Improvements in and connected with Electrical Conductors and Fittings Combined therewith.
Year: 1890

page_text: Date of Application, 31st Oct, 1890
Complete Specification Left, 18th July. 1891-Accepted, 22nd Aug., 1891
PROVISIONAL SPECIFICATION.
Improvements in and connected with Electrical Conductors and
Fittings Combined therewith.
DAVID COOK, 101 St. Vincent Street Glasgow, N.B., Electrical Engineer,
CARRINGTON RIDDELL GORDON SMYTHE, 140 Bath Street Glasgow N.B.
Electrical Engineer, ERNEST PAYNE 140 Bath Street Glasgow, N.B. Electrical
Engineer, do hereby declare the nature of this invention to be as follows:-
:-
Our invention consists of an arrangement of metal tubes placed one inside the
other to form an electric circuit. In our system we generally employ three tubes,
the two inner tubes for carrying the current, and forming forward and return
leads, and the third or outer tube as a mechanical protection. Sometimes for
series working we use only two tubes. We do not insulate the tubes with the
usual insulating materials such as india-rubber, gutta-percha, and the like, but
we use air insulation and separators composed of porcelain, glass, ebonite or other
suitable non-conducting and non-absorbent material, and made preferably in the
form of rings or of studs. When we employ rings we make them in one or more
pieces as required, and slip them over the inner tube or tubes so as to separate
one tube from the other, and the rings are held in position by means of plugs,
wedges, bands, clutches, or other suitable fastening. These rings are preferably
serrated or notched so as to have projecting parts usually three in number in order
that the surface in contact with the tube may be as small as possible to avoid
leakage of electricity, and also to allow the air to circulate more freely, and permit
drainage of any moisture that may accumulate. When studs are used as separators
we insert them at intervals in holes or suitable apertures in the tubes, and some-
times we pass the studs through holes in the middle tube so that they project both
inside and outside, and thus form a support for the inner tube and prevent the
outer tube from touching the second tube.
When the tubes are laid underground we prefer to make the joints air-tight and
to force in air at a pressure slightly above that of the atmosphere in order to
prevent the entrance of moisture or liquid in the event of a crack or leak occuring
in the tube. When moisture accumulates we sometimes pass heated air through
the tubes to dry them.
In jointing our conductors we fuse or weld the tubes together as there is no
insulating material that would be damaged by heating, or we braze or solder or
screw the tubes together, or let one into the other and if necessary fasten them
with small plugs or indents set down in the metal.
We also use sleeves for making the joints which can be made in sections to fit
over or round the tubes. We sometimes fasten the sleeve to one tube and
allow the end of the adjoining tube to slide freely inside or outside the sleeve
making the free end springy to ensure better contact. This arrangement permits
of contraction or expansion, and any rubbing due to this tends to keep a clean
metallic contact. When making angle joints we use cressed and Hat straps of
metal of the form of angles, or Ts, or bends, and we also employ strips soldered to
either tube, or spirals composed of metal strip or tape or wire which can be bent
round any curve or angle required, any contraction or expansion of the tubes being
readily taken up by these flexible connections. For jointing the tubes we sometimes
employ a jointing-box into which the ends of the tubes are fitted, and we usually
employ them when taking off a branch from a main. And when contraction and
expansion of the tubes are to be allowed for we employ a jointing box of this kind;
the tube or tubes are fixed into the hox at one end and are left free at the other
end where they pass into the next box and are there clipped or held by springy

page_text: •
contacts which allow them to expand and contract freely. For supporting and
fixing these tubes we use, hooks or rings at intervals fastened to the walls, or
ceiling, or girders, or other support, to which the tubes can be fixed or through
which they can slide if desired. When the tubes are laid in conduits we sometimes
fasten these rings into stone, concrete, or other suitable blocks.
We usually
support the tubes at the places where the above mentioned jointing boxes are
inserted by making these boxes of such form that they can be secured to the
ceiling, or wall, or other support by means of screws bolts and the like, or fastened
to suitable brackets or uprights, or into blocks of stone or concrete, when used
underground according to the place or position in which the tubes may have to be
fixed. The jointing boxes thus form supports for the tubes. For convenience we
sometimes use this jointing box to contain the switch, or fuse, or both, especially.
when it is required to lead off a branch from the box. This jointing-box can this
be used as a combination ceiling-rose, switch-box, fuse box and support for the
tubes, and for any other fitting such as pulleys and cords for raising or lowering a
lamp. The switches which we employ in our system are of such form 'as to break
and make the continuity of either or both of the tubes forming the forward or
return lead. The moving part is generally of the form of a sleeve or part of a
sleeve or a plug fitting internally or externally, and made springy or fitted with a
spring so as to secure good contact, and sometimes actuated by a spring to give
a quick break. We also employ any suitable switch mounted preferably on an
nsulated base and attached to the inside or the outside of the jointing box.
When out of reach we attach cords or rods to the switch lever or handle to work
the same.
Fuses may also be fixed in a similar manner to the inside or outside
of the jointing-box. We also use a jointing-block for supporting the ends of the
tubes and for facilitating the making of joints. We make these blocks of insulating
material such as porcelain vulcanised-fibre or the like. And we form these blocks
with steps on one or more sides projecting in such a manner as to fit into the
ends of the tubes, so as to support them. Holes or grooves are made in the block
to allow for the passage of wires, strips, or other jointing pieces with which we
connect one tube with another.
Dated this 29th day of October 1890.
DAVID COOK.
CARRINGTON R. G. SMYTHE.
ERNEST PAYNE.
'COMPLETE SPECIFICATION.
Improvements in and connected with Electrical Conductors and
Fittings Combined therewith.
We, DAVID COOK, of 101 St. Vincent Street, Glasgow, North Britain, Electrical
Engineer, CARRINGTON RIDDELL GORDON SMYTHE, of 140 Bath Street, Glasgow,
North Britain, Electrical Engineer, and ERNEST PAYNE, of 140 Bath Street,
Glasgow, North Britain, Electrical Engineer, do hereby declare the nature of this
invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:
Our invention relates to the construction of electric conductors 'consisting of
concentric metal tubes insulated from each other by the air spaces between them,
and kept apart by rings or studs of non-conducting material placed at suitable
intervals.
We shall describe several constructions of such tubular conductors, and of their
branches and fittings, referring to the accompanying drawings.
As shewn in longitudinal section Fig. 1. there are two tubular conductors, the
inner tube A and the middle tube B with an 'outer tube Cas a protector. The
tubes B and C are screwed into T pieces D and E, into which are screwed
the branches B and C'; the middle conductor of the branch is shewn as a wire A'

