An Improved Amperè Gauge and Connections.
Year: 1888

page_text: Date of Application, 11th Dec., 1888
Complete Specification Left, 7th Sept., 1889-Accepted, 30th Nov.. 1889
An Improved Amperè Gauge and Connections.
I, Sir WILLIAM THOMSON, Knight, of Glasgow College, Doctor of Laws and
Professor of Natural Philosophy in the University and College of Glasgow, in the
County of Lanark, North Britain do hereby declare the nature of this invention to be
as follows:-
For an inspectional ampere gauge the current to be measured is so dealt with in
a vertical solenoid, that it pulls in one direction, preferably upwards, a thin bar or
needle of soft iron hanging vertically from a spring or from one arm of a
counterpoised balance. The amount of the current is indicated by an index upon a
scale. This index is deflected through angles varying according to the extent to
which the needle is attracted into the solenoid. A solenoid of any known construction
may be used. The solenoid which I prefer is of special construction consisting of a
series of flat plates divided and bent at the centre, and united so as to form a
solenoid. A current through this solenoid produces a strong magnetic force in its
hollow interior field of which the transverse section is of small diameter and may be
of circular or elongated shape.
The improvements also include a spring clip for throwing any part of the apparatus
into or out of the circuit in which it is to be used without disturbing other apparatus
in the circuit.
The improved clip consists of an arrangement by which two conductors, both of
which may be elastic, preferably a number of clastic plates, or one clastic and one
rigid, meet at an angle which may be acute or obtuse or zero, and are pressed by
screw or otherwise elastically but firmly against each other. The constituent parts of
the elastic portion of the clip may be insulated from each other and connected through
resistances to a single conductor when it is desired to gradually introduce resistance
before breaking the circuit. The circuit is broken or extended by a plate-piece which
consists either of a flat-piece of slate or other insulating material, or of a couple of flat.
pieces of metal each connected to a flexible electrode but insulated from one another
by slate or other insulated material and firmly bolted together. The first mentionel
plate-piece is used to break the circuit, the second to extend the circuit by inserting
another circuit.
Dated this 10th day of December 1888
BOTTOMLEY & LIDDLE.
115, St. Vincent Street, Glasgow, Petitioner's Agents.
COMPLETE SPECIFICATION.
An Improved Ampère Gauge and Connections.
I, Sir WILLIAM THOMSON, Knight, of Glasgow College, Doctor of Laws and
Professor of Natural Philosophy, in the University and College of Glasgow, in the
County of Lanark, North Britain, 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:-
For an inspectional ampere gauge the current to be measured is so dealt with in a
vertical solenoid that it pulls in one direction, preferably upwards, a thin bar or needle
of soft iron hanging vertically from a spring or from one arm of a counterpoised
balance. The amount of the current is indicated by an index upon a scale. This
index is deflected through angles varying according to the extent to which the needle
is attracted into the solenoid: A solenoid of any construction may be used. The
solenoid which I prefer is of special construction consisting of a series of flat plates

page_text: divided at the centre and united so as to form a solenoid. A current through
this solenoid produces a strong magnetic force in its hollow interior field of which the
transverse section is of small diameter and may be of circular or elongated shape.
a
In order that my Invention may be properly understood and readily carried into
effect I have hereunto appended three explanatory sheets of drawings in the several
Figures of which corresponding parts are marked with the same letters of reference.
These
An ampere gauge constructed according to the principle hereinbefore described is
shewn in Figures 1, and 2; Figure 1 being a front elevation, and Figure 2, a
vertical section on the line a a bb, Figure 1: Figure 3, a plan of one of the plates
composing the solenoid; Figure 4, an edge view of one of these plates; and Figure 5,
plan of the damper hereinafter referred to. The solenoid consists of a number of
plates of copper; in the drawing eleven are shewn C, to C, each having a hole i, and
slot as shewn in Figures 3, and 4 dividing it at one end into two tongues d', e¹. The
end of each of the tongues d', e', is reduced in thickness for about half a
centimeter of its length, as shewn in Figure 4, in order to provide a means of making
a scarph joint with the connecting pieces f¹, hereinafter referred to.
