IMPROVEMENTS IN TELEGRAPHIC CIRCUITS
Year: 1875

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 TELEGRAPHIC CIRCUITS."-A communication from
abroad by William Edward Sawyer, of Washington, in the District
of Columbia United States of America.
PROVISIONAL SPECIFICATION left by the said Alexander Melville
Clark at the Office of the Commissioners of Patents, with his
Petition, on the 28th June 1875.
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 TELEGRAPHIC CIRCUITS," to be as
follows:-
This Invention relates to improvements in telegraphic circuits, the
said improvements being more especially designed to be applied to fac-
simile or autographic telegraphs for which I have obtained former

page_text: Letters Patent, but it is obvious that they may be applied to most other
telegraphs, such, for instance, as the Morse and the automatic, and I
therefore do not confine myself to their application to any particular
system.
The main principle of the present Invention consists in a division of
the transmitting battery current, and the placing of that battery at the
receiving end of a line. The result of this application of electric force
is not to free a line of tailings, or the attenuation of impulses transmitted
which may exist to any degree in the line wire, but to prevent those
tailings or attenuations of impulses from producing any effect upon the
receiving instrument.
In order to produce a cut-off action or discoloration of chemical paper
in the receiving instrument it is only necessary that the closing of the
circuit at the transmitting end of a line shall set the current from the
battery at the receiving end to dividing end, a part of it flowing in the
direction of the transmitting end. It is not necessary therefore that an
impulse shall ever reach the transmitting end. It is not necessary that
the current shall travel any distance upon the line wire, but that we
reduce the potential of current. acting upon the receiving instrument,
and to reduce this potential it is merely necessary that the current shall
begin to flow by division towards the transmitting end.
1
In the operation of the Invention I prefer an intensity to a quantity
_current_battery. The battery_which gives the best results is that which
will not supply enough electricity in quantity to work two or more
circuits at the same time: Intensity is desired, and a magneto-electric
or an induced current gives surprising results. In using a carbon
battery, so called, P. greatly prefer that both the carbons and the zincs
shall be of small size.
F
In the accompanying Drawings I have represented the transmitting
and the receiving instruments, cach by a drum and a stylus. Their
places it is obvious may be supplied by any telegraphic mechanism for,
transmitting and receiving, whether for autographic, automatic, or Morse,
transmission.
wollt
In Figure 1 is shown the simple battery dividing circuit; E, E, E, are
carths; C is the transmitting stylus;, D', the transmitting, drum at, for
instance, Washington; D. is the receiving drum; S, the recording,

page_text: stylus; R, are adjustable resistance, and B, the transmitting battery at
New York. Assuming the resistance of the line to be 5,000 ohms, the
artificial resistance R should preferably exceed 5,000 ohms. It will
thus be understood that when the line wire circuit is broken, the
battery B will flow entirely through the stylus S and drum D, producing
action or discoloration of chemical paper, but when the line wire circuit
is closed at the transmitting end the battery current will divide a part
flowing over the line wire, and this division will so weaken the current
flowing through the artificial line as to prevent action or discoloration
at S and D. I may employ condensers or coils, in connection with the
artificial line, and the drum and stylus may be shunted with adjustable
rheostats to regulate the amount of current passing through the
receiving instrument, or with roversed batteries, or with both. ;
1
J
From the description of Figure 1 it will be apparent that the line wire
tailings or battery current attenuations can never affect; the receiving
instrument. The resistance R is so heavy as to send all or nearly all
the tailings to earth through the battery B, forming practically a very
short circuit for the tailings, the only resistance there being, the
resistance of the battery. Thus, it will be seen that the larger the line
wire circuit the less will the line wire tailings, affect the receiving
instrument, for the greater will be the resistance of the artificial. line,
and proportionally the shorter will be the circuit through the battery B
through which the tailings flow. The period of time required for a line
to discharge is therefore of no account, as the action upon the recciving
instrument continues only so long as the line wire circuit is closed, and
the battery dividing and flowing into the line wire, and this action.
ceases just as soon as the line wire circuit is broken, as then the charge
in the line wire begins to return through the battery to carth, and the'
whole of the battery current again flows through the artificial line. To
make my meaning clear the operation of the Invention is comparable
only to a vibration of the battery current backward and forward, which'
vibration is dependent upon the closing and breaking of the line wire
circuit at the transmitting end.
!
In order to secure the best results from the Invention a "circuit;
disturber" should be placed in the artificial line; thus is shown at F in
Figure 2. By "circuit disturber" I mean an arrangement very similar
to any circuit breaking device, but with the contact points so arranged
that the circuit will never be wholly broken, but that the perfection of
1

