Improvements in Electric Telegraphic Systems.
Year: 1897

page_text: Date of Application, 15th Mar., 1897
Complete Specification Left, 13th Dec., 1897-Accepted, 15th Mar., 1898
PROVISIONAL SPECIFICATION.
Improvements in Electric Telegraphic Systems.
(A Communication from ALBERT C. CREHORE, Professor of Physics, of Hanover,
County of Grafton, State of New Hampshire, United States of America, and
GEORGE O. SQUIER, Second Lieutenant in the U.S. Army, Stationed at Fortress
Monroe, Virginia, United States of America.)
I, WILLIAM LLOYD WISE, of 46, Lincoln's Inn Fields, in the County of London,
Consulting Engineer and Chartered Patent Agent, do hereby declare the nature of
this invention to be as follows:
This invention relates to a method of and apparatus for transmitting intelligence
over an electric circuit at high speed.
High speed systems of telegraphy, as heretofore organized and operated have a
limited capacity owing, among other things, to the character of the receiving
instruments employed, to the disturbances and mutilations of the signals ex-
perienced when the attempt is made to transmit a succession of distinct electric
pulses or currents at a rapid rate, or to the difficulty of maintaining exact
synchronism between transmitting and receiving apparatus.
The object of the present invention is to provide a system of telegraphy which
shall be free from many of the difficulties or disturbances hitherto experienced
with high speed telegraphs and which are important factors in limiting the speed
of transmission, to thereby produce a system which shall be of extremely high
speed capacity and to secure these results by a system which shall be simple in
principle, construction and operation.
In carrying out this invention a periodically varying electric current is used
whose pulses recur at any desired rate, preferably at a very rapid rate, and impress
upon such current the characters of any desired code, by systematically cutting out
or suppressing in whole or in part definite pulses of said current in predetermined
order or relation according to the code selected. The periodically varying current
having such impressed characters operates upon any suitable receiving instrument
adapted to respond to and make a record or mark for each electric pulse, thus
providing a visual record of the varying current which shows the order or relation
of the several repressed or transmitted pulses to one another and may be therefore
read according to the selected code.
The periodically varying current may be alternating in character or polarity or
may be continuous or of one polarity and vary only in tension or amount and the
pulsations may be more or less abrupt in their changes, or considered graphically
as a series of waves the current may be either a sinusoidal current curve such as
would be developed by an ordinary dynamo generator of alternating currents or
may depart in greater or less degree from such curve as would be the case where
the strength of current rises with a greater degree of abruptness from zero or its
least strength to its maximum or greatest strength. Be it, therefore, understood
that this invention includes all characters of rapidly varying and periodical currents
of a pulsating, intermittent, undulating, vibrating, alternating or other character.

page_text: In the preferred form of the invention, however, a sinusoidal current is employed,
preferably an alternating one, and an alternating current when employed in the
manner and for the purposes hereinafter described is claimed as of this invention.
The pulses of current may be suppressed in the desired order or relation by any
suitable means but by preference there is employed for this purpose a circuit
controlling device of any proper kind as hereinafter described.
Another feature of this invention consists in using a rapidly varying current
rising and falling in strength from zero and generated by any desired means as by
an alternating current dynamo and suppressing sinuses of said current of any
desired number or at any desired time by any suitable means as by a circuit
breaker and maker adjusted or timed to break and make the circuit at exact times
of zero propagation or flow of current waves or pulses.
This method of dealing with an alternating current employed for any purpose
or in any system of telegraphy. or with any form of receiver is claimed broadly as
of this invention. Heretofore in the art the stoppage and resumption of flow of
such current has been effected without reference to the condition of the individual
wave, thus giving rise to sparking or other disturbance. By this plan sparking is
absolutely avoided and the stoppage and resumption of flow take place in an
absolutely uniform and exact manner. It is obvious that the stoppage of the flow at
the exact time stated possesses in itself valuable advantages whether the flow be
resumed or not at a similar point and therefore, claim is here laid broadly to this
method of interrupting the continuity of flow of a rapidly varying current which
changes at each undulation from zero and back to zero.
