IMPROVEMENTS IN OR RELATING TO ELECTRO-MAGNETIC PRINTING TELEGRAPH APPARATUS
Year: 1883

page_text: "
LETTERS PATENT to William Phillips Thompson of the firm of W P. Thompson
& Boult, Agents for Foreign Patent Solicitors 6 Lord Street Liverpool in the
County of Lancaster Civil Engineer for an Invention of "IMPROVEMENTS IN
OR RELATING TO ELECTRO-MAGNETIC PRINTING TELEGRAPH APPARATUS
A communication to him from Henry Van Hoevenbergh a person resident at
Elizabeth in the state of New Jersey United States of America, Electrical
Engineer.
PROVISIONAL SPECIFICATION left by the said William Phillips Thompson.
at the Office of the Commissioners of Patents on the 28th March 1883.
WILLIAM PHILLIPS THOMPSON, of the firm of W. P. Thompson & Boult Agents
for Foreign Patent Solicitors, 6 Lord Street Liverpool in the county of Lancaster,
Civil Engineer
"IMPROVEMENTS IN OR RELATING TO ELECTRO-MAGNETIC PRINTING
TELEGRAPH APPARATUS," a communication to me from Henry Van Hoevenbergh a
person resident at Elizabeth in the state of New Jersey, United States of America,
Electrical Engineer,
This invention relates to electro-magnetic printing telegraph systems.
It relates both to transmitting and receiving devices for such systems
The principal object of the invention is to secure increased rapidity of operation.
To this end it is sought to reduce to a minimum the number of mechanical
operations performed by the apparatus at the receiving station: thus the type-
wheel is caused to advance normally through successive arcs each subtending two
characters, or in other words, so as to skip one character at each step. When any
one of the characters thus skipped is to be printed, the wheel is arrested on
arriving at the character next in advance of the required character, and a device is
brought into action which mechanically advances the wheel through an arc
subtending one character. This brings the required character into exact position,
and the impression is then taken therefrom
The invention further includes a transmitting mechanism for operating the
improved apparatus at the receiving station thus completing a system both simple
in construction and rapid in operation

page_text: The several consecutive operations of the apparatus at the receiving station are
as follows.
First, The type-wheel is advanced through consecutive arcs each subtending two
characters; secondly it is arrested either in a position to print the desired character
or (when one of the characters normally skipped is to be printed) in position to print
the character next in advance thereof; thirdly if arrested in the position to print
the character next in advance of the required character then it is given a
supplementary movement through an arc subtending one character otherwise this
movement is not imparted to it; fourthly the impression of the character finally
brought into position is taken.
The object of the third of the above mentioned operations, namely that of
imparting the supplementary movement to the type-wheel is to render it practicable
to use the two-letter step movement instead of the usual single letter step.
The several elements of apparatus made use of in this invention are a transmitter,
a receiver and (in conjunction with the latter) a relay. These elements may be
briefly described as follows, it being premised that the various devices employed in
each may in many instances be replaced by well known equivalents, as will be
understood by those versed in the art.
The transmitter and receiver are each provided with a revolving shaft, herein-
after respectively designated as the transmitting and receiving shafts. Each of
these shafts is associated with a driving mechanism, which imparts to it a constant
tendency to revolve in one direction. The organization of the system is such that
the receiving shaft is never liberated to the action of its driving mechanism except
when the transmitting shaft is in motion, and conversely any movement of the
transmitting shaft compels and determines a corresponding movement of the
receiving shaft. This correspondence or synchronism between the respective move-
ments of the two shafts may be brought about through the agency of well known
devices, thus a pole-changer may be actuated by the movements of said transmitting
shaft, so that as often as said shaft completes a definite arc in its revolution it will
cause the reversal of a battery upon the main line, thus successively establishing
alternate positive and negative electrical pulsations throughout the circuit At the
receiving station these alternate pulsations are preferably employed to cause the
two-and-fro movements of an armature between the pole-pieces of electro-magnets.
Each movement of the armature acts through associated mechanism, to cause the
receiving shaft (as well as a type-wheel which is carried thereby) to be advanced
through an arc of its revolution corresponding to that through which the trans-
mitting shaft must revolve in order to effect such reversal of the current on the
circumference of the type-wheel this angle subtends a space sufficient to include
two of the projecting printing type or characters which are symmetrically arranged
one after the other upon and around said circumference; a single revolution
therefore of the transmitting shaft, which reverses the polarity of the line current say
fourteen times, will produce one complete revolution of a type-wheel carrying
twenty-eight characters; hence during each reversal two of said characters will
pass in front of any fixed point which may confront the circumference of the type-
wheel, as for example, the point at which the impression is to be taken.
