IMPROVEMENTS IN THE INSULATION OF SUBTERRANEAN. ELECTRIC TELEGRAPH WIRES, AND IN LAYING THE SAME
Year: 1867

page_text: LETTERS PATENT to Thomas Beaumont Marshall, of Queen Street;.
Cheapside, in the City of London, for the Invention of "IMPROVEMENTS IN
THE INSULATION OF SUBTERRANEAN. ELECTRIC TELEGRAPH WIRES, AND IN
LAYING THE SAME."
Sealed the 4th October 1867, and dated the 5th April 1867..
PROVISIONAL SPECIFICATION left by the said Thomas Beaumont Marshall
at the Office of the Commissioners of Patents, with his Petition, on
the 5th April 1867.
I, THOMAS BEAUMONT MARSHALL, of Queen Street, Cheapside, in the City
of London, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN THE INSULATION OF SUBTERRANEAN ELECTRIC TELEGRAPH WIRES, AND IN
LAYING THE SAME," to be as follows:-
I propose to insulate the wire or wires when the channel or tube intended
to contain it or them is in or near the position or place where it is intended.
to remain. According to the number of wires I have to insulate the size of
the channel or tube should be greater or less; say, if I have 20 wires to
insulate, then I commence with half an inch, more or less, in depth as a layer
of the insulating matter or medium applied in a fluid state, and when-
sufficiently cool I place 2 wires parallel on the cool insulating material or
matter; then I add another half an inch, more or less, of the insulating matter

page_text: or medium, and so on until the whole of the wires are insulated, leaving always
about the same thickness of the matter between each wire and the material
in which it is contained or enclosed. The channel or tube may be formed
either of any metallic or non-metallic substance.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Thomas Beaumont Marshall in the Great Seal Patent Office
on the 5th October 1867.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
BEAUMONT MARSHALL, of Queen Street, Cheapside, in the City of London,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fifth day of April, in the year of our Lord One
thousand eight hundred and sixty-seven, in the thirtieth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
Thomas Beaumont Marshall, Her special licence that I, the said Thomas
Beaumont Marshall, my executors, administrators, and assigns, or such others
as I, the said Thomas Beaumont Marshall, 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 THE INSULATION OF SUBTERRANEAN ELECTRIC
TELEGRAPH WIRES, AND IN LAYING THE SAME," upon the condition (amongst
others) that I, the said Thomas Beaumont Marshall, my executors or adminis-
trators, 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 Thomas Beaumont Marshall, do hereby
declare the nature of my said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and by the
following statement :-
My Invention consists of certain improvements in the means of insulating
telegraph wires for subterranean use, and in laying the
same, the object being

page_text: to enable long wires of telegraphs to be laid down very rapidly and at a
moderate expense in comparison with other methods hitherto proposed or
adopted. I propose to insulate the wire or wires when the channel or tube
intended to contain it or them is in or near the position or place where it is
intended to remain. According to the number of wires I require to insulate
the size of the channel or tube should be greater or less; for example, if 20
wires are to be insulated, then I commence with half an inch, more or less, in
depth as a layer of the insulating material or compound applied in a plastir,
soft, or fluid state, and when sufficiently cool, set, or hard I place two or more
wires parallel on the cool insulating material or compound; then I add another
half an inch, more or less, of the insulating material, and so on until the whole
of the wires are insulated, leaving always about the same thickness of the
material or compound between and on all sides of each wire. The channel
or tube may be formed either of any metallic or non-metallic substance.
I am aware that it has already been proposed to place telegraph wires when
insulated in tubes or channels filled with insulating materials or compounds,
for the purpose of rendering the insulation more complete, or securing the
wires and their original insulation from the effects of moisture, and that such
lines are capable of being laid in trenches without further manipulation; but
my Invention consists in laying bare wires along trenches in which are placed
channels or tubes containing insulating material or compound, and enclosing
them therein (or such material or compound may be placed in or on the
ground with or without any other foundation), and by so doing insulating the
wires in or near the position or place where they are intended to remain.
Also, my Invention consists in laying wires, when either bare or insulated
wholly or partly, by extending them upon a layer of insulating material or
compound when sufficiently hard for the wires to rest upon it without sinking
below the surface, and then covering over with a further quantity of insulating
material or compound, and in laying a further series of wires on such compound
or material, as may be desired. The insulating substance being placed in a
trench or upon the surface of the ground, either alone or in a channel formed
by consecutive metallic or non-metallic gutters, the wires being laid by means
of a travelling carriage containing reels or drums from which the wires are
unwound and laid on the insulating material in any lengths required. The
trench (when such is used) should be opened as evenly and straight as possible.
(consistent with the undulations of the ground) and of the required length,
depth, and width; the length will of course be that of the line to be placed
underground, and the depth and width will be governed by what may be found
necessary for the convenience of the work and so that the line may be kept

