IMPROVEMENTS IN AND RELATING TO DYNAMO-ELECTRIC MACHINES
Year: 1880

page_text: LETTERS PATENT to William Robert Lake, of the Firin of Haseltine, Lako, &
Co., Patent Agents, Southampton Buildings, London, for an Invention of
"IMPROVEMENTS IN AND RELATING TO DYNAMO-ELECTRIC MACHINES." A
communication from abroad by Hiram Stevens Maxim, of Brooklyn, New
York, United States of America.
PROVISIONAL SPECIFICATION left by the said William Robert Lake at
the Office of the Commissioners of Patents on the 5th April 1880.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. "IMPROVEMENTS IN AND RELATING TO DYNAMO-
ELECTRIC MACHINES." [A communication from abroad by Hiram Stevens Maxim,
of Brooklyn, New York, United States of America.]
My Invention relates to a device for regulating dynamo-electric machines in
respect to the amount of electricity generated, so as to render the electro-motive
force of the current constant at each point of consumption; it also relates to
improvements in the construction of the armature and commutator of such
machines.
Dynamo-electric machines, as they have usually been constructed heretofore,
have had no means for regulating the current, and this deficiency has constituted a
serious objection to their use for many purposes to which electricity is applied.
When the current is all used in a single circuit and for a single purpose such
machines have served the purpose reasonably well, but they do not answer where
many branches from a common circuit are used, and each requires a definite and
constant amount of current, as in plating, telegraphing, and those systems of electric
lighting where many lamps are worked in branches of the main circuit.
In plating fine goods much difficulty has been experienced from changes of
polarity as well as from variations of quantity and intensity of the current, even
where a single bath has been used in a circuit. The electricity generated in the
bath by the operation of plating is sometimes sufficient to overcome the force of
the field magnets of the machine upon any slackening of the machine's speed, and
reverse the current and the removal of a part of the articles in course of plating
frequently injures the remainder by causing too rapid a deposition of metal upon
them. It is extremely desirable in plating, telegraphy, electric-lighting, and other

page_text: applications of electricity to generate a large current at a single central point, and
distribute it as much as water and gas are distributed by mains and branches in
such a manner that the electro-motive force of the current shall not vary at any
point of consumption, however much its consumption may fluctuate. Devices of
various forms have been used for varying the resistance in the circuit to compen-
sate for changes of strength in the current, and for diverting a part of the current
upon its increasing beyond its normal strength, but these systems of regulation
involve great waste of power, and the devices employed are not sufficiently sensitive
to fluctuations in the current to act efficiently. When increased resistance is
thrown into the main circuit to compensate for a lamp or branch removed it is
obvious that the power consumed is generating the current remains the same,
whether many lamps or branches or only one or two are in use, and the power
represented by the lamps or branches not in use is wasted.
It is obvious that the regulating device should be applied to the source of supply
rather than to the current after it is generated, and it is the object of the present
Invention to provide for the dynamo-machine a regulator or governor that will
automatically control the generation of the current, so as to make the amount of
olectricity generated at all times equal to the amount required for use without
appreciable variation of intensity. I may apply this system of regulation in a
variety of ways, but according to the present Invention, so far as it concerns the
regulation of the current, I use an auxiliary machine to excite the main field-magnets
and turning the brushes of the auxiliary machine towards and from the neutral
points of their commutator by mechanism automatically controlled by a sensitive
electro-magnet in a branch of the main circuit.
Another source of difficulty in the operation of such machines has been the rapid
heating of the revolving armature and its coils from the frequent changes of polarity
of the parts and the resistance of the coils. Such heating is very objectionable, as
it impairs the efficiency of operation of the machine and injures the insulation of
the wire in the coils.
Attempts have been made to provide for a circulation of air through the armaturo
and its coils by boring holes and cutting openings of various forms in the core of
the armature by making the armature shaft hollow, with a draught of air through
it, by constructing the armature core of plates aflixed directly to the armature shaft,
and slightly separated from each other by collars with openings from the hollow
shaft into the spaces between the plates, and by applying fans and other similar
devices to the armature, but all such connections and devices have worked imper-
fectly. The holes destroy the continuity of the ring, and do not expose surface
enough to the air, and the hollow shaft does not give sufficient room for the
ingress of air, while the faus acting by centrifugal force throw out the cold air and
retain the hot on account of the difference in density.
