IMPROVEMENTS IN AND RELATING TO TELEGRAPHIC CABLES OR CONDUCTORS
Year: 1881

page_text: LETTERS PATENT to William Robert Lake, of the Firm of Haseltine, Lake,
& Co., Patent Agents, Southampton Buildings, London, for an Invention of
IMPROVEMENTS IN AND RELATING TO TELEGRAPHIC CABLES OR CONDUCTORS."
«
A communication from abroad by Patrick B. Delany, of the City and State
of New York. United States of America. Electrician.
PROVISIONAL SPECIFICATION left by the said. William Robert Lake at
the Office of the Commissioners of Patents on the 26th April 1881.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. "IMPROVEMENTS IN AND RELATING TO TELE-
GRAPHIC CABLES OR CONDUCTORS." [A communication from abroad by Patrick
B. Delany, of the City and State of New York, United States of America,
Electrician.]
The object of this Invention is to produce for either underground or overground.
use a telegraph cable, which will be practically unaffected by variations of atmos-
pheric or earth temperature, and in which the conductors will be protected from
the effects of moisture and electrical induction.
Many Inventions have been made looking to the production of a cable of this
character, but experience has proven them to be but partially successful. In some
of these cables the conducting wires have been inclosed in tubes and surrounded
by a fusible resinous insulating material, which is melted and forced into the tubes
around the wires. Such insulating material has been found to be quite easily
affected by even slight changes of temperature, and the tubes are in consequence
warped and often broken and the wires brought in contact with each other or the
tube, and thus rendered useless as conductors. Most of such insulating materials
also undergo chemical decomposition in a short time, and permit or promote the
condensation of moisture upon the wires.
The present Invention consists mainly in protecting the electrical conductors
from moisture by conducting heat by means of a suitable medium in sufficiently
close proximity to said conductors to dissipate all moisture in their immediate
vicinity and prevent its condensation upon them.
The said Invention further consists in a telegraph cable, in which the wires
or conductors are surrounded by powdered talc packed tightly within a tube,

page_text: enclosing both it and the wires. This dry pulverized talc is not liable to be
affected by variations of atmospheric or earth temperature, and therefore the cable
will not be warped, or twisted, or ruptured by contractions and expansions of the
insulating material.
The said Invention also consists in a telegraphic cable composed of an outer and-
an inner tube forming two concentric chambers, in one of which may be arranged
the electrical conductors surrounded by an insulating material, while the other
serves to conduct a flowing heating medium.
In carrying the said Invention into practice the various elements of the cable
are manufactured or prepared in the usual manner, but the cable as a whole, as
composed of these elements, is made as it is laid or arranged for use, and in
substantially the manner described as follows:-
In one way of carrying out my Invention, supposing an underground cable is to
be laid, a trench is dug of the desired depth, say, two or three feet, and on the
bottom of this trench are laid in order the lengths or sections of the outer tube,
these sections being separated from each other by a suitable space for convenience
in working, say, for instance, a suitable number of sections are laid to form a mile
of the cable. I then pass through all these sections a somewhat greater length,
preferably of the iron pipe which is to form the inner tube. I then pass through
the sections the predeterinined number of wires which are to form the electrical
conductors. Ample room should be left at the initial end of the trench for
convenience in working, that is, about a rod should at first be left vacant from the
point where the cable is to begin. The inner tube and wires having been passed
through the outer tube sections, I draw these wires and tube some distance
beyond the initial section, and then string upon said wires and tube a sufficient
number of templets for use in the length of cable to be presently constructed, that
is, one templet for each outer tube section, though more may be used, if desired.
These templets are discs or cylindrical blocks which stand concentric with the tube,
and are perforated for the passage of the wires or conductors, and have a central
- hole for the passage of the inner tube.