page_text: out of the reach of ordinary casualtics or damage hereafter. A channel,
foundation, or receptacle for the insulating material, either containing the first
layer of it in the first instance or to be supplied afterwards, is to be placed
at the bottom of or close to the trench, (in cases where it might be more
convenient to work at a higher level than the bottom of the trench the channels
or foundations may be laid upon a raised platform directly communicating with
it, and after the wires are laid the portions of the work, as they become
completed, may be lowered to the bottom of the trench), with or without any
other foundation, and the first layer of insulating material, if not already
there, must be laid to the required depth or thickness, and allowed to remain
undisturbed until sufficiently cool or hard. The first layer or row of wires must
now be set in their proper places and at the required distances apart, and made
fast to the beginning of the work, and as soon as the insulating material is
sufficiently hard, so that the wires will not sink into it below the surface, at
any rate more than merely to indent the surface, they must be placed upon it
and uncoiled in parallel lines from the reels or drums or whatever holds them,
and when extended to a convenient distance must be drawn sufficiently tight
to prevent them from moving about so much during the process as to endanger
their coming in contact. A guage must then be introduced capable of sliding
down the wires and keeping them at the proper distances apart as the work
proceeds. The wires must then be fastened down at suitable distances so as
to fasten them to the under layer of insulating material; this I effect by
setting at the points selected the sliding guage, near to which a quantity of
insulating material is to be applied, so as to cover the wires and secure them
in their proper places as determined by the guage; these sealings or fastenings
should extend for a sufficient length on the wires so as to secure them in their
proper places, and should be at such distances apart as may be found
necessary for keeping the wires parallel and firmly in their places. The
spaces between the sealings, as soon as they have become firm or hard
enough to hold the wires, may be filled in with insulating material to the
required depth or thickness. The second and further series of wires (if
such are required) must be treated in exactly the same manner as the first
row; the same process must be gone through of guaging the wires and sealing
them down until the required number of wires have been insulated or enclosed;
after which a series of caps, plates, or other covering may be placed over the
line so as to further protect it from accidental injury; the trench is then to be
filled up and the work will be complete. The channels or tubes may be formed
of any shape, either square, tubular, or angular, and of any size and length that
may be found convenient; also of any material, such as iron or other metal,

page_text: or of pottery ware, or wood, the sole condition being moderate straightness
and capacity for containing the required quantity of wires and insulating
material; or a channel may be formed upon a flat surface answering the
purpose of a foundation by the use of the guages, which may also be used
upon a foundation already in the trench. In using or applying the guages, if
the bottom of the trench is sufficiently level and dry, there will be no occasion
for any other foundation, but a foundation would probably be found convenient
in most cases; almost any substances would answer the purpose, provided they
could be laid tolerably straight and even; for example, a bed of concrete, a
line of slates, a row of bricks laid end to end, a series of narrow planks, or a
strip of manufactured fabric. The guages, which while in use perform a
similar requirement to that of the sides of a permanent receptacle, by holding
in the soft, molten, or liquid insulating material laterally until it becomes set
or sufficiently hard to keep its position, must be placed eveuly along the
foundation, and the space between them filled up with insulating material to
the requisite depth. The insulating material or compound must consist of
some substance or combination of substances or materials which are good
non-conductors of electricity, and such as can be used in a plastic or soft or
fluid state, and become when set or cold sufficiently, bard to prevent the wires
from sinking below the surface. It is also essential that the perfect junction
of the successive layers be effected by adhesion, otherwise moisture will in
time penetrate between the layers of material and reach the wires, thus
causing a diminution of the electric current by contact with the earth. In
the use of asphalte or pitch in their several varieties, and their compounds, a
perfect junction will be ensured, provided the fresh layer is poured on to the
one already formed in a sufficiently beated state, in order that the surface of
the cold material beneath may be thereby raised in temperature to the point
of fusion, so as to cause adhesion or union of the two layers. It must be
understood that this system is applicable to other insulating materials besides
asphalte and pitch, or compounds in which either of these substances in their
several varieties form an ingredient, as any material or compound that is a good
non-conductor of electricity and capable of being used in the manner herein
described may be employed, whether or not heat is a necessary agent in its
preparation and application. The number of wires to be laid in each row
must be determined by circumstances. All the wires to be insulated may be
laid in one row if desirable, in which case two layers of insulating material
only will be required, viz., one as a foundation for the wires and the other as
a covering, or successive rows may be laid consisting of the same or a greater
or less number of wires; the shape of the channel and the nature and size of

