IMPROVEMENTS IN ELECTRICAL CONDUCTORS
Year: 1883

page_text: LETTERS PATENT to Raphael Hunter Brandon, of 1 Rue Laffitte, Paris, in
the Republic of France, Engineer and Patent Agent for an Invention of
IMPROVEMENTS IN ELECTRICAL CONDUCTORS communicated to him by Henry
French Campbell, of Concord, State of New Hampshire United States of
America.
PROVISIONAL SPECIFICATION left by the said Raphael Hunter Brandon at
the Office of the Commissioners of Patents on the 27th December 1883.
RAPHAEL HUNTER BRANDON, of 1, Rue Laffitte, Paris, in the Republic of France,
Engineer and Patent Agent "IMPROVEMENTS IN ELECTRICAL CONDUCTORS
communication to me by Henry French Campbell, of Concord, State of New
Hampshire, United States of America)
"
(A
This Invention has for its object to prevent disturbance arising from induction in
electrical conductors.
Electric cables have been made in which each independent conductor covered
with the usual insulating material is provided with an outer metallic covering
usually composed of a lead or copper tube, or of a covering of tin foil, it having
been supposed that such a covering would prevent the transmission of disturbing
currents to the wire.
Experiment however has shown that such coverings are ineffectual, at least for
cutting off such currents as will produce disturbances in the telephonic instruments
of the present day.
Long investigation has demonstrated that while an ordinary covering composed
of the metals usually employed for this purpose, viz, copper, lead, or tin, all good
conductors of electricity, are inefficient, there are certain substances which when
employed as a covering or shield for an insulated wire will greatly diminish or
entirely annul the disturbances referred to, and the present Invention is based on
this fact.
There exist in nature two classes of substances or elements distinguished by
certain electrical phenomena and known as diamagnetic and paramagnetic.

page_text: An effectual shield against the effects of induction may be produced by the
employment of these two classes of elements in conjunction, and especially in
certain proper proportions and arrangements hereinafter described.
A shield composed of essentially pure paramagnetic and diamagnetic elements in
which the former predominates produces a very effectual shield against induced
currents, the quantity of the combined elements and their thickness depending
upon the strength of the induced current to be overcome.
There are other materials besides such a combination of paramagnetic and
diamagnetic substances which can be employed and will give far better results than
the materials formerly used.
Extended investigations have shown that while the materials known and classed
as diamagnetic materials including copper, lead, and tin, which have been most
commonly used on account of their abundance, their electrical conductivity, and
the ease with which they may be manipulated, are ineffectual, all the paramagnetic
elements are found to be effective in a very high degree.
This Invention consists in the hereinafter described means for suppressing
inductive disturbances in electrical conductors.
Also in an electrical conductor provided with a covering of insulating material
and having an enclosing anti-inductive shield or envelope composed of paramagnetic
and diamagnetic substances upon the said covering or of one or more paramagnetic
substances, the said shield forming a portion of a complete electric circuit
independent of the enclosed conductor.
Also in the combination with an electrical conductor having an anti-inductive
shield, of terminals reflexed or bent back.
Also in an electrical conductor having a flexible insulating covering, combined
with an anti-inductive shield composed of a strip or band of paramagnetic and
diamagnetic substances, or of one or more paramagnetic substances wrapped
spirally around the said insulating covering.
Also in a series of independent insulated conductors forming a cable, each
insulated conductor provided with an anti-inductive shield as described, the said
shield forming a portion of a metallic circuit in the cable, independent of the said
conductors enclosed in the shields.
Iron, nickel, cobalt, manganese, platinum, and osmium, may be mentioned as the
best among the class of paramagnetic substances, and bismuth, antimony, zinc,
cadinium, sodium, mercury, lead, silver, copper, sulphuric muriatic and nitric acids,
and sulphur in its various combinations may be mentioned as among the best of
the diamagnetic substances; and various methods of conjoining one or mord
elements of the one class with one or more elements of the other class will readily
suggest themselves to those familiar with chemical and metallurgical operations.
When metal substances are chosen one or more from each class, they have
been found to produce excellent results when applied in any of the following
methods, namely, as a tube or envelope of the distinctive metals one surrounding
the other and both applied as continuous unbroken coverings upon the outsides of
any usual insulating covering of the wire or conductor to be protected.
One or more metals of the one class may be deposited upon the surface of an
envelope or tube composed of one or more metals of the other class, by any
suitable chemical or other process, as for example, by electroplating a diamagnetic
element such as bismuth, antimony, or copper, upon a paramagnetic element such
as iron, or manganese, or a combination thereof, outside of an insulating covering,
thus forming a shield or envelope.
The thickness of the shield may be proportioned to the work to be done, or in
other words to the strength of the electric currents from which protection is
desired.
In some instances the shield or envelope may be applied in the form of a paint
or flux composed of some suitable vehicle containing elements of the two classes in
the proper proportions in a finely divided or pulverized state, or the diamagnetic

