IMPROVEMENTS IN CIRCUITS AND INSTRUMENTS FOR CHEMICAL TELEGRAPHS
Year: 1873

page_text: LETTERS PATENT to Thomas Alva Edison, of Newark, in the State
of New Jersey, United States of America, for the Invention of
** IMPROVEMENTS IN CIRCUITS AND INSTRUMENTS FOR CHEMICAL TELEGRAPHS.”
PROVISIONAL SPECIFICATION left by the said Thomas Alva Edison
at the Office of the Commissionors of Patents, with his Petition, on
the 27th February 1878.
I, THOMAS ALVA EDISON, of Newark, in the State of New Jersoy,
United States of America, do hereby declare the nature of tho said
Invention for "IMPROVEMENTS IN CIRCUITS AND INSTRUMENTS FOR CHEMICAL
TELEGRAPHS," to be as follows:-
On long telegraph lines the pulsations that produce the dots and dashes'
upon the chemical paper become so much attenuated as to be indistinct'
or to run into each other. The rapidity of the transmission is therefore
lessoned with the increase in the length of the line.
My improvements are to obtain greater rapidity in transmission.
in consequence of cutting off the tailings of the dots and dashes by
neutralizing the attenuation of the pulsations.

page_text: I have discovered that the counter current set up in an electro-magnet
or induction coil, when the circuit is broken, will neutralize the attenua-
tion of the pulsation. I therefore introduce such magnet in a shunt or
branch circuit, so that in the discharge of the magnetism the reverse
current shall operate to clear the line of the tailings.
The electro-magnet or induction coil is sometimes introduced in a
branch circuit from the line to the earth. At other times it is in a shunt
contiguous to the receiving instrument.
Two or more stylus or pens, with shunt circuits and differing magnets
to cach, ensure legible charactors in one of the soveral lines of 1
characters.
At local stations drop copics can be taken by dividing the circuit,
placing the magnet in the branch, or the same thing can be done in a
branch circuit running to the earth, or the magnet may operato a
sounder or call. A glass of water, with the ends of the line wire and 1
the ends of local circuit wires to the receiving instrument, may bo
employed for drop copies. When a resistanco is placed in the main line,
and a circuit breaker is in the line operated with great rapidity so as to
keep the line charged statically, the message will be sent by the perforated
paper and stylus acting in a shunt that is connected with the line at :
both sides of the resistance.
The secondary current set up in an induction coil is employed for
repeating a message. The primary circuit from the transmitting instru-
ment acts in one coil, and that induces a secondary circuit in another
coil connected with a receiving instrument. This device becomes an
induction relay that acts with as great rapidity as the automatic trans-
mitting instrument.
The secondary circuit may act in a second induction relay, or it may
be used for drop copies, or for branch circuits running off from the main.
line. In order to clear the line from surplus elcotricity batteries are
connected with the line at suitable distances apart, with their poles.
opposed to the main battery, but of much less power, and these batteries
serve to neutralize or aid in neutralizing the tailings, and render the
mark upon the chemical paper clear and distinct. These reaction
batteries are either in the main line or in branch or shunt circuits. .

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Thomas Alva Edison in the Great Seal Patent
Office on the 27th August 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS,
ALVA EDISON, of Newark, in the State of New Jersey, United States of
America, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-seventh day of February, in the year of
our Lord One thousand eight hundred and seventy-three, in the thirty-
sixth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Thomas Alva Edison, Her special licenco
that I, the said Thomas Alva Edison, my executors, administrators, and
assigns, or such others as I, the said Thomas Alva Edison my executors,
administrators, and assigns, should at any time agree with, and no others,
from time to time and at all times thereafter during the term therein
expressed, should and lawfully might make, use, exercise, and vend,
within the United Kingdom of Great Britain and Ireland, tho Channel
Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN CIRCUITS
· AND INSTRUMENTS FOR CHEMICAL TELEGRAPHS," upon the condition (amongst
others) that I, the said Thomas Alva Edison, my executors or adminis-
trators, by an instrument in writing under my, or their, or one of their
hands and scals, should particularly describe and ascertain the nature of
the said Invention, and in what manner the same was to be performed,
and cause the same to be filed in the Great Seal Patent Office within
3 six calendar months next and immediately after the date of tho said
Letters Patent.
"
NOW KNOW YE, that I, the said Thomas Alva Edison, do hereby
declare the nature of my said Invention, and in what manner the samo is
to be performed, to be particularly described and ascertained in and by
the following statement, reference being made to the Drawings hereunto
annexed, and to the letters and figures marked thereon (that is to
say) :—
Before this Invention telegraphic circuits had been arranged with a
'rheostat to regulate the portion of the electric pulsation passing to tho
5 chemical paper, and allowing the other portions of the pulsation to pass
along the main line or to go to the earth as a leakage. In these cases.

