MENTS IN ELECTRIC METERS
Year: 1882

page_text: LETTERS PATENT to Samuel Dimmick Mott of New York in the United
States of America, at present residing at Ebury Street, Pimlico, in the County
PROVISIONAL SPECIFICATION left by the said Samuel Dimmick Mott at
the Office of the Commissioners of Patents on the 29th September 1882.
SAMUEL DIMMICK MOTT of New York, in the United States of America, at
present residing at Ebury Street, Pimlico, in the County of Middlesex, " IMPROVE
MENTS IN ELECTRIC METERS."
This invention consists of certain arrangements whereby the speed of a train of
wheels constituting a counting or registering apparatus set in motion by a weight,
a spring, electric or other suitable means is caused to vary according to the quantity
of electricity passing through the conductor, so as to register the number of units
or "Webers" of electricity so passed.
According to one arrangement for effecting this object I employ an escapement,
a pendulum, and an escape wheel in connection with the train of counting or
registering wheelwork. The bob of this pendulum is caused to vary its position
on the pendulum rod according to the quantity of electricity passing, that is to say,
when a larger quantity of electricity is passing, the bob will be raised nearer to the
point of suspension of the pendulum so that the latter will oscillate quicker and
allow the train to revolve faster, and when a smaller quantity of electricity is
passing, the bob will be lowered into a position further removed from the point of
suspension and the pendulum will oscillate slower causing the train to run slower
also- In order to effect the rise or fall of the bob in proportion to the current
passing I employ various arrangements, for example a fixed Gramme ring with its
coiling is arranged so that the current to be measured or a derivation thereof is
passed through the wire forming the coiling of the said Gramme ring. The
armature of this Gramme ring is centred on an axis concentric with the said ring
and is held in a position of equilibrium when the apparatus is not in action by

page_text: :
means of a coiled or other spring. A cord or chain pulley is fixed on the axis of
the armature, and a cord or chain connected at one end of the bob of the pendulum
after passing over a guide roller is carried over the said pulley and fixed at its other
end to a balance weight. It will now be understood that when a current of
electricity is passed through the coils of the Gramme ring the armature will be
caused to turn on its axis to a greater or less extent according to the quantity of
electricity passing, the cord or chain will be drawn by the pulley, the pendulum bob
will be raised accordingly and the clockwork counting apparatus will register at a
speed proportionate to the current. When the current is weakened the armature
will be turned back by its spring, the bob will be lowered, and the registration will
take place slower in proportion to the reduced current. When the current ceases
altogether the spring returns the armature to its normal position. As the speed of
the registering train is required to be in direct proportion to the quantity of
current passing at any given time, and the lengths of the pendulum to give that
proportion must vary as the squares of the times of vibration, the bob should be
raised in such a proportion to the movement of the armature as will maintain a
constant proportion between the movement of the registering mechanism and the
amount of current passing. To effect this the cord or chain pulley on the axis of
the armature may be shaped as a snail, a spiral, or a fusee.
When a balance escapement is used instead of a pendulum the speed of oscillation
of the balance may be varied by the movement of the Armature, causing by
means of suitable appliances the stiffening or relaxing, or the shortening or
lengthening of the balance spring, whereby the balance is caused to oscillate quicker
or slower according to the position of the Armature, and consequently according to
the quantity of electricity passing. This action on the balance spring is similar to
that employed for the regulation of watches.
According to another arrangement instead of the train being regulated by the
varying length of a pendulum or the varying length or stiffness of a balance spring,
its speed may be varied in proportion to the current passing by means of a solenoid
through which the current to be measured is passed. The iron core of this solenoid
is connected by gearing racks and pinions, or levers with resistance flyers revolving
either in air or a liquid, and so connected with the train as to govern the motion
thereof according as the said flyers stand parallel to their axis of rotation, more or
less obliquely inclined thereto, or at right angles thereto-The core when drawn
more or less into the solenoid on the passage of the current through the latter
causes the said resistance flyers to turn more or less obliquely to their axis of
rotation whereby they suffer less resistance from the air or liquid in which they
revolve and are consequently free to revolve proportionately faster. Thus it will
be seen that the greater the quantity of electricity passed through the solenoid, the
further the core will be drawn into it, the more obliquely the resistance flyers will be
placed in reference to their axis, the less resistance they will meet with, the faster
they will revolve, and consequently the faster the registering mechanism will move.
When the current ceases altogether the core is withdrawn to its greatest extent
from the solenoid by a spring, and a finger or other instrument stops the registering
mechanism until the current passes again.
