Improved Underground Conduit System for Electrical Distribution.
Year: 1890

page_text: Date of Application, 11th July, 1890
Complete 'pecification Left, 7th Apr., 1891-Accepted, 9th May, 1891
PROVISIONAL SPECIFICATION.
Improved Underground Conduit System for Electrical Distribution.
I, BENJAMIN JOSEPH BARNARD MILLS, of 23 Southampton Buildings, in the
County of Middlesex, Patent Agent, do hereby declare the nature of this inven-
tion, a communication to me from abroad by Edwin Trueman Greenfield, of the
City, County and State of New York, in the United States of America, Manufacturer,
to be as follows:-
This invention relates to a new and improved system of underground electrical
distribution wherein are employed a casing or conduit for the electrical conductors:
manholes laid at suitable distances apart for the purpose of obtaining access to,
laying, and connecting the conductors located within the conduits; handholes
interspersed in the length of the conduit for the purpose of aiding or assisting the
laying of the wire; and junction boxes, such that leads may be connected with the
mains without disturbing the main casing or conduit.
The object of the invention is a conduit system which shall be easily and cheaply
laid, which shall be durable, dry, free from danger of explosion from gas, easily
accessible at desired points and affording high insulation to the naked electrical
conductors which it is proposed to use.
The casing or conduit for the electrical conductors is laid in sections; each
section includes a trough, preferably rectangular in cross section, formed preferably
of wood treated with a water proofing and preserving material. Within this trough
the wire ways are formed. These wire ways are formed of compound tubes
possessing high insulating properties. Each of these tubes is made by combining
a formed base of animal, vegetable, or mineral porous, fibrous material, with a
filling of a bituminous compound, in such manner that the basis and filling material
become a homogeneous tube, which will be dense and hard and possess high
insulating properties and be unaffected by ordinary thermal or hygrometric
changes. To produce this compound tube it is preferred to take animal or
vegetable paper of an open porous structure, such as ordinary felt paper and form
it in the desired tubular shape. This formed base is combined with the filling
material, which preferably is black petroleum pitch, by immersing the formed base
in the filling material or compound a number of times, the filler being maintained in
a liquid state by heat, and allowing a period of rest between each immersion. The
resulting compound tube is superior to all tubes heretofore used as conduits for
electrical conductors in economy of first cost, durability, insulating and water-
proofing qualities.
The tubes are introduced in the trough above mentioned, and are held at
certain distances apart, so as to leave a free space around each tube.
Prefer-
ably they are held apart by upright and cross pieces which may be of insulating
material. The upright pieces being inserted in holes bored in the bottom
board of the trough, the cross pieces being slipped in opposite grooves in the side
walls of the trough.
When tubes are arranged in the trough as described, an insulating material,
hard when cold, is poured in a liquid state into the trough, so that it will have
free access to, and completely surround, each tube, thereby ensuring that the
conduit shall possess high insulating and water proofing properties. Ordinary
pitch may be used as the insulating material for encasing the tubes.
The manholes which it is preferred to use I term "double-jacketed" meaning
thereby provided with inner and outer walls, between which a sealing material is
located, the purpose being to prevent the penetration of moisture or gases to the
well of the manhole. This sealing medium may be a permanent liquid seal, or a

page_text: seal formed by a compound or material which is hard when cold. When a per-
imanent liquid seal is used, care of course will have to be observed to secure
tight joints between the portions of the manhole: preferably the man hole is
formed in sections for facility of combining with the conduits. The lower section
of the manhole is adapted to be erected in place, the conduits entered into the
same and the upper section of manhole, which preferably has depending flanges, is
located so that the flanges close the joint made between the upper and lower
sections. The upper section is provided with a seat which receives the street
cover, and also a seat for the inner cover.
At the point where the conduit enters the manhole, a double seal is provided by
arranging around the trough of the conduit a flange, which preferably is so
arranged with reference to the walls of the manhole that the flange is about mid-
way between the same; therefore when the sealing material is poured into the
space between the walls of the manhole, the flange becomes encased and forms a
double seal at a point where moisture and gas are likely to enter.
The outer cover of the manhole is of the ordinary type and arranged on its seat,
so as to be on about a level with the street. The inner cover is formed of two
discs of spring metal supported by a rigid annulus, one of the discs being provided
with a stop cock for the purpose of forcing between the discs a liquid under
pressure, whereby the discs are distended and the lower disc forced to its seat in
the manhole, which is preferably provided with a packing substance or material.