tongues d, e, are then bent, the one up and the other as far down, until the scarphed
parts of each tongue are in planes separated by a distance equal to the thickness of the
plate e, together with the thickness of the insulating material placed between the
plates in the construction of the solenoid. The connecting pieces f, f², &c., are
simply oblong thin plates of copper or other suitable metal preferably of the same
breadth as the solenoid plates to c". To construct the solenoid these plates c¹,
to e, are placed one above the other, with plates of nica or other insulating material
between them when, in virtue of the relative displacement of the two tongues of each
plate, that is to say, one tongue being bent up and the other down, each pair of
tongues which are in the horizontal plane consists of one tongue from the lower, and
one tongue from the upper of each contiguous pair of plates. The eleven plates thus
built up are joined in series to constitute the solenoid in the following manner,
beginning with the uppermost plate c'. The tongue d', of the plato c', is metallically
connected by soldering or otherwise to the upper terminal plate g. The tongue d², of
the plate, and the tongue e¹, of the plate, being as hereinbefore described in the
same horizontal plane, are metallically connected at the scarph joints (Figures 3 and 4)
by soldering or otherwise to the right hand end of the connecting piece f¹. The
remaining plates of the series are similarly connected by the scarph joints of the
successive pairs of tongues d³ with e; with eto with ew being soldered or
otherwise secured to the right hand ends of the corresponding connecting pieces f³
to 10 The tongue e, of the lowermost plate el, is metallically connected by
soldering or otherwise to a terminal plate h. Thus the direction of the current
entering the solenoid by the terminal plate g, is d¹, c¹, e¹, f¹, d³, c², e², ƒ³,
to dc, el, to the terminal plate h. The connecting pieces f¹ to f1 also serve to
provide large radiating surfaces in order to minimise the elevation of temperature due
to the heat generated in the solenoid by the action of the current. The plates c¹ to cl
are so placed that the series of holes are in a vertical line, and so constitute a cylinder
or hollow core i, of small diameter in the centre of the solenoid.
When currents of several hundred amperes are to be measured and therefore plates
too thick to be conveniently bent in the manner above described are required, I form
the connections by placing the connecting plates 1, in inclined or diagonal positions
so as to connect the left hand tongue of one plate with right hand tongue of the
plate below; the ends of the tongues being diagonally grooved and the connecting
plates soldered into the grooves.
The soft iron rod j, upon which the solenoid acts is preferably of great length in
comparison with its diameter, in order to reduce to a minimum any error due to
the magnetic retentiveness of the iron. In the instrument represented in Figure 1,
the iron rod j, is 24 centimeters long, and 0.1 of a centimeter diameter. This rod j
is hung on a balance arm k, Figure I, by means of a transverse bar 1, Figures 1 and 2,
fixed to the rod j, as near as may be to the part of that bar which enters into
the solenoid, in order to diminish any inconvenient effect from the tendency of

page_text: the magnetised rod j, to jump to one side or other of the core i, in which it acts. A
weight m, suspended from a hook on the lower end of the rod j, balances for the
stronger currents the excess of magnetic attraction above the weight of the rod. The
counterpoise weight ¹, on the balance arm k, as well as the weight m, suspended on
the lower end of the rod j, can be unhooked and placed in receptacles p, and p', when
not in use or when the instrument is being moved from place to place. The balance
arm k, has rigidly fixed to it a long pointer n, whose end traverses the arc o, on which
the scale divisions are marked.
The instrument may be graduated for use either for measuring alternate or direct
currents, but in some cases it may be graduated so as to be available for both, and the
are o, may be provided with two scales, as shewn at Figure 1, one of which is
graduated to apply to the direct current and the other graduated for alternate currents.