When the resistance flyers revolve in a liquid instead of being turned to a
greater or less obliquity with reference to their axis in order to reduce the
resistance they may be raised by the core of the solenoid more or less out of the
liquid to effect the same object.
.
According to another arrangement I employ a "Foucault disc" placed between
the poles of an electro magnet aud geared to the registering train. As the quantity
of electricity passed through the coils of the electro magnet increases, the "Foucault
disc" offers more and more resistance to revolution and the registering train is
'driven proportionately slower As in this case the indications of the registering
apparatus are inversely proportionate to the quantity of electricity passed, the
reading of the instrument has to be effected by making a calculation of the
following kind, that is to say by calculating a rule of three sum in which the dial

page_text: reading bears the same proportion to unity that the greatest possible reading of
the instrument bears to the amount or quantity of electricity that has passed.
Instead of connecting the "Foucault disc" directly with the registering train
whereby the above mentioned inconvenience is met with there may be introduced
between the "Foucault disc" and the registering train an arrangement of
mechanism such as a centrifugal governor and resistance flyers or other suitable
apparatus so adapted that as the "Foucault disc" increase in resistance and
reduces its speed, the said centrifugal governor shall collapse more or less and in
doing so shall operate the resistance flyers so that they shall offer less resistance to
the motion of the registering train and the speed of the latter shall thereby
increase in direct proportion to the increase in resistance of the "Foucault disc
whereby the indications may be read off direct from the dial by inspection only;
without the necessity of any calculation whatever.
"

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Samuel Dimmick Mott in the Great Seal Patent Office on the
29th March 1883.
SAMUEL DIMMICK MOTT, of New York, in the United States of America, at
present residing at Ebury Street, Pimlico, in the County of Middlesex " IMPROVE-
MENTS IN ELECTRIC METERS."
This Invention consists of certain arrangements whereby the speed of a train of
wheels, constituting a counting or registering apparatus, set in Motion by a weight,
a spring, electric, or other suitable means, is caused to vary according to the quantity
of electricity passing through the conductor, so as to register the number of units
Webers" of electricity so passed.
or "
According to one arrangement for effecting this object I employ an escapement,
a pendulum, and escape wheel in connection with the train of counting or
registering wheelwork. The bob of this pendulum is caused to vary its position
on the pendulum rod according to the quantity of electricity passing, that is to say,
when a larger quantity of electricity is passing the bob will be raised nearer to the
point of suspension of the pendulum, so that the latter will oscillate quicker, and
allow the train of wheelwork to revolve faster, and when a smaller quantity of
electricity is passing the bob will be lowered into a position further removed from
the point of suspension, and the pendulum will oscillate slower, causing the train
of wheels of the counting apparatus to run slower also. In order to effect the rise
or fall of the bob in proportion to the current passing, I employ various arrange-
ments, for example, a "Gramme" ring with its coiling is arranged so that the
current to be measured, or a derivation or portion thereof, is passed through the
wire forming the coiling of the said Gramme ring. The armature of this Gramme
ring is centered on an axis concentric with the said ring, and is held in a position of
equilibrium when the apparatus is not in action, by means of a coiled or other
spring, or by a weight.. A cord or chain pulley is fixed on the axis of the
armature, and a cord or chain connected at one end to the bob of the pendulum,
after passing over a guide roller, is carried over the said pulley and fixed at its
other end to a balance weight.
Figure 1. illustrates this arrangement: A. is a box or case containing the counting
apparatus which is set in motion by a weight, a spring, electric or other suitable
means. B is the escape wheel, which may be connected to the train of wheels
comprising the counting apparatus by any suitable mechanism; C is an escapement
adapted to the escape wheel B, and carried by the pendulum rods D, D, the centre
of oscillation of which is at E. F is the bob of this pendulum free to slide up
and down on the rods D. D. G is the Gramme ring fixed as shewn, and the coils
of which form part of the main conductor, or a derivation thereof. H. is the axis
upon which is centered and fixed the armature of the Gramme ring G. I is the
cord or chain pulley also fixed on the axis H. J is a cord fixed at one end to the
pendulum bob F, the other end after passing over the guide roller K is fixed to the
pulley I. L is another cord or an extension of J also fixed at one end to the
pulley I, and at the other end to the weight M, the office of which is to balance
the weight of the bob F. It will be obvious that any suitable form of Electro-
magnet other than the Gramme ring may be employed, and that the armature
must be arranged according to the kind of Electro-magnet employed. N is a
coiled spring one end of which is fixed to the axis H, and the other end to a fixed
point as at P.
