AN IMPROVEMENT IN THE PRO- DUCTION OF THE ELECTRIC LIGHT AND MEANS TO BE EMPLOYED FOR THE PURPOSE
Year: 1882

page_text: LETTERS PATENT to Osgood Gee Pritchard of Penge in the County of
Surrey, Electrician for an Invention of AN IMPROVEMENT IN THE PRO-
DUCTION OF THE ELECTRIC LIGHT AND MEANS TO BE EMPLOYED FOR THE
PURPOSE
PROVISIONAL SPECIFICATION left by the said Osgood Gee Pritchard at
the Office of the Commissioners of Patents on the 7th October 1882.
OSGOOD GEE PRITCHARD, of Penge in the County of Surrey,-Electrician, "AN
IMPROVEMENT IN THE PRODUCTION OF THE ELECTRIC LIGHT AND MEANS TO BE
EMPLOYED FOR THE PURPOSE
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My Invention relates to an improvement in the production of the electric light
whereby great steadiness is ensured, the feeding of the carbon being rendered
absolutely imperceptible.
The Invention consists in causing the carbons to be brought into contact and
separated to form the arc at such rapidly recurring intervals that by virtue of the
persistence of vision, the intermittent character of the light due to the arc shall not
be perceptible to the eye. This end is attained by imparting to the one carbon an
exceedingly rapid reciprocating motion of uniform extent in the direction of the
other carbon, which is meanwhile steadily fed up to the point of contact, the carbon
which receives this reciprocating or percussive action virtually forming an abut-
ment for the other carbon to press against, constantly as it were, so that the carbon.
will be continually fed up as fast as it is consumed, and the relation of the one
carbon to the other will therefore be to all practical intents and purposes maintained
absolutely constant.
In carrying out my Invention I may provide a small electro motor in the circuit
of the lamp and in connection preferably with the upper carbon whereby the
desired reciprocating motion may be imparted to the said carbon whilst the other
carbon is pressed up to the point of contact by the action of a weight, spring, or other
mechanical or electrical force applied in any suitable manner, and whose action may
be checked or retarded if necessary by a suitable brake, or by the friction of
surfaces sliding upon one another with a film of glycerine or other suitable liquid
between them.
Instead however of the motor other means may be employed for effecting the
make and break action as will be readily understood.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Osgood Geo Pritchard in the Great Seal Patent Office on the
7th April 1883.
"AN
OSGOOD GEE PRITCHARD of Ponge in the County of Surrey Electrician
IMPROVEMENT IN THE PRODUCTION OF THE ELECTRIC LIGHT AND MEANS TO BE
EMPLOYED FOR THE PURPOSE"
My Invention relates to an improvement in the production of the electric light
whereby perfect steadiness is ensured and the Invention consists in causing the
carbons to be brought into contact and separated at such rapidly recurring
periodical intervals that, by virtue of the persistence of vision, the intermittent
character of the light emitted shall not bo perceptible to the eye: This end is
attained by imparting to the one carbon an exceedingly rapid reciprocating motion
of uniform extent in the direction of the other carbon which is meanwhile steadily
fed up to the point of contact with the first carbon, the carbon which receives this
reciprocating or percussive action virtually forming an abutment for the other
carbon to press against. So rapid however is tlie reciprocating motion of the
abutment that the other carbon, which may be restrained by a brake, cannot
partake in or follow up this motion, and hence a make and break of contact between
the carbons is produced. Thus the other carbon will consequently be continually
fed up at a rate commensurato with the consumption or wasting away of the two
carbons, so that the relation of the one carbon to the other will therefore be to all
practical intents and purposes maintained absolutely constant.
In order that my Invention may be more readily understood, I have illustrated
in the accompanying drawing one mode of carrying it into practical effect, but I
would have it understood that I do not limit myself to the particular means shown
and described of producing the intermittent contact of the carbons, as it will be
evident that the Invention may be carried into effect by other electrical or
mechanical mechanism but the Invention extends broadly to the principle of
maintaining a constant action of making and breaking contact between the carbons,
the contact being made and broken at such rapidly recurring intervals that the
intermittence of the arc cannot be perceived.
