IMPROVEMENTS IN AUTOMATIC CHEMICAL TELEGRAPHS COMPRISING TRANS- MITTING AND RECEIVING INSTRUMENTS, CIRCUITS, AND APPARATUS CONNECTED THEREWITH, PART OF THE SAID IMPROVEMENTS BEING ALSO APPLICABLE TO OTHER TELEGRAPHS
Year: 1874

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane,
in the County of Middlesex, Patent Agent, for the Invention of
"IMPROVEMENTS IN AUTOMATIC CHEMICAL TELEGRAPHS COMPRISING TRANS-
MITTING AND RECEIVING INSTRUMENTS, CIRCUITS, AND APPARATUS CONNECTED
THEREWITH, PART OF THE SAID IMPROVEMENTS BEING ALSO APPLICABLE TO
OTHER TELEGRAPHS."-A communication from abroad by William
Edward Sawyer, of Washington, District of Columbia, United
States of America.
PROVISIONAL SPECIFICATION left by the said Alexander Melvillo
Clark at the Office of the Commissioners of Patents, with his
Petition, on the 26th November 1874.
I, ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County
of Middlesex, Patent Agent, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN AUTOMATIC CHEMICAL TELEGRAPHS, COMPRISING
TRANSMITTING AND RECEIVING INSTRUMENTS, CIRCUITS, AND APPARATUS CONNECTED

page_text: THEREWITH, PART OF THE SAID IMPROVEMENTS BEING ALSO APPLICABLE TO OTHER
Telegraphs,” to be as follows :—
This Invention relates to a new and improved system of automatic
chemical telegraphs, comprising transmitting and receiving instruments,
circuits, and apparatus connected therewith, as hereafter described.
Many of the features of the present Invention are comprised in a
previous application for Letters Patent, filed by me on the 14th day of
November 1874, No. 3935, for a facsimile telegraph styled the new
pantelegraph, the use of which in an automatic chemical telegraph
was alluded to in the Specification of said application. It is designed
to apply any of the principles of either Invention to the operation of
the other.
According to the present Invention I make use of the commutating
principle of the new pantelegraph in the transmitting apparatus,
whereby I am enabled to make perfect electrical contacts by means of
metallic points or rollers falling through perforations in a sheet or
strip of paper at a speed of transmission which would greatly imperil,
if not absolutely prevent, perfect contacts in present automatic systems,
and whereby I am also enabled to charge a line of wire without sur-
charging it, thus enabling a line to sooner free itself, and in great
measure preventing or avoiding tailings. This will be obvious upon
reference to the commutator shown in the accompanying Drawings.
The form of the commutator may be varied in many ways, but its
principle is esentially the same as that shown and described in the
Drawings and Specification above alluded to.
To carry the commutating principle into effect I employ a strip, shect,
or roll of paper perforated crosswise so as to read as an ordinary printed
page, through the perforations of which drop a row comprising any
number of metallic points or rollers insulated from each other, which
metallic points or rollers consecutively, by means of the commutating
hand or disc and contact rollers are brought into the circuit of line
wire, battery, and earth, thus accomplishing an indefinite speed of
transmission of impulses by means of the perforated paper with an
indefinite slowness of motion of the perforated paper. message
received upon a fillet of chemically prepared paper as in the ordinary
automatic telegraph.
The
is

page_text: For producing the chemical discoloration necessary to record a
message I use the current from the main battery, but for clearing the
line of tailings or positive inductive effects I employ the brief intensity
impulse resulting from induction, which I produce by a local circuit
and battery operated by the row of contact points upon the perforated
paper and the commutator wheel and rollers.
I have shown in the Drawings double insulated pieces of metal upon
the commutator wheel, so arranged that in revolving under the rollers
the double pieces are electrically united, but I do not confine myself
to such an arrangement. In many cases double rollers as well as double
pieces upon the commutator wheel may be preferable; nor do I confine
myself to the arrangement of the rollers with relation to the picces upon
the commutator wheel; the positions may be reversed so that the
contact points upon the perforated paper shall be connected with pieces
upon the commutator wheel instead of as shown with the rollers. More
pieces than two upon the commutator wheel and a greater number of
contact rollers than is shown may be employed for purposes connected
with inductive effects, and putting the line to earth otherwise than
through the battery. I do not in fact limit myself to any of the special
forms and contrivances shown and described; the contact rollers of
the commutator wheel for instance may be as large in diameter as
the commutator wheel itself, and other like deviations from the plan
may be made use of.
I am aware that magnetic induction produced in a shunt or derived
circuit has been employed for the purpose of clearing a line of tailings;
but I am not aware that an ordinary induction coil, consisting of a
coarse primary wire and a relatively fine secondary wire surrounding
a bundle of fine iron wires, has been used for that purpose. I find that
a similar but greater clearing effect than can be produced by the
apparatus employed by Mr. T. A. Edison, is produced by an ordinary
coil placed either in a shunt or a branch circuit, the primary and
secondary wires of which coil are inserted in the circuit. Taking either
terminal as the starting point the line is joined to the beginning of the
primary wire, the end of which is joined to the beginning of the
secondary wire, and the end of the secondary wire in turn continues
the line. This spiral form of coil and connections produces a strong
depolarizing effect upon the line wire upon the cessation or marked
-
2