Another feature of this invention consists in the combination with a generator of
alternating currents, of a recorder of cach alternation comprising means for pro-
ducing a polarized beam of light, means for rotating the beam by each pulse away
from the position of darkness produced by an analyzer, and a photographic recorder
of each spot or pulse of the rotated beam corresponding to each alternation. This
device enables one to make a graphic record of the successive pulses or waves of
an alternating current of any rate or period, each pulse whether negative or positive
being noted in the same way owing to the fact that a rotation of a polarized beam
in either direction from the position of darkness, as produced by the analyzer, will
cause it to become visible.
As a receiver or recorder for use in carrying out this invention, it is preferred to
utilize the devices described in British Patent No. 14,888, under date of August 6th,
1895, since it is theu capable of operation at very high speed owing to the fact
that the recording element, to wit: a polarized beam of light, is without mass
and obeys instantly the changes in the electric circuit controlling it.
The term semi-cycle is used herein in the ordinary sense to mean the portion
of a current wave extending from at or about one zero point to at or about the next
succeeding zero point.
In describing the invention reference is had to the alternating current, though it
must be expressly understood that the invention is not hereby limited to the
employment of the alternating current, since as will be hereinafter shown, it may
be operated by or over any varying current having clearly defined periodic
variations, preferably a uniformly varying one.
A receiver of this sort responds instantaneously to changes in the transmitting
current. In fact so sensitive is it, that it clearly indicates the frequency of the
alternating current, the light affecting the sensitized plate during each semi-cycle
and being cut off during the interval between semi-cycles.
From the fact that in the alternating circuit there is a cessation of current
between each semi-cycle, it follows that to cut out or suppress one or more complete
semi-cycles will not affect the preceding or succeeding ones nor in any way hinder
the progress of the current over the circuit. This has been clearly demonstrated
in the experiments on this system. It is also clear that one or more complete semi-
cycles may be suppressed without producing any sparking whatever.

page_text: From the fact that in an alternating circuit there is a cessation of current
between semi-cycles, it follows that, if the circuit is interrupted at the instant
when the current is naturally zero, the current will remain zero as long as the
circuit remains broken, and with means for controlling the time of breaking the
circuit, a single half period or semi-cycle, or any number of half periods may be
omitted at will. One of the reasons for interrupting the circuit when the current
is naturally zero is the very practical one involving the question of sparking at
the brushes. If the current is zero when the circuit is broken, then no spark
appears at the break.
For the sake of convenience in illustration, the Continential code of telegraphy is
is followed and one semi-cycle suppressed for a dot and two successive ones for a
dash. Dots and dashes are separated by one semi-cycle, letters by two, words by
three and sentences by four or more.
A simple transmitter for use in this system may consist of a perforated tape
moved in synchronism with the current generator and a pair of contacts between
which circuit it made and broken by the tape. This tape may be prepared in any
perforating machine capable of producing the perforations at regular intervals and
of making the spaces between them of exact multiples of the perforations and
intervals. Where two or more space perforations come together, as between letters
and words, the divisions of insulation between them may be omitted since said
divisions come at the zero point between successive semi-cycles and the same effect
will be produced upon the photograph in either instance.
In this system therefore, the material of the tape is used to suppress sinuses
and the perforations provide for the propagation of those sinuses which are to
cause the light to pass to the sensitive plate or film. A blank portion equal to one
perforation will cause one sinus to be suppressed, and the suppression of one sinus
means a dot upon the photograph and the suppression of two in succession means a
dash. Then the dots, dashes, letters, etc., being separated in the tape by perforations
they will be separated upon the photograph by light-affected spots or what are in
effect photographs of the transmitted sinuses.
To produce this result it is necessary that the tape, after being perforated as
above described, be fed at a speed exactly corresponding to the succession of semi-
cycles of the current of the line, so that the parting and meeting of the contacts
may occur uniformly and at the zero points of the wave.
This uniform speed may be obtained in many ways, but the most accurate way
of obtaining it is directly from the axle of the alternating generator furnishing the
line current or from one run in unision therewith.
