IMPROVEMENTS IN APPARATUS AND PROCESSES FOR GENERATINGULATING AND MEASURING ELECTRIC CURRENTS
Year: 1883

page_text: LETTERS PATENT to 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 for an
Invention of "IMPROVEMENTS IN APPARATUS AND PROCESSES FOR GENERATING,
ANAS
PROVISIONAL SPECIFICATION left by the said Sir William Thomson at the
Office of the Commissioners of Patents on the 21st April 1883.
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 "IMPROVEMENTS IN APPARATUS AND PROCESSES
FOR GENERATING, REGULATING AND MEASURING ELECTRIC CURRENTS,"
This Invention relates to improvements in apparatus and processes for generating
regulating and measuring electric currents.
In generating electric currents according to this invention I use a wheel con-
sisting of spokes of copper of which the outer ends are metallically connected by a
copper rim and the inner ends are held securely by discs or clamps, constituting as
it were the boss of the wheel and strong enough to balance the centrifugal force
irrespectively of the rim; although a part of the centrifugal force of the spokes
may be borne by the rim.-The spokes are insulated from each other, and from the
metal portions of the discs or clamps by which their inner ends are held.―The
electric current is supplied through brushes touching the spokes themselves,
towards their inner ends, or collector-bars connected with the inner ends of the
spokes, and placed on a cylinder like the commutator bars of ordinary dynamos.―
The current is induced by the motion of the spokes across the lines of force of
permanent magnets or electro-magnets, so placed as to give fields of force with
lines approximately perpendicular to the plane in which the spokes of the wheel
move. Brushes of some of the ordinary patterns may be used, but in some cases,
I prefer brushes resembling camel hair brushes, each being of very fine wire.-The

page_text: bundle, preferably of rectangular section, is cut obliquely, so that the free ends may
lie approximately in a plane making an angle for example of about 45°, with the
length of the brush.-The brushes are all mounted in a copper sheath, each in a
separate tubular compartment.-Each brush is pressed longitudinally on its solid
end where the wires are consolidated by solder, so as to give rise to the proper
amount of pressure of the soft end on the collector bars.-This pressure is produced
by a weight of lead or other substance sliding in the sheath, or by a small spiral
spring, adjusted by a long screw working in a nut attached to the sheath. The
soft ends of the brushes project a short distance beyond the sheath which is cut at
the proper angle, 45° for example, to the direction of the tubular guides.---The
sheath may be so set that the length of each tubular guide lies in any position,
inclined at the supposed angle of 45°, to the tangent plane. When it is desired to
allow the wheel to rotate in either direction without injuring the brushes, the
direction of each tubular guide ought to be in a plane through the axis of the
wheel.
In order to minimise the resistance to the independent motion of each brush in
its guide, the currents from the several brushes are collected by sufficiently flexible
wire ropes soldered one to each brush.-These wire ropes may be brought together
in the two main terminals of the circuit; or they may be separated in lots and
applied to separate pairs of terminals each pair being in an independent circuit.
When the dynamo is driven by a belt I support its framework by means of
wheels or rocking curves.-These wheels or curves rest on inclined planes or on
inclined bearing surfaces such as the inclined faces of wedges resting with their
other faces on a horizontal floor; or when it is not convenient to use inclined
planes, the belt may be tightened by a horizontal force applied by a spring or by
a rope passing over a pulley and stretched by a weight.--In some cases I hang the
dynamo by rods or chains from above, with guides to prevent it from having more
than one degree of freedom to move; and use the movement of its own weight or
of a rope passing over a pulley and stretched by a weight to keep the belt
sufficiently tight.
