IMPROVEMENTS IN THE METHOD OF TRANSMITTING TELEGRAPHIC SIGNALS BY SUBMARINE OR OTHER INSULATED ELECTRIC CONDUCTORS, AND APPARATUS FOR THAT PURPOSE
Year: 1874

page_text: LETTERS PATENT to Charles William Siemens, of No. 3, Great George
Street, Westminster, in the County of Middlesex, for the Invention
of "IMPROVEMENTS IN THE METHOD OF TRANSMITTING TELEGRAPHIC SIGNALS
BY SUBMARINE OR OTHER INSULATED ELECTRIC CONDUCTORS, AND APPARATUS
FOR THAT PURPOSE."-A communication from abroad by Dr. Ernst
Werner Siemens, of Berlin, in the German Empire.
Sealed the 2nd June 1874, and dated the 16th April 1874.
PROVISIONAL SPECIFICATION left by the said Charles William
Siemens at the Office of the Commissioners of Patents, with his
Petition, on the 16th April 1874.
I, CHARLES WILLIAM SIEMENS, of No. 3, Great George Street,
Westminster, in the County of Middlesex, do hereby declare the nature
of the said Invention for "IMPROVEMENTS IN THE METHOD OF TRANSMITTING
TELEGRAPHIC SIGNALS BY SUBMARINE OR OTHER INSULATED ELECTRIC CONDUCTORS,
AND APPARATUS FOR THAT PURPOSE," to be as follows :-
This Invention relates to a method of and apparatus for transmitting
telegraphic signals by submarine or other insulated electric conductors.

page_text: The chief object of the Invention is to provide means of transmitting
signals in rapid succession and with precision, a current of electricity of
one and the same direction being always maintained in the conductor
or line. For this purpose both ends of the line are connected with
batteries or other sources of electric power, the one end of the line being
connected to the one pole of its battery and the other end of the line being
connected to the opposite pole of the other battery, and the remaining
poles of both batteries being connected to earth, so that a current
always flows in one direction through the line and batteries; suitable
resistances are also provided to be introduced into the circuit at either or
both ends of the line as will hereafter be described.
A similar result may also be obtained by the use of only one battery
connected to one end of the line, the other end of the line being
connected to earth with or without suitable resistances.
It is preferred to keep the line or the greater part of it always 1
positively charged as preservative of its insulation.
A receiving apparatus is placed at any point of the circuit at the
receiving station and connected to carth, either directly or through
suitable resistances, condensers, or batteries, or combinations of these.
It is preferred to adjust such resistances or batteries or both in such a
balance to the ordinary electrical condition of the line that no current
shall pass through the receiving instrument except when the electrical
condition of the line is disturbed for the purpose of signalling. When
a battery is employed for this adjustment of the receiving instrument it
may be a portion of the main battery which is connected to the line, a
a branch from the said battery being connected to the receiving
instrument, so that it may be influenced by a certain number of the
cells or a certain part of the power of such battery; or without the
use of a battery the receiving instrument is connected to a point of
the circuit where the tension or electric potential in the ordinary
condition of the line is rendered neutral by the introduction of suitable
resistances.
The signalling is effected by altering the electric potential at the sending
end of the line without altering the sign of the electrical charge there.
The potential at the point connected to the receiving instrument is thus
altered, and the receiving instrument is brought into action. Tho
potential at the sending station is altered, either by increasing or

