IMPROVEMENTS IN INSTRUMENTS FOR MEASURING ELECTRIC CURRENTS
Year: 1887

page_text: Date of Application, 21st Mar., 1887
Complete Left, 21st Jan., 1888
Complete Accepted, 21st Mar., 1888
I JOHN WILLIAM KING of 13 St. John Square Clerkenwell in the County of
Middlesex Electro-metallurgist do hereby declare the nature of said invention for
IMPROVEMENTS IN
INSTRUMENTS FOR MEASURING ELECTRIC CURRENTS to be as
follows:-
This invention has for its object improvements in Instruments for measuring
Electric currents and consists in dispensing with a permanent magnet and making
the strip or strips of a form hereinafter described for effecting the objects of these
improvements.
The usual form of Am-meter or Volt-meter is by the employment of coils of wire
but according to this Invention I employ a strip or strips of suitable metal acting as
the conductor.
The bottom pivot of the needle is at A Fig. 1, and this is surrounded at a convenient
distance by the strip or sheet metal conductor, the central opening in the same being
of a suitable size and shape. I do not confine myself to the exact size or shape of
this strip or strips as shown in the drawings as I may slightly alter them to suit
requirements.
In Fig. 2 I have shown another form of strip B which is turned over in the manner
shown and the terminals attached at each end of the strip in a similar manner to the
single strip before referred to.
It will thus be observed that owing to the shape and disposition of the conducting
strip promptness and vigour of action are secured thus ensuring direct proportionality
of angle of deflection to the current passing.
In am-meters or volt-meters where a counterpoise is applied to the opposite end of
the needle I have found that a vertical alteration of this counterpoise will cause the
alteration of leverage and a consequent change in the value of the reading according to
special divisions on the dial for the purposes required of it. The needle is advan-
tageously of wire and carries at the one end the counterpoise. The needle passes
D

page_text: through the axis, cap, or equivalent device and the needle can be secured therein in
the predetermined position by any suitable means.
In a similar manner a flat needle
can be employed. By this means an am-meter or volt-meter can be altered to read
from 0 to 100 or in a similar division to read from 0 to 50 or any other No. of reading
simply by the vertical rise or lowering of the needle as may be required. The counter-
poise is the controlling force acted on by gravity or it may be any other suitable
controlling force.

page_text: COMPLETE SPECIFICATION.
Improvements in Instruments for Measuring Electric Currents.
I JOHN WILLIAM KING of 13 Saint Johns Square, Clerkenwell, in the County of
Middlesex, Electro Metallurgist, do hereby declare the nature of said Invention for
IMPROVEMENTS IN INSTRUMENTS FOR MEASURING ELECTRIC CURRENTS and in what
manner the same is to be performed to be particularly described and ascertained in
and by the following statement :-
This invention has for its object improvements in Instruments for measuring
Electric Currents and consists in dispensing with a permanent Magnet and making
the strip or strips of a form hereinafter described for effecting the object of these
improvements.
The usual form of Am-meter or Volt-meter is by the employment of coils of wire, but
according to this invention I employ a strip or strips of suitable metal acting as the
Conductor. The bottom pivot of the needle is at A Fig. 1 and this is surrounded at
a convenient distance by the strip or sheet metal conductor B the central opening in
the same being of a suitable size and shape. I do not confine myself to the exact
size or shape of this strip or strips as shewn in this figure as I may slightly alter
them to suit requirements. Modifications of these figures being shewn at Figures 2.3.
4. 5. 6. 7. 8. and 9 of the drawings annexed.
In Fig. 2 the strip B is turned over in the manner shown to form a double strip
and the terminals attached at each end of the strip in a similar manner to the single
strip before referred to.
It will thus be observed that owing to the shape and disposition of the conducting
strip promptness and vigor of action are secured, thus ensuring direct proportionality
of angle of deflection to the current passing.
In Am-meters or Volt-meters where a counterpoise is applied to the opposite end
of the needle or pointer I have found that a vertical alteration of this counterpoise
will cause the alteration of leverage and a consequent change in the value of the
reading according to special divisions on the dial for the purposes required of it as
shewn in the Fig. 1. The pointer is advantageously of wire and carries at the one
end the counterpoise. The pointer passes through the axis, cap or equivalent device
and can be secured therein in the predetermined position by any suitable means.
a similar manner a flat pointer can be employed. By this means an Am-meter or
Volt-meter can be altered to read from 0 to 100 or in a similar division to read
from 0 to 50 or any other No. of reading simply by the vertical rise or lowering of
the pointer as may be required. The counterpoise is the controlling force acted on
by gravity, or it may be any other suitable controlling force.
In
In Fig. 1 I have shewn two scales of reading the pointer in. This example being at
the lower scale and when it may be desired to read on the upper scale, the pointer
and with it the counterpoise or other controlling force is raised to the position
required, for example to A in the case of a counterpoise as shewn in the dotted lines
at Fig. 10.

page_text: Having now particularly described and ascertained the nature of my said Inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is-
1st. In Instruments for measuring electric currents the employment of a strip or
strips of metal of a shape approximating to those illustrated in the accompanying
drawings whereby their shape and disposition ensures promptness and vigor of action
together with direct proportionality of angle of deflection to the current passing as
herein set forth.
2nd. In Instruments for measuring Electric. currents the method and means for
effecting the vertical alteration of the needle in combination with a second or more
set of readings substantially as herein set forth and illustrated with reference to the
accompanying drawings.