The contacts co-operating with the tape may consist of a wheel and brush or of
two brushes which are placed at an angle to the tape and meet through the
perforations therein. These brushes may be made adjustable longitudinally of the
tape to provide for placing them in such a position in relation to the perforations
that they shall meet and separate on the edges of the perforations at the zero points
in the current and so produce a clear record and prevent sparking.
The receiver may be operated directly by the line circuit from the generator or
it may be operated in a circuit derived from the line circuit through any suitable
transformer. In this way any number of receivers may be operated from the same,
main line. With this system, from a trans-continental line, the same message can
readily be delivered at receivers all along the route. Further in. the operation of
the system, the interrupter has been placed in the secondary circuit with the
receiver as by putting a transformer across the mains.
It has thus been shown how readily intelligence can be transmitted by. this
system. The rapidity with which the transmitter can operate is limited only by
the limit in the frequency of alternations in the circuit. The limit to the frequency
of interruptions of the ray of light in the receivers described has not been reached
with the maximum rate of alternations which have so far been available. The
limit of the receiver then, depends solely upon the sensitiveness of the photographic
tape and that is of a sufficiently high degree to insure the reception of intelligence

page_text: with a rapidity exceeding by many hundred times that of the present telegraph or
telephone.
In operating this system the perforated. tape is fed to the transmitter which
suppresses semi-cycles of the line current in the required number and order in
accordance with the code used. The transmitted semi-cycles act in the receiver to
allow the beam of light to reach the rapidly moving sensitive tape in a manner to
reproduce the semi-cycles both as to duration and intervals. The sensitive tape is
fed through the developing and fixing baths and issues bearing a legible message.
It must be borne in mind that the above description is simply for the purpose of
disclosing the principle of this invention; that the details of the transmitter may
be developed in various other ways, and that the means and manner of preserving a
record of the message at the receiver may be greatly varied.
In this system as disclosed, the code adopted has been applied by suppressing
or cutting out portions of the current to represent the characters and allowing
the transmission of current to produce the spaces. Obviously portions of the
current may be suppressed to represent spaces and the portions of
current transmitted be made to produce the characters. It is apparent that having
established a way of photographically representing the natural periods of a
periodically varying electric current and a means for suppressing determinate
periods of current at will any dot or dash code that may be devised can be readily
imposed upon the current.
Dated this 15th day of March 1897.
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.
(A Communication from abroad by PROFESSOR ALBERT C. CREHORE and
LIEUTENANT GEORGE O. SQUIER.)
I, WILLIAM LLOYD WISE, of 46, Lincoln's Inn Fields, in the County of London,
Consulting Engineer and Chartered Patent Agent, do hereby declare the nature of
this invention and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement:-
-
This invention relates to a method of and apparatus for transmitting intelligence
over an electric circuit at high speed.
High-speed systems of telegraphy as heretofore organized and operated have a
limited capacity owing, among other things, to the disturbances and mutilations of
the signals occurring when the attempt is made to transmit a succession of distinct
electric pulses or currents at a rapid rate, or to the difficulty of maintaining exact
synchronism between transmitting and receiving apparatus.
The object of the present invention is to provide a system of telegraphy which
shall be free from many of the difficulties or disturbances hitherto experienced
with high-speed telegraphs and which are important factors in limiting the speed
of transmission, to thereby produce a system which shall be of extremely high-
speed capacity and to secure these results by a system which shall be simple in
principle, construction and operation.
To this end a periodically varying electric current is used whose pulses recur at
any desired rate, preferably at a very rapid rate, and the characters of any desired
code are impressed upon such current by systematically cutting out or suppressing
in whole or in part definite pulses of said current in predetermined order or relation

page_text: according to the code selected, by means of a prepared message such as a tape which
is run at a speed synchronous with the devices which develope the pulses. The
periodically varying current having such impressed characters operates upon any
suitable receiving instrument adapted to respond to and make a visual record of
the varying current which shows the order or relation of the several repressed or
transmitted pulses to one another and may therefore read according to the selected
code.
