IMPROVEMENTS 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
of Middlesex for an Invention of "IMPROVEMENTS IN ELECTRIC METERS
"
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 quantity of
electricity passing through a conductor at any time is indicated by an index pointer
passing over a graduated scale, which index pointer moves forward or backward
from or towards the zero point of the scale according to whether the quantity of
electricity passing through the conductor is greater or less. The index pointer may
also be made to register its movements on a travelling sheet of paper by means of
a pencil or style whereby not only the quantity passing at any given time but the
total quantity passed during any given time is indicated graphically.
According to one arrangement the index pointer is moved by the extension or
contraction of a metallic spiral caused by the change of temperature produced
therein by the passage of a greater or lesser quantity of electricity through the
same. The said spiral is composed of a metal which offers considerable resistance
to the passage of the current, such as Platinum or Iridio-platinum for example.
It may be combined with another more elastic metal or with a spring for the
purpose of returning the spiral and the index to the normal position with greater
certainty when the current ceases to pass.
In order to neutralize the effect of the varying conductivity of the spiral due to
changes of atmospheric temperature, the current may be passed through a liquid
or other resistance (the conductivity of which varies with a change of temperature
in a manner the reverse of that of the metal composing the spiral) before or after
passing through the said metallic spiral.

page_text: The spiral may be connected to the index finger by levers and rods or any other
suitable mechanism and the traversing paper for receiving the diagram may be
moved by any of the well known means applicable to that purpose, such as clock-
work or electrical apparatus.
According to another arrangement I employ one or more circular segment-shaped
solenoids arranged circumferentially, the core or cores of which are connected more
or less directly with the index-pointer which latter is moved to a greater or lesser
extent by the attraction of the core or cores into, or their repulsion from the
solenoid or solenoids. When the current of electricity is passed through the coils of
the latter the amount of movement being dependant upon the quantity of current
passing at any given moment. The return of the index to zero may be assisted by
a suitable spring, and the traversing paper may be operated as before by any
suitable means. A small catch may be operated by the index finger when the
latter returns to zero for the purpose of stopping the motion of the said paper until
the current passes again.
Instead of plain iron cores in the solenoids smaller solenoids or small electro
magnets may be employed receiving their current from a derivation of the main
conductor, and the apparatus may be so arranged that the attractive action of one
solenoid may be assisted by the repulsive action of another.
According to a modification of the last mentioned arrangement the solenoid or
solenoids or their cores may be made straight and connected with the index finger
by any suitable arrangement of mechanical or other devices...

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 quantity of
electricity in units or "Webers" passing through a conductor at any time is
indicated by an index pointer passing over a graduated scale, which index pointer
moves forward or backward, from or towards the zero point of the scale according
to whether the quantity of electricity passing through the conductor is greater or
less. The index pointer may also be made to register its movements on a travelling
sheet of paper by means of a pencil or style, whereby not only the quantity passing
at any given time, but the total quantity passed during any given time, is indicated
graphically.
According to one arrangement, the index pointer is moved by the extension or
contraction of a metallic spiral caused by the change of temperature produced.
therein by the passage of a greater or lesser quantity of electricity through the
same. The said spiral is composed of a metal which offers considerable resistance
to the passage of the current, such as Platinum or Iridio-platinum for example.
It may be combined with another more elastic metal or with a spring for the
purpose of returning the spiral and the index to the normal position with greater
certainty when the current ceases to pass.
Figure 1 of the drawings illustrates a meter constructed in accordance with this
arrangement; B is the casing containing the mechanism, a is a fixing secured to
the back of the casing B, c. d is the metallic spiral which is carried about the
middle of its length by the fixing a. The two ends of the metallic spiral c. d are
connected respectively to the two lever arms i, j, both of which are connected to
a third lever arm k, the whole being centred at the point l. E is an index arm or
pointer pivoted on the fixing b. This index arm E carries another arm m which
is connected to the arm k by the link n pin jointed to both. f is a pencil or stylus
carried in the outer end of the index pointer E; g is a strip of recording paper
carried over a drum behind the segmental opening through which the pencil or
stylus passes. This drum may be operated by suitable clock work, the winding
square of which is seen at p. 1, o and 2, q are the conductors conveying the
current to and from the spiral c. d. This spiral may be composed as above
described of two different metals, or of other suitable materials, for example the
part c may be made of Iridio-platinum to give the required electrical resistance,
and the part d of a steel spring to give elasticity to both; the two being electrically
insulated from each other. If preferred however, the spiral may be made of a
single material, and a special spring applied thereto to restore it to normal position
as above explained. The same effect may be produced by arranging the resistance
piece c. d. of forms other than the spiral, and I do not confine myself to the spiral
form.
It will now be understood that when a current is passed through the con-
ductor 2. q, o, 1, and through the resistance piece c. d, the latter will be heated in
proportion to the quantity of electricity passing, the spiral will be elongated, the
lever i, j. k will turn on its fulcrum, and will move the index E by the link n and
arm m, so as to cause the pencil or stylus f to traverse across the recording paper g

