Improvements in Electrical Measuring Instruments.
Year: 1898

page_text: Date of Application, 22nd Mar., 1898-Accepted, 19th Nov., 1898
COMPLETE SPECIFICATION.
Improvements in Electrical Measuring Instruments.
I, EDWARD WESTON, of No. 114, William Street, Newark, in the County of
Essex and State of New Jersey, United States of America, Electrician, do hereby
declare the nature of this invention and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement:
My invention is directed to improvements in and relating to electrical measur-
ing instruments and its objects are:-
First, to devise instruments which shall be compact in structure and especially
adapted for commercial use; Second, to so construct the movable parts of such
instruments that they shall be as light as possible, arranged within as strong
an electrostatic field as can be attained and all effectively insulated from the
enclosing casing; Third, to devise a switch which shall render it possible to
simultaneously electrostatically charge the quadrants of the instrument and the
movable armature or needle; and discharge the same in as simple and positive
a manner as possible; Fourth, to arrange such switch in a chamber or case
independent from, but substantially integral with, the case which encloses the
instrument whereby any damaging arc effects which might result from short cir-
cuits at the switch will prevent any possibility of injuring the delicate parts of
the instrument itself; and Fifth, to provide stable or permanent means for bring-
ing the electrostatic armature or needle to rest as quickly as possible after it
and its controlling quadrants have been subjected to a charge.
My invention will be fully understood by referring to the accompanying
drawings, in which,
Figure 1 is a plan view of my improved electrometer the top of the casing
being removed in order to better disclose the interior structure thereof; and,
Figure 2 is a longitudinal sectional view taken through the casing of the
instrument and showing the interior structure of the operative parts thereof in
elevational view as seen looking at Figure 1 from the left toward the right hand
side of the drawings.
Figure 3 is a part sectional part elevational view taken through the instrument
and as seen looking at Figure 1 from the bottom toward the top of the drawings,
a part only of the enclosing case being shown in sectional view and one of the
supporting standards broken away.
Figure 4 is a plan view of the electrostatic armature or needle which controls
the movable parts of the instrument.
Figure 5 is a vertical sectional view of the hollow pivot shaft which supports
the electrostatic armature or needle and the index needle, a part of each of said
needles being shown in position, the manner of securing the same to the shaft
being also illustrated.
Figure 6 is a sectional view taken through the body of the switching chamber
or casing and illustrating the switch-controlling mechanism, partly in sectional

page_text: and partly in side elevational view, the binding posts of the instrument being
also shown in elevation.
Figure 7 is a similar detail view showing the switch in closed position; and
Figure 8 is a diagrammatic view showing the circuit connections between the
binding posts, the switch, the quadrants and the electrostatic armature or needle
of the instrument, the index needle being also shown.
Referring now to the drawings in detail, in all of which like letters of refer-
ence represent like parts wherever used, for a full and clear understanding of
my invention such as will enable others skilled in the art to which it relates to
construct and use the same.
C² represents the enclosing casing of the instrument which is preferably of cast
iron and having the conformation shown in Figures 1 and 2, C3 being a down-
wardly extending portion of cylindrical form for enclosing the major portion of
the operative parts.
E is a chamber or casing for enclosing the controlling switch and in the
present instance is cast integral with the chamber C3 which encloses the instru-
ment proper and has an opening into the latter to enable the conductors to be
properly connected up with the stationary and movable parts of the instrument,
as will be described more particularly in connection with Figure 8 of the
drawings.
B¹ is a base of insulating material preferably of hard rubber or vegetable fibre
secured to the bottom of the cylindrical part C³ by screws $2.