The wires being passed through properly coincident apertures of the templets,
the initial section of the outer tube is then moved along in the trench to the place
it is to finally occupy, and all save one of the templets, which have been strung
upon the wires, and inner tube are forced through the initial section of the outer
tube and moved along the wires in advance of said section, so as to be out of the
way of subsequent operations. I then secure the wires and inner tube in any
suitable manner, so that they can not be drawn through the apertures of the first
templet, that is, the one which has not been passed through the initial section of
the outer tube leaving a sufficient length of wires, and inner tube projecting
through said templet for convenience in making connections. The said templet is
then placed so as to close the end of the initial outer tube section, and there
secured by any suitable means, say, for instance, by having a suitable bar secured
to its outer face, which will project radially beyond the tube wall. Or this first
templet may have a rim to fit against the end edge of the tube. Now one of the
templets which had been passed through should be moved up towards the mouth
of the initial or outer tube section, this templet being supported by a shoe at a
little distance from the mouth of the said outer tube section to bring its apertures
in line with those of the templet in the opposite end of the tube, in order that the
wires and inner tube may be held straight. The initial outer tube section is then
ready to receive the insulating material which is to be packed within it. This
insulating material (talc) being coarsely powdered is to be blown in by a suitable
blowing apparatus having a hopper to hold the powdered material.
A hose leads from the hopper, the end of this hose being introduced into the
tube-section nearly the full length of said section, the powdered insulating material
having been previously heated to expel moisture is placed in the hopper and the
blower operated, when the said powdered material will be forced snugly into the
tube, the hose being gradually withdrawn as the filling proceeds. When the tube

page_text: section has been properly filled, say, to within three or four inches, or as near as
practicable to its mouth, the hose is entirely withdrawn, and the templet which
had been placed upon the shoe in front of the tube is forced into the mouth of the
section, and said templet and the insulating material are then rammed in by means
of a ram operating upon a hollow follower which bears upon the templet.
The ramming being completed the apparatus and appliances used therefor are
removed, an additional tube-section is moved up, its end placed in the collar of the
rammed section, and the joint leaded in the ordinary manner.
It is then filled and rammed as was the first section, and the operation is the
same for all succeeding sections.
Any suitable apparatus may be used for filling and ramming the sections without
departing from my Invention.
The length of trench dug and number of tube sections laid to operate upon at
any particular time depends entirely upon convenience.
In order to guard against interruption of the insulation by accident, the inner
tube may be surrounded by a sheath of mill board, or pasteboard if desired.
The form of cable, the construction of which has now been described, may be laid
overground as well as underground, as, for instance, along the line of railways, and
in such case may be conducted across streams, ravines, and marshes, by the trestle-
work which supports the track and bridges. In laying this style of cable
overground I preferably arrange it in a housing, this housing being supported on
short posts, the height of which may vary in accordance with the topography of
the rout in order to keep the cable as nearly on a level as is found desirable. The
housing should have a proper transverse capacity to permit the cable to be
surrounded by an insulating material similar to that within it, the cable being
supported centrally within the housing by any suitable means preparatory to the
insulating material being placed around it. Suitable cross partitions might be
placed at intervals in the housing with apertures for the passage of the cable, the
insulating material being filled in between said partitions and the roof of said
housing, or one side of the roof afterwards placed in position.
While it is probably preferable to protect the overground cable by the housing,
substantially as described, it is not absolutely necessary as the cable may be
supported by suitable brackets or slings on posts, trestle work, or bridges, and painted
to protect the outer tube from the weather.
The cable either overground or underground being in readiness for use, a current
of hot water; steam, or hot air is to be forced through the inner tube, and will by
the heat which it imparts effectually dissipate all moisture, which is otherwise liable
to collect by condensation upon the wires and tubes, said wires and tubes being
always maintained in their relative positions and the wires properly insulated
owing to the non-susceptibility of the insulating material to chemical change, or to
be affected by variation of temperature.
The entire cable may have branches connected with it in any suitable manner,
as, for instance, a T-joint inserted in the inner tube, and a branch tube is connected
with said joint and leads through a neck projecting from the side of the outer tube.
To this neck a branch outer tube may be connected and constructed in the same
manner as described for the main cable.
