IMPROVEMENTS IN ELECTRIC LAMPS
Year: 1882

page_text: (Void by reason of the Patentee having neglected to file a Specification in
pursuance of the conditions of the Letters Patent.)
PROVISIONAL SPECIFICATION left by the said John Grice Statter at the
Office of the Commissioners of Patents on the 9th September 1882.
JOHN GRICE STATTER, of Snapethorpe, near Wakefield, in the county of York
"IMPROVEMENTS IN ELECTRIC LAMPS
""
My invention relates to improvements in electric lamps the object of my
improvements being to ensure the gradual feeding of the carbons as they are
consumed without intermittence or irregularity, to allow the lamp to be auto-
matically cut out of circuit when the carbons are consumed and to extinguish any
lamp or lamps out of a number in series at will without interrupting the main
current.
In carrying out my invention I effect the regular feeding of the carbons in
electric lamps directly by the feed current without the intervention of clockwork
or other similar arrangement. The lower carbon holder is fixed and the upper one
is constructed of a brass or other metal rack and descends upon the lower holder by
its own gravitation. The teeth of the rack engage with those of a pinion fixed
upon a light spindle and upon this spindle the armature of a dynamo electric motor
of the continuous current type revolves. The current enters at the positive
terminal of the lamp traverses the magnets and armature of the motor and passes
through a wire or strip of metal to the framework of the lamp from which it passes
to the upper carbon holder which is in electrical communication with the frame-
work by its guides and pinion wheel. Thence the current passes through the
carbons and the arc and along the lower carbon holder which is insulated from the
rest of the lamp; from the lower carbon holder it is communicated to the negative
terminal of the lamp by a wire or strip of metal. The current passing through the
43.1

page_text: motor tends to turn the armature thereof in such a direction as to raise the upper
carbon holder the power being mechanically transmitted to it by the rack and
pinion. The force tending to bring the carbon holders, with their carbons, together
is constant as it is produced by the weight of the upper carbon holder and the
force tending to separate them is that produced by the motor and depends upon
the strength of the current passing through the motor which is the same as that
of the current passing through the arc. The maximum strength of the current
passes when the carbons are in contact, as they are when the current is turned on,
the motor has then sufficient power to raise the upper carbon holder and to
establish the arc. This causes the resistance of the arc and the current is thereby
weakened, the power of the motor is thus reduced, but is still sufficient to raise the
upper carbon and holder. The resistance of the arc increasing with its length as
the motor continues to raise the holder the strength of the current becomes reduced
as also does the power of the motor until finally a certain length of arc is reached
for which the strength of the current is only just sufficient to give the motor the
necessary power to balance the opposing force, videlicet: the gravitation of the
upper carbon holder.
By these improvements a constant equilibrium is produced and will be always
maintained so long as the current remains steady and the arc will remain at a fixed
length whatever variation may take place in the length of the carbons owing to
their consumption. Thus if by the consumption of the carbons the arc would be
made for a moment slightly longer the motor would no longer have the power to
support the upper holder; it consequently descends until the original length is
reached. This action is always going on the armature being extremely sensitive
to the decrease or increase of current because the current not only passes through
the armature but also through the electro-magnets which surround it. If the
strength of the current be suddenly increased the length of the arc will be also
increased until by its increased resistance the current passing has been reduced to
its former strength when equilibrium is again restored and the are remains at its
herein before described increased length. Thus whatever strength of current may
be sent through the lamp the strength of the current is automatically rendered
constant by the alteration of the length of the arc
If a very strong current were sent through a lamp regulated to burn with a
weak current the length of the are would become inconveniently great.
To obviate this inconvenience the lamps are supplied with a screw or other
suitable device for moving the magnets of the motor a little nearer to or farther
from the armature and as magnetic force varies inversely to the square of the
distance a very small movement suffices to increase or diminish the power of the
motor according as the arc is too short or too long.
Instead of employing one motor 1 may sometimes prefer to provide the lamp
with two motors the lamp being in other respects similar to that hereinbefore
described.
In this case the armatures of both the motors are placed on the same shaft but
when the current passes they tend to turn in opposite directions one against the
other; the current is supplied to one of the motors in a similar manner to that
herein before described and tends to separate the carbons, while the other is in
a shunt circuit to the arc and turns in such a manner as to tend to bring the
carbons together. This shunt circuit has considerable resistance introduced so that
the current passing through it shall be weak.
By this arrangement a fixed length of are will be ensured whatever be the
strength of the current sent through the lamp as equilibrium will exist between the
two opposing motors only when a certain fixed proportion of the current is passing
through each and the magnitude of the whole current is immaterial since, so long
as the arc remains at this fixed length, the proportions of current and therefore the
relative strengths of the motors remain the same-Hence with any strength of
current the length of the arc remains constant provided the current be strong
enough to maintain the arc

page_text: If it is desired to alter the length of the arc it can be done by altering the
position of the magnets by the herein before described screw arrangement
For automatically cutting an electric lamp out of circuit when the carbons are
consumed I provide the upper carbon holder at its upper extremity with a disc of
insulating material, when the carbons are nearly consumed the disc presses upon
one end of a metal projection hinged at the other end to the negative terminal of
the lamp and provided with a spring similar to that employed in a penknife to
support it. When the carbons have been consumed a little more the increasing
pressure exerted by the disc as it is carried down with the upper carbon holder
causes the projection to snap down upon the case or framework of the lamp; the
current is thus allowed to pass through the motor without traversing the arc the
upper carbon holder is wound up ready for receiving a fresh carbon and the current
continues to pass without interruption through the other lamps in the circuit.
In order to extinguish any lamp or lamps out of a number in series at will
without interrupting the main current I cause a branch current or a separate
current altogether to be sent to the lamp by turning a switch. This current
circulates round an electro-magnet the core of which is in electrical communication
with the case or framework of the lamp. Above or below this core is an iron or
steel armature, normally prevented from making contact with the core by means of
a spring and this armature is in electrical communication with the negative
terminal of the lamp When the switch is closed the current circulates round the
core the armature is attracted and inakes contact with the core and the main
current can then pass from the positive to the negative terminal without passing
through the are, the motor winds up the upper carbon holder and the light is
extinguished without interrupting the main current.
If a branch current be used to circulate round the core of the magnet a resistance
must be introduced in that circuit.