The current may be alternating in character or polarity or may be continuous or
of one polarity and vary only in tension or amount and the pulsations may be
more or less abrupt in their changes, or, considered graphically as a series of waves,
the current may be either a sinusoidal current curve such as would be developed
by an ordinary dynamo generator of alternating currents or may depart in greater
or less degree from such curve as would be the case where the strength of current
rises with a greater degree of abruptness from zero or its least strength to its
maximum or greatest strength. Any character of rapidly varying and periodical
currents of a pulsating, intermittent, undulating, vibrating, alternating or other
character may be used. It is best to use a sinusoidal current, preferably an
alternating one.
or at
Another feature of the invention consists in using a rapidly varying current
rising and falling in strength from zero and generated by any desired means as
by an alternating current dynamo jand suppressing sinuses of said
current of any desired number
desired time by
of a prepared transmitting tape run synchronously with the dynamo and spaced or
organized to break and make the circuit at or about the times of zero propagation
or flow of current waves or pulses.
any
means
The recorder for the successive pulses or waves of alternating current may be of
any kind. For very high speeds it is preferable to use a photographic or a chemical
recorder. A form of photographic recorder suitable for the purpose, employing a
polarized beam of light rotated by the alternating or other pulsating current away
from the position of darkness produced by an analyzer will be hereinafter described.
Each pulse by rotating the beam causes it to become visible so that it will act on
the sensitive tape or sheet.
In the accompanying drawings
Fig. 1, illustrates partially in diagram the principle of the invention.
Fig. 2, is a diagram of a part of Fig. 1.
Fig. 3, is a graphic representation of the effect of the transmitter upon an
alternating current.
Fig. 4, represents in one form the record produced by the current indicated in
Fig. 3.
Fig. 5, is a diagrammatic representation of a commercial form of the improved
system.
Fig. 6, represents the transmission tape.
Fig. 7, represents the record produced by said tape.
Fig. 8, graphically represents the utilization of a direct undulatory current for
this system of transmission.
In describing the invention reference is had to the alternating current, though
it must be expressly understood that the invention is not hereby limited to the
employment of the alternating current, since, as will be hereinafter shown, it
may be operated by or over any varying current having clearly defined periodic
variations, preferably a uniformly varying one. It is preferable, however, to use
an alternating current dynamo and control the pulses thereof as herein described.
The term semi-cycle will be used herein in its ordinary sense to mean the portion
of a current wave extending from at or about one zero point to at or about the next
succeeding zero point.
The receiver or recorder of the pulsations may be as follows:-
S, represents a screen through which a ray of light, from any suitable source,
is admitted to the polarizing prism P, whence it passes through the medium T,

page_text: which under the influence of current flowing in the coil W, rotates the plane of
polarization of the ray of light. In the path of the beam as it emerges from this
medium is placed the analyzing prism A, which, in setting up the instrument to
work in the "crossed" or normally dark position, is rotated on its horizontal axis
until the light is completely extinguished during the cessation of current in
coil W. Then while current flows through the coil, the medium T, by rotating the
plane of polarization of the beam of light, causes said beam to emerge from A',
pass through the lens L, and fall upon the sensitized plate D, which may revolve as
here shown or move in any other manner.
-
A receiver of this sort responds instantaneously to changes in the current of
coil W. In fact, so sensitive is it that it clearly indicates the frequency of the
alternating current, the light affecting the sensitized plate during each semi-cycle
and being cut off during the interval between semi-cycles. For illustration see
Fig. 3, wherein O, represents the zero line with the + semi-cycles above and the
semi-cycles below. Starting from the zero line with no current flowing and no light
passing through A, the current wave as it forms a + semi-cycle causes light to pass
through A, then as the wave reaches the zero line the light is cut off to appear
again as the semi-cycle is formed and so on. The effect upon the sensitized plate or
film will be as indicated at 11, in Fig. 4, a succession of spots, or images of the
slit, corresponding to the successive semi-cycles.
To explain the way in which the alternating currents may be generated and
definite pulses thereof suppressed, reference will be made to Figs. 1 and 2.
Since in the alternating current circuit there is a cessation of current between
semi-cycles, or an instant when the current is naturally zero, it follows that to cut
out or suppress one or more complete semi-cycles will not affect the preceding or
succeeding ones nor in any way hinder the progress of the current over the circuit.