In a modification of this cable I reverse the relative positions of the electrical
conductors and the heating medium. In this modification the sections of the outer
tubing are joined together in the same manner as in the form first described, but
the inner tube is relatively much larger than the inner tube of said first described
form, in order that it may have suflicient capacity to contain the properly separated
electrical conductors. The inner tube is composed of short lengths of either iron or
earthenware tubing having collars for forming joints in the ordinary manner, and
should be arranged to break joints with the outer tube, so that in constructing the
cable the end of the inner tube will project outward beyond the end of the last
laid section of the outer tube. This for convenience in filling in and ramming the
insulating material in the inner tube, this filling and ramming being performed

page_text: with obvious modifications of the apparatus heretofore described. The templets
for the inside of tube are simply discs of porcelain or other rigid insulating
material pierced with apertures for the passage of the wires. The inner tube is
supported centrally within the outer tube by means of open frames or spiders
'consisting of bands having lugs projecting outward therefrom, and of such length
as to permit said spiders or open frames to fit within the outer tube. A sufficient
number of these spiders and also of the templets must be passed over the wires at
the commencement of the construction, and in laying down the tube-sections for
use one of the smaller sections should be placed in each large section in order to
have them conveniently near each other when required.
The outer tube having an inner diameter of six inches, the inner tube may have
an external diameter of about four or five inches, the intervening space forming
the passage of the heating medium.
This modification of the cable may be laid overground as well as the form first
described, but more particularly requires to be protected by a housing and,
surrounding insulating material to prevent loss of heat by radiation, as in this case
the heating medium is next to the outer tube, while in the former case radiation is
almost entirely prevented by the packed talc which surrounds the inner tube.
The wires used in both the modifications of the cable may be naked, but I prefer
to have them provided with an insulating coating of cotton, kerite, or some other
approved insulator, before being embedded in the mineral in the tubes.
I may use a cable composed simply of a tube containing the conductors packed
in powdered tale or its equivalent without the heating tube, and without departing
from my Invention. Or I may arrange the wires or conductors without the
surrounding packed mineral in any suitable enclosure or passage way, and arrange
also in or adjacent to 'said passage way a conducting passage or tube for a heating
medium, as, for instance, the wires without the surrounding packed mineral may
be properly supported through a tunnel or covered trench or enclosed viaduct,
through which is arranged a pipe or passage for conducting a heating medium as
before described. Or I may suitably arrange the conductors in a tube and pass
through the same tube hot air.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said William Robert Lake in the Great Seal Patent Office on the
24th October 1881.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. "IMPROVEMENTS IN AND RELATING TO TELE-
GRAPHIC CABLES OR CONDUCTORS." A communication from abroad by Patrick
B. Delany, of the City and State of New York, United States of America,
Electrician.
The object of this Invention is to produce for use either underground or above
ground a telegraph-cable which will be practically unaffected by variations of
atmospheric or earth temperature, and in which the conductors will be protected:
from the effects of moisture and electrical induction.
Many attempts have been made to produce a cable of this character, but
experience has shewn them to be only partially successful. In some of these cables
the conducting wires have been enclosed in tubes and surrounded by a fusible
resinous insulating material, which is melted and forced into the tubes around the
wires. Such insulating material has been found to be easily affected by even
slight changes of temperature, and the tubes are in consequence warped and often
broken, and the wires brought in contact with each other or the tube, and thus
rendered useless as conductors. Moreover, most of such insulating materials
undergo chemical decomposition in a short time, and permit or promote the
condensation of moisture upon the wires. In other cables the protection and.
insulation of the wires depend upon fibrous vegetable insulators, which soon decay,
and in one form of cable the conductors are enclosed in a tube kept filled with oil,
which has been found to soon decompose and deleteriously affect the wires.
My Invention is designed to obviate these difficulties, and consists mainly in.
protecting the electrical conductors from moisture by conducting heat by means
of a suitable medium in sufficiently close proximity to the said conductors to
dissipate all moisture in their immediate vicinity and prevent its condensation
upon them.