The molten insulating compound is filled in between the walls of the conduit
preferably through elongated bolt holes in the seat of the inner cover. These bolt'
holes receive the attaching bolts for the inner cover, said bolts being provided
below the elongated hole in the cover seat with elongated heads, which when turned
at an angle to the bolt hole, hold the cover firmly to its seat under the expanding
action of the liquid under pressure.
Where the conductor is to be led out of the manhole at an angle to the line of its
entrance, the tubes enter a box in the manhole, the tubes within the box being
provided with a permanent liquid insulating material, instead of with an insulating
material which is hard when cold.
Where a branch is taken from any of the conductors, the duct containing the
main has interposed in its length, a small oblong box preferably provided with
nipples projecting outward from its end walls, into which nipples the duct is led
and cemented, so as to form a water tight joint. The main conductor passes
through the box without any tubular covering, and the branch is connected with
it and taken off through a duct arranged with relation to the box similarly to the
main line duct. After the connection is made an insulating material adapted to
harden when cold is poured into the box in a liquid condition, a cover being placed
over the box if desired.
At manholes where the conduit is not carried through, a protection is provided
for the conductors comprising preferably split sleeves of an insulating material,
such as paper impregnated with pitch, which split sleeves are applied over the con-
· ductor so as to cover the same. Two short sections of tube previously slipped on
the conductor are brought together so as to cover the joints of the split sleeve.
Another short section of tube also previously slipped on the conductor, is now
brought in place, so as to cover the joint between the two short sections last men-
tioned. An insulating material is then poured over the whole so as to effectually
seal the joints.
The handhole which it is preferred to use is in all its essential features the same
as the manhole above described except that it is smaller, it being like the manhole
"double-jacketed" and having also an expansible cover and preferably a double
seal where the conduits pass through it.
Where it is anticipated that a future connection is likely to be made for
entrance into a house or other place, I divide the main wire way tube to be tapped
and secure at each divided end, a bend preferably of the same material as the tube
itself. These two bends bend outward and toward each other and are connected

page_text: by a third detachable bend, which completes a regular curve, through which the
conductor may be freely drawn. These bends are located in an offset box pro-
jecting laterally from the conduit and are surrounded therein by an insulating
material or compound. When it is desired to make a connection it is only necessary
to remove the cover from the box and the material from around the third or
joining bend, remove the latter, and connect the two remaining bends each with a
tube of insulating material, one for the ingoing wire and the other for the out
coming wire, it being understood that the wires are conveyed to and from the house
in insulating conduits.
1000
COMPLETE SPECIFICATION.
Improved Underground Conduit System for Electrical Distribution.
I BENJAMIN JOSEPH BARNARD MILLS of 23 Southampton Buildings in the
County of Middlesex Patent Agent do hereby declare the nature of this invention,
a communication to me from abroad by Edwin Trueman Greenfield of the City
County and State of New York in the United States of America Manufacturer,
and in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
This invention relates to a new and improved system of underground electrical
distribution wherein are employed a casing or conduit for the electrical conductors;
manholes laid at suitable distances apart for the purpose of obtaining access, to
laying and connecting the conductors located- within the conduits; hand holes,
interspersed in the length of the conduit for the purpose of aiding or assisting the
laying of the wire; and junction boxes, such that leads may be connected with the
mains without disturbing the main casing or conduit.
1
The object of the invention is a conduit system which shall be easily and
cheaply laid, which shall be durable, dry, free from danger of explosion from gas,
easily accessible at desired points and affording high insulation to the naked.
electrical conductors which it is proposed to use.
The casing or conduit for the electrical conductors is laid in sections; each
section includes a trough preferably rectangular in cross section, formed preferably
of wood treated with a waterproofing and preserving material. Within this trough
the wire-ways are formed. These wireways are formed of compound tubes
possessing high insulating properties. Each of these tubes is made by combining
a formed base of animal, vegetable or mineral porous, fibrous material, with a
filling of a bituminous compound, in such manner that the basis and filling material
become a homogeneous tube, which will be dense and hard and possess high
insulating properties and be unaffected by ordinary thermal or hygrometric changes.
