IMPROVEMENTS IN ELECTRIC LAMPS, IN THE MANUFACTURE OF PARTS THEREOF, AND MEANS OF TURNING ON AND OFF ELECTRIC CURRENTS, FOR LIGHTING AND EXTINGUISHING LAMPS OR FOR OTHER PURPOSES."
Year: 1881

page_text: LETTERS PATENT to St. George Lane Fox, of Rushmore, in the County of
"
Wilts, for an Invention of IMPROVEMENTS IN ELECTRIC LAMPS, IN THE
MANUFACTURE OF PARTS THEREOF, AND MEANS OF TURNING ON AND OFF
ELECTRIC CURRENTS, FOR LIGHTING AND EXTINGUISHING LAMPS OR FOR
OTHER PURPOSES."
PROVISIONAL SPECIFICATION left by the said St. George Lane Fox at
the Office of the Commissioners of Patents on the 18th January 1881.
ST. GEORGE LANE Fox, of Rushmore, in the County of Wilts. "IMPROVEMENTS
IN ELECTRIC LAMPS, IN THE MANUFACTURE OF PARTS THEREOF, AND MEANS of
TURNING ON AND OFF ELECTRIC CURRENTS FOR LIGHTING AND EXTINGUISHING
LAMPS, OR FOR OTHER PURPOSES."
My Invention consists of improvements in electric lamps, of the manufacture of
improved burners or "luminous bridges" for such lamps, and of means of turning on
and off electric currents for lighting and extinguishing the lamps, the said means
being also applicable to turning on and off electric currents for other purposes.
The improved lamps and luminous bridges or burners, and the means of turning
on, and off electric currents, may be used in conjunction with the system of
distribution and regulation of electric currents, as explained in the Specifications
of several former Letters Patent granted to me, and dated respectively 9th October
1878, No. 3988; 12th October 1878, No. 4043, and 14th November 1878, No. 4626,
or otherwise.
In my improved lamps I insert the ends of the luminous bridge or burner,
whether made in the manner hereinafter described or otherwise, into spirals formed
of platinum wire, in which they fit tightly; and in order to cement the two together,
I coat the spirals and the said ends with Indian ink, which I find makes a good
connection, particularly after it becomes charred by the heat of the lamp. I fuse
the upper part of the platinum wires into pieces of English lead glass in the neck
of the lamp, flask, or globe; the upper ends of these wires extend through the said
glass into tubes containing mercury, into which the conducting wires dip. The top

page_text: of the tubes and the neck of the flask or globe may be closed as described in a
Provisional Specification lodged by me on the 28th August 1880, No. 3494, or in
any other suitable manner. I form the body of the flask or globe of German glass,
that is to say, of glass without lead in its composition, as I find it more easy of
manufacture, but the part in which the platinum wires are fused as above described
should be of lead glass, as without the lead the platinum and glass will not adhere
together without difficulty, and the glass is liable to crack.
I exhaust the lamp by preference as described in my Provisional Specification
above referred to, and I find it desirable to continue the exhausting process for
about two days.
In order to manufacture the burners or luminous bridges for electric lamps, I
wind thread, string, or tape of flax, or other vegetable fibre, around a block or piece
of graphite or gas carbon of suitable shape or dimensions, into which block I have
previously let a piece of steel or other metal capable of withstanding the heat,
hereinafter described. The piece of steel projects from the periphery of the block
in the form of a knife edge. To prevent the convolutions or turns of the thread,
string, or tape getting displaced, I bind them with string; I place the block (a
number at a time) with its convolutions of thread into a hermetically closed crucible,
which I raise to a bright white heat. The thread thus becomes baked; in so doing
it shrinks, and each turn or convolution breaks, but as the piece of steel acts as a
.cutting edge all the convolutions break in the same line. The size of the blocks,
and therefore of the convolutions, and the thickness of the threads are regulated
according to the lighting power required. The baked threads are removed from
the blocks and placed in suitable numbers in clips or holders, and immersed in an
atmosphere of coal gas or other carbon compound, while an electric current is passed
through them, so as to raise them to a white heat. The baked threads are at first
of so high a resistance that it is difficult to get to pass through them an electric
current of sufficient strength to produce incandescence. I find I can overcome
this difficulty by connecting the threads directly with a dynamo-electric machine,
or other electric generator, by then momentarily short circuiting the machine, and
suddenly breaking contact through the short circuit; the result of this is that the
extra current set up has so high an electro-motive force as to momentarily raise
the baked threads to a state of incandescence, during which time the resistance is
diminished, owing to the deposit of carbon on the surface. I repeat the operation
a number of times until a current of moderate electro-motive force will raise the
threads to a white heat, and I keep up this current of moderate electro motive
force, until the resistance of the threads is reduced sufficiently to suit the electro
motive force at which it is intended to work. Sometimes, in order to increase the
effect of the extra current set up as above explained, I introduce into the short
circuit a large electro magnet having a very low resistance.
