Improvements in the Covers or Domes of the Switches of Electrical Glow Lamps, which Improvements are also applicable to other Electrical Switches.
Year: 1897

page_text: PREVARUNAL SPECIFICATION.
Improvements in the Covers or Domes of the Switches of Electrical
Glow Lamps, which Improvements are also applicable to other
Electrical Switches.
I, RICHARD GEORGE EVERED, Director of Evered and Company. Limited, Barnet
Works, Birmingham, in the County of Warwick, Manufacturers, do hereby
declare the nature of this invention to be as follows:-
The domes or covers of the switches of electrical glow lamps to which my
invention is particularly applicable are made of sheet metal and of an ornamental-
figure the object of the said domes being to cover and protect the switch mech-
anism.
Domes or covers of the ordinary kind have the inconvenience when electrical
currents of high voltage are employed of short circuiting the electrical current
and thereby causing the extinction of the lamp and the object of my invention
is to prevent the liability to short circuiting in the domes or covers of electrical
switches.
In order to effect this I line or coat the interior of the dome or cover with a
coating of vulcanite or hardened india-rubber or gutta percha or any other in-
sulating material which is solid when cold but plastic when moderately heated.
I form the said lining by fashioning it in a mould while in a plastic state and
apply it while still warm and plastic to the interior of the dome or cover and
press it into close contact therewith. On cooling, the said lining is firmly
attached to the metallic dome or cover and constitutes an electrically insulating
lining to the interior of the said dome or cover which lining prevents the said
dome or cover effecting the short circuiting of the electrical current when the
lamp is in use.
Or instead of the compositions herein before referred to I effect the desired
object by the use of a solution of india-rubber or other insulating material. For
example, a solution of india-rubber in bisulphide of carbon may be employed the
said solution being spread by means of a brush on the interior of the dome or
cover. Or the said solution may be applied by being poured into the dome or
cover and by inclining the said dome of cover made to run upon and cover the
whole of the interior of the said dome or cover.
On the evaporation of the bisulphide of carbon a film of india-rubber firmly
attached to the interior of the dome or cover is left and constitutes an effective
nsulator which prevents the short circuiting referred to.
Or a solution of resinous matter such as shellac dissolved in alcohol or methy-
ated spirit may be employed and generally resinous varnishes or drying linseed
il may be employed.
Although my invention is especially applicable to the domes or covers of the
Price 8d

page_text: switches of electrical glow lamps yet my invention is also applicable to the covers
or cases of other electrical switches in which there is a liability to short circuiting.
Dated this Ninth day of November 1897
Improvements in the Covers or Domes of the Switches of Electrical
Glow Lamps, which Improvements are also applicable to other
Electrical Switches.
I, RICHARD GEORGE EVERED, Director of Evered and Company Limited, Barnet
Works, Birmingham, in the County of Warwick, Manufacturers, do hereby
declare the nature of my invention and in what manner the same is to be per-
formed to be particularly described and ascertained in and by the following state-
ment:-
The domes or covers of the switches of electrical glow lamps to which my
invention is particularly applicable are made of sheet metal, the object of the
said domes being to cover and protect the switch mechanism.
Domes or covers of the ordinary kind have the inconvenience when electrical
currents of high voltage are employed of short circuiting the electrical current
and thereby causing the extinction of the lamp and the object of my invention
is to prevent the liability to short circuiting in the domes or covers of electrical
switches.
In order to effect this I line or coat the interior of the dome or cover with a
coating of vulcanite or hardened india-rubber or gutta percha or any other in-
sulating material which is solid when cold but plastic when moderately heated.
I form the said lining by fashioning it in a mould while in a plastic state and
apply it while still warm and plastic to the interior of the dome or cover and
press it into close contact therewith. On cooling the said lining is firmly
attached to the metallic dome or cover and constitutes an electrically insulating
lining to the interior of the said dome or cover which lining prevents the said
dome or cover effecting the short circuiting of the electrical current when the
lamp is in use.
Figure 1 of the accompanying drawing represents half in elevation and half
in section and Figure 2 in plan of underside, a cover or dome of the ordinary kind,
that is, before the application thereto of the insulating lining constituting my
invention; Figures 3 and 4 are similar views of the said cover or dome after the
application thereto in the way herein before described of a vulcanite or insulating
lining.
In the said Figures 3 and 4 the outer metallic cover or dome is marked a and the
insulating lining is marked b.
Instead of the compositions herein before referred to, I may effect the desired
object by the use of a solution of india-rubber or other insulating material. For
example, a solution of india-rubber in bisulphide of carbon may be employed, the
said solution being spread by means of a brush on the interior of the dome or
Or the said solution may be applied by being poured into the dome or
cover and by inclining the said dome or cover made to run upon and cover the
whole of the interior surface of the said dome or cover.
cover.
On the evaportation of the bisulphide of carbon a film of india rubber firmly
attached to the interior surface of the dome or cover is left and constitutes an
effective insulator which prevents the short circuiting referred to.

page_text: Or a solution of resinous matter such as shellac dissolved in alcohol or methy-
lated spirit may be employed and generally, resinous varnishes or drying linseed
oil may be employed.
Although my invention is especially applicable to the domes or covers of the
switches of electrical glow lamps yet my invention is also applicable to the covers
or cases of other electrical switches in which there is a liability to short circuiting.
Having now particularly described and ascertained the nature of my invention
and in what manner the same is to be performed I declare that I claim as
my invention of "Improvements in the covers or domes of the switches of
electrical glow lamps which improvements are also applicable to other electrical
switches"-
First Lining the metallic covers or domes of electrical switches with vulcanite
or hardened india rubber or gutta percha or any other insulating material which is
solid when cold but plastic when moderately heated by moulding the said insulat-
ing material and applying it while warm to the interior of the cover or dome so
as to firmly attach it thereto substantially as herein before described and illustrated
in the accompanying drawing.
Secondly; Coating the interior of the metallic covers or domes of electrical
switches by applying a solution of india rubber, resin or the like thereto and allow-
ing the solvent of the said india rubber, resin or the like to evaporate and thereby
leave an insulating film on the interior of the cover or dome substantially as herein-
before described.
;
Thirdly Insulating the interiors of the covers or domes of electrical switches
by applying thereto a coating of drying linseed oil substantially as hereinbefore
described.
Dated this Twenty-seventh day of June 1898.
RICHARD GEORGE EVERED.