page_text: decrement of the current from the battery, and is of greatest value in a
shunt or branch circuit.
I also employ a double wire induction coil similar to the foregoing
at any point in the line, or in a shunt or branch circuit, and I cause it
to produce depolarizing effects independently of the cessation or decrement à
of the impulses proceeding from the battery.
The primary and secondary wires may be of the same or differing
lengths, resistance, or degrees of fineness, and I cause the coil and its
core to act by placing the wires alternately in the circuit, one wire being
cut out while the other is in the circuit by means of a rapidly revolving ]
current diverter or circuit changer, which may be made to divide a dot
or a dash impulse into very many dot impulses so far as each of the
wires of the coil is concerned.
In the Drawing and Specification of the former application above
referred to I have shewn a method of causing the coil to act by diverting 1
the current to earth outside the receiving instrument.
In arranging the induction apparatus to meet the requirements of a
line which is subject to constant changes in electrical condition, it is
desirable to be able to increase or diminish with facility both the resist-
ances of the coil and the inductive effects from the magnetized iron a
.cores, which may be in the form of bar iron or wire, straight or coiled
wire, or wire in layers, pieces, or single lengths. Hence I employ a case
of coils or spools of various lengths with suitable switches, and iron cores
of various lengths and diameters, which are withdrawn from or intro-
duced into the coils in the same manner as the connecting plugs of a
Bradley's resistance box accompanying the well-known Bradley tangent
galvanometer. I have found that a current will produce very little
"tailings" upon the receiving paper if a short and perfect ground be
made at the transmitting end of a wire outside of the battery at the
instant or nearly the instant of cessation of an impulse. When a shunt
circuit is employed the greater portion of the current from the battery
traverses the shunt, or is, so to speak, short circuited, and when the
battery is removed the portion of current which would have remained in
the short circuit, had the battery remained upon the line and shunt, is
distributed or attenuated, thereby in a measure charging the line before
the line can discharge or while it is discharging. A heavy battery is
also required to work over the shunt. To obviate these difficulties I usc

page_text: a special contact point or roller working upon the perforated paper,
whose duty is to form a ground for the line independent of the battery
just before, just after, or the instant the impulse from the battery ceases.
To accomplish this I employ a special row of perforations. The employ-
ment of condensers I have also found advantageous.
Having thus generally described the Invention, in order to enable
those skilled in the art to make and use the improvements I will describe
the same more in detail, reference being had to the accompanying
Drawings, in which
Figure 1 is a side view of the transmitting and receiving apparatus;
Figure 2, a top view.
Figure 3 is a sectional view of the commutator; and Figure 4, a
separate view of the receiving apparatus.
Figure 5 is a view of the double circuit charger for working the
induction coils.
In Figure 6 are shown one of the forms of perforation, being that
belonging to the special apparatus, Figures 1 and 2, and the style of the
received message.
Figure 7 is a diagram of the method of operating the induction coil
with a secondary battery.
Figure 8 is a diagram of a single circuit through the double wires of
an induction coil.
Figure 10 is a view of the method of perforating paper in application
to the ordinary automatic instrument for forming a special ground, et
cetera.
Figures 9, 11, 12, 13, and 14 are diagrams of circuits.
Figure 15 is a view of a non-inductive wire resistance.
Like letters of reference indicate similar parts in all the Figures.
A is any suitable metallic frame for holding and supporting the various
parts of the apparatus; W is the driving wheel fixed to shaft o', with
large gear wheel G and pulley P³, which actuates pulley P fixed to
shaft o² with friction roller F for drawing the perforated paper i from
the reel a on shaft of over metallic drum D on shaft o³; n, n, are the
row of points on shaft o', which fall through the perforations in the
paper. These points are separate working, insulated from each other,

