IMPROVEMENTS IN APPARATUS FOR THE PRODUCTION OF THE ELECTRIC LIGHT
Year: 1882

page_text: LETTERS PATENT to Alexander Melville Clark of the firm of A. M and
W. Clark of 53 Chancery Lane in the County of Middlesex Fellow of
the Institute of Patent Agents for an Invention of IMPROVEMENTS IN
APPARATUS FOR THE PRODUCTION OF THE ELECTRIC LIGHT Communicated
to him from abroad by Léon Gerard, Engineer, Professeur agrégé à l'école
polytechnique de Bruxelles and William. V. Bonsor, Engineer, both of Brussels
in the Kingdom of Belgium
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark
"
at the Office of the Commissioners of Patents on the 23rd December 1882.
ALEXANDER MELVILLE CLARK of the firm of A M and W Clark of 53 Chancery
Lane in the County of Middlesex Fellow of the Institute of Patent Agents
"IMPROVEMENTS IN APPARATUS FOR THE PRODUCTION OF THE ELECTRIC LIGHT
[A communication to him from abroad by Léon Gerard, Engineer, Professeur
agrégé à l'école polytechnique de Bruxelles and William. V. Bonsor, Engineer, both
of Brussels in the Kingdom of Belgium]
This invention has for its object 1 the simplification of dynamo electric
machines, the modification of their mechanical construction and general dispositions
to increase the intensity of the magnetic field and its action upon the armature by
the particular form of the pole pieces. Also to maintain the field at a determined
intensity and be able to render the field or inducing current distinct from the
exterior current without the assistance of an auxiliary dynamo. To allow in a
modified form of dynamo having several armature rings on the same shaft with
their respective collectors and under the influence of the same field magnets, of
obtaining from the same machine so constituted, currents of high and low tension
simultaneously, and distributed in different circuits. And to simplify and improve
the form of the commutators or collectors by making the contact surface plane.
The cores of the armature rings are constructed of as many segments of soft cast.
iron, as there are bobbins, each bobbin having the inner faces of its flanges or
P 27

page_text: cheeks (between which the wire forming the induced circuit is wound) parallel and
the outer faces bevelled so that when assembled together end to end in the form of
a ring their joints will be radial. They are secured to the hub and to each other
by means of screws one at each joint received in a hole formed half in the end face
of each segment, the screws being also countersunk therein flush with the periphery
of the ring. The end faces of the segments or bobbins are in contact only at the
middle portion through which the screw passes the lateral portions being rebated
or sunk so as to forin radial slots at each side to promote ventilation and check
local currents in the ring. These bobbins are entirely filled with the wire wound
upon them which is flush all round with their cheeks. The sector shape of tho
bobbins and the mode of securing them to the armature hub facilitates the removal
of any one from the ring and also presents the further advantage that the winding
on the bobbins may be done separately and by mechanical means with great
facility.
The hub is made of brass or other non magnetic material and in one or more
pieces.
The pole pieces are built up of several segments all of soft cast iron and each is a
nearly complete semi-circle of such transverse sectional form as to embrace not only
the external periphery and sides of the ring but also the greater part of its internal
periphery leaving only so much, not immediately under its influence, as is necessary
for securing the ring to the hub. The upper and interior parts of the pole pieces
are easily detached to allow of the removal of the armature ring and shaft without
disturbing the field magnets. The periphery of each pole piece has through slots
to ensure adequate ventilation.
The electromagnets forming the field, number six or more, in one or two pieces;
they are placed (when in two pieces) so that their poles of same name face each
other at opposite sides of the pole pieces which are between them the two semi-
circular pole pieces being of opposite polarity.
The bearings of the armature shaft are made adjustable in the frame of the
machine so that the shaft can always be accurately centred within the polepieces
when any deviation from this position occurs. The journal boxes being for this
purpose fitted to slide in guides in the frames with brass liners interposed to
prevent magnetic contact between the boxes and frames and supported on suitable
adjusting screwe.
