Improvements in Electric Measuring Instruments.
Year: 1896

page_text: Date of Application, 10th Oct., 1896
PROVISIONAL SPECIFICATION.
Improvements in Electric Measuring Instruments.
I, ARTHUR WRIGHT, of 26 Park Crescent, Brighton, Electrical Engineer, do
hereby declare the nature of this invention to be as follows:-
The object of my invention is to provide a simple form of instrument based on
the extension of wires due to their being heated by electric currents passing
through them for the purposes of measuring the quantity or pressure of an electric
current or for regulating electric currents.
My invention consists essentially of a method of supporting a light rod, herein-
after called the beam, held in position at one end by hinges, pivots, or springs,
and at the other by means of thin metallic wires which are so fastened or held in
a direction so as to form with the said rod a very small angle so that on the wires
expanding a very slight amount through being heated the wire-supported-end
of the index rod will fall a comparatively large distance, thus providing a method
for greatly magnifying a very small increase of length due to the heating of the
wires and the index rod can be thus made to measure by its movement the
temperature of the supporting wire which may be heated by the whole or part of
current which it is intended to measure or regulate.
For measuring the quantity of Electric currents which may be either alter-
nating or continuous the whole or part of them is sent through the supporting
wire or wires which are thereby caused to heat and expand, and thus allow the
index rod end to fall through a certain distance which will be dependent on the
quantity of the current passing through the wire. For measuring the pressure
or Difference of Potential of two points of an electric circuit, the wires are con-
nected to the two points either in series with other resistance or not, and the
current passing through the wire and the consequent movement of the rod will
be a measure of the Electric pressure between the two points.
By fixing a pen or point on the end of the beam, and placing this against.
a revolving cylinder of paper driven by clockwork or other suitable means, a
continuous record of all the movements, and thereby the currents,.may be made.
Again by making the moving end of the beam play between or against contact
points, the above instrument can be made to act as a relay to a regulator to keep
either pressure or the quantity of a current constant.
I prefer to make the beam of a material whose co-efficient of expansion is the
same as that of the wires.
For purposes of increasing the sensibility and openness and regularity of the
scale I sometimes prefer to make the above beam .actuate. a small magnifying
beam or lever moved by the principal beam through the medium of a roller link
or ligament and for the purposes of adjusting the instrument, I may adjust the
instrument by a suitable device for moving the fulcrum of the beam in relation
to the fixed supports of the wire.

page_text: When I use a subsidiary lever or beam, I ensure the scale being very open at
the part of the scale most likely to be used by so arranging the main beam and the
subsidiary beam as to ensure the former not coming into contact with the latter
until such part of the scale has been reached.
Dated this 9th day of October 1896.
I, ARTHUR WRIGHT, Electrical Engineer, 26, Park Crescent, Brighton, in the
County of Sussex, 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 object of my invention is to provide an improved forin of instrument based
on the extension of wires due to their being heated by electric currents passing
through them for the purposes of measuring the quantity or pressure of an electric.
current or for regulating electric currents.
My invention consists essentially of a method of supporting a light rod, herein-
after called the beam, held in position at one end by hinges, pivots, or springs
and at the other by means of a thin metallic wire or wires, which are fastened
or held on a framework pivoted or hinged at the other, end. The framework is
placed vertical to beam, and the point or points of suspension at which the wire
or wires are fastened or held are not in the same horizontal plane as that of the
fulcrum of the beam. The wire or wires being so fastened or held by the frame-
work at the moving end of beam form with the said beam a very small angle, so
that on the wire or wires expanding or contracting a very slight amount through
their being heated or cooled the wire supported end of beam will fall or rise a
comparatively large distance, thus providing a method for greatly magnifying a
very small increase or diminution of length due to heating or cooling of wire or
wires and the index rod can be thus made to measure by its movement the
temperature of the supporting wire which may be heated by the whole or part of
the current which it is intended to measure or regulate.
For measuring the quantity of Electric currents which may be either alter-
nating or continuous, the whole or part of such current is sent through the
supporting wire or wires which are caused thereby to heat and expand, and thus
allow the index rod to fall through a certain distance which will be dependent on
the quantity of the current passing through the wire. For measuring the pressure
or difference of potential of two points of an electric circuit, the wire or wires are
connected to the two points either in series with other resistance or not, and
the current passing through the wire or wires, and the consequent movement of
the rod will be a measure of the Electric pressure between the two points.
By fixing a pin or point on end of the beam and placing this against a
revolving cylinder of paper driven by clockwork or other suitable means a con-
tinuous record of all the movements and thereby of the currents may be
made..
Again by making the moving end of the beam play between or against contact
points, the above instrument can be made, to act as a relay to a regulator to
keep either pressure or the quantity of current constant.
I prefer to make the beam of a material whose co-efficient of expansion is the
same as that of the said wire or wires, or I may construct such beam of a com-

