A Improvements in Electric Capies.
Year: 1897

page_text: Date of Application, 22nd Jan.,
1897
Complete Specification Left, 21st Oct., 1897 -Accepted, 22nd Jan., 1898
A
Improvements in Electric Capies.
We, WILLOUGHBY STATHAM SMITH, of 13, Courtfield Road, South Kensington,
n the County of Middlesex, Telegraphic Engineer, and WILLIAM PUDDICOMBE
GRANVILLE, of 36, Oakfield Road, Stroud Green in the same County, Electrician,
do hereby declare the nature of this invention to be as follows:-
This invention relates to that class of cable in which there are two or more in-
sulated conductors contained in an insulating sheath and forming a metallic
circuit or circuits and especially to the cables described in our specification No.
8573 of 1895.
It is well known that the possible speed of transmission is increased by having
one or more leaks connecting the two parts of a circuit for instance between the
conductor and the sea when the sea is used as the return part of the circuit or
between the two conductors in the case of a two conductor cable used as a metallic
circuit. For the purpose of providing an artificial leak or leaks we take advantage
of the conduit or longitudinal air-space in air-space cables such for example as
are described in our specification No. 8573 of 1895 using it as a convenient recep
tacle for enclosing the leak producing apparatus which leak apparatus may consist
of a length of fine wire or ribbon either straight or coiled and if coiled either with
or without an iron axis and having the necessary electrical resistance one end of
the leakage wire or ribbon being connected to one wire of the circuit and the
other end to the other wire of the circuit or for the same purpose we coat the out-
side of the insulation of each conductor with some bad conductor such as plumbago
and also make holes in it exposing the conductors alternately at points some dis-
tance apart.
Or instead of the coating, the space or interstices inside the sheath may be
filled with a liquid of high resistance such as water. In the case of a cable having
more than one circuit stops are placed between the bared points in different cir-
cuits and this may be done in all cases.
When cables having air spaces such as are described in our former specification
are employed in deep water the pressure is apt to collapse the air space and to
prevent this we fill the space with wax gum resin or other liquid or solid material
of low specific inductive capacity. When the material has a low melting point
as is preferred this may be done by liquefying the material and pumping it into
the cable whilst the latter is in a warm chamber. Magnetic substances may
also be mixed with the materials. The liquid referred to in preceding paragraph
also serves the same purpose.
It is well known that many liquid or semi-liquid substances such as Stockholm
tar, carbolic acid and alcohol have the property of decreasing the electrical re-
sistance of gutta percha and we therefore in some cases use them for filling the
space or interstices as above described.
In order to render the low inductive capacity of air space cables more permanent

page_text: we coat the insulation of the conductor with insulating varnish and where a
badly conducting coating is used this varnish is preferably applied over it.
Dated this 22nd day of January 1897.
WILLOUGHBY S. SMITH.
W. P. GRANVILLE.
improvements in Electric Cables.
We, WILLOUGHBY STATHAM SMITH, of 13, Courtfield Road, South Kensington,
in the County of Middlesex, Telegraphic Engineer, and WILLIAM PUDDICOMBE
GRANVILLE, of 36, Oakfield Road, Stroud Green in the same County, Electrician,
do hereby declare the nature of this invention, and in what manner the same is to
be perforined, to be particularly described and ascertained in and by the following
statement:-
This invention relates to that class of cable in which there are two or more in-
sulated conductors contained in an insulating sheath and forming a metallic
circuit or circuits and especially to the cables described in our specification
No. 8573 of 1895.
It is well known that the possible speed of transmission is increased by having
one or more leaks connecting the two parts of a circuit for instance between the
conductor and the sea when the sea is used as the return part of the circuit or
between the two conductors in the case of a two conductor cable used as a metallic
circuit. For the purpose of providing an artificial leak or leaks we take advantage
of the conduit or longitudinal air-space in air-space cables, such for example as
are described in our specification No. 8573 of 1895 using it as a convenient recep-
tacle for enclosing the leak producing apparatus which leak apparatus may consist
of a length of fine wire or ribbon either straight or coiled and if coiled either with
or without an iron axis and having the necessary electrical resistance one end of
the leakage wire or ribbon being connected to one wire of the circuit and the
other end to the other wire of the circuit.
a a
Figures 1, 2 and 3 are longitudinal sections, and Figures 4, 5 and 6 transverse
sections, all to an enlarged scale, of three cables made according to this invention.
are the conductors, 6 a metallic wire or ribbon connecting them and c
(Figures 1 and 4) an iron core. As described in our former specification the con-
ductors are first embedded in the segments dd which are then brought together.
In the machine the segments dd just before they come together are inclined at
an angle to each other thus leaving a space which permits of the ends of the
wire 6 being successively soldered to the conductors a. After the segments have
been brought together they are covered with the layers e as before.
Or for the same purpose we coat the outside of the insulation of each con-
ductor with some bad conductor such as plumbago and also make holes in it
exposing the conductors alternately at points some distance apart.
The number and dimensions of the leakage resistances inserted in the air-space
conduit may, even for cables of one and the same length and conductor resistance,
vary within large limits, it being well understood that although the definition of
the signals is improved by increasing the number of distributed leaks the signals
are diminished in amplitude. The possible number of distributed leaks will. de-
pend therefore not only upon the resistance and electrostatic capacity of the cable
but also upon the sensitiveness of the receiving instrument intended to be used.
In the case of an air-space cable having two conductors used as a metallic circuit

