Year: 1888

page_text: WALTER HIBBERT, 8 St. Dunstans Road West Kensington London, Chemist do
ereby declare the nature of this invention to be as follows:-
The measurement of electrical current, electro-motive force etc., by arranging the
conductors and a magnet or magnets, so that only one kind of pole is acted upon, or
if the two poles be brought into action, causing the current to flow in opposite
directions past them.
In one form of instrument, two magnets are suspended vertically, parallel to one
another, with their north poles downwards. Midway between them rises the conductor,
a vertical wire, conveying the current parallel to the magnets until it reaches the
equatorial region or middle of the magnets, where it is bent at right angles so as to
run in a horizontal direction. The two magnets are held above by a disc carrying an
agate cup which rests on a needle point. The disc carries a pointer moving in
a horizontal plane over a scale, and there is also attached to it, the lower end of a
controlling spring. When a current flows in the conductor, it acts on the two
North poles only, and on them in the same direction as far as rotation is concerned.
In rotating, the poles remain at the same distance from the wire, & therefore give
deflections of the pointer proportional to the currents acting on them.
In another form of instrument, the same arrangement of two vertical and parallel
magnets, having their north poles downwards, is pivoted so that these north poles
are slightly above the surface of a horizontal disc, and centrally placed with reference
to it. The current is made to flow, by any suitable arrangement, from the circum-
ference to the centre of this disc. The forces produced by the radial currents in the
disc act on the two North poles above it, so as to produce rotation, which is indicated
by a pointer attached to the magnets.
Weak currents may be measured by suitable arrangement of the conductors. For
example, in the second form described above, the disc may be replaced by a flat ring
wound continuously with insulated fine wire, so that the current flows in all the
convolutions radially from circumference towards the centre.

page_text: The springs used in these and other analogous forms, may be replaced by a
torsion wire or other controlling arrangement, and the magnets may be supported
horizontally instead of vertically, the other parts being arranged accordingly.
Some forms of the instrument, as for example the second one described above,
allow of continuous rotation of the magnetic system, & therefore of measuring the
total quantity of electricity passing through during a given time.
101
T
1000
COMPLETE SPECIFICATION.
Improvements in Electrical Measuring Instruments.
I, WALTER HIBBERT, of 8 St. Dunstans Road, West Kensington, London, Chemist,
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 :-
This invention for Improvements in electrical measuring instruments relates to
instruments of the class known as Ammeters or voltmeters, and which are used for
measuring electric currents, electro motive force etcetera, and consists essentially of
arrangements and devices by which practically only one pole of a magnet or magnets
is acted on by the current to be measured, and in so arranging this one pole that its
distance from a certain part of the conductor conveying the current to be measured
remains constant however much the magnet may be deflected.
In the accompanying sheet of illustrative drawings, Fig. 1 is a sectional elevation
of one form of instrument constructed according to this invention, and,
Fig. 2 is a horizontal section at the line A. B. fig. 1.
A base a adjustable horizontally by means of the thumb screws b has secured to it
the frame c d e through which passes a conductor fg having its vertical limb f
secured to but insulated from the horizontal part e of the frame; the horizontal limb g
of the conductor passes through but is insulated froin the vertical part d of the frame
as clearly shewn. The extremities of the conductor, the current Howing in which is
to be measured are connected to the two terminal screws. To the upper part of
the vertical limb f is fixed a needie or pivot k, supporting an agate cup carrying a
horizontal cross bar m to which is rigidly secured the vertical magnet is having its
lower end fixed in a carrier plate o to guide it, and to insure its rotation around the
limb of the conductor and at a constant distance from it.
The system is balanced in a vertical plane by means of the adjustable screw
weight p, and a pointer is provided for indicating on a horizontal scale the
deflections of the ua net. The necessary resistance to rotation is provided by the