To regulate the potential produced by the dynamo I use a rapidly rotating
vessel partially filled with oil.-The rotation causes the oil to rest with its free
surface approximately a vertical cylinder.—A pair of toothed wheels gearing into
one another with their axes nearly vertical, and mounted on a moveable frame so
that when the frame-work is moved to one side or the other, one wheel or the
other is caught and caused to turn rapidly by the oil, produces, by this turning
motion, the change, whether of the speed of the engine, or of the resistance in the
circuit of the electro-magnet of the dynamo, or of whatever arrangement in the
apparatus is requisite to adjust the potential produced by the dynamo to the desired
amount. The turning motion of one of the pair of wheels is communicated to a
shaft on fixed bearings by means of a crown wheel and pinion or otherwise in such
a manner as not to inconveniently hamper the motion of the moveable fram-
work. One way of effecting this is to mount the moveable frame-work on pivots
having a horizontal axis passing through the point of contact of the pinion and
crown wheel. Auother way which in some cases I prefer, is by means of a grooved
drum carried by one of the two shafts, and a cord carried once round this drum
and stretched from it in opposite directions approximately horizontal and perpen-
dicular to the plane of motion of the moveable framework.-This cord may be
endless and stretched in the manner described, by a tightening pulley on one side
and a pulley supported on a fixed axis on the other side.-The motion of this last
mentioned pulley produces, generally by a speed-reducing train, the requisite
adjusting action.
The same arrangement may also be used when current, instead of potential, is to
be regulated. It may be also used as a power-relay in any case in which it is
desired to cause a large adjusting force to act in one direction or the other under
the control of a comparatively delicate motion with small moving force.—When
electric potential or current is to be regulated the controlling force is the difference

page_text: between an electric or electro-magnetic force due to the actual potential or current
at any instant and its value when the potential or current is at exactly the right
degree; and acts in one direction or the opposite according as the difference is
positive or negative.-The electric or electro-magnetic force referred to may be
produced in a great variety of ways by known methods whether the potential or
current, to be regulated, be that of a constant current, or be the mean potential or
current of a system of alternating currents.
When the potential to be regulated is that of an installation of electric lighting
by incandescent lamps, and when a large number of lamps are to be simultane >usly
extinguished, the rise of potential due to a sudden simultaneous extinction might,
before the regulator has time to bring the potential back to the proper amount, be
so great as to injure or destroy other lamps-In such cases I use an appliance by
which the extinction is effected by automatic gradual insertions of resistances,
lengthening the time of the extinguishing to five or six seconds, or whatever may
be necessary according to the speediness of the regulator, to allow the potential
to be regulated, so as not to rise injuriously during the extinguishing.-One mode
of effecting this, which I find convenient, is by a roller, containing a hollow with
radial partitions partially filled with mercury flowing slowly through small
apertures between the partitions when the roller rolls down an inclined plane.—
The rim of the roller which may be of brass or of copper or of iron gilt, makes
contact between a continuous metal surface on one side and a set of studs with
surfaces nearly in one plane on the other side; these two planes forming the
inclined sides of an inclined groove or channel down which the roller rolls when it
is extinguishing the lights.-When the roller approaches the lower end of its range
it rolls off the lowest stud and on to a non-conductor and thus breaks the circuit.-
When it is at the top of its range it makes contact for the lamps with as little
resistance as possible, and as it rolls down throws in more and more resistance by
resistance wires connected with the studs.
