IMPROVEMENTS IN THE INSULATION OF ELECTRIC CONDUCTORS ESPECIALLY APPLICABLE TO THE MANUFACTURE OF COMPOUND CONDUCTORS FOR TELEPHONIC AND OTHER PURPOSES
Year: 1884

page_text: I, ARTHUR WILLIAM LOVELL REDDIE of the Office for Patents, 6 Bream's
Buildings, Chancery Lane in the County of Middlesex, Patent Agent, do hereby
declare the nature of my invention for IMPROVEMENTS IN THE INSULATION
OF ELECTRIC CONDUCTORS ESPECIALLY APPLICABLE TO THE MANUFACTURE OF
COMPOUND CONDUCTORS FOR TELEPHONIC AND OTHER PURPOSES, and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :-
For insulating electric conductors or wires it is desirable that the covering of
insulating material should be as thin as is consistent with a perfect insulation, and
this is particularly true of wire which is to be wound to form electro magnets for
electric lighting and other purposes where it is desirable that the magnet shall be
of small size as compared with the required strength.
This invention is based on the discovery that thin Manilla or other pure
vegetable paper possesses in a high degree the qualities for an insulating material,
and that by its use it is possible to obtain a more nearly perfect insulation with a
less thickness of covering than has heretofore been possible.
The improvements consist in an electric wire having a covering consisting of a
spirally wound and lapping strip or strips of paper, composed of pure vegetable
fibre and applied in its unchanged fibrous condition to the wire, the paper forming
of itself, the insulating covering for the wire.
The improvements also consist in an electric wire having a covering consisting
of a spirally wound and lapping strip or strips of paper, applied with a waterproof
adhesive substance consisting of a thin solution of india rubber, the paper formning
of itself, the insulating covering for the wire.
A further object of the improvements is to provide a compound conductor, that
is a conductor comprising a primary conductor or wire and an induced current or
secondary conductor or wire, whereby induced currents may be more effectively
controlled than heretofore and the primary wire relieved of induction to a greater
degree than has heretofore been possible.
To this end the improvements further consist in a compound conductor com-
prising a primary conductor externally insulated, a spiral induction or secondary
:

page_text: conductor and a covering for the induction or secondary conductor consisting of
a spirally wound and lapping strip or strips of pure vegetable paper, forming of
itself an insulating covering for the induction or secondary conductor.
The improvements also consist in a compound electric conductor comprising a
primary conductor, an insulation therefor composed of a spirally wound and
lapping strip or strips of pure vegetable paper, a spirally wound induction or
secondary conductor external to said insulation, and a spirally wound strip or
strips of pure vegetable paper applied outside the induction or secondary conductor,
the paper forming of itself insulating coverings for the primary and secondary
conductors.
In the accompanying Drawing Fig. 1 represents a piece of wire having an
insulation which consists of a single spirally wound strip of paper lapped upon
itself and thereby forming an insulation of two thicknesses of paper throughout;
Fig. 2 represents a wire having an insulation composed of two spirally wound and
lapping strips of paper, laid one over the other to break joints; Fig. 3 represents a
compound conductor embodying the improvement and an outline drawing of two
telephone instruments connected thereby; and Fig. 4 is a view illustrating more
clearly the construction of the compound conductor.
Similar letters of reference designate corresponding parts in all the figures, and
in all, the thicknesses of the paper coverings is exaggerated, to illustrate that
feature more clearly.
Referring first to Figs. 1 and 2, A designates the wire which may be copper or
iron and B designates the strips of paper which form the insulation.
The paper which it is preferred to use is very thin and tough Manilla paper
cut into strips of about three fourths, 3/4, of an inch more or less, in width, but the
paper may be made of any pure vegetable fibre, and is applied to the wire in its
unchanged fibrous condition."
The adhesive substance which it is preferred to use is a thin solution of india
rubber in any of its well known solvents, this constituting a perfectly waterproof
substance. In any case the adhesive substance is as thin as possible so that the
paper will not be separated materially from the wire, or the layers of paper from
each other. It is not designed that the adhesive substance shall constitute an
insulation for the wire, but the paper of itself, forms the insulating covering.
In laying on the strip or strips of paper the thin waterproof adhesive material is
preferably applied by a brush or other means to the inner side of the strip and will
then adhere to the wire and to the portion of the strip which is overlapped in
winding spirally. When the waterproof adhesive substance is applied to the inner
side of the strip the outside of the insulation is not sticky during the process of
manufacture.
In Fig. 1 the single strip which constitutes the insulation is wound spirally and
lapped about half its width thus producing an insulation consisting of two
thicknesses of paper.
In Fig. 2 the insulation consists of two strips wound one over the other with a
lap of about half the width, the second strip being laid so as to break joints with
the first, thus giving an insulation of four thicknesses of paper.
After the winding of the paper is completed the insulating covering of paper
may or may not have paraffin or other waterproofing material applied to the
exterior.
'
The strips of paper to preserve them may be saturated with paraffin before
winding. The paraffin may be applied to the strips of paper by immersing the
bobbins on which the strips are wound in a bath of paraffin.
An insulation of paper is very desirable because it will not soon rot underground;
and because, by using paper composed of pure vegetable fibre, a more nearly perfect
insulation can be produced with a less thickness of covering than can be obtained
in any other way. A single strip of paper, giving two thicknesses throughout, will
add only about four one-thousandths of an inch to the size of the wire.

