IMPROVEMENTS IN MACHINES AND APPLIANCES FOR GENERATING ELECTRIC CURRENTS, AND IN APPARATUS FOR MEASURING ELECTRIC CURRENTS
Year: 1878

page_text: LETTERS PATENT to John Toby Sprague, of Bordesley Green, Birmingham, in
CC
the County of Warwick, Electrician, for the Invention of IMPROVEMENTS
IN MACHINES AND APPLIANCES FOR GENERATING ELECTRIC CURRENTS, AND
IN APPARATUS FOR MEASURING ELECTRIC CURRENTS."
Sealed the 9th May 1879, and dated the 22nd November 1878.
PROVISIONAL SPECIFICATION left by the said John Toby Sprague at the
Office of the Commissioners of Patents on the 22nd November 1878.
JOHN TOBY SPRAGUE, of Bordesley Green, Birmingham, in the County of
Warwick, Electrician. "IMPROVEMENTS IN MACHINES AND APPLIANCES FOR
GENERATING ELECTRIC CURRENTS, AND IN APPARATUS FOR MEASURING ELECTRIC
CURRENTS."
My improvements in the generation of electric currents relate to the machines
called magneto electric and dynamo-electric, in which a current is produced by the
rotation or motion of a conductor in the magnetic fields of either permanent magnets
or of electro-magnets fed by the current produced by the machine itself. Such
machines consist of two parts, one of which I call the inducing system, which
consists of either the permanent or electro-magnets, of which the polar magnetism
is always in the same direction; and the second, which I call the induced system,
consists of conductors or of electro magnets, the polar direction of which is subject
to changes. Motion may be given to either of these systems, or to both, in opposito
directions, and the whole or part of the currents set up in the induced system may
be passed through the inducing system, as is well understood.
In one type of machines the polar ends of the induced system are caused to pass
across the ends or sides of the magnets of the inducing system, or between two
opposite poles of this system, as in the "Alliance" machine, the currents being
due wholly to the magnetizing and demagnetizing of the cores of the induced
system. In machines of this type, I construct the magnetic cores of sheet iron,
wound up into a helix, with all its parts or turns electrically insulated, as is not
031

page_text: uncommon, but I make this iron coil itself a part of the electric circuit, and the
principle of this improvement I may apply to all other forms of electro magnets,
whether hereinafter mentioned or not, this principle being the utilizing of the
tendency to set up an electric current in the core itself instead of endeavouring to
resist the formation of such a current, as has been hitherto the universal practice.
Such cores or electro-magnets may therefore be constructed either of a single sheet
extending over the whole length, or in several parallel sheets, connected electrically
so as to cause the current to pass in one direction throughout, either by means of
discs at the ends, or intervals, or by means of a central rod, with or without ter-
minal disce or pole pieces, or they may consist of a coil of insulated iron wire.
This iron core and conductor may either constitute the whole electro magnet, or be
further continued in the ordinary way into a copper wire coiled in the same
direction. The ends of such electromagnets may be either open and uncovered, or
may be terminated magnetically by pole pieces, to concentrate the magnetic action,
or to connect them to each other or to other portions of the apparatus; and where
the purpose will allow of this, I prefer to make a cut or opening across the material
of such discs, such as a radial cut in a circular disc, in order to prevent the formation
of an electric current in the disc or pole piece itself.
»
In machines of the "Alliance type, which includes many different modes of
construction, and which may have an electro magnetic inducing system, though
this is usually composed of permanent magnets, there are usually an equal number
of polar faces in the two systems, each alternate one developing opposite
polarity.
As the currents in each of these magnets are alternately different, I connect cach
alternate conductor together, either in series or multiple arcs, or in groups, as is
well understood, and then I may connect these two systems together, either so as to
make a complete circuit in one direction, or I connect them together into a complete
and closed circuit with opposed forces, so that no current will pass until an external
circuit is opened, uniting the two forces in multiple arc by means of conductors from
the two points of union of the independent systems.
In either case I connect the terminals to a collector, consisting of two rings, either
cylindrical upon the shaft which gives motion, or flat and concentric upon the side
of the frame, which carries the electro magnets, insulating one or both of these
rings from the shaft or frame. Springs, brushes, or rollers, in contact with these
rings carry the currents to binding screws.
If it is desired to convert the alternating currents thus obtained into a direct
one, these rings must have spaces cut in them corresponding to the number of
magnets, so as to form a series of interlapping teeth, which will alternately make
connection from each of the rings to one or other of the collecting springs, as is
well understood.
When it is desired to divide the currents produced among several independent
circuits, there must be provided such a collecting and commutating system for each
such circuit, in which case I construct such commutators upon dises of insulating
material placed parallel to each other, and each provided with the requisite collectors
and terminals.
Or if the inducing system is movable and the induced system stationary, alter-
nating currents will be obtained from the wires of the electro-magnets without any
collector, either as one complete circuit, as before described, or from any number of
parts thereof.
When it is desired to so form several circuits from one ring, I prefer not to place
all the electro-magnets close together and equidistant, but to arrange each group of
the induced system with an interval between it and the next group, so that each
group shall be differently placed as regards the magnets of the inducing system, in
order to distribute the strains. In this case the induced system will have fewer
poles than the inducing system.