page_text: and to register the amount of deflection, which will be in proportion to the quantity
of current passing.
In order to neutralize the effect of the varying conductivity of the spiral due
to changes of atmospheric or ambient temperature, the current may be passed
through a liquid or other resistance h, (the conductivity of which varies with
changes of temperature in a manner the reverse of that of the metal or other
material composing, the spiral) before or after passing through the said spiral,
The liquid employed at h may be acidulated water for example, and the degree
of conductivity may be varied by bringing closer together or separating further
apart the two conducting points in the tube h by means of the top screw. This
arrangement thus acts upon the principle that metals, and liquids vary their
resistance oppositely when subjected to increase or diminution of temperature.
Instead of a liquid, carbon may be employed as illustrated in figure 2 as its
resistance varies with the temperature in a manner similar to liquids.
If the spiral and its attachments are not constructed very delicately, the liquid
or carbon resistance may be omitted, because the ambient temperature will not,
in that case, sensibly affect the indications of the instrument. But such resistance
dévices, if retained, may be made to perform an equally, if not still more
important function, namely the counteraction of the inconvenience arising from
the fact that neither Iridio-platinum nor any other metal offers a constant
resistance when subjected to a considerable degree of heat. The error that would
be occasioned by this variation of resistance can however be neutralized by
properly arranging resistances of opposite characteristics according to requirements.
The object of the reversing switch 7 shown in figure 1, and which is only used
periodically, is to enable the direction of the current through the liquid in h to be
reversed in order to redeposit any electrolysis that may have taken place..
The spiral may be connected to the index finger by levers and rods; as shown in
figure 1, or by any other suitable mechanism, and the traversing paper 9 for
receiving the diagram, may be moved by any of the well known means applicable
to that purpose, such as clock work or electrical apparatus.
According to another arrangement, I employ one or more circular segment
shaped solenoids or helices arranged circumferentially, the core or cores of which
áre connected more or less directly with the index pointer, which latter is moved
to a greater or lesser extent by the attraction of the core or cores into, or their
repulsion from the solenoid or solenoids when the current of electricity is passed
through the coils of the latter, the amount of movement being dependent upon the
quantity of current passing at any given moment. The return of the index to zero
may be assisted by a suitable spring, and the traversing paper may be operated as
before by any suitable means. A small catch may be operated by the index finger,
when the latter returns to zero, for the purpose of stopping the motion of the said
paper until the current passes again.
Figure 3 of the drawings illustrates a meter constructed in accordance with this
arrangement; B is the casing containing the mechanism; H, H are two solenoids
or helices fixed in the said casing. These solenoids or helices may be wound in the
peculiar manner well known and adopted by electricians to extend the saturation
point. CC are moveable cores adapted to pass into the solenoids or helices H, H.
They are each secured at one end to the arms E E of the index pointer E, which
is free to turn on the centre E2. A coiled spring d is fixed at one end to the
casing B, and at the other end to one of the Arius E!. The index pointer E carries
a pencil or stylus f which traverses across the recording paper'g in the same way
as in figure 1. 8 is a lever carried on the end of a rock shaft, the other end of
which extends into the case and carries a catch, which engages into some part of
the clockwork train, or other mechanism moving, the paper g, 'so as to stop the
same when the index pointer E on returning to the zero point moves the lever s to
the left in the figure...
:
8
It will now be understood that as the current passes through the conductor 1-2.
it passes also round the solenoids or helices H, H; and the iron cores C. C will be

