IM- PROVEMENTS IN ELECTRIC LAMPS
Year: 1879

page_text: LETTERS PATENT to Killingworth William Hedges, of No. 25, Queen Anne's
Gate, Westminster, in the County of Middlesex, for the Invention of "IM-
PROVEMENTS IN ELECTRIC LAMPS."
Sealed the 27th May 1879, and dated the 8th March 1879.
PROVISIONAL SPECIFICATION left by the said Killingworth William Hedges
at the Office of the Commissioners of Patents on the 8th March 1879.
KILLINGWORTH WILLIAM HEDGES, of No. 25, Queen Anne's Gate, Westminster,
in the County of Middlesex. "IMPROVEMENTS IN ELECTRIC LAMPS."
According to this Invention I prepare carbon rods such as are used in clectric
lamps so as to render them partially magnetic. This I effect by attaching to the
carbons or inserting in them wires or strips of iron, or by compounding with them
a proportion of iron filings or of iron oxide or magnetic ore, or by depositing on
them a thin layer of iron. I place the carbons so prepared in tubes or other
suitable guides so that they can slide freely therein towards each other, or one may
be stationary or moved by a weight or spring, or by floatation in opposition to
gravity, whilst the other is arranged so as to descend by its own weight towards
the former. Near the carbons so mounted and at the sides thereof, I arrange the
poles of electro-magnets having their coils in the circuit of the lamp, so that when
they are excited by a strong current they attract the magnetic portions of the
carbons and thereby stop or retard their advancing motion, but when the current
in their coils is too much weakened or ceases, the attraction fails to arrest the move-
ment of the carbons. I also provide for a lateral motion of one or both of the
carbon guides, the said motion being effected by the attraction of an electro-magnet
or solenoid, the coil of which is in the circuit of the lamp. The same magnets that
act laterally on the carbons so as to impede their movement along their guides may
be so arranged that their vigorous action under the influence of a strong current
moves the guides themselves laterally so as to separate the points of the carbons, their
approach being effected by springs or counterweights when the current is weakened.
The lamp provided with one or both carbons, prepared and arranged as above
described, is operated in the following manner:-At first the points of the carbons

page_text: being in contact, the lamp is put in circuit, the electricity passing freely from the
one carbon to the other excites the electro-magnets, or the electro-magnets and the
solenoid, when the latter is used, so that the carbon points are caused to separate
and the luminous are between them is produced. At the same time, owing to the
pressure of the carbons against their guides, resulting from the attraction of the
lateral electro-magnets the onward movement of the carbon is impeded until the
distance between their points is so far increased by their waste as to reduce the
power of the electric current, thereby diminishing the attractive power of the
electro-magnets and the drag on the carbons. The carbons thus being left more or
less free to move, advance towards each other, lessening the distance between their
points, so that the electric current again becomes more powerful and capable of
impeding their farther advance. Thus the advance of the carbons to allow for their
waste is automatically regulated so as to maintain the distance of their points and
the electric force passing through them practically constant.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Killingworth William Hedges in the Great Seal Patent Office on the
5th September 1879.
KILLINGWORTH WILLIAM HEDGES, of No. 25, Queen Anne's Gate, Westminster,
in the County of Middlesex. "IMPROVEMENTS IN ELECTRIC LAMPS."
i
According to this Invention, I prepare carbon rods, such as are used in electric.
lamps, so as to render them partially magnetic. This I effect by attaching to the.
carbons or inserting in them wires or strips of iron, or by compounding with them
a proportion of iron filings, or of iron oxide, or magnetic ore, or by depositing on.
them a thin layer of iron. I place the carbons so prepared in. tubes or other
suitable guides so that they can slide freely therein towards each other, or one may.
be stationary or moved by a weight or spring, or by floatation in opposition to.
gravity, whilst the other is arranged so as to descend by its own weight towards
the former. Near the carbons so mounted, and at the sides thereof, I arrange the
poles of electro-magnets having their coils in the circuit of the lamp, so that when
they are excited by a strong current they attract the magnetic portions. of the
carbons and thereby stop or retard their advancing motion, but when the current in
their coils is too much weakened or ceases, the attraction fails to arrest the move-
ment of the carbons. I also provide for a lateral motion of one or both of the
carbon guides, the said motion being effected by the attraction of an electro-magnet
or solenoid, the coil of which is in the circuit of the lamp. The same magnets that
act laterally on the carbons so as to impede their movement along their guides may
be so arranged that their vigorous action under the influence of a strong current
moves the guides themselves laterally so as to separate the points of the carbons,
their approach being effected by springs or counterweights when the current is
weakened. The lamp provided with one or both carbons, prepared and arranged as
above described, is operated in the following manner-At first the points. of
the carbons being in contact the lamp is put in circuit. The electricity
passing freely from the one carbon to the other excites the electro-magnets, or the
electro-magnets and the solenoid, when the latter is used, so that the carbon points
are caused to separate, and the luminous are between them is produced. At the
same time, owing to the pressure of the carbons against their guides, resulting from
the attraction of the lateral electro-magnets, the onward movement of the carbons
is impeded until the distance between their points is so far increased by their waste
as to reduce the power of the electric current, thereby diminishing the attractive
power of the electro-magnets and the drag on the carbons.. The carbons thus being
left more or less free to move, advance towards each other, lessening the distance
between their points, so that the electric current again becomes more powerful and
capable of impeding their farther advance. Thus the advance of the carbons to
allow for their waste is automatically regulated so as to maintain the distance of
their points and the electric force passing through them practically constant. I also
find that in preparing the carbons by compounding them with iron oxide, as above
described, I obtain an increased intensity and improved colour in the light.
DESCRIPTION OF THE DRAWINGS.
Fig 1 represents a side view of an electric lamn according to nix Invantion. A

