IMPROVEMENTS IN AND RELATING TO ELECTRICAL CABLES OR LINES FOR TELEGRAPHIC, TELEPHONIC, AND OTHER PURPOSES
Year: 1881

page_text: LETTERS PATENT to Henry Harris Lake, of the Firm of Haseltine, Lake,
& Co., Patent Agents, Southampton Buildings, London, for an Invention
of "IMPROVEMENTS IN AND RELATING TO ELECTRICAL CABLES OR LINES
FOR TELEGRAPHIC, TELEPHONIC, AND OTHER PURPOSES." A communication
from abroad by John Benjamin Henck, junior, of Boston, Massachusetts, United
States of America.
PROVISIONAL SPECIFICATION left by the said Henry Harris Lake at the
Office of the Commissioners of Patents on the 20th September 1881.
HENRY HARRIS LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. "IMPROVEMENTS IN AND RELATING TO
ELECTRICAL CABLES OR LINES FOR TELEGRAPHIC, TELEPHONIC, AND OTHER
PURPOSES." [A communication from abroad by John Benjamin Henck, junior, of
Boston, Massachusetts, United States of America.]
In electric cables, and to some extent in other lines, for electric communication
as heretofore constructed with one or more continuous conductors from end to end,
a retardation of signals is encountered, which increases according to the following
rule, that is to say, nearly in proportion to the square of the length of the cable,
and this retardation becomes especially troublesome when it is necessary to make
use of rapidly alternating currents in opposite directions, as, for instance, telephonic
purposes, the difficulty then encountered being so great as to practically forbid the
use of telephones beyond a limited distance. In the case of ocean cables this limit
is generally reached at the end of from five to twenty miles, according to the
special construction of the cable and instruments.
The object of the present Invention is to diminish this retardation and thus
render telephones available for use over lines and cables of greater length, and
at the same time to increase the rapidity of action and efficiency of all other
forms of electrical instruments used in connection with such lines and cables.
According to the rule above stated if a cable be divided into, say, ten sections,

page_text: the retardation in each section will be only one hundredth part of that in
the whole cable when made in one piece, and in the ten sections together it will
be ten hundredths or one tenth that of the whole. It has been heretofore
attempted to obtain this advantage by connecting two or more sections of cable
by means of mechanical relays. According to the present Invention however the
electric impulses are communicated from one section to the next by static induction.
This object may be accomplished by simply inserting a condenser at each break
in the cable and connecting the two adjacent sections of the conductor to its opposite
coatings, but this cannot be regarded as practicable by reason of the great bulk
and weight of such condensers, and the inconvenience and risk attending the
submergence of a cable so constructed. I therefore accomplish my object without
interruption of the external continuity of the cable by causing the several sections
into which the conductor is divided to overlap each other in the manner herein-
after described, and by this arrangement I obtain the further advantage of increased
rapidity of action as compared with a line or cable composed of sections united
by condensers of the ordinary construction, as it will be readily understood that a
charge of electricity entering upon one section of my improved cable or line
immediately begins to produce its inductive effect upon the next section, instead
of this effect being delayed until the inducing charge reaches the extreme end
of the first section, as must be the case with any other construction hitherto
proposed.
The
In carrying the said Invention into practice I construct a cable or line of a series
of overlapping conductors. These conductors may consist of two sets of flat metal
strips or ribbons, which are separated by suitable insulating material.
operation is as follows, that is to say: Supposing a positive charge is communi-
cated to the first conductor a negative charge will be immediately induced upon
the overlapping portion of the adjacent or second conductor, and a positive charge
will be repelled to the farther extremity or part of the said conductor, where
it will in its turn induce a negative charge upon the overlapping portion of the
next or third conductor at the same time repelling a positive charge to the
farther portion of the said conductor, and this action will continue to the end of
the cable, where the charge may be employed to actuate any suitable receiving
instrument.
Instead of using but two sets of metal strips or ribbons, as above described, I
may use three sets, the two outside strips in this case acting together as one, and
the action of the said strips when combined being precisely similar to that above
described.
of
Further, instead of flat strips I may use a series of wires and surrounding tubes,
and in place of continuing the second conductor on the outside of the third, as
above described I may cause the farther half of each conductor to enter between
or within the overlapping portion of the next conductor in the series. Moreover,
the aforesaid metal strips or ribbons may be corrugated for the purpose
presenting a greater surface for inductive action, and instead of employing a series
of wires and surrounding tubes, as above described, the said wires may be replaced
by a tube for the same purpose. It is evident that these tubes may have their
surfaces further increased by corrugating them in the same manner as the metal
strips or ribbons.