page_text: and electrically connected in the order in which they stand with the
tho
levers and rollers f, which are also insulated from each other, upon
demicircular frame m. The small gear wheel G', commutator disc C,
and pulley Ps are fixed to shaft o. Pulley P' actuates pulley P¹, which
is fixed to shaft with friction roller F', which draws the chemically
prepared paper from the reel a' over the metallic receiving drum D¹,
and beneath the recording stylus d of lever b in standard S. The com-
mutator wheel or disc C is made of some insulating substance, or so that
the metallic pieces e and e' upon its periphery are insulated from the
rest of the wheel. There are five pieces e and five pieces e¹. The five
pieces e are electrically connected together and with the metallic band j',
which is insulated from the shaft o. The five pieces e' are in like manner
connected with the metallic band j¹ upon and insulated from the shaft o.
The springs K and K', bearing upon the bands j and j³, are insulated
from the frame, and convey the currents proceeding from the com-
mutator wheel C to the wires. As the roller of lever f comes between
the pieces e and e¹ the pieces e and e' arc clectrically connected, which
connection is broken when the pieces e and e¹ arc carried away from the
roller. The object of having a numbe of pairs of pieces e and e¹ on the
commutator wheel C is to enable the apparatus to pick up the impulsos
which may proceed from the points n fallen through the perforations in
the paper i very rapidly without making a revolution of the wheel C
every time the impulses are gathered up. For instance, onc pair of
pieces e and e' will have passed and made contact with all the rollers f
before another pair of pieces e and e¹ begins to make such contacts. It
is obvious that the number of these pairs of pieces may be increased
indefinitely.
Although I have shown the commutator parts sectionally in Figure 3,
and the receiving parts separately in Figure 4, I have only done so to
show clearly the nature of the apparatus,
The connections between the points n and rollers will be understood
from the ends of the wires cut off proceeding from each. The method
of perforating the paper for this form of transmitter is obvious from
Figure 6, in which J is a piece of a roll or strip of paper with the
perforations in dots and dashes. The message reads across the roll or
strip of paper as any ordinary printing page. The lines of perforations
are but slightly separated, and at such an angle as would cause the end
of one line to connect upon the same inclination with the beginning of

page_text: the succeeding line, supposing the left and right-hand sides of the roll
to be brought together; in other words, the lines from what might be
termed a plane spiral. The message is not however recorded in the same
form, but in the usual way upon a continuous fillet of chemically pre-
pared paper, as shown by L.
.
The double circuit changer, Figure 5, is an important adjunct to this
system. N and N' are two metallic bands, discs, or wheels, insulated
from each other, but revolving with the same shaft, which is caused to
turn with great rapidity by any suitable mechanism. The pieces z are
also of metal, inlaid, but insulated from the body of the discs. They
are of equal number upon each disc, and the spaces between them are
of the same width as the pieces themselves. It will be seen that the
pieces are not opposite each other, but are so arranged that the pieces
on one disc are opposite the spaces on the other disc. The metallic
contact rollers Q and Q' however are on a line one with the other, so
that when the roller Q is on a space the roller Q' is on an insulated piece,
and vice versa. The pieces extend all around the discs, and may be of
any number and size. The contact rollers are held against them by
spring shafts or any suitable device. U, U¹, V, V¹, aro standards all
insulated from cach other, but cach connected with its contact roller
disc; I² is a double wire induction coil, the dotted lines representing the
primary wire. The coil is placed at any desired point in the line, branch,
or shunt circuit.
The manner in which the coil operates is obvious from the arrange-
ment of the wires. When the roller Q is in contact with the metal of
the disc N the current flows, say, from the line wire L, W, to the left
through standard U to disc N, roller Q to standard V, and through one
of the wires of the coil I to the line at the right. When the roller Q
touches a piece this circuit is broken, and a depolarizing impulse is
thrown into the line through the other wire, which is now in circuit, say,
from the left through the other wire of the coil to standard V₁, roller Q³,
disc N', standard X', U', and line to the right. By this arrangement
the line is never broken, but its electrical condition is maintained in
constant equilibrium, and at the cessation of an impulse from the secon-
dary battery the attenuation or tailing of the current is instantly
neutralized, and the writing comes sharp and distinct.
In Figure 7 is shown the main circuit from the transmitting instru-
ment and the local circuit and battery for operating the induction coil_ I',