For a current integrator or coulomb meter I use a one-wheel carriage, wheel-
barrow, as I shall call it for brevity, on a horizontal disc, which is kept rotating
uniformly. The wheel of the barrow has a curved rim, broad enough and with
large enough radius of curvature to support the wheel-barrow stably, when the
crown of the cup described below as attached to the barrow, is supported on a
radial point in a prolongation of the bearing plane.-The weights of the barrow
are so arranged (like those of a common haud wheel-barrow), that if left to itself
on a horizontal plane, one end of it would rest on the plane.-This end is supported
by means of a fine point and cup, (like the point and cup of an ordinary magnetic
compass). Supposing the cup to be fixed, mouth down, to the barrow, the point is
supported on an arm attached to or connected with, the moveable body of an
electro-magnetic arrangement (a powerful enough galvanometer,) giving it
horizontal motion in one direction and the opposite when the current increases
and diminishes.-The displacement of the bearing point from its zero position
ought to be as nearly as possible in simple proportion to the strength of the
current, and as nearly as may be in a horizontal straight line, in a prolongation of
the plane of the rotating disc.-The crown of the cup attached to the barrow ought
to have, as nearly as possible, the same distance from the point, in which a tangent
plane through it to the rim of the wheel meets the rim, that the line of motion of
the bearing point has from the centre of the disc.-If this last condition could be
rigorously fulfilled, the zero position of the bearing point might be exactly at the
point in its line of motion nearest to the centre of the disc. With these adjust-
ments all rigorously carried out the angle turned through by the wheel in any ti ne
would be rigorously proportional to the desired time-integral of the current, if the
variation in strength of the current were infinitely slow. The direction of rotation
of the disc must be such, that its motion is from the bearing point, when displaced
from zero by the current to be measured.-When the bearing point is displaced
from its zero, the motion of the disc draws the barrow into the proper place for
integrating the current, and the pull of the barrow produces no disturbance of the

page_text: position to which the electro-magnetic force tends to bring the bearing point.—In
practice I generally adjust the zero of the bearing point to a little away from the
position of its line of motion nearest the centre of the disc. Thus when the
current to be measured is zero, the wheel of the barrow is kept turning at a slow
constant rate, as long as the disc is kept rotating.-The wheel-work by which the
disc is turned, is decimally arranged and graduated, so that the whole amount of
motion in any time may be read off.-A very light train of wheels geared to the
wheel of the barrow, and mounted on the barrow itself, serves to read off the
whole angle turned through by the wheel-These two counters are so arranged
and numbered, and the zero of the electro-magnetically moved bearing point is so
adjusted that the readings on the two counters grow equally, as long as the current
to be measured is zero.
The integral of the current in any time, is the excess of the increase of the
reading of the barrow-wheel counter, above the increase of the reading of the disc
counter. The sensibility of the electro-magnetic controller, is adjusted so that
the number thus given by the difference of the readings of the two counters, is the
number of coulombs, or of other chosen unit expressing the whole quantity of
electricity that has passed through the instrument in the time.
The electro-magnetic controller may be adapted to stop the wheel-work
whenever the current becomes less than the smallest that the user
can take
advantage of, as for instance that of a single lamp, or of the smallest lamp of an
installation of incandescent lighting.
To secure that no current shall pass unmeasured a make-break appliance is
introduced into the main circuit by which when the weight which drives the
wheel-work runs down to near the end of its range, the circuit is broken and can
only be remade by winding up the weight. The whole apparatus of counter
wheel-work, and this make-break adaption, are to be kept under lock and key, or
otherwise secured against intentional or unintentional mal-adjustment.
As an alternative method I use a gyrostatic system as follows.-a framework
moveable round a fixed shaft carries a second framework jointed to it so as to be
moveable relatively to it round an axis perpendicular to its axis.-The second
framework bears pivoted upon it a fly wheel and for brevity I shall call it and its
fly wheel, the gyrostat.-The axis of the fly wheel is perpendicular to the axis of
the first mentioned shaft.-The axis of the fly wheel bears a pinion worked by a
crown wheel co-axial with the first mentioned shaft. The framework carrying the
gyrostat is caused to rotate uniformly at a speed accurately regulated by a frictional
or other governor.-The line of the axis round which the framework carrying the
fly wheel can turn should pass through the point of contact between the teeth of
the pinion and of the crown wheel. When the crown wheel rotates at the same
speed the fly wheel gets no rotation.-The crown wheel is caused to rotate faster
than the bearings of the gyrostat, the difference of speed being regulated so as to
be in simple proportion to the controlling electro-magnetic force. This is effected
by means of a tilting motion of the gyrostat under the influence of the controlling
electro-magnetic force which is applied to act on a point of the gyrostat as nearly
as may be in a prolongation of the axis of the first mentioned shaft.