If the circuit is interrupted at the instant when the current is naturally zero, the
current will remain zero as long as the circuit remains broken, and with means for
controlling the duration of breaking the circuit, a single half period or semi-cycle,
or any number of half periods may be omitted at will and without producing any
sparking or burning whatsoever. One of the reasons for interrupting the circuit
when the current is naturally zero is the very practical one involving the question
of sparking at the brushes. If the current is zero when the circuit is broken, then
no spark appears at the break.
G, Fig. 1, represents an ordinary 10 pole alternating current generator from the
shaft of which through gears 12 and 13, is driven a wheel 14. This wheel is insulated
in any suitable manner and its circumference is accurately divided into forty (40)
parts, and, as the wheel is geared to run at one-fourth the speed of the armature,
each division thereof corresponds to one semi-cycle of the current produced.
Upon this wheel bear two brushes 15 and 16, carried by a rotating brush holder
for the adjustment of them about the wheel. These brushes and wheel are in the
circuit E, from the generator to the coil W, and one brush as 16, is preferably in
continuous engagement with the wheel.
Were the machine to be run as thus described, for each rotation of the wheel 14,
there would appear forty (40) light-affected spots upon the plate D, arranged as
indicated at 11, Fig. 4. But if one or more sections of the wheel 14, be covered
by paper or other insulation (indicated at 17) and the brush 15, adjusted to ride
onto and off of each insulation just as the current is changing from one semi-
cycle to the next, the semi-cycles represented by the section covered will be
suppressed and without any sparking no matter what the tension of the current.
For the sake of convenience in illustration, the Continental code of telegraphy is
followed and one semi-cycle is suppressed for a dot and two successive one for a
dash. Dots and dashes are separated by one semi-cycle, letters by two, words by
three and sentences by four or more. This is seen in Fig. 3, where (as indicated by
dotted lines) for the dot of w, one-semi-cycle is suppressed, then one
is retained, then for the first dash one--and the succeeding
pressed, then one - semi-cycle retained, and for the last dash one + and the succeed-

page_text: ing semi-cycles are suppressed. Then between the wand o two semi-cycles are
retained and so on through the word "work.". This is carried out on the wheel, as
indicated, by beginning at x, and covering one space, leaving one, covering two,
leaving one, covering two, and then leaving two for the space between w and o,
and so on for the word "work" between the end of which and x, six sections are
left bare.
The wheel having been thus prepared and the brushes adjusted, the brush 15,
may be raised from the wheel, the generator started and the plate D, set into
rotation. Then by lowering the brush 15, upon the wheel in the bare space 18, the
waves of the current will be recorded in regular succession as at 11, until the first
covered section is reached when one semi-cycle will be suppressed for the dot of w,
then one semi-cycle recorded, then two semi-cycles suppressed by the second piece
of insulation, for the first dash of w, then one semi-cycle recorded, then two
suppressed by the third piece of insulation for the second dash of w, then two
successive semi-cycles recorded for the space between w and o, and so on through
the word which, as illustrated, is followed by the record of six successive semi-
cycles, (see Fig. 4).
Having now shown how the suppression of the semi-cycles of an alternating
current may be accomplished at will and intelligence legibly transmitted thereby,
it only remains to disclose how this system may be made commercially practical.
Fig. 6 shows the message to be sent produced upon a tape of suitable insulating
material, preferably by punching in any perforating machine capable of producing.
the perforations at regular intervals and of making the spaces between them exact
multiples of the perforations and intervals. Where two or more space perforations
come together, as between letters and words, the divisions of insulation between
them may be omitted since said divisions come at the zero point between successive..
semi-cycles and the same effect will be produced upon the photograph in either -
instance.
"
In Fig. 6, a tape is illustrated as perforated for the message one wire
work of ten." This tape may be fed between contact surfaces which meet
through the perforations and are separated by the portions of tape between
perforations, the material of the tape being used to suppress sinuses in the same
way as did the patches upon the wheel 14, and the perforations providing for the
propagation of those sinuses or semi-cycles which are to cause the light to pass
to the sensitive plate or film. In the message tape then, as an illustration, the
first letter o, whose equivalent is three dashes, is represented by a series of three
blank portions of tape separated by single perforations. Therefore, each such blank
portion will cause the suppression of two successive sinuses or semi-cycles. A
blank portion equal to one perforation will cause one sinus to be suppressed, and,
as stated above, the suppression of one sinus means a dot upon the photograph
and the suppression of two in succession means a dash. Then the dots, dashes..
letters, etc., being separated in the tape by perforations they will be separated upon
the photograph by light affected spots, or what are in effect photographs of the.
transmitted sinuses.
