Improvements in Apparatus for Measuring Electric Currents.
Year: 1889

page_text: Date of Application, 8th Feb., 1889
Complete Specification Left, 8th Nov., 1889-Accepted, 14th Dec., 1889
PROVISIONAL, SPECIFICATION.
Improvements in Apparatus for Measuring Electric Currents.
JOHN WILLIAM KING 13 St. John's Square Clerkenwell London E.C. Electro
Metallurgist do hereby declare the nature of this invention to be as follows:-
In constructing an instrument for measuring electric currents according to this
invention I take a piece of iron or steel of a spiral form A in the drawing and attach
it to the spindle or pivot P by one end the other end being free to revolve above or in
front of the electro magnet NS; when at rest and the index D pointing to zero on
the dial (not shown) the position of the spiral needle is determined by the force of
gravity or a spring in any of the useual ways.
When a current of electricity is passed through the electro magnet it attracts the
spiral needle and the part of the iron needle nearest the core of the magnet is pulled
round till the extreme lowest end of the needle is over the iron core if the current of
electricity is strong enough.
If the current is not strong enough to do so it will pull it round a distance corre-
sponding to the strenght of the current and the pointer will mark the same in degrees
or other divisions on a dial graduated for that purpose.
I do not limit myself to this mode of fixing needle or this exact form, as the needle
may be a piece of iron or steel wire wound spirally round a piece of vulcanite, wood,
brass or other substance.
Or it may be a flat iron piece twisted round the spindle like the thread of a screw.
Neither do 1 limit myself to this exact form or position of electro magnet as it
may take the form of a solenoid entirely surrounding the needle.
Dated this Bighth day of February 1880
COMPLETE
SPECIFICATION.
Improvements in Apparatus for Measuring Electric Currents.
JOHN WILLIAM KING 13 St. John's Square Clerkenwell London Electro Metal-
lurgist 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 :-
In constructing an instrument for measuring currents of electricity according to
this invention I take a piece of iron or steel of a spiral form A in the drawing left
with the provisional Specification and attach it to the spindle or pivot P by one end,
the other and being free to revolve above the electro magnet C. When at rest and
the index D is pointing to zero on the scale of the instrument (not shown) the position
of the spiral needle is determined by gravity or a spring in any of the useual ways.
When a current of electricity is passed through the electro magnet it attracts the
spiral needle and the part of the needle nearest to the iron core or pole piece of the
magnet is pulled round till the extreme end of the needle is over the iron core or pole
piece of the electro magnet that is providing the current of electricity is strong
enough. If the current is not strong enough to do this it will be pulled round a
distance corresponding to the strength of the current and the pointer will mark the
same in degrees or other divisions on a dial graduated for that purpose.
I do not limit myself to this mode of fixing the needle or this exact form the needle
may be a piece of wire of any magnetic material wound spirally round a piece of
vulcanite wood brass or other substance.
Or it may be a flat piece twisted round the spindle or pivot like the thread of a
Icrew

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 1 declare that what I
claim is
The spiral shape of needle which may be of any section and placed in any position
relative to the electro magnet and pole piece which may be found best for the special
purpose for which the instrument is used.
Date the Eighth inve of Vo 1400