The armature bobbins are wound in the ordinary way and connected to their
respective commutator blades, part of the current therein generated being utilized
in maintaining the intensity of the field and the remainder for work in the
exterior circuit. To this end and in order to make the field entirely inde-
pendent of any variations of the work in the exterior circuit the wire on the
armature bobbins may be wound in two distinct circuits, each having its own
collectors, and of different resistance the one circuit being wound next the core and
the other over it or otherwise, the whole of the current generated in one of the
circuits being utilized entirely for creating the field
When there are two or more armature rings upon the same shaft the pole pieces are
so shaped as to embrace each and all of the rings in the manner above described
The field may also be placed at each end of instead of between the six field
magnets with one or more armature rings at each end. These rings though under
the influence of the same field current may be wound with wire suitable for the
generation of currents of equal tension or of high tension in one and low tension in
the other and are provided with their respective collectors
The collectors or commutators are plane discs of non-conducting material
furnished on their face with copper strips of epicycloidal form so arranged that a
vertical diameter intersects n-2 of the strips (n being the total number of the
strips) so that there will always be a pair of bobbins passing through the neutral
region out of circuit
The collecting brushes rub by their extremities upon the same diameter of the
disc thus constructed at opposite sides of the axis one above and one below, and

page_text: they are in communication by means of elastic conductors with terminals which
may be disposed in series or in multiple are one towards another
The invention further comprises a special regulator permitting the intensity of
the field to be increased or decreased by means of variable resistances which are
brought into action as the conditions of the exterior circuit may require. It
consists of a solenoid of fine wire having a high resistance connected by one end
with one end of the field circuit wire, and by the other end to an insulated lever
carrying contact projections. This lever is connected by suitable links to the
solenoid plunger whence it derives its motion.
A series of resistance bobbins provided with mercury contact cups are so disposed
as to allow the contact projections on the lever to dip in the cups and make contact
successively at various positions of the lever. One end of the resistance wire
terminates with the last mercury cup and the other end is connected to the other
end of the field circuit wire so that when the circuit is closed by the lever pro-
jections making their contact in the mercury cups the apparatus may be said to be
in multiple arc upon the field or upon the exterior circuit. As the lever by its
position increases the resistance of this shunt by means of the mercury cups the
intensity of the field will be increased and inversely.
•
The second part of the invention relates to are lamps which are of three different
models, the first two having as characteristic feature the capability of working
steadily whilst their support may be subjected to constant vibrations
The third model has been designed in view of supplying light without
interruption during several days and without change of carbons
In the first two models the steady motion of the carbons is ensured by the
escape of a certain quantity of mercury or other suitable liquid.
The carbon pencils are placed in the ordinary way in the same vertical axis
the positive being placed above. The two carbons are supported by pistons whose
areas are in inverse ratio to the consumption of carbon and the axes of the pistons
coincide with those of the carbons
In the first arrangement the weight of the upper carbon, its holder, piston and
the links connecting them together is supported by the liquid. The liquid is
allowed to escape towards the lower piston in a regular manner thus allowing the
upper carbon to descend as it becomes consumed. The mercury or other liquid in
this way arrives under the lower piston which is carefully adjusted in its cylinder
and carries the other or negative carbon pencil the whole being raised by the
pressure of the liquid.
The regular escape of the liquid from the upper to the lower cylinder is adjusted
by means of a small cock placed in a convenient part of the tube connecting the
two cylinders.
The arc is regulated in the following manner. The upper piston is hollow and
has passing through its centre a metallic stem having near its lower end the shape
of two right cones joined by their apexes in the same vertical axis. This stem
carries at the upper part the core of a solenoid and the weight of the stem is so
adjusted that the level of the liquid coincides with the apex of the cones. The
stem, the solenoid plunger and the solenoid move with the upper carbon.
The upper part of the differential solenoid is wound with fine wire & of high
resistance and disposed in multiple are upon the main circuit. The lower part is
wound with coarse wire through which the main current passes.