In my improved armature the parts are so divided and arranged that thero is no
considerable unbroken mass of iron or wire at any place in the armature, but both
the iron core and the coils are divided by air-passages, and a rapid circulation of
air is kept up through such passages while the machine is in use.
Another source of difficulty in the operation of such machines arises from the
imperfect action and rapid wear of the commutator.
Such commutators are commonly made of cylindrical form, and are composed of
a series of plates or strips of conducting material, corresponding in number to the
divisions or coils of the armature, and separated from each other by insulating
material. The conducting strips have heretofor been arranged in straight lines
parallel to the axis of the cylinder, or in a spiral direction, and both these arrange-
ments are subject to serious objections. Where the strips are straight and parallel
to the axis the commutator brush often breaks contact with one strip before it
comes into contact with the succeeding one; thus there is not only an interruption
and weakening of the current, but a great increase in the wear of the commutator
by reason of the large spark produced and the consequent burning of the metal.
When the plates are arranged in spiral form this objection is overcomo, but the

page_text: shrinkage of the insulating material between them allows the pitch of the spiral to
increase, and shortens the cylinder, thus loosening the plates in their clamps.
Morcover the wear of the commutator takes place for the most part at the point
where the spark passes between the commutator strips and the brush, and as this
must always take place at the saine end where the plates are mado spiral in one
direction, one end of the commutator so constructed wears much more rapidly than
the other.
I obviate these objections by making the commutator plates of such form that
they are parallel to the axis of the cylinder on the inside, and take the direction of
a double spiral on the outside. This arrangement secures all the advantages of tho
spiral arrangement, and at the same time prevents tho working loose of the plates,
and secures an even wear for the two sides of the commutator.
The said Invention comprises the combination of a dynamo-electric machine and
a similar auxiliary machine used for exciting the main field magnets with commu-
tator brushes so mounted as to turn freely and revolve automatically relatively
to the points of maximum and minimum current on the commutator of the auxiliary
machine.
It also comprises the employment of mechanism for revolving the commutator
brushes of the auxiliary machine to and from the neutral points of its commutator,
and an electro magnet for controlling the direction of such revolution, which magnet
is thrown into and out of an electrical circuit by a shunt oporated by an electro
magnet in the main circuit or a branch thereof.
It also comprises a sector carrying the brushes, in combination with a pinion
mounted on a slinft which carries two movable discs and a friction wheel, tho said
wheel revolving continuously in the same direction, and by its engagement with the
discs causing the rotation of the brushes.
It also comprises the combination of two electro magnets, one of them being of
high resistance, and placed in a branch of the main circuit, and its armature lever
controlling the admission of an electrical current to the other magnet, and the last
named magnet being of low resistance, and operating mechanisin for increasing
and diminishing the amount of electricity generated by the main dynamo-electrio
machine.
The said Invention also comprises an armature for a dynamo-magneto-electric
machine, composed of a series of annular plates separated by air passages from each
other and from the armature shaft. These plates are formed of the best iron, and
are provided with projections which serve as pole extensions. Every alternate
plate has longer projections than the others, and is also provided with other projec-
tions for holding the wire coils. These projections are on both the outer and inner
circumferences of such plates, and are so constituted as to keep the coils separated
from each other and leave air passages between them.
The said Invention also comprises the combination of one or more coils with the
said armaturo composed of a series of annular plates.
It also comprises an armature composed of discs or annular plates having in com-
bination with such discs or plates two or more similarly shaped plates of insulating
material so constructed as to project slightly beyond the metallic parts, and support
the coils free from contact therewith.
Also the use of two or more annular plates open about the armature shaft, and
having inner and outer projections to keep the coils separated from each other, with
rods and washers thereon interposed between the plates.
The said Invention also comprises a commutator in a dynamo-magneto-electric
machine having its conducting plates so constructed and arranged as to form a
double spiral upon the outside, and to be parallel to the axis of the commutator on
the inside.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said William Robert Lake in the Great Seal Patent Office on the
5th October 1880.
66
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. IMPROVEMENTS IN AND RELATING TO DYNAMO-
ELECTRIC MACHINES." A communication from abroad by Hiram Stevens Maxim,
of Brooklyn, New York, United States of America.