page_text: of A. When the lamp is put in circuit, the electro-magnets C, C, and D become
excited, the two, C, C, attracting the carbons, cause them to bear against their
respective guides, producing a frictional hold which prevents them from sliding
along them, and the magnet D attracting the armature d, causes the ends of the
carbons to separate so that the voltaic arc presents itself between them. Should
the distance between the ends of the carbons become too great owing to their con-
sumption, then the lessening of the electric power so far weakens the electro-magnets
that the carbons are left free to slide and also to approach each other. Thus the
distance of the carbons is automatically adjusted to allow for their consumption and
for variations in the electric force. A couple of springs F, which meet at their bows
with insulating material interposed between them, serve to keep the carbons from
slipping down the guides when the lamp is not in circuit, the ends of these springs
bearing on them. But when the carbons are separated by the action of the magnet
D, the springs F release them and leave them to be held by the attraction of the
magnets C, C.
Fig. 2 represents a modified arrangement in which there is one electro-magnet
arranged with its poles C, C, projecting above armatures c, c, on the two carbon
guides A and B, both of which are pivotted to the framing. The attraction of C, C,
effects the double function of causing the carbons to bear against the guides and
also of separating the ends of the carbons. The carbon guides are pressed towards
their normal position by blade springs 8, 8; Fig. 3 shows the Invention applied to
a lamp having vertical carbons. The lower carbon A is floated on mercury, which
tends to press it upwards, but the attraction of the electro-magnet C¹ operates as a
break, preventing its ascent except when the magnetic power becomes weakened.
The upper carbon B tends to descend by gravity, but is in like manner impeded by
the attraction of the electro-magnet C. The poles of C1 and C2 are extended suffi-
ciently far to remove the coils of the magnets to a safe distance from the heat of the
arc. The upper carbon guide is pivotted at and carries an armature d facing the
electro-magnet D, by which the distance of the carbons is adjusted.
Having thus described the nature of the said Invention, and in what manner the
same is to be performed, I claim,-
Governing the feeding movement of the carbons of an electric lamp by rendering
them magnetic and subjecting them to the attraction of electro-magnets that have
their coils in the lamp circuit, whereby the carbons are pressed against their guides
and have their movement more or less impeded, substantially as herein described.
In witness whereof, I, the said Killingworth William Hedges, have hereunto
set my hand and seal, this Third day of September, in the year of our
Lord One thousand eight hundred and seventy nine.
KILLINGWORTH W. HEDGES. (L.S.)