IMPROVEMENTS IN ELECTRIC-CURRENT METERS
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by the said St. George Lane Fox at the
Office of the Commissioners of Patents on the 24th December 1881.
ST. GEORGE LANE Fox of Queen Anne's Gate in the City of Westminster,
"IMPROVEMENTS IN ELECTRIC-CURRENT METERS"
This Invention has reference to improvements in electric-current meters, and
especially to that class of apparatus described in the Specification of former Letters
Patent granted to me and dated 14th Nov. 1878 No. 4626 in which apparatus
the position or motion of an armature due to the amount of current passing through
a corresponding electro magnet, controls the working of the clock work or mechanism
of a counting apparatus.
One part of this Invention consists in the employment of a magneto-electric
motor to give a constant motion to a certain shaft in the meter-I use a horizontal
shaft free to oscillate about a vertical axis passing through its centre; at the ends
of this shaft I place two armatures, each opposite an electro magnet; or there may
be only one armature and a corresponding electro-magnet. I arrange that these
magnets (when there are two) are put into action alternately by springs which
make contact according to the position of the shaft, and by properly balancing and
weighting the shaft I obtain perfectly regular oscillations. I employ an auxiliary
spring in connection with the shaft so as to ensure one of the connections being
made when the instrument is at rest so that it may start directly any current
flows.
The speed can be controlled by limiting the time during which the current passes
across the contact pieces and this may be effected by means of screws to act on the
springs.
I make all the contacts by preference of an alloy of platinum and iridium in the
proportion of about 30 parts of iridium to 70 of platinum.
To the shaft above mentioned I attach a paul which oscillates with it and this

page_text: paul engages in the teeth of a horizontal wheel so as to move it through a definite
angle for every oscillation of the shaft; an arrangement-a kind of escapement―
may also be added to ensure the wheel only moving through a certain angle, so as
to check the momentum of the wheel when struck by the paul.
Another part of this Invention consists in a method of transferring the constant
motion of the wheel above mentioned to another shaft so as to make the angular
velocity of this shaft vary with the position of the above mentioned armature.
The wheel above mentioned is keyed on a vertical shaft, which carries at its
extremity a universal joint to the other end of which is fastened another shaft and
this shaft carries a piece shaped like a cone, vertex upward, keyed centrally on the
top shaft; thus while I can give the wheel a constant angular velocity in its own
plane and thus rotate the shaft carrying the cone, I can at the same time place the
cone shaft at any angle with the wheel shaft-I further make the cone engage in
frictional contact with a small wheel or disc keyed on a vertical shaft, so that when
the cone rotates this wheel or disc also rotates in its bearings, and with more or
less angular velocity according to its position on the cone, this position I make to
vary with the relative position of the magnet and armature, so that when more
current is flowing through the magnet, the armature-to which a lever is attached-
draws down the shaft carrying the friction wheel or disc and consequently engages
it with a larger diameter of the cone, giving the wheel an increased angular
velocity. I make the shaft which carries the friction wheel actuate a counting
apparatus whose motion thus varies with the current passing through the electro-
magnet.
To obtain a convenient parallel motion at the connection between the armature
lever and the shaft carrying the friction wheel, I adopt the following arrange-
ment -I key on the shaft a small collar, on each side of it I slip a larger collar on
the shaft and these two larger collars have slots in them larger than the diameter
of the shaft. I support these two collars on each side in a small cradle which
swings easily in a fork on the armature lever, so that when the lever rises the two
large collars can remain parallel to the fixed collar and at the same time they can
be drawn back, and as the two larger collars bear easily upon the smaller, every
motion of the lever is thus communicated to the shaft while it rotates.
Another part of this Invention consists in making the contour of the friction
cone follow such a course that the friction wheel shall be at the right diameter of
the conc for a given amount of current. I also cover the cone or the wheel-or
both with india rubber or other suitable material in order to ensure absence of
slipping between the two.
Another part of the Invention consists in compensating for the variable attrac-
tion of the magnet on the armature as the distance between them varies. I adopt
a bell crank arrangement with a weight so that as the armature gets pulled down
the leverage on the weight increases; or I may use a disc with a strap or chain
passed round its circumference and a weight attached; I key this disc excentrically
on a horizontal axis so that as it gets turned round by the action of the armature
the leverage on the weight increases, or I can make the latter constant and nake
the leverage of the armature vary by this means.
Although I have herein before described that the working of the meter is con-
trolled by the position or motion of an armature due to the amount of current
passing through a corresponding electro magnet, it is evident that any other
apparatus which is similarly affected by the amount of current passing through it
may be employed, such for example as a solenoid or a galvanometer.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said St. George Lane Fox in the Great Seal Patent Office on the
24th June 1882.