QQ and Q Q are four independent quadrants constructed, preferably, each
of two thick sheets of brass accurately turned or dressed in such manner that
when placed together in the position shown in Figures 1 and 3 there is left
between them an open disk-like field within which the quadrants Q Q of the
electrostatic armature or needle N revolves.
a is a hollow or tubular pivot shaft made preferably of aluminum and screw-
threaded interiorly and exteriorly at its opposite ends for the purpose of receiving
pivot pins p p and clamping nuts n² n² n³, the lower nut n² of the pair at the
upper end being of insulating material, preferably ivory, and the upper nut n²
of metal adapted to hold an aluminum index needle I and spiral springs in
position; m being a sheet of mica for insulating the needle I from the shaft a,
while the lower nut is adapted as shown to hold or secure the electrostatic
armature or needle N, made preferable of a sheet of aluminum and having quad-
rant form QQ, as shown in full-sized view in Figure 4.
jjare jewel bearings for the pivot pins pp, one of said bearings being
secured in the insulating base B¹ and the other at the centre of an electrical
conducting bridge piece b¹, preferably of brass supported upon standards S S¹,
nnn being nuts for securing these parts together.
W, see Figure 3, is an angular shaped conducting arm secured to the under-
side of the bridge piece b1, its function being to furnish mechanical electrical
connection between the spirally disposed springs and the pivot shaft a.
The index needle I is provided at one end with a pointer adapted to move
over a scale properly calibrated to indicate the readings for which the instru-
ment is constructed and its other end is flattened in the manner shown at w in
Figures 1 and 8 for the purpose of serving as a counter-weight.
ee are metallic buffer springs secured by insulating blocks h h and screws to
the inside of the instrument case and provided at their free ends with down-
wardly extending insulating sleeves el e located in the path of the index needle I,
see Figure 2, their function being to prevent any possibility of damage to the
delicate indicating needle I in the event of a sudden throw thereof to either side
on connecting it, the instrument, in circuit, said dampening springs being elec-
trically insulated for the purpose of preventing any possible escape of the
statical charge from the electrostatic needle N when the instrument is in use.
M M are permanent magnets secured to the insulating base B₁ in such manner
that their polar ends establish a magnetic field about one end of the quadrant-

page_text: shaped armature or needle N, their function being to produce a dampening effect
thereon and cause the same to settle quickly after the instrument has been
connected in circuit with the source of electrical energy, the potential of which
it is desired to ascertain.
I is a second index needle or hand which is pivotally secured to the under-
side of the lid L of the instrument case and is provided with an operating
handle H for mechanically setting the pointer of said needle at any point of
the scale, see Figures 1 and 2, in order that the same may display to a person
at a distance some fixed point thereon with relation to which it is desired to
compare the movements of the index needle I when actuated by the current.
The switch chamber E is provided with a removable lid F of hard rubber,
vegetable fibre, or like insulating material to the underside of which is secured,
by screws, two curvilinear switching contact springs tt resting normally
against each other when the instrument is out of circuit, as clearly shown in
Figures 6 and 8, B and 13 being binding posts provided with hard rubber covers
of well known form and having their inner or metallic terminals located in the
path of the free ends of the switching springs t t. W₁ W being insulating
washers for insulating the operative parts of the instrument from the enclosing
metallic casing.
Z is a switch actuating pin of insulating material provided with an insulating
head or knob K, said pin being secured in the insulating cover by a screw-
threaded socket or sleeve, and d'is a retractile spring for normally holding it in
the position shown in Figure 6. 7 is a metallic pin extending through the
insulating pin Z, and g is a double inclined groove in the lower part of the
socket or sleeve which supports the switching pin, the arrangement being such
that when the head K is forced downward and turned 90° as shown in Figure 7,
it will remain locked in its lower position with the outer ends of the pin I
resting against the lower end of the socket or sleeve, while the contact springs t
and are simultaneously forced outward against the inner ends or terminals of
binding posts B B¹.
Referring now to Figure 8, for a full and clear understanding of the circuit
connections of the instrument.