When the controlling force is just overbalanced by the tilting tendency of the
gyrostat a point of the gyrostat is caused by the tilting motion to press on a fixed
plane or rim and so to produce friction enough to stop further augmentation of
speed. A spring between the gyrostat and the frame-work on which it is pivoted,
is adjusted to control the tilting motion when gravity and centrifugal force are not
conveniently or sufficiently available.-A counter which counts the number of turns
of the fly wheel gives a reading in simple proportion to the quantity of electricity
which has passed in any time. The same instrument may be used merely as a
speed indicator for observing the speed, at any instant, of the dynamo or of any
rotating shaft. For this purpose the tilting of the gyrostat through a small angle
of about 10° for example measures the speed of the crown wheel relatively to the
gyrostat frame; a lever pressing lightly on a point of the gyrostat in the

page_text: prolongation of the axis of the first mentioned shaft serves to multiply the
tilting motion, and to shew the desired speed on a convenient fixed scale with
divisions, which are approximately equidistant to indicate equal differences of
speed.
"
As another alternative method, which has also the advantage of being applicable
to integrate the average of the current proceeding from an alternate current dynamo,
I use a piece of wheel-work arranged to move with a speed proportional to the
square root of a force applied to one point of it, which for brevity I shall call the
controlling force."-This I effect by means of a centrifugal governor, partially
constituted of mechanism analogous to Watt's original governor.-The controlling
force is applied to a point of the lever carrying the fork, or equivalent, through
which the influence of the jointed quadrilateral frame is transmitted.-This force
is so applied, as to counteract the centrifugal force of the governing balls or
masses.- -When it is underbalanced by the centrifugal force, the governing masses
are held in by, it and press against a ring which kept rapidly rotating, and which,
by their friction upon it augments their speed, until centrifugal force suffices to
annul their pressures on the moveable ring.-They then fly out slightly, and press
against a fixed concentric ring, surrounding the space in which they move; and
their friction against this ring prevents any further augmentation of their speed,
such as friction in the mechanism might cause them to take, from the rotating shaft
which carries the moveable ring.—When the mechanism is such as to give rise to no
such frictional force, the fixed ring may be omitted.-In the form of mechanism
which I at present prefer, there is such a frictional force, and it increases in amount
with increase of the controlling force, this being arranged for, in order that, with
the greatest controlling force to be provided for, the friction of the governing
masses on the moveable ring, may suffice to give them their lifting velocity-In this
particular plan of mechanism, I therefore use the fixed ring. Instead of a fork
and sliding tube on a continuous spindle as in Watt's governor, I prefer to have the
spindle in two parts telescoped together, and so connected by the jointed quadri-
lateral, that when the governing masses fly out, the length between the ends sball
be augmented. This allows to be used instead of a fork, a mere moveable end
plate, pressing on one end of the telescope shaft; which gives rise to much less
friction than the fork.-This end plate may be attached to one end of a lever,
which turns through only an exceedingly small angle during the action of the
apparatus; the amount of motion of the end plate itself, required for the governing
action, being exceedingly small. Thus a small controlling force, with a moderate
range of motion, may be applied to give, by leverage, a much greater force on the
end plate through its very small range.
The controlling force is to be produced by the mutual action between a fixed and
moveable portion of the conductor, through which the electricity to be measured
passes. The velocity, at which the governing balls are kept turning, is proportional
to the square root of this force; or of its average value when it alternates with
great rapidity, between zero and maximum, as it does in alternate current dynamos;
and a train of wheels driven by a pinion or worm carried by the governing masses,
allows the time-integral of the square root of the force, to be read off at any time.-
This integral is the proper measure of the value of the electricity supplied during
any time; whether from a continuous current or from an alternate current
dynamo.