These scales are to be graduated by comparison with one of my standard electric
balances. The graduation of the scale is such as to read amperes or multiples of
amperes per scale division. To check the vibrations of the pointer n, and so permit
of readings being quickly taken, a checker is provided. This checker consists of a
hinged bar shewn in plan in the detached view, Figure 5, carrying parallel to its
length a light springy arms, which may be brought into the plane of motion of the
pointer n, by means of the insulated handle y, when the friction between the springs,
and the pointer n, produces the required checking action. A spiral spring t, keeps the
hinged bar r, close to the back plate of the instrument when not in use, and permits
of it being momentarily pressed forward to bring the checking friction into action.
The pointer when the instrument is not in use, or when it is moved from place
to place, is prevented from moving about by the point being placed in a recess,
wherein it is securely confined by the button q, and easily released when required.
To the upper and lower part of the solenoid are attached the terminal clips U,
and U, which are of special construction, that is to say the parts U, and U¹, consist
of a block of copper or brass with a series of parallel flat narrow spaces therein
as shewn, and having a screwed stud w, fixed into the lower plate and passing up
through a series of spaces and plates. This screw carries a milled pinching nut w₁,
at the top. The terminals V, and V, of the conductors V2, and V³, consist also of a
series of flat plates whose thickness corresponds to the width of the spaces in the clips,
and whose spaces correspond to the thickness of the plates of the clips. The
terminals V and V1, have a slot a, Figure 6, cut in each plate equal in width to the
diameter of the stud w, so that the terminals can be easily slid into the clips, and when
there, are securely clamped by the pinching nuts w¹.
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:-
1. The general arrangement and construction of parts constituting the ampere gaugo
as hereinbefore described and shewn at Figures 1 to 6 of the annexed drawings.
2. The special construction of solenoid with or without extension of the connecting
pieces f, for the purpose of keeping the solenoid cool.
3. The supporting of the soft iron bar or needle by a shaft fixed transversely to it as
close as may be to the mouth of the solenoid into which it enters to prevent instability
due to lateral electro-magnetic force upon the part of the iron within the solenoid as
described.
4. The vibration checker, as described with reference to the ampere gauge.
5. In an ampere gauge the employment of two scales, one of which is graduated for
reading off by means of the pointer the strength of a continuous current, while the
other is graduated for reading the strength of alternate currents.
Dated this fith day of Santumbor 1900
BOTTOMLEY & LIDDLE,
154, St. Vincent Street, Glasgow, Applicant's Agents.

page_text: Date of Application, 11th Dec., 1888
Complete Specification Left, 7th Sept., 1889-Accepted, 7th Dec., 1889
PROVISIONAL SPECIFICATION.
Improved Apparatus for Continuously Measuring Potentials
or Currents.
I, Sir WILLIAM THOMSON, Knight, of Glasgow College, Doctor of Laws and
Professor of Natural Philosophy in the University and College of Glasgow, in the
County of Lanark, North Britain do hereby declare the nature of this invention to
be as follows:-
For measuring potentials or currents continuously from either side of zero in
either direction distinguishing between positive and negative currents, I use a
imagneto-static galvanometer similar to that described in the specification of the said
Sir William Thomson No. 9016 of 1886 with the following improvements:-.
(1). A vibration checker like that hereinbefore mentioned which may be also used
as a lifter to render the instrument portable.
(2). Support of the suspended magnet by a sapphire cup or cap and iridium point,
as in my graded galvanometer described in my Specification No. 5668 of 1881, with
a bracket carrying a light vertical shaft below the bearing point so as to retain the
general arrangement of the magneto-static galvanometer described in my above
mentioned Specification No. 9016 of 1886.
(3). An improved system of controlling magnets consisting of a steel magnet or
magnets preferably in the shape of horizontal rings according to which the directive
force on the needle may be varied in magnitude and direction and may be varied in
direction without changing the magnitude.
Dated this 10th day of Dovember 1888
BOTTOMLEY & LIDDLE,.
154, St. Vincent Street, Glasgow, Applicant's Agents.
COMPLETE SPECIFICATION.
Improved Apparatus for Continuously Measuring Potentials
or Currents.