By successively arresting such a transmitting shaft immediately after each of
the fourteen reversals the receiving shaft may be arrested in fourteen analogous
positions, each particular position being governed by the point of stoppage of the
transmitting shaft.
Every character upon the type-wheel has a corresponding key upon the transmitter,
and these keys may be conveniently classified, with respect to their manner of
operation, into two divisions, hereinafter referred to as the first and second series.
Those in the first series (which comprises every alternate character) perform but a
single function, namely to arrest the transmitting shaft at points in its revolution
dependent upon the particular key operated. The stoppage of the shaft in any
one of these positions causes the arrest of the type-wheel in a corresponding.
position in the manner described. Such stoppage will prolong either a positive or

page_text: negative pulsation upon the line, thus substituting for the previously alternating
current a continuous positive or negative current, as the case may be.
At the receiving station a relay is employed capable of responding to every
pulsation of current whether positive or negative which traverses the line, its
armature being retracted or drawn back by a spring upon each reversal or
interruption of the current.
The forward stroke of the armature-lever of this relay closes the circuit of a
local battery through the coils of the actuating magnet of a mechanism for taking
impressions from the type-wheel, but such mechanism is so adjusted that it will not
respond to currents of short duration, such as the alternating currents which cause
the advance of the type-wheel. It will however respond to the prolonged or con-
tinuous current which is established in the manner just described, when any key of
the first series is depressed. In this manner alternate characters A, C, E, et-cetera
are transmitted and recorded.
The keys of the second series have a double function. Besides arresting the
shaft as in the former case, they cause the opening of the line for the purpose of
interrupting the current.
This causes the armature-lever of the receiving relay to pause upon its back
contact-stop, in which position it closes a local circuit, including two separate
devices; first a device for advancing the type-wheel through the angular space
corresponding to one character-it being understood that in consequence of the
fact that two characters are advanced at every movement of the type-wheel,
whenever one of the keys in the second series is depressed the type-wheel is
arrested in a position to print the character next preceding that desired; hence the
necessity of this device. The second device is the printing mechanism already
described.
The manner in which the printing is effected by the closing of either of said
local circuits is as follows: An armature which is actuated by an electro-magnet
included in both circuits carries a suitable platen, between which and the type-
wheel the paper tape upon which the record is to be printed, is caused by
suitable mechanism to advance, such advancement being preferably effected by
the retrograde movements of said armature-lever.
In the receiving instrument but one type-wheel is required, the same being
provided with a single row of type, disposed in their proper order at uniform
intervals upon its periphery.
In the organization of the electrical circuits but one main line is required.
A manually operated device is provided for the purpose of restoring the unison
between the transmitter and receiver, should the same be disturbed by accident or
otherwise.

page_text: :
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Phillips Thompson in the Great Seal Patent Office on the
28th September 1883.
WILLIAM PHILLIPS THOMPSON, of the firm of W. P. Thompson and Boult, Agents
for Foreign Patent Solicitors, 6 Lord Street Liverpool in the County of Lancaster,
Civil Engineer, "IMPROVEMENTS IN OR RELATING TO ELECTRO-MAGNETIC PRINTING
TELEGRAPH APPARATUS." A communication to me from Henry Van Hoevenbergh,
a person resident at Elizabeth, in the state of New Jersey, United States of
America, Electrical Engineer
This invention relates to electro-magnetic printing telegraph systems.
It relates both to transmitting and receiving devices for such systems.
The principal object of the invention is to secure increased rapidity of operation.
To this end it is sought to reduce to a minimum the number of mechanical
operations performed by the apparatus at the receiving station; thus the type-wheel
is caused to advance normally through successive arcs each subtending two
characters, or in other words, so as to skip one character at each step. When any
one of the characters thus skipped is to be printed, the wheel is arrested on arriving
at the character next in advance of the required character, and a device is brought
into action, which mechanically advances the wheel through an arc subtending one
character. This brings the required character into exact position, and the
impression is then taken therefrom.
The invention further includes a transmitting mechanism for operating the
improved apparatus at the receiving station, thus completing a system both simple
in construction and rapid in operation.
-
The several consecutive operations of the apparatus at the receiving station are
as follows:
First, the type-wheel is advanced through consecutive arcs each subtending two
characters; secondly, it is arrested either in a position to print the desired
character or (when one of the characters normally skipped is to be printed) in
position to print the character next in advance thereof; thirdly, if arrested in the
position to print the character next in advance of the required character, then it is
given a supplementary movement through an arc subtending one character,
otherwise this movement is not imparted to it; fourthly, the impression of the
character finally brought into position is taken.
The object of the third of the above mentioned operations, namely, that of
imparting the supplementary movement to the type-wheel, is to render it
practicable to use the two-letter step movement instead of the usual single
letter step.
