apparatus may be employed either for
11...מ

page_text: transmitting one message upon the line or the parts may be so combined that two
or more messages may be in the process of transmission at the samo time.
For convenience of description the organization of the apparatus as employed for
single transmission will first be described, and afterward a description of the
method of employing the same for the purpose of carrying on the transmission of
two independent imessages will be given.
The first part of the invention consists in constructing the apparatus sub-
stantially in the following manner: Each transmitting key-board is circular in
form and is provided with more than one key corresponding to the letters of the
alphabet most commonly employed, that is to say, each letter or character is
provided with a number of keys proportionate to the frequency of its employment
in ordinary use. The keys are also arranged in such a manner that each and
overy key falls in a different radial line of the circular key-board. Beneath these
keys is rotated a contact arm which is designed to form an electrical connection
with any key which may be depressed, and also to raise such key and restore it to
its normal position upon making such contact. The keys themselves constitute
one terminal of an electric circuit and the revolving arm the other. Hence, by the
contact of the arm with one of the keys, an electric circuit is completed, which
may be employed either for actuating a message-preparing device, or for directly
actuating a receiving instrument having upon the periphery of its typo-wheel a
series of characters corresponding to the keys of the transmitter.
Considering first the means of preparing or storeotyping the message for
subsequent automatic transmission: A cylinder may be employed for receiving the
message, which is rotated by mechanical means and which imparts a corresponding
movement to the revolving arm. The cylinder is provided with an inking pen
which is caused by the revolution of the cylinder to describe a helical line of
non-conducting ink upon its surface. This inking-pen is however controlled by an
electro-magnet, which, when vitalized, raises the pen from the surface of the
cylinder, thereby producing a break in the line of non-conducting ink, the length
of which is determined by the time during which the pen remains thus raised.
When it is desired to charge the cylinder with a message, this electro-magnet is
included in a circuit capable of being completed by the circuit-closing arm, so that
each time this arm makes contact with one of the depressed keys the electro-
magnet will be vitalized and a corresponding interruption of the line of non-
conducting ink will be produced. As the provement of the arm is coincident with
that of the cylinder, the angular position upon the cylinder of the interruption
thus occasioned, will correspond precisely to the position of the key by means of
which the interruption was occasioned. The cylinder having been thus prepared,
a transmitting arm or stylus which by similar mechanical means is caused to
follow the line of non-conducting ink upon its surface, is employed for transmitting
impulses from a main battery upon the main line by its successive contacts with
the metallic cylinder at the point of interruption of the line of non-conducting ink.
The cylinder is provided with means for transmitting upon the main line electric
impulses of alternating polarity of such character as to advance the type wheel of
the receiving instrument step by step, in a manner well understood. By revolving
the cylinder as rapidly as may be desired, a series of alternating impulses for
actuating the type-wheel of the receiving instrument are transmitted to line, and,
at the moment the transmitting stylus makes contact with the cylinder, a current
corresponding in polarity to the impulse last transmitted, but having an additional
strength sufficient to actuate the printing mechanism of the receiving instrument, is
transmitted to the main line. The intervals at which such impulses will be
transmitted are primarily determined by the relative angular position of the keys,
through the instrumentality of which the interruptions were occasioned. The
number of pole changing segments employed for actuating the type wheel of the
receiving instrument is equal to the number of keys upon the key board. The
number of impulses therefore which will be transmitted to line by means of this
pole changer between any two successivo impulses of increased strength, will be

page_text: equal to the number of keys intervening upon the key-board between the two keys
by means of which the two interruptions were occasioned, and the type wheel
will be advanced one character for each such impulse. By means of the stronger
impulses impressions will therefore be taken from the type-wheel corresponding to
the keys by means of which the open spaces upon the transmitting cylinder were
occasioned.
When however it is desired to transmit from the key-board directly to the main
line, without the intervention of the cylinder, this may be accomplished by
connecting the source of the stronger currents directly with the transmitting
koy board and substituting for the electro-magnet employed for actuating the
inking pen, the electro magnet of the recoiving instrument which may of course
be placed at any distance from the transmitter.
The receiving instrument is constructed upon essentially the same general plan
as other well known receiving instruments for printing telegraphs, with this
exception; the type-wheel, instead of having a single series of characters corro-
sponding with the alphabet, is provided with a number corresponding to thoso
employed upon the key-board, and preferably this number is one hundred and
twenty six. This series is broken by eighteen blanks or spaces interposed at
regular intervals upon the periphery of the type wheel. The type-wheel is also,
for the double purpose of rendering it as light as possible and of making its
characters more sharp and distinct than those of the ordinary type wheel,
constructed of aluminum.
Further points of distinction will be set forth in connection with the description
of the method of double transmission.
For the purpose of the double transmission, two transmitting key-boards aro
employed in connection with the pole-changing devico, and these are adapted at the
proper times to completo the connections of a shunt circuit around the artificial
resistance, provided a key of one of the key-boards be depressed; an increase in
the strength of the current occasioned in this manner is employed for effecting an
impression from one or the other of two receiving type-wheels, accordingly as
the key employed for effecting the increase is located upon one or the other of the
transmitting key boards.
It is obvious however that some means must be provided for causing tho
impulsos of increased strength to be distributed between the press-magnets of the
two receiving type-wheels in their proper order, so that the impulses of increased
strength occasioned by depressing the keys of the respective key-boards shall be
caused to traverse only the electro-magnet designed to effect an impression from tho
type wheel corresponding to that key board. To accomplish this result means are
provided for causing the circuit at the receiving station to be completed from the
main line first through one of the press magnets and then the other, for each
reversal in the polarity of the current transmitted for actuating the escapement.
There are also provided at the transmitting station means for occasioning tho
completion of the shunt circuit around the resistance, first by means of a key upon
the key-board corresponding to the first of the type-wheels, and then by means of
a key upon the second of the key-boards, that is to say, the one corresponding to
the second type-wheel. In other words, for cach reversal of the polarity of the
currents employed for actuating the escapement, the circuit will be completed,
independently of the resistance, from the one key board to the main line and
through the corresponding press-magnet, and then from the second key-board
through the main line to the second press magnet. If therefore a transmitting key
upon the first board be depressed, and the circuit connections be completed through
that key-board at the moment the first named system of circuits are connected
with the main line, then an impression from a type upon the first wheel will be
effected, and likewise if the key upon the second transmitting key-board be
depressed at the moment the second system of circuits are connected with the main
line, then an impression will bo effected from the second type wheol.

