AN IMPROVED CONSTRUCTION OF ELECTRIC LAMP
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by John Leo Somoff at the Office of the
Commissioners of Patents on the 4th August 1882.
JOHN LEO SOMOFF 14 Huntley Street Bedford Square in the County of
Middlesex "AN IMPROVED CONSTRUCTION OF ELECTRIC LAMP
"
The object of this invention is to produce an Electric arc lamp which will give &
clear steady illuminating electric arc by a novel arrangement of apparatus which
will regulate and maintain at one even and uniform distance apart, the points
of the carbons or electrodes between which the arc is formed.
The manner of carrying the invention into practice may be thus described.
I employ as is usual with this class of Electric lamp, two Electrodes or carbons,
the upper or positive carbon is secured to an iron holder square in section, the said
carbon being connected by means of a metal band or wire with the lower carbon
holder which is constructed to slide freely in a vertical tube. The upper carbon
when no current is passing drops by its own weight into contact with and rests
upon the lower carbon supported in its sliding tube.
The mechanism producing the arc between the points of the upper and lower
carbons when the electric current is passing consists of two electro magnets one
placed near one end of an horizontal lever the fulcrum of which is placed near the
carbon holder. One arm of this lever is about three times the length of its other
arm the short arm being slightly heavier than the long arm; the said long arm of
the lever is provided at its extremity with an armature of solt iron bent in the line
of a circle which the lever would describe when oscillating; parallel to the
periphery of this segmental armature a U shaped electro magnet is supported in
the framing of the lamp, A second | shaped Electro magnet is also attached by a
pivot (on which such magnet oscillates) to the short arm of the horizontal lever
the axis of which when in its normal condition is parallel thereto and in loose
contact with the upper carbon holder. The length of the I magnet from its
supporting pivot to its point of contact with the carbon holder is much shorter and
lighter than its remaining length on the opposite side of the said pivot, so that

page_text: when the short arm of the lever supporting such magnet is raised whilst oscillating
it causes the magnet in contact with the carbon holder to turn on its supporting
pivot in an upward direction.
The current of Electricity when flowing passes first from the positive terminal of
the lamp through the coil of the magnet and then branches off and passes
through the coil of the U magnet, after which it again joins the branch of the
magnet from whence the electric current passes from the upper to the lower
carbon where it escapes through the negative terminal to the next lamp.
When the current is flowing the core of the U and magnets are magnatized
the effect of which causes the magnet U to attract its armature, and draw down
the lever supporting the magnet, the said I magnet being magnatized at the
same time as the U shaped magnet attracts the carbon holder, the simultaneous
actions thus taking place viz the attraction of the magnet to the carbon holder
and the movement given to the lever supporting such magnet by the armature of
such lever being attracted by the U magnet causes the short end of the lever to
raise the magnet which by reason of its magnetic adhesion to the carbon holder
oscillates on its supporting pivot and carries with it the carbon holder thus
establishing the arc or distance between the upper and lower carbons.
The magnet being supported by a pivot fixed to the short arm of the
oscillating lever naturally describes part of a circle with each movement of the
said lever, this circular movement by reason of the contact between the carbon
holder and magnet enables a constant pressure to be maintained between such
carbon holder and magnet.
"
In order to maintain at one even and uniform distance apart. the two carbons
when the arc is formed a shunt" of high resistance is provided, the current of
electricity flowing from the positive to the negative terminals of the lamp pass
through a helix or solenoid supported by a metal bracket projecting downwards
which is secured to and in a position at right angles to the fulcrum of the lever.
The arrangement of the solenoid and "shunt" being such that so long as the
arc is maintained at one uniform distance apart the current of the "shunt" has no
influence on the core of the solenoid.
The action of the apparatus will now be understood by the following description
Immediately the arc is established the lever supporting the magnet is in a
slanting position consequently the solenoid carried by the bracket projecting from
the fulcrum of such lever is removed from its vertical position, at this time the
slightest movement having a tendancy to further lengthen the arc increases the
resistance of the main circuit and thus reduces the current passing through the arc
and increases that flowing through the solenoid which causes it to draw its core in ;
this drawing in of the core of the solenoid transmits motion through the medium.
of a lever and suitable connections to a copper roller sliding between the poles of
the U magnet the action of which is that when the core of the solenoid is lifted
the copper wheel moves and increases the distance between the poles of the
U magnet causing the armature of the lever to diminish the attraction in inverse
proportion to the square of its distance from the U magnet, thus if the wheel
increases the distance of the poles three times the attractive force of the U magnet
is diminished nine times and the lever approaches nearer to its horizontal position
in proportion as the carbons are consumed. The | magnet being governed in its
movements by the said lever such magnet has a power much greater than what is
required to keep the carbon holder suspended even at the time the attractive force
of the magnet is at a minimum, for example as the attractive force of any
electro magnet is in direct proportion to the strength of current passing through
their coils, everything being equal it is evident that as a part only of the main
circuit is passing through the U magnet whilst almost the whole of it is passing
through the magnet, the latter is evidently stronger than the U magnet
therefore the magnet will not have its attractiveness diminished to such an
extent as not to be able to support the carbon-holder.