The several elements of apparatus made use of in this invention are a transmitter,
a receiver and (in conjunction with the latter) a relay. These elements may be
briefly described as follows, it being premised that the various devices employed
in each may in many instances be replaced by well-known equivalents, as will be
understood by those versed in the art.
The transmitter and receiver are each provided with a revolving shaft, herein-
after respectively designated as the transmitting and receiving shafts. Each of
these shafts is associated with a driving mechanism, which imparts to it a constant
tendency to revolve in one direction. The organization of the system is such that
the receiving shaft is never liberated to the action of its driving mechanism except
when the transmitting shaft is in motion, and conversely any movement of the
transmitting shaft compels and determines a corresponding movement of the

page_text: receiving shaft. This correspondence or synchronism between the respective
movements of the two shafts may be brought about through the agency of well-
known devices, thus a pole-changer may be actuated by the movements of said
transmitting shaft, so that as often as said shaft completes a definite arc in its
revolution it will cause the reversal of a battery upon the main line, thus
successively establishing alternate positive and negative electrical pulsations
throughout the circuit. At the receiving station these alternate pulsations are
preferably employed to cause the to-and-fro movements of an armature between
the pole-pieces of electro-magnets. Each movement of the armature acts, through
associated mechanism, to cause the receiving shaft, (as well as a type-wheel which
is carried thereby.) to be advanced through an arc of its revolution corresponding
to that through which the transmitting shaft must revolve in order to effect such
reversal of the current. On the circumference of the type-wheel this angle
subtends a space sufficient to include two of the projecting printing type or
characters, which are symmetrically arranged one after the other upon and around
said circumference; a single revolution therefore of the transmitting shaft, which
reverses the polarity of the line current say fourteen times, will produce one
complete revolution of a type-wheel carrying twenty-eight characters; hence during
each reversal two of said characters will pass in front of any fixed point which
may confront the circumference of the type-wheel, as for example, the point at
which the impression is to be taken.
By successively arresting such a transmitting shaft immediately after each of
the fourteen reversals, the receiving shaft may be arrested in fourteen analogous
positions, each particular position being governed by the point of stoppage of the
transmitting shaft.
Every character upon the type-wheel has a corresponding key upon the trans-
mitter, and these keys may be conveniently classified, with respect to their manner
of operation, into two divisions, hereinafter referred to as the first and second
series. Those in the first series (which comprises every alternate character)
perform but a single function, namely, to arrest the transmitting shaft at points in
its revolution dependent upon the particular key operated. The stoppage of the
shaft in any one of these positions causes the arrest of the type-wheel in a
corresponding position in the manner described. Such stoppage will prolong
either a positive or negative pulsation upon the line, thus substituting for the
previously alternating current a continuous positive or negative current, as the
case may be.
At the receiving station a relay is employed capable of responding to every
pulsation of current whether positive or negative, which traverses the line, its
armature being retracted or drawn back by a spring upon each reversal or
interruption of the current. The forward stroke of the armature lever of this
relay closes the circuit of a local battery through the coils of the actuating
magnet of a mechanism for taking impressions from the type-wheel, but such
mechanism is so adjusted that it will not respond to currents of short duration,
such as the alternating currents which cause the advance of the type-wheel. It
will however respond to the prolonged or continuous current which is established
in the manner just described, when any key of the first series is depressed.
In this manner alternate characters A, C, E etcetera; are transmitted and recorded.
The keys of the second series have a double function. Besides arresting the
shaft as in the former case, they cause the opening of the line for the purpose of
interrupting the current. This causes the arinature-lever of the receiving relay
to pause upon its back contact-stop, in which position it closes a local circuit,
including two separate devices; first a device for advancing the type-wheel through
the angular space corresponding to one character,-it being understood that in
consequence of the fact that two characters are advanced at every movement of
the type-wheel, whenever one of the keys in the second series is depressed the
type-wheel is arrested in a position to print the character next preceding that

page_text: desired; hence the necessity of this device. The second device is the printing
mechanism already described.
The manner in which the printing is effected by the closing of either of said local
circuits is as follows:-An armature which is actuated by an electro-magnet
included in both circuits carries a suitable platen, between which and the type-
wheel the paper tape upon which the record is to be printed, is caused by suitable
mechanism to advance, such advancement being preferably effected by the
retrograde movements of said armature-lever.
In the receiving instrument but one type-wheel is required, the same being
provided with a single row of type, disposed in their proper order at uniform
intervals upon its periphery.
In the organization of the electrical circuits but one main line is required.
A manually operated device is provided for the purpose of restoring the unison
between the transmitter and receiver, should the same be disturbed by accident or
otherwise.