page_text: contact shall vary, that is to say, I place the metallic contact points
upon the drum band or wheel (referring to the former Letters Patent
above alluded to so) near together, that the contact point bearing upon
them shall make connection with one nearly if not quite as soon as it
leaves another point. The effect of this is the same as though a resist-
ance were placed in the circuit, which resistance varies in amount,
intermittently, with immense rapidity.
In Figure 3 is shown another form of division of the main battery;
current R is the resistance forming the artificial line; the adjustablo
resistance R' and the battery B' are in a local shunt around the receiving
instrument; the battery B¹ effects the recording or discolors the chemical
paper whenever, as before described, the main battery B is diverted in
part to the line wire. The action is so apparent that further description
is unnecessary.
In Figure 4 is shown another method of operation; R is the resistance
forming the artificial line; preferably it should exceed the resistance of
the line wire; at x in the shunt may be placed an adjustable
resistance, or a reversed battery, or an induction coil, or any two or all
of them; R' is a resistance exceeding the resistance of R. When the
line wire circuit is broken so slight a portion of the battery current
passes through the stylus that no record is effected, but when the line
wire circuit is closed at the transmitting end the battery flows through
the stylus and drum in sufficiently greater volume to produce the record.
The line tailing will mainly flow to earth through the resistance R,
owing to the greater resistance in the circuit through R' and B.
In Figures 5, 6, 7, and 8 are indicated various employments of
batteries, etc., at the transmitting end, in connection with the arrange-
ments at the receiving end, already described, and additional to tho
simple circuit, Figure 1. In Figure 5 B³ is a reversed battery, designed
to be of sufficient power to force a perceptible neutralizing portion of its
current over the battery B at the receiving end, and therefore through
the artificial line, thus making more complete the cessation of action of
battery B upon the receiving instrument when the main line circuit
is established.
In Figure C is shown a shunt around the transmitting instrument,
in which a heavy resistance R² is placed. The object of this is to keep
the line wire statically charged by furnishing a constant long circuit for

page_text: the division of battery B at the receiving end. When the contact
between C and D' is made, a shorter circuit being established, the battery
B flows into the line wire in increased volume, thus accomplishing the
necessary division of current to actuate the receiving instrument or
effect the recording.
necessary division or current to actuate the receiving instrument or
effect the recording.
In Figure 7 the resistance and battery are shown combined.
In Figure 8 are shown the battery and resistance in combination with
a primary induction coil.
The application of this Invention to autographic or fac-simile telegraphs
is clearly apparent. By its use, as shown in Figure 9, I am enabled to
duplex the line wire, using one circuit for the chemical discoloration and
the other for the regulation of the apparatus, by means of which the
transmitting and receiving instruments are kept in synchronous motion,
Y at the receiving end is an electro-magnet in a shunt, R' being the
adjustable resistance by which the quantity of line current passing
through the magnet is regulated. At the transmitting end of the line.
wire a is a spring connection b, the two insulated poles of the Morse
battery B. The operation is obvious, the throwing of battery B² into
the line wire being caused by inserting between the two springs a the
electrically separated ends of the battery b. This arrangement may be
attached to any ordinary telegraph key. The circuit at the transmitting
end is the same as in Figure 6. The current proceeding from battery B,
whether over the long circuit of line wire and resistance R³ to earth, or
over the short circuit of line wire C and D' to earth, is not of sufficient
strength to operate the instrument y, but battery B³ is of sufficient
strength, whether flowing through the long or the short circuit, to
affect y. On the other hand battery B will produce no effect upon the
receiving apparatus S and D, because it will flow through the shorter
circuit of battery B to earth.
I do not limit myself to the application of this duplex circuit to any
particular kind of telegraph.
A 11
chome and docovibed herein should be adiustable

