IMPROVEMENTS IN ELECTRIC METERS
Year: 1883

page_text: LETTERS PATENT to James Edward Henry Gordon of Kensington in the
County of Middlesex for an Invention of "IMPROVEMENTS IN ELECTRIC
METERS
"
PROVISIONAL SPECIFICATION left by the said James Edward Henry
Gordon at the Office of the Commissioners of Patents on the 12th June 1883.
JAMES EDWARD HENRY GORDON of Kensington in the County of Middlesex
"IMPROVEMENTS IN ELECTRIC METERS.'
"1
The invention relates to improved meters for registering the quantity of
electricity or of electric energy used for lighting or other purposes.
In inany
existing meters the portion of the apparatus moved by the electricity has to move
the registering apparatus. The necessary friction of the latter introduces errors.
In the apparatus which is the subject of the present invention the part actuated
by the electricity moves freely and a motion actuated by clockwork moves the
counter at short intervals through a distance depending on the position of the part
moved by the electricity.
In order that the nature of the Invention may be more clearly understood I
describe one way of carrying it out.
Either the whole or a known part of current to be recorded passes through the
coil of a galvanometer or other apparatus for measuring electric current or energy.
A convenient form of which is more particularly described below.
In this form the axis carrying the pointer of the galvanometer is horizontal.
Fixed on the axis and moving with it is a disc of thin brass or other light rigid
material. This disc is cut to an elliptical or other curved shape the curve being
determined by experiment so that the vertical radius has its maximum length
when there is no deflection of the galvanometer and gets less as the deflection
increases so that (neglecting small corrections) there is an equal decrease of radius
for the increase of deflection corresponding to each unit increase of current or of
energy.
A clock is fixed near the galvanometer and on its hour axis or other axis is a
notched wheel which allows an arm to drop at intervals of say ten minutes. This

page_text: arm in its zero position is held just clear of the upper edge of the disc when there
is no current.
When dropped it falls till it is stopped by the edge of the disc.
If there is no current it falls practically no distance but if a current is passing the
arm falls a greater or less distance according to the amount of deflection.
The edge of the disc is preferably notched or cut into saw teeth or otherwise
roughened so that the arm falling on the sloping edge shall not push the disc round
and alter the deflection.
Immediately after the fall the clock raises the arm to its zero position. As it
rises a catch on it engages a ratchet wheel and moves a counter consisting for
instance of a train of wheels like those of a gas meter.
The amount indicated depends on the distance which the arm had fallen i.e. on
the deflection. Or the arm might be made to turn the train of wheels in its
descent instead of its ascent but not so advantageously.
A convenient form of galvanometer for measuring current is the following:-
Instead of the ordinary magnetised needle a short tube of soft iron is used which
plays between two poles of an electro magnet through the wire of which the
current passes. Its position of rest is either equatorial or preferably at some angle
intermediate between the axial and equatorial lines. The magnet tends to set it
axial. It is brought back to zero by a weighted arm which hangs vertically when
there is no current or a spring may be used.
This form is particularly convenient for alternating currents. Any other
suitable form of galvanometer may however be used.
-
If it should be desired to record energy then instead of the soft iron bar a coil
of fine wire may be used connected through resistance coils with the + and
mains respectively.
The clock may be driven in any convenient way by weight, spring, or by an
electric or water or other motor or made self winding by these or any other
convenient means.
If preferred a magnet may be attached to the clock to stop it when no current
at all is passing. The horizontal form of galvanometer is not essential but appears
the most convenient.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said James Edward Henry Gordon in the Great Seal Patent Office
on the 12th December 1883.
JAMES EDWARD HENRY GORDON of Kensington in the County of Middlesex
"IMPROVEMENTS IN ELECTRIC METERS"
This Invention relates to improved meters for registering the quantity of electricity
or of electric energy used for lighting or other purposes. In many existing meters
the portion of the apparatus moved by the electricity has to move the registering
apparatus. The necessary friction of the latter introduces errors. In the apparatus
which is the subject of the present Invention the part actuated by the electricity
moves freely and a motion actuated by clockwork moves the counter at short
intervals through a distance depending on the position of the part moved by the
electricity.
In the drawings hereunto annexed I have shewn two examples of electric meters
constructed according to my Invention.
Figures 1 and 2 are elevations both partly in section of one form of my electric
meter.
In this form the galvanometer used is composed of a short tube or bar A of soft
iron mounted upon a horizontal axis B and free to play between two poles C of an
electro magnet through the coils D of which the current or some known part of
the current to be measured is passed.
On the axis B is also a weighted arm B* the weight of which keeps the bar A
in the position shewn at Figure 1 whenever no current is passing through the
galvanometer coils. Preferably also I fix on the axis a pointer F which at this
time will point to a zero mark of a fixed scale.
Upon the axis B is also secured a disc E of thin brass or other light rigid
material-this disc is cut to a curved shape determined by experiment. The disc
is fixed on to the axis in such a position relatively to the weighted arm E and
index pointer F that when this pointer points to zero and there is no deflection of
the galvanometer the vertical radius has its maximum length. The disc is also so
shaped that as the galvanometer is so deflected and a fresh radius is brought into
the vertical position the length of this radius gets less and less so that (neglecting
small corrections) there is an equal decrease of radius for the increase of deflection
corresponding to each unit increase of current or of energy. One form to which
the disc has had to be shaped is shewn at Figure 3.
Both halves of the disc are shaped alike so that one side may balance the other.
The edge of the disc is preferably notched or cut into saw teeth or otherwise
roughened so that the arm falling on the sloping edge shall not push the disc round
and alter the deflection.
A clock is fixed near the galvanometer and on the axis of the minute hand is
fixed a notched wheel G. One arm of a lever H rests upon the periphery of this
wheel the other arm rests above the top of one arm of a lever I-the weight of
the other and longer arm of the lever I keeps the short arm of the lever H bearing
against the periphery of the notched wheel G.
The extremity of the longer arm when so held up in its zero position is just
clear of the upper edge of the disc when no current is passing.