To produce this compound tube, it is preferred to take animal or vegetable paper of
an open porous structure, such as ordinary felt paper and form it in the desired
tubular shape. This formed base is combined with the filling material, which
preferably is black petroleum pitch, by immersing the formed base in the filling
material or compound a number of times, the filler being maintained in a liquid
state by heat, and allowing a period of rest between each inmersion. The resulting
compound tube is superior to all tubes heretofore used as conduits for electrical
couductors in economy of first cost, durability, insulating and water-proofing
qualities.
The tubes are introduced in the trough above mentioned, and are held at certain
distances apart so as to leave a free space around each tube. Preferably they are
held apart by upright and cross pieces which may be of insulating material. The

page_text: upright pieces being inserted in holes bored in the bottom board of the trough, the
cross pieces being slipped in opposite grooves in the side walls of the trough.
When tubes are arranged in the trough as described, an insulating material, hard
when cold, is poured in a liquid state into the trough so that it will have free access
to and completely surround each tube, thereby ensuring that the conduit shall
possess high insulating and water proofing properties. Ordinary pitch may be
used as the insulating material for encasing the tubes.
The manholes which it is preferred to use I term "double jacketed," meaning
thereby provided with inner and outer walls between which a sealing material is
located, the purpose being to prevent the penetration of moisture or gases to the
vell of the manhole. This sealing medium may be a permanent liquid seal, or a
seal formed by a compound or material which is hard when cold. When a per-
manent liquid seal is used, care of course will have to be observed to secure tight
joints between the portions of the manhole; preferably the manhole is formed in
sections for facility of combining with the conduits.
The lower section of the manhole is adapted to be erected in place, the conduits
entered into the same and the upper section of manhole, which preferably has
depending flanges, is located so that the flanges close the joint made between the
upper and lower sections. The upper section is provided with a seat which receives
the street cover and also a seat for the inner cover.
At the point where the conduit enters the manhole a double seal is provided by
arranging around the trough of the conduit a flange which preferably is so arranged
with reference to the walls of the manhole that the flange is about midway between
the same; therefore when the sealing material is poured into the space between
the walls of the manhole the flange becomes encased and forms a double seal at a
point where moisture and gas are likely to enter.
The outer cover of the manhole is of the ordinary type and arranged on its seat
so as to be on about a level with the street. The inner cover is formed of two discs
of spring metal supported by a rigid annulus, one of the discs being provided with
a stop cock for the purpose of forcing between the discs a liquid under pressure
whereby the discs are distended and the lower disc forced to its seat in the manhole
which is preferably provided with a packing substance or material.
These
The molten insulating compound is filled in between the walls of the conduit
preferably through elongated bolt holes in the seat of the inner cover.
bolt holes receive the attaching bolts for the inner cover, said bolts being provided
below the elongated hole in the cover seat with elongated heads which when turned
at an angle to the bolt hole hold the cover firmly to its sent under the expanding
action of the liquid under pressure.
Where the conductor is to be led out of the manhole at an angle to the line of its
entrance the tubes enter a box in the manhole, the tubes within the box being pro-
vided with a permanent liquid insulating material instead of with an insulating
material which is hard when cold.
Where a branch is taken from any of the conductors the duct containing the
main has interposed in its length a small oblong box preferably provided with
nipples projecting outward from its end walls into which nipples the duct is led and
cemented so as to form a water tight joint. The main conductor passes through the
box without any tubular covering and the branch is connected with it and taken off
through a duct, arranged with relation to the box, similarly to the main line
duct.
After the connection is made an insulating material adapted to harden when cold
is poured into the box in a liquid condition a cover being placed over the box if
desired.
At manholes where the conduit is not carried through a protection is provided
for the conductors comprising preferably split sleeves of an insulating material, such
as paper impregnated with pitch, which split sleeves are applied over the conductor
so as to cover the same. Two short sections of tube previously slipped on the con-
ductor are brought together so as to cover the joints of the split sleeves. Another

page_text: short section of tube also previously slipped on the conductor, is now brought in
place so as to cover the joint between the two short sections last mentioned. An
insulating material is then poured over the whole so as to effectually se:l the
joints.
The hand hole which it is preferred to use is in all its essential features the same
as the manhole above described except that it is smaller it being like the manhole
"double jacketed" and having also an expansible cover and preferably a double
seal where the conduits pass through it.
