Year: 1886

page_text: Arrangement thereof.
I, BENJAMIN. JOSEPH BARNARD MILLS of the firm of Harris and Mills of
23 Southampton Buildings in the County of Middlesex, Patent Agent do hereby
declare the nature of said invention, a communication to me from abroad by
Luther Stieringer of the City, County and State of New York in the United
States of America, Electrician, to be as follows :-
Heretofore when incandescing electric lamps have been used in series, with
currents of high electro-motive force with an electro magnetic cut-out device for
closing a shunt around each. lamp when its carbon filament breaks, difficulty has
arisen in the following way.
If a break occurs in the filament, the current is apt to pass from the broken side
of the filament below the point of fracture across the vacuous space to the other
side forming an arc which follows down the carbon consuming the same and down
the leading in wires to the glass which being intensely heated becomes a conductor
of electricity so that the current continues to pass through the glass from one wire
to the other and so proceeds down to the lamp sockets and cut-out mechanism so
that these parts may be destroyed and the continuity of the series circuit is finally
broken. The passage across the carbon being provided for the current as soon as
the carbon breaks, the cut out mechanism of course does not act.
This invention relates to means for over coming this difficulty by breaking the
arc before it leaves the lamp, so that the electro-magnetic cut-out will then act to
shunt the lamp.
.
This is accomplished by filling the stem or tube through which the leading in
wires pass outside of the exhausted globe with a refractory insulating material
which is not injuriously affected by the heat of the arc or current and prevents the
arc from passing from the wire to the glass or from one wire to the other.
The substance which it has been found best to employ for the purpose is
asbestos fibre with which the stem or tube is filled. Numerous other substances have
however been tried with good results. Among these may be mentioned magnesium
[Frica 81:

page_text: calcite, powdered soap-stone and terra-alba. These substances are effective in
operation but the asbestos fibre is easier to handle and does not shift its position
like the other materials which are in the form of powder. Any refractory insu-
lating material not unduly affected by the arc may however be employed.
When lamps such as just described are used in series each one is provided with
a suitable electro magnetic cut-out device. If when the carbon breaks the arc is
not formed, which often occurs, the cut-out device acts at once to shunt the lamp
and maintain circuit to the rest of the series. And when the arc does occur
and is broken in the stem of the lamp the cut-out mechanism acts also in the
same way..
B. J. B. MILLS.
By Harris & Mills,
23, Southampton Buildings,
Agents.
COMPLETE SPECIFICATION.
:
Improvements in Incandescing Electric Lamps and in the
Arrangement thereof.
I BENJAMIN JOSEPH BARNARD MILLS of the firm of Harris and Mills of
23 Southampton Buildings in the County of Middlesex, Patent Agent, do hereby
declare the nature of this invention a communication to me from abroad by
Luther Stieringer of the City County and State of New York in the United
States of America, Electrician, and in what manner the same is to be performed,
to be particularly described and ascertained in and by the following statement :-
Heretofore when incandescing electric lamps have been used in series, with
currents of high electro-motive force with an electro-magnetic cut-out device for
closing a shunt around each lamp when its carbon filament breaks, difficulty has
arisen in the following way.
If a break occurs in the filament the current is apt to pass from the broken side
of the filament below the point of fracture, across the vacuous space to the other
side forming an arc which follows down the carbon consuming the same, and down
the leading in wires to the glass which being intensely heated becomes a conductor
of electricity so that the current continues to pass through the glass from one wire
to the other and so proceeds down to the lamp socket and cut-out mechanism so
that these parts may be destroyed and the continuity of the series circuit is finally
broken. The passage across the carbon being provided for the current as soon as
the carbon breaks, the cut-out mechanism of course does not act.

page_text: This invention relates to means for overcoming this difficulty by breaking the
are before it leaves, the lamp, so that the electro-magnetic cut-out will then act to
shunt the lamp.
This is accomplished by filling the stem or tube through which the leading-in
wires pass outside of the exhausted globe with a refractory insulating material
which is not injuriously affected by the heat of the arc or current and prevents the
arc from passing from the wire to the glass or from one wire to the other.
The substance which it has been found best to employ for the purpose is asbestos
fibre with which the stem or tube is filled. Numerous other substances have
however been tried with good results. Among these may be mentioned magnesium
calcite powdered soap-stone and terra-alba. These substances are effective in
operation but the asbestos fibre is easier to handle and does not shift its position
like the other substances which are in the form of powder any refractory insu-
lating material not unduly affected by the arc may however be employed.
When lamps such as just described are used in series, each one is provided with
a suitable electro magnetic cut-out device.
If, when the carbon breaks, the arc is not formed, which often occurs, the cut-out
device acts at once to shunt the lamp and maintain circuit to the rest of the series.
And when the arc does occur and is broken in the stem of the lamp the cut out
mechanism acts also in the same way.
And in order that the said invention may be more clearly understood and readily
carried into effect, I will proceed aided by the accompanying drawings more fully
to describe the same,
DESCRIPTION OF THE DRAWINGS.
Figure 1 is a diagram of a portion of a system of electric lighting embodying the
invention Figure 2 a view in elevation of one of the lamps; and Figure 3
section of the stem of the lamp after the arc has been formed and broken.
a
Like letters refer to corresponding parts in all these figures. A is the exhausted.
inclosing globe of an Edison electric lamp: B, is the inner tube or stem through
which the leading-in wires a a¹ pass being sealed in the glass of said tube when
they pass through it at b.
Č is the carbon filament attached to said wires at cc preferably by electro-plated
joints.
When the arc forms across the filament it usually passes from the broken side
thereof immediately below the fracture to the opposite clamp, both sides of the
filament are consumed at once and the wires usually are then consumed down to
the glass or nearly there.
The current then passes across through the glass and usually consumes only one
wire a as seen in Figure 3. Continuing on through the wires and glass the
current continues to prevent the operation of the cut-out and finally reaches and
destroys the socket and cut-out mechanism..
The stem B is however filled with asbestos fibre D or other suitable material as
before explained.
The stopper E inserted in the lower end of the stem holds the asbestos in it and
also keeps the wires apart.
At first, as seen in Figure 3, the wire continues to be consumed for a certain
distance down into the asbestos-that is until the distance becomes so great that
the current or are cannot pass from the end of the wire to the glass at b. As soon
as this point is reached it is evident that the arc must cease at once since the
asbestos prevents it from reaching the other wire direct, or from reaching the side
of the tube.
In Figure 1 is shown a cut-out device which may be employed. The lamps A, A-
are in series in lino L, L, in any suitable number.
In a shunt d d around each lamp is an electro-magnet F, whose spring-retracted
armature lever G controls at e another shunt f, f.

page_text: If circuit through the lamp is interrupted in either of the two ways above
described the magnet F attracts its armature and closes shunt ff around the lamp.
A catch g is provided which holds the shunt closed until the broken lamp is
replaced by a new one when the catch is withdrawn by hand and the shunt is
opened again.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, I declare that what
I claim is:-
1. In an incandescing electric lamp, the glass stem through which the leading-in
wires pass, filled with asbestos fibre or other suitable refractory insulating material
substantially as hereinbefore described.
2. Two or more incandescing electric lamps connected in series, each having the
glass stem through which the leading-in wires pass filled with asbestos fibre or other
suitable refractory insulating material in combination with electro-magnetic cut-
out mechanism for each lamp, substantially as hereinbefore described.
Dated this 24th day of September 1886.
"
B. J. B. MILLS.
By Harris & Mills, Agents,
23, Southampton Buildings.