ANTI INDUCTION SYSTEM FOR TELEGRAPH CABLES AND WIRES
Year: 1884

page_text: REGINALD NORTHALL LAURIE of Austin Friars in the City of London, Merchant
do hereby declare the nature of this Invention for "IMPROVED ANTI INDUCTION
SYSTEM FOR TELEGRAPH CABLES AND WIRES" and in what manner the same is to
be performed, to be particularly described and ascertained in and by the following
statement:-
My Invention relates to the use of parallel wires or cables for telegraphs,
telephones and the transmission of electric currents generally and has for its object
the prevention of induction in the lines and of disturbances due to atmospheric
electricity, the reduction of the static charge therein to a minimum and the
reduction to a minimum of resistance to the return current in the working circuits
without. the disadvantages attendant upon a ground connection.
My Invention consists in the combination with each other and with suitable
keys or commutators, and conductors, substantially in manner as is hereinafter
fully described or any desired number of parallel, insulated telegraph or telephone
wires, either bound together in a cable, or otherwise carried in the same direction
side by side, so that whilst each wire may serve independently as the conductor
for a direct electric current in the customary manner, all the remaining wires in
the system not at the moment transmitting a direct current shall serve conjointly.
and independently of any ground connection as conductors for the return current
either alone or in combination with an extra auxiliary wire reserved exclusively
for the return current.
My Invention consists likewise in the combination with suitable keys or
commutators and conductors and with a system of insulated telegraph or telephone
wires, either bound together in a cable or otherwise carried in the same direction
side by side and adapted and arranged to serve as conductors for direct currents of.
an auxiliary wire or cable reserved exclusively for the return current or currents
so that whilst each primary wire may serve independently as the conductors for a
direct electric current in the customary manner, the auxiliary wire or wires shall'
serve independently of any ground connection and either alone or conjointly' with¸
3

page_text: -
the remaining wires in the system not at the moment transmitting a direct current,
as the conducting medium for the return current.
In the accompanying Drawings
Figure 1 is a diagram illustrating the use and application of my improved
telegraphic keys and devices in combination with two independent telegraph lines
whereby either may be made to serve as a conductor for the return current from
the other independently of the ground.
Figure 2 is a similar diagram illustrating my Invention in connection with
two independent lines and a single separate return wire without ground connections
and.
Figure 3 illustrates the more comprehensive application of my Invention in
connection with a cable of many wires including an auxiliary return wire.
A. A. represent the telegraphic keys B. B. the batteries C. C. the sounders and
D. D the main wires in use upon the telegraph lines included in my improved
system.
The bar of each key A is connected with its line D and sounder C and its
anvil e is connected with one pole of the local battery B. An extra contact F is
provided at the back end of the key which, when the key is "up" and at rest
connects it constantly with a return wire R. This return wire R is connected
with the opposite pole of the battery of the instrument and with the return wire
and batteries of all other instruments at its end of the cable or system of parallel
lines, and becomes a substitute for the ordinary ground connections which are
entirely dispensed with. In the accompanying Drawings which illustrate the
working of lines thus connected the instruments at one end of the cable or system
of parallel lines are numbered 1. 3. 5. 7 9 and 11 and the instruments at the
opposite end are designated by the numbers 2. 4. 6. 8. 10 and 12.
When the keys are all "up" in the position which they automatically assume
when not in use (see the instruments 2. 3 and 4), a general return circuit is closed
over all the wires whilst the batteries B. B. are all cut out of circuit. If now the
key A of one of the instruments (see N° 1 or N° 7) is depressed the particular line
to which it is attached is thereby disconnected from the general return circuit
while as the key is brought into contact with the anvil to which a battery B is
connected the line circuit is closed and the current from the battery is transmitted
through the key to the line and over it to the sounder C of the opposite receiving
instrument (or 8). The return current from this sounder 2 will pass through the
key-bar 2 and through its back contact at F to the return wire R and over said
wire to the general circuit by which it will be transmitted back to the battery at
1 (or 7) as is indicated by the wavy arrows in the Drawings.
It will be seen by reference to said Drawings that the return current will pass
from the anvil F of the receiving instrument 2 through the return wire R and its
connections to the anvil F of each and every key which is "up" and in contact
with its anvil, and thence through the key bar and the accompanying sounder over
the line wire to the sounder and key of the instrument at the other end of the line,
and by means of the contact of that key with its anvil through the saine to the
return wire at that end of the line and so back to the battery of the transmitting
instrument N° 1 to complete its working circuit. The return current will thus be
conducted back through all the lines not cut out of the general return circuit by
the depression of the key bar in either of the instruments connected therewith
andhence the greater the number of lines thus connected in one general returni
system the less will be the resistance to the return current.
Although for the sake of illustration, two lines are illustrated in the diagram,
Figure 1, as thus connected, my Invention in this simple for is designed to be used
in connection with a comparatively large number of lines of which but few are
likely to be used at the same time so as to leave always a larger number of lines
open to the return current than of lines in use and thereby diminish the resistance.
Hence the greater the number of lines included in the system the greater its
Advantages.

