IMPROVEMENTS IN ELECTRIC LAMPS
Year: 1879

page_text: LETTERS PATENT to William Ladd, of Beak Street, in the County of Middlesex,
Electrical Engineer, for the Invention of "IMPROVEMENTS IN ELECTRIC
LAMPS." A communication from abroad by J. Jaspar, of Liege, in the
Kingdom of Belgium.
Sealed the 4th July 1879, and dated the 8th January 1879.
PROVISIONAL SPECIFICATION left by the said William Ladd at the Office
of the Commissioners of Patents on the 8th January 1879.
WILLIAM LADD, of Beak Street, in the County of Middlesex, Electrical
Engineer. "IMPROVEMENTS IN ELECTRIC LAMPS." [A communication from abroad
by J. Jaspar, of Liege, in the Kingdom of Belgium.]
This Invention consists in a novel arrangement of apparatus for maintaining and
regulating the electric light automatically without the use of clock work. In this
lamp the holders of both the upper and lower carbon points have an advancing and
receding motion, for the purpose of bringing the points together and retracting
then to complete the electric circuit and to produce the light and regulate its
intensity. The holder of the lower carbon consists of a tube which is free to slide
vertically in guides in a metal framing. This tube is slotted longitudinally to
admit within it a portion of the periphery of a grooved pulley, to which is attached
a cord that depends therefrom into the tube, and carries at its pendent end a
weight that is free to move in the tube. This weight as its cord is wound onto the
pulley comes into contact with a stud projecting inwards from the tube, and by
this means the tubular carbon holder receives a tendency upwards. Surrounding
the lower part of this tubular carbon support is a solenoid or coil of copper wire,
one end of which is in metallic connection with the frame of the lamp, the other
end being in direct connection with the source of electricity.
When the circuit in the lamp is completed, as will bo hereinafter explained, a
current of electricity will flow through this copper coil and cause it to act like
a magnet upon the carbon holder, thereby drawing down that holder against the
supporting power of the cord and pulley. The upper carbon is secured in a
pendant holder jointed to an arm which is carried by a vertical rod which is free
to slide in a tubular socket fixed to the base frame of the lamp but insulated

page_text: therefrom. By the side of this tubular socket and parallel therewith is a mercury
tube open at its upper end to receive a rod or wire attached to the sliding rod,
which wire will dip into the mercury in the tube and maintain metallic contact
with the tube whatever may be the position of the carbon holder; a wire from
this mercury tube connects with the source of electricity, and thus when the two
carbons are brought together a current will flow through the electric lamp.
Keyed to the axle which carries the before mentioned pulley is a second pulley, say
of twice the diameter of the first, and connected with this larger pulley is a cord which
is connected to the sliding rod or support of the upper carbon in such a manner that
when the pulley axle is turned by the action of a counterweight the two carbons
will be caused to approach each other, the rate of approach being greater for the
upper than for the lower carbon. It will now be understood that when the lower
carbon is drawn down by the attractive force of the solenoid, the upper carbon will
simultaneously rise, the pullies being partially rotated by the pull of the lower
carbon holder on its cord.
As the "resistance" due to the consumption of the carbon increases the
attractive force of the solenoid will correspondingly decrease, and the carbons will
be allowed to approach each other, thus restoring the electrical resistance to its
normal state.
Should however the force of the counter weight (which gives rotation to the
pullies) exceed the attractive force of the solenoid, which would be the case on the
extinction of the light from any cause, the carbons will be instantly brought into
contact, and the current will be thereby re-established.
To prevent too sudden a movement of the holder of the lower carbon, and also to
ensure perfect metallic contact of that holder with the lamp frame, the holder is
fitted with a wire which dips into a mercury tube, and carries at its lower end a
button that is immersed in the mercury. The movement therefore of the holder in
either direction, will necessitate the lifting or lowering of the button, against which
the mercury will offer a resistance sufficient to retard slightly and steady the
starting motion of the carbon holder.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Ladd in the Great Seal Patent Office on the 8th July
1879.
11
WILLIAM LADD, of Beak Street, in the County of Middlesex, Electrical
Engineer. IMPROVEMENTS IN ELECTRIC LAMPS." A communication from abroad
by J. Jaspar, of Liege, in the Kingdom of Belgium.
This Invention relates to a novel arrangement of apparatus for maintaining and
regulating the electric light automatically without the use of clockwork. In this
apparatus the holders of both the upper and lower carbon points have an advancing
and receding motion for the purpose of bringing the points together and retracting
them to complete the electric circuit and to produce the light and regulate its
intensity.
In the accompanying Drawings Fig. 1 shews the improved lamp in side
elevation (partly in section); Fig. 2 is a transverso vertical section of the same;
Fig. 3 is a sectional plan view taken in the line 1, 2, of Fig. 1; and Fig. 4 is a
sectional plan taken in the line 3, 4, of the same Figure.
The framing of this lamp consists of a base plate A, two standards A¹ which are
bolted to the base plate, and a top plate A2 which is carried by the standards; B is
the lower carbon holder, and C the upper carbon holder, which are so connected
together by cords and pulleys that by the action of a counterweight they will be
caused to approach each other, and by the action of a solenoid they will be drawn
away from each other, such movements alternating according as the opposing forces
predominate. The holder of the lower carbon consists of a tube which is free to
slide vertically in guides formed by a tube standing up from the base plate and an
opening cut through the top plate. The lower end of this tube is made of iron to
form an armature, and it is slotted longitudinally to admit within it a portion of
the periphery of a grooved pulley D, to which is attached a cord d that depends
therefrom into the tube and carries at its pendent end a weight that is free to
move in the tubo and serves to keep the cord in tension. This weight is held in
contact with a cross pin of the tube, and the pendent cord is thus virtually secured
to the tube. This carbon holder is connected electrically with the frame of the
lamp in the manner hereinafter described. The spindle of the pulley D is mounted
on centres carried by a forked bracket attached to the underside of the top
plate A. On the same spindle is a pulloy D' of about double the diameter of the
pulley D, to which is attached a cord d' which connects with the upper carbon
holder, as will presently be explained. The pulley spindle carries also a small
barrel D, from which depends a cord d³ connected with a weighted lever d³, the
weight on which is adjustable for the purpose of effecting an equipoise between
the upper and lower carbon holders.
Surrounding the tubular guide of the lower carbon holder is a solenoid or coil of
insulated copper wire E, one end of which is in metallic connection with the frame
of the lamp, the other end being in direct connection with the source of electricity.
When the circuit in the lamp is completed, as will be hereinafter explained, a
current of electricity will flow through this copper coil and cause it to act like
a magnet upon the lower carbon holder, thereby drawing down that holder against
the supporting power of the cord d of the pulley D. The upper carbon is secured
in a pendent holder C jointed to an arm C³, which is carried by a hollow vertical
rod C. This hollow rod is free to slide in a tubular guide A³ fixed in the top
plate A of the lamp frame, but insulated therefrom. The rod C projects down
through the tubular guide and has attached to it a horizontal plate, which is
notched to receive a fixed guide rod C that prevents the swaying of the upper
carbon out of line with the lower carbon. To this plate is attached the cord d'
from the pulley D'. By the side of the tubular guide A³ and parallel therowith is
a mercury tube F, open at its upper end to receive a rod or wire pendent from the

