Improvements in or Connected with Incandescent Electric Lamps.
Year: 1887

page_text: Date of Application, 6th Dec., 1887
Complete Specification Left, 5th Oct., 1888
Complete Specification Accepted, 9th Nov., 1888
PROVISIONAL SPECIFICATION.
Improvements in or Connected with Incandescent Electric
Lamps.
I DAVID URQUHART, of 4 The Sanctuary, in the City of Westminster, Electrical
Engineer, do hereby declare the nature of this Invention to be as follows:-
:-
The object of my Invention is to provide means in connection with incandescent
electric lamps whereby should fracture occur of the glass which encloses the lamp or
the filament be broken the electric current will be discontinued and the lamp
extinguished. This is especially desirable in such applications of the electric lamps
as to mining purposes or in powder magazines or the like where there is danger of
igniting explosive gases or materials.
According to my Invention I support a contact which completes the circuit to the
lamp by means of the lamp glass or enclosing glass a spring or springs constantly
tending to break the contact but being prevented from so doing by the glass.
The glass should he of the description called toughened so that it will not merely
crack.
On the glass being fractured it no longer prevents the spring or springs from
breaking the contact and consequently it or they immediately act to extinguish the
lamp.
1
1007
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, W.C.,
Agents for the said David Urquhart.

page_text: Improvements in or Connected with Incandescent Electric
Lamps.
I DAVID URQUHART of 4 The Sanctuary in the City of Westminster 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:
The object of my Invention is to provide means in connection with incandescent
electric lamps whereby should breakage of the protecting glass of the lamp occur the
electric current will be discontinued and the lamp extinguished. This is especially
desirable in such applications of incandescent electric lamps as to mining purposes or
in powder magazines or the like where there is danger of igniting explosive gases or
materials.
According to my Invention I support a contact maker which completes the circuit
to the lamp by means of the protecting glass a spring or springs or equivalent
device constantly tending to break the contact but being prevented from so doing by
the glass.
The glass should be of the description called toughened so that it will not merely
crack.
On the glass being broken it no longer prevents the spring or springs or equivalent.
device from breaking the contact and consequently it or they immediately act to break
the circuit and so extinguish the lamp.
And in order that my said Invention may be fully understood I shall now proceed
more particularly to describe the same and for that purpose shall refer to the several
figures on the annexed sheet of drawings the same letters of reference indicating
corresponding parts in all the figures.
Figures 1 and 2 show an arrangement for the purpose Figure 1 showing the parts
when they are in their normal position and Figure 2 showing the parts in the position
they assume when the glass is broken. Figure 3 is a front view.
A is the protecting glass, covering the lamp B-C is a lever centered at c and acted
upon by a spring & whose force tends to depress the lever but is normally prevented
from doing so by the outer end of the lever bearing against the glass A. The inner
end of the lever normally makes contact between the spring d and the centre e which
are in the circuit to and from the lamp so as to complete that circuit through the said
léver. When the glass is broken the lever being no longer supported by the glass
is pressed by tlie spring d into the position shown in Figure 2 so that the circuit
to the lamp is broken by the movement of the lever C and the lamp is
extinguished.
Figure 4 shows in vertical section another arrangement wherein the protecting
glass A enclosing the lamp B acts as a strut between the top of the cage g and the
disc h to which the lamp is fixed and forces down the disc h so that contact at e² f
is made and the lamp circuit is completed. The spring & exerts its force to press up

page_text: the disc h and lamp B but is prevented from doing so by the glass A. When the
glass breaks it no longer prevents the spring d² exerting its force to raise the disc
and lamp B and so break the contact between 2 and f and thus when the glass A
breaks the lamp circuit is interrupted and the light is extinguished.
Having now particularly described and ascertained the nature of my said Inven-
tion and in what manner the same is to be performed I declare that what 1
claim is :-
First. In combination with incandescent electric lamps a device which is supported
by the protecting glass in such a position that it completes the lamp circuit but will,
when the glass is broken interrupt the circuit and extinguish the lamp substantially as
herein before described.
Second. In combination with incandescent electric lamps the arrangement of safety
device consisting of a lever which is normally supported by the protecting glass in a
position to complete the circuit to the lamp but which is released when the glass
breaks so as to interrupt the circuit substantially as herein before described and
illustrated in Figures 1, 2 and 3 of the accompanying drawings.
Third. In combination with incandescent electric lamps a protecting glass which
normally maintains electric contact to complete the lamp circuit and a spring tending
to break the circuit but prevented from so doing by the said glass, so that when the
glass breaks the spring acts to interrupt the circuit to the lamp substantially
as hereinbefore described and illustrated in Figure 4 of the accompanying
drawings.