When the inducing system consists of permanent magnets, I construct these of
thin sheets or bars of steel, formed with a tongue at the end, and I combine these

page_text: "
together by means of pole pieces of soft iron or cast malleable iron, the faces of
which are grooved to correspond to and fit closely to the formed ends of the steel
plates, which may have thin slips of insulating or non-magnetic matter interposed
at intervals to form air spaces. These pole pieces, which I use also in other forms
of instruments to be described, are intended to collect the magnetism of several
such systems of plates, so as to unite two or more, and to act as either a common
pole when magnets of the same order are united together, in which case the pole
piece is a consequent" pole, or to join several magnets or electro-magnets in
regular polar order, and to serve simply as connections for uniting smaller magnets
into a larger one. They may therefore be differently formed to suit each special
case, and in some cases the true polar face, that which is to act externally, may be
formed as a projection, curved, or conical, or otherwise, as required, to direct the
magnetic force or limit its period of action. The tongues may be upon the pole
pieces, and the grooves in the parts to be joined by them. With the previously
described induced system I. employ an inducing system, composed of radial magnets,
the inner ends of which are united together at or by a cylinder, which forms them
into a series of horse-shoe magnets. I attach these radial magnets to the cylinder
either by such tongues or grooves as before described, or I forin mortice holes in the
cylinder, into which the ends of the magnetic bars may be inserted and held by
clamps screwed to the cylinder. The outer ends I connect to pole pieces, to which
are also connected the similar polar ends of horizontal magnets, which face those of
the induced system. I place such a similar inducing system on the other side also,
but with poles of opposite name, facing the same induced electro-magnets. When
only one induced ring is needed, I close the outer ends of these permanent or
inducing magnets by a ring of iron, or couple them in pairs, but if more than one
induced ring is to be employed, I furnish these further ends with pole pieces and
radial inagnets going to another cylinder or to the same cylinder of iron just as
before described, and so on with as many pairs of systems as may be desired, closing
the outer ends only, all the faces of the pole pieces of each inducing system forming
a succession of alternate north and south poles.
Instead of forming the induced system with the polar direction of the electro
magneis as described, parallel with the axis of the machine, I may arrange these
electro-magnets radially, with their inner ends connected in pairs, as horse shoes, or
all connected to a ring of iron. I may construct the cores of sheets of iron arranged
parallel and slightly separated, so as to permit air to pass among them, and forming
a conical nose piece or projection beyond the coils of wire. In this case the pole
pieces or ends of the magnets of the inducing system will be formed with a similar
sloping surface, and the magnets of the two inducing systems will be of the same
name, their poles nearly meeting over the middle of the induced ring, and their two
sloping surfaces enclosing the projecting polar ends of the electro magnets, so as to
present to them the greatest possible surface, or the polar faces of the electro
magnets may be made flat, and the faces of the magnets of the inducing system
may then be also straight, and project over and enclose the induced system.
The same arrangement of electro magnets may also be made in the disc form by
connecting them either in pairs or all to one iron ring in the plane of rotation,
in which case only one inducing system or ring will be required.
Instead of using distinct electro magnets with separate polar faces I may arrange
them in a complete circle or many-sided polygon, either forming a cylindrical ring or
with each separate magnet forining a segment of the periphery of a disc. In this
case I unite the cores or electro magnets together by such pole pieces as I have
before described, so as to form of them a complete ring. The inducing system I
form in like manner, with radial magnets and circumferential ones, united by pole
pieces, so that each pole piece will be alternately north and south itself; but that
they will be consequent poles within the complete magnetic ring, the magnets of
each adjoining pair being united to the pole pieces by ends of like polarity. As a
cousequence, similar conditions will be set up in the induced ring. The winding of
the wires may then be arranged on well understood laws, so as to draw from them

page_text: such currents as may be desired. Thus the wires may be in one complete circuit,
with a conducting wire attached at the junction of the wires of each magnet, and
these conductors combined together upon the principles previously described. Or
any even number of the magnets may constitute a group separated by an interval
from the next group in the ring, and therefore dividing tho strains upon the driving
power.
In all these different modes of placing the constituent parts of the induced and
inducing systems, the same principles of arranging the wires and leading them to cul-
lectors or to commutators will apply, as described in reference to the first arrangement.
In all these arrangements also so many distinct magnetic poles are required in
the inducing system as will be at least equal to the poles of the induced system,
and I prefer to use permanent magnets, though electro magnets may be employed,
more especially in those arrangements in which the magnetic systems form a con-
nected series of consequent magnets in the form of rings. Or permanent magnets
may be used in the radial parts and electro magnets in the rings.
When I desire to produce currents of one direction, and practically continuous, I
employ a construction of the induced system similar to that last described, and
apply it upon the system of Pacinotti, more commonly known as the gramme
system that is to say, I construct a completo magnetic circle, or in the disc forin a
many sided polygon of two or more segmental parts, united together by means of
pole pieces, which may either project outwards to the level of the wire coils, or
form an equal section with that of the other parts forming a ring, upon the whole
of which coils of wire may be placed. Or in this and the other forms described, in
which a complete alternating or continuous magnetic system is formed in the core,
instead of forming tongued ends to the several sheets of iron and uniting them by
grooved pole pieces, I may cause the several sheets of the adjoining parts to interlap
with each other and secure them all together with rivets, so as to form a chain in
which the several distinct portions or magnetic cores are links.
The effect of these modes of construction is that the several parts are readily
constructed separately, and then united by means of the pole pieces or junctions, and
the wire coils inay be prepared apart, and subsequently placed upon the magnetic
core. The separate coils are then connected into one circuit with branches at each
junction taken to a commutator, consisting of many strips of metal as in the systems
referred to, with contact pieces or brushes to take off the current at the opposite
neutral points. These neutral points will be as many in number as there are active
poles in the inducing system, as is well understood.
I construct the inducing system in like manner of distinct magnets placed with
similar poles opposed and united together by pole pieces. This is already the
arrangement in existing machines, but these magnets are in them straight, and
placed at a distance, so that only their poles are effective. But I make them in a
curved form, either as flat circles or discs, facing the induced system; or as cylin-
ders enclosing the induced system, and so that the induced system in rotating is
acted upon not only by the poles but by cutting the whole magnetic field, and when
electro magnets are used by passing the spires of the wire of these.