My Invention relates to a device for regulating dynamo-electric machines in
respect to the amount of electricity generated, so as to render the electro-motive
force of the current constant at each point of consumption. It also relates to
improvements in the construction of the armature and .commutator of such
machines.
Dynamo-electric machines as usually constructed heretofore have had no means
for regulating the current, and this deficiency has constituted a serious objection
to their use for many purposes to which electricity is applied.
When the current is all used in a singlo circuit and for a single purpose such
machines have served the purpose reasonably well, but they do not answer where
many branches from a common circuit are used, and each requires a definite and
constant amount of current as in plating, telegraphing, and those systems of electric
lighting where lamps are worked in branches off the main circuit.
In plating fine goods much difficulty has been experienced from changes of
polarity as well as from variations of quantity and intensity of the current, even
where a single bath has been used in a circuit. The electricity generated in the
bath by the operation of plating is sometimes sufficient to overcome the force of
the field magnets of the machine upon any slackening of its speed and reverse the
current, and the removal of a part of the articles in course of plating frequently
injures the remainder by causing too rapid a deposition of metal upon them. It
is extremely desirable in plating telegraphy, electric-lighting, and other applications
of electricity to generate a large current at a single central point, and to distribute
it much as water and gas are distributed by mains and branches in such a manner
that the electro-motivo force of the current shall not vary at any point of con-
sumption however much its consumption may fluctuate. Devices of various forms
have been used for varying the resistance in the circuit to compensate for changes
of strength in the current and for diverting a part of the current upon its
increasing beyond its normal strength; but these systems of regulation involve
great waste of power, and the devices employed are not sufficiently sensitive to
fluctuations in the current to act efficiently. When increased resistance is thrown
into the main circuit to compensate for the removal of a lamp or branch it is
obvious that the power consumed in generating the current remains the same,
whether many lamps or branches or only one or two are in uso, and the power
represented by the lamps or branches not in use is wasted. It is also obvious that
the regulating device should be applied to the source of supply rather than to the
current after it is generated, and it is the object of the present Invention to provide
for the dynamo electric machine a regulator or governor that will automatically
control the generation of the current, so as to make the amount of electricity
generated at all times equal to the amount required for use without appreciable
variation of intensity. may apply this system of regulation in a variety of ways,
but according to the present Invention, so far as it concerns the regulation of the
current, I use an auxiliary machine to excite the main field magnets and turn the
brushes of the auxiliary machine towards and from the neutral points of their
commutator by mechanisin automatically controlled by a sensitive electro-magnet
in a branch of the main circuit.
Another source of difficulty in the operation of such machines has been the rapid
heating of the revolving armature and its coils by reason of the frequent changes

page_text: of polarity of the parts and the resistance of the coils; such heating is very
objectionable, as it impairs the efficiency of operation of the machine and injures
the insulation of the wire in the coils.
Attempts have been made to provide for a circulation of air through the armature
and its coils by boring holes and cutting openings of various forms in the core of
the armature by making the armature-shaft hollow with a draught of air through it,
by constructing the armature-core of plates affixed directly to the armature-shaft
and slightly separated from each other by collars, with openings from the hollow
shaft into the spaces between the plates, and by applying fans and other similar
devices to the armature; but all such connections and devices have worked
imperfectly. The holes destroy the continuity of the ring and do not expose surface
enough to the air, and the hollow shaft does not give sufficient room for the ingress
of air, while the fans acting by centrifugal force throw out the cold air and retain
the hot on account of the difference in density.
In my improved armature the parts are so divided and arranged that there is
no considerable unbroken mass of iron or of wire at any place in the armature, but
both the iron core and the coils are divided by air-passages, and a rapid circulation
of air is kept up through such passages while the machine is in use.
Another source of difficulty in the operation of such machines arises from the
imperfect action and rapid wear of the commutator.
Such commutators are commonly made of cylindrical form and aro composed of
a series of plates or strips of conducting material, corresponding in number to the
divisions or coils of the armature and separated from each other by insulating
material. The conducting strips have heretofore been arranged in straight lines
parallel to the axis of the cylinder or in a spiral direction, and both these
arrangements are subject to serious objections.