The invention also comprises certain details of mechanism, the particular subject-
matter claimed being hereinafter specifically designated.
All the improvements are clearly set forth in the accompanying drawings, in
which Fig 1. is a general diagram of the system, especially designed to show
the electrical circuits: Fig. 2. is a plan view of the transmitting instrument, the
cover being partially removed in order to exhibit the interior mechanism: Fig. 3 is
a transverse section of the transmitting instrument showing the construction of
the keys, the transmitting shaft, and the pole-changer carried thereby; Fig. 4. is a
front elevation of the receiving instrument; Fig 5. is a vertical section on the
line X X of Fig. 4, and Fig. 6, a diagram of the electro-magnets and the polarized
armature of the receiving instrument.
Parts appearing in more than one figure are designated by similar reference
letters in each.
The transmitting apparatus may conveniently be regarded as composed of four
divisions. The first of these effects the transmission of the alternate positive and
negative pulsations, by which the step-by-step rotation of the type-wheel is
produced, the latter passing at each step through an angle subtending two
characters. The second establishes the conditions necessary to cause an impression
to be taken from the type-wheel at the receiving station. The third determines
the specific character of the impression, that is to say, which of said two
characters shall be imprinted. The fourth provides for re-establishing the unison
or synchronism between the transmitter and the receiver in case the same is
destroyed.
Considering the first of these divisions:-The transmitting battery 1 is connected
by its positive or copper pole by way of the line 2, binding-screw 3, and line 4,
contact-spring 5 (see Fig. 2), contact-ring 6, line 7, flexible spring 8, arm 9, and
shaft 10, with the lower circuit-wheel 11, of a pole-changing apparatus, carried by
said transmitting shaft 10, and shown in vertical transverse section in Fig. 3.
This pole-changer is composed of two metallic circuit-wheels 11 and 12, which are
insulated from each other, the shaft 10 being in electrical union with the lower
circuit-wheel only. The negative or zinc pole of the main battery 1 is connected
by way of the line 13, binding-post 14, wire 15, and pressure contact-spring 16, to
the upper-circuit-wheel 12 of the pole-changer. It will thus be understood that
the circuit-wheels 11 and 12, while free to rotate with the shaft 10, constitute at
all times, the positive and negative electrodes respectively of the battery 1. The
periphery of each of these circuit-wheels is provided with a series of seven notches
or recesses of equal length. The length of each recess is approximately equal to
that of the section of the circumference projecting between two consecutive
recesses. The angular position of the circuit-wheels upon the shaft with reference
to each other, is such that every indentation of one is opposite to a projection
of the other. Against the perimeters of these circuit-wheels the contact-springs 18

page_text: and 19 press by their own resiliency, and to these springs are attached, at
points 20 and 21 respectively, the terminals of the line wire and of the ground or
return wire. As the pole-changing circuit-wheels perform one revolution, the
spring 18 will impinge seven times against the perimeter of the wheel 11, and
seven times against that of the wheel 12. Similarly the spring 19 will, when the
spring 18 impinges upon the wheel 11, itself impinge upon the wheel 12, and
when the spring 18 impinges upon the wheel 12 it (the spring 19) will impinge
upon the wheel 11.
In consequence of this action, there will be transmitted over the main line
fourteen electrical pulsations during each revolution of the transmitting shaft,
seven of which will be positive, and seven negative. In practice any desired
number of separate indepenent lines, each provided with its own receiving instru-
ment, may be operated from one transmitting station by making use of as many
separate commutators or pole-changers such as described, as there are independent
lines to be operated: and by mounting all these pole-changers upon a single shaft
which may be of any appropriate length and which will thus actuate all the lines
in unison.
The mechanical instrumentalities for imparting motion to the shaft 10 and to
the pole-changer hereinbefore described, may be of any suitable character. It has
been deemed preferable in the present instance to employ a clock-work mechanism,
partially shown in Fig. 2, actuated by a weight the sustaining cord of which is
wound about the drum 22. The system may be wound up by applying a suitable
key to the drum shaft in a well known manner. A constant tendency to revolve
is thus imparted to the shaft 10, which will take effect whenever the latter is
released by mechanism hereinafter to be described.