page_text: In the event of the magnet and its supporting lever approaching the horizontal
line and the arc is over a certain length the solenoid at the time being also in a
vertical position or in a position at right angles to the said lever, and carbon-
holder it brings its core into position for acting on a train of wheels carried by a
lever which transmits motion to a rack or friction wheel in a manner that pushes
down the carbon holder and so adjusts the arc.
The slightest or most sensative decrease in the length of the arc beyond a certain
limit (the limit to which the illuminating power of the arc is adjusted) causes the
U magnet to attract the armature of the lever so as to place such lever into a
more slanting position which causes the solenoid to loose its vertical position, the
action of which breaks the frictional contact between the train of wheels and the
carbon-holder.
The before mentioned copper wheel playing between the poles of the U magnet
has a tendancy to increase the distance between the said poles; at the time such
increase is taking place the wheel forms a break on the armature-for instance as
the copper wheel is entirely under the influence of magnatism it turns all the
more slowly as its periphery gets nearer to the poles of the magnet, hence when
the armature is lifted it slides over the periphery of the copper wheel at a speed
proportinate to the revolution of such wheel, by this arrangement jumping of the
carbon and consequent flickering of the light is prevented.
A summary of the advantages obtained by the employment of the improved
construction of lamp herein set forth may be described as follows:-
a The relative position of the U magnet and its armature combined with the
copper wheel between its poles actuated by a solenoid secures the regular
motion of feed to the carbons in a manner which prevents any flickering of the
light.
b The combination of the U magnet with the | magnet through the medium of
a horizontal lever together with a special distribution of current as described,
renders the necessary disconnection or sliding of the carbon holder over the pole
of the magnet much less frequent than in the existing systems of Electric light
regulators thus diminishing the number of critical periods when the flickering of
the light usually occurs
c The combination of the magnet with the solenoid prevents sliding of the
carbon holder over the pole of such magnet at the times when any diminution of
the current takes place the carbon in every case being fed or carried down by
positive action or force.
d The comparatively coarse motions of the armature at the end of the long arm
of the horizontal lever are reduced to the most sensative and delicate motions at
the opposite end of such lever forming the short arm supporting the magnet in
contact with the carbon holder, this sensative feeding of the carbon is owing
not only to the arrangement of the horizontal lever but also to the action of the
copper wheel between the poles of the U magnet acting on the armature.
e The attractive constancy (comparatively) of the magnet in combination with
the system of wheels in connection with the different lengths of the arms of the
horizontal lever prevents the whole arrangement being influenced by exterior
shaking or vibration.
By a simple arrangement of connecting the wires the lamp may be used either
in a circuit arranged in series or in multiple arc; if in the latter arrangement the
lamp may be used either with arc lamps only or with incondescent lamps without
the employment of separate generators.
The posibility of using the lamp in circuits supplied with strong currents of low
electric-motive force, or with currents of high tension enables any kind of generator
to be used.
A further improvements consists in providing the lamps with two sets of carbons
so arranged that when one set of carbons are consumed to a certain limit the
solenoid will act on a spring inserted in a groove made in the carbon holder so as

page_text: to release such spring which will transfer the current to the other set of carbons,
at the time the new set of carbons are inserted into working position they act by
means of a projecting finger upon the released spring so as to again place it in its
proper position in the groove
The whole of the mechanism of the lamp is contained in a cylinderical box
provided with a special arrangement of openings which will admit a weak current
of air the action of which will reduce the heat produced by the current of
electricity in the conductors and thus increase their conductivity-