page_text: the rheostat did not produce any counter current, and served only to
direct portions of the clectrical waves through the chemical paper, but
the tailing and attenuation of the mark was not avoided, and upon
long lines these marks usually ran together, because there was not suffi-
cient time for the electric action to cease, or the line to free itself before 5
another pulsation succeeded, and the line became surcharged.
In all cases it has been desired to obtain the most perfect insulation
of the line to avoid the use of powerful batteries, and to lessen atmos-
pheric influences. It has however been found that when the insulation
is impaired by atmospheric influences the marks' upon the chemical 1
paper are more distinct, because the surplus electricity finds vent in
currents to the earth, lessening the tailing.
When an electro-magnet is charged by a pulsation the electric action.
in the circuit of which the helix of the magnet forms a part is aug.
mented, but when the main or line current is broken the magnet in 1
discharging itself of the magnetism that has been induced sets up
momentarily a counter current or one of opposite polarity.
I avail myself of these various conditions, and arrange the circuits in
such a manner that the electro-magnets which are energized by the
pulsation that makes the mark on the chemical paper serve to intensify 2
the electric action upon that paper, but that the counter current, set
up when the primary circuit is broken, shall neutralize the tailing or
attenuation of the current by the discharge of the magnetism from the
electro-magnet, thereby allowing for the use of very feeble currents, and
rendering the marks upon the chemical paper sharp and clear, and I 2
furthermore employ upon long lines one or more earth connections, in
which are placed one or more electro-magnets, with or without rheostats
to regulate the proportion of currents passing to the earth, such connec-
tions and electro-magnets serving to free the line from surplus electricity
and by the reverse polar action, as the electro-magnet discharges itself, 3
to free the line from any attenuation of the primary pulsations.
With long lines it is preferable to employ long electro-magnets, and
the roverse, in order that the time occupied by the magnet in discharging
its magnetism may be proportioned to the attenuation or tailing of the
main current that is increased by the length of line.
31
In the Drawings Fig. 1 shows by a diagram the connections to effect
this object. a is the transmitting instrument of the well known character,.

page_text: in which a strip of perforated paper is drawn along between the drum
and stylus or roller to open and close the main line circuit, and produce
the pulsations of electricity that travel over the line in the direction of
the arrows 3, and make a mark at the distant recording instrument &
'upon a strip of chemical paper drawn along between the stylus and
roller. The current is divided, part passing by the wires 2, 2, in what is
called a shunt, and in this is placed the electro-magnet c, or an induction
'coil. As each pulsation ceases in the main line a reverse current is sot
up in the shunt in the direction of the arrows 4 by the discharge of the
magnetism of the core of the electro-magnet or induction coil. This
cuts off any tailings in the pulsation of the main line, and prevents
attenuation in the mark on the paper.
The electro-magnet or induction coil is sometimes introduced in a
branch circuit from the line to the earth, as at e. At other times it is
in a shunt contiguous to the receiving instrument.
Two or more styluses or pens with shunt circuits and differing magnets
to each ensure legible characters in one of the several lines of characters.
These are shown at f,f,f, Fig. 2, and it will be understood that the
electrical conditions differing in the circuits to the different styluses that
one of the lines of marks on the chemical paper is almost sure to be clear
and legible, because of the electrical condition being correct.
At local stations drop copies can be taken by dividing the circuit,
placing the magnet o in the branch, as at g, Fig. 1, or the same thing
can be done in a branch circuit running to the earth, as at e, or tho
magnet may operato a sounder or call or a local circuit, as at 1, Fig. 2,
where the magnet c is represented as a relay operating in the local circuit
from a battery & to the receiving instrument b. A glass of water, with
the ends of the line wire and the ends of local circuit wires to the
receiving instrument, may be employed for drop copies, as seen at 7,
Fig. 2.
When a resistanco or rheostat R, Fig. 2, is placed in the main line,
and a circuit breaker o is in the line operated with great rapidity by a
revolving magnetic motor p, or otherwise, so as to keep the line statically
charged, the message will be sent by the perforated paper, and the
stylus acting in a shunt that is connected with the line at both sides of
the resistance, the battery B charging the line directly through the

