IMPROVEMENTS IN ELECTRIC ARC LAMPS
Year: 1883

page_text: PROVISIONAL SPECIFICATION left by William Hopkin Akester and Robert
Mitchell at the Office of the Commissioners of Patents on the 13th October
1883.
WILLIAM HOPKIN ÅKESTER and ROBERT MITCHELL, both of Glasgow, in the
County of Lanark, North Britain, Electricians, " IMPROVEMENTS IN ELECTRIC
ARC LAMPS
"
This Invention relating to electric are lamps has for its object by improved
mechanism to effect a gradual feeding or progressive movement of the carbon or
carbons combined with an automatic device for making the carbons approach each
other when separated so far as to interrupt the light.
In carrying out the Invention a solenoid is employed the wire coils thereof being
arranged and connected according to any suitable known plan. In one modification
a hollow iron core is used and the upper carbon or its holding rod passes through it.
At the lower part of the core a loose ring encircles the carbon or its rod and at one
side engages loosely between two projections fixed to the core, whilst at the other
side there is jointed a small lever the inner end of which can act up against the
underside of the ring whilst its outer end projects so as to encounter fixed stops
when the solenoid core moves up or down. In its lowest position the solenoid core
rests on a fixed cross plate or bar through a hole in which the carbon or its rod
passes; and to the cross plate there are connected two rollers or pulleys arranged
to bear frictionally on opposite sides of the carbon or its bar. One of the friction
rollers is carried by a lever the action of which is adjusted by means of a spring
and screw, whilst a part of the lever extends so as to be acted on by the solenoid
core. When no current passes through the solenoid coils the core drops to its
lowest position and acting on the lever of the friction rollers causes these rollers to
separate and allow the carbon to descend. On the electric current passing the
core rises and first slightly tilting the loose ring so as to grip the carbon or its rod
raises the carbon so as to strike the arc. The upward movement of the core brings
its small lateral lever in contact with the upper fixed stop and this lever then
moves the loose ring into the horizontal position thereby removing its grip from
the carbon or rod. The carbon or rod is however prevented from running down
by the friction rollers. Afterwards as the arc space lengthens the core descends a

page_text: little and through the gripping ring exerts sufficient downward pressure on the
carbon or its rod to feed it gradually downwards through the friction rollers.
In another modification the carbon holder is made with a rack gearing with a
spurwheel, and a double acting pawl is arranged to act on this wheel being jointed
to a lever which is moved by the solenoid core. Fixed stops are provided in
connection with the pawl which acts on the wheel and through the wheel on the
carbon holder with similar effect to that of the loose gripping ring in the first
modification. The friction rollers are applied as in the first modification being
acted on by the lever carrying the pawl and transmitting the action of the solenoid
coil. The spurwheel may be made in one piece with or fixed- to another spurwheel
or pinion gearing with a rack on the holder of the second carbon according to a
well known arrangement for moving both carbons so as to keep the light at the
same position or nearly so.