The second and third divisions of the transmitting apparatus, namely, that
which establishes the conditions necessary to cause an impression to be taken from
the type-wheel at the receiving station, and that which determines the specific
character of the impression, may be described conjointly as follows:-A key-
board 25 is located upon the upper face of the case in which the entire trans-
mitting mechanism is contained. The keys are arranged upon the key-board in
two concentric circular rows each comprising fourteen keys. The characters made
use of in the present instance, and which are sufficient for the general purposes for
which this instrument is designed, are the letters of the alphabet, the character (&)
and the period (); but it will be understood that the description herein of
mechanism for transmitting 28 different signals is not to be construed in prejudice
to any application of the same to a greater or less number of characters. The
construction of the several keys is illustrated in Fig. 3. Each key consists of a
vertical pin 26 terminating in a knob or button 27 at the top, by means of which
it may conveniently be depressed by the finger of the operator, and it is also
provided with a helical spring 28 surrounding its shaft for raising it to its normal
position when released. These keys may be depressed through a short space,
preferably an eighth of an inch, so that their lower ends will slightly project from
the under surface of the lower base plate 29. This will bring them into the plane
in which the projecting arm or cam 9 (rigidly and electrically connected to the
shaft 10 at the point 30) travels. In this manner, by depressing any one of the
outside series or row of keys the traveling arm 9 may be arrested in any one of a
series of fourteen positions, thereby prolonging the pulsations of current which
traverses the circuit at the time of the arrest. Similarly the depression of any one
of the inner series or row of keys serves to arrest the travelling arm in any one of
fourteen other positions intermediate to those mentioned in connection with the first
series.
By the depression of any one of the inner series of keys two operations are
performed, namely, first: the travelling arm 9 is arrested in a position depending
on the key depressed, and secondly, the battery is detached from the line, in the
following manner: As before described, the circuit-wheel 11 of the pole-changer is
connected with the positive pole of the battery 1, the current passing through the

page_text: flexible spring 8 and arm 9, normally in electrical contact at the point 39. When
one of the inner series of keys is depressed and the flexible spring 8 comes in contact
therewith, the consequent pressure is sufficient to separate the contact-points and
open the circuit.
Thus by the operation of the proper keys a pause of the transmitting shaft may
be made to take place during which there will be either a positive current, a
negative current, or no current whatever upon the line, according to which key is
depressed Any one of these conditions serves to actuate the impression device at
the receiving station, while the pauses in which there is. no current upon the line,
serve to operate the determining device as well.
The fourth division of the mechanism at the transmitting station, or that
operating to re-establish the synchronisin or unison when disturbed, consists of an
additional key operated by the switch 35, which serves to arrest the shaft arm 9 in
the same position as does the key representing the zero character (.). When this
switch is moved against the stop 36 the projection 34 is brought into the path of
the arm 9, and as this projection is not provided with means for automatically
returning it to its previous position (as in the case of the other keys,) it remains there
until manually returned to the point 38 as shown in the figure. When the instru-
ment is not in operation this switch should be left upon the stop 36. This condition
will enable any one at the receiving end to bring his instrument into unison with
the transmitter in a manner hereinafter to be described when the receiving
mechanism is considered.
The apparatus at the receiving station may, like the transmitting apparatus, be
conveniently regarded as embracing four divisions. The first controls the inter-
mittent rotation of the receiving shaft and type-wheel; the second produces the
impression upon the paper tape and feeds the latter forward with each impression;
the third determines the particular character of the impression, that is to say,
whether it shall be one or other of two consecutive characters upon the type-wheel,
and the fourth is a device for establishing the synchronism or unison of the type-
wheel with the transmitting apparatus in case they are thrown out of corre-
spondence by accident or otherwise.
The first of these divisions is actuated by the alternating electrical pulsations
established upon the main line by the rotation of the transmitting shaft. These
currents traverse the coils of the electro-magnets 48 and 49. To understand the
winding of these electro-magnets reference is made to Fig 6. in which the helices
surrounding the cores of the electro-magnets are represented by a single convolution
so as to show clearly the direction of the winding. The continuous conducting
wire 40, which is included in and forms part of the main line, is wound helically
around these cores successively in the manner illustrated in the figure. By
tracing this wire in the direction indicated by the arrows it will be observed that
it is wound in one direction around the core 50 of the electro-magnet 48, and
in the opposite direction around the other core 51 of the same: it then passes to
the electro-magnet 49 being wound around the core 52 in a direction opposite to
that last mentioned, and lastly the direction is again reversed in passing around
the core 53 of the electro-magnet 49. If no current traverses the liue 40, the
armature 54 will remain unattracted, but when a current of one polarity traverses
the line both poles of the armature 54 will be simultaneously attracted toward one
of the electro-magnets, and repelled by the other, and the armature will accordingly
move toward the attracting magnet: and when a current of opposite polarity
traverses the circuit exactly the reverse effect will take place. Hence when
alternate pulsations of positive and negative electricity are transmitted through
both electro-magnets (these being included in the same circuit) the armature 54 is
caused to vibrate to-and-fro. If however the current traversing the line 40 be
interrupted, the armature 54 being in contact with one or other of the poles of the
electro-magnets 48 and 49, will remain in such contact. The conditions which
actually occur upon the line 40 are as described, either a positive current, a period
of rest succeeding a positive current, a negative current, or a period of rest

page_text: succeeding a negative current. Under the influences of such conditions the
armature 54 will be actuated by each current, remaining inactive during the said
periods of rest.