page_text: arm C', which wire maintains metallic contact with the tube whatever may be the
position of the carbon holder. A wire from this mercury tube connects with
the source of electricity, and thus when the two carbons are brought together a
current will flow through the electric lamp.
A tendency for the carbons to approach each other is maintained by the drag
of the weighted lever d³ on the cord of the barrel Ds; this however is counter-
acted at times by the attractive force of the solenoid which draws down the
lower carbon holder, and thus through the nction of the cords and pullies before
mentioned parts the carbons. So soon however as the attractive force of the
solenoid is diminished by the consumption of the carbon points so as to be inferior
to the force of the weighted lever, the two carbons will be caused to approach
each other, the rate of approach being greater for the upper than for the lower
carbon.
From the above explanation it will be understood that when the lower carbon
is drawn down by the attractivo force of the solenoid, the upper carbon will simul-
taneously rise, the pullies being partially rotated by the pull of the lower holder
on its cord. As the resistance to the passage of the current through the lamp
due to the consumption of the carbon increases, the attractive force of the solenoid
will correspondingly decrease, and the carbons will conseqnently approach each
other, and thus restore the electrical resistance to its normal state.
Should however the force of the counterweight (which gives rotation to the
pullics) exceed the attractive force of the solenoid, which would be the case on
the extinction of the light from any cause, the carbons will be instantly brought
into contact, and the current will be thereby re-established.
To prevent too sudden a movement of the holder of the lower carbon, and also
to ensure perfect metallic contact of that holder with the lamp frame, the holder
B is fitted with a wire b which dips into a mercury tube b¹ and carries at its lower
end a button that is immersed in the mercury contained in that tube. The move-
ment therefore of the holder in either direction will necessitate the lifting or
lowering of the button, against which the mercury will offer a resistance sufficient
to retard slightly and steady the starting motion of the carbon holder.
Having now set forth the nature of the Invention of "Improvements in Electric
Lamps," as communicated to me from abroad, and explained the manner of carrying
the same into effect, I wish it to be understood that under the above in part recited
Letters Patent I claim,-
The arrangement of apparatus above described, whereby the electric light is
automatically regulated and maintained.
In witness whereof, I, the said William Ladd, have hereunto set my hand
and seal, the Eighth day of July, in the year of our Lord One thousand
eight hundred and seventy nine.
WILLIAM LADD. (L.S.)