Improvements in Prepayment Electricity Meters.
Year: 1898

page_text: Date of Application, 25th June, 1898-Accepted, 13th Aug., 1898
COMPLETE SPECIFICATION.
Improvements in Prepayment Electricity Meters.
We, FRANCIS MADDISON LONG, of 12, Mile End Road, and ERNEST SCHATTNER,
of 78, Mill Hill Road, both of Norwich, in the County of Norfolk, Electrical
Engineers, do hereby declare the nature of this invention and in what manner
the same is to be performed, to be particularly described and ascertained in and
by the following statement:
Our invention relates to certain improvements in prepayment electricity meters
or electricity meters of the class controlled by the insertion of a coin or coins
which places certain parts of the apparatus in position to allow a current to pass
through same for a given period of time only.
In carrying out our invention we utilize the principle that a current going
through a voltameter deposits on one plate of same from the other a quantity
of metal exactly proportionate to the strength of the current by causing one plate
to be carried by a balanced arm which is overbalanced by the weight of the coin
or coins so as to make an electrical contact whereby a current will pass through
the voltameter until a certain amount has been deposited from or on the plate
carried by the arni onto or from a fixed plate with the result that the plate so
carried is lightened or made heavier and the arm rises thus breaking the circuit.
One form of apparatus constructed according to our invention is illustrated
in the accompanying drawing which is an elevation showing the main or principal
features of such an apparatus.
On a suitable back or base a and properly insulated is an arm or lever b sup-
ported by a suitable knife edge or the like situated slightly below the centre of
gravity of the lever so that the lever is in unstable equilibrium and remains over-
balanced either on one side or the other.
The knife edge or the like is carried on the block c and directly above and
attached to the lever is a rod d having a weight at the end which assists in over-
balancing the lever. At one end the lever carries a screw e provided with a nut
or weight by which the balance of the lever may be adjust and also a rod g
preferably suspended to it on a knife edge and carrying weights h. A stop
secured to the base serves to check the downward movement of the arm.
On the other side of the block c is a receptacle j for the coins preferably suspended
on a knife edge to the lever as shown and further along the arm, and on the same
side of the pivoting point as the receptacle jis suspended a rod k adapted to carry
weights representing a certain number of coins. This rod is also preferably hung
on a knife edge. At the extreme end is hung the positive electrode m of the
voltameter n such electrode being also preferably carried by a knife edge in some
suitable way.
As shown it is attached
The negative electrode o is fixed in some suitable way.
to the base a at point p. The electrodes may be of copper in which case the
solution will be also a copper one.

page_text: The lever also carries at or about the same end a contact maker of some suitable
form. As shown it consists of a U shaped or bifurcated strip q suitably insulated
from the lever the ends of such strip dipping into mercury cups rs the former of
which is a terminal of the main wire and the latter a terminal of wires u and u¹
the first of which leads through resistance v to the main terminal w the latter leads
to the fixed plate o of the voltameter through point p and connection is provided
from the suspended plate m through the lever b to the block c and thence by the
wire u and a resistance v also to the main terminal w.
The operation is as follows:-The lever is to start with, just overbalanced, and
the contact maker q is out of the mercury of the cups rs and the circuit is broken.
Upon a coin or coins being dropped into the receptacle j the lever is overbalanced
at that side and the contact maker is placed in the mercury of the cups as shown
in the drawing. The current entering at terminal w divides, part passing through
resistance v wire u block c lever 6 positive electrode m to negative electrode o out
by terminal p wire u¹ to mercury cup s contact maker cup and out, and part
going through resistance and wire u and joining the other circuit at cup s.
Copper from electrode m is thus deposited on o proportionately to the current being
used and as soon as electrode m is sufficiently lightened the lever b will rise and be
again overbalanced and the contact maker be removed from the mercury so that
the circuit is broken until another coin or coins is inserted in the receptacle.
The rod k is adapted to carry discs or weights equal to a certain number of coins
one or more of which weights can be placed thereon by the collector to balance the
coins taken from the receptacle.
It will be understood that the particular arrangement of the apparatus may be
varied without departing from our invention for instance instead of restoring or
putting the parts in working position by placing a coin in a receptacle which
directly overbalances the lever the coin may be caused to move a weight or allow
a weight to be moved along the lever, the lever being graduated if necessary or to
vary the weight on the lever or the like.
It should also be understood that with the apparatus herein described there may
be combined a suitable counting and registering device which will indicate
the number of coins inserted as well as suitable means for preventing the with-
drawal of coins or the insertion of improper articles if deemed necessary all of
such arrangements being of a well known character.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, we declare that what
we claim is;-
1. A prepayment electricity meter operated by a coin or coins caused to move
a lever and thus make a circuit through a voltameter, one of the electrodes of
which is carried by said lever, until the deposition from or into such electrode
has so decreased or increased its weight that the lever is raised and thereby breaks
the circuit, substantially as described.
2. A prepayment electricity meter operated by a coin or coins which overcome
the balance of a lever or allows the balance to be overcome and thus make a circuit
through a voltameter one of the electrodes of which forms part of the balancing
means of same, until the deposition from or onto such electrode has so decreased
or increased its weight that the lever is again overbalanced and the circuit is
broken substantially as described.
3. In a prepayment electricity meter the combination with a lever having its
centre of gravity above the centre of oscillation of a voltameter and a contact
breaking device operating substantially as and for the purpose described.
4. A prepayment electricity meter comprising a balanced lever a voltameter
an electrode of which is carried by said lever a contact maker operated by the lever
a receptacle for the coins on the lever and a compensating device on the lever to
balance the coins removed all substantially as and for the purpose described.

page_text: 5. The combination with an electricity meter as described in the preceding claim
of a counting and registering device to record the number of coins inserted substan-
tially as described.
6. A prepayment electricity meter substantially as described and illustrated in
the accompanying drawing.
PHILIP M. JUSTICE,
55 and 56, Chancery Lane, London,
Chartered Patent Agent for the Applicants.