page_text: diminishing it. This may be effected either by inserting into or cutting
out of the circuit by shunt or otherwise portions of the battery power,
or by cutting out or inserting portions of the resistances. Or condensers
may be provided that can be charged to measured tension, and such
condensers can be connected to the line when required, so as cither to
add to or deduct from the potential existing in it. This alteration of
potential at the sending end of the line produces on the receiving
instrument an effect such that if in the case of increase it acts as if
operated on by a positive current, in the case of diminution it acts as if
operated on by a negative current.
By this arrangement, when the electric condition of the line has been
disturbed for the purpose of signalling, its normal condition is more speedily
restored, and the clectric force acting on the receiving instrument is
influenced for a shorter time and to a less oxtent by the residuary action of
preceding signals than is the case when the sign of the electrical charge
of the line is reversed, or when the line is disconnected from carth.
Thus the speed of transmission is increased, as the loss of time is avoided
which usually attends the change of electrification of the line from
positive to negative, or vice versa. When the receiving instrument acts
on a chemical or electro-magnetic writer, so as to make two rows or sets
of marks corresponding respectively to positive and negative currents,
the interference of an earth current can generally be detected before it
becomes of such force as to vitiate the signals, by the greater strength of
the one set of marks and the diminished strength of the other set. Such
difference of strength can be allowed for and compensated by altering
the resistance or the battery power applied to the line, so as to correct
the addition to or the deduction from the power of the line current
caused by the interference of the earth current, and such variation may
be applied to effect the correction automatically.
An electrical impulse sent into the line at the sending station shews
itself at the receiving station like a wave of force gradually swelling to
its maximum, and then gradually diminishing, displacing the point of
neutral tension in the one direction or the other, so that cach impulse
affects for a certain time the receiving instrument, and also influences
succeeding impulses. In order to shorten these waves and to diminish
their mutual influence on each other it is preferred to compose each
signal of two or more impulses following each other in the same direction
but preferably of different duration and intensity, thus producing an

page_text: effect corresponding to that usually obtained by successive positive and
negative impulses.
The impulses transmitted from the sending station may be made to
act on the receiving instrument in various ways.
-
According to one method the line is at its point of neutral tension
connected directly to the receiving instrument which is connected to
earth. In this case the impulse acts on the receiving instrument as if
it were a positve or a negative current in the manner already described; or
the line is connected to the one coating of a condenser, the other
coating of which is connected to carth through the receiving instrument.
In this case the impulse acts on the receiving instrument as a current of
the one direction followed by a current of the other direction,
corresponding respectively with the wave-like alteration of the charge in
the condenser. Or the receiving instrument may be connected as above
described to a condenser, and also by a shunt circuit through a suitable
resistance to the point of neutral tension of the line, so as to be acted on
by the direct impulse from the line and also by the derived impulse from
the condenser. In the ascending branch of the wave of force these actions
support cach other, combining to render the effect stronger, and they
weaken each other in the descending branch, and thus if the resistance
and the capacity of the condenser be suitably proportioned, the principal
part of the descending branch of the wave can be cut off or can be so
much weakened as to prevent it from affecting even very sensitive
receiving instruments. Each signal may thus be rendered more precise,
and reliable signals may be obtained even from impulses that are not
entirely independent of each other.
The resistance applied to the line at the receiving station may consist
wholly or partially of the one wire of a double coiled induction coil, the
other wire of which is closed through the receiving instrument. When
this form of resistance is adopted the current set up by induction may
be made to intensify the action on the receiving instrument, and to
shorten the duration of the effect of the acting current, giving a
result similar to that described above as being obtained from the use
of the condenser.
The connections to the line may be arranged so as to make the point
of neutral tension coincide with the middle of the line, and yet to
maintain the receiving instruments in a state of inaction unless when

page_text: signals are transmitted. The nature of such connections may be
understood from the following example:-The line is connected at each
of its ends through a resistance equivalent to that of half the line to a
branch point. From this branch point another resistance also equivalent
to half the line connects to the battery pole, and a conductor connects
through the receiving instrument to a point in the battery, such that
two-thirds of its force are in this connection to the receiving instrument.
Under these conditions the receiving instruments remain in equilibrium
except when the battery power passing through them and to the line is
altered by increase or diminution for the purpose of signalling. Similar
conditions may be established by varying the proportions of battery
power and of resistance.
By substituting sensitive galvanoscopes for receiving instruments or
connecting such galvanoscopes to them, the position of a fault in a
cable may be determined by adjusting the resistances at each end of the
line so as to restore the galvanoscopes to a neutral condition.
By varying only those parts of the resistances which are in immediate
connection with the cable, the distance of the fault from the middle of
the cable can be at once determined, and by maintaining those resistances
in their altered condition, causing the fault to coincide with the point of
neutral tension, the cable in many cases may still be worked.
Although the method of signalling above described as being effected
by additions to or deductions from the electric potential at the sending
end of the line is in some respects to be preferred, yet it may be readily
understood that while the line remains always charged with electricity
of the same sign, distinction of signals may be obtained not by additions
to as contrasted with deductions from the potential, but by greater or
less additions to or by less or greater deductions from that potential, the
receiving instrument being adjusted so as to be worked by such variations:
of the electric force.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Charles William Siemens in the Great Seal Patent
Office on the 16th October 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
WILLIAM SIEMENS, of No. 3, Great George Street, Westminster, in the
County of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent bearing date the Sixteenth day of April, in the year of
our Lord One thousand eight hundred and seventy-four, in the thirty-
seventh year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Charles William Siemens, Her special
licenso that I, the said Charles William Siemens, my executors, admini-
strators, and assigns, or such others as I, the said Charles William
Siemens, my cxccutors, 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 Inven-
tion for "IMPROVEMENTS IN THE METHOD OF TRANSMTTING TELEGRAPHIC SIGNALS
BY SUBMARINE OR OTHER INSULATED ELECTRIC CONDUCTORS, AND APPARATUS FOR
THAT PURPOSE," a communication to me from abroad by Dr. Ernst
Werner Siemens, of Berlin, in the German Empire, upon the condition
(amongst others) that I, the said Charles William Siemens, my
executors 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 Charles William Siemens, 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 thereof, reference being had to the accom-
panying Sheet of Drawings, and to the figures and letters marked
thereon, that is to say :-
This Invention relates to a method of, and apparatus for, transmitting
telegraphic signals by submarine or other insulated electric conductors.