page_text: ithout "earth," then if we suppose the cable to be 2000 nautical miles in length
aving a total resistance for the whole circuit of 8000 Ohms, we may insert at
qual distances in and along the air-space conduit 200 leakage wires or ribbons,
r leakage connections by plumbago or the like-with or without stops of insula-
ing material between each leakage connection-the resistance of each leakage
ircuit being say 250,000 Ohms.
If the cable instead of having only one pair of conductors has two or more pairs,
each pair being used as a metallic loop, then each pair of conductors is provided
with its own separate and distinct series of leakage resistances, it being con-
venient to insert the leakage resistance of each pair in rotation in and along the
air-space conduit.
Or instead of the coating the space or interstices inside the sheath may be filled
In the case of a cable having more
with a liquid of high resistance such as water.
than one circuit stops consisting of short plugs of insulating material inserted in
the hollow of the cable during the process of manufacture are placed between the
bared points in different circuits and this may be done in all cases.
When cables having air-spaces such as are described in our former specifica-
tion are employed in deep water the pressure is apt to collapse the air-space and to
prevent this we fill the space with wax gum resin or other liquid or solid material
of low specific inductive capacity. When the material has a low melting point
as is preferred this may be done by liquefying the material and pumping it into
the cable whilst the latter is in a warm chamber.
Magnetic substances such as filings of the magnetic metal, preferably iron or
magnetic oxide of iron may also be mixed with the materials. The liquid referred
to in preceding paragraph also serves the same purpose.
It is well known that many liquid or semi-liquid substances such as Stockholm
tar, carbolic acid and alcohol have the property of decreasing the electrical re-
sistance of gutta percha and we therefore in some cases use them for filling the
space or interstices as above described.
In order to render the low inductive capacity of air space cables more permanent
we coat the surface of the insulation of the conductor in the air space with insulating
varnish or wax, and where a badly conducting coating is used this varnish is pre-
ferably applied over it.
Having now particularly described and ascertained the nature of our said
5 invention and in what manner the same is to be performed, we declare that what
we claim is:-
1. Air space cables in which the circuit wires are connected together by con
ductors of high resistance substantially as described.
2. Cables in which the space between the circuit wires is filled with liquid o
40 high resistance in contact in places with the wires substantially as described.
filled with a liqui
3. Cables in which the space between the circuit wires
or solid material of low specific inductive capacity substantially as described.
4. Cables in which the space between the conductors is filled with a materia
having the property of decreasing the electrical resistance of gutta percha sub
45 stantially as described.
5. Air space cables in which the insulation of the conductors in the air spac
is coated with insulating varnish or wax substantially as described.
6. Cables substantially as described and shown in the drawings.
1007
WILLOUGHBY S. SMITH.
W. P. GRANVILLE.