An Improvement in Electrical Conductors.
Year: 1895

page_text: Date of Application, 23rd Feb., 1895-Accepted, 7th Sept., 1895
[Communicated from abroad by THE ELECTRIC BELL AND RESISTANCE Co.,
of 46 Lawrence Street, Newark, New Jersey, U.S.A., Manufacturers.]
An Improvement in Electrical Conductors.
I, HUGH DONALD FITZPATRICK of 70 Wellington Street, Glasgow, Registered
Patent Agent, 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 preparation of a flexible insulated non-
metallic conductor and will be fully understood by referring to the accompanying
drawing taken in connection with the following Specification and claims,
Figure 1 being an elevational view of a flexible non-metallic conductor such as
carbon with a metallic conducting tip secured thereto, the latter being shown in
section.
Fig. 2 is an elevational view of the conductor shown in Fig. 1 with an insulating
coating braided thereon.
Fig. 3 is a similar elevational view with a different form of insulating coating.
Fig. 4 is a side elevational view of an electro-magnet wound with our improved
flexible insulated non-metallic conductor.
It is well known in the electrical art that carbon as an electrical conductor
possesses many qualities of usefulness not found in metallic electrical conductors,
such for instance as great specific resistance, decrease in conductivity for an
increase in temperature, little power of self-induction and the like; but no one, so
far as I am aware, has heretofore devised a carbon conductor which shall be
flexible and surrounded with an insulating coating, the flexibility being of such a
nature as to render it capable of use in positions where well known forms of insulated
metallic conductors are used, and hence adapting it for utilizing, at all times, all
of the above named qualities. It is the especial object of the present invention to
produce such a conductor. A common cord C of cotton or equivalent carbonizable
material is, therefore, subjected to carbonization while in its extended position or
while wound about a uon-combustible former of sufficient diameter to leave the
individual fibres of the cord substantially in their original positions. This cord is
carbonized in any well known manner to such an extent that when carbonized it
will not of itself sustain combustion. The cord is then surrounded by a coating of
insulating material of braided cotton thread B so adjusting the braiding machine or
so braiding the material that all strains put upon the cord lengthwise will be taken
up by the braiding. Such processes of braiding are well understood in the art of
insulating with braiding machines.
The carbon cord C may be surrounded with a winding or coating in the nature
of a ribbon of any well known kind of flexible insulating material, or may be
coated with rubber R as shown in Fig. 3. After the cord is thus prepared and
insulated, metallic tips L are electro-plated upon its ends. A conducting cord or
carbon when thus constructed is sufficiently flexible to be wound upon a spool so as
to construct an electro-magnet M as shown in Fig. 4. Such a conductor has many
uses in the art but particularly in rheostats, electrical measuring instruments, and
in all places where electrical conductors of high resistance are required, the nature
of such a conductor rendering it readily adaptable for use in compact form in a
small space.

page_text: I do not limit myself to any special form of insulation. I believe I am the first to
construct a flexible non-metallic conductor covered with an insulating coating and
I wish it understood that my claims shall include broadly any flexible insulated
conductor made of carbon or carbonizable material and adapted for use generally
in the electric art.
I am aware that it is old in the art to utilize water contained in a rubber or
equivalent insulating tube as a conductor and also that flexible electrical conductors
have heretofore been constructed of asbestos fibre coated with a conducting material.
I make no claim hereinafter broad enough to include such structures, as my claims
are directed to flexible conductors made of carbon or carbonizable material and
wholly surrounded by a coating of insulating material. I am also aware that it is
old in the art to electro-plate the ends of the carbon filaments used in incandescent
electric lamps for connection to the leading-in wires, and I make no claim broad
enough to include this feature, my claims being directed to flexible non-metallic
conductors which are surrounded or covered with flexible coatings in order that
conductors of this nature may be used where insulated conductors are ordinarily
used in the electrical art.
It will be obvious that, in place of the metallic tips L shown and described
herein, a suitable conducting cement may be employed similar to those commonly
applied to the ends of carbon filaments of incandescent electric lamps for the
connection of the leading-in wires.
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. A flexible conductor made of carbon or carbonizable material surrounded with
a flexible coating of insulating material.
2. A flexible conductor made of carbon or carbonizable material surrounded with
a flexible coating of insulating material and having metallic tips electro plated or
not secured to its ends.
3. A flexible conductor made of carbon or carbonizable material surrounded
throughout its length with insulating material and wound about the core of an
electro-magnet.
4. A flexible conductor made of carbon or carbonizable material surrounded
throughout its length with a coating of insulating material and wound in spiral
form upon a spool, bobbin or support, substantially as shown.
Dated this 21st day of February 1895.
H. D. FITZPATRICK.