page_text: It is evident that by properly adjusting the circuit closing devices of the
transmitting key boards an impression from one type wheel will be effected
immediately after an impression has been taken from the other, and that two such
succeeding impressions may be taken during the transmission of an electric current
of one polarity only.
For the purpose of thus insuring that the circuits shall be complete at the
transmitting station first through the one and then through the other of the two
transmitting key-boards, two additional pole changing devices may be employed,
cach having its conducting segments of approximately half the width of the
segments of the main pole changing device. These additional pole-changing
devices aro respectively applied to the two transmitting key-boards, the contact
brushes being respectively connected, with the keys, while the circuit closing arms
which are designed to revolvo beneath the keys, are connected with the main line
around the artificial resistance. The conducting segments of the additional pole
changing device which is applied to one of the transmitting key boards, are so
connected that they will make contact with their contact brush at the same time
the corresponding segments of the main pole changing device make their successive
contacts with their contact brush. The contact segments of the second additional
pole-changing device are however so placed with respect to the contact brush
applied thereto, that the contact between the same and the brush will be during
tlie latter half of the period of contact which is made. between the corresponding
segments of the main pole changing device and its brush.
It will appear that it will not at any time be necessary for both circuit-closing
arins to be simultaneously in contact with their respective keys. It is preferable
therefore that the one contact arm should be at such a distance behind the other,
with reference to their respective series of keys, that the contact of one of the
circuit closing arms with any key may occur immediately after the other contact
arm has separated from the corresponding key upon the other key-board. In
other words while ono contact arm is passing beneath a key upon its key board,
the remaining arm will be between two of the keys upon the remaining board, so
that it is impossible for both arms to simultaneously make contact with any one of
the circuit-closing keys.
A single escapement is employed for conveying a step-by-step movement of both
tho type-wheels, and this escapement is actuated by means of the alternating
electric impulses transmitted by the main pole-changing device. Upon the shaft
carrying the type-wheels are carried two circuit-controlling devices, each consisting
of a series of alternating conducting and non-conducting segments, in number
corresponding to the number of segments employed in the main pole-changing
devices of the transmitter. The contact segments are connected with the main
line, while the contact brushes which are applied to those circuit controlling
devices, are respectively connected with the coils of two press-magnets which are
respectively designed to effect impressions from the two typo-wheels. These circuit-
controlling devices are so applied to the shaft of the type-wheels that they will act
alternately to complete the main line connections first through the one electro-
magnet and then through the other; and they are also so organized that the moment
of completion through the first electro magnet will be at the commencement of an
alternating current of the character employed for actuating the escapeinent, and
through the second electro-magnet during the period occupied by the latter half of
that same impulse, so that each incoming current of a given polarity will find its
way to the earth, first through one electro-magnet and then through the other. If
the strength of such a current be increased by shunting the resistance at the trans-
mitting station the electro-magnet which it traverses will be vitalized and an
impression will be effected from the corresponding type-wheel. Such an impression
will be effected, as has already been shown, from the particular type-wheel corre-
sponding to the key-board through which the increase in strength was occasioned,
and the type wheel being organizod to revolve in unison with the circuit closing
arms, the particular typo printed will correspond to the particular key depressed.

page_text: The escapement device employed for permitting the step-by-step movement of
the type wheel is such that the type wheels will advance continuously during the
movement of the escapement-anchor from one limit to the other of its vibration.
When therefore an electric impulse of the character employed for actuating the
same is first transmitted through the coils of the escapement-controlling electro-
magnet the type-wheels and also the circuit-controlling devices advance and they
continue to so advance until the armature has completed its entire movement in a
given direction. The circuit-controlling devices are so organized that the completion
of the main line connections will be through one of the printing magnets during the
first portion of this movement, and through the second printing magnet during
the latter half of its movement. It will appear therefore that the impression from
at least one of the type wheels must be effected while the type wheels are in
motion. That is in fact accomplished, and for the purpose of so doing without
retarding the movement of the type-wheels, and without blurring the impressions,
it is preferable to construct the platen and its supporting lover in such a manner that
its direction of motion shall be the same as that of the revolution of the type-wheels,
instead of in the opposite direction.
It will be understood that characters may be printed from either type-wheel
without reference to the other; and that it is not necessary that impressions should
be taken from the two alternately, but either type wheel may be printed from
continuously. When records are being made by both type wheels during the same
time, this is accomplished without lessening the speed of operation of either type-
wheel. For considering, for instance, that all the keys upon both transmitting
boards were depressed in succession, each printing-lever would operate to effect an
impression from the corresponding type wheel of each character upon the same in
succession, and the time which must necessarily be allowed for the downward
movement of each lever, after an impression has been made, will be occupied by
the upward movement of the other lever; so that while impressions are being taken
alternately from the two type wheels the impressions from the second typo-wheel
will be taken during the time which must necessarily be consumed by the movement
of the first printing platen away from its type-wheel, and vice-versa.
Referring to the accompanying drawings, which illustrate this invention, Fig. 1
is a plan view of the transmitting key-board and revolving cylinder, showing also
in diagram the construction of the receiving instrument and its circuit connections
as employed for single transmission. Fig. 2 is a side elevation of the transmitting
cylinder, and Fig. 3 is a side elevation (partly in section) of the key-board,
showing the mechanical connection between the same and the axis of the
cylinder.
Fig. 4 is a diagram showing the general organization of apparatus and the
circuits therefor, as employed for double transmission. Fig. 5 is a side clevation
of the receiving instrument as organized for double transmission, and Fig. 6 is a
plan view of the transmitting devices. Fig. 7 is a side elevation of a particular
form of circuit closing device which is also shown in connection with Fig. 3. Fig. 8
is a side elevation of the type wheel and of a special form of circuit closing device
for determining through which printing magnet the circuit of the main line shall
be completed.
Referring to Figs. 1, 2 and 3, A represents a shaft which is mechanically revolved
by any suitable means, and is preferably so arranged as to be capable of being
driven at a speed which may be varied at will. Upon this shaft is carried a
transmitting cylinder B and also two pole-changing devices C and D which will be
hereinafter fully described. At the extremity of the shaft A is a vertical beveled
gear-wheel E which engages with a horizontal gear-wheel E² of the same size and
having an equal number of teeth. Each revolution, therefore, of the shaft A will
cause a single revolution of the wheel E. Upon the wheel E is carried a revolving
circuit closing arm f³, the function of which is to complete the connections of an
electric circuit by making contact with the lower extremity of any one of a series
of circuit-closing keys f which extend downward through a key-board F above