page_text: elements in the form of powder may be applied to a paramagnetic shield or
envelope, but a continuous metallic covering produces better results.
An anti-inductive shield or envelope embodying this Invention, and one which
is readily available both on account of the abundance and cheapness of the
materials and their adaptability because of their mechanical properties to the use
in question consists of sheet iron coated with tin or copper or both by the
ordinary processes of dipping or with zinc by the usual process of galvanizing.
A ribbon of iron of from 18 to 20 gauge, coated by dipping, is generally sufficient
for ordinary telephonic purposes, but when several wires are to be used in a cable,
as each wire has its own covering so that two coverings or shields are interposed
between each two wires, a thinner shield may be employed.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Raphael Hunter Brandon in the Patent Office on the 21st May 1884.
RAPHAEL HUNTER BRANDON of 1 Rue Laffitte, Paris, in the Republic of France,
Engineer and Patent Agent 'IMPROVEMENTS IN ELECTRICAL CONDUCTORS" a
communication to me by Henry French Campbell of Concord, State of New
Hampshire, United States of America.
This invention has for its object to prevent disturbance arising from induction in
electrical conductors.
Electric cables have been made, in which each independent conductor covered
with the usual insulating material, is provided with an outer metallic covering
usually composed of a lead or copper tube, or of a covering of tin foil, it having
been supposed that such a covering would prevent the transmission of disturbing
currents to the wire.
Experiment, however, has shown that such coverings are ineffectual, at least for
cutting off such currents, as will produce disturbances in the telephonic instruments
of the present day.
Long investigation has demonstrated, that while an ordinary covering, composed
of the metals usually employed for this purpose, viz, copper, lead, or tin, all good
conductors of electricity, are inefficient, there are certain substances, which when
employed as a covering or shield for an insulated wire, will greatly diminish or
entirely annul the disturbances referred to, and the present invention is based on
this fact.
There exist in nature two classes of substances or elements, distinguished by
certain electrical phenomena and known as diamagnetic and paramagnetic.
An effectual shield against the effects of induction, may be produced by the
employment of these two classes of elements, in conjunction, and especially in
certain proper proportions and arrangements, hereinafter described.
A shield composed of essentially pure paramagnetic and diamagnetic elements,
in which the former predominates, produces a very effectual shield against induced
currents, the quantity of the combined elements and their thickness depending
upon the strength of the induced current to be overcome.
There are other materials besides such a combination of paramagnetic and
diamagnetic substances, as will be hereinafter described and claimed; which can be
employed and will give far better results than the materials formerly used.
Extended investigations have shown, that while the materials known and classed
as diamagnetic materials, including copper, lead and tin, which have been most
commonly used on account of their abundance, their electrical conductivity, and
the ease with which they may be manipulated, are ineffectual, all the paramagnetic
elements are found to be effective in a very high degree.
The invention consists in the hereinafter described means for suppressing inductive
disturbances in electrical conductors.
Also in an electrical conductor provided with a covering of insulating material
and having an enclosing anti-inductive shield or envelope, composed of paramag-
netic and diamagnetic substances, upon the said covering, or of one or more
paramagnetic substances, the said shield forming a portion of a complete electric
circuit, independent of the enclosed conductor.
Also in the combination, with an electrical conductor, having an anti-inductive
shield, of terminals reflexed or bent back.
Also in an electrical conductor, having a flexible insulating covering, combined
with an anti-inductive shield composed of a strip or band of paramagnetic and