page_text: the protective covering selected will chiefly affect the question, and where
economy in space is an object, the distances between the wires must be
diminished accordingly. This will, however, necessitate greater care in the
work, but with sufficient attention to the details described herein and the use
of a good insulating material or compound, the wires may be laid almost close
to each other.
In the accompanying Drawings Fig. 1 represents a plan view of the guage
for laying and controlling the insulating materials or compound on a foundation
or on the surface of the ground or the bottom of a trench, and Fig. 2 is a
perspective elevation of the same. a, a, are the sides of the guage, which are
connected together by the regulating straps b, b, or they may be held together
by other suitable means, such as by pins or studs set in the guages in place of
the straps, such pins or studs being secured by perforated cross bars, by which
means the guages are kept at a constant distance apart.
Fig. 3 represents a plan view of a channel or foundation with insulating
material or compound c, c, therein; d, d, are the wires proceeding from the
reels or drums e, e, on the carriage or truck; f represents a junction of two
channels; and 9, 9, the sealings on the wires; is the position of the sliding
guage, which is shewn separately in Fig. 4, where the wires d, d, pass through
narrow slots in the sliding guage, and then descend at a slight angle along the
sloping ends of the guage, being pressed down on the insulating layer by tho
roller attached to the rear of the guage.
Figs. 5, 6, 7, and 8 shew respectively a square section of channel or insu-
lating material or compound, an oblong section for one layer of wires, a
semitubular section with cap or cover, and an angular section; d, d, are the
sections of wires.
Having now described the nature of my said Invention, and the manner in
which the same is to be carried into practical effect, I claim,―
1st, the insulation or enclosing within insulating material or compound of
metallic wires intended for subterranean electric telegraph use by means of
sections, that is to say, by extending them upon a layer of insulating matter
when sufficiently hard for the wires to rest upon it without sinking below the
surface, and then covering over with a further quantity of insulating material
or compound; and if desired, for the purpose of enclosing more wires, repeating
the operation, that is, adding alternately in the same manner lines or rows of
wires and layers of insulating material.
2nd, the insulation of metallic wires intended for subterranean electric
telegraph use by enclosing them bare (that is to say, not previously insulated,
either wholly or in part,) when in or near the position or place where they are

page_text: intended to remain in any insulating substance or compound placed in a channel
or tube, or in such substance or compound first laid in the trench or on the
ground with or without any other foundation.
3rd, the insulation or enclosing within insulating materials or compound of
metallic wires for the purpose specified, either bare or insulated previously,
wholly or in part, when in or near the position or place where they are intended
to remain, and either in channels or tubes, or without their use by means of
sections, all substantially as herein specified and partly shewn by the Drawings
aunexed.
In witness whereof, I, the said Thomas Beaumont Marshall, have hereunto
set my hand and seal, this Second day of October, in the year of our
Lord One thousand eight hundred and sixty-seven.
Witness,
ALEX. M. PRINCE,
Office for Patents,
4, Trafalgar Square,
Charing Cross,
T. B. MARSHALL. (L.S.)