page_text: the circuit-closing arm. The keys f" are normally held up out of the path of the
circuit closing arm f1, by means of friction-springs f³ each one of which is adapted
to enter an annular groove f* formed near the lower extremities of the respective
keys. Any one of the keys however may be depressed a sufficient distance to carry
the groove beyond the reach of the spring and bring its lower extremity into the
path of the circuit-closing arm f'.. The lower extremities of the keys are preferably
rounded or beveled, as shown in Fig. 3, in such a manner that the contact of the
arm f¹ therewith will force them upward and thus rostore them to their normal
position.
The keys on the key-board are in this instance arranged in the manner indicated
in the drawing in eighteen curved rows radiating from the centre of the circular
key board, and each key occupies an angular position, or falls upon a radial lino
of the key-board differing from every other key, so that the revolving contact-armf¹
can strike against but one key at a time. At some convenient point, and preferably
at the outer end of each of the eighteen series of keys thus formed, is placed a key
designed to correspond with a blank or space upon the type-wheel of the receiving
instrument. The remaining keys each correspond to a letter of the alphabet or with
a numeral. Each radial series is preferably further designated as being essentially a
consonant series and a vowel series, a series of vowels intervening between each
series of consonants. Each letter of the alphabet, whether consonant or vowel, is
repeated upon the key board a number of times proportionate to the number of
times it is ordinarily employed in every one hundred and twenty six letters of
average composition, and they are arranged to correspond as nearly as possible in
succession to the actual succession in which they are found to be most commonly
employed. After a careful study'the following arrangement or succession of letters
has been found to conform most nearly to such requirements: BN D F G M K-
JYE AIO U-SCPLTHR-V WE AIOU-SCPLTHR-QWEA
IO U BND FGM K-XYEAIOU-SOPLTHR-VWEAIOU―
BND FG MK-JYEAI OU-S CP LTHR-Q WE AIOU-BND
FGMK-ZYEAIO U-S CPL THR-X WE A I O U.-It will be
observed from an inspection of this series of letters and also from an examination
of the key board as illustrated in Fig. 1, that during a single revolution of the
circuit closing arm there are nine different points at which a contact may be made
with a key designated by the letter "A," and the same is the case with the other
principal vowels. Likewise the principal consonants are repeated a number of
times proportionate to the frequency of their employment. Thus the letter R is
represented five times and the letter M four times, while the lotter Z is employed
but once, and letter Q but twice. The keys may however be arranged in series of
four each as indicated in Figs. 4 and 5.
Above the key-board F extends an arm or index F³ which is carried upon the
arbor of the beveled gear-wheel E. This index is exactly above and moves in
unison with the circuit-closing arm f¹, and serves to indicate to the operator the
precise position of that arm.
The transmitting operator may thus in preparing his message depress his keys as
rapidly as possible, each key remaining depressed until the contact of the circuit
closing arm forces it upward again, the only requisite on the part of the operator
being that he depress the keys in their proper succession, and that he does not pass
around the key board more than once for each revolution of the circuit closing arm.
There may however, it is evident, be as many as eighteen or twenty or oven more
keys depressed at a time in their proper succession and these keys will be
successively struck by the circuit' closing arm, which thereupon restores them ono
by one to their normal position, passing on to the next key. In practice it is
found that an average of three words may be transmitted by a single revolution
of the circuit closing arm f
The key-board which has been described may be employed for transmitting
directly to the main line the impulses occasioned by the circuit-closing arm, or it
may be employed for preparing the cylinder B with a series of conducting surfaces

page_text: or interruptions of a non-conducting line upon a conducting surface, which inter-
ruptions succeed each other at the proper intervals to correspond with the impulses
which are transmitted from the key-board.
The method of transmitting the impulses directly to the receiving instrument
will first be described. The pole-changing device Č upon the shaft A, consists of
two series of alternating conducting segments, c¹ and c. The series c¹ are all in
electrical connection through a conductor 1, including an artificial resistance R³,
with one pole, say the positive, of a battery O', and the serios c³ are in like con-
nection, through a conductor 2, including a similar resistance R³ with the negativo
pole of a battery O' corresponding in electro-motive force to the battory O¹. The
remaining poles of each of these batteries are connected with the earth by a
conductor 3. A contact-brush c³ resting upon the surface of the disc C, is brought
by the revolution of the shaft A successively into contact with the alternating
segments c¹ and c². This contact brush C, which is connected through a conductor 1
with a main line L leading to the receiving instrument, is thus put alternately in
communication with the batteries 0¹ and 0%, and a series of positive and negative
impulses are transmitted to line. The number of contacts thus made by the
brush, during a single revolution of the shaft A, is equal to the whole number of
keys employed upon the keyboard, that is to say, one hundred and forty four, and
these impulses proferably succeed one another, cach immediately upon the inter-
ruption of the preceding impulse. Thoro will thus be transmitted to the main line
during a single revolution of the shaft A, one hundred and forty four impulses,
seventy-two being of positivo polarity and seventy two of negative, and theso
impulses will alternate with each other. Such impulses are employed for imparting
to the type-wheel T of the receiving instrument one revolution for each completo
revolution of the shaft A, without actuating the printing mechanism.
The second pole-changing device D is precisely similar in its construction to the
pole changer C. It is provided with two series of conducting segments and d³
which are respectively connected directly with the positive and negative poles of
the batteries O¹ and O' around the resistances R¹ and R' by conductors and 5
respectively. The currents from these batteries when not forced to traverse the
resistances R' and R' bave sufficient strength to actuate the printing device of the
receiving instrument. The contact brush d³ of the pole changing device D is -
connected through a conductor 6 with a switch V' which may be placed in contact
with a point or v³. The contact point is connected through a conductor 7
with the key-board F and thus with all the keys f, while the contact arm f' is
connected through a conductor 8 and a switch V, with a conductor 9 leading to the
main line L. It will be seen, therefore that the circuit of the batteries O¹ and O'
around the resistances R, will normally be open at the transmitting koy-board,
even while the connections are complete through the contact brush. When
however one of the keys f is depressed, the contact of the arm f' therewith will
cause the circuit connections of the particular battory 01 and 02 which chances to
be connected through the pole changing device D with the brush ³, to be completed
around the corresponding resistance so as to short circuit or shunt it and an impulse
of increased strength will be transmitted to the main line. The two pole changing
devices are so applied to the shaft A and the brashes are so adjusted that this
increase in the strength of current will commence after the same battery has been
connected to lino through the corresponding resistance R and will be interrupted
before the connection has been interrupted so that the printing platen of the
receiving instrument will have been actuated and returned to its normal position
before the interruption of the current or impulse by means of which the type-wheel
is actuated. The movements of the type-wheel will therefore be practically
uninterrupted inasmuch as the impressions will be taken between its successive
stops.
The contact of the arm f¹ with a key f which is depressed, will not only cause
the strong current or impulse to be transmitted, but will immediately raise the
key to its normal position, and move forward without interruption to the next