The action of the coarse wire preponderating upon that of the fine, it follows
that upon a reduction of arc resistance the stem is drawn towards the bottom of
the solenoid the progressive immersion of the upper cone raising the level of the
mercury or other liquid and also the upper carbon which is floating upon the
latter.
The preponderance of action of the fine wire due to an abnormal resistance of
the arc causes the stem and cones to ascend thus causing a gradual lowering of the
mercury level and therefore of the upper carbon.
In the second arrangement of lamp the upper and lower pistons carrying the

page_text: carbons, float freely upon the mercury or other suitable liquid their areas being in
the same ratio to each other as in the former case.
There are four solenoids two of coarse wire and two of fine wire, the first being
in the main circuit and the latter in multiple arc upon it all four being secured to
the stationary part of the lamp.
The mercury or other liquid is contained in a reservoir or cylinder closed at its
lower extremity by a balanced valve which is in communication with the fine wire
solenoid plungers.
In case of an increase of arc resistance the attraction of the plungers under the
influence of the fine wire causes the opening of the balanced valve, a small quantity
of liquid is allowed to flow from under the upper piston and passing through a tube
communicating between the two cylinders thus reaches the underneath part of the
lower piston which will rise in consequence.
In case of a reduction of arc resistance the plungers under the influence of the
coarse wire will have their maximum effect and by their attraction will cause the
introduction of a tube into the liquid contained in the reservoir or cylinder thereby
raising the level of this liquid and the upper piston floating upon it, this motion
closing the balanced valve.
The two above described arrangements are what are known as focussing lamps.
The third arrangement consists of a lamp having two circular discs of carbon the
volume of which is calculated in inverse ratio of their consumption. The two discs
are placed vertically and at right angles to each other, their centres and luminous
point being in the same vertical line. The regulation of the arc is effected by the
influence of a differential solenoid upon a plunger core which communicates its
motion to a horizontal lever bearing an adjustable counterweight. The lever when
actuated by the plunger raises a clutch (through the medium of a link) the said
clutch being placed between the rods or guides that carry the upper carbon disc,
The differential
the rods or guides being free to descend when the lever is at rest.
solenoid is as usual wound with fine wire at one extremity in multiple arc upon
the main, and the other extremity with coarse wire which is traversed by the
main current. A blank space is left between the two at which place the lever
is linked to the plunger. In case of a reduction of are resistance, the action of
the coarse wire will preponderate over that of the fine wire and the plunger
will be attracted by it, raising the lever, which by that motion will expand the
clutch so that any further motion will cause it to raise the rods or guides of
In case of a reduction of arc
the upper carbon disc and the disc with it.
resistance, the action of the fine wire upon the core will preponderate and attract
it in an opposite direction, causing the clutch to release the upper carbon guides
which will then descend by its own weight.
The upper carbon disc has fixed upon its spindle a toothed wheel engaging a
rack lever pivoting upon a fixed fulcrum and in communication by means of
suitable links with another ratchet wheel fixed upon the lower carbon disc spindle.
In this way an upward motion of the upper carbon will cause a slight rotation
of the lower disc, and a downward motion a rotation of the upper disc, or
inversely.
The Invention consists further in an automatic cut off or shunt of special design
to be placed in any accessible position, its terminals being connected in multiple arc
upon those of the lamp.
The object of this instrument is to prevent the extinction of any number of
lamps through accident or otherwise from affecting the rest of the series, also to
extinguish a lamp when it is no longer required.
This shunt circuit is formed as follows:-One of the terminals is in communi-
cation with a straight electro magnet of very high resistance; this circuit is closed
upon the other terminal. The first few turns of wire upon this electro magnet are
of coarse wire, leaving a projection of this wire passing through one end of the
electro magnet the circuit being continued with fine wire to the other terminal.
In case the circuit is broken in the lamp, the whole of the current passing

page_text: through the electro magnet will magnetize its core sufficiently to attract a movable
armature lever and bring it in contact with the projection left on the magnet
circuit, the other end of the lever coming in contact with the terminal of a
resistance which communicates with the other terminal of the instrument.