In order to develope the requisite magnetic power I may in some cases not form
a completely closed circle, but at the neutral points or middles of the semi-circular
or segmental magnets I may bend them back or form a continuation of them in
radial lines, as is done in their inducing systems by Siemens and others.
Or I may unite to the pole pieces other magnets across the diameter in the disc
form, and in other equivalent manners, so that the pole pieces shall concentrate in
one, the action of all the several magnets united to them.
I may add to the pole pieces of the electro-magnets of the inducing systems
plates, which, when placed between the induced and inducing systems, will spread
out the polar action, as is usually done, and will by their proximity to the coils of
the electro magnets be reinforced by the external action of the coils, and when
outside the inducing system will serve as a reservoir of magnetism, and increase the
sum of the action exerted by the poles themselves.

page_text: The commutator may be formed either as a tube on the axis of rotation, or in
discs parallel to the plane of rotation, with one contact piece for each of the con-
necting wires from the wire coils, as is usually arranged, and there will be one such
commutator for each constituent ring or independent circuit desired to be produced.
All these contact pieces are individually insulated, and I use an improved con-
struction to facilitate the replacing of the parts when worn. I use a cylinder or
disc of insulating material, and upon it I secure a number of slips of metal having
a wedge shaped space or groove cut out of their upper faces, and so arranged that
there shall be two for each contact piece, with their grooves in a direct liue.
I also arrange a series of metallic blocks with screws, to which to attach tho
conducting wires in a readily accessible manner; cach of these blocks I connect to
its two corresponding grooved slips, so that these are all perfectly connected to
each other and perfectly insulated from all others. I then fill up all spaces with
insulating material, cemented in, so as to make an even surface, or with raised ribs
of insulating material to separate the actual contact pieces. These I form of slips
of metal, provided with a wedge at their bases to slip into the fixed fittings and
make good connection thereto. Screws may be used to fix these slips in their
places in any convenient manner. I use a similar construction also in the case of
the other commutators previously referred to.
The brushes, springs, or rollers taking the current from the contact pieces are
fixed to pillars or to any suitable stationary part of the machine; or in some cases
these may revolve around the contact system, which may be fixed according as the
inducing or induced system moves.
In any of these constructions or in any machine in which there are breaks of
circuit in a commutator resulting in sparks, or in the necessity of a short circuit
forming in the contact piece so wasting energy, I prefer to cause a distinct break
of continuity and to connect the two parts of the circuit to tho two poles or plates
of a secondary battery capable of absorbing the "extra" current at break and
giving it up to the circuit at its closing.
25
The number of cells of such a battery should be such that the electro-motive
force it creates shall be in excess of that due to the steady action of the machine,
but less than that existing in the extra currents, so that the normal current cannot
pass into the battery. The two poles of this battery inake connection with the
teeth or plates of the commutator by springs or rollers so arranged that they keep
the contact up during the intervals of break in the circuit and change their own
contact at the instant that the main circuit is closed, so that the battery may then
add its force to that of the current from the machine. Or by adjusting the relative
periods of contact alternating currents may be so distributed that all those of
positive direction or the reverse may be passed into the secondary battery,
returning thence to unite with the currents of negative direction or the reverse, as
the case may be, so as to constitute an intermittent current of ouc direction to be
passed into the working circuit. Such secondary batteries should consist of so
many in series as is necessary to represent the electro-motive force generated by
the machine. As this varies with the rate of movement I use a sufficient number
adapted to the full power of the machine and an automatic commutator, to include
as many cells of the battery as may be required in the circuit. As this will always
correspond to the rate of rotation I utilize centrifugal force, generated by this
rotation to effect the changes of the number of cells in circuit. I do not confine
myself to any particular modes of applying this force, as these may be varied
indefinitely, but I may employ a vessel containing mercury, which as it rises at the
circumference and falls in the centre may be made to make or break contact with
connections suitably arranged; or I may use any ordinary centrifugal governor,
similar to those used in steam engines, or a weight upon a radial bar provided
with a resisting spring or counterpoise to move a sliding contact which shall control
the number of cells included in the circuit.
My improvements in measuring electric currents relate to two classes of
measurement:1. That of currents actually passing by means of instruments

page_text: called galvanometers. 2. That of currents which have passed, or of the quantity
of work done in a given time by instruments called voltameters. For the first
of these purposes
construct coils of wire or sheet metal in pairs, one for
each side of the zero line as usual, so as to form a chamber in which the
moving magnets can play freely. I arrange two such pairs back to back, so that
they shall have reversed inagnetic fields, as is well understood, and I mount them
either horizontally, vertically, or inclined. I construct moving magnetic systems
to play in the magnetic fields of the coils, with equal and opposite magnetic forces
fixed on one axis, as magnetic needles are commonly arranged in existing instru-
ments. But these systems I cause to derive their magnetic forces wholly from the
current itself. I arrange wires as coils, into which I cause all or part of the current
to pass as well as through the principal coils upon the principle of Weber's
dynamo-meter, from which this form differs in principle by being made in two
parts so as to generate an astatic magnetic system actuated only by equal and
opposite internal magnetic actions.
I may insert iron cores in the moving coils just described, so as to convert them
into electro-magnets; or I use soft iron needles in which magnetism is to be
induced by the current in the coils. In this case the inducing action is very feeble
at first and increases with the deflection, and this renders measurement difficult.
I therefore mount on the same axis two other similar needles, inclined at from 20
to 45 degrees on one side of the first pair, which are to be placed in the zero line
or parallel with the coils of the instrument.
This second pair are therefore magnetized first and commence the movement,
while when they reach the 90 degrees of are they tend to resist the movement.
These needles may be either arranged to work inside the coils with the others, in
which case each pair may be made of one piece of sheet iron, or they may be
placed outside of the coils, one at each end of the axis which supports them all.
