Improvements in the Construction and Arrangement of Electrical Conductors, Mainly Applicable to Telephonic Purposes.
Year: 1886

page_text: Improvements in the Construction and Arrangement of Electrical
Conductors, Mainly Applicable to Telephonic Purposes.
I, WILHELM CHRISTIANI, of No. 16 Schillstrasse, Berlin in the German Empire,
Government Inspector of Telegraphs, do hereby declare the nature of this invention
to be as follows:--
In telephonic transmission to ensure a transmission of the speech as distinct as
possible, the conductors must be so constructed firstly, that the power of conduction
and insulation does not sink below a certain minimum; secondly that the charging
capacity is as small as possible and thirdly, that in the conducting parts of the cables
no induction shall occur which results in a loss of power.
For the purpose of constructing cables that fulfil these conditions use is made,
according to the present invention, of the fact that two currents crossing each other
at right angles have no inducing effect upon each other, for which purpose the con-
ductors are formed of several wires which are coiled together round a longitudinal
axis at an angle of 45° thereto. Thus all coils of the contiguous conductors form at
their contact with each other an angle of 90°. Such a conductor consists of at
least two insulated metal wires as shewn at Fig. 1, which are twisted together
as closely as possible without a core so that the coils form with the longitudinal axis
an angle of 45°. The conductor may, however, be composed of a greater number of
wires, these being twisted closely round a core of iron wire or other material. For
three wires a core must be used of the same thickness as the insulated wires, for four
wires, a core must be taken of double thickness, and so on, as, for instance, shewn at
Figs. 2 and 3. The core having thus several wires twisted thereon is enveloped by a
covering of hemp or jute, as many wires being taken to form the cable as circum-
stances may require. The protective covering of such cables does not differ from
ordinary constructions. The separate strands can either be used as single conductors,
all the wires of cach conductor being connected in parallel arc, or they may be
formed into double conductors which, where necessary, are connected with the single
terminal conductors by the employment of connections to be presently explained.

page_text: Of course, such cables can also be used in telephonic communication with com-
plete circuit of outward and return wire for every subscriber, and they are therefore
particularly applicable in such cases where the above-ground conductors have to be
gradually done away with, or where the system of metallic return conductors is to
be adopted. So long as the double conductors of the cables are used in combination
with single overhead conductors, the reversal of the current in the second cable
conductor which has with the actual speaking conductor no conducting connection,
is effected entirely by induction, and in order to support the inductive action in
each wire of the cable, induction coils are formed and brought into the circuit in
such manner that the electro-magnets of the switch boards at which the double con-
ductors terminate, are provided with double bifiliar coilings. By including the
second coiling of the electro-magnets in the closed circuit of the second conductor
belonging thereto, the detrimental property of the switches in decreasing the sound
in the speaking circuit is prevented; also the induction produced between the con-
tiguous coils in the ordinary switch electro-magnets, which also has a detrimental
action, is prevented. The arrangement of the connecting conductor in this case is
shewn at Fig. 4. The overhead conductor L is connected with the wire a of a cable,
while the wire 6 of the same conductor is connected to earth E. At the central
station the wires a and b are connected separately with the two coilings ww of the
switch electro-magnets, the other ends of which are also connected to earth. The
coupling of the speaking apparatus for communicating with the subscribers is
effected circularly between wires a and b in the manner indicated by dotted lines.
Two branch conductors are on the other hand connected together with the inclusion
of one or both switches as indicated at Fig. 5 for which double stopper wires may be
used. In a similar manner the communication through two central stations, is
effected in using a double connecting conductor between these stations. If the two-
wire conductors are only to be used for connecting two central stations, while for
the branch conductors single cable or overhead wires are available, the connections
may be arranged as at Fig. 6. K K are the switch electro-magnets with double coils.
Another arrangement is shewn diagrammatically at Fig. 7 for the case where the
switch electro-magnets are arranged in shunt circuits. The extent of resistance of
the shunt circuits must not be taken too small in this case if importance is laid upon
a direct interchange of battery signals between the end stations. If necessary, con-
densers may be also included in the earth connections of the switch electro-magnets.
If, however, this is dispensed with, it may, under certain circumstances, be advan-
tageous to connect the branch conductor at central station I with the cable wire a,
while at II it is connected to cable wire b. In the latter case, two induction
transmissions arranged in parallel arc are obtained, which admit of a much stronger
transmission of sound than the arrangement in sequence.
For the better utilisation of such conductors and for conveying simultaneously
two different communications in each cable wire or in each connection the following
arrangements are employed.
For the communication between the two central stations in a double wire already
in use, the arrangement of current as shewn at Fig. 8 is employed, based on the use
of intermediate apparatus with double coilings. In this case if, in speaking between
the end stations, the two conductors of the connecting arrangement are traversed by
equal but oppositely directed currents, the action of the currents in the intermediate
apparatus FF neutralise each other, while, in speaking by means of an intermediate
apparatus, currents having the same direction are induced in the connecting con-
ductors which only call the other intermediate apparatus but which neutralize each
other in the end apparatus. As transmitters in the intermediate apparatus may be
used either telephones with double coilings or microphones provided with two
induction coils arranged in parallel arc. The primary coils of these are arranged
side by side in the circuit of the microphone battery, while the secondary coils are
situated separate in the two conductors. In a similar way also the connection shewn
at Fig. 6 may be arranged for double speaking by the use of doubly coiled inter-
medtaie apparatus.