In some cases two strips or ribbons may be coiled together in spiral form for the
purpose of increasing the inductive surface, whilst at the same time keeping the
bulk and the external surface of the cable or line as small as possible.
In some
cases also the surrounding tubes above described may be replaced by a covering of
small wires. This arrangement facilitates the manufacture of the cable and imparts
greater flexibility to the latter.
For certain purposes the conductors constructed as above described may be used
without further addition, excepting in the case of lines composed of flat metal
strips or ribbons, in which case the insulating material must either serve also as a
cement or a serving or wrapping of cord or small wire must be used to bind the

page_text: plates together.
In the case of aerial lines additional strengthening of the
parts where the conductor is broken would be necessary and may be easily
accomplished by thickening the remaining conductor or by adding an external
covering.
If the line is to be laid underground, or under water, or in close contact with
other lines, a covering of insulating material must be added, the nature of this
covering being determined by the special circumstances under which the line is to
be used. It will generally be necessary to further protect this insulating covering
by an armour or sheathing of metal, this armour in the case of submarine cables
also serving to give the necessary strength to the whole.
This armour may be
composed of metallic wires. In some cases the transmitting conductors may be
surrounded by insulating material and the whole enclosed in a tube or pipe of lead
or other metal; this construction is especially suited to underground systems. Or
the transmitting conductors may be protected by both a tube and a wire armour,
the former forming a waterproof covering, and the latter a strengthening and
protective covering. In this case it is desirable to ensure the adhesion of the wire
armour to the said tube either by making the tube so thin as to be impressed
and slightly corrugated by the wire as it is laid on, or by inserting a covering of
hemp or other yielding material between the said tube and wire armour.
I also construct a cable containing three independent lines of transmission. Each
line is surrounded by independent insulating and metallic coverings, and the whole is
bound together by a common armour. The independent metallic coverings around
the several lines are intended to prevent inductive interference between the lines,
and unless these coverings are thick their efficiency as induction screens should
be further increased by connecting them with the earth either throughout their
length, or at least at frequent intervals.
In the working of a cable of any of the above forms a portion of the initial
force will obviously be lost by inductive action between the plates, wires, or tubes
of the transmitting system and the surrounding earth, water, metal armour, or
induction screens, and it is desirable to reduce this loss to a minimum by making
the insulating material between the successive conductors as thin as practicable
relatively to that between the conductors and the outside of the cable, and also
by using between the conductors insulating material of as high specific inductive
capacity as possible, such as mica, glass, or the like, and outside of them a
material of comparatively low specific inductive capacity, such as hemp, jute, or
other vegetable substance.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Henry Harris Lake in the Great Seal Patent Office on the
20th March 1882.
HENRY HARRIS LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. "IMPROVEMENTS IN AND RELATING TO
ELECTRICAL CABLES OR LINES FOR TELEGRAPHIC, TELEPHONIC, AND OTHER
PURPOSES." A communication from abroad by John Benjamin Henck, jun., of
Boston, Massachusetts, United States of America.
In electric cables and to some extent in other lines for electric communication as
heretofore constructed with one or more continuous conductors from end to end, a
retardation of signals is encountered which increases according to the following rule,
that is to say, nearly in proportion to the square of the length of the cable, and
this retardation becomes especially troublesome when it is necessary to make use of
rapidly alternating currents in opposite directions, as for instance for telephonic
purposes, the difficulty then encountered being so great as to practically prevent
the use of telephones beyond a limited distance. With submerged cables this limit
is generally reached at the end of from five to twenty miles, according to the
special construction of the cable and instruments.-
The object of the present Invention is to diminish this retardation, and thus
render available for telephonic purposes lines or cables of greater length than those
heretofore practicable, and at the same time to increase the rapidity of action and
efficiency of all other forms of electrical instruments used in connection with such
lines and cables.