Where it is anticipated that a future connection is likely to be made for entrance
into a house or other place, I divide the main wire-way tube to be tapped, and
secure at each divided end a bend preferably of the same material as the tube
itself. These two bends bend outward and toward each other and are connected
by a third detachable bend which completes a regular curve through which the
conductor may be freely drawn. These bends are located in an offset box pro-
jecting laterally from the conduit and are surrounded therein by an insulating
material or compound. When it is desired to make a connection it is only neces-
sary to remove the cover from the box and the material from around the third or
joining bend, remove the latter and connect the two remaining bends each with a
tube of insulating material, one for the ingoing wire and the other for the out-
coming wire, it being understood that the wires are conveyed to and from the
house in insulating conduits.
In the accompanying drawings, forming a part of this Specification,
Figure 1 is a diagram showing the arrangement of my underground system.
Figure 2 is a perspective view of a conduit, showing the flange which extends
between the two walls of the man hole, or hand hole, to effect the double seal.
Figure 3 is a cross section of the man hole employed in my system, showing
some of the wire ways carried out of the man hole at right angles to their line of
entrance.
Figure 4 is a plan view of the arrangement of conduits referred to as being
shown in Figure 3, being taken with the upper section of the man hole removed.
Figure 5 is a top plan view of the bottom part of the man hole, having a single
conduit passing therethrough, and showing also the method of encasing the con-
ductors between the end of two sections of conduit.
Figure 6 is a vertical section taken on the plane of the line 7-7 of Figure 3.
Figure 7 is a vertical section of a hand hole.
Figure 8 is a plan view of the house junction box employed for taking off leads
for houses, with the cover removed.
Figure 9 is a junction box for connecting a branch with the main.
In the drawings, A is the conduit, B the man hole, C the hand hole, and D the
junction box for house connections.
The conduit A has an outer casing of wood or other material E, treated with a
preserving and water proofing compound. This casing is laid in sections of any
length, the bottom and the two uprights thereof forming a trough, the cover being
applied after completion of the conduit. Near each end of the sections of the
trough, holes are bored to receive uprights F, one upright being arranged next
each upright wall of the trough, and other smaller uprights being arranged between
each of the tubes G, which form the wire ways of the system. Grooves H are
formed longitudinally in the side walls of the trough for the reception of cross
tubes I arranged so as to be interposed between the tubes G in the bottom of the
trough and between each tier of tubes. This arrangement of uprights and cross
supports holds the tubes away from the walls of the trough and from one another,
so that when the insulating material is poured about them it may have free access
and completely surround each tube. The uprights F and cross supports I are
preferably made of compound tubing which is inexpensive to use and may be
quickly cut to the desired lengths. After the wire way tubes G are properly laid
in the trough, the insulating material is poured therein and surrounds each tube

page_text: completely, and when it has become hardened the cover of the trough is secured in
place. A conduit constructed as above described possesses superior insulating
qualities, as the wire ways themselves are of insulating material and are further
inclosed in insulating material. They are also dry, as no moisture can penetrate
to the wire ways by reason of the thorough protection afforded by the outer casing
of treated wood or other material, the inner case surrounding the wire ways and
the wire ways themselves all being water proofing materials. Consequently by
reason of the high insulation and dry condition of the wire ways, it is possible to
employ naked conductors, due provision being made where the conduit is tapped
for leads or provided with man holes or hand holes to prevent moisture entering at
these points.
The
The man hole is formed in sections for facility of combining with the conduits.
The lower section J comprises an outer wall K and a bottom K¹ formed of wood or
other material preferably treated with a water proofing compound of coating, and
an inner wall L having a bottom L' preferably of the same material.
bottom L' is held above the bottom K¹ by legs M preferably at a distance there-
from about equal to the distance between the walls K and L. This lower section .J
of the man hole is laid in the ground and the conduit enters the same through the
openings N. Where a conductor is to be led out of a man hole at right angles to
the line of entrance, the conduits are arranged in the man hole as shown in
Figure 4 passing through openings N at right angles to the openings N. A
box a shown in plan Figure 4, is arranged within the man hole and into this box
the conduits are carried, the hardened insulating material ending at a as indicated
in the drawings. This leaves the tubes G and bends bared for a
portion of their
length within the box a. This is desirable for facilitating connections and laying
of wires. But to protect wire way the tubes from all danger from moisture, a fluid
insulating material is poured into the box a so as to surround the bare tubes G and
protect the same.