page_text: Whenever by the rotation of the axis of the minute hand of the clock a notch
in the wheel G is brought below the end of the short arm of the lever H the longer
arm of the lever I is free to descend.
When allowed to drop it falls till it is stopped by the edge of the disc. If there
is no current passing it falls practically no distance but if a current is passing the
arm falls a greater or less distance according to the amount of deflection of the
galvanometer.
Afterwards when by the further revolution of the axis of the minute hand the
end of the notch comes against the lever arm H this lever is turned back to its
former position so raising the longer arm of the lever I away from the disc E.
Fixed to the lever I is an arm carrying a pawl K which engages with the teeth of
a ratchet wheel L-the axis of this wheel is concentric with the axis of the
lever I.
When the longer arm of the lever is raised the ratchet wheel is turned by the
pawl and the distance it is so turned will depend upon the distance the longer arm
of the lever I, has previously been allowed to drop and consequently upon the
amount of deflection of the galvanometer.
"
Another pawl M prevents the ratchet wheel from turning in the opposite
direction.
The number of rotations made by the ratchet wheel are recorded by the wheels
of the counter N. The axis of the first wheel of the train of wheels may for this
purpose have a ratchet wheel fixed upon it to be driven by a pawl which receives
a to and fro motion from a crank pin carried by the ratchet wheel L or may be
driven from this ratchet wheel in other convenient ways.
In this way the position of the galvanometer will in the construction shewn in
the drawing be recorded at intervals of every ten minutes-but it might be con-
structed to record the position of the galvanometer at shorter or longer intervals as
may be desired.
If preferred the record might be made during the fall instead of
during the rise of the arm I. The form of galvanometer shewn in Figures 1 and 2 is
particularly convenient for alternating currents. Any other form of galvanometer
may however be used.
If it should be desired to record energy then instead of the soft iron tube or
bar a coil of fine wire may be used connected through resistance coils with the
+ and mains respectively.
-
The clock may be driven in any convenient way as by weight spring or by an
electric or water or other motor or made self winding by thèse or other convenient
means.
If preferred a magnet may be attached to the clock to stop it when no current
at all is passing.
Another form in which my electric meter may be constructed is shewn at
Figure 4.
In this construction a galvanometer in the form of a solenoid drawing an iron
core into it against a spring or it might be a weight is employed and the longer
arm of the lever I when allowed to drop descends on to a pin' projecting from the
moveable core which plays to and fro through this solenoid coil.
In Figure 4 the parts which are similar to those shewn in Figures 1 and 2 are
marked with the same letters of reference. The solenoid coil of insulated wire
through which the current to be measured is passed is marked X the iron
core and the spring by which the core is upheld is marked Z. The pin on to
which the lever arm I is from time to time allowed to drop is marked Y¹.
It is not essential that the solenoid coil should be in a vertical position it might
in some cases be inclined or set horizontally so long as the lever arm I has to drop
a greater and greater distance according as the core is drawn inward into the
solenoid coil.
Having thus described my Invention and the manner of performing the same I
would have it understood that what I claim is:
The construction of electric meters in such manner that the part moved by the

page_text: electricity moves freely and independently of the registering apparatus and also in
such manner that the registering apparatus moved by clockwork or other motor
searches at short intervals for the position of the indicator of the electrical
apparatus and records the sum of the lengths of all the journeys taken by it in
its searches.
In witness whereof I the said James Edward Henry Gordon have hereunto set
my band and seal this tenth day of December in the year of our Lord One
thousand eight hundred and eighty three.