page_text: Another connection which permits of a more general application with the use of
the usual system of apparatus is shewn at Fig. 9. In this case K¹ and K¹ are the
switch electro-magnets of the connecting conductors converted into induction coils
which, on the one hand, are connected in such manner with the subscribers con-
ductors or with earth, and, on the other hand, with the two connecting con-
ductors a and b, that for the communication between the conductors the conect-
ing conductor a is included, while for the communication between ¹¹ the connect-
ing conductor b is included. In order to ensure that the conductor will convey
oppositely directed currents through the wires of the connecting arrangement, while
the conductor sends parallel directed currents, the coilings of the induction
bobbin K are inserted in the same direction, while those in the induction bobbin K¹
are inserted in opposite directions. By the help of induction transmissions further
double speaking connections may be carried out on the same principle as shewn
diagrammatically in Fig. 10.
JJ are ordinary induction bobbins the primary coils of which are included in
one of the speaking conductors, while the secondary spirals are either arranged in
parallel arc or in sequence and are connected with the speaking conductors 1 11.
The indicated connections are, however, not only applicable for the cables first
described but may also be employed in connection with ordinary cables having
double conductors as also with overhead conducting connections. In the latter
case it is necessary to arrange the two wires belonging together as near as possible
to each other and as far as possible from the other wires, and in such manner that
they are affected as uniformly as possible by the inducing influences of the con-
tiguous conductors. In addition to the application of the before described cables
to telephonic systems they may also be employed for telegraphic conductors or
other electrical conductors in which the same conditions are required. Lastly, the
same system may also be employed for constructing overhead conductors of non-
insulated wires free of induction.
ABEL & IMRAY,
8, Southampton Buildings, London, W.C.
Agents for the Applicant.

page_text: Improvements in the Construction and Arrangement of Electrical
Conductors, Mainly Applicable to Telephonic Purposes.
I, WILHELM CHRISTIANI, of No. 16 Schillstrasse, Berlin in the German Empire,
Government Inspector of Telegraphs, do hereby declare the nature of this invention
and in what manner the same is to be performed to be particularly described and
ascertained in and by the following statement;-
This invention has for its object the construction of single and double conductors
for electrical purposes in particular for telephonic lines, free from induction, as
also a new arrangement of double conductors in such manner that one wire thereof
is used for speaking in the usual manner with earth contacts at both ends, while
the second wire is employed for neutralising the inductive action upon the con-
tiguous conductors.
In constructing such conductors free from induction they are made in the form
of solenoids, the coils of which have such an angle of inclination to the longitudinal
axis that two contiguous solenoids do not have any inductive action upon each
other. The extent of such angle of inclination at which the induction disappears
depends upon the size of the coils and their distance from each other, and must be
at least 45°.
If two solenoids, wound in the same direction and having their coils
approximately perpendicular to the longitudinal axis, are placed parallel to each
other, then a current passing through the one solenoid will, as is well known,
produce in the other an induced current having the same direction. If now the
solenoid coils be gradually drawn out in the direction of the longitudinal axis until
they become straight wires, the coils of the two solenoids will be made to form
angles with each other that will gradually increase from 0° to 180°, and the
induced current in the one solenoid will vary in a corresponding manner, in as
much as it will at first gradually decrease, until at a certain medium point it
becomes zero and then it will be converted into a current of the reverse direction,
of gradually increasing strength, attaining its maximum when the wires are
stretched out. The middle position in which the induced current becomes zero is
approximately reached when the separate coils of the solenoid wires form an angle
of at least 45° with the longitudinal axis, as in this position the contiguous half
coils of the two solenoids cross each other at a right angle, and can therefore not
have any inductive action upon each other. But as the half coils of the two
solenoids that lie apart from each other also participate in the inductive action, it
is in the most cases necessary to somewhat increase this minimum value of 45°
in order to remove all induction, and the increase of this minimum value may in
some cases amount to as much as 60°, because the distances of the solenoid coils
from each other and consequently the extent of the inductive action. will vary
according to the dimensions of the conductors, and of the insulating coverings
thereof, if such be used. There will also have to be considered, in determining the
angle in question, the fact that the inductive action of two contiguous solenoids
upon their outer semi-coils will be more or less neutralised by the inner semi-coils
lying between them, and which form a metallic partition.