From this it is easy to see that the electro magnet will be short circuited at the
point where the projection was left upon its circuit, the current passing through
the armature lever and resistance to the other terminal.
Provision is made for bringing about the same result by hand when it is
desired to extinguish a lamp without altering the condition of the dynamo, its
regulator, or the other lamps in the series, by means of an ordinary blade or lever
switch; in another position of this switch the terminals may be short circuited
exclusively of the electro magnet or resistance by bridging over the two points
derived from the terminals. When a lamp is extinguished in this manner the
regulator of the dynamo will come in action; if one is not in use, the condition of
the dynamo must be modified to keep the other lamps in the series unchanged in
intensity.
These two dispositions of cut out allow any lamps in a series to be removed
without affecting the others.
The resistance may be of copper, iron, or German silver wire wound upon any
suitable refractory substance. The frame of refractory substance upon which the
resistance is wound, forms a box in which the mechanism is enclosed, the whole
being contained in a cast iron box of open work to allow of a free circulation
of air.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Alexander Melville Clark in the Great Seal Patent Office on the
23rd June 1883.
"
ALEXANDER MELVILLE CLARK of the Firm of A, M, and W, Clark of 53 Chancery
Lane in the County of Middlesex Fellow of the Institute of Patent Agents
"IMPROVEMENTS IN APPARATUS FOR THE PRODUCTION OF THE ELECTRIC LIGHT
A communication to me from abroad by Léon Gerard, Engineer, Professeur agrégé
à l'école polytechique de Bruxelles, and William V. Bonsor, Engineer, both of
Brussels, in the kingdom of Belgium.
This Invention has for its object (a) to simplify the construction of dynamo
electric machines (b) to increase the intensity of the magnetic field and its action
upon the armature by the particular form of the pole pieces; (c) to eventually
maintain the field at a determined intensity and be able to render the field or
inducting current distinct from the exterior current without the assistance of an
auxiliary dynamo; (d) to allow in a modified form of dynamo having several
armature rings on the same shaft with their respective collectors and under the
influence of the same field magnets, of obtaining from the same machine so con-
stituted, currents of high and low tension simultaneously, and distributed in
different circuits (e) to simplify and improve the form of the commutators or
collectors by making the contact surface plane (f) to provide an apparatus which
will permit of the extinction of a lamp or the stoppage of a motor in the series
without any alteration in the condition of the dynamo machine.
In order that the Invention may be more readily understood I have illustrated
it in the accompanying drawings and will proceed to describe it with reference
thereto.
Figure 1 is a part sectional elevation of the dynamo electric machine having a
single armature ring placed between the field magnets. Figure 2 is an elevation
of one of the end frames. Figure 3 represents a transverse section of the machine
the section being taken alongside the pole pieces and the lower left hand quarter
being broken away to show the armature ring segments or bobbins. Figure 4 is a
cross section of one of the pole pieces and the enclosed portion of the armature
ring. Figure 5 is a side elevation of one of the bearings of the armature shaft.
Figures 6, 7 and 8 show details of one of the bobbins of the armature ring.
Figure 9 is a longitudinal section showing the form of the pole pieces of a
dynamo electric machine having several armature rings placed side by side upon
the same shaft. Figure 10 is an elevation and Figure 11 a part end elevation and
part cross section of another modification of dynamo having one set of field
magnets with distinct pole pieces and armature rings at their extremities.