I, Sir WILLIAM THOMSON, Knight, of Glasgow College, Doctor of Laws and
Professor of Natural Philosophy, in the University and College of Glasgow, in the
County of Lanark, North Britain 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 :-
For measuring potentials or currents continuously from either side of zero in
either direction, distinguishing between positive and negative currents, I use a
magneto static galvanometer similar to that described in my Specification No. 9016
of 1886, with the following improvements:-
-
(1) A vibration checker which may be also used as a lifter to render the instrument
portable.
(2) Support of the suspended magnet by a sapphire cup or cap and iridium point
as in my graded galvanometer described in my Specification No. 5668 of 1881 with
a bracket carrying a light vertical shaft below the bearing point so as to retain the
general arrangement of the. magneto static galvanometer described in my above
mentioned Specification No. 9016 of 1886.
(3) An improved system of controlling magnets consisting of a steel magnet or
magnets preferably in the shape of horizontal rings according to which the directive
force on the needle may be varied in magnitude and direction and may be varied in
direction without changing the magnitude.
In order that my Invention may be properly understood and readily carried into

page_text: :
effect, I have hereunto appended two explanatory sheets of drawings, in the several
Figures of which corresponding parts are marked with the same letters of reference.
Figure 1, is a vertical section through the centre at right angles to the plane of
the electro-magnetic coil.
Figure 2, is a plan of the instrument.
"L,
Figures 3 and 4, are separate drawings of the checker, Figure 3 being a vertical
section and Figure 4 a plan. Like letters of reference refer to like parts throughout.
The magnetic needle is suspended within a round guard tube at the centre of the
magnetic field, due to the two electro-magnetic coils b, b, by the bracket G and the
sapphire cap or cup d, resting upon the iridium point e. An indicator f, attached to
the cap d, shews the deflection of the magnetic needle on a scale g, graduated
according to tangents, so that differences of the numbers shown by the indicator on
this scale are in simple proportion to different strengths of current through the coils...
The terminals of the circuit of the coils are shown at h, h².
Surrounding the coil and magnet there is a cylindrical brass case i, upon which are
fitted two annular frames j, j¹, each capable of independent azimuthal motion, and
each having two pinching nuts k, k¹, kl, kl. Each of these frames carries a
controlling magnet 7, in the space provided for it. Each of these controlling magnets
is in the form of a ring of rectangular section, and is in two halves; the halves being
placed with like poles adjacent. The directive force of the magnet 1, on the needle a,
may be altered in magnitude by altering the relative azimuthal position of the poles
of the two controlling magnets, and may be altered in direction by turning both
frames with their magnets simultaneously in azimuth. The scale g, g, is adjustable in
azimuth so that when the magnets are set to bring the indicator to the middle of the
scale (marked 40) equal currents in opposite directions shall give equal deflections.
The position of the scale to fulfil these conditions must be found by trial, and when
this position is found the scale is clamped by means of a clamping screw provided
for the purpose. In ordinary use of the instrument the magnets are set to cause the
indicator to stand at some such position as 0, 10, or 20, of the scale as shewn in
Figure 2.
For checking the vibrations of the indicator, I use a rigid, or elastic piece of solid
material which may be brought momentarily and, gently to touch upon the indicator
itself or other connected moving part of the apparatus. To prevent all other motion
of the checker than the one desired, I mount it in such a manner that the moving part
of the checker is guided on five bearing points so arranged that the only motion
allowable is in the required straight line.
The moveable piece of solid material consists of a ring m, Figures 2, 3, 4 of brass,
or other suitable material having its centre in the axis about which the indicator f,
turns, and supported in a horizontal plane beneath the plane of motion of the indicatorf,
by means of a slide constructed as follows:-
A round vertical guide rod n, in Figures 1, 3 and 4 to which the ring m, is
attached passes through V-shaped. openings o, o, in the bracket p. Thus in virtue of
gravity acting on the whole moving body m n, Figures 3 and 4, with or without the
addition of a spring 9, pulling the vertical stem downwards the guide-rod is pressed
into the upper and lower V-shaped openings o, o. A small pin r, Figure 2, is fixed
in the plate touching the circumference of the ring m, which is kept pressed against
the pin, by a small spiral spring s. The five bearing points of the moving body
are two in each of the V-shaped openings o, and one at the pin . Thus the only
motion possible to the moveable body m n, is in a strictly vertical direction up or
down, and this motion is given when required by means of a cam t, acting on a
projecting plate w, and rotated by means of a handle v.