According to the rule above stated, if a cable be divided into, say, ten sections,
the retardation in each section will be only one hundredth part of that in the
whole cable when made in one piece, and in the ten sections together it will be ten
hundredths or one tenth that of the whole. It has been heretofore attempted to
obtain this advantage by connecting two or more sections of cable by means of
mechanical relays. According to the present Invention, however, the electric
impulses are communicated from one section to the next by static induction. This
object may be accomplished by simply inserting a condenser at each break in the
cable, and connecting the two adjacent sections of the conductor to its opposite
coatings, but this device cannot be regarded as practicable by reason of the great
bulk and weight of such condensers, and the inconvenience and risk attending the
submergence of a cable so constructed. I therefore accomplish my object without
interruption of the external continuity of the cable, by causing the several sections
into which the conductor is divided to overlap each other in the manner hereinafter
described; and by this arrangement I obtain the further advantage of increased
rapidity of action as compared with a line or cable composed of sections united by
condensers of the ordinary construction, as it will be readily understood that a charge
of electricity entering upon one section of my improved cable or line immediately
begins to produce its inductive effect upon the next section, instead of this effect
being delayed until the inducing charge reaches the extreme end of the first
section, as must be the case with any other construction hitherto proposed.
Referring to the accompanying Drawing,
Figures 1, 2, 3, 4, illustrate in longitudinal section, and Figures 1, 2, 3, 4, 4b,
in transverse section, the construction of various forms of telegraphic lines according
to my Invention.
The remaining Figures are hereinafter described.
It will be obvious from the following description that these Figures only

page_text: illustrate the relative position of the conductors, and afford no idea of the length of
the same.
Figures 1 and 1° represent a telegraphic line composed of a series of overlapping
conductors arranged according to my Invention. The conductors in this case are
represented in the form of flat plates, which are separated by suitable insulating
material. The action will be as follows, that is to say, supposing a positive charge is
communicated to the first conductor a, a negative charge will be immediately
induced upon the overlapping portion of the second conductor b, and a positive
charge will be repelled to the farther extremity or part of the said conductor b,
where it will in its turn induce a negative charge upon the overlapping portion of
the third conductor c, at the same time repelling a positive charge to the farther
portion of the said conductor c, and this action will continue through the con-
ductors d, e, f, and to the end of the cable, where the charge may be employed to
actuate any suitable receiving instrument.
The instruments for transmitting and receiving the signals or messages are to
be connected between the extremities or ends of the cable and the earth, or may
be used without earth connections, according to their construction and mode of
operation, in the same manner as with ordinary electrical cables.
Instead of using but two series of plates, as above described, I may use three
series, as shown in Figures 2 and 2a, the two outside plates 6 in this case acting
together as one conductor, and the inductive action of the said plates being precisely
similar to that of the single plates above described.
Instead of flat plates I may use a central wire or series of wires and surrounding
tubes, as shown in Figures 3, 3, and in this form of cable in place of continuing the
second conductor b over the outside of the third conductor c, as above described
and shown, I may arrange the end of each conductor to enter between or within
the overlapping portion of the next conductor in the series, as shown in Figure 4.
This modification of my Invention may be adapted to a cable constructed with
tubes, as shown in Figure 4ª, or with plates, as in Figure 4b.
Figures 5, 6, 7, 8, 9, illustrate in transverse section various other modifications
of my Invention.
Figures 5 and 6 show a modification wherein the plates used in the manner
described with reference to Figures 1 and 2 are corrugated for the purpose of
presenting a greater surface for inductive action. In the cable shown in Figure 7,
the central wire specified with reference to Figure 3 is replaced by a tube b* for
the same purpose. It is evident that these tubes may also have their surfaces
increased by corrugating them.
Figure 8 shows two plates coiled together in spiral form for the purpose of
increasing the inductive surface, whilst at the same time keeping the bulk and the
external surface of the cable or conductor as small as possible.
In Figure 9 the tubes represented in Figure 3 are replaced by a covering of
small wires h; this arrangement facilitates the manufacture and increases the
flexibility of the cable.
For certain purposes the conductors, except those shown in Figures 1 and 2,
constructed as above described, may be used without further addition, but in lines
or cables composed of flat plates, as in these Figures, the insulating material must
serve also as a cement, or a serving of cord or small wire must be used to bind the
plates together. In the case of aerial lines additional strengthening of the parts where
the continuity of the conductor is interrupted will be necessary, and may be easily
accomplished by thickening the remaining conductor, or by adding an external
covering.