Such second needles may also be employed with the electro-magnetic system. This
iron system may be supported in any ordinary way; but when wire coils are used
in the moving system I support them if horizontal by bifilar or torsion suspension,
through which the required current can be passed, or by fibres, in which case
mercury connections may be used for this purpose as is well understood. In a
vertical or inclined arrangement I use a metallic plate at each end of the axis to
support it and make connection, in which case the axis is made in two parts,
electrically insulated from each other at the middle, the ends of the wires being
connected to these two parts.
Or I employ a vertical coil of wire, which may have an iron plug at the base
and may be sheathed with iron, in which is suspended a soft iron bar to be
magnetized and drawn into the coil as is well understood.
I arrange a similar
system with reverse action causing a soft iron rod to ascend, the two rods being
connected by one suspension fibre or cord, passing over a wheel, the motion of
which gives the required indications by means of a pointer, and a similar result
may be obtained with the system in other than a vertical position. This improve-
ment consists in the use of these two systems, giving opposite polarities to the two
bars, and so producing an astatic system. Or I may employ an electro-magnet to
attract a mass of soft iron and place between these mercury contained in a com-
pressible or elastic vessel, and provided with a glass tube into which the mercury
will be forced by the pressure, and I may partly counterpoise the iron armature by
means of a conical iron weight suspended in a vessel containing mercury, and so
proportioned as to increase in weight as it is lifted out of the mercury and so
counteract the increased power of the magnet. I may graduate these upon the
system described in my Patent No. 1558, A.D. 1873. In my improvements in
instruments for measuring and recording currents which have passed in a given
time 1 avail myself of any suitable chemical decomposition. Those decompositions
in which gases are generated may be made to measure the current by combining
with the decomposition cells a meter, such as is employed in measuring gas, but
as these introduce undesirable complications I prefer to use such decompositions

page_text: as do not produce the effect known as polarization of the electrodes. I therefore
employ those actions which result in the deposition of a metal in a solution of the
same metal, such as copper, in sulphate of copper. I use two plates of the metal,
and cause each to become alternately the anode. When the unit of weight repre-
senting the unit of current desired to be employed under well understood laws has
been deposited, and I cause this change of direction of the current to be effected by
the weight of metal passed from one plate to the other, the mode in which I
prefer to effect this is to support the plates, which must be of pure metal, by spiral
springs such as are used in spring balances or in any equivalent manner. I provide
a contact point, which will be reached when the plate has attained the fixed
weight. This closes the circuit of an electro-magnet, which will then draw over
an overbalanced armature.
This armature playing between two contact points connected to the two
electrodes by means of the supporting springs, being itself connected to the
positive pole of the electric source, renders the plate with which it is connected
the anode.
The same movement may be made to transfer the connection from the negative
pole of the source to the other electrode, or a separate magnet and armature
actuated at the same time and in a similar manner to the one which effects the
described transfer of the positive connection may be employed to make the negative
connection. The same result may be attained in a variety of modes of reversing
connections well known to electricians.
Each such motion or change of circuit which represents the unit of measurement
of the current is made either by the same magnets or by a separate electro-magnet,
to nove a toothed wheel forward one step and to communicate motion to a set of
wheels such as are commonly used for similar purposes.
I may use screens or divisions in the decomposition cells to regulate the direction
of the deposit upon the electrode, and I may use plates of curved, cylindrical, or
other forin.
Or I may use cylinders for electrodes, moving on an axis, on which they may
rotate as the weight of metal deposited displaces their centre of gravity. I insert
the decomposition cell in the circuit, and I may provide it with shunts so as to
permit only a fixed portion of the current to pass through the cell upon principles
well known to electricians.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Toby Sprague in the Great Seal Patent Office on the 22nd May
1879.
JOHN TOBY SPRAGUE, of Bordesley Green, Birmingham, in the County of
Warwick, Electrician. "IMPROVEMENTS IN MACHINES AND APPLIANCES FOR
GENERATING ELECTRIC CURRENTS, AND IN APPARATUS FOR MEASURING ELECTRIC
CURRENTS."
My improvements in the generation of electric currents relate to the machines
called magneto electric and dynamo electric, in which a current is produced by the
rotation or motion of a conductor in the magnetic field of either permanent magnets
or electro magnets, fed by the current produced by the machine itself. Such
machines consist of two parts, one of which I call the inducing system, which
consists of either the permanent or electro magnets, of which the polar direction is
always in the same direction; and the second, which I call the induced system, in
which the direction of the current in the wires or the polar direction of the electro
magnets is subject to change. The inducing system is often called the field magnet
and the induced system the armature.
Motion may be given to either of these systems or to both in opposite directions
and the whole or part of the currents set up in the induced system may pass
through the inducing system, as is well understood. In the various forms of ma-
chines already constructed these two systems are arranged to act upon each other
in various manners, these variations constituting the various types of construction
in which sometimes one and sometimes another of the possible reactions of the two
systems upon each other is utilized. The aim of my improvements is to so arrange
these two systems so as to utilize as far as possible all their reactions by placing
the conductors as much as possible parallel to each other and arranging the magnets
50 that their several fields exert the greatest possible influence upon each other. In
the earliest forms of magneto electric machines the polar ends of the induced system
are caused to pass across the ends or sides of the magnets of the inducing system
or between the opposite poles of this system, as in the Alliance machine, the currents
being produced only by the magnetising and demagnatising the cores of the electro
magnets. In this case it has been essential to prevent the formation of electric
currents in the cores themselves, and these have been made of wires, split cylinders,
and other forms in which electric conduction was avoided. In machines of this
type I adopt the opposite plan and make the core itself a conductor in which the
current may circulate, and this principle I may apply to any other forms of electro
magnets, whether I hereafter mention it or not. Such cores or electro magnets may
therefore be made of a single sheet of iron of the width necessary to constitute the
electro magnet and wound up as compactly as may be with either any insulating
material, as silk or paper, between the turns; or thin strips of insulating material
may be inserted at intervals so as to form air spaces through the core.