My Invention further consists in a telegraph cable composed of a protecting-
tube, in which are stretched the conducting-wires surrounded by dry pulverized
tale. This substance is not liable to be affected by variations of atmospheric or
earth temperature, and therefore the cable will not be warped, twisted, or ruptured
by contractions and expansions of the insulating material. It is but slightly
liable to chemical change, and when properly packed remains well in that condition,
and is not liable to crumble or be injuriously affected by any thermic or hygro-
metric conditions which it is likely to encounter. Tale is plentiful and easily
accessible, there being extensive mines or veins of it in various parts of the world;
it is therefore cheap.
My Invention also consists in a telegraph cable composed of an outer and an
inner tube, forming two chambers, in one of which are arranged the electrical
conductors properly supported and insulated, while the other chamber serves as a
passage for a suitable heating medium, such as hot air, hot water, or steam, this
second part of my Invention being a practical application of the first part. Or
this telegraphic cable, composed of an outer and an inner tube, in some cases has
the electrical conductors arranged between the end tubes and packed in a suitable
insulating material, while the inner tube is left to serve as a passage for a heating
medium. This heating medium, while serving the other purposes hereinbefore
set forth, also by its action upon the insulating material causes this material to
have just sufficient electrical conductivity to relieve the wires of overstrain from
electrical currents, and prevent them in a great degree from affecting one another
by induction.

page_text: In the accompanying Drawings Figure 1 is a side view partly in section of a
portion of a telegraph-cable, constructed according to my Invention; Figure 2 is
a cross-section of the said cable; Figure 3 is a sectional side view of a portion of
the said cable; Figure 4 is a perspective view of a templet for supporting the wires
and inner tube of a cable constructed as shewn in the preceding Figures; Figure 5
is a sectional side view, and Figure 6 is a cross-sectional view of a modified form of
the said cable; Figure 7 shews an open frame or spider for supporting the inner
tube of a cable, constructed as shown in Figure 5; Figure 8 illustrates a mode of
connecting a branch cable with the form of cable illustrated in Figures 1, 2, and 3;.
Figure 9 illustrates the junction of a branch with the form of cable shown in
Figure 5.
Figure 10 is a perspective view illustrating a mode of laying above ground a
cable constructed according to my Invention.
Figure 11 is a side view of a portion of a cable in process of construction, and
shows an apparatus used for introducing the insulating material.
Figure 12 is a perspective view of an apparatus used in ramming the pulverized
tale material into the tube.
Figure 13 is a plan, partly in section, illustrating the mode of ramming the
insulating material into the tube..
Figure 14 is a perspective view of the follower.
Figure 15 shews the yoke for connecting the tube with the frame of the ramming
machine.
Figure 16 is a sectional view illustrating a cable similar to that shown in
Figure 1 but with the packed tale omitted.
Figure 17 is a longitudinal sectional view of the wires not surrounded by the
packed tale, and a heat-conducting tube arranged in a tunnel.
Figure 18 is a cross-section of the said tunnel.
Referring to Figure 1, A indicates an outer tube, which may be made of cast
iron or other suitable material, and in short lengths, connected by leaded joints
like ordinary gas-mains.
B is the inner tube, which may be also made of any suitable material which is
practically impervious to air and water, but for which by preference I use an iron
pipe in sections connected by suitable couplings, an inner tube of say one
inch diameter being placed in an outer tube of say six inches diameter. These
proportions may however be varied as desired.
C designates the conducting-wires, which are stretched in the space between the
inner and outer tubes.
D is the insulating material which surrounds the inner tube and the wires, and
is tightly packed between the two tubes by apparatus which will be hereinafter
described, or by other suitable means.
E. designates the templets which maintain the tubes and wires in their proper
relative positions, each of said templets being a disc of porcelain or other non-
conductor of electricity, of a diameter to fit and move snugly within the outer tube
and provided with a central aperture e for the passage of the inner tube, and a
surrounding series of apertures e¹ for the passage of the wires.