Where the strips are straight and parallel to the axis the commutator-brush
often breaks contact with one strip before it comes into contact with the succeeding
one; thus not only interrupting and weakening the current but greatly increasing
the wear of the commutator by reason of the large spark produced and the
consequent burning of the metal. When the plates are arranged in spiral form this
objection is overcome, but the shrinkage of the insulating material between them
allows the pitch of the spiral to increase and shortons the cylinder, thus loosening
the plates in their clamps.
Moreover, the wear of the commutator takes place for the most part at the point
where the spark passes between the commutator-strips and the brush, and as this
must always take place at the same end where the plates are made spiral in one
direction, one end of the commutator so constructed wears much more rapidly than
the other end.
I obviate these objections by making the commutator-plates of such form that
they are parallel to the axis of the cylinder on the inside, and take the direction of
a double spiral on the outside. This construction secures all the advantages of the
spiral arrangement, and at the same timo prevents the working loose of the plates,
and secures an even wear for the two sides of the commutator.
In the accompanying Drawings,-
Figure 1 is a plan of the top of a machine embodying this Invention.
Figure 2 is a longitudinal vertical section near the centre of the said machine.
Figure 3 shows the arrangement and connection of the wires.
Figure 4 shows the position of the commutator brushes of the exciting machine.
Figure 5 is a perspective elevation of the armature and commutator, shewing the
arrangement of the parts and the method of winding the coils.
Figure 6 is an ond view of the armature.
Figure 7 is a side view of one of the larger plates composing the armature.
Figure 8 is a similar view of one of the smaller plates.
Figure 9 is an end view of the commutator, and
Figure 10 is a view of one of the metallic sections of the said commutator.
Similar letters indicate the same parts throughout the Drawings.

page_text: A, A, A, are electro-magnets forming the magnetic field of the main machine.
The three on the left (as shown in Figure 3) have their south poles attached to a
curved piece of iron which goes nearly half around the armature, and the three on
the right have their north poles attached to a similar piece of iron diametrically
opposite.
B is an armature carrying coils of insulated wire and revolving between the field-
magnets A, A, A.
C is the commutator of the main machine. It conveys the current generated by
the revolution of the armature B through proper connections to the conductors
20 and 24.
The main field magnets are not in the main circuit, but are excited by the
smaller or auxiliary machine, of which D, D, are the field-magnets and E is the
armature.
Fis the commutator of the auxiliary machine.
G, G, are the brush-holders and H, H, are the brushes.
I, I, are arms carrying the brush-holders G, G, and affixed to a sleeve surrounding
the shaft of the machine.
J is a toothed sector affixed to the same sleovo and engaging with the bevel gear-
wheel or pinion K.
L, L, is a double disc or wheel mounted upon the shaft M which carries the gear-
wheel K. It is attached to the shaft so as to turn with it but is free to move
vertically upon it a short distance. N is a wheel mounted upon the shaft Q and
revolving between the edges of the disc L, L, so that either of them may be mado
to engage with it. The shaft Q is mounted in the bearings O, O, and is revolved
continuously in the same direction by the pulleys P and j, and the band k.
R is a lever controlling the vertical position of the discs L, L.
T is a strong clectro-magnet in the circuit of the auxiliary machine, and S is its
armature.
U is a spring applied to push up the armature end of the lever R, and V is its
adjusting screw.
is an electro magnet of high resistance placed in a branch of the main
conductors, and i is its armature.
Z is a lever carrying the armature i and having a spring a to balance the pull of
the magnet h.
The construction of the revolving armature of the machine is best shown in
Figures 5 to 8.
I usually construct the body of the armature of thin plates of iron of the form
shewn in Figure 8, and at A', in Figure 6.
These plates should be of the best annealed iron, and are provided with a series
or "lodial" projections which serve as pole extensions. Part of the plates of the
armature are made of the form shown in Figure 7, and at B³, in Figure 6. These
are provided with longer projections corresponding to the "lodial" projections of the
other plates, and also with additional projections both on the outside and on the
inside for the purpose of holding the wire of the coils in position. An armature is
constructed by placing a sufficient number of plates alongside of each other, and
fastening them together by means of pins or rods H³, H³, made of some diamagnetic
material passing through all the plates, as shown in Figure 6. The plates,
however, are not placed directly in contact with each other, but are separated by
washers upon the rods H³, H³, of about the thickness of the plates, and interposed
between ilem, or between pairs of them, so as to leave air spaces between the
plates. Where the tension of the current is very great, as in machines for supplying
electric lamps, I prefer to make the larger plates of some strong insulating material
and to use a few of them, say, one to each end, and one in the middle, and they
may be made to project so as to keep the wire at some little distance from the iron
and prevent all danger of a short circuit.