Or two or
more such sheets may be arranged side by side in a similar manner so as together to
form the length of the core, their several ends being connected either by means of a
central rod of iron or by intermediate discs of iron otherwise insulated from the
several coils, so as to form of the whole one continuous conductor in which the
current shall circulate in the same direction throughout; or the core may be con-
structed of insulated iron wire wound similarly in a coil or helix. This iron core
may either constitute the entire magnet or it may be continued as usual into a
copper wire wound in the same direction as itself. The ends of such electro magnets
may be either open or terminated by iron disés or pole pieces to concentrate the
magnetic action, which ends may also be utilized as electric connectious, and I
prefer to make a radial cut in such discs to prevent the formation of a current in the
disc itself.
The class of machines which I have called the Alliance type usually contains an
equal number of magnetic polar faces in the induced and inducing systems, and it

page_text: consists in principle of groups such as are shewn in Fig. 1 of the Drawings, where
N, S, N, S, are the inducing systein which is composed usually of permanent
magnets, though electro magnets may be used; n, s, n, s, are the electro magnets in
which opposite polar faces are induced and in the wires of which currents are
developed which, if the winding up of the wires is alike in all, will be in alternate
directions as shown. I connect each alternate conductor together either in series or
in multiple arc and on well understood principles so as to form two circuits in
which the currents may be collected and then I may connect these two systems into
one which will then have a positive and negative end; or these two circuits being
alike in force I connect their similar ends together so as to form a closed circuit in
which, there being equal opposed forces, no current is set up unless an external
circuit, connected to the point of junction of the two circuits, is provided in which
the forces can unite to produce a current. In either case I connect the ends to a
collector consisting of two rings, either cylindrical on the shaft giving motion to the
induced system, or flat and concentric upon the frame carrying this system, insu-
lating one or both of these rings, connection to which is made by springs connected
to the terminals of the machine. If it is desired to convert the alternating currents
thus obtained into currents in one direction these rings must be divided into inter-
lapping sections alternately connecting each spring to one or other of the rings as
is well understood. Instead of collecting all the electro magnets of the induced
system into one circuit they may be divided into groups, so as to produce two or
more distinct circuits which will then require each its own collecting rings and
springs. In such cases I prefer not to make the magnet poles equal in number in
each system, but to leave a space between the groups of the induced system so that
the groups come up to the poles of the inducing system successively in order to
divide the strains. I may make the inducing system moveable and the induced
system fixed, in which case no collectors will be needed, but the wires of the several
circuits will be connected direct to the terminals of the machine.
When the inducing system consists of permanent magnets I construct these of
sheets or bars of thin steel formed with a tongue at their ends, and connect them
together in the manner shewn in Fig. 2 of the Drawings by means of pole pieces,
there shewn as P. These pole pieces, made of soft wrought or malleable cast iron,
have grooves formed in their suitable sides to fit closely to the other parts to be
joined together by them, or the wedge formed grooves may be formed in the bars, and
the pole pieces have projecting keys to fit them in some cases. These pole pieces
will be formed in many different ways, and may have their active or true polar faces
formed in projections in any manner required to direct their magnetic influence
externally, and they form an important part of any Invention, as they are intended
to collect the magnetism of several systeins of magnets, so as to unite two or more
and serve as a common pole when magnetic poles of the same order are joined
together by them, in which case the pole piece is a "consequent" pole, or to join
several magnets or electric magnets in successive polar order when they serve simply
as connections. I use them both in the inducing and the induced systems, and in
the latter they enable annular systems of electro magnets to be constructed in
segments easily wound with their wires and then built up into complete rings by
means of these pole pieces.
With induced systems such as belong to the Alliance type I employ an inducing
system such as is shewn in principle in Fig. 3, composed of radial magnets, the
inner ends of which are united together at or by an iron cylinder or boss, which
forms them into a series of horse shoe magnets. This connection may be made
either by tongues and grooves, as described, or by means of brackets, or in any suitable
manner. The outer ends I connect to pole pieces, shewn as P', P, P, to which are
also connected the polar ends of magnets, which will form a circle if they are curved
as shewn, but which if straight will form a many sided polygon. These magnets
are so arranged that the several pole pieces while acting as consequent" poles
within the system collect and direct the whole of the magnetic actions externally
as alternate south and north magnetic poles. It is evident that these magnets may
"

page_text: be electro magnets, and the same remark applies to forms yet to be described, as the
only requirement is a cominutator to form the alternating currents into currents of
one direction, which can be passed into the electro magnets. I place a similar
system on the other side of the induced system, with poles of opposite names
opposed so as to produce the conditions shewn in Fig. 1, which may be regarded as
portion of all these circular systems spread out in a line. In this and similar cases
the pole pieces of the two inducing systems may be further connected by horse shoe
magnets so enclosing the induced system. If several such complete systems are
desired to be driven from one shaft the outer faces of the pole pieces may be fitted
with straight magnets forming a connection to another inducing ring, as shewn
Fig. 1 in dotted lines, or to increase the power such magnets may be used with a
single induced system, their outer ends being all united either to a ring of iron or
to another ring of pole pieces and magnets. The electro magnets of the induced
system may be connected in pairs at one end, or all fixed on an iron ring or disc so
as to present only one set of polar ends to the inducing system, which will then
consist of only a single ring of magnets as described. Instead of forming the
induced system of electro magnets placed parallel with the axis of motion, I may
arrange them radially so as to form a series of pairs like the magnets N, S, 1, 2, 3,
in Fig. 3, and I may construct them of sheets of iron slightly separated, so as to
permit air to circulate, either forming the sheets themselves or terminating them
with a pole piece of a conical section, as shewn in Fig. 4, so that the pole pieces of
the induced system (which will then have similar poles arranged opposite to each
other) may enclose the electro magnets as shewn in the Drawing. Or the polar
ends may be otherwise formed as rectangles or as half circles or otherwise, so as to
obtain a similar result.