ST. GEORGE LANE Fox of Queen Anne's Gate in the City of Westminster
"IMPROVEMENTS IN ELECTRIC-CURRENT METERS
This Invention has reference to improvements in electric-current meters, and
especially to that class of apparatus described in the Specification of former Letters
Patent granted to me and dated 14th November 1878 No. 4626 in which apparatus
the position or motion of an armature due to the amount of current passing
through a corresponding electro magnet controls the working of the clockwork or
mechanism of a counting apparatus.
According to my present Invention which is illustrated in the annexed Drawings,
Figure 1 being a plan and Figure 2 a side elevation, I employ a magneto-electric
motor to give a constant motion to a certain shaft in the meter. CC represent the
electro magnets of such a magneto electric motor-I use a shaft G free to oscillate
about an axis E passing through its centre; at the ends of this shaft I place
2 armatures D D each opposite one of the electro magnets C C (or there may be
only one armature and a corresponding electro magnet); I arrange that these
magnets (when there are two) are put into action alternately by springs F F
which make contact according to the position of the shaft G in the same way as
the ordinary "make and break" of an electric bell or Ruhmkorff coil and by
properly balancing and weighting the shaft I obtain perfectly regular oscillations.
I employ an auxiliary spring I in connection with the shaft G so as to ensure that
one of the connections is made when the instrument is at rest so that it may start
directly any current flows.
The speed can be controlled by limiting the time during which the current
passes across the contact pieces and this may be effected by means of screws H H
acting on the springs F F.
I make all the contacts by preference of an alloy of platinum and iridium in
the proportion of about 30 parts of iridium to 70 parts of platinum.
To the shaft G I attach a paul K which oscillates with it and this paul engages
in the teeth of a wheel L so as to move it through a definite angle for every
oscillation of the shaft G; an arrangement,-
,-a kind of escapement-may also be
added to ensure the wheel L only moving through a certain angle, so as to check
the momentum of the wheel when struck by the paul.
I transfer the constant motion of the wheel L to another shaft connected with
the meter so as to make the angular velocity of this shaft vary with the position of
the armature B, the position or motion of which is due to the amount of current
passing through the electro magnet A whose coil forms part of the circuit or a
shunted portion of the circuit of the conductor the electric current passing through
which it is wished to measure.
The manner in which I prefer to transfer the constant motion of the wheel L to
a shaft connected with the meter as above mentioned is as follows:-
:
The wheel L is keyed on a shaft N which carries at its extremity a universal
joint connecting it with another shaft P to which is keyed centrally apex
upwards a cone shaped piece Q which is thus free to rotate when at any angle with
the shaft N-The cone Q engages in frictional contact with a wheel or disc R
keyed on a shaft M and as the cone rotates at a uniform angular velocity the
shaft M is caused to rotate at a greater or less speed according as the wheel or
disc R engages with a larger or smaller diameter of the cone. As the position of

page_text: the shaft BI carrying the disc R depends upon the position of the armature B to
which it is connected by the lever T (which is balanced by the spring V) I thus
make the angular velocity of rotation of the shaft M a measure of the attraction
between the electro magnet A and the armature B-I make the shaft M actuate a
counting apparatus X whose motion thus varies with the current passing through
the electro magnet A.
The contour of the friction cone should follow such a curve that the friction
wheel shall be at the right diameter of the cone for a given amount of current.
The cone or the wheel R-or both-should be covered with india rubber or other
suitable material, in order to ensure absence of slipping between the two.
In order to compensate for the variable attraction of the electro magnet A for
the armature B, I sometimes use a disc with a strap or chain carrying a weight as
shown in Figure 3; I key this disc excentrically on a horizontal axis so that as it
gets turned round by the action of the armature the leverage of the weight
increases, or I can make the latter constant and make the leverage of the armature
vary by this means.
Figure 4 represents an arrangement which may be substituted for the cone and
friction disc arrangement of Figures 1 and 2. The disc R on the shaft M revolves
in frictional contact with a disc S keyed on the shaft of a toothed wheel U, this
wheel is driven by a pinion V on the shaft N (the same as the N in Figures 1
and 2.
Although I have hereinbefore described that the working of the meter is controlled
by the position or motion of an armature due to the amount of current passing
-through-a-corresponding-electro-magnet,_it_is_evident that any other apparatus
which is similarly affected by the amount of current passing thorough it may be
employed such for example as a solenoid or a galvanometer.
Having now described the nature of my said Invention and in what manner the
same is to be performed I declare that I claim :-
First. The employment in electric-current meters of a magneto electric motor to
give constant or uniform rotary motion to a shaft which motion is transmitted at a
variable speed to the counting apparatus by gearing or mechanism controlled by
the armature of an electro magnet or analogous apparatus through which the
current to be measured passes substantially as hereinbefore described.
Second. Constructing electric current meters substantially as hereinbefore
described and represented in the annexed Drawings.
In witness whereof I the said St. George Lane Fox have hereunto set my
hand and seal this Twenty third day of June One thousand eight
hundred and eighty two.
ST. G. LANE FOX. (L.S.)