As another alternative method, which has the advantage of avoiding the expense
and wear and tear of wheel-work, I use a stream of water, arranged to give into
a measuring vessel, a quantity of water simply proportional to the quantity of
electricity to be measured.-For this purpose I produce a fluid pressure varying in
simple proportion to the controlling force, and direct the pressure to cause water
to flow into the measuring vessel, at a rate proportional to the controlling force
simply, or to its square root, according as the electro-magnetic appliance is arranged
to give force proportional to the current, or to its square.-In the one case the
pressure forces the water at a slow rate through a capillary tube; in the other case,

page_text: it forces it through a wide tube ending in a fine nozzle.-In the former case, the
water must be kept as nearly as may be at one temperature; because the viscosity
of water is greatly influenced by its temperature, being greater at low temperatures,
and less at high temperatures.—To effect this, I use a metallic thermometer making.
or breaking circuit through a wire of large resistance connecting the two electric
mains, and wound round the space occupied by the capillary tube, and a portion of
a wider tube through which the water enters it.-The metallic thermometer breaks
or makes circuit whenever the temperature is above or below the proper degree.-
In the former case, I prefer to produce the required fluid pressure, by causing a
little cistern flexibly connected with the discharging end of the capillary tube, to
be lifted or lowered by the electro-magnetic controller.-In the latter case I use a
long wide vertical tube for example of one metre length and with a fine nozzle at
its lower end, hung on a balance.-This tube is lifted very slightly when the
weight of the water within it is too small, and is let down when the weight is too
great, by means of an electro-magnetic force produced by a fixed part of the circuit
acting on a moveable part attached to the balance.-The tilting of the balance thus
produced in one direction or the other, acts by means of an arm or connecting rod
on a feeding nozzle pushing it to one side or the other, so that water from it flows
into the open end of the vertical tube, or into a waste water drain beside it,
according as the electro-magnetic force is underbalanced or over-balanced by the
weight of the water in the vertical tube.
To produce the controlling electro-magnetic force for a regulator or a current
integrator, by means of the mutual action of fixed and moveable portions of the
electric circuit, I use for the moveable portions, two coils in parallel planes, with
the current going through them in opposite directions; in order that the balance
may not be disturbed by terrestrial magnetic force or by the magnetic force of
moderately distant dynamo machines, or other fixed or moveable magnets in the
neighbourhood.-For the fixed portion of the circuit to act on the moveable
portions, I use a flat coil fixed between the two moveable coils, so proportioned
that the distances from the outer and inner boundaries of the fixed coil, to the
nearest parts of the mean circles of the moveable coils, are considerable, in com-
parison with the distance between the fixed coils.-The moveable coil is so mounted,
as to have just one degree of freedom to move which should be, as nearly as can
conveniently be arranged for, perpendicular to the planes of the three coils.-This
may be done by knife-edge supports as in an ordinary balance, or by bifilar
suspension. For bifilar suspension I use the torsional elasticity of each of two
bearing. wires, by means of two torsion heads, each acting as the single torsion
head in coulombs unifilar torsion balance and adding their torques to bring the
moveable body to equilibrium in any marked position.-I use this method of a
.double torsion balance also in an Instrument otherwise agreeing with Weber's
electro-dynamo-meter, which I employ for adjusting and testing the sensibility
of the electro-magnetic appliances, by which I produce the controlling force in
the regulator, or for adjusting or finding the constants of the potential and
current meters.
To produce a controlling electro-magnetic force by mutual action between a
portion of the circuit and fixed magnets I use a moveable ring constituting part of
the circuit and two circles of opposite. magnetic poles outside and inside the ring,
so that the motion of the ring may be approximately perpendicular to lines of
magnetic force approximately along radii of a cylinder.-These magnetic poles may
be made of straight bar magnets all parallel to one another, and the other ends
may be magnetically connected by a soft iron ring between them; or the magnets
may be horse-shoes fixed so as to have their poles in the two circles.