In order to thicken the ends of the carbonized threads so that they may be
adapted for insertion into the platinum spirals hereinbefore described, or other
holders which may be used in the lamps, I connect the two sides of the threads at
a short distance from their ends by a copper or other metal wire or clip, and I then
continue to send a current through; and as this current does not pass through the
parts of the threads beyond the wire or clip, the deposit of carbon takes place upon
and thickens the ends only.
For turning on and off the currents for lighting and extinguishing lamps; as, for
instance, a number of street lamps without lighting or extinguishing the lamps in
adjoining houses, which derive their current from the same electric main as the
street lamps, I adopt the following means:-
According to one method I connect in series by a line wire a number of street
lamps, which may be joined between the electric main and the earth. At each
lamp I fit a permanent magnet and an electro magnet capable of altering its
polarity according to the direction of a current sent through it. The coils of these
electro magnets form part of the circuit of the line wire. On sending a current
through the line wire, the movement of the magnet at every lamp in the series is

page_text: caused; through a lever or other suitable device, to turn on or off the current from
the main according to the direction of the current sent through the line wire. Or
an electro magnet acting against a spring may be employed at each lamp, the
magnets being acted upon by the current sent through the line wire. In this case
the current must be maintained as long as the lamps are to continue alight, or as
long as they are to continue unlighted, as may be arranged.
Acording to another method I employ in connection with every lamp to be
lighted or extinguished an electro magnet of very high resistance, many times
greater than that of the lamp. The circuit of this electro-magnet is always closed,
so that a feeble current is always passing through it from the main to the earth.
In connection with this magnet is a spring armature, the tension of the spring
exactly balancing the attraction of the magnet at the normal electro motive force
of the main. An increase or decrease in such force will therefore make the
armature approach or recede from the magnet. The armature is placed so that the
movement caused by a momentary increase of the electro motive force closes the
circuit of a second electro magnet, and that the movement caused by a momentary
decrease of the force closes the circuit of a third electro magnet, these two magnets
being each joined between the main and the earth. One of these magnets turns
the lamp current on, and the other turns it off when their circuits are respectively
closed. The momentary increase of the electro motive force can be conveniently
produced by the momentary introduction between the main and the earth of a
powerful secondary battery, and the momentary decrease by the sudden short
circuiting of the mains with the earth, or by a sudden check of the source of supply
of the electro motive force.
Instead of the first electro magnet in the last described arrangement, an electro-
static apparatus, such as an electrometer, may be used.
.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said St. George Lane Fox in the Great Seal Patent Office on the
18th July 1881.
ST. GEORGE LANE Fox, of Rushmore, in the County of Wilts.
"IMPROVEMENTS
IN ELECTRIC LAMPS, IN THE MANUFACTURE OF PARTS THEREOF, AND MEANS OF
TURNING ON AND OFF ELECTRIC CURRENTS FOR LIGHTING AND EXTINGUISHING
LAMPS, OR FOR OTHER PURPOSES."
My Invention consists of improvements in electric lamps, of the manufacture of
improved burners or "luminous bridges" for such lamps, and of means of turning
on and off electric currents for lighting and extinguishing lamps, as, for instance, a
number of street lamps without lighting or extinguishing the lamps in adjoining
houses which derive their current from the same electric main as the street lamps,
the said means being also applicable to turning on and off electric currents for
other purposes. The improved lamps and luminous bridges or burners, and the
means of turning on and off electric currents, may be used in conjunction with
the system of distribution and regulation of electric currents, as explained in the
Specifications of several former Letters Patent granted to me and dated respectively
9th October 1878, No. 3988; 12th October 1878, No. 4043, and 14th November
1878, No. 4626, or otherwise.
In my improved lamps I insert the ends of the luminous bridge or burner
whether made in the manner hereinafter described or otherwise, into spirals formed
of platinum wire in which they fit tightly, and in order to cement the two together
I coat the spirals and the said ends with (genuine) Indian or Chinese ink, which I
find makes a good connection, particularly after it becomes charred by the heat of
the lamp.