It will now be understood that when a current of electricity is passed through

page_text: the coils of the Gramme ring or other electro-magnet G, its armature will be caused
to turn on its axis H, to a greater or less, extent, according to the quantity of
electricity passing, the cord or chain J will be drawn by the pulley. I, the pendulum
bob F will be raised accordingly, and the pendulum being set in motion the
clock work counting apparatus will register at a speed proportionate to the current.
When the current is weakened the armature will be turned back by its spring N,
the bob F will be lowered, and the registration will take place slower in proportion
to the reduced current. When the current ceases altogether the spring returns the
armature to its normal position, and the bob falls to the bottom of the pendulum
rods D. D. Qshows a catch by which the pendulum is held until the current
begins to pass. The said Catch may be released by suitable apparatus actuated by
the passage of the current, so that the starting of the meter shall commence
simultaneously with the said passage of the current.
As the speed of the registering train is required to be in direct proportion to
the quantity of current passing at any given time, and the lengths of the pendulum
to give that proportion must vary as the squares of the times of vibration, the bob
should be raised or lowered in such a proportion to the movement of the
armature as will maintain a constant proportion between the movement of the
registering mechanism and the amount of current passing. To effect this, the cord
or chain pulley on the axis of the armature may be shaped as a snail, a spiral or a
fusee.
Figure 2. illustrates this arrangement. Similar letters relate to like parts in both
figures 1 and 2. It will be seen that the cord or chain pulley I is formed as a
double fusee in order to realize the above requirement, that is to say, the form of
the spiral composing the fusee is such that, supposing that the passage of a certain
current through the meter causes the cord or chain J to lift the pendulum bob F,
in figure 1, one inch, double the current will cause the cord or chain J to lift the
bob F four inches, and so on, the rise of the bob being always in proportion to the
square of the current passing.
Figures 3 and 4 illustrate an arrangement in which the Gramme ring or other
Electro-magnet, with its armature, and cord or chain pulley are made to form the
bob of the pendulum. Those parts of these figures which correspond with similar
parts in figures 1 and 2 are indicated by similar letters of reference. In this case
the spring N, shown in figure 1, is not required, as the Gramme ring, and the
parts connected therewith, descend by gravity when the current is reduced or
ceases. The Gramme ring G, with its armature, and the cord or chain fusee
pulley I, are guided on the rods D D by the friction rollers r. r. These latter are
insulated from the Gramme ring G, as shewn at figure 4, and one or more of them
serves or serve to convey the current from the rods D D to and from the coils of
the Gramme ring. The current is conveyed to and from the coils of the Gramme
ring by the rods D. D. through the rolling contacts c c and curved springs d. d¹.
It will now be understood that, when a current traverses the coils of the Gramme
ring G, the armature is turned, and with it the cord or chain fusee wheel I, 'to
which the lower end of the cord J is fixed, in the direction of the arrow, whereby
'the said cord is wound on to the spiral groove of the wheel I, the increasing
diameter of which groove causes the said Gramme ring, and its attendant parts, to
be raised on the rods D D by an amount which varies as the square of the
_current passing. The speed of oscillation of the pendulum, is thereby made to
vary in direct proportion to the current, and consequently the counting apparatus
at A will also be moved in the like proportion When the current is reduced the
armature turns back more or less, and the cord J unwinds, allowing the Gramme
ring G, and its attendant parts, to descend more or less, and when the current
ceases altogether to descend to its lowest point, when it is caught by the catch Q
as already described in reference to figure 1.
When a balance escapement is used instead of a pendulum, the speed of oscillation
of the balance may be varied by the movement of the armature, causing, by means
of suitable appliances, the stiffening or relaxing, or the shortening or lengthening
1. W;

page_text: D
of the balance spring, whereby the balance is caused to oscillate quicker or slower
according to the position of the armature, and consequently according to the
quantity of electricity passing. This action on the balance spring is similar to that
employed for the regulation of watches.
Figures 5 and 6 illustrate this arrangement, Figure 5 being an under side view
of Figure 6 on the line x x of the latter. G is the Gramme ring or other suitable
electro-magnet, H the axis of its armature, and N the spring as already described
in reference to figure'l, I is a toothed wheel fixed on the axis H and gearing into
a pinion I on the axis of which is fixed a pulley 12 connected by a cord or belt J'
to a pulley I³, free to rotate on a stud S fixed to the support or case T. V is the.
balance wheel of the escapement (the escapement itself is not shown in the figures).
