IMPROVE- MENTS IN TELEPHONIC CONDUCTORS
Year: 1882

page_text: LETTERS PATENT to Charles William Siemens, of No. 12, Queen Anne's Gate,
Westminster, in the County of Middlesex, for an Invention of "IMPROVE-
MENTS IN TELEPHONIC CONDUCTORS." A communication from abroad by
Frank Jacob, at present on board the steam-ship "Faraday," on the high seas,
PROVISIONAL SPECIFICATION left by the said Charles William Siemens
at the Office of the Commissioners of Patents on the 17th January 1882.
CHARLES WILLIAM SIEMENS of No. 12 Queen Anne's Gate Westminster in the
County of Middlesex. "IMPROVEMENTS IN TELEPHONIC CONDUCTORS." [A com-
munication from abroad by Frank Jacob, at present on board the steam-ship
Faraday," on the high seas.]
"
As telephone instruments are usually arranged, a complete circuit is formed
including in each case a battery, a sending instrument and a receiving instrument,
these two instruments being connected by two insulated wires for the forward and
backward electrical currents respectively. The two wires are often twined together
in one cord this having the effect of preventing interference by induction from
adjacent wires. When a number of sets of telephonic instruments are employed it
is necessary, as they are at present arranged, to provide in the manner described a
complete circuit for each receiver, that circuit requiring the two wires as
stated above. Now the object of this Invention is to render a number of such
pairs of wires capable of supplying an increased number of instruments, by
arrangements such that one receiver can be worked for each wire instead of one
receiver for each pair of wires as at present. In order to illustrate the Invention,
I will suppose that there are two adjacent circuits A and B as at present arranged
each circuit having its battery, its sender, its receiver, and its pair of wires,
making in all four wires. Now I form an additional circuit C with its battery,
sender and receiver using the pair of wires of the A circuit for the forward current
and the pair of wires of the B circuit for the backward current. I also form a
fourth circuit with its battery, sender and receiver, using the four wires of the C
circuit for the forward current and earth for the backward current. In this

page_text: As
manner four sets of instruments can be worked by the use of four wires.
another illustration I will assume as before that there are the two complete circuits A
and B and that there are two other similar adjacent circuits a and b. I form as
above described a third circuit C by using the pair of wires of A for forward and
the pair of wires for B for backward currents, and in a similar manner I form
circuits with 8
another circuit c by like use of the wires of a and b, I have thus
wires. But I can form a seventh circuit D by using the 4 wires of C and the 4
wires of c and an eighth circuit E by using the 8 wires of D and earth for return.
And thus I have 8 circuits effected by the use of 8 wires. In a similar manner I
may connect a greater number of separate circuits so as to form additional circuits,
served respectively by the pairs of wires of two separate circuits, the double pairs
of wires of four separate circuits and so on, the result being generally that a circuit
can be worked for each wire used. Although each pair of wires may thus be made
to serve in several distinct circuits, the instruments of these circuits can never-
theless operate simultaneously without interfering with one another as may be
understood by considering the condition of the A B and C circuits above described
as the first illustration of my method. I will suppose that the circuit A is in use
an electrical current passing forward along one of its wires and returning along
the other. While this is going on, the circuit C is brought into use in which case
a current has to pass forward along both the wires of A and to return by the wires
of B. The effect of this additional current on the two wires of A makes no
difference in their relative condition for by whatever positive potential it increases
the already positive potential of the one, it by the same amount diminishes the
already negative potential of the other, the effect on the instruments which they
operate remaining therefore the same as before. And in like manner when a
greater number of circuits are connected as described, each circuit remains
uninfluenced by currents passing through both its wires to serve other circuits, so
long as both wires of each circuit are thus employed for the passage of a current
of one direction. Although I have stated that in the final combination of a
number of circuits the earth may be used instead of any return wire, yet as the
instruments in such a circuit are liable to considerable interferences from earth
currents and other inductive influences, it is generally preferred not to employ the
earth for telephonic purposes, the circuit of which earth may form a member being
nevertheless available for working electric bells or other signals.

