IMPROVEMENTS IN APPARATUS FOR DISPLAYING AND REGULATING ELECTRIC LIGHT."
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by Sir Charles Tilston Bright at the
Office of the Commissioners of Patents on the 28th July 1881.
Sir CHARLES TILSTON BRIGHT, of 20, Bolton Gardens, in the County of
Middlesex, Knight. "IMPROVEMENTS IN APPARATUS FOR DISPLAYING AND
REGULATING ELECTRIC LIGHT."
In my Invention one of the carbons of an electric lamp is separated from the
other carbon upon the passage of an electric current through the coils of two bar
electro-magnets, which I call hereafter the separating magnets. The carbon is
fixed to a frame working in guides and carrying an armature of soft iron which is
attracted by one of the poles of the separating magnets, and is thereby moved a
sufficient distance to establish the required space between the carbons in order to
produce the luminous arc. The other poles of the separating magnets are fitted
with soft iron pole pieces which are regulated by screw adjustments, so that they
can be set with great nicety nearer to or farther from a soft iron armature which
is fixed to a lever, the axle of which works upon pivots. An adjustable spring
draws the lever away from the poles when no current is passing.
An electro-magnet, which I call the feed magnet (because the feed of one or
both of the carbons is regulated by it), is connected at one end of its coils to the
lever, the other end.being connected to a contact stop, against which the free end
of the lever rests when no current is passing, or when the current is weaker than
the tensile force of the adjustable spring.
When the carbons are drawn apart by an electric current being passed through
the separating magnets, the armature of the lever is also attracted, thereby placing
the feed magnet in circuit.
The adjustable pole pieces are so regulated that when the current through the
are gives the greatest amount of light, the free end of the lever is just held away
from the contact stop and the lever rests lightly against a retaining stop. Upon
any diminution of the force of the current the lever falls back against the contact
stop, bringing the feed magnet into action.
The lever thus acts the part of the relays used in telegraphs for opening or
closing the circuits connected with heavier apparatus, such as recording instruments,

page_text: and an ordinary relay may be used instead of the lever actuated by one of the
poles of the separating magnets.
Solenoids may be used in place of the electromagnets.
The feed is effected by a rack carrying the carbon and gearing into a short train
of wheels terminating in an escapement actuated by the feed magnet..
In another part of my Invention I use a light brake wheel instead of the
escapement, upon which a brake attached to the armature of the feed magnet
presses when the current is passing through its coils.
When it is desired to use an extra length of carbon for lamps burning many
hours, I pass the carbon through guide rollers, and the feed is effected by clips
taking hold of the carbon which are moved by the feed magnet (in the same
manner as the escapement or brake) when the relay cuts it out of circuit.
In another part of my Invention I use a wheel rotating in mercury or other
suitable fluid to retard and regulate the motion of the carbons upon the withdrawal
of a brake or detent by the action of the armature.
In another application of my Invention I cause the armature and lever (which
are actuated by the adjustable. poles of the separating nagnets) to operate directly
upon a brake wheel or detent, the said adjustable poles being so regulated that any
decrease of the force of the arc current withdraws the brake or detent.
I have described my system of rendering the action of the heavier parts used in
electric lamps more sensitive to minute differences of current by the employment
of a relay regulator in its application to are lights alone, but it can also be applied
.to electric lamps in which the light is produced at a point of contact.