In Fig. 7, is represented the record of that portion of the alternating current
upon which the above message has been imposed. It will be noticed that the black
spots in Fig. 7, correspond exactly to the perforations in the transmitting tape
and that they, like the perforations, represent the intervals between characters,
letters, words and sentences.
The prepared tape should be fed at a speed exactly corresponding to the succession
of semi-cycles of the current of the line, so that the parting and meeting of the
contacts may occur uniformly and at the zero points of the wave.
The synchronous speed may be obtained from the alternating generator or from a
motor run in unison therewith.
In Fig. 5, the message tape 19, is fed from a reel 20, between a pair of tension
rolls 21, and around a pulley 22, geared to the armature shaft of the generator. A
nipping roll 23, may be used to keep the tape to the pulley 22, and direct its

page_text: delivery. Wheel 22, may if desired be supplied with pins to enter a series of
feeding perforations in the tape the same as in the Wheatstone transmitter.
The contacts co-operating with the tape may consist of a wheel and brush, as in
Fig. 1, or of two brushes as 24, which are placed at an angle to the tape and meet
through the perforations therein. These brushes may be made adjustable in a
standard 25, and the standard made adjustable upon its base as indicated. This
adjustment of the brushes longitudinally of the tape provides for placing them in
such a position in relation to the perforations that they shall meet and separate
on the edges of the perforations at the zero points in the current and so produce a
clear record and prevent sparking.
As shown in Fig. 1, the receiver may be operated directly in the line circuit E,
from the generator by a coil W, or as in Fig. 5, the receiver may be operated in a
circuit E, derived from the line circuit E, through any suitable transformer as
indicated at I. In this way any number of receivers may be operated from the
same main line, a second branch thereof being indicated in dotted lines at E.
With this system, from a trans-continental line, the same message can readily be
-delivered at receivers all along the route.
Further, in the operation of the system, the interrupter has been placed in the
secondary circuit with the receiver as by putting a transformer across the mains
(Fig. 1,) just outside the binding posts of the generator G.
To obtain the message in legible form from the receiver, the photographic
tape D', upon which it is received may be run through a bath of "developer" as
at 27, and then through a bath of "fixer" as at 28, whence it may be delivered by
rolls 29. These rolls may, if desired, be heated so as to dry the tape as it is
delivered. This tape is shown as passing from a reel at 30, over a roll 31, and
vertically downward into the bath 27. All these parts may be placed in a dark
case as indicated and a slit provided for the admission of the beam of light from
the lens or the entire receiver may be in the dark room as desired.
In operating this system the perforated tape is fed to the transmitter which
suppresses semi-cycles of the line current in the required number and order in
accordance with the code used. The transmitted semi-cycles act in the receiver to
allow the beam of light to reach the rapidly moving sensitive tape in a manner to
reproduce the semi-cycles both as to duration and intervals. The sensitive tape
is fed through the developing and fixing baths and issues bearing a legible message
substantially as indicated in Fig. 7.
The form and construction of the transmitter are obviously capable of great
variation. Also the receiver may be of other kinds or forms capable of making a
record which will show which pulses have been suppressed and which transmitted.
Instead of alternating currents direct undulating currents such as graphically
represented in Fig. 8, by the wavy line 32, above the zero line may be used. The
transmitter may then be arranged substantially as above described to cut off a
portion of certain undulations in accordance with the code adopted, and the coil W,
included in the line circuit. Then by setting the analyzer so as to cut off the
light when a certain amount of current is flowing, say that represented by the lower
portions of the curves of line 32, the plane of polarization will be rotated by the
medium T, when that greater amount of current represented by the upper portions
of said curves, is flowing and the light will be allowed to pass to the sensitive
tape. With the conditions as just outlined an uninterrupted flow of current will
produce upon the moving photographic tape a succession of light-affected spots, the
same as with alternating currents.