B B represents the binding posts of the instrument as before and t t the
switching springs. To the upper ends of these springs are secured insulated
conductors w and which pass therefrom through an opening or openings in
the partition between the two enclosing chambers E and (3, the conductor l
dividing into two branches running respectively to the two oppositely disposed
quadrants QQ, the conductor into three branches, two of which 2 run
to the oppositely disposed quadrants Q2 Q2, located between the before-mentioned
quadrants QQ, while the third branch 3 runs to the electrostatic armature or
needle N, the circuit being through the bridge piece 1, Figure 3, the angular
arm W, spiral springs, pivot shaft a to the quadrants QQ.
The operation is obvious on inspection of Figure 8. it being apparent that if
the switch K he forced downward and the binding posts B and B be connected
respectively to the positive and negative poles of an electrical generator, the
voltage of which it is desired to measure, supposing the instrument to be cali-
brated for a voltmeter, the two quadrants QQ will be charged positively, the
two quadrants Q3 Q2 negatively, while the two quadrants QQ of the electrostatic
armature or needle N will also be negatively charged, thereby causing the index
needle I to vibrate from left to right and indicate upon the scale. Figure 1.
the voltage of the current to be measured. The indicating needle I will be
caused to settle immediately by virtue of the action of the magnetic field due to
the permanent magnets M M upon the lower quadrant Q of the propelling electro-
static armature or needle.
I do not limit the hereinbefore disclosed improvement to the particular details
of structure shown and described. as it is obvious that the same may be departed
from in many respects and still come within the scope of my claims hereinafter

page_text: made. Nor do I limit the use of the improvements to electrometers, as it is
apparent that many of the details of structure herein before described might be
adopted in connection with various forms of electrical measuring instruments
and my claims are designed to include all such uses.
I believe it is broadly new with me to combine the stationary and movable
parts of an electrostatic measuring instrument in a compact form which will
adapt it for commercial use, and to enclose the same within a metallic casing,
the operative parts of the instrument being wholly insulated from such casing
so that there is no possibility of discharging the instrument in the event of
the casing coming into contact with a conductor connected with a surface or body,
such for instance as the earth, having lower potential than the charging source,
and my claims are generic as to this feature.
I believe it is also broadly new with me to arrange the switching contacts of
an electrical measuring instrument in a chamber or casing independent from,
but substantially integral with, the chamber or casing which encloses or sur-
rounds the operative parts of the instrument.
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
I claim is:
1. An electrometer having its quadrants so arranged as to constitute a disc-
like field, in combination with a disc-like armature or needle adapted to rotate
in said field and sustained upon a pivot shaft, all of said parts being insulated
from a surrounding metallic casing, substantially as described.
2. An electrometer having its quadrants so arranged as to constitute a disc-
like field, in combination with a disc-like armature or needle and an index
needle supported by a pivot shaft, all of said parts being electrically insulated
from a surrounding metallic casing, substantially as described.
3. An electrometer having its quadrants so arranged as to constitute a disc-
like field, in combination with a disc-like armature or needle and an index
needle supported by a pivot shaft, together with buffer springs and an enclosing
or surrounding casing, all of said parts being electrically insulated from said
casing, substantially as described.
4. An electrometer consisting of stationary and movable electrostatic parts,
and an indicating needle for the movable part, all of said parts being wholly
enclosed in a metallic casing and electrically insulated therefrom, substantially
as described.
5. An electrometer consisting of a stationary and movable electrostatic parts
wholly enclosed within a metallic casing and electrically insulated therefrom, the
movable parts being made of aluminium, substantially as described.
6. An electrometer consisting of stationary and movable electrostatic parts,
in combination with magnetic means for establishing a magnetic field about the
movable part in such manner as to exercise thereon a dampening effect, sub-
stantially as described.
7. An electrometer consisting of stationary and movable electrostatic parts
and an index needle operatively connected to the movable part, together with
magnetic means for establishing a magnetic field around the movable part, all
of said parts being enclosed in a metallic casing and insulated therefrom sub-
stantially as described.
8. An electrical measuring instrument provided with a fixed and movable part
enclosed in a metallic casing, in combination with a circuit controlling switch
therefor enclosed in an independent casing substantially integral with the first
named casing whereby any damaging arcing at the switch is prevented from
iniuring the instrument, substantially as described.