page_text: Date of Application, 6th Dec., 1887
Complete Specification Left, 5th Oct., 1888
Complete Specification Accepted, 9th Nov., 1888
PROVISIONAL SPECIFICATION.
Improvements in or Connected with Incandescent Electric
Lamps.
I DAVID URQUHART, of 4 The Sanctuary, in the City of Westminster, Electrical
Engineer, do hereby declare the nature of this Invention to be as follows:-
The object of my Invention is to provide means in connection with incandescent
electric lamps whereby should fracture occur of the glass which encloses the lamp or
the filament be broken the electric current will be discontinued and the lamp
extinguished. This is especially desirable in such applications of the electric lamps
as to mining purposes or in powder magazines or the like where there is danger of
igniting explosive gases or materials.
According to my Invention I support a contact which completes the circuit to the
lamp by means of the lamp glass or enclosing glass a spring or springs constantly
tending to break the contact but being prevented from so doing by the glass.
The glass should be of the description called toughened so that it will not merely
crack.
On the glass being fractured it no longer prevents the spring or springs from
breaking the contact and consequently it or they immediately act to extinguish the
lamp.
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, W.C.,
Agents for the said David Urquhart.

page_text: COMPLETE SPECIFICATION.
Improvements in or Connected with Incandescent Electric
Lamps.
I DAVID URQUHART of 4 The Sanctuary in the City of Westminster 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
The object of my Invention is to provide means in connection with incandescent
electric lamps whereby should breakage of the protecting glass of the lamp occur the
electric current will be discontinued and the lamp extinguished. This is especially
desirable in such applications of incandescent electric lamps as to mining purposes or
in powder magazines or the like where there is danger of igniting explosive gases or
materials.
According to my Invention I support a contact maker which completes the circuit
to the lamp by means of the protecting glass a spring or springs or equivalent
device constantly tending to break the contact but being prevented from so doing by
the glass.
The glass should be of the description called toughened so that it will not merely
crack.
On the glass being broken it no longer prevents the spring or springs or equivalent
device from breaking the contact and consequently it or they immediately act to break
the circuit and so extinguish the lamp.
And in order that my said Invention may be fully understood I shall now proceed
more particularly to describe the same and for that purpose shall refer to the several
figures on the annexed sheet of drawings the same letters of reference indicating
corresponding parts in all the figures.
Figures 1 and 2 show an arrangement for the purpose Figure 1. showing the parts
when they are in their normal position and Figure 2 showing the parts in the position
they assume when the glass is broken. Figure 3 is a front view.
A is the protecting glass, covering the lamp B-C is a lever centered at c and acted
upon by a spring d whose force tends to depress the lever but is normally prevented
from doing so by the outer end of the lever bearing against the glass A. The inner
end of the lever normally makes contact between the spring d and the centre c which
are in the circuit to and from the lamp so as to complete that circuit through the said
lever. When the glass is broken the lever C being no longer supported by the glass
is pressed by the spring d into the position shown in Figure 2 so that the circuit
to the lamp is broken by the movement of the lever C and the lamp is
extinguished.
Figure 4 shows in vertical section another arrangement wherein the protecting
glass A enclosing the lamp B acts as a strut between the top of the cage g and the
disch to which the lamp is fixed and forces down the disc so that contact at e2f2
is made and the lamp circuit is completed. The spring d² exerts its force to press up

page_text: the disc hand lamp B but is prevented from doing so by the glass A. When the
glass breaks it no longer prevents the spring d² exerting its force to raise the disc h
and lamp B and so break the contact between e³ and fand thus when the glass A
breaks the lamp circuit is interrupted and the light is extinguished.
Having now particularly described and ascertained the nature of my said Inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
:-
First. In combination with incandescent electric lamps a device which is supported
by the protecting glass in such a position that it completes the lamp circuit but will,
when the glass is broken interrupt the circuit and extinguish the lamp substantially as
herein before described.
Second. In combination with incandescent electric lamps the arrangement of safety
device consisting of a lever which is normally supported by the protecting glass in a
position to complete the circuit to the lamp but which is released when the glass
breaks so as to interrupt the circuit substantially as hereinbefore' described and
illustrated in Figures 1, 2 and 3 of the accompanying drawings.
Third. In combination with incandescent electric lamps a protecting glass which
normally maintains electric contact to complete the lamp circuit and a spring tending
to break the circuit but prevented from so doing by the said glass, so that when the
glass breaks the spring acts to interrupt the circuit to the lamp substantially
as hereinbefore described and illustrated in Figure 4 of the accompanying
drawings.