Where a current of low tension is required I prefer to make all the rings of iron,
and it is advantageous under some circumstances to use more of the larger rings, or

page_text: even to construct the whole armature of them. The manner of winding the coils
is shewn in Figures 5 and 6, where C³, C³, represent the coils wound upon the
armature and held in position by the projections on the large plates B³, so as to
leave air passages between the coils both upon the inside and upon the outside.
The armature is attached to its shaft by means of a hub with spokes fitting into
recesses in the rings, or by any other suitable device. It is important however that
the space between the armature and its shaft should be left substantially open, so
as to permit the free ingress of air, and a sufficient number of the plates shown at
B³, having the larger exterior and interior projections, should be used to keep the
coils separated throughout their entire course, so as to leave an open passage for air
between them. In order to secure the greatest advantages from this construction
the plates composing the armature should be made thin, and a considorable number
of them used.
To obviato a sharp bend at the end of the coil, and the consequent injury to the
insulation and increase of resistance, I construct the end rings of the cylinder of
half-round iron; this presents an easy curve for the wire at all points.
In other respects than those mentioned my armature is similar in construction
and operation to those which are now well known and in common uso.
The construction of the commutator is best shown in Figures 5, 9, and 10. In
Figure 10 one of the metallic plates forming the commutator is shown separately.
These plates are made straight upon the edge toward the centre of the commutator-
cylinder, but V-shaped upon the side forming the circumference, and each plate is
made thicker upon the outside, so that a cross section would be sector-shaped. The
double spiral or V-shaped arrangement of the plates at the circumference is best
shewn in Figure 5. I, I, are the metallic plates, and K³, K³, are divisions of
insulating material between them. Each plate has an arm L³ projecting radially,
to which the coils are electrically connected in the usual way. As the brushes
overlap several plates of the commutator when arranged in this way there is no
danger of interruption or weakening of the current from the brush leaving one plate
before making contact with another, and the plates do not work loose in their
clamps or wear unevenly.
The armatures and commutators of both the main and the auxiliary machines aro
constructed in the manner above described, but such construction is not essential to
the operation of the regulating device, nor is the regulating device essential to the
proper operation of the armature or commutator, as either may be applied
independently of the other to machines of various forms now in use.
The operation of the said Invention is as follows:-
Upon the revolution of the shaft the auxiliary machine, the circuit of which is
always closed, generates a current of electricity which passes through the main
field magnets, through the shunt 17, 18, or the magnet T, according as the shunt is
open or closed, and finally through the field-magnets of the auxiliary machine, as
shewn in Figure 3. When the shunt 17, 18, is open the path of the current is
from 1 to 16 inclusive, in the order of the numbers, but when the shunt is closed
the magnet T is cut out and the current follows 17, 18, instead of 5, 6, 7. The
opening and closing of the shunt is effected by the magnet h, with its armature and
lever placed in the branch 20, 21, 22, of the main circuit 20, 24. The position of
the shunt obviously determines the inagnetic condition of T, and consequently the
position of the armature S. The lever R is so arranged that when the armature S
is depressed the lower disc L is brought into contact with the friction-wheel N, and
when S is raised the upper disc L engages with N. The brush-holders G, G, are so
arranged with reference to the sector J that when the lower disc engages with N
the brushes will be turned toward the position shown in the dotted lines in Figuro 4,
while with the upper disc in contact they will be turned toward the position shewn
by the full lines in the same Figure. A stop (D' in Figure 2) prevents the sector
from turning far enough to unmesh the gearing. There are two points diametrically
opposite to each other on the cominutator, where the brushes receive no current
from the machine. It is convenient to designate these as the neutral points of the

page_text: commutator, although they correspond to the magnetic poles of the armature. The
position of the brushes when at such neutral points of the commutator is represented
by the dotted lines in Figure 4. At or about ninety degrees from these are two
points where the current of greatest power will pass to the brushes, and at which
points the latter are shown by the full lines in Figure 4; between these the current 5
varies from zero up to its greatest power, and while the machine is running at
uniform speed its current may be increased or diminished at will by changing the
position of the commutator brushes. It is evident that the magnet h effectually
controls the amount of current generated by the main machine by shifting the
commutator-brushes by the auxiliary machine, for the amount of electricity 1
generated by the main machine depends upon the degree of excitement of the field-
magnets by the current of the auxiliary machine, and that depends upon the
position of its commutator-brushes..