The armature 54 is carried by an armature-lever 55 (see Fig. 1) fixed to a rock-
shaft 56, and carrying an anchor escapement 57, provided with pallets 58 and 59,
which alternately engage with the teeth on the opposite side of the scape-wheel 60.
The latter is mounted upon the arbor 61, which tends to rotate continuously in
the direction indicated by the arrow, being impelled by a train of wheel-work,
actuated by the descent of a weight, whenever the escapement permits. The
arbor 61 carries, in addition to the scape-wheel 60, another wheel 65, having
bevelled teeth, and also a type-wheel 66, said wheels being rigidly connected with
each other but carried loosely upon a sleeve on the arbor 61, from which arbor
projects a pin 67 entering a slot 68 in the wheel 65. This slot is of sufficient
length to admit of a slight parallel revolution of the wheels 55 and 56 inde-
pendently of the arbor C1. Longitudinal displacement of the wheels 65 and 66
upon the arbor 61 is prevented in one direction by the stop 69 (see Fig. 5) and in
the other by the stop 70. A spring 71, one end of which is attached to the back
of the wheel 65 while the other end bears against the pin 67, tends to maintain
the wheel 65 in such relation to the arbor 61, that the pin 67 will take the
position in the slot 68 which is shown in Figs 1 and 5.
It will therefore be understood that with every impulse traversing the electrical
circuit 40, the armature 54 and anchor escapement 57 will be actuated, thereby
liberating the shaft of the escapement wheel 60, the movement of which will be
communicated by means of the pin 67, to the type-wheel 66.
There are 28 characters upon the circumference of the type-wheel, symmetrically
disposed one after the other at equal distances apart and respectively corresponding
to the twenty-eight keys at the transmitting station. With every movement of
the armature the type-wheel advances one-fourteenth part of a complete revolution,
or in other words, through an angle subtending two of said characters.
The second division of the receiving instrument, namely that which produces
the impression upon the paper tape, may be described as follows. The current
which traverses the electro-magnets 48 and 49 passes by the wire 41 to the relay
magnet 42, and by return wire 143, or earth circuit in lieu thereof, back to the
transmitting instrument. Every electrical impulse therefor that traverses the main
circuit 40, will actuate the electro-magnet 42, causing it to attract its armature 43,
thus bringing the armature-lever 44 against its front contact-stop 45. Every
cessation of the current will liberate the armature-lever 44 to the action of the
retractile spring 46, and cause it to fall upon its back contact-stop 47. When against
the front contact-stop 45 a local circuit is closed which may be traced as follows.
From the positive pole of the battery 70 by wire 71 to contact-stop 45, armature-
lever 44, line 72, electro-magnet 73, and line 74, to negative pole of the battery 70.
This local circuit will therefore be closed in correspondence with every pulsation
irrespective of polarity that traverses the main line 40. When in contact with its
back stop 47, the armature-lever 44 will close a second local circuit which also
includes the electro-magnet 73 and which may be traced as follows. From the
positive pole of the battery 90 via, the line 91, contact-stop 47, armature-lever 44,
line 72, electro-magnet 73, line 74, battery 70, line 71, line 92, electro-magnet 93,
line 94, to negative pole of battery 90. The pauses of the armature-lever 44 upon
its contact-stops, are either of very short duration when produced by the alternating
current caused by the revolution of the transmitting shaft, or they are comparatively
long pauses produced in the manner described, by the depression of the keys of the
transmitter. The spring 78 is so adjusted that the printing mechanism shall be
operated by currents of long duration only, in which case the electro-magnet 73.
will attract its armature 74, which is carried by the lever 75, the latter being
fulcrumed at 76 and balanced by the counterpoise 77, so that said armature-lever
is moved in opposition to the force of the retractile spring 78. Normally the
armature-lever 75 rests upon its back contact-stop 80, and when actuated by the

page_text: vitalization of the electro-magnet 73 it ascends a sufficient distance to bring the
platen 81, carrying the band or tape of paper 82, into contact with the type-
wheel 66. The paper-feeding mechanism is actuated in a well-known manner by
the retrograde movement of the printing lever 75 after the impression has been
taken. This mechanism consists of a cam 100, carried at the extreme end of the
lever 75, fulcrumed at 101, and provided with a shoulder 102 and a spring 103,
extending from the lever over said shoulder and maintaining said cam against a
serrated portion of the circumference of the feed-wheel 104. A second friction
wheel 105 rotates loosely upon the arbor 106, the latter being carried by the
lever 107 fulcrumed at 108, and constantly depressed by spring 109, thus keeping
the friction-wheel 105 in close contact with the feed-wheel 104. The paper tape
is directed in its path by guide-pins carried by the lever 75. The type-wheel
receives its ink from an ordinary inking roller 140 placed immediately above it.