page_text: secondary battery B¹ is flowing through drum, perforations c¹, contact
point r, and primary wire of induction coil I', as shown by the dotted
line. The secondary wire of induction coil I' is in the wire from
earth E¹ to contact point p, which when points and leave per-
forations c¹ drops into perforation c, and not only gives the line a short
ground in which to discharge but allows the secondary wire of the
coil I to depolarize the line, thus clearing it of tailings. The per-
forations c for the discharging earth connection may fill up the entire
space between the perforations c¹ so as to give the line a continuous
ground alternately through induction coil to carth and through battery.
to carth.
The method of putting a double wire induction coil in a shunt-in-
shunt circuit at the receiving end is shown in Figure 11, where x is the
primary and y the secondary wire of the coil; R, R¹, and R² are
adjustable resistances. The induction in the secondary wire will flow
through resistances R³ and R to recording style of drum D', and the
induction from the primary wire will flow from coil direct to recording
style to drum and back to coil through resistance R*.
In Figures 12 and 13 are shown receiving and transmitting circuits,
in which I employ condenser Y in connection with adjustable resistances
for the purpose of accumulating tailings. The uses of a double wire
induction coil in connection with an independent double circuit changer,
such as shown in Figure 5, or a single circuit changer are so multifarious
that I deem it useless to exhibit them in Drawings. I may mention
and claim putting the recording style and receiving drum alternately
to carth, grounding the line outside of the receiving instrument at rapid
intervals, putting on and taking out with great rapidity between the
receiving instrument and earth of a resistance which when in the line
will so weaken the battery current as to prevent discoloration of the
chemical paper, causing one of the wires of an induction coil to work on
a shunt, as shown in Figure 14, creating depolarizing inductions locally
at any point of the line and independent of the line, and throwing them
into the line by means of the circuit changer, by which means the line
may be kept in equilibrium without regard to the action of the trans-
mitting apparatus, and many others of similar character readily suggestive.
These may be applied in shunts and branch circuits. I prefer to employ
as resistances sulphuric acid diluted to r, and nitric acid, nitric acid
having the least resistance of any liquid, excepting quicksilver, and

page_text: sulphuric acid coming next in order, the former standing as to copper
as 1,032,020 are to 1, and the latter as 976 are to 1. The advantage of
using these liquids instead of distilled water is apparent when it is con-
sidered that the resistance of distilled water compared to copper is
as 6,754, 208 are to 1. For slight resistances a column or columns of
quicksilver may be employed, but I do not claim this as my Invention.
I also employ for slight or even resistances insulated lead wire in
layers R, Figure 15, instead of coils, so that inductive effects are
neutralized, lead being a cheap metal and casier to handle than quick-
silver.
.
In operating ocean cables it is of advantage to employ equating
batteries of both polarities introduced into the cable at the receiving end
by any suitable devices. When the recording style is making a con-
tinuous mark it is evident that the cable contains a surplus of the
discoloring current, and the receiving operator introduces a neutralizing
current to clear the line. When the recording styles marking imperfectly
it is evident that the depolarizing charge in the cable is too strong and
the operator introduces a current of the same polarity as the discoloring
current. By using a magnifying glass the increment and decrement of
the currents, as indicated by the marks upon the chemical paper growing
darker or lighter, may be more easily watched and the neutralizing
batteries introduced accordingly. As any one of many devices will
accomplish the same thing and the process is not capable of illustration
I have not attempted to indicate it by Drawings. By its use a very
high rate of speed for cables may be obtained. It will be understood
that the neutralizing batteries are kept upon the cable only long enough
to render the writing clear and that they may be of different strengths or
powers.
.
In Figure 14 I show the operation of the double circuit changer
(Figure 5) at the receiving end of a line. When the circuit is diverted
by roller Q and disc n¹ through primary wire of coil I³ to earth and the
circuit is destroyed a strong depolarizing effect is produced upon the
chemical paper by means of the secondary wire of the coil in the shunt
with resistances R.
I also employ the following method of producing clear and sharp
writing upon the recording, paper, using any of the well-known
devices of perforated paper and contact points for introducing the
currents :-