U is what is commonly called the hair spring of the balance attached at one end
to the fixed point U₁ and at the other end to the axis y of the balance wheel V.
W is a slotted bar sliding in guides across the pulley 1³, it has a rack formed on
one of its inner edges; which rack engages with teeth X X on the stud S. To this
sliding bar W is fixed the encompassing pin Y. It will now be understood that,
when a current passes the coils of the Gramme ring G, the armature and the
wheel I are moved round in the direction of the arrow, this turns the pinion I'
and pulley I which latter, by the cord or belt J¹, turns the pulley 1³, and with it,
the slide W round the stud S; thus causing the encompassing pin Y to be moved
on the spiral hair spring so as to shorten the virtual length thereof, causing the
balance wheel V to vibrate quicker. As the slide W turns round the stud S the
teeth on the latter move the slide endwise, so as to cause the encompassing pin Y
to follow the spiral form of the hair spring U. As the current increases the
pulley I³, and slide W, with its pin Y are moved further and further round so as
to virtually shorten the hair spring U more and more, and when the current is
reduced or ceases altogether, the spring N. restores all the parts to their normal
positions. The escapement is connected to counting mechanism, of any suitable
kind, in a manner similar to that already described in connection with figure 1.
According to another arrangement instead of the train being regulated by the
varying length of a pendulum, or the varying length or stiffness of a balance
spring, its speed may be varied in proportion to the current passing, by means of a
solenoid through which the current to be measured is passed. The iron core of
this solenoid is connected by gearing, racks and pinions, or levers, with resistance
flyers revolving either in air or a liquid, and so connected with the counting or
registering train as to govern the motion thereof, according as the said flyers stand
parallel to their axis of rotation, more or less obliquely inclined thereto, or at right
angles thereto. The core when drawn more or less into the solenoid on the passage
of the current through the latter, causes the said resistance flyers to turn more or
less obliquely to their axis of rotation, whereby they suffer less resistance from the.
air or liquid in which they revolve, and are consequently free to revolve
proportionally faster. Thus it will be seen that the greater the quantity of
electricity passed through the solenoid, the further the core will be drawn into it,
the more obliquely the resistance flyers will be placed in reference to their axis,
the less resistance they will meet with, the faster they will revolve, and
consequently the faster the registering mechanism will move. When the current
ceases altogether the core is withdrawn to its greatest extent from the solenoid by
'a spring, and a finger or other instrument stops the registering mechanism until the
'current passes again.
Figures 7 and 8 illustrate a meter constructed in accordance with this arrange.
ment. Figure 7 shows the meter with the case, the solenoid, and part of the shaft
in section, and figure 8 a partial section on line x²x² of figure 7, shewing the fan,
and the rear view of the case containing the clockwork.
The clock work or other driving power for the counting apparatus is contained
in the case A. It operates by the pinion a and wheel b to rotate tlie shaft 8. On
this shaft is a cross-head which carries the shaft s¹ of the fans B. The current
passes by the wires 1-2, and binding posts x-to the solenoid or helix H, in which
-

page_text: it acts upon the solenoid core C imparting thereto a sliding end motion upon the
shaft 8 in proportion to the strength of the current.
The bows f furnished with rack-teeth are moved endwise with the core C, they
act upon the pinions e, and turn them, and the fans B, to a greater or lesser
inclination. The greater the current the greater the inclination of the fans, and
the less their resistance in the air or other fluid within the surrounding case:-and
the less the current the greater the inclination and resistance of the fans. The
contractile spring d acts in the opposite direction to the solenoid magnet, and the
clockwork can run faster and make a higher register upon the Dials D when there
is a strong current than when there is a weak one, because the resistance of the fan
is in the inverse proportion to the strength of current. Hence the registration
will be in proportion to the current, and when there is no current the stop
comes into contact with the block C on the case A, and prevents the clock-work from
moving.
The train of gearing between the shaft of the pinion a and the hands on the
dials D may be of any desired character. The divisions on the dials are adapted to
indicate the electric energy passing over the circuit.
.
The manner of indicating the electric energy consumed may vary, but should be
based upon established data, so as to denote units etcetera.
In consequence of the racks f being at the same sides of the respective pinions e,
the fans are turned together by the shaft 8 and, although the fans stand in the
same plane, there will not be any unnecessary friction of the shaft & in its bearings,
because there is no tendency to move the shaft end wise, as one fan in revolving has
the direction of a right-handed screw-propeller, and the other that of a left-handed
screw-propeller.
