Improvement in and relating to Lampholders for Incandescent Electric Lamps.
Year: 1895

page_text: Date of Application, 11th Jan., 1895
Complete Specification Left, 7th Oct., 1895-Accepted, 4th Jan., 1896
PROVISIONAL SPECIFICATION.
Improvement in and relating to Lampholders for Incandescent
Electric Lamps.
GEORGE CHRISTOPHER CANNON c/o Central Restaurant Bellshill Lanarkshire
N.B. Electrical Engineer do hereby declare the nature of this invention to be as
follows :-
Consists of a metal tube, as is usually employed for the purpose, having the
ordinary angular slots in its sides at that end in which the cap of the lamp is
inserted, which tube and slots are of a size to admit of the lamp being held in position
when suspended therein.
The tube is enlarged in size about two-thirds of its length, the enlarged portion
being farthest from the lamp; this enlargement forms a shoulder upon which a disc
of hard non-conducting material is placed. This disc will be called A for con-
venience in future. It must be so fitted as to move freely in the longitudinal
direction of the tube but must not turn round therein. This may be accomplished by
raising a dent or blister on the surface of the metal inside the tube, at a particular
point, where a corresponding notch in the edge of the disc A, must be made
to suit.
The disc A has screwed into that side which faces the lamp, two small binding
screws corresponding in position with the centres of the contact plates on the lamp-
cap, against which they will be caused to press. Adjoining the binding screws are
two small holes in the disc A, which admit the conductors conveying the current
to the lamp.
At the opposite end of the tube from that into which the lamp is fitted, is a disc
of hard non-conducting material (called B in future references) fitting the end of
the enlarged portion of the tube and provided with a filler which prevents its
slipping inside, but is smaller than the external diameter of the tube, up to which
it must not extend.
A spiral spring is placed below the disc B, passing round the interior of the
tube and working freely therein, resting on the outside edge of the disc A, and
between it and the disc B. Two holes to admit the insulated conductors are
provided in the disc B, corresponding in position with those in the disc A.
A nipple of conical shape and hard non-conducting material, is provided to suit
the exposed face of the disc B, to which the base of the nipple is equal in diameter.
The nipple has a hole passing through it vertically from its apex to its base,
where the size of the hole is enlarged to slightly less in diameter than the distance
between the centres of the two holes in the disc B, it being in the first instance only
just large enough to admit the twin insulated conductors.
The metal tube, to which these fittings are mounted, is screwed along its
enlarged outside portion, admitting of a screwed metal ring being placed thereon.
This ring keeps the nipple in position by means of a lip which overlaps the base of
the nipple, the cone or apex projecting through the centre of the ring.
The twin insulated conductors pass through the hole in the nipple, and separate
one into each hole in the disc B, through the middle of the spring, through the
holes in the disc A, thence to the binding screws which secure them. The metal
ring, on being screwed home on to the tube, binds the nipple against the insulated
conductors passing through and between it and the disc B, in this way relieving the