page_text: When required to transmit an impulse to be recorded I first transmit
an induced current of the same polarity as the impulse to be recorded,
then I transmit an impulse of opposite polarity to the impulse recorded
so as to sharpen and cut short the recorded impulse, following this by a
battery impulse-of opposite polarity to the impulse recorded, in the order
thus, Positivo induced current, positive battery current, negative
induced current, negative battery current, or I omit the negative battery
When required to transmit an impulse to be recorded I first transmit
an induced current of the same polarity as the impulse to be recorded,
then I transmit an impulse of opposite polarity to the impulse recorded
so as to sharpen and cut short the recorded impulse, following this by a
battery impulse of opposite polarity to the impulse recorded, in the order
thus, Positive induced current, positive battery current, negative
induced current, negative battery current, or I omit the negative battery
current.
I do not confine myself to the application of the improvements in line
clcaring adjuncts to the form of transmitting apparatus shown and
described, but reserve the right to apply them to any automatic apparatus
or to any other telegraphic system.
a
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Alexander Melville Clark in the Great Seal Patent
Office on the 26th May 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-sixth day of November, in the year of
our Lord One thousand eight hundred and seventy-four, in the thirty-
eighth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Alexander Melville Clark, Her special
licence, that I, the said Alexander Melville Clark, my executors,
administrators, and assigns, or such others as I, the said Alexander
Melville Clark, my exccutors, 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, the Channel Islands, and Isle of Man, an Invention
for "IMPROVEMENTS IN AUTOMATIC CHEMICAL TELEGRAPHS, COMPRISING Trans-
HITTING AND RECEIVING INSTRUMENTS, CIRCUITS, AND APPARATUS CONNECTED
THEREWITH, PART OF THE SAID IMPROVEMENTS BEING ALSO APPLICABLE TO OTHER
TELEGRAPHS," a communication to me from abroad by William Edward

page_text: the line by suitable apparatus only at the time or about the time that
the discoloring battery is removed from the line.
In arranging the induction apparatus to meet the requirements of a
line which is subject to constant changes in electrical condition it is
advantageous to be able to reduce or increase with facility both the
resistances of the coils and their inductive effects; hence I use a case of
coils or spools of various lengths, diameters and degrees of fineness, with
suitable switches and iron cores of various lengths and diameters which
may be withdrawn from or introduced into the coils or spools at will.
By this means any degree or quality of induced current may be
obtained.
I also employ double and single wire induction coils (the single wire
coil being practically the same as an ordinary electro-magnet, although
it may be made in many ways and acting inductively mainly by the
discharge of the magnetized core) which I place in branch or shunt
circuits generally in connection with the circuit changer, commutator,
or circuit diverter shown in the accompanying Drawings.
Having thus gencrally described the Invention, and in order to enable
those skilled in the art to make and use the improvements, I will describe
the same more in detail, reference being had to the accompanying
Drawings forming part of this Specification, in which
Figure 1 is a view of the transmitting drum, styluses, and perforated
paper. Figure 2 is a view of the circuit changer.
Figures 3, 4, 6, and 7 arc diagrams of circuits.
Figure 5 is a view of a non-inductive resistance.
The methods of construction of automatic transmitters are so well
known that in illustrating this Invention (Figure 1) I have deemed it
unnecessary to show more than the metallic drum and styluses with the
position of the perforated paper. The points of the styluses bear upon
the moving paper fillet, and as usual make contact with the metallic
drum as the perforations come under them. The paper may be moved
over the drum and under the styluses by any suitable mechanism.
The paper A is perforated in two rows although the perforations may
be so shaped that one row will suffice; the lower row b being that
through which the main battery is put to line by one of the styluses;

