IMPROVEMENTS IN INSULATING ELECTRICAL CONDUCTORS
Year: 1880

page_text: LETTERS PATENT_Elijah Marshall Allen, of Botolph Lane, in the City of
London, for an Invention of "IMPROVEMENTS IN INSULATING ELECTRICAL
CONDUCTORS." A communication from abroad by Adolphus A. Knudson and
Frederick L. Kanc, both of Brooklyn, in the County of Kings, and State of
New York, United States of America.
PROVISIONAL SPECIFICATION left by the said Elijah Marshall Allen at the
Office of the Commissioners of Patents on the 30th March 1880.
ELIJAH MARSHALL ALLEN, of Botolph Lane, in the City of London.
" IMPROVE-
MENTS IN INSULATING ELECTRICAL CONDUCTORS." [A communication from abroad
by Adolphus A. Knudson and Frederick L. Kane, both of Brooklyn, in the County
of Kings, and State of New York, United States of America.]
This Invention relates to an insulating coating for enveloping and protecting
electrical conductors, more especially such conductors as are designed for tele-
graphic purposes, and are therefore required in some instances to be suspended in
the air, and in other cases to be buried in the earth or submerged in water.
The Invention consists in applying to the conductors a covering of fibrous
material which is saturated with a compound composed of native bitumen or
asphaltum having paraffin oil or residuum of petroleum, or candle tar mixed
therewith, which not only forms a more efficient, durable, and permanent insulating
material than any which has heretofore been employed for similar purposes, but
which can be prepared at a much smaller cost.
The principal requisites in a material which is to be applied in this manner to
the fibrous coating of a telegraphic conductor are as follows:-
First. It must be a non conductor of electricity and a ropellent of moisture.
Second. It must be tenacious and flexible to a considerable degree, even at a
low temperature, so as to admit of the conductor being bent or twisted without
injury to its covering, and
Third. It must not be capable of softening or volatilizing under continued
exposure to any temperature, which is liable to occur from the action of the sun's
rays when the wire is placed in an exposed position, as upon the roof of a house.
The materials which have hitherto been employed for the purpose of insulating