page_text: drawn into the said solenoids or helices more and more in proportion to the quantity
of electricity passing through the conductor 1-2, and that the index pointer E will
be moved over the recording paper g in a like proportion indicating the quantity
of electricity passing. When the current is reduced, or ceases altogether, the
spring d draws the cores C, C, more or less out of the solenoids or helices, returning
the index E towards or to zero-When the recording paper g is moved by
electrical means the lever 8 may be caused to break the electrical connexion for the
purpose of stopping the movement of the said paper when the index pointer
returns to zero.
Instead of the plain iron cores C. C. shown in figure 3, smaller solenoids or small
electromagnets may be employed receiving their current from a derivation of the
main conductor; and the apparatus may be so arranged that the attractive action
of one solenoid or helix may be assisted by the repulsive action of another.
Figure 4 illustrates this arrangement. H. H are the fixed solenoids or
helices C. C. smaller solenoids or electro-magnets forming the cores adapted to pass
into the interior of the solenoids H. H. These cores are fixed to the arms E¹ E¹ of
the index pointer E as in figure 1. The index pointer E may be returned to zero by
a retractile spring as in figure 1, or by a weight W as shown in figure 4; the end of
its suspension cord V being secured to an eye adjustable on one of the arms E¹ so
that it can be placed nearer to, or further from the centre of motion, as may be
required. It will be seen that the smaller helices are formed of a derivation from
the main conductor. The four helices are of equal resistance and the current
circulates equally through them all-In the figure the cores are shewn in their
normal position, and they are kept so by the weight W until a current passes in
the conductor 1-2 when, in consequence of the peculiar winding of the helices, a
mutual suction action is produced on the left hand solenoid and core, and a mutual
repelling action on the right hand solenoid and core, whereby the index pointer E
is moved as in figure 3. The capacity may be regulated by moveable weights
added to the weight W.
It is obvious that a weight may be employed instead of a spring, to return the
index pointer to zero, in the arrangements shown in figures 1 and 3; and also that
any electrical device such as a Gramme ring or other device that will give a
vibratory movement to the index pointer carrying a pencil or stylus may be
substituted for the helices and cores or the compound double helices.
According to another modification the solenoid or solenoids, and their cores, may
be made straight, and connected with the index finger by any suitable arrangement
of mechanical or other devices.
Figure 5 of the drawings illustrates one form of this modification. B is the.
frame or casing of the instrument as before, H is the solenoid or helix, C is the iron
core, or it may be a smaller solenoid or helix, or an electro-magnet-The core C
may be arranged to act directly upon the index pointer E, or the motion may be
communicated thereto by means of pneumatic bellows G, as shewn, the weight W
returning the index pointer E to zero, and withdrawing the core C from the
solenoid H, when the electric current ceases to pass-The capacity of the meter
can also be varied by adding weights such as W₁ to the constant weight W.
Figure 6 illustrates a double helix arrangement similar to that shewn in figure 4
but with the outer and inner solenoids or helices straight instead of segments of
circles These twin helices may be placed in the same relation to the pneumatic
apparatus, and to the recording paper as the helix H and core C in figure 5. The four
cores are of equal resistance and the current circulates equally through them all→
In the two larger or female helices it traverses in the same direction, and in the
smaller or male helices in the opposite directions-As seen in the figure, the two
male helices are in their normal position, and are kept so by a weight similarly to
the arrangement shown in figure When the current passes in the line 1-2 a
suction or attracting action is produced on the right hand male helix, and a
repelling action on the left hand male helix-The two male helices are to be
connected to the index pointer in such manner that the attracting action of one

page_text: shall combine with the repelling action of the other to produce the desired motion
of the said index pointer.
A graduated scale may be applied for the end of the index pointer E to pass
over in either of the meters illustrated in figures 1, 3 or 5 whereby the quantity of
electricity passing at any given moment can be ascertained by simple inspection.
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 I do
claim as the improvements in electric meters intended to be secured by the within
in part recited Letters Patent is :—
First. The employment of a resistance piece so arranged and adapted that the
extension thereof caused by its rise of temperature, when the electric current
is passed through it, shall operate an index pointer or other indicating or
recording instrument to an extent proportionate to the current passing
through the conductor substantially as herein before described and illustrated
in figure 1 of the drawings.
Second. The combination in the same circuit with the resistance piece indicating
the current of a compensating resistance the conductivity of which varies
with changes of temperature in a manner the reverse of that of the material
composing the indicating resistance piece as herein before described and
illustrated in figures 1 and 2 of the drawings and for the purposes specified.
Third. The arrangements of solenoids and iron cores or of external and internal
solenoids through which the current to be measured, or a derivation thereof
passes and index pointers or other similar indicating or recording instruments,
the whole combined and operating substantially as hereinbefore described
and illustrated in figures 3. 4. 5 and 6 of the drawings.
Fourth. The combination of a travelling recording paper operated by clockwork or
otherwise with an index pointer or other indicating or recording instrument
whether the same be operated by the extension or contraction of a resistance
piece under the influence of change of temperature as shown in figure 1 or
by the attractive or repulsive action of one or more solenoids and cores as
shown in figures 3. 4. 5. and 6 of the Drawings substantially as herein before
described.
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.