page_text: and also through which the local battery is sent through the primary
wire of the induction coil by another stylus, the upper row of perfora-
tions c being that by means of which the secondary wire of the induction
coil is placed in the line circuit. D is the metallic transmitting drum;
p, r, t, are the three styluses, which may be either metallic points,
brushes, or rollers; I is the induction coil; B the main battery; R,
rheostat; and E, main battery earth; E is the earth to the secondary
wire of induction coil I, although both carths may as well be the same;
B' is the local battery, flowing as per dotted line through the primary
wire of coil I.
The operation of transmission is as follows:-When one of the lower
row of perforations 6 comes under the styluses r, t, two circuits are set
up. In one the main battery B flows through stylus & and drum D to
linc. In the other the local battery B flows through drum D, stylus 7,
and the primary wire of the induction coil I, as shown by the dotted
line, this being a local circuit thus charging the coil. At the instant or
nearly the instant that the main battery B is removed from the line by
the perforation 6 passing from under the stylus t, stylus p drops into
perforation c, when the line is put to earth E¹, without battery, through
the secondary wire of coil I. Not until this contact of stylus p with
drum is made, however, does stylus leave perforation b, as it is
necessary to have the secondary wire of coil I in the line circuit before
discharging the coil. Now that the circuit through the secondary wire
is established the local battery circuit through the primary wire of the
coil is broken and a brief intensity current of opposite polarity to the
main battery current is thrown into the line by means of the secondary
wire of coil I, effectually clearing the line and rendering the writing at
the receiving end clear and sharp.
It should be understood that I do not confine myself to the applica-
tion of this inductive principle to automatic telegraphy in any form.
It will be obvious to any one examining the Specification before alluded
to in what manner it may be applied to that Invention; as shown in the
Drawings of said Specification the commutator wheel concentrates into
one line the many impulses proceeding from the many wires leading to
the message to be transmitted. A single wire induction coil may be
placed in a shunt, but the result would be a short circuiting, which would
be prejudicial to the contact points; hence I should place upon the
commutator wheel such an arrangement of contact pieces, that the

page_text: instant an impulse should be transmitted over the line an induction.
coil should throw into the line a depolarizing current for the purpose of
clearing it.
The double-circuit changer, Figure 2, is an important adjunct to this
system; I have shown it made in one way, but it may be made in many
ways so changed or varied that one shall bear little resemblance
mechanically to another, but the result will be practically the same in
every case. In the Drawing (Figure 2) C is a metallic drum, disc, or
wheel, upon the periphery of which arc let in certain insulating picces Z
through which no current can pass; H and H³ are metallic contact
rollers, each insulated from the other and both insulated from the drum,
disc, or wheel C on base G; S, S, are springs by which the rollers are
held against O; M and N are the insulating [pieces by which the springs
and rollers are insulated from base G. It will be observed that the
metallic contact rollers H and H₁ are so placed that while one is
making connection through disc C with standard F the other is
insulated from standard F. The pieces Z may be of any size and extend
all around the disc. The disc C is rapidly revolved by any suitablo
mechanism.
i
The uses of the circuit changer are so multifarious that I have
deemed it useless to exhibit all its uses in the Drawings accompanying
this Specification. I may mention for example, putting the recording
style and the receiving drum alternately to earth, grounding the line
outside the receiving instrument at rapid intervals, putting in and taking
out of the line or shunt or branch circuit of a resistance (Figure 7),
causing an induction coil to work in a shunt or branch (Figures 7
and 4); creating depolarizing inductions at any point of the line in
branch or shunt circuits (Figure 6), putting in and taking out
depolarizing batteries, and many other uses of similar character readily
suggestive.
In Figure 3 I have indicated a method of putting a double wire
induction coil in a double shunt circuit. At the receiving instru-
ment R,g, in which is the primary and y the secondary wire of the
coil, R, R', and R² are adjustable resistances. Upon the cessation of
the transmitting current from the other end of the line two induced
currents will be set up, the one from the secondary wire of the coil
flowing through resistances R and R³ to recording stylus of drum D¹,