page_text: succeeding depressed koy. There will thus bo practically no detention of the
circuit-closing arm.
Considering now the operation of the receiving instrument, the alternating
impulses from the batteries O' and O³ are caused to traverse the coils of a double
electro-magnet M having a vibrating polarized armature m² mounted between tho
confronting poles. This armature carries an anchor escapement m² engaging the
teeth of a ratchet wheel m³ carried upon a type wheel shaft . The alternating
impulses cause the armature m¹ to be thrown to and fro between the confronting
poles of the electro magnet M, in a manner well understood, and its movements
serve to permit the advance of the ratchet wheel step-by-step, in response to the
constant force exerted thereupon by a weight or spring applied thereto in the usual
manner. Upon the shaft t¹ is mounted a type wheel T which has engraved upon
its periphery a series of characters corresponding both in form and order of succession
to the characters upon the transmitting koy-board F, and it.is also provided with
a space intervening between each successive seven letters corresponding with the
respective outer keys of the key-board. The type wheel is necessarily of a larger
circumference than those of ordinary construction, and, for the purpose of rendering
it as light as possible, and at the same time making the characters more sharp and
distinct than those upon the ordinary type wheel, it is preferred to construct it of
aluminium as it is found that this metal will excellently serve both requirements.
An electro-magnet P which is included in the circuit of the main line, is provided
with an armature n¹ fixed upon a lever n³ which carries a printing platen n³ for
taking impressions from the type-wheel T. The parts are however so adjusted
that the armature n¹ will not respond to electric impulses of a strength no greater
than is required for actuating the escapement-device (that is to say to currents
transmitted from the batteries O by means of the pole-changing device C), but only
to impulses of greater strength such as are transmitted by means of the polo-
changer D. It will be seen thus that for each alternating impulse which is trans-
mitted by the pole changer C, the type wheel T will bo advanced one letter or
space corresponding to a key upon the transmitting key-board, and that for each
revolution of the arm for shaft A, there will take place one revolution of the
type-wheel, so that if an impulse of increased strength be at any moment trans-
mitted by the contact of the arm f¹ with a key f³, the electro-magnet P will be
vitalized and the platen n³ will take an impression upon paper from the type-wheel
of the type corresponding to the key with which the contact was made, provided
that the type-wheel and transmitting apparatus are in unison with each other. For
insuring that such a unison shall exist any well-known suitable form of unison
device may be employed.
Referring now to the method of preparing the messages upon the cylinder B,
and transmitting therefrom automatically, instead of transmitting directly from the
key-board F, the cylinder B is provided with an inking pen b', which is supported
upon a carriage B', together with an electro-magnet B and ink reservoir. B³. The
carriage B¹ is supported upon the frame of the machine and is driven laterally by
means of a screw-threaded rod 63 extending parallel with the cylinder B. The
rod b³ is actuated by the revolution of the cylinder, and hence if the inking pen b¹
rests upon the cylinder, a continuous helical line will be described upon its surface.
A suitable non-conducting ink is supplied to the pen from the reservoir B³, and this
ink is applied to the cylinder so long as the pen remains in contact therewith. The
electro-magnet B however acts to raise the pen from the surface of the cylinder
whenever an electric circuit is completed therethrough by reason of the attraction
it exerts upon an armature B carried upon one arm of the lever supporting the
pen. This electro-magnet is included in the circuit of a local battery of the circuit
of which may in turn be completed in the following manner :-One pole of the
battery o is connected through conductor 10.with a switch S, which when in
the position shown in dotted lines, constitutes the connections of the battery to
the key-board F. The remaining pole of the battery of is connected, through the
coils of the electro-magnet B², with the circuit-closing arm f¹. When this battery.