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
17th July 1882.
CHARLES WILLIAM SIEMENS of No. 12 Queen Anne's Gate Westminster in the
County of Middlesex. "IMPROVEMENTS IN TELEPHONIC CONDUCTORS"
A com-
munication from abroad by Frank Jacob at present on board the steam-ship
"Faraday" on the high seas..
;
As telephonic instruments are usually arranged, a complete circuit is formed.
including in each case a battery, a sending instrument and a receiving instrument,
these two instruments being connected by two insulated wires for the forward and
backward electrical currents respectively. The two wires are often twined together
in one cord this having the effect of preventing interference by induction from
adjacent wires. When a number of sets of telephonic instruments are employed it
is necessary, as they are at present arranged, to provide in the manner described a
complete circuit for each receiver, that circuit requiring the two wires as stated
above. Now the object of this Invention is to render a number of such pairs of
wires capable of supplying an increased number of instruments by arrangements
such that one receiver can be worked for each wire instead of one receiver for each
pair of wires as at present. In order to illustrate the Invention I will suppose
that there are two adjacent circuits A and B as at present arranged each circuit
having its battery, its sender, its receiver, and its pair of wires, making in all four
wires. Now I form an additional circuit C with its battery, sender and receiver
using the pair of wires of the A circuit for the forward current and the pair of
wires of the B circuit for the backward current. I also form a fourth circuit with
its battery, sender and receiver, using the four wires of the C circuit for the
forward current and earth for the backward current. In this manner four sets of
instruments can be worked by the use of four wires. As another illustration I will
assume as before that there are the two complete circuits A and B and that there
are two other similar adjacent circuits a and b. I form as above described a third.
circuit C by using the pair of wires of A. for forward and the pair of wires for B
for backward currents, and in a similar manner I form another circuit c by like use
of the wires of a and b, I have thus 6 circuits with 8 wires. But I can form a
seventh circuit D by using the 4 wires of C and the four wires of c and an eighth
circuit E by using the 8 wires of D and earth for return. And thus I have 8
circuits effected by the use of 8 wires. In a similar manner I may connect a
greater number of separate circuits so as to form additional circuits, served
respectively by the pairs of wires of two separate circuits, the double pairs of wires
of four separate circuits and so on, the result being generally that a circuit can be
worked for each wire used. Although each pair of wires may thus be made to
serve in several distinct circuits, the instruments of these circuits can nevertheless
operate simultaneously without interfering with one another as may be understood
by considering the condition of the A B and C circuits above described as the first
illustration of this method. I will suppose that the circuit A is in use an electrical
current passing forward along one of its wires and returning along the other.
While this is going on, the circuit C is brought into use in which case a current
has to pass forward along both the wires of A and to return by the wires of B.
The effect of this additional current on the two wires of A makes no difference in
their relative condition for by whatever positive potential it increases the already
positive potential of the one, it by the same amount diminishes the already
negative potential of the other, the effect on the instruments which they operate
remaining therefore the same as before. And in like manner when a greater number of

page_text: circuits are connected as described, each circuit remains uninfluenced by currents
passing through both its wires to serve other circuits, so long as both wires of each
circuit are thus employed for the passage of a current of one direction. Although
I have stated that in the final combination of a number of circuits the earth may
be used instead of any return wire, yet as the instruments in such a circuit are
liable to considerable interferences from earth currents and other inductive
influences, it is generally preferred not to employ the earth for telephonic purposes,
the circuit of which earth may form a member being nevertheless available for
working electric bells or other signals.
In carrying out this Invention as above described, any known kind of conductors
may be employed, and along with them suitable resistances, condensers, or other
known arrangements for determining the various circuits. Fig: 1 of the accom-
panying Drawings illustrates a simple combination in which the two wires L
connecting two instruments A and A¹ are utilised as a single line with extensions
11¹ of any required length for connecting two other instruments B and B¹, earth E
being used for the return part of the circuit of the latter pair of instruments. The
first instruments A A' are conveniently situated within a bridge in the limbs of
which resistances R are introduced, these resistances being arranged so as to
equalise the potentials on the two sides of each instrument. Fig: 2 illustrates a
combination for working four pairs of instruments with four wires employing
earth for the return part of the circuit of the last pair. In this case the two
pairs A A' and A2 A³ are connected by their double wires L.L' respectively.
These two pairs of wires L L' complete a circuit for a third pair of instruments
CC and the four wires of L L' with earth for return complete a circuit for a
fourth pair of instruments D D'. The instrumes A A', A2 A³ C C¹, are situated
in bridges with resistances R arranged in the limbs of the bridges. As stated
above it is usual to protect telephonic conductors against interference by induction
by twining together the pairs of wires forming their respective circuits. When
two such pairs are combined to operate for another circuit it is of advantage also
to twine together the two strands each consisting of a twined pair thus producing
a strand which in its turn may be twined with a similar strand when four pairs are
combined and so on according to the number of pairs of wires entering into the
combination.
Having thus described the nature of the said Invention and in what manner the
same is to be performed, as communicated to me by my correspondent
I claim
The herein described method of electrically connecting several sets of telephonic
instruments by employing the double conductors for one set as a single conductor
for another set, and multiples of such double lines as single lines.
In witness whereof I the said Charles William Siemens have hereunto set my
hand and seal this Thirteenth day of July in the year of our Lord One
thousand eight hundred and eighty-two.