The mechanism now last described with reference to Figures 3 and 4 as a vibration
checker for the indicator f, may be also by obvious arrangements used as a means of
rendering the instrument to which it is applied readily portable. Thus it may be
made to lift the whole inoveable body off the point of support and to clamp it
securely against a fixed support. A spirit level x, Figure 2, is provided to shew:
when the instrument is level.

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, I declare that what I
claim is :-
1. The arrangement and construction of parts constituting the magneto static current
meter.
2. In the magneto-static current meter the construction of the magnetic needle,
vertical sten, and bracket, indicator needle, and cap, supported on a point by which
the magnetic needle is supported under the bearing point with or without a
surrounding guard tube for the purpose of portability, substantially as herein before
described and shewn on the annexed drawings.
3. In the magneto static current meter, the vibration checker also its use as a
lifter for portability, substantially as hereinbefore described and shewn upon the
annexed drawings.
4. In the magneto static current meter the special arrangement of controlling
magnets according to which the amount of the controlling force is adjusted by moving
the one magnet relatively to the other, and also the zero is adjusted by turning
the two magnets, substantially as hereinbefore described and shewn on the annexed
drawings.
Dated this 6th day of September 1889.
BOTTOMLEY & LIDDLE,
154, St. Vincent Street, Glasgow, Applicant's Agents.

page_text: Date of Application, 11th Dec., 1888
Complete Specification Left, 7th Sept., 1889-Accepted, 30th Nov., 1889
PROVISIONAL SPECIFICATION.
Electro-static Apparatus for Measuring Potentials.
I, Sir WILLIAM THOMSON, Knight, of Glasgow College, Doctor of Laws and
Professor of Natural Philosophy, in the University and College of Glasgow, in the
County of Lanark, North Britain do hereby declare the nature of this invention to be
as follows:-
For measuring high potentials, I use an electrostatic arrangement of which the part
whose potential differs most from the earth is a smooth insulated conductor, which may
be of a cellular or multicellular form. The moveable body may be a metal plate or
an arm or a group of metal plates or vanes. The electrostatic force acting upon the
moveable body may be equilibrated by torsion or by torsion and gravity as in the
well-known bifilar balance; or by gravity as in an ordinary balance; and may be
read by inspection on a scale, or may be determined by a balancing operation.
For checking the vibrations of the index, I use a rigid or elastic piece of solid
material which may be brought momentarily and gently to touch upon the index itself
or other connected moving part of the apparatus. To prevent all other motion of the
checker than the one desired motion, I mount it on a geometrical slide (see Thomson's
and Tait's Treatise on Natural Philosophy 2nd Edition vol. I, part I, § 198).
Dated this 10th day of December 1888.
ST. JOHN V. DAY,
115, St. Vincent Street, Glasgow, Applicant's Agent.
COMPLETE SPECIFICATION.
Electro-static Apparatus for Measuring Potentials.
I, Sir WILLIAM THOMSON, Knight, of Glasgow College, Doctor of Laws and
Professor of Natural Philosophy in the University and College of Glasgow, in the
County of Lanark, North Britain, 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 :-
For measuring high potentials I use an electro-static arrangement of which the
part whose potential differs most from the earth is a smooth insulated conductor,
which may be a cellular or multicellular form. The moveable body may be a metal
plate or an arm or a group of metal plates or vanes. The electro-static force
acting upon the moveable body may be equilibrated by torsion, or by torsion and
gravity, as in the well-known bifilar balance, or by gravity as in an ordinary
balance; and may be read by inspection on a scale, or may be determined by a
balancing operation.
For checking the vibrations of the index, I use a rigid or elastic piece of solid material,
which may be brought momentarily and gently to touch upon the index itself or
other connected moving part of the apparatus. To prevent all other motion of the
checker than the one desired motion, I mount it on a geometrical slide.