Figure 1 of the annexed Drawings is a vertical section of one of the improved
lamps. A is the flask or globe; a, the luminous bridge; b, b, the platinum wires;
c, c, the spirals formed at the lower ends of these wires, into which the ends of the
bridge a are inserted, and in which they fit tightly, the spirals and bridge being
cemented together with, Indian or Chinese ink as already stated. The ink is best
applied by dabbing it over and into the spirals after the ends of the bridge have
been inserted into them. I fuse the upper part of the platinum wires b, b, into
solid pieces of English lead glass d, d, which form the bottom of tubes e, e; the
upper ends of the wires extend into these tubes which contain mercury, and the
conducting wires or terminals f, f, dip into the mercury. The tubes e, e, are closed
at their upper ends by a layer of marine glue g, and a layer of plaster of Paris or
other cement g¹. The manner in which the parts of the lamp may be put together
will be understood by Figures 2, 3, and 4. Figure 2 represents the flask A as it is
blown in the first instance. It has a hole at bottom from which a tube h leads.
Figure 3 represents the piece of glass of which the mercury tubes e, e, form part;
it is hollow and is blown with the tube i at its upper part. After the platinum
wires b, b, have been fused into the solid glass parts d, d, and the ends of the
luminous bridge have been inserted into the spirals c, c, and coated with Indian or
Chinese ink the piece, Figure 3, is placed over the flask A, so that the tubes e, e,
and other parts may enter the neck of the flask, as seen in Figure 4. The glass of
the upper piece and the flask neck at their point of junction k are then united
together by blowing and fusing in the ordinary manner, and the upper piece is
then severed at about the point l. The mercury is then poured into the tubes e, e,
the copper terminals f, f, inserted, and the marine glue and plaster of Paris intro-
duced over the mercury. There now only remains to produce the requisite vacuum
in the flask, and this is effected by exhausting through the tube h; when the
vacuum has been produced the tube h is closed by fusion, as in Figure 1. The

page_text: luminous bridge is raised to a state of incandescence during the exhausting operation
by passing an electric current through it, and the exhausting is continued until
gases cease or almost cease to be given off.
The body of the flask or globe may be made either of lead glass, or of glass,
such as "German glass," which has no lead in its composition; but the part in
which the platinum wires are fused, as above described, should be of lead glass, as
without the lead the platinum and glass will not adhere together without difficulty,
and the glass is liable. to crack.
For exhausting the lamp I employ by preference the means described in the
Specification of former Letters Patent, dated 28th August 1880, No. 3494.
In order to manufacture the burners or luminous bridges for electric lamps,
I wind thread, string, or tape of flax or other vegetable fibre around a block or
piece of graphite or gas carbon of suitable shape or dimensions, such, for example,
as that shown at o in Figures 5 and 6, into which block I have previously let a
piece of steel or other metal p capable of withstanding the heat hereinafter
described. The piece of steel projects from the periphery of the block in the form
of a knife edge. To prevent the convolutions or turns of the thread, string, or tape
getting displaced, I bind them with string q. I place the block (one or more at a
time) with its convolutions of thread into a hermetically closed crucible, which
I raise to a white heat. The thread thus becomes baked; in so doing it shrinks
and each turn or convolution breaks, but as the piece of steel p acts as a cutting
edge all the convolutions break in the same line. The size of the blocks and
therefore of the convolutions and the thickness of the threads are regulated
according to the lighting power required. The baked threads are removed from
the blocks o and placed in suitable numbers in clips or holders, and immersed in
an atmosphere of coal gas or other carbon compound, while an electric current
is passed through them so as to raise them to a white heat. The baked threads
are at first of so high a resistance that it is difficult to get to pass through them an
electric current of sufficient strength to produce incandescence. I overcome this
difficulty by connecting the threads directly with a dynamo-electric machine or
other electric generator, by then momentarily short circuiting the machine and
suddenly breaking contact through the short circuit; the result of this is that the
extra current set up has so high an electro motive force as to momentarily raise the
baked threads to a state of incandescence, during which time the resistance is
diminished owing to the deposit of carbon on the surface. I repeat the operation a
number of times until a current of moderate electro motive force will raise the
threads to a white heat, and I keep up this current of moderate electro motive
force until the resistance of the threads is reduced sufficiently to suit the electro
motive force at which it is intended to work. Sometimes in order to increase the
effect of the extra curerent set up, as above explained, I introduce into the short
circuit a large electro magnet having a very low resistance.
In order to thicken the ends of the carbonized threads so that they may be
adapted for insertion into the platinum spirals c, c, Figure 1, or other holders
which may be used in the lamps, I connect the two sides of the threads at a short
distance from their ends by a copper or other metal wire or clip, and I then
continue to send a current through, and as this current does not pass through the
parts of the threads beyond the wire or clip, the deposit of carbon takes place upon
and thickens the ends only.