page_text: is thus connected with the key-board F, the switches v¹ and V may be opened; unless
. it is desired to transmit at the same time to the receiving instrument, in which case
they may remain in the same position as already described in connection with the
batteries O¹ and O. When therefore the arm f¹ makes contact with any depressed
key f, an impulse will be transmitted from the battery o¹ through the coils of the
electro-magnet B³, and the pen b¹ will be raised from the surface of the cylinder
thereby causing an interruption of the continued line of non-conducting ink, at a
point corresponding to the point at which the key is located by means of which
the impulse is transmitted. That is to say, if two keys upon the key-board be
depressed, the number of impulses which will be transmitted by means of the
polo-changing devico C during the passage of the intervening section of non-
conducting ink past a given point, when the cylinder is employed for transmitting,
will correspond to the number of keys which have been passed by the circuit-closing
arm in moving from the first named key to the second key which was depressed.
When the cylinder B has been thus charged or prepared with messages for
transmission, it is employed for automatically retransmitting those messages in
the following manner: Upon the carriage B¹ is supported a transmitting stylus P¹,
which, during the preparation of the message has been raised from contact with
the cylinder. When however it is desired to transmit, the carriage B¹ is moved to
its starting point and this arm is allowed to rest upon the cylinder while the
inking-pen is raised therefrom. A conductor 13 leading from the switch-point v³
is employed for substituting for the connection of the brush d³ with the key-
board Fa like connection with the cylinder B when the switch v³ is in the position
shown in dotted lines. The switch V is also moved into position shown in dotted
lines, thereby substituting for the connection from the circuit closing arm fla
connection through the conductor 14 with the transmitting stylus P¹. If then the
cylinder be revolved the series of alternating impulses from the batteries O will be
transmitted to. line through the resistances R, in precisely the same manner as
already described with reference to the key-board F. Instead however of the
impulses of increased strength being transmitted directly from the key board,
corresponding impulses will be transmitted at the proper intervals by means of the
stylus P and these impulses will cause the printing magnet to be actuated in
precisely the same manner as described with reference to the key-board F.
Referring now to Fig. 4, a description will be given of the method of employing
the apparatus of the character already described for the purpose of double trans-
mission. Upon the shaft A there is carried a pole-changing device C. Against
the surface of the two series of contact segments c' and c³ respectively, rest two
contact-brushes which are respectively connected, by means of conductors 1 and 2,
with the positive and the negative poles, of the two batteries 01 and 0³. The .
remaining poles of these batteries are connected with the earth at G¹, by means of
a conductor 3. The contact-brush c³ makes alternate contact with the segments of
the two series of contact segments, thereby causing electric impulses of alternating
polarity to be transmitted upon the main line L through an artificial resistance R.
These electric impulses are employed for actuating an escapement device applied
to the receiving instrument.
Two transmitting key-boards F1 and F are respectively located near the
pole-changing device B. These key-boards are constructed in essentially the same
manner as the key-board already described.
The circuit-closing arms are actuated and moved in unison with the shaft A and
pole-changing device C by systems of gearing E' and E². The parts are preferably
so adjusted that for each revolution of the pole-changing device B, each of the
arms will also complete a revolution beneath the keys f. The number of
keys upon each board is preferably equal to the entire number of contact
segments of the circuit-changing devices C.
The keys and the corresponding circuit-closing arms fl are designed to cause
an increase in the strength of current normally transmitted to line whenever it is
desired to print a letter from the corresponding type-wheel of the receiving

page_text: instrument. For this purpose two additional pole-changing devices D¹ and D' are
applied to the shaft A and they revolve in unison with the pole-changing devico C.
The devices D¹ and D' are constructed with contact-segments d¹ and d³ which
respectively correspond to, but are of less width than, the corresponding segments c
of the pole-changer C. The segments d¹ and d of the device D¹ are moreover so
located with reference to the contact brush d³ which is applied thereto, that they
will make contact with that brush at the moment the corresponding segment c of
the device C makes contact with its brush c³. Since however the segments d are
of less width than the contact segments c any particular segment & will have
passed from beneath its brush d³ when only a portion, preferably one half, of the
corresponding contact c has passed its contact brush c³.
The contact segments d¹ and d² of the pole-changing device D' are so located
with reference to the contact-brush d³ applied thereto that they will be brought
into contact therewith at the moment the corresponding segments d¹ and d² of the
pole changing device D' pass out of contact with the corresponding brush & In
other words the parts are so adjusted that during the first half of the contact of
any segment c with the brush c³, a corresponding segment d of the device D¹ will
be in contact with its brush d³, and during the latter half of the contact of the
brush c with the segment c the corresponding contact-segment d. of the pole
changing device D" will be in contact with its contact-brush d³, so that there will
be for each alternate contact of the brush two alternating contacts of the
brushes d³.
The series of contact-segments & are connected with the positive pole of the
battery 0¹ by means of two contact-brushes c and c and the conductors 4 and 5 ;
while the segments d² are connected, by means of the brushes c² and c³ and
conductors 6 and 7, with the negative pole of the battery O". The contact-
brushes are respectively connected through conductors 8 and 9 with the series
of keys f* carried by the two transmitting key-boards F and F. The contact-
arms of these two key-boards are respectively connected, through conductors 10
and 11, with the main line L at a point 12 beyond the resistance R. Two open
branch circuits are thus formed around the resistance R. Either of these circuits
may be completed by means of a key f being depressed at the proper moment.
When such a circuit is completed, an increase in the strength of the current
reaching the main line L will be occasioned by reason of the shunting of the
resistance R, and, as has already been shown, the circuit which is thus completed
will be from the same battery as that which is connected, with the main line at the
same time through the pole changing device C. It will also be understood that the
increase in the strength thus occasioned by the depression of any particular key,
will continue for one half the time occupied by the impulse itself, and it will occur
during the first or the last half of the impulse, accordingly as it is occasioned by a
key upon the key-board F¹ or the board F.
The only remaining point which it is necessary to observe with reference to the
transmitting key boards is that the positions of the arms f' with reference to the
keys of the boards F¹ and F2 respectively, is such that, when one of the arms f'
is passing beneath any one of the keys of the board F', the other arm f¹ is passing
across the space intervening between two keys f" of the board F; so that, what-
ever keys upon either of the boards be depressed, both arms will not simultaneously
make contact with any of these keys. Each arm however will be in a position to
make such contact at the moment the connections of the corresponding branch-
circuit are completed therowith, by means of the corresponding polo-changing
device D¹ or D³.
In Figs. 4 and 6 the keys are shown as arranged in curved radial lines or series,
each series containing four keys. The distance between the radial lines which pass
through the centres of the respective keys of each board are preferably equal, so
that the time occupied by the circuit-closing arm in passing from one key to the
next is the same throughout the board; and, as already stated, the circuit closing
arms are preferably so arranged that when one of the same is passing beneath