For a potential meter to measure the difference of potentials between the main
conductors of the dynamo, or between any two points of its circuit, I use a coil of
fine insulated German silver wire wound on a bobbin of brass or other suitable
material; so mounted as to be capable of being turned slightly round a vertical
axis, through the point or fibre bearing the needle or system of needles, while the

page_text: graduated scale remains fixed; in order that the magnetic axis of the coil may be
adjusted into exact coincidence with the plane through the vertical round which
the needle or system of needles turns, and their magnetic axis.-This adjustment is
performed by trial; the test being that the deflections produced by equal currents'
in opposite directions shall be equal on the two sides of the position in which the
needle or system of needles rests when there is no current. For supporting the
needle or system of needles, I prefer a single silk fibre suspension, except when the
usage is likely to be such as to endanger breaking the fibre.-To render the instrument
portable with the silk fibre suspension, I use a special cradle controlled by a screw
for lifting the system of needles, and pressing it firmly against a roof, so as to take
the weight off the fibre.-The upper end of the fibre is attached to a brass tube,
which also carries the lifting mechanism, and which can be slipped into its proper
position in the galvanometer bobbin, or removed from it at pleasure. Thus if by
accident the silk fibre suspension is broken, a fresh tube with cradle and suspended
needle, can be instantly supplied to the instrument if the spare appliance is at
hand; or, in case of need can be sent by post or otherwise, to a distant station
without danger of breaking.
To adjust the potential meter conveniently to round numbers of volts, I use in
connection with it a special arrangement of resistance coils, which if made
sufficiently extensive, suffices also to adjust the instrument to measure potentials
through very wide ranges, as for instance of from one volt to 2000 volts. A single
standard voltaic cell, or a few such cells in series, or any convenient form of electro-
dynamo-meter, may be used for the primary adjusting and testing of the
galvanometer, with a controlling steel magnet as described in the Specification
filed in pursuance of my Patent N° 5668 A.D. 1881.-I insert, in series with the
galvanometer coil, an amount of resistance found by trial, so as to produce an
exact number of divisions of deflection, with a difference of potentials known
accurately in volts, which will generally be, not an integral number but, a numeric
with several places of decimals.-Then by a simple calculation, I find the resistance
which must be added to the galvanometer coil, to give an exact number of divisions of
deflection, for an integral number of volts.-When the instrument is to be used to
measure a much larger number of volts than the scale would admit of with the same
resistance, I throw in additional resistance so calculated as still to give an integral
number of divisions of deflection, for an integral number of volts. To allow these
operations to be performed conveniently and rapidly, I use a new decimal arrange-
ment of resistance coils, consisting of one or more pairs of tens of resistance coils.-
The twenty coils of each pair of ten are permanently soldered together in series.―The
junctions and the separate ends of the first and last coils, are connected by twenty-
one short wires to twenty-one studs fixed on a circle, or on two adjacent circles.-The
working terminals of the pair of tens, are connected with two arms turning round
an axis or axes, so that one of them may be brought from the centre stud to any
number on one side of it, and the other to any number on the other side of it.-The
ten coils on each side are of equal resistances, and the resistance, of each of those on
the left side, is ten times that of each on the right. The studs are numbered
from 0 to 10, on each side from the middle side.-Thus, for example, if the arm on
the left is placed at 7, and the arm on the right at 3, the resistance between the
two terminals is 73, times the resistance of one of the coils on the right.
Two such sets of decimal pairs placed in series, with the right hand working
terminal of one pair connected with the left band working terminal of the other
pair, gives a ready means of making up a resistance of from 1, to 11,110.-For
this purpose the resistance of each of the right hand coils of the left hand pair,
should be exactly ten times the resistance of each of the left hand coils of the
right hand pair.
For a long range potential metor, I place such a series of two pairs of ten in a
convenient receptacle, under lock and key, below the galvanometer with a permanent
connection between one end of the galvanometer coil and one main terminal of the
resistance coils, and with a proper appliance for connecting with the other end

page_text: of the galvanometer coil, and the other end of the resistance coils, the two electrodes
leading to points whose difference of potentials is to be tested, and for readily
reversing these connections.