page_text: Where but a small number of wires are included in the system or where a
number of the lines are liable to be brought simultaneously into use with direct
currents I combine therewith a large auxiliary return wire R which by preference
is placed in the center of the cable or system of parallel wires and connects the
same with the return wires R. R. of the several instruments at either end of the
lines, as shown in Figures 2 and 3-Where such a direct return wire is employed,
the return current is divided in its course between it and the remaining wires not
in use, as indicated by the wavy arrows in Figures 2 and 3 and the resistance to
the return current is correspondingly diminished, whilst the currents passing
through the instruments are also to the same extent weakened.
The use of the independent return wire is especially advisable in all telephone
systems, owing to the extreme sensitiveness of the telephone instruments to the
influence of even weak currents.
It is to be understood from all this that the independent central wire for the
return current may only be omitted with advantage in cables embracing a larger
number of direct wires over which no great amount of simultaneous business is
likely to occur as the moment a line is closed for a direct current it is cut out from
the general return circuit and temporarily lost for use as a return wire and the
resistance of the general return circuit is correspondingly increased-If in cables of
a small number of wires the return wire proves at any time insufficient (which
will appear by an action of the return current upon the instruments) either one of
the remaining wires may be temporarily joined thereto to double its capacity.
This however will very rarely occur especially when the cable is connected with
intermediate stations which operate to increase the resistance in the direct wires
without affecting the resistance in the special return wire the instruments beiug
connected with the direct wires whilst the return wire is not thus encumbered.
In my improved system as above described of connecting the conducting wires
included in a cable or in a series of parallel wires, with each other and with the
line instruments and batteries whereby the return current for each line is carried
back in close proximity to its direct wire, over one or more of their remaining
wires in the system the return current is made to neutralize the inductive influences
which would otherwise be exerted upon the neighbouring wires by the direct
current or currents running in one direction only and the disturbing effects of
induction which exist in cables and in proximate parallel telegraph and telephone
lines as ordinarily constructed are thereby avoided-Moreover as in this improved
anti-induction system the cable is made to contain in itself perfectly closed circuits
which run with balanced intensities and quantities in opposite directions and
without ground connections it is evident that no outside inductive influence,
however active can overcome its passivity or neutrality and the cable will be
wholly relieved from the disturbing influences ordinarily arising in the presence of
thunder storms or auroral displays or from earth currents whilst it offers at
the same time less resistance than any form of compensated cable heretofore
constructed.
The static charge in the lines which, as is well known is one of the most serious
drawbacks to a rapid transmission of telegraphic signals especially in underground
and submarine cables is greatly reduced in my system and in fact may be reduced
therein to a minimum by simply working one half of the direct wires with the
positive and the other half with the negative currents.
The transmission by my Invention of the return current through many wires
and especially in connection with a wire specially devoted to that purpose and
which may be made very large affords all the advantages to be found in a ground
connection without its advantages. By increasing the number of wires the
resistance of the return current in the cable may be reduced to the minimum of
the ground connection and in all cases my system comprising three or more wires,
will offer less resistance than will a double wire whether straight or twisted in
which the resistance of the return current is equal to that of the direct current.
and it will be found even more advantageous when compared with the so called

page_text: "solenoid" wires in which the resistance to the return current is increased many
fold.
I am aware that by means. of switches or commutators a return circuit has
heretofore been established for a direct current sent through any one of a series of
wires in a telephone system back through the remaining wires of the system
independently of the ground.
Having now particularly described and ascertained the nature of the said
Invention and in what manner the same is to be performed as communicated to
me by my foreign correspondent, I declare that what I claim is :-
First. The combination in an electric telegraph.or telephone system with two or
more main parallel conducting wires severally adapted for transmitting direct
electric currents of an auxiliary parallel wire and suitable commutators and
conductors adapted to establish from either main wire which may be transmitting
a direct current, a return circuit through said auxiliary wire independent of
any ground connection substantially in the manner and for the purpose herein
set forth.
Second. The combination in an electric telegraph or telephone system with two
or more main parallel conducting wires severally adapted for transmitting direct
electric currents of an auxiliary parallel wire and suitable commutators and
conductors adapted to establish from either main wire which may be transmitting
a direct current, a return circuit to battery conjointly through said auxiliary wire
and the main wires not otherwise in use independently of any ground connection,
substantially in the manner and for the purpose herein set forth.
Third. The combination with an electric telegraph cable or system of parallel
line wires, and with the sounders and batteries for each line in said cable or system
of telegraph keys each having its anvil connected electrically with one pole of its
appropriate battery and its bar connected in like manner directly with one end of
its appropriate line wire and each of which is fitted with a back contact adapted
to close; when the key is up and the connection with its battery thereby broken,
an electrical connection between its bar and the opposite pole of each and every
battery and the back contact of each and every other key at its end of the cable or
system, substantially in the manner and for the purpose herein set forth.
Dated this 3rd day of May 1884.