The magnet T is made of low resistance, so as not to weaken the current of the
auxiliary machine too much, but the magnet is made of high resistance, both to 1
prevent any considerable part of the main current from passing through it, and to
render it very sensitive to fluctuations in the strength of the main current. The
lever Z is mounted like a scale beam upon knife edge supports, and its vibrations
are kept within narrow limits by means of the screws X, Y. To make an electrical
connection between the lever Z and the conductor r I use a cup of mercury and a 2
pendent of iron directly under the centro of the lever, as this does not throw the
lever out of balance or require any appreciable power to move it. One connection
of the shunt is carried to the cup of mercury through the conductor r, and the
other to the set-screw X through the conductor p and the post d, so that the shunt
is closed when the lever Z is raised. The tension of the spring a is so adjusted by
means of its adjusting screw b that it exactly balances the pull of h when a current
of normal strength is passing, and the machine is then self-adjusting to any
fluctuations of consumption of the current. The adjustment of the spring a
determines the normal intensity of the current.
..
The particular form of the parts shown is not essential, and it is obvious that
various adjustable devices other than the spring a and lever Z may be used for
balancing the pull of the magnet h. When branches are put in between the main
conductors, or the work of the main circuit is otherwise increased, the current is
momentarily weakened very slightly, the pull of the magnet is diminished, and
the spring a draws down its end of the lever, and opens the shunt, the magnet T
being excited throws the lower disc L into gear, and revolves the brushes G, G,
toward the point of maximum current on the commutator, and the current is
strengthened until equilibrium is again established between the magnet / and the
spring a. When the work of the main circuit is diminished the reverse operation
takes place. This device is very sensitive to variations of strength in the main
current, and it acts at once with great efficiency to increase or decrease the amount
of electricity generated for at the first operation of opening the shunt; the magnet T
is thrown into the auxiliary circuit, and weakens it by increasing the resistance,
and the rapid revolution of the brushes toward the neutral points still further
weakens the auxiliary current. This not only directly decreases the power of the
Inain field-magnets, but reacts upon the auxiliary field-magnets to still further
weaken the auxiliary current and the main field. Upon closing the shunt
corresponding increments are accumulated. The electro-motive force of the current
at any point of consumption is thus kept constant by- causing the machine to
generate precisely the amount required for use. Accidental changes of polarity in
the main circuit are obviously impossible, as the magnetic field of the main machine
is independent of the main circuit.
The mode of operation of the armature, as regards the prevention of heating it, is
as follows:-Upon rapid rotation of the armature the air contained in the insterstices
of the core and the coils is thrown out by centrifugal force, and fresh cool air
continually flows in at the open ends of the cylinder to take its place, and passes
into the interior of the armature through the openings between the coils on the

page_text: inside; the air not only moves radially through the annulus, but is made to move
around in the direction of its circumference, and impinge upon all sides of the
different parts, and carry away their heat. The operation of the commutator has
already been sufficiently described.
It is obvious that the essential features of the regulating device above
described are the automatic revolution of the brushes of the auxiliary machine
relatively to the maximum and neutral points of its commutator, and the automatic
control of the direction of such revolution by the inagnet h, or its equivalent, acted
upon by the main current. The particular arrangement of the toothed sector,
friction-wheels, and magnet which I have described as used for revolving the brushes
is not essential, as various other mechanical devices may be used under control of the
magnet h for imparting a reversible revolving movement to the brushes, and I do
not wish to be limited to the particular devices shown. Other devices may also be
used in place of the magnet for opening and closing the shunt, as, for instance, a
metallic rod expanding and contracting according as more or less heat is imparted
to it by the main current; but I prefer the electro-magnet, on account of its
greater sensitiveness to changes in the strength of the current.