Then by cutting off the tops of certain waves, substantially in the manner hereto-
fore described, and in accordance with the Continental code, as indicated by the short
lines 33, Fig. 8, a message can be sent which will appear upon the tape in the same
manner as indicated in Fig. 7.
The transmission of intelligence, however, by a direct undulating current
operated upon in the special way indicated in Fig. 8, cannot be effected as rapidly
as by an alternating current because only a part of the current can be utilized,

page_text: to wit: the upper portions of the waves, and because of the impedance on the
line and the extra currents occasioned by the breaking and making of the current
for the production of each character, when the flow of the undulating or pulsating
current is interrupted above the zero line instead of at the times of zero propagation
or current.
Instead of suppressing or cutting out portions of the current to represent the
characters and allowing the transmission of current to produce the spaces, portions
of the current may be suppressed to represent spaces and the portions of current
transmitted be made to produce the characters. It is plain that any dot or dash
code can be readily imposed upon the current.
The special receiver described responds instantaneously to the transmitted periods
of current by passing the light to the sensitive tape and to the periods suppressed
by obstructing the passage of light to said tape. So far as known, this receiver is
the most sensitive, rapid and accurate one that can be devised but obviously other
forms of receiver may be operated by the mode of transmission described, for
example, those affected by changes in polarity and those popularly known as
electro-chemical receivers in which a chemically treated strip of paper is discolored
by the passage of the current. The high potentials which it is possible to employ
with this system of transmission make it practicable to employ many other forms of
receiver even with a very high speed of transmission.
By this system of telegraphy many thousands of words per minute may be
transmitted and received.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:-
1. In an automatic system of telegraphy, an alternating current generator com-
bined with a prepared message such as a perforated tape run by suitable mechanism
synchronously with said generator and spaced or organized to produce breaks and
makes of the circuit at or near the zero points of the alternating current and to cut
out as described predetermined semi-cycles of said current.
2. The improvement in the art of transmitting intelligence which consists in
imposing the characters of a code upon a rapidly varying electric current, prefer-
ably an alternating current, by interrupting the flow of determinate pulses thereof
in definite order or succession by means of a synchronously operating transmitter
having a prepared tape, and receiving the message in a receiving instrument adapted
to make a visual record of the pulses and show the order or relation of the pulses
transmitted and interrupted.
3. The combination with an alternating current generator and the electric circuit
traversed by alternating electric currents flowing from said generator, of a circuit
breaking tape in the working circuit over which said alternating currents flow,
spaced or adjusted to open the circuit at the instant the working current flowing
over said circuit is zero.
4. The combination of a generator of alternating or other periodically varying
electric currents and a perforated tape movable at a speed corresponding to that of
the generator for controlling the flow of said currents, said perforations being so
arranged that complete determinate semi-cycles will be transmitted or suppressed.
5. A telegraphic apparatus comprising in combination an alternating current
generator, a transmitter for suppressing determinate semi-cycles of the current,
and a receiver comprising means for producing a beam of polarized light and
rotating said beam by the action of the electric current, and a photographic
recorder.
6. The combination with means for producing an alternating electric current
and means for suppressing a definite semi-cycle or semi-cycles thereof, of a recorder
of the alternations comprising means for producing a beam of polarized light and
for rotating said beam by the action of the alternating current, and means for

page_text: photographing in a line the succession of spots of light corresponding to the
successive semi-cycles of said current.
7. The combination with an alternating current generator, of a perforated tape
movable at a speed corresponding to that of the generator for controlling the flow
of said alternating currents, said perforations being so arranged .that complete
determinate semi-cycles will be transmitted or suppressed, substantially as and for
the purpose described.
8. The combination with an alternating current generator, of a perforated tape
movable at a speed corresponding to that of the generator, and electrical contacts
adapted to meet through the perforations of the tape, said perforations being so
arranged that complete determinate semi-cycles will be transmitted.
9. The improvement in high-speed telegraphy, substantially as hereinbefore
described.
D
T
101 1
1
1007
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.