page_text: any given key, the other circuit-closing arm is midway between two of the keys
on its board.
The double receiving instrument is provided with two type-wheels T and T',
respectively corresponding to the key-boards F and F. These wheels are mounted
upon the shaft t together with the star wheel m³. The movements of the star-
wheel and thus of the shaft are controlled by means of the anchor-escapement m²
and an electro-magnet M which is provided with an armature m¹ capable of being
vibrated by means of alternating electric impulses transmitted by the pole changing
device C.
The electro-magnet M is in this instance constructed with a set of coils m' which
are wound in the manner usually adopted for producing magnetism of opposite
polarity in the confronting poles of the cores o¹ and o³. The conductor L leads to
one terminal of the coils m of the electro magnet M and the remaining terminal of
these coils is connected with the shaft t'through a brush på resting thereon. Each
set of cores o' and o* is howevor preferably provided with additional coils me and m®
respectively, which are connected with the opposite poles of corresponding local
batteries o³ and o* respectively. The currents from these batteries normally induce
in the cores a given amount of magnetism, and the currents from the main line tend
to increase the strength of the magnetism in one set of cores o³, and to decrease or
Deutralize the amount of the opposite cores o³, or vice versa, accordingly as the -
currents are of one polarity or the other. There will therefore be an excess of
attraction exerted upon the armature m¹ by one set or the other of the cores,
accordingly as the current from the main line is in one direction or the other, and
this excess will cause the soft iron armature to vibrate in a manner well understood.
The movements of the armature thus occasioned permit a stop-by-step movement
of the type wheels, but owing to the construction of the teeth of the scape wheel
and the pallets of the escapement anchor, the movements of the type wheel shaft
will be continuous during the movement of the escapement armature from one
extremity to the other of its vibration.
Upon the shaft t are carried two circuit controlling devices S each consisting of a
series of contact-segments 8' which alternate with intervening non-conducting
segments 83. The segments s' are of such a length that they will be in contact with
a corresponding brush S³ or S', during the revolution of the type wheel, through a
period corresponding to the time during which a corresponding contact segment d
of the transmitting instrument is in contact with its contact brush. The brushes
are morcover so applied to the circuit-controlling devices S' and S³ respectively,
that contact will be made through one and then through the other, but at no time
with both simultaneously. The brushes S³ and S' are respectively connected with
the earth through conductors 13 and 14, in which are included two electro-
magnets P' and P' respectively; the circuit will therefore be completed, during the
revolution of the type-wheel shaft, first through one and then through the other of
the electro-magnets P1 and Ps and the times during which such completion occurs
are made to correspond to the times when the connections of the branch circuits of
the transmitter are completed by the devices D' and D2 with the key-boards F
and Frespectively. If any key upon the board F¹ be depressed the moment the
circuit-closing arm f¹ strikes that key, the connections of the battery O' or O'
which may be connected with the main line through the device C will be completed
around the resistance R, and, at the receiving station, through the shaft t', segment s¹,
brush S and electro-magnet P1, and an impression will be taken from the type-
wheel T corresponding to the key which is dopressed; it being assumed that the
devices have been so placed that the position of the circuit-closing arm with
reference to the keys of its key board, correspond to the position of the type upon
the type wheel with reference to the printing platen.
In like manner any key upon the key-board F may be employed for effecting an
impression of a character corresponding thereto, from the type-wheel T².
The electro-magnets P' and P' are designed to respond only to electric impulses of
increased strength such as are occasioned by shunting the resistance R, and they
•

page_text: •
will therefore act to effect impressions only when a transmitting key has been
struck by the corresponding arm f¹.
It may hero be observed that in order to occasion the desired movement of the
circuit controllers S¹ and S², for the purpose of placing the two electro-magnets P'
and P successively in circuit during each impulse of alternating polarity it is not
only necessary that the type-wheel shaft should be moved, but unless other special
means are provided, it will be also necessary that the typo-wheels themselves shall
change their position during the continuance of each electric impulso In practico
it is desirable to so construct the apparatus that the typo-wheel T, will be in
position to print when the armature m¹ is in a position about midway between tho
confronting cores o¹ and o³, while the type wheel T will be in position to print
when the armature is adjacent to eithor of the cores o¹ or o². It will moreover
appear that the impression must be taken while the type wheel is in motion. This
may be readily accomplished, especially from a wheel of the diameter which it is
proposed to employ in this instrument, namely, about four and one quarter inches,
without difficulty. The armatures n' of the electro-magnets P' and P² are carried
upon levers n², and these levers carry the printing platen n³. When either electro
magnet P is vitalized the corresponding platen will be moved in the direction
indicated by the arrow, and the direction of the curve which it describes will be
the same as the direction of revolution of the wheel. By reason of this construction
no material retardation of the wheel will be occasioned, but on the contrary an
accelerating force will be applied thereto.
Since however it is necessary that the type wheel T shall be in a position more
advanced than that in which it is when an impression is taken from the type-
wheel T, it will be necessary to place the printing platen n³ which is applied to the
type-wheel T in a position correspondingly advanced, so that it may strike the type.
In practice it may be found desirable uuder some circumstances to dispense with
the pole changing devices D1 and D' and to rely merely upon the contact of the
arms with the respective keys f' for obtaining an increase in the strength of
current of the required duration, when it is desired to print. In practice the
duration of the increase of the strength of the current thus obtained would be
sufficiently short to effect the same results as are insured by the use of the pole
changing devices D, it being understood that the circuit closing arins act to force
the keys upward out of their path automatically, thereby breaking contact without
interrupting the movement of the arm.
Referring now to Figs. 6 and 7 a description will be given of a particular form
of circuit-closer which is sometimes employed in connection with the transmitting
instrument.
Upon the shaft A¹ is carried a toothed wheel W₁ which gears with a pinion w¹
carried upon a suitable arbor w². A contact-disc w³ is also carried upon the shaft A¹
and against the opposite surfaces of the same rest two insulated contact-discs w
and wrespectively. Each of these discs are provided with a series of contact-
pins projecting from the surface toward the intervening disc w³. Upon the
revolution of the shaft A' the discs w¹ and w³ are also caused to revolve and the
pins we are successively placed in connection with the disc w³. The relative rates
of revolution of the two discs depends upon the relative sizes of the wheel W' and
pinion w. When seventy-two keys are employed it is preferable to cause the
discs and w to complete six revolutions for each revolution of the disc w³.
There should then be six contact-pins w upon each of the discs w* and w³ so that
for every revolution of the shaft Athero will be seventy two contacts made with
the disc w. The positions of the contact pins w upon the disc w alternate with
those of the pins upon the disc w, and the positions of the discs, and w³
with reference to the intervening disc w³ is such that only one pin is in contact
with the disc w³ at any time. The positive and negative poles of the two
batteries 01 and O2 are respectively connected with the discs wand w³ by means
of conductors 14 and 15, and the remaining poles of those, batteries are connected
with tho earth at G¹ by means of a conductor 16.. The disc w³ is connected by a