Where a branch is taken from any of the conductors the duct containing the
main has interposed in its length, a small oblong box , shown in Figure 9 of
the drawing. This box it will be seen is provided at each end and at one side with
nipples c projecting outward from the walls thereof. Into these nipples the ducts
are led and cemented, so as to form watertight joints therewith. The main con-
ductor passes through the box and the branch is connected to it as shown in the
drawing. After the branch connection is made, insulating material similar to that
used to encase the tubes G is poured in and allowed to harden, a cover being
placed over the whole if desired. The conduit, where it passes through the
openings N and N', is preferably provided, about mid-way between the walls of
the man hole, with the flange O extending all the way around the outer casing of
the conduit, so as to raise the same from the bottom K' of the man hole. The
upper section of the conduit may be formed of cast iron or other suitable material,
and comprises an outer wall P and an inner wall Q held together by boits or
otherwise. Both the walls P and Q are so arranged that they sit directly upon
the walls K and L of the lower section and have depending flanges P and Q
extending down to the conduit, whereby the joint is more effectually protected
from the entrance of moisture or gases. The upper portion of the upper section
of the man hole is provided with a seat R which receives the street cover S.
Between the walls P and Q, at their upper end, a seat is afforded for the inner
cover T. This inner cover T is formed of two spring metal discs T', T³, brazed
or otherwise secured to an annulus U of cast metal. This annulus Ú has a
number of bolts U₁, which are provided with an oblong head U2, the bolt holes in
the annulus being oblong, as are also the holes in the seat for the cover T as shown
at U. The plate T of the cover is provided with a cock T³ through which fluid
under pressure is forced into the space between the plates T and T. When the
conduits have been properly laid in the lower section of the man hole and the upper
section has been set in place, the sealing material is poured in through the

page_text: elongated openings Us in the seat for the cover T. This sealing material, which
may be oil or pitch, flowing as it does all around the conduit between the walls K
and L on each side of the flange O projecting from the conduit, effectually
prevents the entrance of gases or moisture at the points of junction of the conduit
and man hole and also through the wall of the man hole. When a permanent fluid
seal is used care must of course be taken to calk all joints, so that there is no
escape of liquid. After the insulating material has been introduced, the cover T
will be dropped in place, the bolts being turned so that their elongated heads will
pass through the elongated slots T3. The bolts are then turned at right angles to
their first position. Liquid or fluid under pressure is then forced through the
cock Ts between the plates T1 and T2 of the cover, until the plates of the cover
assume the position shown in dotted lines in Figure 3, a ledge T₁ being provided
in the inner wall Q of the man hole with which the distended plate T makes a
close contact, a suitable packing T being provided. The distention of the plates T¹
and T2 tightens the bolts U. The outer cover S is then set in place.
It will be seen from this description that the man hole is not only sealed at the
point of junction of the conduits with it, but also that it is sealed at its mouth so
that no moisture or gases penetrate into the working space thereof.
In Figure 5 have shown the method I prefer for protecting the conductors in
the man holes where the conduit has not been carried completely through the man
hole. In that figure, a is a conductor. bbare split sleeves preferably semi-
circular, made of paper impregnated with insulating material. These split sleeves
are applied over the conductor as shown in the second wire way to the right in
Figure 5. Over these split sleeves two short sections of tube c are drawn as
shown in the third tube to the right of Figure 5, and over the joint formed by the
tubes c. c, a short tube d is drawn. The tube sections c, c effectually close the
joints made between the sections b. and the joint formed by the abutting
sections c. c is itself closed by the tube d. Over the whole is then poured an
insulating material so as to effectually seal all the joints. In Figure 8 the hand hole
is shown. This hand hole need not be specifically described as it is in all its
essential features substantially the same as the man hole except that it is smaller.