The third feature of the printing mechanism, namely, the device for determining
the particular character, that is to say, which of two adjacent characters shall be
printed, is actuated whenever the current of the main line is interrupted, which
occurs whenever any one of the inner row of keys at the transmitting station is
depressed. The local circuit which is closed at the back contact-stop 47 of the
armature-lever 44, has already been traced. It includes the batteries 70 and 90
and the electro-magnets 73 and 93. The magnet 73 is thus again actuated to
perform the office of printing as already explained. The function of the magnet 93
is as follows: Its attraction is exerted upon the armature 111 actuating the
armature-lever 112, fulcrumed at 113, and normally kept at a distance from the
magnet by a spring 114, adjustable by the screw 115, best seen in Fig. 4. The
excursion of the armature 112 is determined by the adjustment screws 116 and
117, the former limiting its forward motion toward the magnet and the latter its
backward motion away from the magnet. The armature-lever 112 articulates at
118 with the bent lever 119 fulcrumed at 120, upon an arbor carried by and
running parallel to the armature lever 75. To permit the rise and fall of said bent
lever 119 the articulating arbor 118 traverses a slot in the end of the lever 119, so
that the latter may be operated by the motions of the lever 112 regardless of its
vertical position. The end of the bent lever 119 is bevelled as shown at 121,
Figs 4 and 5. Let it be assumed that the magnet 93 is not actuated, when the
armature 75 is elevated, the lever 119 will ascend in front of the bevelled toothed-
wheel 65. If on the contrary both magnets 73 and 93 are simultaneously actuated
the lever 119 will be moved into the vertical plane in which is situated the
wheel 65. The end 121 of said bent lever will impinge upon the bevelled surface
of the tooth immediately above and cause the wheel 65 as well as the type-wheel
which is rigidly connected thereto, to be advanced through the angle, subtending
one character, said advancement being limited by the excursion of the pin 67
within the slot 68.
Of the two devices thus actuated by reason of the contact of the relay
armature-lever 44 with its back stop, the first to perform its allotted function is
the determining device, for the determining lever 119 is carried by the printing
lever 75 and by the time that the latter has been sufficiently elevated to take an
impression the determining lever has already performed its function.
The fourth feature of the receiver is the unison device. It consists of a lever or
detent 130, swinging under slight friction between the stops 131 and 132. It
carries at one end a trip 133, which when said lever is in contact with the
stop 132, extends into the path of the cam 134 projecting from the arbor 61. By
operating the lever the type-wheel may thus be arrested in that position in which
it will print the zero character (.). As before described, the transmitting shaft
always starts from the corresponding or zero point of the key-board.
Reviewing the above description, when the first key (A) is depressed, a positive
current is sent to line, the relay 42 is actuated, the magnet 75 is vitalized but not
the magnet 93, hence the character brought into position upon the type-wheel will
also be (A). If now the second key (B) is depressed the current will be

page_text: interrupted, both the magnet 73 and 93 will be actuated, and through the agency
of the latter the type-wheel will be advanced through the space of one letter prior
to the operation of the printing, and hence the letter (B) will be printed. On
depressing the third key (C) another current will be sent to line of opposite
polarity to that previously transmitted, the escapement-wheel will accordingly be
advanced one tooth, the magnet 73 only will be actuated and the letter (C) will be
printed. Depressing now the fourth key (D) the current is interrupted, both the
magnets 73 and 93 are actuated, and through the agency of the latter the type-
wheel is advanced through the space of one letter prior to the printing, hence the
letter (D) will be printed. If however succeeding letters are not to be printed
but letters are chosen at random it will be understood that as often as the shaft-
arm 9 passes an outer key, so often is the escapement operated, and so often is
the type-wheel advanced through the space of two letters; hence whatever key
is depressed on the key-board the letter which it represents is impressed upon the
paper.
Among the advantages arising from the improvements herein set forth, the most
important is that of rapidity of transmission. It will be understood by those
skilled in the art that the same pulsation that in other systems ordinarily causes a
single character of the type-wheel to be advanced, in this invention causes the
advancement of two characters, thereby enabling the instrument to transmit 300
words per minute, with no greater rapidity of electric pulsation than has been
heretofore required for transmitting 150 words.