page_text: telegraphic conductors are composed in part of volatile ingredients, and after
having been exposed for a time to the influence of the atmosphere, or the rays of
the sun, these volatile substances evaporate, and the compound becomes brittle and
liable to crack; the cracks thus formed admit and retain moisture, which has the
effect of greatly impairing the insulation of the conductor, and finally of destroying
it altogether.
In order to obviate these objections I employ for the purpose of saturating the
coating of the conductor a substance which contains no volatile ingredients what-
ever, such a substance, for example, as native bitumen or asphaltum, by preference.
As native bitumen however when used alone for this purpose is somewhat too
hard and brittle, and would consequently be liable to crack when exposed to the
action of the elements, I soften it and at the same time render it tenacious and
durable by incorporating with it a suitable non volatile or non-drying liquid
material, such as paraffin oil, petroleum tar, or candle tar. These three are residual
products obtained by the distillation of petroleum and candle stock respectively, and
since it requires a very high temperature to effect this distillation, the residuums
are of such a nature that they do not thereafter undergo any change from the
influence of the atmosphere when exposed thereto.
The proportion in which I mix the native bitumen and paraffin oil, candle tar,
or residuum of petroleum together, depends on the nature or character of the
bitumon, and the place in which the insulated conductor is designed to be used.
A very suitable compound for ordinary purposes may be made of sixty five parts
Trinidad asphaltum mixed with fourteen parts of petroleum, but this proportion
may be considerably varied, as hereinbefore stated.
In order to prepare an insulated conductor 1 take a suitable wire of copper or
other metal, and cover the same with a continuous coating of clean, dry, fibrous
material, such as hemp or manilla, which may be spun, woven, or braided, or
applied in any other convenient manner. This process of covering the wire is well
understood and therefore need not be herein particularly described. The wire thus
prepared is then saturated or coated with the compound hereinbefore described,
preferably passing the wire through a quantity of material which is kept in a
liquid condition by the application of heat. If desired, a second or even a third
coating of the fibrous material may be applied and each necessarily saturated in
the same manner. A conductor thus prepared is ready for use, it being provided
with a flexible waterproof and non conducting covering, which is practically
indestructible by the means of ordinary atmospheric agencies, and may therefore be
suspended in the air or laid under the surface of the earth or submerged in water,
notwithstanding which the conducting wire will be effectively insulated from all
surrounding substances or media of whatever nature.
In cases in which it is required to join the ends of two separate conductors
insulated in the manner above described, I remove the entire coating for a short
distance at the end of each wire, and splice or join the ends in the usual manner;
the joint is then protected and insulated by being wrapped with narrow strips of
loosely woven cloth or tape, which have been previously saturated with the
compound in the manner already described. In preparing the insulating compound,
a certain portion of resin might be substituted for an equivalent portion of the
native bitumen or asphaltum.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Elijah Marshall Allen in the Great Seal Patent Office on the
28th September 1880.
ELIJAH MARSHALL ALLEN, of Botolph Lano, in the City of London. " IMPROVE-
MENTS IN INSULATING ELECTRICAL CONDUCTORS." A communication from abroad
by Adolphus A. Knudson, and Frederick L. Kane, both of Brooklyn, in the County
of Kings, and State of New York, United States of America.
This Invention relates to an insulating coating for enveloping and protecting
electrical conductors, more especially such conductors as are designed for telegraphic
purposes, and are therefore required in some instances to be suspended in the air,
and in other cases to be buried in the earth or submerged in water.
The Invention consists in applying to the conductors a covering of fibrous
material, which is saturated with a compound composed of native bitumen or
asphaltum having paraffin oil or residuum of petroleum or candle tar mixed
therewith, which not only forms a more efficient, durable, and permanent insulating
material than any which has heretofore been employed for similar purposes, but
which can be prepared at a much smaller cost.
The principal requisites in a material which is to be applied in this manner to
the fibrous covering of a telegraph conductor are as follows:-(1) It must be a
non-conductor of electricity and a repellant of moisture; (2) it must be tenacious
and flexible to a considerable degree, even at a low temperature, so as to admit of
the conductor being bent or twisted without injury to its covering; and (3) it must
not be capable of softening or volatilising under continued exposure to any
temperature, which is liable to occur from the action of the sun's rays when the
wire is placed in an exposed position, as upon the roof of a house.
The materials which have hitherto been employed for the purpose of insulating
telegraphic conductors are composed in part of volatile ingredients, and after having
been exposed for a time to the influence of the atmosphere or the rays of the sun
these volatile substances evaporate, and the compound becomes brittle and liable to
crack; the cracks thus formed admit and retain moisture, which has the effect of
greatly impairing the insulation of the conductor, and finally of destroying it
altogether. In order to obviate these objections I employ for the purpose of
saturating the covering of the conductor a substance which contains no volatile
ingredients whatever, such a substance, for example, as native bituinen or
asphaltum by preference. As native bitumen however when used alone for this
purpose is somewhat too hard and brittle, and would consequently be liable to
crack when exposed to the action of the elements I soften it, and at the same time
render it tenacious and durable by incorporating with it a suitable non-volatile or
non-drying liquid material, such as paraffin oil, petroleum tar, or candle tar. These
three are residual products obtained by the distillation of petroleum and candle-
stock respectively, and since it requires a very high temperature to effect this
distillation, the residuums arc of such a nature that they do not thereafter undergo
any change from the influence of the atmosphere when exposed thereto.
The proportion in which I mix the native bitumen and paraffin oil, candle tar,
or residuuin of petroleum together, depends on the nature or character of the
bitumen and the place in which the insulated conductor is designed to be used.
A very suitable compound for ordinary purposes may be made of 65 parts
Trinidad asphaltum mixed with 14 parts of petroleum residuum, but this proportion
may be considerably varied, as hereinbefore stated, and a certain portion of
resin might be substituted for an equivalent portion of the native bitumen or
asphaltum.
In order to preparo an insulated conductor I take a suitable wiro of copper or
other metal, and cover the same with a continuous covering of clean, dry, fibrous

page_text: material, such as hemp or manilla, which may be spun, woven, or braided, or applied
in any other convenient manner, as shown in Figure 1 of the accompanying
Drawings. This process of covering the wire is well understood and therefore need
not be herein particularly deecribed. The covering of the wire is then saturated
or coated with the compound hereinbefore described, preferably by passing the
covered wire through a quantity of material, which is kept in a liquid condition by
the application of heat. If desired a second or even a third covering of the fibrous
material may be applied, and each necessarily saturated in the same manner.
conductor thus prepared is ready for use, and being thus provided with a flexible
water proof and nonconducting covering, which is practically indestructible by
ordinary atmospheric agencies, it may be suspended in the air or laid under the
surface of the carth, or submerged in water, and under these circumstances will
be effectually insulated from all surrounding substances or media of whatever
nature.
A
In cases in which it is required to join the end of two separate conductors
insulated in the manner above describod, I remove the entire covering for a short
distance at the end of each wire, and splice or join the ends of the wire in the
usual manner; the joint is then protected and insulated by being wrapped with
narrow strips of loosely woven cloth or tape, which have been previously saturated
with the compound in the manner already described, the mode of such application
to a joint being shown in Figure 2.
Having described the nature of the said Invention and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
hereinbefore in part recited Letters Patent is,―
1st. An electrical conductor insulated by a covering of a fibrous material, which
is coated or saturated, or both, with a waterproof, flexible, adhesive compound
composed of Trinidad or other natural asphaltum mixed with paraffin oil, petrolcum
residuum, candle tar, or other non-drying and softening material, substantially as
specified.
2nd. An insulating compound for coating telegraphic conductors consisting of
native bitumen or asphaltum mixed with paraffin oil, petroleum residuum, or candlo
tar, substantially as specified.
In witness whereof, I, the said Elijah Marshall Allen, have hereunto set my
hand and seal, this Sixteenth day of September, in the year of our Lord
One thousand eight hundred and eighty.