The various elements of the cable are manufactured or prepared in the usual
manner; but the cable as a whole composed of these elements is made as it is laid or
arranged for use and in substantially the manner described as follows, that is
to say
Supposing an underground cable is to be laid, a trench is dug of the desired
depth, say. two or three feet, and on the bottom of this trench are laid the lengths
or sections of the outer tube, these sections being separated from each other by a
suitable space for convenience in working, say for instance the sections are laid in
suitable number to form a mile of the cable, I then pass through all. these sections a
length of the iron pipe which is to form the inner tube. I then pass through all of
these sections a length of the iron pipe which is to form the inner tube. I then pass
through the said sections the predetermined number of wires which are to form the

page_text: electrical conductors. Ample space should be left at the initial end of the trench
for convenience in working, that is to say, about a rod should at first be left
vacant from the point where the cable is to begin. The inner tube and wires
having been passed through the outer tube sections, I draw these wires and tube
some distance beyond the initial section, and then string upon the said wires and
tube a sufficient number of the templets E, for use in the length or section of cable
to be presently constructed, that is to say, preferably one templet for each outer
tube-section, though more may be used if desired. The wires being passed
through coincident apertures in the templets, the initial section of the outer tube
is then moved along in the trench to the place it is to finally occupy, and all save
one of the templets which have been strung upon the wires and inner tube are
forced through the initial section of the outer tube and moved along the wires in
advance of the said section, so that they will not obstruct subsequent operations.
I then secure the wires and inner tube in any suitable manner, so that they cannot
be drawn through the apertures of the first templet, that is to say, the one which
has not been passed through the initial section of the outer tube, leaving a
sufficient length of the wires and inner tube projecting through said templet for
convenience in making connections. The said templet is then placed so as to close
the end of the initial outer tube section, and there secured by any suitable means,
for instance, by a suitable bar attached to its outer face, which will project radially
beyond the tube-wall; or this first templet may have a rim to fit against the end
edge of the tube.
I now have the parts arranged as partially shown in Figure 11, and one of the
templets which has been passed through should be moved up toward the mouth of
the initial outer tube-section, as shown in this Figure, this templet being supported
by a shoe fat a little distance from the mouth of the outer tube-section, to bring
its apertures in line with those of the templet in the opposite end of said tube-
section, in order that the wires and inner tube may be held straight. The initial
outer tube-section is then ready to receive the insulating material which is to be
packed within it, and surround the wires and inner tube respectively. This
insulating material being coarsely powdered, is to be blown in by the apparatus G,
(shown in Figure 11); G' is a case in which is mounted a fan operated by a
crank g, and from this case extends an eduction-tube g' at an intermediate point
in which is connected a hopper G2, while to the end of said eduction-tube is
connected a hose g². The end of this hose is introduced into the tube-section
nearly the full length of the same, and the powdered insulated material having
been previously heated to expel moisture is placed in the hopper; the fan is then
operated, and the said powdered material will be forced into the tube, the hose
being gradually withdrawn as the filling proceeds. When the tube-section has
been properly filled, say, to within three or four inches, or as near as practicable to
its mouth, the hose is entirely withdrawn, and the templet which has been placed
upon the shoe f is forced into the mouth of the section, and the said templet and
the isnulating material are then rammed in by means of the apparatus shewn in
Figures 12, 13, and 14, or by other suitable means.
Referring to the apparatus illustrated in these Figures, H designates a hollow
follower composed of two longitudinal semi-cylindrical sections h, h, provided with
flanges h¹ and ears h² which are held together by suitable bolts. This hollow
follower is placed around the wires and inner tube in advance of the tube section,
and its smaller end introduced into the mouth of the section and against the
margin of the templet, which is in front of the insulating material. In this position
the follower is ready to be operated upon by the ramming-machine shown in
Figure 12. This machine has a frame I adapted to sit upon the surface of the
ground, and provided with downwardly-projecting portions I' adapted to extend
down into the trench. On the inner sides of these downwardly projecting portions
are arranged the ramming-bars i moving in suitable guides ¹, and provided on
their outer surfaces with teeth which engage the worms / mounted on shafts ¹;
these shafts have fixed upon them worm-wheels Ɩ which engage with the worms l

page_text: on vertical shafts 12; these vertical shafts are provided with worm-wheels which
engage with worms on the motive shaft M provided with suitable cranks. The
machine is arranged by blocking or otherwise, so that the outer ends of the bars i
will bear against opposite sides of the head of the follower H, as shewn in Figure 13,
the follower-head being preferably provided with sockets to receive the ends of
the said bars. The yoke N (shown in Figure 15) is placed around the end of the
tube-section behind its collar, as shown, and connected with the frame of the
machine by the rods n; the machine is then operated by turning the cranks of the
shaft M, the bars i advancing and driving the follower H in until the insulating
material is packed as tightly. as desired. The ramming being completed 'the said
apparatus and its adjuncts are removed, an additional tube-section is moved up,
its end placed in the collar of the ramined section, and the joint leaded in the
ordinary manner, as shown in Figure 1. It is then filled and rammed in the same
manner as the first section, and the operation is repeated for all succeeding sections.
