Improvements in Instruments for Electric Measurement.
Year: 1887

page_text: Date of Application, 30th July, 1887
Complete Left, 14th Apr., 1888
Complete Accepted, 18th May, 1888
PROVISIONAL, SPECIFICATION.
Improvements in Instruments for Electric Measurement.
We WALTER EMMOTT Electrical Engineer and JOHN HALL RIDER Electrician both
of the Northern Telegraph Works, Halifax in the County of York, do hereby declare
the nature of this invention to be as follows: :-
The Invention relates to improvements whereby Electric current or potential can
be accurately measured and consists of a soft iron needle free to move in a magnetic
field and made of such a form that varying quantities of iron are brought into the
field as the strength of the said field is varied. Any variation of strength of field
causes the needle to rotate on its axis without altering its distance as a whole from
the magnetic poles. This we accomplish by making the outer edge of the needle of a
circular form while the thickness varies-The rotary movement of the needle is
counteracted by gravity or a spring or other suitable means in the usual manner.
WALTER EMMOTT.
JOHN HALL RIDER.

page_text: COMPLETE SPECIFICATION.
Improvements in Instruments for Electric Measurement.
We WALTER EMMOTT and JOHN HALL RIDER Telegraph Engineers both of The
Northern Telegraph Works, Halifax in the county of York 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 :-
The invention relates to improvements whereby electric current or potential can bo
accurately measured, and consists of a soft iron needle free to move in a horizontal or
vertical plane in a magnetic field, and made of such a form, that varying quantities of
iron are brought into the field, as the strength of such field is varied.
Any variation of strength of such field causes the needle to rotate on its axis,
without altering its distance as a whole from the magnetic poles.
This we accomplish by making the outer edge of the needle of a circular form,
while the thickness varies.
The rotary movement of the needle is counteracted by gravity, or a spring or other
suitable means in the usual manner.
DESCRIPTION OF DRAWINGS.
Fig. 1 is a plan of a volt meter with our improvements applied.
Fig. 2 is a section of Fig. 1, on the line A. B.
Figs. 3, 4, and 5 show plans and sections of various shapes of needles.
N is the needle, and P and P¹ are the pole pieces, which act upon the needle N, in
the usual manner. S is the spring used to bring the needle to Zero, this spring may
be replaced by a counterpoise or other suitable equivalent.
The needles shown at Figs. 3, 4, and 5, are well adapted for instruments such as
Volt Meters, Watt Meters, Am Meters, Ohm Meters, and the like.
T. and Tare the terminals.
Having now particularly described and ascertained the nature of this invention and
in what manner the same is to be performed we declare that what we claim is :-
..In electrical measuring instruments the use of a needle, so formed, that its edge is
of circular form, and of varying thickness of metal for the purposes set forth.
JOHN E. WALSH,
Crossley Street, Halifax,
Agent for the Applicants.
JOHN E. WALSH,
Crossley Street, Halifax,
Agent for the Applicants.