page_text: bination of materials in order to obtain a co-efficient of expansion corresponding
to the wires.
For purposes of increasing the sensibility, openness and regularity of the
scale, I sometimes prefer to make the above beam actuate a small magnifying
beam or lever moved by the principal beam through the medium of a roller link
or ligament. For the purposes of adjusting the instrument, I use a suitable
device for moving the aforesaid framework in a vertical plane relatively to the
base of instrument, thus tightening or slackening the supporting wires to the
required extent.
When I use a subsidiary lever or beam I ensure the scale being very open at
the part of scale most likely to be used by so arranging the main beam and the
subsidiary beam as to ensure the latter not being brought into contact with
the former until such part of the scale has been reached.
In order that my invention may be clearly understood I will now proceed to
describe the same with reference to the accompanying drawings.
Fig. 1 is a side elevation showing the working parts along with the subsidiary
lever with roller link for obtaining evenness at all parts of the scale.
Fig. 2 is a plan of working parts which are all fixed, with one exception,
namely, the subsidiary lever, on one side of instrument.
Fig. 3 is a view of front of instrument showing scale and head of adjustable
screw.
"A" is a metallic wire such as platinum, which is fixed at "B" and "B,"
and passes round the insulated pulleys "D" "C" "D."
"" is a framework pivoted at "T" and supporting the pulleys "B" "C"
"B," which are all in the same horizontal plane."
"E" is a light compound tube having the same co-efficient of expansion as the
wire. It is hinged at "H" and supported at other end by wire "A," the mean
plane of which wire forms a small acute "L" with beam "E."
The current enters at terminal "O," passes through the wire causing it to
heat and consequently expand, and by the arrangement herein described a very
small increase in length of wire is greatly magnified at "K."
"J" is a subsidiary lever for further multiplying the original movement and
also for producing a more even scale at any desired point. The latter is done by
means of a roller link which when fastened on lever "J" and rolling on
plane "K" causes the distance between the fulcrum "V" and the point of
application of power on plane "K" to be varied so as to give a more even
scale.
"M" is a rod by means of which the framework "F" is actuated in a vertical
plane thus permitting the subsidiary lever "J" to be brought into action by the
beam "E" after a certain percentage of current capacity of instrument has
passed.
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 Electrical Measuring Instruments the method described of obtaining a
large movement of an indicating beam from a small expansion of an electrically
heated wire or wires, by supporting the moving end of the said indicating beam
by the said wire or wires in such a manner that the latter are held in such a
direction as to form a suitably acute angle with the line joining the centre of
motion of the said beam and its end supported by the wire or wires.
2nd. In Electrical Measuring instruments the method of further multiplying
the original movement and also of producing a more even scale by use of a
subsidiary lever as herein described by means of which the distance between the
fulerum of the secondary lever and the point of application of power on the wire
supported end of principal beam is altered so as to give a more even scale.
3rd. In Electric Measuring instruments the method of construction herein des-

page_text: cribed by which the secondary lever is only brought into action by the principal
beam, after a certain percentage of current capacity of instrument has passed
through the supporting wire, thus giving a very open scale at any desired point.
Dated this 9th day of August 1897.
ARTHUR WRIGHT.