For turning on and off the currents for lighting and extinguishing lamps, as, for
instance, a number of street lamps without lighting or extinguishing the lamps in
adjoining houses, which derive their current from the same electric main as the
street lamps, I adopt the following means:-
According to one method, represented in Figure 7, I connect in series by a line
wire A a number of apparatus fitted one to each of the street lamps B, which may
be joined between the electric main C and the earth D. This apparatus is composed
of a permanent magnet E and an electro magnet F capable of altering its polarity
according to the direction of a current sent through it. The coils of this electro

page_text: magnet F form part of the circuit of the line wire A. On sending a current
through the line wire the movement of the magnet at every lamp in the series is
caused by coming in contact with a peg G, or by moving away from this peg, to
turn on or off the current from the main according to the direction of the current
sent through the line wire; or an electro magnet acting against a spring may be
employed at each lamp, the magnets being acted upon by the current sent through
the line wire. In this case the current must be maintained as long as the lamps
are to continue alight, or as long as they are to continue unlighted, as may be
arranged.
According to another method, represented in Figure 8, I employ in connection
with every lamp B to be lighted or extinguished an electro magnet F of very high
resistance, many times greater than that of the lamp. The circuit of this electro
magnet is always closed, so that a feeble current is always passing through it
from the main C to the earth D. In connection with this magnet is a spring
armature H, the tension of the spring exactly balancing the attraction of the
magnet at the normal electro motive force of the main. An increase or decrease in
such force will therefore make the armature approach or recede from the magnet.
The armature is placed so that the movement caused by a momentary increase of
the electro motive force closes the circuit of a second electro magnet I, and that the
movement caused by a momentary decrease of the force closes the circuit of a
third electro magnet K, these two magnets being each then joined between the
main and the earth. One of these magnets I turns the lamp current on and the
other K turns it off when their circuits are respectively closed. This is effected by
means of the bar L connected with the main C and having mounted on it an
armature M. The movement of the bar to the magnet I makes contact with the
lamp B through the peg G, while the movement of the bar to the magnet K breaks
the contact. The momentary increase of the electro motive force can be
conveniently produced by the momentary introduction between the main and
the earth of a powerful secondary battery, and the momentary decrease by the
sudden short circuiting of the mains with the earth or by a sudden check of the
source of supply of the electro motive force. N is an insulated stop to prevent
the armature M coming into contact with the magnet K, and therefore avoid the
expenditure of electro motive force which would otherwise take place through this
magnet when the lamp is not lighted. The peg G is also so placed as to prevent
the armature M coming into contact with the magnet I.
Instead of the first electro magnet in the last described arrangement an electro
static apparatus, such as a "quadrant electrometer," may be used.
Having now described the nature of my said Invention and in what manner
the same is to be performed, I declare that I claim,-
First. The mode or manner of connecting the luminous bridge or conductor to
the platinum wires in electric lamps, substantially as herein before described and
represented in Figure 1, and I claim specially the use of Indian or Chinese ink for
cementing the luminous bridge to the platinum wires, as set forth.
Second. The use in the manufacture of luminous bridges or conductors for
electric lamps of a suitably shaped block with a cutting edge, substantially in the
manner and for the purpose hereinbefore described with reference to Figures
5 and 6.
Third. The mode herein described of producing incandescence in baked threads,
strings, or tapes, when manufacturing them into luminous bridges or conductors
for electric lamps by connecting the said threads, strings, or tapes with a dynamo-
electric machine or other electric generator, by then momentarily short circuiting
the machine and suddenly breaking contact through the short circuit, repeating
the operations as often as required, as and for the purpose explained.
Fourth. The method of thickening the ends of carbonized threads, strings, or
tapes to be used as luminous bridges or conductors in electric lamps by connecting
their two sides at a short distance from their ends by a wire or metal clip and
then continuing to send a current through while they are immersed in an

page_text: atmosphere of coal gas or other carbon compound, as and for the purpose
explained.
Fifth. The means or apparatus, substantially as herein described with reference
to Figure 7, for turning on and off electric currents for lighting and extinguishing
lamps, or for other purposes.
Sixth. The means or apparatus, substantially as herein described with reference
to Figure 8, for turning on and off electric currents for lighting and extinguishing
lamps, or for other purposes.
In witness whereof, I, the said St. George Lane Fox, have hereunto set my
hand and seal, this Sixteenth day of July, One thousand eight hundred
and eighty one.
ST. G. LANE FOX. (L.S.)