page_text: 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 11th December 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-eighth day of June, in the year
of our Lord One thousand eight hundred and seventy-five, in the thirty-
ninth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Alexander Melville Clark, Her special
license that I, the said Alexander Melville Clark, my executors, admini-
strators, and assigns, or such others as I, the said Alexander Melville
Clark, 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, the Channel Islands, and Isle of Man, an Invention for "IMPROVE-
MENTS IN TELEGRAPHIC CIRCUITS," a communication to me from abroad by
William Edward Sawyer, of Washington, in the District of Columbia,
United States of America, upon the condition (amongst others) that I,
the said Alexander Melville Clark, my exccutors or administrators,
by an instrument in writing under my, or their, or one of their hands
and seals, 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
six calendar months next and immediately after the date of the said
Letters Patent.
NOW KNOW YE, that I, the said Alexander Melville Clark, do hereby
declare the nature of the said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement, referenco being had to the accompanying
Sheet of Drawings, and to the letters and figures marked thereon (that is
to say) :-
Ap

page_text: "
1
'
facsimile or autographic telegraph, the 'Invention of the said William
Edward Sawyer, and for which I have obtained Letters Patent, No:
3935, 1874; but it is obvious that they may be applied, to most other
telegraphs (such for instance as the Morse and the automatic), and
I therefore do not confine myself to their application to any particular
system.
j
The main principle of the present Invention consists in a division of
the transmitting battery current, and the placing of that battery at the
receiving end of a line. The result of this application of electric force
is not to free a line of tailings, or the attenuation of impulses trans-
mitted, which
may exist to any degree in the line wire, but to prevent
those tailings or attenuations of impulses from producing any effect upon
the receiving instrument.
:
2
In order to produce a cut-off action or discoloration of chemical paper
in the receiving instrument, it is only necessary that the closing of the
circuit at the transmitting end of a line shall set the current from the
battery at the receiving end to dividing end, a part of it flowing in
the direction of the transmitting end. It is not necessary therefore
that an impulse shall ever reach the transmitting end. It is not
necessary that the current shall travel any distance upon the line wire,
but that we reduce the potential of current acting upon the receiving
instrument, and to reduce this potential it is merely necessary that
the current shall begin to flow by division towards the transmitting
end.
In the operation of the Invention I prefer an intensity to a quantity
current battery. The battery which gives the best results is that which
will not supply enough electricity in quantity to work two or more
circuits at the same time. Intensity is desired and a magneto-electric,
or an induced current gives surprising results. In using a carbon
battery, so called, I greatly prefer that both the carbons and the zincs
shall be of small size.
1.
In the accompanying Drawings I have represented the transmitting
and the receiving instruments each by a drum and a stylus. Their
places, it is obvious, may be supplied by any telegraphic mechanism
for transmitting and receiving, whether for autographic, automatic, or
Morso transmission..

page_text: In Figure 1 is shown the simple battery dividing circuit; E, E, E,
are earths; C is the transmitting stylus; D¹, the transmitting drum at,
for instance, Washington; D is the receiving drum; S, the recording
stylus; R, an adjustable resistance; and B, the transmitting battery
at New York. Assuming the resistance of the line to be 5,000 ohms.,
the artificial resistance R should preferably exceed 5,000 ohms. It will
thus be understood that when the line wire circuit is broken the
battery B will flow entirely through the stylus S and drum D, producing
action or discoloration of chemical paper; but when the line wire circuit
is closed at the transmitting end the battery current will divide, a part
flowing over the line wire, and this division will so weaken the current
flowing through the artificial line as to prevent action or discoloration
at S and D. I may employ condensers or coils in connection with the
artificial line, and the drum and stylus may be shunted with adjustable
rheostats to regulate the amount of current passing through the receiving
instrument, or with reversed batteries, or with both.
From the description of Figure 1 it will be apparent that the line
wire tailings or battery current attenuations can never affect the
receiving instrument. The resistance R is so heavy as to send all or
nearly all the tailings to earth through the battery B, forming practically
a very short circuit for the tailings, the only resistance there being the
resistance of the battery. Thus it will be scon that the larger the line
wire circuit the less will the line wire tailings affect the receiving
instrument, for the greater will be the resistance of the artificial line
and proportionally the shorter will be the circuit through the battery B
through which the tailings flow. The period of time required for a line
to discharge is therefore of no account, as tho action upon the receiving
instrument continues only so long as the line wire circuit is closed, and
the battery dividing and flowing into the line wire, and this action
ceases just as soon as the line wire circuit is broken, as then the charge
in the line wire begins to return through the battery to earth, and the
whole of the battery current again flows through the artificial line.
To make my meaning clear the operation of the Invention is comparable
only to a vibration of the battery current backward and forward, which
vibration is dependent upon the closing and breaking of the line wire
circuit at the transmitting end.