page_text: diamagnetic substances, or of one or more paramagnetic substances, wrapped
spirally around the said insulating covering.
Also in a series of independent insulated conductors forming a cable, each
insulated conductor provided with an anti-inductive shield as described, the said
shield forming a portion of a metallic circuit in the cable, independent of the said
conductors enclosed in the shields.
Iron, nickel, cobalt, manganese, platinum and osmium, may be mentioned as the
best among the class of paramagnetic substances; and bismuth, antimony, zinc,
cadmium, sodium, mercury, lead, silver, copper, sulphuric, muriatic, and nitric acids,
and sulphur in its various combinations, may be mentioned as among the best of
the diamagnetic substances; and various methods of conjoining one or more
elements of the one class, with one or more elements of the other class, will
readily suggest themselves to those, familiar with chemical and metallurgical
operations.
When metallic substances are chosen, one or more from each class, they have
been found to produce excellent results, when applied in any of the following
methods, namely, as a tube or envelope of the distinctive metals, one surrounding
the other, and both applied as continuous unbroken coverings upon the out-sides of
any usual insulating covering of the wire or conductor to be protected.
One or more metals of the one class may be deposited upon the surface of an
envelope or tube, composed of one or more metals of the other class, by chemical
or other process, as for example, by electroplating a diamagnetic element, such as
bismuth, antimony or copper, upon a paramagnetic element such as iron or manganese
or a combination thereof, outside of an insulating covering, thus forming a shield
or envelope.
The thickness of the shield may be proportioned to the work to be done, or in
other words to the strength of the electric currents from which protection is
desired.
In some instances, the shield or envelope may be applied in the form of a paint
or flux composed of some suitable vehicle containing elements of the two classes in
the proper proportions, in a finely divided state or pulverized, or the diamagnetic
elements, in form of powder, may be applied to a paramagnetic shield or envelope,
but a continuous metallic covering, produces better results.
An anti-inductive shield or envelope, embodying this invention, and one which
is readily available, both on account of the abundance and cheapness of the materials
and their adaptability, because of their mechanical properties to the use in question,
consists of sheet iron, coated with tin, or copper, or both by the ordinary processes
of dipping, or with zinc by the usual process of galvanizing.
A ribbon of iron of from 18 to 20 gage, coated by dipping, is generally sufficient
for ordinary telephonic purposes, but when several wires are to be used in a cable,
as each wire has its own covering, so that two coverings or shields are interposed
between each two wires, a thinner shield may be employed.
Figure 1 is a side elevation, partly in longitudinal section of a cable composed
of electric conductors provided with anti-inductive shields, embodying this
invention.
Figure 2, a transverse section thereof.
Figures 3 and 4, similar views of a modified form of cable, and figures 5 and 6,
modifications to be referred to.
The cable is composed of a series of independent wires or conductors a, each
provided with an insulating covering b, and each being intended to form a portion
of an independent electric circuit containing telephonic or other electrical
instruments.
The insulating material b, may consist of cotton, rubber, parafine, or substances
generally known and classed as dielectics or insulators, and they should be
sufficiently flexible to admit of the conductor being wound upon a reel and bent.
The said insulating covering of each wire is provided with a shield or envelope c,

page_text: composed of paramagnetic and diamagnetic material, as hereinbefore described, or of
a ribbon of one or more annealed paramagnetic materials.
As shown in figure 1, the envelope c is made either from a strip or ribbon of the
proper materials such as iron coated or plated with tin, zinc, or copper or any one
or more diamagnetic metals, or of one or more annealed paramagnetic substances,
the said ribbon being preferably wound spirally around the insulated wire or
conductor, care being taken that each successive turn of the spiral overlaps the one
already laid upon the wire, or comes in contact, spiral with spiral, so that no space
is left between the successive turns when in position for use. A shield constructed
in this manner is very flexible, and a conductor provided with it may be bent
almost as easily as the ordinary insulated conductors having no external metallic
covering.
As shown in figure 5, the shield consists of continuous concentric tubes of the
distinctive elements or substances, this construction affording somewhat less
flexibility than that illustrated in figure 1, but the protected conductor still being
sufficiently flexible for most purposes.
When the shield is in the form of a continuous tube, as illustrated in figure 5,
and it is desired to bend the conductor at a sharp angle, the shield may be made at
the corner or bend of a spiral ribbon, as shown in figure 1, the ends of the
ribbon being soldered to the tubular portion of the shield at either side of the
angles.
Figure 6, is intended to illustrate a shield composed of the elements in a
pulverized condition, applied to the insulating covering, by means of a suitable
flux or fluid vehicle after the manner of a paint.
The shield c should form part of a complete electrical circuit independent of the
enclosed conductor, it being shown in figure 1, as having its ends in electrical
connection with the ground and the terminals or ground connections of the said
shield should themselves be protected from the main wire a by the anti-inductive
shield.
To effect this, the terminal wire d connecting the shield c of the main wire a
with the ground, may itself be provided with a shield c¹ of the same nature as that
of the main wire a, and in order to more effectually exclude the possibility of the
current passing from the terminal wire d to the unprotected portion of the wire a
beyond the end of the shield e, the said terminal wire may be turned backward
along the trend of the main wire as shown at 2 figure 1, in which case the shield c¹
may if desired be omitted.
The wire a is adapted to have telephonic or other instruments connected with
its ends, and if desired to connect an instrument at an intermediate point or points,
suitable branch wires e may be connected directly with the wire a, as shown in
figure 1, care being taken that the said branch wire is properly insulated from the
shield c at the point where it passes through the said shield. The branch wire ⚫
should be insulated and provided with an anti-inductive shield c³, which should be
either connected with the ground or with the main portion c of the shield as by
the wire k.
The paramagnetic elements being stronger, should have relatively a thicker body
in the shield than the diamagnetic elements, the proportions of the two elements
depending upon the materials used, as for instance a smaller amount of zinc is
required, than of tin or lead.
The diamagnetic and paramagnetic classes include a large number of substances
widely varying in their electrical conductivity, some being generally classed as
insulators and others as conductors, and experiments have shown that the best
results are produced by using a shield, the paramagnetic and diamagnetic elements
of which are both good conductors.
Although experiments have shown that a shield composed of both paramagnetic
and diamagnetic substances, is the most effective, it is also true that a shield composed
of one or more paramagnetic substances is much more effectual than the shields,