page_text: binding screws in the disc A of any weight which might otherwise be thrown upon
them.
Having thus given a descriptive outline of the lamp holder, I will state briefly
what I claim to be my invention, namely:
The disc of insulating material carrying two binding screws (to which the
conductors are bound) the heads of which are caused to press against the contacts
of the lamp, by virtue of the spiral spring inside the holder having a tension against
the disc.
Dated this Tenth day of January 1895.
GEORGE CHRISTOPHER CANNON.
Improvement in and relating to Lampholders for Incandescent
Electric Lamps.
I, GEORGE CHRISTOPHER CANNON, 9 Hutcheson Street Glasgow, (lately
residing at Central Restaurant, Bellshill, Lanarkshire), Electrician, do hereby
déclare 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:-
Consists of a metal tube as is usually employed for the purpose, having the
ordinary angular slots in its sides, at that end in which the cap of the lamp is
inserted, or any other means may be employed to hold the lamp iu position, when
inserted in the lampbolder, against the terminals.
The tube is enlarged in size at about half its length, not two-thirds as I state in
my Provisional Specification, the enlarged portion being furthest from the lamp;
this enlargement forms a shoulder upon which rests a fitting of porcelain, A. It is
an easy fit in the tube and may be moved freely, but to prevent its turning round, a
point of metal is raised inside the tube, while a corresponding groove is provided in
the side of the porcelain fitting A, at G. This admits of A being moved freely in
the longitudinal direction of the tube.
The fitting A has a channel ou its upper side or face, in which a piece of
vulcanised fibre D, is placed; four holes pass thro' the porcelain between its lower
face and the bottom side of the channel. Two of these holes hold binding
screws C, C, which are screwed into the fibre D, their heads forming contacts with
the cap of the lamp; and through the holes adjoining them, pass the conductors
conveying the current.
At the enlarged end of the tube is another fitting of porcelain B, which is held
firmly in position by means of a suitable ring nut screwed on the tube and having
an overhanging lip which grips the edges of the porcelain. A spiral spring E, is
placed below the fitting B, passing round the interior of the tube and working
freely therein, and having a tension against the fitting A, and between it and B.
The twin insulated conductors enter the holder at the fitting B, by means of a
suitable nipple, thro' which is a hole in the centre large enough to receive them ;
they then pass through the spiral spring, where they may be protected from injury
by means of a ring of insulating material surrounding them; one conductor passes
to each side of the fibre D, which so lies between them, down the sides of the channel
in the fitting A, to the holes provided for them, through which they reach the
binding screws C, C, where their ends are made secure under washers placed beneath
the heads of the screws.
The screws C, C, being driven home into the fibre D, grip the conductors between
the corners of D and the porcelain at F, F, so that all strain is taken off the ends
of the conductors at the points of contact when the lampholder is suspended.
The metal tube is screwed along its external enlarged portion, so that suitable

page_text: ring nuts, screwed inside to fit it, may be placed thereon; one nut, before mentioned
in connection with the fitting B, being placed on the upper end of the tube,
and being provided at its upper face with a lip which overhangs inside so as to
overlap the upper surface of the porcelain fitting B, when in position, and to
prevent the fitting being displaced from the tube. The other ring being used
to support a suitable shade for the lamp.
Only the outline of the tube is shewn in the drawing, the ring nuts and
thickness of the tube being omitted as they are not necessarily part of my
invention; the upper portion of the fitting B, which is a nipple by which the
conductors enter the lampholder, is also omitted, being subject to alteration in the
various fixtures used to support it.
In the drawing shewn herewith,
Fig. 1 represents the internal arrangement of the lampholder, shewing the
lower portion of the fitting B, the projecting portion thereof inside the spiral
spring is used as a protection to the conductors, as is also the insulating ring
shewn adjoining below it, also surrounded by the spiral spring; a section of the
fitting A is also shewn, together with the binding screws C, C, and the piece of
vulcanised fibre D.
Fig. 2 represents a side view of the fitting A, the dotted lines marking the
courses of the binding screw entering the vulcanised fibre D; and the recess
in the porcelain, in which a washer rests under the screw head; together with the
position of a hole adjoining, and a groove in the side of the channel in which rests
the fibre D.
Fig. 3 represents a plan of the upper face of the fitting A, shewing the channel
across it, into which enter the four holes from the base; also shewing the grooves
at each side of the channel.
Fig. 4 represents the plan of the base of the fitting A, shewing the lower ends
of the four holes, the recesses for the washers, and the end of the groove at G,
which is coincidental, when in position, with a small piu or point of metal inside
the tube, which keeps the fitting A from turning round.
Having thus given a descriptive outline of the lampholder, I will state briefly
what I claim to be my invention, namely
The disc, or as I prefer to call it, fitting of porcelain or other insulator, carrying
two binding screws, to which conductors conveying the current are secured, the
heads of which binding screws are caused to press against the contacts of the
lamp, by virtue of a spring having a tension against the fitting or disc.
Dated this Fifth day of October 1895.
GEORGE CHRISTOPHER CANNON.