If the line is to be laid underground or under water, or in close contact with
other lines, a covering of insulating material must be added, the nature of this
covering being determined by the special circumstances in which the line is to
be used. It will generally be necessary to further protect this insulating covering
by an armour of metal, this armour in the case of submarine cables also serving to
give the necessary strength to the whole. One of these forms of my improved

page_text: cable is illustrated in side view and transverse section in Figures 10 and 10ª, thus
prepared for submarine use, the armour shown therein being composed of wire h.
Figures 11 and 11ª show in similar views conductors, such as those represented
in Figure 3, surrounded by insulating material i within a tube or pipe j of lead or
other metal; this construction is especially advantageous for underground systems.
Figures 12 and 12a show also in side view and transverse section conductors,
such as those represented in Figure 8, protected by both a tube j and a wire
armour h, the said tube forming a waterproof covering, and the armour
strengthening and protective covering. In this case it is desirable to ensure the
adhesion of the wire armour to the said tube, either by making the tube so thin
as to be impressed and slightly corrugated by the wire as it is laid on, or by
inserting a covering of hemp or other yielding material, as shown at k, between the
said tube and wire armour.
I prefer to adopt the latter method, and to employ as the material separating
the tube from the armour braided hemp or other fibre or paper saturated with tar,
or the substance known as Chatterton's compound or similar matter; the said
separating material must be sufficiently tough to prevent the wires of the armour
wearing through and coming in contact with the tube, and must also be a
sufficiently good insulator to prevent galvanic action between the armour and the
tube, should they, as will generally be necessary, be made of different metals.
Figure 13 is a transverse section of a cable containing three independent cables,
conductors, or lines of transmission. Each line in this Figure is shown as sur-
rounded by independent insulating and metallic coverings, and the whole is
bound together by the external wire armour h. The independent metallic
coverings around the several lines are intended to prevent inductive interference
between the lines, and unless these coverings are of considerable thickness their
efficiency as induction screens should be further increased by connecting them
with the earth either throughout their length or at least at frequent intervals.
In the working of a cable of any of the above forms, a portion of the initial force
will obviously be lost by inductive action between the plates, wires, or tubes of the
transmitting system, and the surrounding earth, water, metal armour, or induction
screens, and it is desirable to reduce this loss to a minimum by making the
insulating material between the successive conductors as thin as practicable
relatively to that shown at m between the conductors and the outside of the cable,
and also by using between the conductors insulating material of as high specific
inductive capacity as possible, such as mica, glass, or the like, and outside of them
a material of comparatively low specific inductive capacity, such as hemp, jute, or
other vegetable substance.
In employing mica as an insulating substance in the manner here indicated, I
prefer to take a strip of thin paper, tape, or similar material, saturate it with
Chatterton's compound or similar insulating preservative and adhesive substance,
and cover one or both sides of it with scales of mica, the strip so prepared to be
wound spirally about the wire or laid between the plates to be insulated. This
method of protecting a cable by means of a tube, an insulating covering and wire
armour, may be applied with equal advantage to my improved cables, or to other
electric cables or lines.
It is obvious that the length of the several sections into which the conductors in
my improved cables are divided will vary according to the circumstances or
requirements of the line of which they are to form a part, for instance, in the case
of submarine lines they may be from one to fifty miles in length, and for other
lines, particularly those used for telephonic purposes, they may be much shorter.
Having thus fully described the said Invention, and shown how the same may
be conveniently and advantageously carried into practice, I wish it understood
that I do not claim broadly the division of a line of electrical communication into
several parts, as the means for reducing retardation, nor do I claim the trans-
mission of electrical impulses from one portion of such line to another through or
by means of condensers placed between and in connection with such portions,

page_text: as I am aware that both of these devices have previously been used, but I do
claim,―
First. The construction of a cable or line for electrical communication composed
of successive overlapping conductors insulated from and arranged with relation to
cach other, and either with or without the insulating and protective coverings, all
substantially as above set forth and for the purpose specified.
Second. A cable or line for electrical communication constructed as herein
described, and provided with an external insulating covering and with insulating
materials for separating the several conductors, the material for separating the
conductors being of higher specific inductive capacity than that used outside of the
Bame, for the purpose specified.
Third. In the construction of electrical cables, the use of a compound protective
covering consisting of a metal tube, an insulating layer or covering, and an armour
of wire, substantially as and for the purpose set forth.
In witness whereof, I, the said Henry Harris Lake, have hereunto set my
hand and seal, this Twentieth day of March, in the year of our Lord One
thousand eight hundred and eighty two.
HENRY H. LAKE. (L.B.)