Year: 1887

page_text: Date of Application, 5th Oct., 1887
Specification Accepted, 11th Nov., 1887
I, ROBERT THORBURN TURNBULL, of 50 Old Broad Street, in the City of London,
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:-
This invention relates to improvements in fittings for incandescent electric-lamps
and has for its object the provision of means which, while allowing of the ready
removal of the lamp from the hooked spring terminals ensures that no short circuiting
between these terminals shall occur, while further the fitting is so arranged and
constructed as to allow of the ready removal or adjustment of its several parts.
To allow of the desired degree of flexibility of the hooked spring terminals (so
permitting of the ready removal and replacement of the lamp) without the risk of
short circuiting due therefrom, the terminals are constructed in accordance with the
method described in my Application for Letters Patent dated 4th of June 1887 and
numbered 8076.
To allow of the ready removal of the parts I, preferably, make the body of the
fitting in the shape of a hollow cylindrical brass casting having its lower part, or
base, greater in diameter than the upper part, or neck.
The base is chambered out for a sufficient distance to admit of a cylindrical block,
or plug, of insulating material being inserted therein, the hooked spring terminals
being secured in, or mounted upon the block, or plug, of insulating material as
described in the herein before mentioned Application for Letters Patent. This block,
or plug, of insulating material enters the chamber freely, and is firmly, and rigidly,
secured therein by an inwardly flanged ring, screwing upon the outer screw-threaded
surface of the base of the fitting, the flange projecting sufficiently inwards as to
overlap the edge of the block, or plug, and so effect its rigid locking in place. This
flanged ring also carries the bow, or other, springs for steadying the lamp, and
keeping in tension, when the lamp is in position, the hooked spring terminals with
which the fitting is provided. Further, by making the flanged ring of a sufficient
diameter its upper surface is made to serve as a support for a shade, or globe, a second
ring, also threaded to fit the screw-thread on the base, serving to secure the shade, or
globe, in place, a flexible washer, or washers, being interposed between the metal and

page_text: glass, if desired. Or the second ring may be provided with arms so as to form a
shade, or globe, carrying gallery.
The hollow neck of the fitting is externally screw threaded, and provided with an
outer thimble, or cover, internally threaded to screw thereon. The top of the opening
through the neck is coned outwards while an inwardly coned opening passes through
the thimble or cover, a piece of wood, or other insulating material being shaped to fit
the double conical space or recess so formed. This piece of wood is split, in the
direction of its length, into two or more parts, a central aperture being left through
which the leads or wires pass. If now the coned thimble be placed over the parts and
screwed down on them it follows that they will be closed together and caused to clamp
the leads, or wires, passing through the central aperture.
Having thus set forth the nature of my invention and shown in what manner the
same is to be carried into effect I will now proceed to more particularly describe the
same, reference being made to the accompanying drawings.
Figure 1 shows a sectional elevation of a fitting constructed in accordance with this
invention, Fig. 2 being a plan of the same and Fig. 3 an elevation on a plane at right
angles to Fig. 1. In these figures a, a are the hooked spring terminals constructed
as described in my Application for Letters Patent No. 8076 of June 4th: 1887, and
mounted in a block or plug of insulating material A. The block A is turned to fit the
chamber in the base B of the fitting, and is rigidly held in place by the flange b, of
the ring C. The block A is provided with openings t, t, through which the leads or
wires pass on their way to the terminals a, a. The ring carries the bow, or other,
springs c and is made sufficiently large in diameter to carry on its upper surface d a
globe, or shade, which is locked in place by the ring D, a flexible washer, or washers,
being inserted between the metal and glass if desired. Or the ring D may be
provided with arms so as to act as a gallery. The neck E of the fitting is provided
with an outer thimble, or cover, T and split wooden plug F, coned as shown, and
through the aperture of which the leads or wires pass.
I am aware that the device shown at the neck of the fitting for clamping the leads
or wires and consisting of the thimble or cover, coned recess, and wooden plug, is not
new and I therefore make no claim to this part of the arrangement.
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 :-
First. Mounting the hooked spring terminals of an incandescent lamp fitting in
such a manner as will allow of their being bodily removed from the fitting, in the
manner substantially as hereinbefore described and illustrated.
Second. The securing together of the parts of an incandescent lamp fitting by a
flanged ring, which serves also as a shade, or globe carrier, and to carry the bow or
other springs for steadying the lamp and putting the terminal springs in tension,
substantially as hereinbefore described and illustrated.
Dated this 5th day of October 1887.
F. SEATON SNOWDON,
Agent for the Applicant.