Instead of forming the induced system of distinct electro magnets with free polar
ends I may form them into a series of segments of a circle, either as a cylinder or
as the periphery of a disc or of a many sided polygon. If we remove the radial
bar 2 in Fig. 3 and raise the two inner ends of bars 1 and 3 it is evident that the
circle formed in this manner really represents the horse shoe or radial magnets of
the form last described so straightened out as to form the system of consequent
poles intended to be produced in the modification now being described, when the
several ends of the magnets come under the pole pieces of the inducing systems.
Fig. 5 shews such an arrangement, in which S is a pole piece of the induced system
passing between the pole pieces P, P, of the inducing system so formed as to nearly
enclose the moving ring, which is thus placed nearly in the conditions of an iron
rod or a helix passing through a coil carrying a galvanic current. This is shewn
further in Fig. 6, which represents two segments of the induced system, 1 shewing
the iron core and 2 the wire. In the position shewn a powerful current of magnet-
isation and demagnetisation occurs as the induced pole pieces approach to and
recede from the inducing poles. The wires are also cutting the lines of force of the
pole pieces, and also of the magnetic bars of the inducing system, which are close
to them, and which may if desired be attached to the whole section of the pole
piece P, as shewn in Fig. 5.
In machines upon this principle I do not confine myself to induced rings built up
out of separate segments, as continuous rings may be employed composed of sheets
of iron or discs of malleable cast iron, with the suitable pole pieces formed upon
them, but I do not claim the construction of these or their use except in the par-
ticular arrangements shewn in the Drawings, or in connection with inducing systems
such as I have described.
In all arrangements of the two systems so far described as many distinct external
acting poles or pole pieces are required in the inducing system as in the induced, so
divided that all the corresponding poles oppose each other at the same time, or else
the induced system may have fewer poles so as to permit it to be divided into
groups each of which successively opposes the inducing poles. The winding of the
wires upon the induced system and the connections among the various sections will
be arranged upon well understood principles in order to effect the same results as

page_text: are already described so as to combine the wires of the whole ring or of a group of
segments into one circuit or into two circuits with opposed forces united into one,
as before described; also in all of them the same kind of arrangement will be used
for collecting the currents, as described.
When I desire to produce currents in one direction and practically continuous, I
employ a construction of the induced system similar to that last described and apply
it upon the system of Pacinotti, more commonly known as the Gramme system, that is
to say, I construct a complete magnetic circle (or in the disc form a many sided
polygon) of two or more segments united together by means of pole pieces which
may either project outwards to the level of the wire coils, or form an equal section
with that of the other parts, forming a ring, upon the whole of which coils of wire
may be placed. When the core is composed of layers of sheet or malleable cast
iron, instead of forming them so as to be united by pole pieces the several segments.
may be formed with their ends representing their pole pieces, and so that these ends
may interlap with each other so as to form air spaces, as shewn in Fig. 7. When
this ring is of a disc form so that the wires cannot entirely cover it, I fill up the
spare spaces with pieces of iron, shewn as B, B, in Figs. 2 and 7, forming corres-
ponding projections on the plates of the core, also in order to produce a series of
reels or grooves in which the wire can be wound, while the projecting pieces of
iron constitute subordinate or intermediary polar pieces. But as such grooves or
spaces or iron projections have been employed already I do not claim thein as part
of my Invention when used in the induced system or armature; but I form the
inducing system also upon the same principles in some cases, as will be hereafter
described, and the same mode of construction with the requisite modifications as to
size may be employed in both systems. The projecting pieces B, B, as shewn
Figs. 2 and 7 may be separate pieces of iron, and may be secured to the outer plates
or there may be pins passed through the block and plates to secure then all
together; slips of insulating material may be placed between the various plates
under the spaces A, A, and cemented to the plates, or wooden pins may be passed
through them all to hold the parts together. The object of this construction is to
obtain a core in which there is little electric conduction around the core itself and
also to provide air passages through the core so that when the ring is rotating a
current of air shall be set up by the rotation, as shewn by arrows in Fig. 2, similar
currents of air being produced in the stationary inducing system of smaller con-
struction by the heat itself. The wires are wound upon the core in sections, and
from each section a conductor is taken to a plate of the commutator, as is already
done in the systems of Gramme and others. The whole of the wire may be con-
nected up as one circuit, or the ring may be divided into several sections according
to the number of active poles in the inducing system, as is well understood, the com-
mutator being provided with a pair of contact springs at the neutral points, either
of the whole circuit or of each sectional circuit, as the case may be.
I construct the inducing system in like manner of distinct magnets or electro
magnets with similar poles opposed and connected by pole pieces to direct their
combined action towards the moving armature. This is already the arrangement
in existing machines, but these magnets are in them straight, except in the small
machines with large horse shoe permanent magnets and placed at a distance, and so
arranged that they act only by the magnetic influence of their poles, and in many
cases the arrangement of the wires is such as to reduce the effective result by their
nutual actions. But I make these magnets in a curved form, either as flat circles
or discs placed parallel with the induced system, or as a cylinder enclosing this
system, or as both together, so that the induced system is acted upon not only by
the poles but by traversing the whole magnetic field, and also by the current in the
spires of the wire of electro magnets when these are used. Figures 8 and 9 shew
the arrangement of the several systems in a machine; Fig. 8 is a side view shewing
the inducing system; A is a ring constructed as described, in which the shaded
parts represent the iron projections shewn in larger size B, Fig. 2. At each side of
the horizontal diameter there are pole pieces P, P, which take the place of one or

page_text: more of the wire spaces in order to produce a massive pole. To these pole pieces
are secured the heads of electro magnets N, S, which constitute with the iron base
a horse shoc magnet supporting the inducing system. These magnets are for con-
venience shewn upright and are so made in small machines, but they may be made
semicircular with advantage and may be completed with another semi circular
magnet, as shewn in dotted lines. The winding of the wires is so arranged as to
convert the pole pieces into powerful N and S poles; Figure 9 shews two discs
A, A, connected together by these electro magnets with the induced disc B between
them. Motion is given to the induced system by a shaft, not shewn, but to which it
is attached by means of the projections « on the pole pieces P, Figure 2, or in any
convenient manner. I may join to the pole pieces of the inducing system horns or
plates of iron as is usually done to spread the magnetic action when they are
inserted between the inducing and induced systems, and which when attached to
the outer side serve as reservoirs of magnetism and take up the external actions of
the current so as to cause these also to contribute to the power of the pole pieces.