page_text: conductor 17 including the resistance R' with the main line L, and alternating
electric impulses are thus transmitted to line in the same manner as described with
reference to the pole changing device C.
For the purpose of completing the shunt-connections around the resistance R*
when it is desired to print, the keys f' are connected by means of conductors 18
and 19 respectively with the main line L at a point 23 beyond the resistanco R*;
while the circuit closing arms f¹ are connected through conductors 21 and 22
respectively with the conductors 14 and 15. The conductors 21 and 22 may
however if desired lead directly to the conductor 17. The contact of either of the
arms with a key f will cause the impulse being transmitted to line to be
increased in strength by reason of the shunting of the resistance R in the manner
already described. The additional pole-changing devices D are in this instance
dispensed with, and the contacts of the arms f with the keys f' are relied upon for
determining the length of the increase in strength of the impulses as already
described.
The advantages secured by this construction of pole-changing device consists
especially in the long surface contact secured between the disc w³ and the
points wº.
The pins we may if desired be mounted upon yielding springs 7 for the purpose
of permitting them to yield slightly when brought in contact with the disc w³.
A form of circuit-controlling device which it may be found convenient to employ
at the receiving station, consists of a disc Y1 (see Fig. 8) carried upon an arbor p³
which is connected through a system of gearing p* with the shaft t. This disc is
provided with a series of contact-segments y', which are sufficient in number to
afford seventy two contacts with each of two contact rollers Y2 and Y³ for each
revolution of the shaft 11. Two contact brushes or rollers Y* and Y³ aro
respectively connected through the electro-magnets P2 and P3 in the manner
described with reference to Fig. 4. These brushes are so located that one is
brought into contact with a conducting segment or contact point at the moment a
corresponding segment is carried out of contact with the other brush.
The operation of this pole changing device is in other respects similar to that
before described.
In the foregoing description the number of type carried by the type wheel, as
also the number of keys in each key-board has been referred to as seventy-two,
and the other related parts have been described as adapted thereto. But the
employment of one hundred and forty four keys upon cach key-board and the
same number of type upon each type-wheel, or in fact any desired number is
contemplated.
Any suitable form of unison device may be employed for securing synchronisin
between the transmitting and receiving instruments.
It is evident that any desired number of instruments may be placed in circuit,
for instance the conductor leading to the earth might be led to and through anothor
instrument, which would operate in the same manner as that described.
No special claim is herein made for the devices and apparatus shewn in Figs. 6. 7
and 8. The circuit closer shewn and described with reference to these figures inay
however be used as an alternative arrangement.
Having now particularly described and ascertained the naturo of the said
invention as communicated to me and in what manner the same is to bo
performed, I declare that what I claim is
1. The combination, substantially as hereinbefore set forth, of a revolving shaft,
two pole changing devices, a main line with which one of said pole-changing
devices is connected, a revolving circuit closing arm, a series of keys so arranged
that said circuit-closing arın passes beneath each of said keys in succession, and
neaus, substantially such as described, whereby said keys may be manually
depressed and automatically raised through the instrumentality of said circuit
closing arm, said arm and said keys serving to connect the second pole-changing
device with the main line.

page_text: 2. The combination, substantially as hereinbefore set forth with a series of keys
arranged in curved series converging toward a common centre, each key being
located in a different radial line from every other key, of a revolving circuit-closing
arm into the path of which any or all of said keys may be projected.
3. The combination, substantially as horoinbefore set forth, with a series of keys
arranged in curved series converging toward a common centre, of a revolving
circuit-closing arm into the path of which said keys may be projected and means,
substantially such as described, for causing any one of said keys when depressed
to remain so depressed until struck by said revolving circuit-closing arm.
4. The combination, substantially as hercinbefore set forth, with a revolving
shaft and a cylinder carried upon said shaft, of an inking pen normally resting on
the surface of said cylinder, an electro-magnet adapted to raiso said pen from said
cylinder, a series of keys, a circuit-closing arm moving with said cylinder and
adapted to complete the connections of an electric circuit through said electro-
magnet when in contact with one of said keys.
5. The combination, substantially as herein before set forth, of a revolving shaft,
a cylinder moving with said shaft, means substantially such as described for
applying a line of non-conducting material to the surface of said cylinder, a series
of keys, a circuit closing arm revolving with said cylinder and means, substantially
such as described for interrupting said line upon said cylinder when said contact
arm strikes against any one of said keys.
6. The combination, substantially as hereinbefore sot forth, with a printing
telegraph instrument, of a moving conducting surface, a pole-changing device
moving therewith, a line of non-conducting material applied to said surface leaving
interposed sections of the same exposed, the distance between any two of which
exposed sections corresponds to the distance through which it is necessary that said
conducting surface should move to cause said pole-changing device to transmit the
requisite number of impulses for revolving the type wheel of said receiving
instrument from the position which it occupies when printing a character
corresponding to the first exposed section, into the proper position to print the
character corresponding to the succeeding exposed section.
7. The combination, substantially as hereinbefore set forth, of a revolving shaft,
a cylinder moving with said shaft two pole-changing devices, means, substantially
such as described, for causing electric impulses of a given strength to be transmitted
through one of said pole-changing devices to the main lino during the revolution
of said cylinder, a transmitting stylus moving over the surface of said cylinder
and acting when in contact with said cylinder to transmit an impulse from the
other of said pole-changing devices having the same polarity as the impulse last
transmitted by the first named pole-changer, but being of shorter duration.
8. The herein before described method of actuating a printing-telegraph receiving
instrument, which consists in causing a series of type to be successively placed in a
position to print, through the agency of alternate electric impulses of a determinate
duration and strength, and in effecting an impression from any type which is thus
placed in position, through the agency of an increase in the strength of the impulse
then being transmitted without prolonging the same, said increase being of less
duration than said impulse, and occurring after the cominencement of the same.
9. The herein before described method of actuating a printing-telegraph receiving
instrument, which consists in causing a series of type to be successively placed in a
position to print, through the agency of alternate electric impulses of a determinate
duration and strength, and in effecting an impression from any type which is thus
placed in position, through the agency of an increase in the strength of the impulse
then being transmitted without prolonging the same, said increase being of less
duration than said impulse.
10. The herein before described method of telegraphy which consists in causing
two or more receiving instruments to be successively placed in circuit with the main
line, through the agency of electric impulses of alternating polarity, and causing

