IMPROVEMENTS IN ELECTRIC TELEGRAPH CABLES, AND IN INSULATING TELEGRAPH CONDUCTORS
Year: 1873

page_text: LETTERS PATENT to Christian Ludvig Madsen, of Copenhagen, in
the Kingdom of Denmark, at present residing at 21, Suffolk
Street, Pall Mall, in the County of Middlesex, for the Invention
of "IMPROVEMENTS IN ELECTRIC TELEGRAPH CABLES, AND IN INSULATING
TELEGRAPH CONDUCTORS.”
Sealed the 20th February 1874, and dated the 18th December 1873.
PROVISIONAL SPECIFICATION left by the said Christian Ludvig
Madsen at the Office of the Commissioners of Patents, with his
Petition, on the 18th December 1873.
I, CHRISTIAN LUDVIG MADSEN, of Copenhagen, in the Kingdon of
Denmark, at present residing at 21, Suffolk Street, Pall Mall, in the
County of Middlesex, do hereby declare the nature of the said In-
vention for "IMPROVEMENTS IN ELECTRIC TELEGRAPH CABLES, AND IN INSULATING
TELEGRAPH CONDUCTORS," to be as follows:-
The object of this Invention is mainly to construct electric telegraph
cables and other electric telegraph conductors at less cost and with

page_text: higher working powers than those now made. For this purpose I
employ as the insulating material for surrounding the metallic con-
ductors a compound composed of wax, resin, paraffin, and turpentine,
small proportions of other fats, or oils, or greases, may be added to the
compound to render it harder or softer, as required, according to the
temperatures to. which it will be subjected. This compound may be
applied around the conductor in a variety of ways. I prefer however
to pass the conductor through a bath of the melted compound to give
to it a coating of the compound and fill up the interstices between the
several wires of which it is composed; or the several wires or strands
might be passed separately tnrough a bath of the compound and then
made up into one conductor with or without fibrous matter around the
central wire or around all of them. Afterwards a tape of fibrous
material is wound spirally around the coated conductor, or fibrous
material is otherwise laid around it; and it is then again passed through
a bath of the compound, and fibrous material again applied, and so on
until the conductor has been surrounded with a sufficient thickness of
the insulating compound.
The proportions of the various materials forming the compound in the
several baths may be varied according to the degree of hardness they
are desired to possess.
The insulating compound above described posseses sufficient insulating
power, together with extremely low inductive capacity, and by reason
of the low cost at which it can be made and applied much larger
metallic conductors may be employed than is now usual, so that if
desired conductors of iron wire may be used.
I also in some cases use a central wire or strand of copper with iron
wires around it, or a central strand of iron with copper around it, not
only for the sake of cheapness but also for adding strength to the
cable.
The iron wires or strands may be galvanized or coated if desired.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Christian Ludvig Madsen in the Great Seal Patent
Office on the 17th June 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHRISTIAN
LUDVIG MADSEN, of Copenhagen, in the Kingdom of Denmark, at
present residing at 21, Suffolk Street, Pall Mall, in the County of
Middlesex, send greeting.
+
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eighteenth day of December, in the
year of our Lord One thousand eight hundred and seventy-three, in the
thirty-fourth year of Her reign, did, for Herself, Her heirs and
successors, give and grant unto me, the said Christian Ludvig Madsen,
Her special license that I, the said Christian Ludvig Madsen, my exe-
cus, administrators, and assigns, or such others as I, the said
Christian Ludvig Madsen, my executors, administrators, and assigns,
should at any time agree with and no others, from time to time and
at all times thereafter during the term therein expressed, should and
lawfully might make, use, exercise, and vend, within the United
Kingdom of Great Britain and Ireland, the Channel Islands, and Isle
of Man, an Invention for "IMPROVEMENTS IN ELECTRIC TELEGRAPH Cables,
AND IN INSULATING TELEGRAPH CONDUCTORS," upon the condition (amongst
others) that I, the said Christian Ludvig Madsen, my executors or
administrators, by an instrument in writing under my, or their, or one
of their hands and seals, should particularly describe and ascertain the.
nature of the said Invention, and in what manner the same was to be
performed, and cause the same to be filed in the Great Seal Patent
Office within six calendar months next and immediately after the date
of the said Letters Patent..
NOW KNOW YE, that I, the said Christian Ludvig Madsen, do hereby
declare the nature of the said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement thereof, that is to say :-
-
The object of this Invention is mainly to construct electric telegraph
cables and other electric telegraph conductors at less cost: and with