page_text: Solenoids free from induction such as above described may be constructed either
of uncovered or of insulated wires. Fig. 1 of the accompanying drawings shews
two such solenoids consisting of wires coiled at an angle of 45°. As this coiling
of a single wire at an angle of 45° presents considerable practical difficulties it is
preferable to employ two or more wires coiled round each other, or round a central
non conducting core. Fig. 2 shews two wires coiled helically round each other in
this manner; Fig. 1 shews a single wire coiled round a core; Fig. 3 shews
three wires and Fig. 3 shews four wires coiled round a core, the upper portion of
some of the coils being in each case cut away so as to shew that while in the plan
view the wires of the two contiguous conductors appear to be parallel to each other,
the contiguous parts of the coils in reality lie in opposite directions and conse-
quently cross each other at right angles.
When using uncovered wires, such as are employed exclusively for overhead
lines, the conductors are preferably formed by coiling two wires together at an
angle of 45° as at Fig. 2.
For producing cables, the conductors may either be first coiled together and then
insulated, or they may be first insulated and then coiled. In the latter case
multiple wire lines are obtained of which the separate wires are either connected
in parallel are to form single conductors, or they are arranged as outward and
return conductors, or they may be used in combination with single end conductors
by the employment of connections to be presently described. In the arrangements
for this last named purpose the reversal of the current in the second conductor of
the cable, which has no conducting connection with the telephone conductor
proper, is generally effected entirely by induction, and in order to support the
inductive action in each wire of the cable, induction coils are formed and brought
into the circuit in such manner that the electro-magnets of the switch boards at
which the double conductors terminate, are provided with double bifiliar coilings,
that is to say with coils formed by the simultaneous coiling of two wires upon a
common core. By including the second coiling of the electro-magnets in the closed
circuit of the second conductor belonging thereto, the detrimental property of the
switches in decreasing the sound in the speaking circuit is prevented; also, the
induction produced between the contiguous coils in the ordinary switch electro-
magnets, which also has a detrimental action, is prevented. The arrangement of
the connecting conductor in this case is shewn at Fig. 4. The overhead conductor
B is connected with the wire a of a cable, while the wire of the same conductor
is connected to earth E. At the central station the wires a and b are connected
separately with the two coilings w w of the switch electromagnets, the other ends
of which are also connected to earth. The coupling of the speaking apparatus
for communicating with the subscribers is effected circularly between wires a and b
in the manner indicated by dotted lines. Two branch conductors are on the other
hand connected together with the inclusion of one or both switches as indicated
at Fig. 5 for which double stopper wires may be used. In a similar manner the
communication through two central stations is effected in using a double_con-
necting conductor between these stations. If the two wire conductors are only to
be used for connecting two central stations, while for the branch conductors single
cable or overhead wires are available, the connections may be arranged as at Fig. 6.
KK are the switch electro-magnets with double coils.
Another arrangement is shewn diagrammatically at Fig. 7 for the case where the
switch electro-magnets are arranged in shunt circuits. The extent of resistance
of the shunt circuits must not be taken too small in this case if importance is laid
upon a direct interchange of battery signals between the end stations. If
necessary condensers may be also included in the earth connections of the switch
electro-magnets. If, however, this is dispensed with, it may, under certain
circumstances be advantageous to connect the branch conductor at central station
I with the cable wire a, while at II it is connected to cable wire b. In the latter
case the two speaking stations are not connected by an uninterrupted conductor but.
the switch electro-magnets form two induction transmissions which are however not