page_text: any or all of said instruments to be actuated during the transmission of any one of
said impulses by a variation in the strength of that impulse.
11. The hereinbefore described method of telegraphy, which consists in connecting
one terminal of a conductor successively with two or more transmitting devices,
transmitting one of a series of alternating electric impulses during each repetition
of said connections, and causing the remaining terminal of said conductor to be
placed in electrical connection with two or more receiving instruments in succession
during the continuance of each alternating impulse.
12. The herein before described method of connecting the respective terminals of
a main line couductor simultaneously with each of a series of transmitting and of a
series of receiving instruments, which consists in connecting said conductor with
each of said transmitting instruments in succession, transmitting a single electric
current during each repetition of said connections, and causing each succeeding
current to be of opposite polarity, and causing the remaining terminal of the
conductor to be placed in connection with the receiving instruments in succession
through the agency of each of said alternating impulses.
13. The combination, substantially as hereinbefore set forth, of a series of
transmitting instruments, a series of receiving instruments, a device adapted to
transmit alternating electric currents to said receiving instruments, and a circuit-
changing device actuated by said alternating currents and adapted to complete the
connections of said main line successively through each of said receiving instruments
during the transmission of each of said alternating currents.
14. The combination, substantially as herein before set forth, of a telegraph main
line, two transmitting devices, two receiving instruments, means for placing said
transmitting devices alternately in connection with one terminal of said main line,
a pole-changing device transmitting an electric impulse for each repetition of the
said connections, two type-wheels actuated by said impulses two press magnets
respectively applied to said type-wheels, and means for completing the connections
of said main line through the coils of said electro-magnets successively during each
of said impulses.
15. The combination, substantially as herein before set forth, of a telegraphic
main line, means for transmitting electric impulses of alternating polarity upon said
main line two transmitting instruments alternately connected with said main line,
which instruments, when actuated, serve to vary the strength of the impulse being
transmitted during a portion of its continuance, and two receiving instruments
which are respectively alternately connected with the remaining terminal of said
main line during the continuance of each alternating impulse.
16. The combination, substantially as herein before set forth, of a main line,
means for transmitting alternating electric impulses thereto, means for varying the
strength of different portions of each of said impulses, and two or more receiving
instruments respectively actuated by such variation.
17. The combination, substantially as herein before set forth, of a main line, a
pole-changing device for transmitting alternating electric impulses upon said main
line, two revolving circuit-closing arms, two key-boards to which said circuit-closing
arms are respectively applied, means for causing the keys of either of said boards
to occasion a variation in the strength of the impulse being transmitted to line
when they are placed in the path of the corresponding circuit-closing arm, and two
receiving instruments respectively adapted to respond to the variations of current
caused by the two key-boards.
18. The combination, substantially as herein before set forth, of a main line, a
pole-changing device adapted to transmit alternating electric impulses to said main
line, an artificial resistance through which said impulses are transmitted, two shunt
circuits around said resistance, and means, substantially such as described, for
completing the connections of either or of both of said shunt circuits at will,
during the transmission of any one of said alternating electric impulses.
19. The combination, substantially as hereinbefore set forth, of a main line, a
battery, a pole changing device adapted to transmit alternating electric impulses

page_text: from said battery upon said main line, an artificial resistance through which said
impulses are transmitted two open branch circuits extending from said battery
ȧround said resistance, means, substantially such as described, for completing tho
connections of each of said branch circuits successively during the transmission of
any one of said alternating electric impulses.
20. The combination, substantially as hereinbefore set forth, with a telegraphic
main line, means for transmitting alternating electric impulses of a given strength
upon said main line, and means for varying the strength of different portions of
cach of said impulses, of two or more receiving electro-magnets, and an escapement
device serving to place said instruments in circuit with said main line successively
during the transmission of a single of said impulses.
21. The combination, substantially as herein before set forth, with a telegraphic
main line, and means substantially such as described, for transmitting alternating
electric impulses upon said main line and for varying the strength of different
portions of each of said impulses, of two receiving electro-magnets, two type
wheels to which said magnets are respectively applied, an escapement-device
actuated by said alternating impulses, and a circuit-controlling device operating to
connect said main line through one or the other of said electro-magnets during the
transmission of each of said impulses.
22. The combination, substantially as herein before set forth, of two electro-
magnets, two printing platens actuated by said clectro-magnets, two type-wheels
to which said printing platens are respectively applied, an escapement device for
said type-wheels and a circuit-controlling device serving to complete a circuit
connection through each of said electro-magnets in succession during the movement
of said escapement device in one direction.
23. The combination, substantially as hereinbefore set forth, of a main line,
means for transmitting alternating electric impulses upon said line, an escapement-
device actuated by said impulses, two type-wheels, two electro-magnets for
respectively effecting impressions from said type-wheels, and a circuit-controlling
device actuated by said escapement device and serving to complete the connections
of said main line through each of said electro-magnets in turn during the
transmission of a single electric impulse.
24. The combination, substantially as hereinbefore set forth, with an escapement
devico, electro-magnets for actuating the same, means for transmitting electric
impulses through the coils of said electro-magnets thereby actuating said escape-
ment-device, two type-wheels, two electro-magnets for effecting impressions
therefrom, which electro-magnets are so adjusted that they do not respond to the
impulses normally employed for actuating said escapement device, incans for
completing the circuit connections from said escapement-magnets to said type
wheel magnets successively during the transmission of a single impulse, and means
for varying the strength of a portion of said impulse when it is traversing the coils
of either of said type wheel magnets.
25. The combination, substantially as herein before set forth, of a telegraphic
main line, two transmitting key-boards, means for placing the same alternately in
connection with said main line, two type wheels and means substantially such as
described, for actuating them, two electro-magnets for effecting impressions from
said type-wheels respectively, and means for completing the connections of said
main line through the coils of said electro magnets alternately and simultaneously
with said transmitting key-boards.