page_text: "
disturber should be placed in the artificial line; this is shown at F
in Figure 2. By circuit disturber I mean an arrangement very similar
to any circuit breaking device, but with the contact points so arranged
that the circuit will never be wholly broken, but that the perfection
of contact shall vary, that is to say, I place the metallic contact points
upon the drum, band, or wheel (referring to the above-mentioned Letters
Patent) so near together that the contact point bearing upon them
shall make connection with one nearly if not quite as soon as it leaves
another point. The effect of this is the same as though a resistance
were placed in the circuit, which resistance varies in amount inter-
mittently with immense rapidity.
In Figure 3 is shown another form of division of the main battery
current; R is the resistance forming the artificial line. The adjustable
resistance R¹ and the battery B' are in a local shunt around the receiving
instrument. The battery B¹ effects the recording or discolors the
chemical paper whenover, as beforo described, the main battery B is
diverted in part to the lino wire. The action is so apparent that furthor
description is unnecessary.
In Figure 4 is shown another method of operation; R is the resistance
forming the artificial line. Preferably it should exceed the resistance
of the line wire. At x in the shunt may be placed an adjustable
resistance, or a reversed battery, or an induction coil, or any two, or all
of them; R' is a resistance exceeding the resistance of R. When the
line wire circuit is broken so slight a portion of the battery current
passes through the stylus that no record is effected, but when the line
wire circuit is closed at the transmitting end the battery flows through
the stylus and drum in sufficiently greater volume to producc
the record. The line tailing will mainly flow to carth through the
resistance R., owing to the greater resistance in the circuit through R¹
and B.
In Figures 5, 6, 7, and 8, are indicated various employments of batteries,
etc., at the transmitting end in connection with the arrangements at
the receiving end already described, and additional to the simple circuit,
Figure 1. In Figure 5 B is a reversed battery designed to be of
sufficient power to force a perceptible neutralizing portion of its current
over the battery B at the receiving end, and therefore through tho
artificial line, thus making more completo the cessation of action of

page_text: All of the resistances shown and described herein should be adjustable,
and preferably should be liquid resistances.
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 by Letters Patent is,―
1st. The method of operating a line of telegraph, consisting in placing
the transmitting battery at or near the receiving end of the line wire,
and effecting the record or actuating the receiving instrument by
making and breaking the line wire circuit at the transmitting end,
whereby the battery current passing through the receiving instrument
is alternately equally or unequally divided and restored to its normal
strength or required maximum value, as set forth.
2nd. The method of operating a line of telegraph consisting of the
employment of two circuits, the line wire circuit and an artificial line
circuit, in the latter of which is placed the receiving instrument, which
is actuated, or in which the record is effected, by causing an increment
and decrement through breaking and making the line wire circuit of the
quantity, or force of the battery current flowing in the artificial line
circuit, as set forth.
3rd. The artificial circuit at the receiving end of line of telegraph,
in which the battery current flows at its required maximum of quantity
or force excepting when a greater or less portion of the battery current
is diverted into the line wire by establishing the line wire circuit, as
set forth.
4th. In operating a line of telegraph the employment of the line
wire to short circuit, or wholly or in part divert the battery current
from an artificial line circuit, in which the receiving instrument is
placed, substantially as shown and described.
In witness whereof, I, the said Alexander Melville Clark, have
hereunto set my hand and scal, this Eleventh day of December,
in the year of our Lord One thousand eight hundred and seventy-
five