page_text: connected in series but in parallel arc and consequently afford a powerful trans-
mission of sound.
For the better utilisation of such double wire conductors and for conveying
simultaneously two different communications in each cable wire or in each connec-
tion the following arrangements are employed.
For the communication between the two central stations in a double wire already
in use, the arrangement of current as shewn at Fig. 8 is designed based on the
use of intermediate apparatus with double coilings. In this case if, in speaking
between the end stations, the two conductors of the connecting arrangement are
traversed by equally strong but oppositely directed currents, the action of the
currents in the intermediate apparatus F F neutralise each other, while in
speaking by means of an intermediate apparatus currents having the same
direction are induced in the connecting conductors which only call the other
intermediate apparatus but which neutralise each other in the end apparatus. As
transmitters in the intermediate apparatus may be used either telephones with
double coilings or microphones provided with two induction coils arranged in
parallel are. The primary coils of these are arranged side by side in the circuit
of the microphone battery, while the secondary coils are situated separate in the
two conductors. In a similar way also the connection shewn at Fig. 6 may be
arranged for double speaking by the use of doubly coiled intermediate apparatus.
Another connection for double speaking which permits of the use of the usual
system of apparatus is shewn at Fig. 9. Here K and K are the switch electro-
magnets of the conductors a b converted into induction coils. Of the two coilings
of the switch magnets K one is introduced between the end conductor and the
conductor and the other between the conductor b and earth, while of the two
coils of the switch magnets K¹ one in introduced between the conductor and the
conductor and the other between the conductor a and earth. The arrangement
is in this case such that with the switch magnet K the connection of the con-
ductor a bare situated at one and the same end of the magnet, while with the
switch magnet K¹ the connections of the conductors are at the opposite ends, so
that the currents coming from the conductors a and b flow through the coils of K
in the same direction and through the coils of K¹ in contrary directions.
Modifications of this arrangement are shewn at Figs. 9 and 9b, polarised switch
magnets being employed in the latter case.
By the help of induction transmission further double speaking connections may
be carried out on the same principle as shewn diagrammatically on Fig. 10.
Jare ordinary induction bobbins the primary coils of which are included in
one of the speaking conductors, while the secondary spirals are either arranged in
parallel arc or in scries and are connected with the speaking conductors.
The indicated connections are, however, not only applicable for the conductors
free from induction first described but may also be employed in connection with
ordinary cables having double conductors as also with overhead conducting con-
nections with ordinary conducting wires. In the latter case it is necessary to
arrange the two wires belonging together as near as possible to each other
and as far as possible from the other wires, and in such manner that they are
affected as uniformly as possible by the inducing influences of the contiguous
conductors.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is
1. For the production of electrical conductors of all kinds free from induction,
the use of solenoid-like coiled conducting wires in which, for the purpose of
avoiding inductive action upon a contiguous conductor of the same construction,
the angle of inclination of the coils to the longitudinal axis of the conductor is at
least equal to 45°, substantially as herein described.

page_text: 2. In the application of conducting wires such as are referred to in the preceding
claim, to cables with solenoid-like double conductors, the combination of the two
conducting wires of the double conductor with the double bifiliar coiled switch
electro-magnets in such manner that the one coiling of the switch magnet is in-
cluded in the speaking conducting wire while the other is included in the induction
conducting wire (compensation conductor) of the same double conductor, sub-
stantially as herein described.
3. In the application of cables with solenoid-like double conductors such as are
referred to in the previous claim, in combination with single overhead end con-
ductors, the use of the arrangements herein described with reference to Figs. 4 to 7,
in which one wire of the double conductor always serves for conveying the speaking
currents while at the same time currents of reverse direction are produced by
induction in the second wire, substantially as herein described.
4. In the application of cables with solenoid-like double conductors such as are
referred to in the second claim, the use of double conductors for double speaking,
the apparatus being connected in such manner that for the one speaking currents
are employed that flow in the same direction in both wires, while for the second
speaking currents are used that flow in opposite directions in the two wires, sub-
stantially as herein described with reference to Figs. 8 to 10 of the drawings.
5. In combination with the arrangement referred to in the fourth claim for
double speaking, the use of telephones with double coilings and of microphones
with double induction coil substantially as herein described.
ABEL & IMRAY,
Agents for the Applicant.