In order that my Invention may be properly understood and readily carried into
effect, I have hereunto appended three explanatory sheets of drawings in the several
Figures of which corresponding parts are marked with the same letters of reference.
These relate to the particular plan in which the vanes move in horizontal planes
round a vertical axis and are supported by a single fine metallic wire, but the
arrangement may be varied obviously to bifilar suspension or to support on knife
edges giving motion to the vanes in a vertical plane round a horizontal axis. In

page_text: which case the electric force may be most conveniently balanced by a counterpoise
attached to the indicator pointer.
Figure 1, is a vertical section of the instrument with the interior parts in elevation
constituting my electro static volt meter, and Figure 2 is a plan of the same.
Figure 3, is a plan of part of the underside of the plate b, Figure 1, shewing the
insulated body and the repulsion plates.
Figures 4 and 5, are an elevation and plan respectively of the vertical shaft of
the instrument and the thin plates or vanes g¹, to go.
Figures 6 and 7 are details of the checking device or "checker," as I prefer to.
call it, and hereinafter more particularly referred to. The fixed insulated body is
divided into two parts which are metalically connected by means of the metal
wire d', and placed relatively to each other as indicated at d, d, in Figures 1
and 3, being attached by means of insulating supports (shewn at a, in Figure 1)
to the brass plate b, which forms part of the enclosing case of the instrument.
Each of these two parts of the fixed insulated body consists of a number of plates
shaped as shewn at d, in Figure 3, and so connected together as to form a number of
superimposed spaces or cells c, of which the vertical dimension is shewn at c, in
Figure 1, while the horizontal dimensions are shewn at d, in Figure 3.
The moveable body of the instrument consists of a spindle e, suspended vertically
between the two parts of the fixed insulated body by means of a torsion wire f, and
carrying a number (five as shewn in the drawing, Figure 1) of light metallic vanes g,.
to go, Figures 1, 4 and 5, placed with their surfaces horizontal, that is to say at right
angles to the spindle and at the same distance apart as the plates d, d, forming the
two parts of the fixed insulated body. This movable body is supported in such a
position relatively to the spaces c, c, of the fixed insulated body, that when the
spindle e, rotates about its axis, each of the vanes g¹, to go, moves in a horizontal
plane situated midway between the plates d, d, constituting the pair of corresponding
spaces c, c. The instrument is provided with two repelling plates whose function is
hereinafter more particularly referred to in describing the action of the instrument.
These repelling plates consist of two vertical brass plates h, Figures 1 and 3, fixed to
the brass cover, of the containing case i, in the position shewn at 1, in Figure 3.
The index j, is fixed to the top of the spindle e, and its point traverses a circular scale k,
Figure 2 graduated to any required multiple or submultiple of volt per division.
The covering plate b, forming the top of the case i, containing the insulated body
serves to screen the index j, from inductive electric influence and the box 1, with glass
cover m, prevents disturbance from currents of air. The moveable body with pointer
is supported by a wire f, which is guarded by a brass tube n, carried by the bridge o,
and having at its top any convenient attachment for securing and providing an
azimuthal adjustment for the upper end of the wire f. A spring f1, is provided between
the index, and the wire f, for the purpose of guarding the wire from shocks which
might injure it.
To prevent damage to the insulated moveable body when the instrument is being
· carried about, I fix to the lower end of the spindle e, a pin p, passing through a hole
(wide enough not to touch the pin p, when the instrument is in use) in the plate q,
carried by the two repelling plates h, and which has on its lower end an enlargement
or head. A screw r, in the sole plate vertically beneath the pin p, may be screwed up
so as to press the head of the pin p, against the guide-plate q. By this means the
lower end of the moveable body becomes fixed, and the weight on the torsion wire
being relieved, it also is protected from liability to strain when the instrument is
carried about.