Having thus fully described the said Invention, as communicated to me by my
foreign correspondent, and the manner of performing the same, I wish it under-
stood that I am aware that regulators of various forms have been applied to an
electrical circuit consisting of shunts or resistance-coils operated by the heating
effects of the current upon a strip of metal placed in the circuit, or some equivalent
device; but such regulators are fundamentally different from the regulator I have
described above, for they are designed to throttle or partially divert a current
already generated, while my regulator operates directly upon the source of supply.
I am also aware that solid armatures have been heretofore constructed with the
coils wound in grooves or recesses cut in the metallic core, and that grooves and
perforations of various forms have been made in such armature-cores, both to
break up the induced currents and to provide a larger surface for the radiation of
heat; and that armature-cores have also been constructed of a series of discs hung
parallel to each other upon a central hollow shaft, and separated from each other by
collars, so as to leave openings between them, into which air may be introduced
through the hollow shaft; and I do not claim such constructions or combinations,
nor do I claim the use of an auxiliary machine for exciting the field magnets of the
main machine independently of the regulating device, but I claim,-
First. The combination of a dynamo-electric machine and a similar auxiliary
machine used for exciting the main field magnets with commutator-brushes so
mounted as to turn freely and revolve automatically relatively to the points of
maximum and minimum current on the cominutator of the auxiliary machine,
substantially as described and for the purposes set forth.
Second. A dynamo-electric machine having its field-magnets excited by a similar
auxiliary machine in combination with mechanism for revolving the commutator-
brushes of the auxiliary machine to and from the neutral points of its commutator,
and an electro-magnet for controlling the direction of such revolution, which
magnet is thrown into and out of an electrical circuit by a shunt operated by an
electro-magnet in the main circuit or a branch thereof, substantially as described.
Third. The sector carrying the brushes in combination with the pinion K, the
movable discs, and the friction-wheel revolving continuously in one direction, sub-
stantially as described for the purposes set forth.
Fourth. The combination of the electro-magnet with the electro-maguet T, the
said magneth being of high resistance and placed in a branch of the main circuit,
its armature-lever controlling the admission of an electrical current to the magnet T,
and the said magnet T being of low resistance and serving to operato imechanism
for increasing and diminishing the amount of electricity generated by the main
dynamo-electric machine, substantially as described.
Fifth. An armature for a dynamo-magneto-electric machine composed of a series of

page_text: annular plates separated by air-passages from each other and from the armature-shaft,
the said plates having outer and inner projections so constructed as to keep the coils
separated from each other and leave air-passages between them, substantially as
described.
Sixth. An armature for a dynamo-magneto-electric machine, composed of a
series of thin annular plates separated by air-passages from each other and from the
armature-shaft, a part of said plates being of the form shewn at A³, and the
remainder being of the form shown at B³, substantially as described.
Seventh. In an armature for a dynamo-magneto-electric machine composed of
annular plates with air-passages between them, projections on both the outer and
inner circumferences of such plates, so constructed as to keep the coils separated
from each other and leave air-passages between them, substantially as described.
Eighth. The combination in a dynamo-magneto-electric machine of one or more of
the coils C³ with an armature composed of a series of annular plates separated by air-
passages from each other and from the armature-shaft, the said plates, or a part of
them, having outer and inner projections so constructed as to keep the said coils
separated from each other and leave air-passages between them, substantially as
described.
Ninth. In an armature composed of discs or annular plates the combination with
such plates of two or more similarly-shaped plates of insulating material, so con-
structed as to project slightly beyond the metallic parts and support the coils free
from contact therewith, substantially as described.
Tenth. The combination in an armature of two or more annular plates open
about the armature-shaft, and having inner and outer projections to keep the coils
separated from each other with rods and washers on said rods interposed between
the plates, substantially as described.
Eleventh. A commutator in a dynamo-magneto-electric machine having its con-
ducting plates so constructed and arranged as to form a double spiral upon the
outside, and to be parallel to the axis of the commutator on the inside, substantially
as described and for the purposes set forth.
Twelfth. A cominutator for a dynamo-magneto-electric machine, having its
conducting plates arranged in the form of a double spiral, substantially as described
and for the purposes set forth.
In witness whereof, I, the said William Robert Lake, have hereunto set my
hand and seal, this Fifth day of October, in the year of our Lord One
thousand eight hundred and eighty.