page_text: The chief object of the Invention is to provide means of transmitting
signals in rapid succession and with precision, a current of electricity
of one and the same direction being always maintained in the conductor
or line. For this purpose both ends of the line are connected with
batterics or other sources of electric power, the one end of the line.
being connected to the one pole of its battery and the other end of the
line being connected to the opposite pole of the other battery, and the
remaining poles of both batteries being connected to earth, so that a
current always flows in one direction through the line and batteries;
suitable resistances are also provided to be introduced into the circuit at
either or both ends of the line, as will hereafter be described.
A similar result may also be obtained by the use of only one battery
connected to one end of the line, the other end of the line being con-
nected to carth with or without suitable resistances.
It is preferred to keep the line, or the greater part of it, always
positively charged as preservative of its insulation.
A receiving apparatus is placed at any point of the circuit at the
receiving station and connected to earth either directly or through
suitable resistances, condensers, or batteries, or combinations of these.
It is preferred to adjust such resistances or batteries or both in such
balance to the ordinary electrical condition of the line that no current
shall pass through the receiving instrument except when the electrical
condition of the line is disturbed for the purpose of signalling. When
a battery is employed for this adjustment of the receiving instrument,
it may be a portion of the main battery which is connected to the
linc, a branch from the said battery being connected to the receiving
instrument, so that it may be influenced by a certain number of the
cells or a certain part of the power of such battery. Or, without the
use of a battery, the receiving instrument is connected to a point of
the circuit, where the tension or clectric potential in the ordinary
condition of the line is rendered neutral by the introduction of suitable
resistances.
The signalling is effected by altering the electric potential at the
sending end of the line, without altering the sign of the electrical
charge there. The potential at the point connected to the receiving

page_text: action. The potential at the sending station is altered either by
increasing or diminishing it. This may be effected either by inserting
into or cutting out of the circuit, by shunt or otherwise, portions of the
battery power, or by cutting out or inserting portions of the resistances.
Or condensers may be provided that can be charged to measured
tension, and such condensers can be connected to the line when required,
so as either to add to or deduct from the potential existing in it. The
alteration of potential at the sending end of the line produces on the
receiving instrument an effect such, that if in the case of increase, it
acts as if operated on by a positive current, in in the case of diminution,
it acts as if operated on by a negative current.
By this arrangement, when the electric condition of the line has been
disturbed for the purpose of signalling, its normal condition is more
speedily restored, and the electric force acting on the receiving instru-
ment is influenced for a shorter time and to a less extent by the
residuary action of preceding signals than is the case when the sign of
the electrical charge of the line is reversed, or when the line is dis-
connected from earth. Thus the speed of transmission is increased, as
the loss of time is avoided, which usually attends the change of
electrification of the line from positive to negative, or vice versa. When
the receiving instrument acts on a chemical or electro-magnetic writer,
so as to make two rows or sets of marks, corresponding respectively to
positive and negative currents, the interference of an earth current can
generally be detected before it becomes of such force as to vitiate the
signals by the greater strength of the one set of marks and the
diminished strength of the other set; such difference of strength can be
allowed for and compensated by altering the resistance or the battery
power applied to the line, so as to correct the addition to or the
deduction from the power of the line current caused by the interference
of the earth current, and such variation may be applied to effect the
correction automatically.
An electrical impulse sent into the line at the sending station shews
itself at the receiving station like a wave of force, gradually swelling
to its maximum and then gradually diminishing, displacing the point
of neutral tension in the one direction or the other, so that cach
impulse affects for a certain time the receiving instrument and also