page_text: composed of diamagnetic material, such as tin, copper or lead, which have been
used previous to this invention, and the shield, may, without departing from the
present invention be composed wholly of a paramagnetic material, either a single
substance, such as iron, manganese, cobalt, nickel, or a composition of two or more
of the said substances.
Iron is considered the best paramagnetic, when used alone or as the chief
element in quantity, when two substances are used, as it stands at the head of the
list of materials classed as paramagnetics.
The covering c, when wholly paramagnetic, can be most conveniently made of a
strip of iron annealed, or of a soft and flexible nature, wound spirally upon the
outside of the insulating material b, care being taken that each successive turn of
the strip is in close contact with, or partially overlaps the edge of the one already
applied, so as to form a complete uninterrupted covering. When the shields c of
the different wires a, are to form a part of a complete electric circuit, they may be
insulated from one another, as shown in figures 3 and 4, or if desired, may be in
electrical contact with one another as shown in figures 1 and 2.
In the former case, each individual wire will be connected by a terminal d, as
before described, with the ground or other return circuit, for conveying the currents
away from the said shields, thus preventing them from passing upon or affecting
the wires a enclosed within them.
When the shields are in contact with one another, as shown in figures 1 and 2,
they constitute practically a single conductor, and single terminals t of a similar
nature to the one d, previously described, may be employed at each end of the
cable, to connect the said shields with the ground, or with a metallic conductor
forming the return circuit for the said shields, as will be hereinafter described, the
said terminal t being shown in figure 1, as passing wholly around the cable, so as
to be in intimate contact with as many as possible of the shields.
The employment of an annealed strip, or ribbon of steel, or of homogeneous iron
or steel without fibre, or in fact any annealed or soft ribbon, composed of iron as
the base, is considered within this invention.
In the construction shown in figures 3 and 4, a portion of the shields care
insulated from the remainder as by coverings h; or if desired, each shield may be
insulated from its neighbours, and the shields that are insulated from one another
in the body of the cable, are connected together at the ends thereof, by a
conductor i of electricity, thus forming a complete metallic circuit within the cable
and independent of the wires a, which is an important feature of this invention.
By this arrangement, a current generated in the shield of any one of the wires a,
will pass throughout the circuit composed of the said shield, the connecting wires i
and other connected shield or shields, with little tendency to escape to the wires a,
enclosed in either of the said shields.
If desired, all the shields composing one part of the shield circuit, may be in
contact with one another, or an independent conductor may be employed to form
the return circuit for all the shields.
As a means of connecting the shields at the ends of the cable, they may be
extended beyond the insulating material h, surrounding them, as shown at 3
figure 3. and then brought into contact with one another
electrical conductors.
2. An electrical conductor provided with a covering of insulating material and
having an enclosing anti-inductive shield or envelope composed of paramagnetic
and diamagnetic substances upon the said covering, or of one or more paramagnetic
materials, the said shield forming a portion of a complete electric circnit, independent
of the enclosed conductor, substantially as described.

page_text: 3. The combination with an electrical conductor having an anti-inductive shield,
of terminals reflexed or bent back, as set forth.
4. An electrical conductor, having a flexible insulating covering, combined with
an anti-inductive shield composed of a strip or band of paramagnetic and
diamagnetic substances, or of one or more paramagnetic substances, wrapped
spirally around the said insulating covering, substantially as described.
5. In a cable, a series of independent insulated conductors, each provided with
an anti-inductive shield as described, the said shield forming a portion of a metallic
circuit in the cable, independent of the said conductors enclosed in the shields,
substantially as described.
In Witness whereof, I the said Raphael Hunter Brandon have hereunto set my
hand and seal this 20th day of May in the year of our Lord 1884
Witnesses:
P. SCHOLTUS
HORACE BRANDON
R. H. BRANDON
L.S.)