page_text: perforations of the paper, and producing pulsations of greater intensity
than the static charge.
The secondary current set up in an induction coil is employed for
repeating a message. The primary circuit from the transmitting instru-
ment acts in one coil, and that induces a secondary circuit in another
coil connected with a receiving instrument. This device becomes an
induction relay that acts with as great rapidity as the automatic trans-
mitting instrument.
In Figs. 3, 4, 5, 6, & 7 these induction relays are represented. The
transmitting instrument a, battery B, receiving instrument 6, and induc-]
tion coil or electro-magnet c, to react and neutralizo the tailings as the
main line circuit is broken, are the same as before described, but the
pulsations of electricity from the sending station only pass through an
induction relay coil t, and that, by the well known principles of induc-
tion, sets up a current in the surrounding helix, Fig. 3, or connected
helix n, Fig. 4, and this secondary or induced current either operates the
receiving instrument, as seen in Figs. 5 and 6, or else it operates in a
second induction coil 1, Fig. 3, and that becomes a relay and sets up
another current in the second induction coil n', and this operates in the
receiving instrument.
Fig. 7 illustrates connections that may be made under this mode of
operating:-New York is represented as the sending station. At New
Brunswick a drop copy is being taken by the secondary or induced
current from the induction relay. At Philadelphia the induction relay
coil n is connected to earth at v, and to the line wire extending to Pitts-
burgh, and there operates in the receiving instrument. At Harrisburgh
the line passes through an induction relay that sets up a current in the
line reaching to a receiving instrument at Buffalo. At Baltimore a
connection is shown from the relay coil n to Cincinnati, and the main
pulsations from New York extend through to the receiving instrument at
Washington.
In order to clear the line from surplus electricity reaction batteries aro
connected with the line at suitable distances apart, with their poles
opposed to the main battery, but of much less power, and these batteries
servo to neutralize or aid in neutralizing the tailings, and render the
mark upon the chemical paper clear and distinct. These reaction

page_text: batteries are either in the main line or in branch or shunt circuits. Theso
reaction batteries are marked to, and by reference to Figs. 6, 8, 0, 10, 11,
12, & 13, tho arrangements and operations will bo apparent.
In Fig. 8 there are several branch circuits ³, in which aro placed
› rheostats or resistances R that may be adjustable, and also batteries wo
that are of the proper power, and placed with the opposite pole to the
line to that of the battery B, so that the line is operated upon in detail
'at suitable distances apart, say every one hundred miles more or less,
and the line freed from tailing, and the same is opposed to the main
current but not sufficiently powerful to neutralize the same, or to inter-
fere with the transmission. These batteries to are so proportioned or
adjusted as to be equal to the static current or electricity gonerated by
the passage of the main current.
=>
In Fig. O the same parts are employed, but the opposition batteries w
› are placed in the main line and distributed along the same. The branch
circuits to the carth, with resistances R, act with the local opposition
batteries to establish currents counter to the main current…
In Fig. 10 the effect produced is the same as before described, but in
place of rheostats there are condensers P, and the opposition local
O batterics w acting upon the condensers establish an opposite polarity on
the plates of the condensers that are connected with the line to the polarity
of such plates when influenced by the transmitting battery, thereby
neutralizing the tailings by charging the line statically in opposition to
that from the main current.
The condensers may be connected with the opposition local batteries
in the manner seen in Fig. 11, so that the plates that are connected to
the line will be influenced by the other plates of the condenser that aro
connected with the earth and the other pole of the battery, the operation
being similar to that before set forth.
-
In Fig. 12 the parts are the same in their operation as those before
described, but instead of ordinary batteries cups #, containing platina or
carbon strips and acidulated water, are employed, so that when the pul.
sation on the main line ceases to chargo such cups a momentary reverse
current is established to neutralizo the tailings by instantly freeing the
5 line of any electric charge.

page_text: Fifth. One or more batteries in the main line, or connected therewith,
having their poles opposed to the main line current to noutralize tailings
in the pulsations.
In witness whereof, I, the said Thomas Alva Edison, have hereunto
set my hand and scal, this Twenty-fourth day of July, A.D. 1878.
Witnesses,
CHAR. H. SMITH,
121, Nassau St.
New York.
HAROLD SERRELL,
121, Nassau St.,
Now York.
THOMAS ALVA EDISON. (L.s.)