page_text: to diminish their mutual influence on each other, it is preferred to
compose each signal of two or more impulses following each other in
the same direction, but preferably of different duration and intensity,
thus producing an effect corresponding to that usually obtained by
successive positive and negative impulses.
The impulses transmitted from the sending station may be made to
act on the receiving instrument in various ways.
According to one method the line is at its point of neutral tension
connected directly to the receiving instrument, which is connected to
earth. In this case the impulse acts on the receiving instrument as
if it were a positive or a negative current, in the manner already
described. Or the line is connected to the one coating of a condenser,
the other coating of which is connected to earth through the receiving
instrument. In this case the impulse acts on the receiving instrument
as a current of the one direction followed by a current of the other
direction corresponding respectively with the wave-like alteration of the
charge in the condenser. Or the receiving instrument may be con-
nected, as above described, to a condenser, and also by a shunt circuit
through a suitable resistance to the point of neutral tension of the line,
so as to be acted on by the direct impulse from the line and also by the
derived impulse from the condenser. In the ascending branch of the
wave of force these actions support each other, combining to render
the effect stronger, and they weaken each other in the descending
branch. And thus, if the resistance and the capacity of the condenser
be suitably proportioned, the principal part of the descending branch
of the wave can be cut off, or can be so much weakened as to prevent
it from affecting even very sensitive receiving instruments. Each
signal may thus be rendered more precise, and reliable signals may be
obtained even from impulses that are not entirely independent of cach
other.
The resistance applied to the line at the receiving station may consist
wholly or partially of the one wire of a double coiled induction coil, the

page_text: The accompanying Drawings shew diagrammatically arrangements of
batteries and resistances in connection with a submarine cable or other
long telegraphic line for the purpose of operating therewith as above
described.
According to the arrangements shewn in Fig. 1 the line wire L, 1, is
at the one end L connected to the copper pole of a battery B, the zinc
pole of which is connected to earth. The other end is connected
through a resistance 1, R, to the zinc pole of another battery B', the
copper pole of which is connected to earth. The battorics and the
resistances of the line and of 1, R, are so proportioned that the tension
at L being represented by an ordinate L, a, and that at R by R, 6, the
line a, 1, b, joining the extremities of those ordinates passes through the
end of the line, which is therefore the point of neutral tension. A.
receiving instrument I in a line connecting to earth will remain
unaffected, while the electrical condition of the line remains unchanged,.
but upon increasing or diminishing the electrical potential at L, the
point of neutral tension being thereby shifted from 7, the instrument will
be affected according to the alteration.
Fig. 2 shows diagrammatically arrangements by which receiving
instruments I can be acted on when they are not connected to points
of neutral tension. In this case resistances L, R, and 1, r, are applied.
at both ends of the line L, 1, between the line and the batteries.B, so
that if ordinates R, G, r, g, represent the electrical potentials at the
batteries the line G, m, g, joining their extremities and crossing the line
at m determines by the ordinates L, a, 1, b, the electrical potentials at
the ends of the line, which are necessarily less than the potentials at the
batteries. The instrument I is at each end placed in a circuit connecting
the end of the line with some point d of the battery, such that the
potential at d balances that at L or 7, the instrument I being thus
neutral. But if the circuit through I be connected to some point For
f of the battery, where the potential is greater or less; then the
instrument I will be proportionally affected.
According to the arrangement shewn diagrammatically in Fig. 3 the
resistance R applied at the end of the line consists of the primary coil
of an inductor, the secondary coil of which r as well as the line at its
point of neutral tension is connected through the receiving instrument I
to earth. When the potential at the end of the line is altered the

page_text: are connected to the receiving instruments, substantially in the manner
and for the purposes herein set forth.
In witness whereof, I, the said Charles William Siemens, have here-
unto set my hand and seal, this Twelfth day of October, in the
year of our Lord One thousand eight hundred and seventy-
four.