To prevent the different angles which the fans B assume from interfering
detrimentally with the magnetic action of the solenoid upon which depends the
accuracy of the record, two pairs of fans may be employed; the axes of such fans
being placed at right angles to each other and when rotated by the solenoid they
move in opposite directions on their own axes.
The case in which the fans B revolve is made for preventing injury to the parts
of the meter, and for excluding external currents of air. If desired such case 'may
be made tight, and contain a fluid or liquid such as oil, glycerine, alcohol, or
petroleum.
:
When the resistance flyers revolve in a liquid instead of being turned to a
greater or less obliquity with reference to their axis in order to reduce the résistance,
they may be raised by the core of the solenoid more or less out of the liquid to
effect the same object.
Figure 9 illustrates this modification.
7.
In this case the shaft stands vertically with the fans B below it, the said fans
are raised out of the liquid by the core C of the solenoid H, and the resistance is
thereby lessened in proportion to the increase of the current. The spring d serves
to partially support the weight of the core and fans, and when there is no 'current
through the solenoid the fans B are prevented from revolving by coming against
the projections c at the bottom of the case M.
"
The rod C, forming the core of the solenoid, is suitably guided so that it may be
rotated with the fan by the tooth wheels e¹, f', the latter having a feather passing
into a groove in the core-rod C.
"
The wheels a b, the gearing and spring in the box A, the dials and hands D, and
the winding square p may be similar in both forms of apparatus.
The cores C may be made in sections of soft iron with thin washers of neutral
material between them, so as to extend as much as possible the saturation' point of
the magnetic action in the solenoids H.
The fans may be made of modified or irregular shape (as illustrated by dotted
lines in figure 9) in order that the meter may be calibrated 'to a true and
... I + 1 * +91
exact record,
5.

page_text: According to another arrangement I employ a "Foucault disc" placed between
the poles of an electro magnet, and geared to the registering train. As the quantity
of electricity passes through the coils of the electro-magnet increases the "Foucault
disc" offers more and more resistance to revolution, and the registering train is
driven proportionately slower.. As, in this case, the indications of the registering
apparatus are inversely proportionate to the quantity of electricity passed, the
reading of the instrument has to be effected by making a calculation of the
following kind; that is to say, by calculating a rule of three sum, in which the
dial reading bears the same proportion to unity, that the greatest possible reading
of the instrument bears to the amount or quantity of electricity that has passed.
Figure 10, illustrates this arrangement. A is a case containing the clockwork
registering apparatus, the winding square of which is represented at P¹. D. is a
dial face with index hands for indicating in the usual way. E, E, represent the two
branches of an electro-magnet, the pole pieces of which are shown at P P. N. is
the "Foucault disc" adapted to turn between the poles of the electro-magnet, being
carried on the shaft M (the bearings of which are not shown). This shaft M is
connected by gearing as shown to the registering train in the case A. The flyer F
is connected by gearing with the "Foucault disc" and acts as a constant resistance.
When the apparatus is at rest one or other of the projections c, c on the flyer F
rests upon the pin t'of an oscillating armature a. When a current passes through
the line 1-2 the electro-magnet E E is magnetised the armature a is attracted, the
pint is withdrawn from under the projection c, and the flyer, and the disc N are
set in motion by the clockwork in the case A through the gearing shewn. When
the current ceases the armature a is liberated, the pint resumes its normal position,
one of the pins c on the flyer comes against it, and the apparatus is stopped. The
greater the quantity of electricity passing through the line 1-2 the greater is the
resistance to the revolution of the disc N, and the less will be the indication on the
registering dial D. The registering dial or dials may be more conveniently
arranged as shown in figure 11. The capacity of the meter as shown by the dials
is 100,000 revolutions which are standardized to record the flow of 1 unit of
current. As the units are increased by the addition of lamps, or by increase of
candle power, the index hands of the meter diminish in speed in an uniform
proportion, so that if 100 units give 100,000 revolutions, 200 units should give
50,000 revolutions. Or, reversing the proportion, if 100,000 revolutions indicate a
flow of 100 units, then 50,000 revolutions should indicate a flow of 200 units, and
so on. For example if the index shows 58,250 then 58,250: 1 :: 100,000: 1.71 units
or "Webers."