Having now described the nature of this invention, and the manner in which the
same is to be performed, as communicated to me by my foreign correspondent, I
would have it understood that I claim :-
1st. The combination, substantially as hereinbefore set forth, of two series of keys,
mechanism operated by the depression of any key in one series to prolong the
duration of the current traversing the line at the instant of operation irrespective
of the polarity of said current, and mechanism operated by the depression of any
key in the other series for withdrawing whatever current is then traversing the.
line.
2nd. The combination, substantially as herein before set forth, of the revolving
shaft of a transmitting instrument; a pole-changer carried thereby for inter-
mittently reversing the current upon the main line; a series of keys for
arresting the motion of said transmitting shaft at predetermined points in its
revolution, thereby prolonging the particular current pulsation traversing the
line at the instant of arrest, and a second series of keys for arresting said shaft
at other predetermined points and simultaneously opening said main line.
3rd. The combination, substantially as hereinbefore set forth, of a system of circuits
conveying an electrical current, a pole-changer for intermittently reversing
said current, a series of keys, each serving when operated to arrest the action of
said pole-changer, thereby instituting a continuous current in said circuit, and a
second series of keys, each serving when operated to withdraw said current by
interrupting said system of circuits.
4th. The combination, substantially as herein before set forth, of a revolving shaft,
an arm or cam projecting laterally from said revolving shaft, a system of
contact-points carried by said arm, a battery, the circuit of which is completed by
the contact of said points, and a series of keys for simultaneously arresting the
motion of said arm and separating said contact-points for the purpose of
interrupting the circuit of said battery.
5th. The combination, with a type-wheel shaft, a type-wheel normally moving
therewith, and mechanism for advancing said type-wheel shaft through successive
arcs, each subtending two characters upon the circumference of said type-wheel,
of a device for mechanically imparting a supplementary movement to said
type-wheel independent of the movements of said shaft, substantially in the
manner described.

page_text: •
6th. The combination of a shaft, a sleeve movable thereupon, a type-wheel rigidly
carried by said sleeve, a bevelled-toothed wheel also rigidly carried by said
sleeve, and yielding mechanism, substantially as described, whereby the movements
of said shaft are communicated to said type-wheel while permitting the movement
of said type-wheel independently of said shaft through an arc subtending a single
character.
7th. The combination with a type-wheel and bevelled-toothed wheel connected
together and flexibly mounted upon a shaft substantially in the manner
described, of a printing-lever, a subsidiary lever articulating with said printing
lever and moving therewith, an armature-lever articulating with said subsidiary
lever, and an electro-magnet actuating said armature-lever to move said subsidiary
lever into the plane of said bevelled-toothed wheel.
8th. The combination, substantially as hereinbefore set forth, of a type-wheel
normally advancing the distance equivalent to two characters at a time, a printing
mechanism capable of producing the impression of one character at a time, a
device for still further advancing the type-wheel through a distance equivalent
to one character, and a relay vitalized by currents traversing the main line for
setting in action said printing device together with said device for still further
advancing the type-wheel.
9th. The combination, substantially as herein before set forth, of a relay, two
local circuits respectively closed by said relay upon its back and front stops, an
electro-magnet for actuating a printing mechanismn included in one of said circuits,
and an electro-magnet acting through intermediate mechanism to advance said
type-wheel through a definite are included together with said printing magnet in
the other circuit.
10th. The combination, substantially as herein before set forth, of a relay armature-
lever making both long and short contacts upon each of the limiting stops
between which it plays, and two local circuits closed upon said stops, one including
the printing electro-magnet and the other including said printing electro-magnet
and an electro-magnet for mechanically advancing the type-wheel, the armatures
of both of said magnets being adjusted to respond to the said long contacts only.
11th. The combination, substantially as herein before set forth, of mechanism
operated by the depression of alternate transmitter keys for arresting an ad-
vancing type-wheel shaft in such position that the type-wheel carried thereby
presents for impression the character next in advance of that represented by the
key depressed, mechanism for still further advancing said type-wheel independently
of said shaft for the purpose of bringing the particular character represented by
the key depressed into printing position, and printing mechanism.
12th. The combination, substantially as hereinbefore set forth, of the following
elements actuated by electrical currents and controlled by the depression of
alternate transmitter keys, namely, mechanism for advancing the type-wheel to a
position such that the character to be printed is in the neighbourhood of the
printing mechanism, mechanism for still further advancing said type-wheel
independently of its shaft for the purpose of bringing said character into exact
position for printing, and printing mechanism.
In witness whereof I the said William Phillips Thompson have hereunto set y
hand and seal this twenty sixth day of September in the year of our Lord one
thousand eight hundred and eighty-three.
WP. THOMPSON
(L.S.)