page_text: spring & connected to the bar m and to the adjusting screw
bracket u.
WHICH
ULIC
As the vertical limb f of the conductor terminates at about the middle of the
magnet n. s it will be obvious that the upper pole is almost entirely outside the active
influence of the current flowing in the conductor.
The frame e de constitutes preferably a strong permanent magnet which assists in
maintaining constant the magnetism of the magnet is.
When a current flows through the conductor fy it acts upon the magnet ns causing
it to rotate around the vertical limb of the conductor, and, as in such rotation the
magnet remains at a uniform distance from the said vertical limb of the conductor,
the angular deflections, which are denoted by the pointer q attached to the bar mare
directly proportional to the strength of the current.
Fig. 3 represents in skeleton or diagramatic elevation a modified arrangement of
instrument, in which two magnets n. 8 are suspended with their similar poles down-
wards from a bar m supported by a needle k. The magnets are both parallel to and
equidistant from the vertical part of the conductor fg, their upper poles being
removed almost entirely outside the range of action of the current.
Fig. 4 shews in elevation another modification in which a horse shoe shaped
magnet ns is pivoted on the needle point k in such a manner that the two limbs are
parallel to the vertical part of the conductor; but one pole being much nearer than
the other. The deflection is that due to the difference of the two forces acting on the
two limbs of the magnet. It will be obvious that where preferred both poles may be
placed on the one side of the conductor.
Fig. 5 shews an arrangement with horse shoe magnet, one pole only of the magnet
being acted on.
Fig. 6 represents an arrangement in which a hollow steel cylinder n. s is magnetised
axially, the whole of each end forming one pole, and is supported by the needle
point. The conductor is fixed so that the vertical part f is nearer to the lower
end, which is therefore the part principally influenced by the current. As the cylinder
rotates fresh portions of the magnetised surface come opposite the effective part of
the conductor and at the same distance therefrom.
Instead of placing the effective part of the conductor parallel to the side of the
cylinder it may be placed at an angle, or parallel to the end.
In another form of instrument, the same arrangement of two vertical and parallel
magnets, having their similar poles downwards is pivoted so that these similar poles
are slightly above the surface of a horizontal disc, and centrally placed with reference
to it. The current is made to flow, by any suitable arrangement, from the circumi-
ference to the centre of this disc. The forces produced by the radial currents in the
disc act on the two similar poles above it, so as to produce rotation, which is indicated
by a pointer attached to the magnets.
Fig. 7 shews a modification for the measurement of weak currents, in which two
magnets n. & are suspended from the point with their lower poles over the upper
surface of an annular ring a which is wound radially with fine insulated wire, the
ends being terminated by the binding screws b. The current flows in all the
convolutions radially from the circumference towards the centre.
The springs used in the above described instruments may be replaced by a torsion
wire or other controlling arrangement, and the magnets may be supported horizontally
instead of vertically the other parts being arranged accordingly.
It will be obvious that many modified arrangements of the instruments besides
those illustrated may be adopted without departing from the nature of my invention.
In all the hereinbefore described arrangements it has been assured that permanent
magnets were employed, but it will be obvious that the working magnet may be
constructed of wrought iron, and the necessary magnetic condition induced by
powerful inducing or held magnets suitably disposed.
When it is desired to construct these instruments as voltmeters, the thick conductor
marked f g on the drawing must be replaced by a thin conductor wound continuously
into many convolutions.

page_text: Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
1 claim is
1. In electrical measuring instruments: Arranging the working magnet or magnets
parallel to a certain part of the conductor conveying the current to be measured, so
that the magnet or magnets when rotated remain parallel to and at a constant
distance from the said conductor, and so that one pole only of the magnet, or similar
poles of the magnets are principally influenced by the current in the said part of the
conductor substantially as described.
2. The arrangement and construction of electrical measuring instruments sub-
stantially as described with reference to figs. 1 and 2 of the drawings.
3. The arrangement and construction of electrical measuring instruments sub-
stantially as described with reference to the modifications shown in figs. 3 and 4 and 5
and 6 and 7 of the drawings.
Dated this 19th day of November 1988
WHEATLEY & MACKENZIE,
156, Strand, W.C.,
Agents.