When the counting or registering train of wheelwork is moved by electrical
means, such as an electric motor for example, I connect such motor direct to a
simple train of wheels such as that employed in the counters of gas meters, which
from its construction requires exceedingly little power to move it, and its resistance
to revolution is practically constant at all speeds. The speed with which an
electric motor will run is directly proportional to the amount of current energizing
it, consequently such a train of wheel work is well adapted to register the speed.
of such a motor. Figures 12 and 13 illustrate an arrangement of this kind. A is
an electric motor of any suitable type, contained in the casing B. Its revolving
axis C is connected directly by means of a cord, worm or tooth gearing, to a
registering train, such as that employed in gas meters, and contained in the case D,
which is furnished with indicating dials of the ordinary gas meter type as shown
in figure 13. R in figure 12 is a resistance spool to be used when the motor is run
in a shunted circuit. At S and S¹, figure 13, are shown sealings on the terminal
screws to prevent the meter from being tampered with.
Having now described the nature of the said Invention and the manner in
which the same is to, or may be carried into effect, I would have it understood
that I do not confine myself to the precise details described and illustrated as they
may be varied without departing from the nature of the said Invention; but what

page_text: claim as the improvements in electric meters intended to be secured by the
in in part recited Letters Patent is :-
The combination of a Gramme Ring or other suitable electro-magnet excited
by the current to be measured or a derivation thereof, and its armature
adapted to rotate under the action of the said Gramme ring or other
suitable electro-magnet, with a pendulum or balance wheel adapted to
regulate or govern, by means of an escapement, the motion of a counting
apparatus of any suitable construction, the rotation of the aforesaid armature
being caused to raise or lower the bob of the said pendulum, or to shorten
or lengthen the hair spring of the said balance wheel, so as to cause the
said pendulum or balance wheel to move at a rate proportionate to the
current of electricity passing substantially as hereinbefore described, and
illustrated in figures 1, 2 and 3 of the Drawings:
nd In combination with a Gramme ring or other suitable electro magnet
excited by the current to be measured, or a derivation thereof, its armature,
and a pendulum regulating or governing the speed of motion of a counting
apparatus, the cord or chain pulley constructed with a snail, spiral or fusee
for the purpose of raising or lowering the bob of the pendulum through
distances such that the pendulum shall oscillate at speeds directly propor-
tionate to the current passing, substantially as herein before described, and
illustrated in figure 2 of the Drawings.
乖
d In combination with a Gramme ring or other suitable electro magnet
excited by the current to be measured or a derivation thereof, its armature,
and a balance wheel regulating or governing the speed of motion of a
counting apparatus, the mechanism for moving the encompassing pin along
the hair spring for the purpose of decreasing or increasing the length of
such hair spring and for moving the encompassing pin to or from the centre
so that it shall follow the spiral form of the spring, whereby the balance
wheel is caused to vibrate at speeds proportionate to the current passing
substantially as hereinbefore described, and illustrated in figures 5 and 6 of
the drawings.
rth The combination with a train of gearing and registering devices moved by
a weight, a spring, electric, or other suitable means, of a solenoid or helix
through which the current to be measured passes, a movable iron core
acted upon the said solenoid or helix, and fans resisting the revolution
of the mechanism, such fans being controlled by the action of the aforesaid
solenoid or helix on its iron core, in such manner that the greater the
current the less the resistance to the revolution of the mechanism, the whole
arranged, adapted and operating substantially as herein before described, and
illustrated in figures 7. 8 and 9 of the drawings.
h The combination with a train of gearing and registering devices moved by
a weight, a spring, electric, or other suitable means, of a "Foucault disc
rotating between the poles of an electro-magnet through the coils of which
the current to be measured, or a derivation thereof passes, such "Foucault
disc" being so connected with the registering devices that the speed of the
latter is caused to vary in proportion to the speed of the said "Foucault
disc which speed varies in inverse proportion to the current passing
through the coils of tlie electro-magnet, substantially as hereinbefore
described and illustrated in figures 10 and 11 of the drawings.
In combination with the mechanism comprising the fifth claim Clause the
arrangements for stopping and starting the apparatus automatically when
the current is passed or stopped, as herein before described, and illustrated in
figure 10 of the Drawings.
nth The combination of a train of gearing constituting a counting device
similar to that employed in gas meters, with an electric motor which
receives its motion from the current to be measured, or a derivation thereof,

page_text: 3.
whereby direct indications are obtained without the intervention of variable
resistance devices substantially as hereinbefore described, and illustrated in
figures 12 and 13 of the Drawings.
.
. 42
In witness whereof I the said Samuel Dimmick Mott have hereunto set
my hand and seal this first day of March in the year of our Lord One
thousand eight hundred and eighty three.