For checking the vibrations of the index I use a rigid or elastic piece of solid
material which may be brought momentarily and gently to touch upon the index
itself or other connected moving part of the apparatus. To prevent all other motion
of the checker than the one desired motion I mount it on a geometrical slide, that is
to say the moving part of the checker moves upon five bearing points so disposed that
the only motion possible is in the required straight line.

page_text: The vibration checker is shewn in Figures 1 and 2, and for greater clearness
of illustration separate drawings of the checker are given in Figures 6 and 7,
Figure 6, being an elevation, Figure 7, a plan. The designating letters in
Figures 1, 2, 6 and 7, as applicable to parts of the checker are identical. The
moveable piece of solid material consists of a ring s, of brass or other suitable
material having its centre in the axis about which the index j, turns, and supported
in a horizontal plane beneath the plane of motion of the index j, by means of a
geometrical slide constructed as follows:-A round vertical guide-rod t, to which the
rings, is attached passes through V-shaped openings u, u, one in the bracket w, and
the other in the covering plate b. Thus in virtue of gravity acting on the whole
moveable body st, Figures 6 and 7 the guide-rod t, is pressed into the upper and
lower of the V-shaped openings u, and u. A small pin a, is fixed in the plate b, as
shewn in Figure 2, touching the circumference of the rings, which is kept pressed
against this pin a, by a small spiral spring y. The five bearing points of the checker
are two in each of the V's u, and one at the pin x. Thus the only inotion possible to
the moveable body st is in a strictly vertical direction up or down and this motion is
given when required by means of a cam z, acting upon a projecting plate a¹, and.
rotated by means of the insulated handle b¹.
The mechanism now last described with reference to Figures 1, 2, 6 and 7, as a
vibration checker for the index j, may be also by obvious arrangements used as means
of rendering the instrument to which it is applied readily portable. Thus it may be
made to lift the whole moveable body and to clamp it firmly against a fixed support,
and so protect the torsion wire or other bearings as the case may be from damage
when the instrument is being carried about. The instrument is supported on three
insulated feet.
The graduation of the scale of the electro-static volt meter may be performed by
comparison, division for division, with standard instruments.
The action of the electro static volt meter which has now been fully described with
reference to the annexed drawings is as follows:-of the two points in an electric
circuit whose difference of potentials is to be measured, that one whose potential differs
most from the earth is connected by a suitable electrode to the terminal c', connected
metallically with the insulated body d d, while the other point is connected to a
terminal, on the brass case i, of the instrument. From the difference of potentials
thus produced between the cells cc, and the adjacent parts of the corresponding
vanes gl, to g³, there arises an attractive force between these bodies which causes the
spindle e, carrying the vanes g', to 9, and the index j, to turn in azimuth. A con-
tribution to the turning force is also produced in the spindle e, with its attachments,
by the repelling force between the two plates h, h, and the adjacent portions of the
vanes g, io g. The turning movement on the spindle e, and its attachınents of these
attractive and repelling forces for any stated difference of potential is balanced by the
torsion of the bearing wire f, in the azimuthal motion so produced, and in the
inspectional use of the instrument which is that shewn in the annexed drawings,
the index j, will point to that division of the scale k, which indicates the required
difference of potential.
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 :-
1. The general arrangement and combination of parts constituting the electro-static
apparatus for measuring potentials, operating as hereinbefore described and shewn at
Figures 1, 2, 3, 4 and 5 of the annexed drawings.
2. In the instrument herein before described, a series of flat metallic vanes fixed
perpendicularly to one shaft and actuated by electric forces due to fixed plates between
the ends of the consecutive vanes in the series as shown on the annexed drawings.
3. The arrangement by which the motion of these vanes due to the electric
forces is shewn by an index needle fixed perpendicularly to the shaft and turning in

page_text: a space screened from electric force by a metal plate with a small central hole
through which the shaft passes, as hereinbefore described and shewn on the annexed
drawings.
4. In the electro-static instrument the vibration checker as described and shown
with reference to the annexed drawings Figures 6 and 7.
Dated this 6th day of September 1889.
BOTTOMLEY & LIDDLE,
154, St. Vincent Street, Glasgow, Applicant's Agents.