page_text: screwed into the tube A, but obviously it might be a tube screwed into a T piece
of the tube A. Studs S of insulating material are fixed at intervals in holes of the
tubes keeping them apart in their concentric positions.
It may be readily understood that when instead of having a branch, the main
conductor has to make a right angled bend the connection of the one part to the
other is made by elbow pieces instead of T pieces.
As shown in longitudinal section Fig. 2. and transverse section Fig. 24 a socket F
fixed on the outer tube C receives the branch C' which may have its end slit so as
to spring into the socket; the branch tube B¹ is inserted in a lateral hole of B, and
its end may be slit so as to be sprung in; or may be threaded so as to be screwed
in the branch wire A' terminates in a spring clip which is sprung on the tube A..
All the parts of the branch when held by spring pressure may be detached when
desired.
Fig. 3 shews a branch like that in Figs. 2 and 24 adapted to form the socket for
a glow lamp. The tubes A. B and C in this case are shewn to be kept apart by
rings B of insulating material, which, as shewn to an enlarged scale by Fig. 34
should have parts of their external and internal circumferences cut away leaving
only narrow projections to bear on the tubes, thus allowing free passage along
the air spaces between the tubes.
Fig. 4. is a side view and Fig. 5 is a plan of a junction box which is a convenient
form of connection to the conductors in cases where they have to be provided with
supports or with appliances such as switches and safety fuses. As shewn in Fig. 4
the junction box J is carried from a ceiling by a rod G, and from it descend con-
ductors H for a lamp. Obviously the junction box might be inverted so as to be
supported on a pedestal and to carry a lamp or set of lamps with their conductors
proceeding upwards from it. On the one side of the box may be a switch K
worked by a lever & and on the other side there may be a safety fuse L.
Fig. 6. is a longitudinal section shewing a sliding switch for the concentric tubes.
It consists of a pair of tubes a and b which fit so as to slide over the tubes A and B
respectively. They are kept apart by inner insulating rings, they are guided by
a ring, and are moved to and fro by an outer ring which is fixed to the ring
and tube b by pins passing through slots of the outer casing C².
In all cases a solid rod or wire may obviously be substituted for the central
tube A, the whole conductor then consisting of this central rod or wire for the one
lead, the tube next surrounding it for the other lead, and the outermost tube for
giving strength and protection.
By thus constructing tubular conductors, whether the central lead be a tube.or
wire, we obtain great strength and stiffness consistently with lightness, we dispense
with all fusible or combustible insulating material, using only studs or rings which
may be of glass or ceramic material, for separating the tubes, so that they are
practically insulated by the air between them. As there is free passage along
the air spaces they can easily be drained in case water should get in, and warm
dry air can be forced through them to render their insulation complete. The
outer tube and its junctions and attachments can be made of an ornamental
character and can be utilised as a picture rod or curtain pole, and as there is no
electrical connection with this tube, there is no danger of shocks or fire being
caused by contact with it.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
1. An electrical conductor consisting of concentric tubes kept apart by studs or
rings of non-conducting material placed at intervals, so that the tubes are insulated
from each other chiefly by the air spaces between them, substantially as described.
2. In combination with a conductor such as is above referred to, branch con-
ductors of similar construction, connected to the main conductors by T pieces,
substantially as described.

page_text: 3. In combination with a conductor such as is above referred to, a junction box,
with support, switch, safety fuse or like appliances, substantially as described.
4. A. sliding switch for concentric tubular conductor, substantially as described
with reference to Fig. 6.
ABEL & IMRAY,
Agents for the Applicants.