Several induced rings may be arranged on one axis, with inducing rings alternating,
or they may constitute a lengthened cylinder enclosed by a cylindrical electro magnet,
either alone or with a disc at each end.
The commutator may be formed either as a cylinder on the axis of rotation, or
on discs parallel to the plane of motion with one contact piece for each of the
connecting wires from the coils of wire as is usually arranged, and there will be
one such commutator for each constituent ring or independent circuit desired to be
produced. All these contact pieces are individually insulated, and I use an
improved construction to facilitate the replacing of the exposed parts when worn.
This construction is shewn, Figures 10 and 11. a is part of the insulating cylinder
in which grooves are cut, as shewn b. In these grooves are inserted pieces of
metal formed as shewn by c, consisting of a block at one end drilled with a hole in
which the conducting wire is to be secured, and also a vertical groove into which
the end of the contact pieces e is inserted. A space is filed out towards the other
end to receive the piece d, which may be soldered in its place; these pieces d are
secured to the insulating cylinder as shewn in plan Fig. 11, so as to be separated
from each other, and these parts being secured in place, the insterstices may be
filled with ebonite, wood, &c., to make all secure. The pieces e are next slipped
into the grooves thus formed for them, so as to form the actual wearing surfaces,
and may be secured in place by the plate f. A similar construction of commutator
may be applied to the machines already described when the currents are to be
collected into a direct current.
The current is taken up in the usual manner by springs, brushes, or rollers fixed to
any suitable part of the machine, or these may revolve around a fixed commutator
if the motion is imparted to the inducing system.
In any of these constructions or in any dynamo-electric machine in which there
arc breaks of circuit in a commutation resulting in sparks, or in the necessity of
forming a short circuit in the contact piece so wasting energy, I prefer to cause a
distinct break of continuity and to connect the two parts of the circuit, that is to
say, the separate plates of the commutator to which the wires are connected or the
wires themselves, to the poles of a secondary battery capable of absorbing the
"extra" current at break, and giving it up to the circuit at its closing. The number
of the ceils in series should be such that the electro-motive force it creates shall be
in excess of that due to the steady action of the machine, but less than that
existing in the extra currents. As these vary with the rate of motion, I use a
number adapted to the highest speed of the machine, and I utilize centrefugal action
generated by the motion to control the number of cells in circuit at any time. I do
not confine myself to any special mode of applying this agency as these may be
varied indefinitely, but I may employ a vessel of mercury which as it rises at the
circumference, and falls in the middle may be made to make and break circuit with
a set of connections to the cells suitably arranged. Or I may use any ordinary
centrifugal governor similar to those used in steam engines, or a weight upon a

page_text: radial bar provided with a resisting spring or counterpoise to move a sliding
contact, which shall control the number of cells included in the circuit.
My improvements in measuring electric currents relate to two classes of measure-
ment. 1. That of currents actually passing by means of instruments called
galvanometers. 2. That of currents which have passed or of the quantity of work
done in a given time by instruments called voltameters. For the first of these
purposes, I construct coils of wire or sheet metal in pairs, one for each side of the
zero line as usual so as to form a chamber in which the moving parts of the
instrument may move freely. I arrange two such pairs back to back, so that they
shall have reverse magnetic fields as is well understood. I construct moving
systems to work in the chambers in such a manner that they shall have opposite
magnetic actions and being fixed upon one axis all the influences shall tend to
move this axis in one direction in the same manner as is now done with what are
called astatic needles. But I cause these systems to derive their magnetic power
from the current itself, and so that this power shall always be proportionate to the
current passing, and being equal and opposite in the two neighbouring systems
they shall be subject to but little action from external influences. I arrange wires
as coils into which I cause all or part of the current to pass as well as through the
principal coils, upon the well known principle of Weber's dynamometer. My im-
provement consists in principle of combining two such instruments into one, and so
obtaining a compound astatic magnetic system actuated only by equal and opposito
internal forces. I may insert soft iron in the moving coils just described, so as to
convert them into electro magnets; or I use soft iron needles in which magnetism
is induced by the action of the current in the coils. This magnetising influence is
very slight while the needles are parallel with the currents, as in the zero position,
and most powerful when they are at right angles with the currents. I therefore
mount on the same axis two similar needles inclined at from 20 to 45 degrees, on
one side of the first pair. This second pair is therefore more strongly magnetised
at first and commences the movement, while on reaching 90° of deflection, they
tend to resist the motion which is therefore more regular through its whole range.
These needles may also work within the coils in which case the two needles for
each chamber may be made from one piece of iron, or they may be placed outside
the coils one at each end of the axis which supports them all. This iron system
may be supported in any ordinary way, but where wire coils are used in the
moving system I support them if horizontal by bifilar or torsain suspension through
which the required current can be passed or by fibres, in which case mercury
connections may be used as is well understood. In a vertical or inclined arrange-
ment, I use a metallic plate at each end of the axis to support it and make
connection, in which case the axis is made in two parts electrically insulated from
each other, and the wires are connected to these two parts.
