Improvements in and relating to Electric Light Switches and Wall Plugs.
Year: 1893

page_text: Date of Application, 17th Oct., 1893-Accepted, 18th Nov., 1898
UUMIDELE DT PTICATION.
Improvements in and relating to Electric Light Switches and
Wall Plugs.
I, GEORGE DAVIS of 46, Brookbank Road, Lewisham, Electrician, 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:-
My invention relates to improvements in electric light switches and wall plugs
in which the connecting or contact medium is quicksilver and in which the special
feature is as follows:-
It is at present largely the custom in electric lighting work to run the casing to
a certain point where the switch or wall plug is to be fixed, at this point a block
of wood is fixed, to receive the switch or wall plug. To obviate the use of this
block, ny switch and wall plug are expressly constructed to be fitted directly to
the casing itself. The objection to fitting ordinary switches and wall plugs which
have friction contacts direct to the casing is, that unless the said casing is very
securely fixed, the leverage or pull required to work these switches and wall plugs
would very often loosen the casing from its fixing.
By the use of quicksilver as a connecting medium, I do away entirely with the
necessity of leverage or pull, and thus avoid the risk of loosening the casing if
insecurely fixed.
In the accompanying drawings in which like letters of reference indicate corre-
sponding parts,
Figs. 1, 2, and 3 are a perspective, side view, and plan, of my improved block,
for single pole switches and wall plugs,
Figs. 4 and 5 are a front view and a side view respectively of a two pin contact
piece used in connection with the block shown in Figs. 1, 2, and 3, in the case of a
wall plug,
Fig. 6 is a plan and a side view of the pin used with the connecting piece shown
in Figs. 4 and 5,
Fig. 7 is a side view and an end view of a two pin contact or connecting piece
used with the block shown in Figs. 1, 2, and 3, in the case of a switch.
Figs. 1, 2, and 3 show the block which is made of porcelain, glass, or other
suitable insulating material, provided with two holes ef by means of which the
block can be screwed to the centre of the casing. The said block is furnished with
two slanting holes c d and two vertical holes ab which meet together viz. :
a meeting and b meeting d and are separated at the top by a dividing ridge r.
This block is the same for both switch and wall plug the only difference being in
the pin piece used for completing the circuit, which will now be described.
Figs. 4 and 5 show the two pin connecting piece used in connection with the
block, in the case of a wall plug.
It consists of two pieces of copper wire w w¹ bent into the required shape as
shown in Fig. 6, the end w² being inserted in the wooden insulator m and a small
brad y knocked into the wood on the other side, serves to keep them steady and in
place. The pins are fixed at the required distance apart so as to fit into the
centre of the holes a b of the block S, and a slight slant is given to them in order
to keep the wooden insulator m upright when in position, in the holes a b, the said
holes being larger than the pins. The connecting ends of the lamp wires are
brought through the holes g h and are secured to the pins w w¹ by the screws s.
For the insulating piece m some hard wood such as teak is used, and is cut to
such a shape that the projecting part covers the working parts under it, when in
the working position, as shown in Fig. 5.

page_text: $
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Fig. 7 shows the two pin contact or connecting piece used in connection with the
block S in the case of a switch.
It consists of a single piece of copper wire n passed through a hole drilled in the
wooden insulator m and then bent into the shape shown in the drawing, so as to fit
into the centre of the holes ab of the block S. A small hole z is drilled through
the insulator m through which a cord may be passed in order to suspend the contact
piece by the side of the block, when not in use.
:―
The method of working is as follows:-
The block having been screwed into position on the casing, the leading in wires
are brought from the casing grooves directly over the holes c d of the block S, and
are measured and cut off exactly long enough to reach to the bottom of the
aforementioned holes c d and after removing about half an inch of insulation, the
wires are inserted in the said holes c d. This having been effected, sufficient
quicksilver to reach up about half way is poured into the holes a b. To complete
the circuit, the contact or connection piece shown in Fig. 7 is inserted in the
holes ab in the case of a switch, and that shown in Figs. 4 and 5 is inserted in the
case of a wall plug.
Quicksilver being of low conductivity is simply used as a contact or connecting
medium, its duty as a conductor being reduced to almost nil, as the copper pins of
the pieces shown in Figs. 4, 5, and 7 are long enough to reach to the bottom of the
holes a 6 of the block S, so as to touch or be in close proximity to the ends of the
leading in wires lying at the bottom of the slanting holes c d of the block S.
Having now particularly described and ascertained the nature of my inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The new or improved wall plug provided with quicksilver as a contact medium
and consisting of the block S (Figs. 1, 2, and 3) furnished with slanting holes c d
(wherein enter the ends of the leading in wires) and vertical holes ab meeting
together at the bottom, in combination with the contact or connecting piece
described and shown with reference to Figs. 4 and 5 of the accompanying
drawings.
2. The new or improved switch provided with quicksilver as a contact medium
and consisting of the block S (Figs. 1, 2, and 3) furnished with slanting holes c d
(wherein enter the ends of the leading in wires) and vertical holes a b which meet
together at the bottom, in combination with the contact or connecting piece
described and shown with reference to Fig. 7 of the accompanying drawings.
3. The new or improved switch and wall plug, arranged, constructed, and
operated, substantially as herein described and shown in the accompanying
drawings.
Dated the 17th dar
1000
F. G. CASSELL,
Of Cassell & Co.,
22, Glasshouse Street, Regent Street, London, W.
Agent for the Applicant.