In Figure 8 is shown the method of laying the conduit at places where it is antici-
pated that a future connection is likely to be made. As will be seen, the main wire
way is divided, and at each end of the division a bend e is secured. These two
bends are connected by a third bend f, so that the main wire may be drawn
through the wire way without greatly increased construction. This series of bends
is incased in a box g, which is provided with a suitable cover, insulating material
being poured about the wire ways as is done with the conduit. When it is desired
g
to make a connection all that is necessary is to remove the cover from the box
and cut away the material from around the bend f so as to remove the same, and
apply an elbow bend to one end of each of the bends e, the proper connectious
being made with the electric conductors. Of course it will be understood that the
conductors are conveyed to the house or other place of use in suitable insulated
conduits and are preferably distributed in the house also in insulated tubes.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what I
claim is :-
1. In an underground conduit system, a conduit comprising a tube or tubes
formed of a base of porous fibrous material and a filling of a bituminous com-
pound combined with said base throughout its mass, said tube or tubes being held
apart from one another and incased in a water proofing and insulating cement, as
black petroleum pitch, substantially as set forth.
2. In an underground conduit system, a conduit comprising a tube or tubes
formed of a base of porous fibrous material and a filling of a bituminous com-
pound combined with said base throughout its mass, said tube or tubes being held

page_text: apart from one another and incased in a waterproofing and insulating cement, as
black petroleum pitch, and the whole held in a trough of wood treated with a
water-proofing material, substantially as set forth.
3. The combination of tubes forming wire ways, a trough for said tubes having
grooves in its opposite sides and holes in its bottom, and upright and cross pieces
fitting respectively in said grooves and holes, whereby said tubes are held separate,
substantially as set forth.
4. A man hole or hand hole having double side walls with a water proofing
cement or liquid between said walls, substantially as set forth.
5. A man hole or hand hole having double side and bottom walls with a water-
proofing cement or liquid between said walls, substantially as set forth.
6. The combination in a man hole having a double walled body portion and a
filling of a water-proofing cement or liquid and a hollow cover adapted close said
body portion and be distended to effect a water proof joint, substantially as
set forth.
7. A cover for an underground man hole, comprising elastic plates, a rigid
annulus between said plates, and a cock on one of said plates for the purpose of
permitting a liquid under pressure to be forced between them, substantially as
set forth.
8. In a cover for an underground man hole, the combination with flexible plates,
rigid annulus, and cock, of elongated bolt holes in said annulus, substantially as
set forth.
9. The combination in an underground man-hole of a cover provided with
flexible plates adapted to be distended by having a fluid under pressure forced
between them, and a seat for the under plate of said cover provided with a
packing substantially as set forth.
10. The combination in an underground man-hole of a section of said man
hole provided with a seat and elongated bolt holes, of a cover provided with
flexible plates adapted to be distended by having a liquid forced between them,
and provided with bolts having elongated heads, whereby said cover may be
brought to make a tight connection with said section of man hole, substantially
as set forth.
11. A man hole for underground systems of electrical distribution formed with
a lower section into which the conduits enter, and the upper section adapted to be
put in place after the conduits have been laid in the lower section and provided
with suitable covers, substantially as set forth.
12. A man-hole for underground systems of electrical distribution formed with
a lower section into which the conduits enter, and the upper section provided
with depending flanges P, Q, said upper section being adapted to be put in place
after the conduits have been laid in the lower section, and provided with suitable
covers, substantially as set forth.
13. The combination in an underground system of electrical distribution, of a
double jacketed man hole, a conduit passing through openings in said man hole, and
a flange surrounding said man hole between the walls of said conduit, whereby
when a waterproofing cement or liquid is poured into the space between the walls
of said man-hole, a double seal is effected, substantially as set forth.
14. In a house junction box for an underground conduit system, a laterally
arranged projection or box, and a section of gradually curved wire way tube
entering said box, said tube being provided within said box with a removable
section, substantially as set forth.
15. In a man hole junction box, the combination with wire way ducts, of liquid
insulating material surrounding said ducts within the junction box, substantially as
set forth.
16. The combination in a junction box for branch connections, of nipples
receiving the ends of the wire way tubes, and cementing material between said
nipples and tubes, said box being adapted to receive after the connections have

page_text: been made, an insulating casing for the wires connected with the same, substantially
as set forth.
17. A connector for wire way tubes in an underground system, comprising a
split sleeve for surrounding the conductor between the tube ends, a two part tube
covering the joints of the split sleeve, and an outer tube covering the joint of the
two part tube, substantially as set forth.
Dated this 7th day of April 1891.
B. J. B. MILLS.
By Harris & Mills,
23, Southampton Buildings, London, Agents.