9. An electrical ensuring instrument having a fixed and a movable part
enclosed in and insulated from a metallic casing, in combination with a switching

page_text: chamber independent from the first named chamber and enclosing a switch for
the operative parts of the instrument, together with insulated conductors running
from said switch to the operative parts thereof, substantially as described.
10. An electrical measuring instrument having the operative parts thereof
enclosed in a casing, in combination with an independent casing or chamber
substantially integral with the first named casing or chamber and a switch en-
closed in said independent casing, together with insulated conductors running
therefrom to the operative parts of the instrument, substantially as described.
11. A switch for an electrometer consisting of two conducting switching con-
tact springs normally connected to each other and to the movable and stationary
parts thereof, in combination with electrodes or terminals adjacent to said
switching springs or contacts, together with means for separating the contacts
and bringing them into connection with the terminals, substantially as described.
12. A switch for an electrometer consisting of two conducting switching con-
tacts or springs resting normally against each other and connected to the opera-
tive parts of the instrument, in combination with terminals located in the path
of said contact springs and electrically connected with the binding posts of the
instrument, together with means for separating the contact springs and simulta-
neously placing them in contact with said terminals, substantially as described.
13. A switch for an electrometer consisting of contact springs resting normally
against each other and connected to the operative parts of the instrument with
their free ends located in the path of terminals connected to binding posts, in
combination with means for separating the springs, and additional means for
locking them in their separated positions, substantially as described.
14. An electrical measuring instrument provided with binding posts electrically
insulated from the enclosing casing in combination with a switch having yielding
contacts supported by the casing but insulated therefrom and electrically con-
nected to the operative parts of the instrument, said switch being provided with
means for separating the yielding contacts and placing them in contact with
the binding posts and means for locking them in the latter position, substantially
as described.
15. In an electrometer a hollow pivot shaft provided at its opposite ends with
pivot pins, in combination with an electrostatic armature or needle and an indi-
cating needle, together with means for securing said armature and needle to the
shaft, substantially as described.
16. In an electrometer a pivot shaft, in combination with an electrostatic
armature or needle and an indicating needle secured thereto, said parts being
composed of aluminium, substantially as described.
17. In an electrometer a hollow pivot shaft and an electrostatic armature or
needle and an indicating needle secured thereto, said parts being composed of
aluminium, in combination with pivot pins secured in the opposite ends of said
pivot shaft, substantially as described.
18. In an electrometer a hollow pivot shaft having secured thereto an electro-
static armature or needle and an indicating needle, the indicating needle being
electrically insulated from the shaft, substantially as described.
19. In an electrometer a hollow pivot shaft having secured thereto an electro-
static armature or needle and an indicating needle, the indicating needle being
electrically insulated from the shaft, in combination with pivot pins secured in
the opposite ends of the shaft, substantially as described.
20. An electrometer provided with a stationary electrostatic field and a disc-
like electrostatic armature or needle supported by a pivot shaft. in combination
with a conducting retractile spring connected to said shaft and to the stationary
part of the instrument, together with circuit connections running from the termi-
nals thereof to said parts, substantially as described.
21. An electrometer provided with a stationary electrostatic field and a mov-
able electrostatic armature or needle, in combination with an indicating needle
attached to or carried by the electrostatic armature or needle, a calibrated scale,

page_text: and an independent indicating needle having means for moving it by hand to any
predetermined point whereby comparative readings may be taken, substantially
as described.
22. An electrometer provided with a stationary electrostatic field and a mov-
able electrostatic armature or needle adapted to move in said field in combination
with an indicating needle attached to or carried by the electrostatic armature or
needle, a calibrated scale, and an independent indicating needle all enclosed in
a casing, the independent indicating needle being provided with means extending
through the casing for moving it by hand to any predetermined point, whereby
comparative readings may be taken at a distance, substantially as described.
Dated this 22nd day of March 1898.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.