page_text: and that from the primary wire flowing through resistance R³ to tho
recording stylus, thus depolarizing the stylus.
In Figure 4 I show one operation of the circuit changer at the
receiving end of a line. The drum C of circuit changer alternately
carries the line current to earth E¹ through the roller H¹ and primary 5
wire of the induction coil I, and to the recording stylus of drum D'
through roller H to earth E. When the circuit through roller H³,
primary wire of coil I, and earth E' is broken, a depolarizing influence
upon the recording stylus and chemical paper is produced by the dis-
charge through the secondary wire of the coil I, through recording 1
stylus drum C and resistance R, rendering the writing clear and sharp
cut.
In Figure 5 I show the manner of forming a non-inductive resistance
which I prefer to employ, consisting of insulated wire in parallel return-
ing layers, so that the induction by one layer is neutralized by that of 1
another. Layers in continuation of the same wire may be arranged
crosswise of those shown for the purpose of increasing the effect.
•
In Figure 6 I indicate a method of working with depolarizing induc-
tions in a shunt circuit at the receiving end of a line. If a depolarizing
battery be placed in the line or a shunt or branch circuit, and the lino 2
be operated by working over such depolarizing battery by the main
transmitting battery, which is much stronger than the depolarizing
battery, the depolarizing battery is thrown out of equilibrium and a
certain space of time is required in which to recover, hence great speed is
impossible with such a line clearing adjunct. An induced current, steady 2
or otherwise, in shunt, branch, or main circuit is subject to no such
difficulties. It has no chance to loose its equilibrium, and by its use the
line may be operated by the increment and decrement of the trans-
mitting battery current solely. The induced current, which may be
created magneto-clectrically or by coils, should be continuous of opposite 3
polarity to the transmitting current, and of a given strength, which the
transmitting current will neutralize and overcome, and the result will
be clear and sharp cut writing at a high rate of speed. In the Drawing
I, K, is the inducing apparatus, which may be of any of the well known
forms of magneto-electric or battery inducing apparatus, but preferably 3
should include the circuit changer, Figure 2. The induced current is
continuously flowing in the shunt, and the chemical paper passing over

page_text: the drum D' will not be marked except when the transmitting battery
current of opposite polarity to the local induced current overcomes the
depolarizing induced current. It is obvious that the process may be
reversed, so that the induced current shall do the marking.
In Figure 7 I have indicated a method of rendering the writing clear
and sharp cut by the use of a resistance in a shunt at the receiving end
of a line. R is the resistance; I, S, a single wire induction coil.
When the circuit of the line is through disc C of circuit changer,
roller H, and resistance R, recording stylus and drum to carth, the
greater portion of the transmitting battery current passes through single
wire induction coil I, S, to earth, magnetizing the iron core of the coil.
Now when the line circuit is changed by the circuit changer through
disc C, roller H, recording stylus and drum D¹ to earth E, the most of
the current from the transmitting battery passes that way and the core
of the coil I, S, discharges a depclarizing current in the local circuit of
the shunt thus,-Coil I, S, disc C, roller H, recording stylus drum D³,
and to coil I, S, rendering the writing clear and sharp cut.
I also employ the following method of producing clear and sharp cut
writing upon the recording paper, using any of the well known devices
of perforated paper and styluses for introducing the currents :-First, I
transmit an induced current of the same polarity as the battery current
to be recorded; this I follow instantly by the battery current to be
recorded; then I transmit an induced current of opposite polarity to the
recording battery current, following this by a battery current of opposite
polarity to the recording battery current; or I omit the second or
negative battery current; or I omit the second or negative induced
current.
In operating ocean cables it is of advantage to employ equating
batteries of both polarities, which are introduced in the cable at the
receiving end by any suitable devices. When the recording stylus is
making a continuous mark it is evident that the cable contains a surplus
of the discoloring current, and the receiving operator introduces a
neutralizing current to clear the line. When the recording stylus is
marking imperfectly it is evident that the depolarizing charge in the
cable is too strong, and the operator introduces a current of the same
polarity as the discoloring current.
By using a magnifying glass the increment and decrement of the
currents as indicated by the marks upon the chemical paper, growing