Any suitable apparatus may be used for filling and ramming the sections without
departing from my Invention.
In order to guard against interruption of the insulation by accident the inner
tube may be surrounded by a sheath of mill-board or paste-board if desired.
The cable whose construction has now been described may be laid above ground
as well as underground, as, for instance, along the line of a railway. In laying
this style of cable above ground I preferably arrange it in a housing 0, as shewn
in Figure 10, this housing being supported on short posts o, the height of which
may vary in accordance with the topography of the route in order to keep the
cable as nearly level as may be desirable. The housing O should have a proper
transverse capacity to permit the cable to be surrounded by an insulating material
similar to that within it, the cable being supported centrally within the housing
by any suitable means preparatory to the insulating material being placed around
it. Suitable cross-partitions might be placed at intervals in the housing with
apertures for the passage of the cable, the insulating material being filled in between
the said partitions and the roof of said housing, or one side of the roof afterward
placed in position.
Although it may be preferable to protect the overground cable by the housing,
substantially as described, it is not absolutely necessary, as the said cable may be
supported by suitable brackets or slings on posts, trestle-work, or bridges, and
painted to protect the outer tube from the weather.
The cable, either above ground or under ground, being in readiness for use, a
current of hot water, steam, or hot air is to be forced through the inner tube, and
will, by the heat which it imparts, effectually dissipate all moisture, which is
otherwise liable to collect by, condensation upon the wires and tubes, the said
wires and tubes being always maintained in their relative positions and the wires
properly insulated by reason of the non-susceptibility of the insulating material to
chemical change, or to be affected by variation of temperature.
The entire cable may have branches connected with it in any suitable manner,
as, for instance, as shown in Figure S, where B' indicates a T-joint inserted in the
inner tube, a branch tube B2 being connected with the said joint and extending
through a neck A¹ projecting from the side of the outer tube. To this neck a
branch outer tube may be connected and constructed in the same manner as
described for the main cable. To properly support the main inner tube at the
commencement of the construction of the branch cable templets should be placed
as shown in the main outer tube near each side of the junction of the branch, and
these templets, in conjunction with another, which is placed in the neck A¹, serve
to support the branching wires where they are bent to change their direction.
Ordinary T-joints may also be used for forming the junction of branches with
the outer tube, and two branches may lead in opposite directions from the main
cable if desired, the ordinary four-way joint being used in such cases.
In the modification illustrated in Figure 5 I reverse the relative positions of the
electrical conductors and the heating medium. In this modification the sections of

page_text: the outer tubing are joined in the same manner as shewn in Figure 1, but the
inner tube B2 is relatively much larger than the inner tube shown in this Figure
in order that it may have sufficient capacity to contain the properly separated
electrical conductors C2. The inner tube B2 is composed of short lengths of either
iron or earthenware tubing, having collars for forming joints in the ordinary
nanner, and should be arranged to break joint with the outer tube, so that in
constructing the cable the end of the inner tube will project outward beyond the
end of the last laid section of the outer tube. This is for convenience in filling in
and ramming the insulating material in the inner tube, this filling and ramming
being performed with obvious modifications of the apparatus heretofore described.