page_text: higher working powers than those now made. For this purpose I
employ as the insulating material for surrounding the metallic con-
ductors a compound composed of wax, resin, paraffin, and turpentine,
small proportions of other fats, or oils, or greases, may be added to the
compound to render it harder or softer, as required, according to the
temperatures to which it will be subjected. This compound may be
applied around the conductor in a variety of ways.
.
In manufacturing an electric telegraph cable I proceed as follows:-
I take tapes of fibrous materials, either made for the purpose or cut from
suitable cloth and of suitable widths and lengths, and prepare them
simply by dipping them in the melted insulating compound and leaving
them until they are quite saturated with the compound, after which
they are taken out and left to cool; the tapes are then ready for use,
or they are given a second coating of the compound by quickly passing
them through the bath again, which process may be repeated if desired.
Between the first and second coating the tapes may be stretched or not,
and passed between rollers or not, as may be desired.
8
The compound used for preparing the tapes I prefer to form of about
1 part (by weight) of wax, ½ of resin, ¾ of paraffin, ½ of crude
turpentine, to which is added ¾ of tallow. The tapes are prepared in
this compound at a temperature of about 300 degrees of Fahrenheit for
the first coating, and at a somewhat lower temperature for the next
coating; but to obtain the best results it is of great importance that the
compound should be heated to a temperature of nearly 300° for the first
saturation of the tapes, as otherwise the complete saturation of the tape
is not effected with certainty. Tapes prepared in the above compound
I prefer to use next the conductor, and around these may be a coating
of tapes saturated with a compound consisting of about one part
Stockholm pitch, ¼ wax, ¼ tallow, and around this again may be
another layer of tape saturated with the first-mentioned insulating
compound; but this arrangement may be altered or modified according
to circumstances, such for example as thickness of dielectric required.
The metallic conductor composed of a solid wire or of stranded
wires is likewise dipped in a bath of melted compound to fill up the
interstices between the several wires of which it is composed, and to
give to it a coating of the compound.

page_text: The metallic conductor is served and the core manufactured as here-
after described. The prepared tapes, slightly warmed, are wound on
reels to be fixed on discs, which are made to revolve round the conductor
as the same passes along, and thus covering the same. More or less
friction applied to the reels by means of a spring causes the tape to
be laid more or less tightly round the core, and the revolution of the
disc is regulated according to the length of lay desired. The disc as
well as the reel is kept slightly warmed by means of gas, or otherwise,
during the process of covering the core.
The conductor for the purpose
of being covered is placed in a bath of melted compound, generally the
first of the above-named compounds; and as it unrolls itself during the
covering and before the first tape is laid on it passes another bath of
melted compound, generally the last of the above-named compounds.
By this process the intertices of the strand of the conductor will be well
filled up and the surface of the conductor acquire a good adhesive
coating. Immediately before the tapes are laid on the conductor or
core passes a metallic cylinder placed inside an iron mantle or chamber,
both heated by means of gas, or otherwise; the heat to be regulated so
as to give just as much as is necessary to render the surface of the
coated conductor fully adhesive, and to secure a good adhesion between
the different layers.
In case of the machinery stopping the gas is turned off. In this
manner as many layers are laid on as required to give the conductor a
sufficient thickness of the insulating material. Immediately after the
last of the prepared tapes has been laid on, a plain tape of dry fibrous
material is laid tightly round the core, after which the core is passed
between a set of rollers, and the core is thus completed.
Instead of having heat applied as named above the core may be passed
through a bath of melted compound, or both processes may be used
simultaneously. The compound is then kept at the desired temperature
(say 200 degrees of Fahrenheit) in an iron vessel of sufficient length
and provided with three rollers, the core to pass over the first and third
and under the middle one, which is fixed so as to allow the core to be
quickly taken out of or replaced in the bath when required.
A sufficient number of reels provided with prepared tapes should be
at hand on stands placed near the covering machines, and the reels and

page_text: 'stands kept at a suitable temperature. Small basins containing a
quantity of melted compound at a temperature of about 200° Fahrenheit
should also be placed near the covering machine, in order that the ends
of new tapes to be laid on may be dipped in or provided with compounds
from this basin to secure their adhesion to the tape already laid on.
E
A core constructed as above described is hard and pliable, and is not
liable to get eccentric on account of the tapes laid tightly round the
conductor; joints in the dielectric can also easily be made by means
of tapes prepared beforehand, and only require a short time to make.
The plain tape laid firmly round the finished core or joint will by its 1
contraction when put into water render a uniform pressure round the
core, thus solidifying the same.
The common and cheap substances forming the insulating compound,
as described above, are known to be in posesssion of qualities of the
highest value for telegraph cables and insulated telegraph wires, such 1
as low inductive capacity combined with great insulating power. As
the materials forming the dielectric are easy to obtain, and do not
require any refining processes, but can be used for insulating purposes
just as they are bought in the market; and as they further can be
applied at a low cost, and by machinery of the simplest description, it 2
follows that telegraph cables and other electric telegraph conductors can
be constructed at much less cost and with higher working power than
those now in use. It must be particularly observed that the increase
in the bulk of this dielectric causes only a slight increase in the cost
of the same. Heavy telegraph conductors can therefore with great 2
advantage be employed in long submarine telegraph cables without
materially increasing the inductive capacity or the cost of the dielectric ;
but in thus improving the essential part of the cable, most valuable
improvements in the speed, in the mode of working, and in the con-
struction of telegraph cables, may be acquired.
3

page_text: 2. The employment of compounds of wax, resin, or resinous matters,
paraffin, and, turpentine, for insulating the conductors of electric
telegraphs, substantially as described.
In witness whereof, I, the said Christian Ludvig Madsen have
hereunto set my hand and seal, this Sixteenth day of April, in the
year of our Lord One thousand eight hundred and seventy-four.
C. L. MADSEN. (L.S.)