Figures 12 and 13 are respectively an elevation and plan of the commutator or
collector. Figures 14 and 15 show a plan and elevation of an automatic shunt or
cut out. In all these Figures the same reference letters and numbers indicate the
similar parts
The armature ring (of which there may be one as in Figure 1 or two three or
more on the same shaft as in Figures 9 and 10) is constructed of as many cast iron
sector shaped segments 1 as there are bobbins in the ring. The form of these
segments is clearly shown in the detail views Figures 67 and 8 by which it will
be seen that the middle part is cut away leaving a flat core to wind the induced
wire upon, and that the form of the ends is such as to leave radial slots between
the segments to promote ventilation and check local currents in the ring, plates 2
of zinc, brass, or other non-magnetic material, being also interposed between the

page_text: abutting ends of the segments so that the segments or bobbins are magnetically
insulated from each other. These segments are screwed to the arms 3 of the hub
which is made of brass or other non-magnetic metal and keyed upon the shaft, the
screws 4 being placed at each radial joint of the segments and received in half
round recesses 4* (Figure 8) formed in the ends thereof and in the plates 2. These
screws are made of, or protected by, a sheath of non-magnetic metal. The sector
shape of the bobbins and the mode of securing them facilitates the removal of any
one of them from the ring, and also presents the further advantage that the
winding may be done separately and by mechanical means.
The field or electro magnets A may be in two sets as in Figure 1, or in one set
as in Figure 10, and when in two sets they are placed so that poles of same name
face each other. In Figure 1 they are secured between the semi-circular pieces
and the frames 9. In either case the pole pieces are built up of several segments,
and each is a nearly complete semicircle of such transverse sectional form as to
embrace not only the external periphery and sides of the ring but also the greater
part of its internal periphery, leaving only a passage for the arms of the hub, and
it results from this arrangement that all but a minimum quantity of the induced
wire will be under the immediate influence of the pole pieces and that the lines of
force of the field converge upon the whole of the induced wire. Figure 4 shows a
cross section of one of the pole pieces formed of five segments, of which those
marked 5 are fixed to the frame of the machine, whilst the external piece 6 and
the two internal pieces 7 are easily detachable by removing screws 8 to allow of
the removal of the armature ring and shaft without disturbing the field magnets.
The external peripheral portion 6 has through slots in it to ensure adequate
ventilation. When there are two or more armature rings upon the same shaft, the
pole pieces are so shaped as to embrace all the rings in the same way as shown in
Figure 9.
The armature shaft carries one or more collectors as required and is mounted in
adjustable bearings shown in Figures 1, 2 and 5 whereby the position of the
shaft can be truly adjusted to the geometrical centre of the pole pieces in
case of deviation therefrom, the bearings for this purpose being grooved at 10 to
slide on guides on the frame 9 and maintained in position by means of adjusting
screws 11,
The armature bobbins are wound in the ordinary way and connected to their
respective commutator blades, part of the current generated being utilised in
maintaining the intensity of the magnetic field and the remainder for work in
the exterior circuit, and in order to eventually make the field entirely
independent of any variations of the work in the exterior circuit, the induced
wire may be wound in two distinct circuits, each provided with its own
commutator and respectively utilised, the one for creating the magnetic field, the
other for exterior work.
The magnetic field may also be situated at the two ends of one set of magnets,
as in Figure 10, with one or more armature rings at each end encircled by pole
pieces which as well as the armature rings are constructed as before described.
These rings though under the influence of the same magnetic fields may be wound
with wire suitable for the generation of currents of equal tension, or of high
tension in the one, and low tension in the other, the several circuits being provided
with their respective collectors or commutators 13. Or the two armatures may be
connected to the same collector.
0 Each collector or commutator is a plane disc of non-conducting material
furnished on its face with copper strips so arranged that the diameter upon which
the brushes rub intersects na of the strips n being the total number of strips
and a a number of the strips left out of circuit and corresponding to the bobbins
passing through the neutral region of the magnetic field. These strips are of
5 logarithmic spiral or epicycloidal shape.
Figures 12 and 13 show details of the commutator or collector which is double
faced. 13 are the epicycloidal copper strips separated by insulating material or by

page_text: an air space, each strip corresponding with one or more bobbins of the armature
ring, and being fixed upon an insulating disc 14. The metallic brushes 15
(represented by dotted lines) rub by their extremities upon the same diameter of
the discs thus constructed at opposite sides of the axis, one above and one below,
and they are in communication by means of elastic conductors 18 with terminals
which may be disposed in series or in multiple arc towards one another. The
brushes are clamped by screws 16 in holders which are coupled together and
movable along a circular concentric guide 17, the screws 16 being in electrical
relation by the flexible ribbons 18 with the terminals of the machine and insulated
from the guide 17.