page_text: A waterproof adhesive substance consisting of a thin solution of india rubber is
also desirable because by its use a certain amount of elasticity between the
superposed layers of paper and between the paper and wire is obtained and hence
the insulating covering of paper will not crack or break when the wire is bent.
Referring now to Fig. 4 A designates the primary conductor which may be of
copper or iron wire and of any desired gauge.
The insulation of this primary conductor is effected by winding it spirally with
pure vegetable paper, very thin and tough, and cut into strips of about three-
fourths of an inch in width, more or less, the paper being lapped on itself in
winding.
In winding the spiral strip a suitable adhesive substance is applied to the inner
side of each strip as above described, whereby it is caused to adhere to the wire
and the lapping layers of paper.
The primary wire is here represented as having two spirally wound strips of
paper B B¹ in the process of being applied thereto.
Outside the thus insulated primary wire A, is wound a spiral band or strip B³,
of the same kind of paper as the strips B B', and beneath the strip B is laid
spirally a conductor A*, which may consist of a fine wire or a thin metallic band or
ribbon. After the strip B2 with the underlying induction conductor A*, has been
laid on, one or more strips of paper B³ B* similar to the strips described are wound
spirally on, outside the induction conductor A*, and secured by an suitable adhesive
substance.
C, C, Fig. 3, designate the two instruments connected by the primary
conductor A.
The two ends of the primary conductor A are fastened in binding posts c, of the
two instruments C, C, which may be presumed to be telephones, and the current
after passing through each instrument at one or other end thereof passes through a
binding post c', and thence through a conductor c to the ground c³. In one of the
conductors, c², is a battery c*.
The two ends of the induction conductor A*, are connected close to and inside
the instruments with binding posts d and then by wires d' with the ground d².
Now from the above description it will be clearly understood that the induction
conductor Ahas no connection with the ground at frequent points between tho
ends but is only grounded just within or inside of the instruments C, C, and
therefore the length of induction conductor is much greater than the length of the
primary conductor (as much as one-half greater in some cases).
This increased length of induction conductor offers no material obstacle to the
induced current, but it does offer a very material obstacle to any escape of the
primary current through said induction conductor and none of the primary current
can therefore be lost, even though the wire be greatly overcharged with electricity.
Inasmuch as the points for grounding the ends of the induction conductors A*
are just inside or within the instruments C C, the induced current will not pass
through the instruments but will be grounded and thus got rid of.
The improvement above described renders it possible to produce a properly
insulated compound conductor, which will be no larger in size than a simple
conductor of the same size as the primary conductor of the compound conductor
and insulated by any of the methods heretofore used.
It is not desired to include in this improvement a wire having a strip or strips
of asbestos or parchment paper wound spirally upon it, nor a wire having an
insulation composed of bituinen or other compound secured or confined by a
wrapper or envelope consisting of spirally wound strips of paper, but
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is
1. An electric wire having a covering consisting of a spirally wound and lapping
strip or strips of paper composed of pure vegetable fibre and applied in its

page_text: unchanged fibrous condition to the wire, the paper forming of itself, the insulating
covering for the wire, substantially as herein described.
2. An electric wire having a covering consisting of a spirally wound and lapping
strip or strips of paper applied with a waterproof adhesive substance consisting of a
thin solution of india rubber, the paper forming of itself, the insulating covering
for the wire, substantially as herein described.
3. The compound electric conductor consisting of a primary conductor externally
insulated, a spiral induction or secondary conductor, and a covering for said
induction or secondary conductor consisting of a spirally wound and lapping strip
or strips of pure vegetable paper forming, of itself, an insulating covering for the
induction or secondary conductor substantially as and for the purpose herein
described.
4. The compound electric conductor consisting of a primary conductor, an
insulation therefor composed of a spirally wound and lapping strip or strips of pure
vegetable paper, a spirally wound induction or secondary conductor external to the
said insulation, and a spirally wound strip or strips of pure vegetable paper applied
outside said induction or secondary conductor, the paper forming, of itself,
insulating coverings for the primary and secondary conductors, substantially as
and for the purpose herein described.