Or I employ a vertical coil of wire which may have a plug of iron at its base,
and be sheathed with iron. In this I suspend an iron bar to be magnetised by the
coil and drawn into it, as is well understood. I also arrange a similar system so as
to cause its iron bar to ascend. The two bars being connected by a cord passing over
a wheel causes this to move and give the required indication by means of a point.
A similar action may be obtained with this apparatus in other than a vertical
position, but not so conveniently. This improvement consists in using the two
systems so as to give opposite polarities to the bars, and so produce a system little
subject to external influences.
Or I may employ an electro magnet to attract a mass of soft iron, and place
between these mercury or other liquids contained in a compressible or elastic vessel
provided with a glass tube, into which the mercury will be forced, and I may partly
counterpoise the armature by means of a conical iron weight suspended in a vessel
containing mercury so proportioned that its increasing weight as it rises out
of the mercury shall resist the increasing power of the magnet as the armature
approaches.

page_text: I may graduate these various instruments upon the system described in my
Patent, No. 1558 of 1873, so as to cause them to indicate current in any required
definite unit.
In my improvements in instruments for measuring and recording currents which
have passed in a given time I avail myself of any suitable chemical decomposition.
Those decompositions in which gases are generated may be used to measure currents
by combining with the decomposition cells a meter such as is employed in measuring
gas, but as these introduce undesirable complications I use such decompositions as
do not produce the effect known as polarigation of the electrodes. I therefore
employ those actions which result in the deposition of a metal in a solution of the
same metal, such as copper in sulphate of copper.
-
-
I use two plates of the metal, and cause each to become alternately the anode
when the other plate has lost so much weight as represents the unit of current
employed under well understood laws, and I cause this change of direction in the
current to be effected by the weight of metal passed from one plate to the other.
This may be effected by various arrangements of apparatus. I therefore describe
the principles of my improvement by aid of Figures 12 and 13. The two plates of
metal are shewn by A and C, suspended by spiral springs, or in any equivalent
manner which will permit them to descend and rise according to their relative
weights. As arranged, A is the anode and C the cathode, and the point of change
of circuit is at hand. I is an armature of iron mounted upon a frame of insulating
material provided with plates of metal opposite the points a, c, from which connec-
tion is made. These points have a second similar pair behind them in Fig. 12,
connected across as shewn in Fig. 13, in which + and are the bars supporting
the armature, by which also connection is made from the + and terminals to
the respective pairs of points. These points and the arinature constitute therefore
a revering commutator, and other modes of effecting the purpose may be used.
As shewn, the armature, which is arranged to lie on the side on which it is placed,
closes the circuit through the points a * and c It enters by + to the armature,
passes to a + and to the anode A, across the solution to the cathode C, and through
c - to the
terminal. M is an electro magnet, one end of the wire of which is
connected to c, the other to the point d, with which a circuit can be closed when
the weight of C brings the point e into contact with it. As soon as this occurs M
becomes active, draws the armature over, and reverses the connections in the
decomposition vessel, and at the same time throws M out of the circuit. For this
purpose the resistance of the connection between c and cand that of M must
be so balanced as to enable sufficient current to pass into the magnet; or the wire
in M may be connected in other evident modes to increase the power of M. A
similar magnet, not shewn, is provided on the other side of the armature. The
motion of the armature is caused to move a ratchet wbcel one tooth, and by this
means to record in well understood manner the number of reversals of current, cach
of which represents a definite quantity of electricity passing. It is not essential
that this wheel system should be moved by the armature, as a separate magnet may
be employed, but that action is shewn as being the simplest exposition of the
principles involved.
-
I may use screens or divisions in the decomposition cells to regulate the direction
of the deposit upon the electrodes and control the resistance, and I may use plates
of curved, cylindrical, or other form; or I may use cylinders mounted on an axis, so
that they may rotate as the change of weight on the nearest parts causes_displace-
ment of the centre of gravity, the essential point of this portion of my Invention
being the production of motion in a set of wheels by the agency of plates of metals
alternately dissolved and deposited on. When the apparatus is employed to
measure large currents I provide it with shunts upon well understood laws, so as
to allow only a definite proportion of the current to pass into the decomposition
Having now particularly described and ascertained the nature of the said Inven-
cell.
4
5

page_text: tion, and in what manner the same is to be performed or carried out in practice, I
hereby declare that I claim,-
1. The combinations of induced and inducing systems in dynamo-electric machines,
substantially as described.
2. The use of iron cores as described, in which an electric current is set up and
utilized.
3. The use of pole pieces essentially as described for the purpose of uniting separate
.magnetic systems.
4. The use of pole pieces substantially as described for the purpose of constructing
annular systems of electro-magnets out of two or more segmental parts.
5. The connecting together of magnets or electro-magnets formed of several
plates, so as to constitute a series of consequent poles, forming a succession of alter-
nate poles externally in an inducing system, substantially as described.
6. The construction of the inducing system of the Pacinotte ore gramme type in
a circular form, enclosing the induced system, or as discs parallel with the induced
system.
7. Constructing discs of an inducing system of plates, with projections forming
cells, in which the wire is wound.
8. The construction of commutator with exchangeable contact parts, substantially
as described.
9. Employing with dynamo-electric machines secondary batteries in such manner
that the speed of the machine controls the number of cells acting in the battery.
10. The several forms of galvanometer, as described.
11. Measuring currents which have passed, or the quantity of electricity which
has traversed a circuit, by means of metallic deposition on alternate plates, so as to
cause the weight of metal deposited to actuate a recording apparatus.
In witness whereof, I, the said John Toby Sprague, have hereunto set my
hand and seal, this Twenty-second day of May, in the year of our Lord
One thousand eight hundred and seventy nine.
JOHN T. SPRAGUE. (L.S.)
Witness,
T. MORGAN,
Secretary,
Inventors' Patent-right Ass"., Limited,
21, Cockspur Street.