Tho drawing represents an elevation of a lamp embodying this principle. The
lower carbon holder A receives the reciprocating motion, and to this end it is
attached to the armature B of an electro-inagnet Č placed in a shunt of the main
circuit, the armature being arranged to mako and break the shunt circuit, whereby
the olectro-magnet is alternately, magnetised and demagnetised, thereby attracting
nud releasing the armature B, the reciprocating motion thus imparted to the
armature and consequently to the lower carbon holder, being minute in extent but
exceedingly rapid, the action being in fact similar to that of an ordinary induction
coil without its secondary circuit, and the armature B playing the part of tho
vibrating hammer which makes and breaks the primary circuit of such coil. The
electro-magnet is fixed by its cores to the upper plate of the lamp frame from
which it is insulated. P N are the positive and negative terminals for the unin
leads. The terminal P is insulated from the frame and is connected by conductor p
to the lower end of the upper carbon holder D and by a fine wire with the ono coil
of the electro magnet, the other coil of which is connected by a wire with the
arinature B. The terminal N is in electrical contact with the lamp frame and is
also.connected by a fine wire with the contact spring E which is provided with an
adjusting screw c for bringing the platinum plated extremity of the spring as near
as may be required to the platinum contact piece on the underside of the armature B.
Whenever the armature falls and makes contact with this spring, the shunt circuit

page_text: is closed and the electro-magnet attracts the armature, thus immediately breaking
the shunt circuit. The suspension rods of the lower carbon holder A are fixed to
(but insulated from) the armature and slide through guide tubes a or other suitable
guides rigidly attached to the lamp frame and in electrical connection with
terminal N by the pillars (not shown) connecting the top and bottom plates of the
frame. The weight of the armature and its appurtenances is partially counter-
acted by springs b applied beneath the armature and other springs b' are applied
above the armature to adjust the balance of the parts so as to give the requisite
rapidity of motion. The springs are on short pins fixed to but insulated from the frame.
The upper carbon holder D is fixed to but insulated from the lamp frame. It is
a stationary tube containing a leather packed piston & sliding therein under the
weight of the carbon and carrying the socket d' by which the upper carbon is held.
The upper end of the tube is closed by a screw cap pierced with a pin hole for the
admission of air and protected by an outer perforated screw cap.
The piston fits air tight and the descent of the carbon is retarded by the
unbalanced atmospheric pressure, the size of the pin hole being such that the air
cannot enter quickly enough to immediately destroy the partial vacuum formed in
the tube.
Having described the nature of my Invention and the manner of performing the
same, I declare that what I claim as my Invention to be protected by the herein-
before in part recited Letters Patent is :-
1st In an electric arc lamp, 'the imparting such motion to the carbons that they
are brought into contact and separated at such rapidly recurring periodical intervals
that the intermittence cannot be perceived, as herein specified.
2nd An electric arc lamp in which a rapid reciprocating motion of minute extent
is imparted to one carbon in the direction of the other carbon, whilst the other is
steadily fed up to the reciprocating carbon so as to make intermittent contact..
therewith, substantially as specified.
3rd An electric arc lamp in which the one carbon holder is attached to the
armature of an electro magnet placed in a shunt of the main circuit, the armature
acting also as a make and break, the whole being arranged and operating substan-
tially as herein specified, for the purpose of imparting rapid reciprocating motion to
the armature and carbon holder in the direction of the other carbon.
4th In an electric lamp the combination with a lower carbon receiving rapid
reciprocating motion in the direction of the upper carbon, of an upper carbon fed
towards the reciprocating carbon by the action of gravity, subject to the retarding
action of unbalanced atmospheric pressure, substantially as herein specified.
5th An electric arc lamp constructed and operating substantially as herein.
described and shown in the drawings.
In witness whereof I the said Osgood Gee Pritchard have hereunto set my
hand and seal this sixth day of April, A.D. 1883