The templets for the inside of the tube B2 are discs of porcelain or other rigid
insulating material pierced with apertures for the passage of the wires. The
tube B is supported centrally within the outer tube A² by means of open frames
or spiders P, consisting of bands p having lugs pl projecting outward thereform,
and of such length as to permit the said spiders or open frames to fit within the
outer tube. A sufficient number of these spiders and of the templets must be
passed over the wires at the commencement of the construction, and in laying
down the tube-sections for use one of the smaller sections should be placed in each
large section in order that they may be conveniently near cach other when
required. The outer tube having an inner diameter of six inches, the inner tube
may have an external diameter of about four or five inches, the intervening space
forming the passage of the heating medium. This modified cable may be laid
above ground as well as that illustrated in Figure 1, but more particularly requires
to be protected by a housing and surrounding insulating material to prevent loss of
heat by radiation, as in this case the heating medium is next to the outer tube,
while in the former case radiation is almost entirely prevented by the packed
pulverized tale which surrounds the inner tube.
In Figure 9 is illustrated the mode of making a junction for a branch of cable
constructed according to Figure 5. T-joints are used in both pipes, and an
elongated templet E' with side passages for the branch wires is preferred.
The wires used in both modifications of the cable may be naked, but I prefer to
have them provided with an insulating coating of cotton, kerite, or other suitable
insulator before being imbedded in the mineral in the tubes. I do not confine
myself to any particular forms of joints or couplings.
By means of suitablo joints or junction-pieces branches may be extended to
the surface from underground pipes for establishing test-boxes at convenient
points.
The inner tube when metallic in both forms of the cable may be used as an
electrical conductor for sending either reversed or constant currents, which will
counteract the effect of induction between the wires, or it may be grounded at
such distances as may be found desirable for the purpose of destroying induction.
In Figure 1 g indicates wires connecting the inner and outer tubes, an arrange-
ment which is equivalent to grounding when the outer tube is in contact with the
ground, but in an over-ground cable the said wires should pass through the outer
tube to the ground.
I may use a cable composed simply of a tube containing the conductors
packed in powdered talc without the heating-tube, or I may arrange the wires
or conductors without the surrounding packed mineral in any suitable inclosure
or passage-way, and may arrange in or adjacent to the said passage-way a con-
ducting passage or tube for a heating medium; for instance, the wires, without
the surrounding packed mineral, may be supported through a tunnel or covered
trench or enclosed viaduct, through which is arranged a pipe or passage for
conducting a heating medium. In Figures 17 and 18 R indicates the wall of
the tunnel, C³ the conducting wires, and B' a tube or pipe for conducting hot air,
hot water, or steam.
A cable may be constructed, as shown in either Figures 1 or 5, without the
packed mineral, in which case the wires properly insulated will be surrounded by

page_text: hot air in direct contact with them. This form is shewn in Figure 16 of the
Drawings.
Having thus fully described the said Invention as communicated to me by my
foreign correspondent, and the manner of performing the same, I wish it understood
that I am aware that powdered glass, silicious stones, and asbestos have been used
to pack tubular telegraph-cables, but powdered glass and stones are good conductors
of heat, and would permit radiation very disadvantageous to my heated cable,
while asbestos will not remain in a packed condition except under continuous
pressure, I therefore do not claim any use or application of these substances for the
purpose of my Invention, but I claim,-
First. The method herein described of protecting electrical conductors from
moisture, which method consists in conducting heat by means of a suitable medium
in proximity to the said conductors, whereby moisture will be dissipated in the
neighbourhood of and prevented from condensing upon the said conductors, sub-
stantially as described.
Second. A telegraph-cable composed of a protecting-tube, in which are arranged
the conducting-wires closely surrounded by pulverized talc, which is packed
within the said tube and closely around the said wires, for the purpose specified.
Third. A telegraph-cable composed of an inner and an outer tube forming two
chambers, one of said chambers containing the conducting wires packed in a
suitable insulating material, and the other being left vacant to serve as a conductor
for a heating medium, substantially as described.
In witness whereof, I, the said William Robert Lake, have hereunto set my
hand and seal, this Twenty fourth day of October, in the year of our
Lord One thousand eight hundred and eighty one.