IMPROVEMENTS IN ELECTRICAL CONDUCTORS
Year: 1885

page_text: I CHARLES AUBREY DAY of 321 High Holborn in the County of Middlesex,
Fellow of the Institute of Patent Agents, do hereby declare the nature of the said
invention for "IMPROVEMENTS IN ELECTRICAL CONDUCTORS," & communication to
me from abroad by Henry French Campbell of Concord, State of New Hampshire,
United States of America, and in what inanner the same is to be performed, to be
particularly described and ascertained in and by the following statement:-
This invention having for its object to prevent disturbances arising from
induction or earth currents and also to obviate the effect of retardation which is
Bo detrimental to the operation of long cables is based on the discovery that shields
composed of para-magnetic or combined para-magnetic and dia-magnetic substances
are very effectual. in preventing induction between parallel wires, possessing this
property to a far greater degree than diamagnetic materials, such as copper, lead,
tin and others which have been heretofore ineffectually used in the attempt to
prevent or diminish inductive disturbances:
The present invention consists partly in connecting together at their ends the
anti-inductive shields of two independent cables.
The invention further consists in connecting the telephone or other instrument
in circuit between one of the independent wires of the cable and the anti-inductive
shield, composed mainly of para-magnetic material, of the said wire or cable, by
which arrangement the retardation and the disturbances arising from earth currents
become less than when the circuit is completed between the ends of the shield and
between the ends of the enclosed wire by the ground in the manner usually
practised.
The invention further consists in an insulated conductor provided with two
concentric anti-inductive shields composed mainly of para-magnetic material
insulated from one another and electrically connected together at the ends of the
cable so as to form a complete metallic circuit traversing the entire length of the
cable.
:
Fig 1 shows in diagram a number of circuits constructed and arranged in
accordance with this invention. A A¹ represents two cables having substantially
the same direction, or extending between the same terminal points, each cable

page_text: being composed of a group of insulated conductors as a, a¹, a³ etc, preferably each
provided with an anti-inductive shield b, composed of paramagnetic or combined
dia-magnetic and para-magnetic materials, such as iron or manganese or a mixture
of the two, either alone or in connection with a dia-magnetic material, such as tin
or zine which may be coated on the surface of the para-magnetic substances.
The said shield may be applied on the surface of the insulating covering of the
wire or conductor in any suitable or usual way, a tape or ribbon, or one or more
wires wound spirally on the said surface being found effective in practice.
The said conductors a, a¹ &c., upon leaving the cable, branch out to the different
minor stations, where they are connected with the telephones T, or other electrical
instruments to be placed in circuit, the other terminals of the said telephones or
instruments being connected, by wires 2, with the said anti-inductive shield b
which thus forms the return portion of the circuit, which is itself, not necessarily
connected with the ground at any point.
The cables A, A¹ have the shield portions b electrically connected together at the
ends of the cables by wires 3, thus forming a complete circuit through the said
shields.
The term "cable," in this specification, is intended to include any conductor or
group of conductors, and the shield or covering b may.consist of a pipe or a wrapping
of wire or ribbon or other covering outside of the insulation of each individual
conductor or outside of the entire group of conductors which may or may not each
be provided with an anti-inductive shield, the said covering being composed of the
para-magnetic or combined para-magnetic and dia-magnetic materials, para-
magnetic being generally in predominance when both are used.
The connection of the shields or outer metallic coverings of two or more cables
is especially advantageous when the said cables are buried beneath the surface of
the ground or are laid under water, and in order to insure the best results, the
said covering in the two cables as well as the connecting wires 3 between their
adjacent terminals should be of about equal capacity, and the shields connected
together at a point beyond the submerged or buried portion.
By the connection together in circuit with one another of the shields or coverings
of two cables, the currents which pass along the outer covering of either cable and
would without such connection be discharged at the ends of the cable upon the
enclosed conductor or conductors will be conveyed to the other shield and their
disturbing influence thus removed from the enclosed wires and instruments included
in circuit therewith..
In the case of a sub-marine or other cable, when there is no neighboring shielded
cable to complete a shield circuit, the construction shown in figures 2 and 3 may
be adopted, the wire a¹ being suitably insulated as usual and provided with an
anti-inductive shield or covering b over the said insulation, which covering is
surrounded by insulating material and enclosed in a secondary or outer. anti-
inductive covering b¹ the two coverings b, b¹ being electrically connected at their
ends by wires 30 to make a complete shield circuit.
The circuit for the enclosed wire a¹0 is completed by wires 20, and the shields b, b¹,
and the evils arising from a grounded circuit or one composed partly of the earth,
are wholly avoided.
In some instances where the cable consists of a number of conductors (either
each independently shielded or not) enclosed in a pipe B of iron or steel or other
materials having the properties requisite for an anti-induction shield as shown in
fig: 4, it may be desirable to complete the ĉircuit for the shield by a special wire r
instead of by the shield of another cable.
. No broad claim is made to a conductor having an insulated covering, and
another tubular conductor at the outside thereof, employed to complete the circuit
for the enclosed conductor, as such conductors have been previously employed,
but previous to the present invention the outer conductor has been composed
of tin, lead, or copper, that is solely of dia-magnetic material, and the present
invention consists in the employment of an outer conductor composed mainly of

page_text: para-magnetic material, which has been proved by actual test, to give far better
results in suppressing inductive disturbances and diminishing the retardation
which is found to prevent telephonic communication over long distances by the
conductors heretofore employed.
-
"Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, I declare that what
is claimed is "
1. The combination of two or more separate cables, each having outside of the
insulating material of its enclosed conductor or conductors, a shield or covering of
para-magnetic or combined para-magnetic and dia-magnetic materials, with
conductors connecting the shields or coverings together, substantially as and for the
purpose specified.
2. An electrical conductor, insulated and provided with a shield or covering of
para-magnetic or combined para-magnetic and dia-magnetic substances, combined
with a telephone or other electrical instrument connected in circuit between the
said conductor and shield, substantially as described.
3. An electrical cable composed of an insulated wire having upon it two
anti-inductive shields composed of para-magnetic or combined para-magnetic
and dia-magnetic materials insulated from one another except at the ends of the
cable where they are connected to constitute a metallic circuit extending the entire
length of the cable, substantially as described.
4. An electric cable having an anti-inductive outer covering composed of
para-magnetic or combined para-magnetic and dia-magnetic materials, combined
with a wire 7, connecting the ends of the said covering, substantially as described.
Dated this 28th day of October 1884.
DAY, DAVIES & HUNT,
321, High Holborn, London, W.C.,
Agents for the Applicant.
DAY, DAVIES & HUNT,
321, High Holborn, London, W.C.,
Agents for the Applicant.