The dynamo electric machine above described is as suitable for incandescent as
for are lighting and also for the transmission of power.
Figures 14 and 15 show an apparatus whereby in case one or more of the lamps
or other apparatus in the exterior circuit should fail to work, a resistance
equivalent to that of the apparatus which has failed is immediately substituted in
the circuit preventing any alteration in the working of the other lamps or motors
in the circuit and without any alteration of the speed or load of the electric
generator. This specially intended to guard against damage to the dynamo from
the simultaneous extinction of several lamps or the stoppage of electro motors
placed in series in the exterior circuit of the dynamo machine. This apparatus is
constructed in the following manner. Its two terminals 20, 24 are connected in
multiple are upon the terminals of the lamp or electro motor of which it controls
the working. To the terminal 20 is connected the one end of a coil of coarse wire
which is wound a few times upon a soft iron core, and is soldered at the other end
to the fork 21 in which is pivoted the armature lever 22. A coil of very fine wire
is wound a great number of times around the coarse wire coil (and in the same
direction) and is connected at one end to the terminal 24 and at the other to the
contact 23 against which the armature rests by its own weight when in its normal
position. The derived current thus passes from 20 by the coarse wire to 21 thence
by the armature lever 22 to the contact piece 23 and by the fine wire to 24, If
now the circuit of the lamp or electro motor is interrupted the total current passes
through the coarse and fine wire coils for an instant thereby considerably
augmenting the magnetism of the core 19 which thereupon attracts the
armature 22 whose upper extremity thus breaks the circuit of the fine wire at 23
at the same time that its lower extremity makes contact with 25 thereby closing
the circuit through a resistance of German silver or iron wire 26 wound on
refractory plates 27 and connected at one end to 25 and at the other to terminal 24.
The current then ceases to pass through the fine wire coil which is thus put out of
reach of subsequent accidents the current passing only from 20 through the coarse
wire to 21 lever 22 contact 25 and resistance 26 (which is equivalent to the
resistance of the apparatus cut out) to the terminal 24. A lever switch 30 enables
the same operation to be performed by hand when it is required to extinguish a
lamp or stop a motor without alteration in the work of the electric generator that
is to say by turning this lever 30 to the right it can be made to cause the contact
of armature lever 22 with the contact 25, in which case the resistance is thrown
into the circuit as when the armature is operated automatically and the work of
the dynamo machine is not modified. By turning the switch lever 30 to the left it
may be made to bridge over the contact projections 28 and 29 which are
respectively connected to terminals 20 24 thus short circuiting the lamp or electro
motor and in this way modifying the work of the dynamo machine, The whole is
preferably enclosed in an open work box 31.
Having described the nature of the said Invention and the manner of performing
the same I declare that what I claim as the Invention to be protected by the
herein before in part recited Letters Patent is.
1 The general construction and arrangement of the several types of dynamo
electric machines substantially as herein described and shown in the drawings.
2nd The construction of a ring armature for dynamo electric machines of

page_text: detachable segments of the form shown magnetically insulated and secured to the
hub by screws substantially in the manner shown and described.
3rd In a dynamo electric machine arranged as herein described the construction
of the pole pieces in segments of such form as to embrace to the greatest possible
extent the internal as well as the external periphery and sides of the armature
ring or rings and yet admit of the easy removal of the ring or rings and their
shaft; substantially as described and shown.
4th The particular construction of the commutator or collector having plane
contact surfaces and epicycloidal or spiral contact strips substantially as herein
shown and described
5th The combination and arrangement of apparatus for preventing any variation
of work to the electric generator (when any lamp or motor in the external circuit
ceases to operate) said apparatus cutting out its own fine wire when it comes into
operation substantially as described and shown in Figures 14 and 15.
In witness whereof I the said Alexander Melville Clark have hereunto set
my hand and seal this twenty-third day of June A D 1883.
A
M CT ADTZ