page_text: darker or lighter, may be more easily watched, and the neutralizing
batteries introduced accordingly.
As any of many devices will accomplish the same thing, and the
process is not capable of illustration, I have not attempted to indicate
the necessary apparatus by Drawings.
The batteries may be introduced in a shunt instead of into the cable
itself.
It is obvious that the method of transmission herein described may
be greatly varied.
Instead of employing an induction coil in the manner set forth for
the purpose of clearing a line of tailings I may employ any device or
apparatus, magneto-electric or otherwise, to constantly generate induced
currents forming an induced current battery, and these induced currents
may be transmitted after each battery current to clear the line; or I
may transmit an induced current to effect the chemical discoloration,
and follow that by an induced current of opposite polarity to clear the
line.
Having described the nature of the Invention and the manner of
performing the same, I declare that what I claim as the Invention to be
protected by the herein-before in part recited Letters Patent is,-
First. In chemical telegraphs the combination of a line, main battery,
and contact stylus therefor; a local battery with contact stylus therefor;
the circuit of the local battery through the primary wire of an induction
coil; and a contact stylus throwing the secondary wire of the induction
coil into the line and connecting the line to earth, substantially as set
forth.
Second. The combination with a line, its battery and stylus, of an
induction coil and stylus therefor, connected or connecting the line to
earth, and simultaneously, or nearly so, throwing the secondary induced
current into the line for clearing the same, substantially as set forth.
Third. The combination with a line and its transmitting battery of
an induction coil, the secondary current whereof is thrown into the line
after each signally pulsation as set forth.
Fourth. The method of operating an automatic or chemical telegraph
by first simultaneously, or nearly so, closing the transmitting circuit,

page_text: and the local primary circuit of an induction coil, and then upon
breaking the transmitting circuit and instantly before breaking the local
primary circuit of the induction coil, closing the circuit of the line
through the secondary wire of the induction coil and to an earth, sub-
stantially as and for the purpose specified.
Fifth. Clearing a line of inductive effects or tailings by an induced
current of opposite polarity to the transmitting battery current, which
induced current is not generated by the transmitting battery.
Sixth. The use of an induction coil consisting of two or more wires for
the purpose of clearing a line of inductive effects or tailings.
Seventh. In a chemical telegraph transmitting a battery impulse, and
following it by an induced current by means of a special contact point
or points or row of perforations.
Eighth. In combination with a main‘line circuit and stylus a stylus
connected or connecting to an induction apparatus.
Ninth. The combination of a stylus closing the circuit of a local battery
through the primary wire of an induction coil and a stylus, closing the
circuit of the secondary wire thereof to the line, the local circuit being
broken at or about the instant of completion of the secondary circuit,
substanlially as and for the purposes specified.
Tenth. The combination of a line transmitting battery and metallic
contact point, brush or roller therefor, with a magneto-electric or induc-
tion coil apparatus, giving a current of single polarity and metallic
contact point, brush, or roller therefor, substantially as shown and
described.
Eleventh. The combination of a line magneto-electric or induction coil
apparatus giving a current of single polarity and metallic contact point,
brush, or roller therefor, with a magneto-electric or induction coil
apparatus giving a current of single and opposite polarity to the first
and metallic contact point, brush, or roller therefor, as and for the
purposes specified.
Twelfth. Employing equating batteries of both polarities at the re-
ceiving apparatus, which are introduced into the line, branch, or shunt
at the receiving end, according as the recorded marks are dark and run
together or light and shortened, as set forth.

page_text: .
Thirteenth. In chemical telegraphs the method of producing a clear
sharp record by transmitting, first, a positive induced current; second, a
positive battery current; third, an induced negative current, followed or
not by a negative battery current.
Fourteenth. The combination with a line or circuit of a circuit changer,
commutator, or. current diverter, and two series of apparatus or batteries
composed of different parts or sections, or two parts of one apparatus or
battery, or a single apparatus or battery, the series, sections, part, or
parts referred to being alternately connected to the line by the commu-
tator as and for the purposes specified.
Fifteenth. The combination with a line of a circuit changer, com-
mutator, or current diverter-operating to divide into two or more distinct
impulses independently of the transmitting instrument or battery im-
pulses, the current necessary to form a signal or the integral part of a
signal, substantially as described.
Sixteenth. The electrical circuits, Figures 3, 4, 6, and 7.
Seventeenth. The combination of a circuit changer with a single or
double wire induction coil as set forth.
Eighteenth. The combination of a circuit changer with a resistance,
as set forth.
Nineteenth. Depolarizing the recording stylus by an induced current
in a local circuit, substantially as shown and described.
Twentieth. In a chemical telegraph receiving instrument the combi-
nation with a double shunt circuit of the primary and secondary wires
of an induction coil and resistances, as shown and described.
Twenty-first. A non-inductive resistance composed of a length of
wire arranged in parallel returning layers, substantially as shown and
described.
In witness whereof, I, the said Alexander Melville Clark, have
hercunto set my hand and scal, this Twenty-fifth day of May, in
the year of our Lord One thousand eight hundred and seventy-
fixe