To measure currents supplied by the dynamo of from half an ampere to several
thousand amperes, I use a galvanometer with two circular coils of thick copper rod
or slip, in circuit with one of the mains, and a needle suspended centrally between
them. To regulate to any degree the stability of the needle in its zero position, I
use a fixed electro-magnet, in the manner described in the twentieth part of the
Specification filed in pursuance of Letters Patent granted to me N° 329 A.D.
1858., and represented in Figure 6, of the Drawings of that Patent.-I now make
the coil of this magnet of fine German silver wire, wound on a single bobbin of
brass or other suitable material, and placed between the two thick copper coils,
with its magnetic axis as nearly as may be perpendicular to the magnetic axis of
those coils. The essential part of this condition is, that the vertical planes con-
taining the lines of electro-magnetic force at the centre of the needle or system of
needles, shall be as exactly as possible, mutually perpendicular to one another.-To
allow adjustment to fulfil this condition, the brass bobbin carring the fine wire coil
is capable of a slight motion round the vertical of the suspension of the needle.-I
provide also an adjusting magnet, by which, when the instrument is placed for use
in any locality, the magnetic force on the needles whether due to the earth, or to
fixed magnets in the neighbourhood, may be readily counterbalanced with sufficient
accuracy, to render its effect insensible in the measurements made by the instru-
ment. When this has been done in any place, the azimuthal adjustment of the
fine wire coil is made once for all, as follows: A current from any convenient
source is kept running constantly through the fine wire coil; equal currents in
opposite directions are sent through the circuit of the thick wire coils, and the
brass bobbin is azimuthally adjusted, until the deflections are found to be equal on
the two sides of the position in which the needle or system of needles rests when
the current through the thick wire coils is annulled, and that through the fine wire
coil is kept flowing.
The instrument has also an adjustment of the graduated circular scale, by which
its zero is brought exactly to the position in which the pointer rests under the
influence of the current through the fine wire coil, when there is no current through
the thick wire coils-When the instrument is to be used through a wider range
than admits of convenient measurement with one grade of sensibility, different
grades are given by resistance coils, conveniently fixed in the base of the instru-
ment, and arranged to give very readily one or other of a small number of
definite resistances, exactly suited for each grade of sensibility to be provided for.
It is generally most convenient to use the difference of potentials between the
two mains, for producing the current through the fine wire coil.-As long as the
difference of potentials remains constant, the reading of the galvanometer (sup-
posed graduated according to tangents) is simply proportional to the strength of
the current, but if the electro-motive force varies, the readings will be proportional
to the reciprocals of the resistances in the circuit through the thick wire coils and
the mains This will, in a system of incandescent lighting, be very nearly in
simple proportion to the number of lamps of one type on the circuit at any time,
and accordingly I prefer in many cases to adjust the sensibility of the instrument
by giving the proper resistance to the fine wire controlling coil itself, in the
construction of the instrument or by adding the proper amount of resistance to it,
by means of the resistance coils in the base of the instrument, so that the number
of lamps on the circuit at any one time, may be read off with great ease without
any troublesome calculation, from the number shewn by the pointer on the
circular scale.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Sir William Thomson in the Great Seal Patent Office on the
20th October 1883.
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 "IMPROVEMENTS IN APPARATUS AND PROCESSES
FOR GENERATING, REGULATING AND MEASURING ELECTRIC CURRENTS
33
My said Invention relates to improvements in apparatus and processes for
generating, regulating and measuring electric currents.
In generating electric currents according to my said Invention I use a dynamo
whose armature consists of radial bars of copper, disposed like the spokes of a
wheel about an axis which may be either horizontal or vertical.-These radial bars
are metallically connected at their outer ends by a copper band or other suitable
connection forming the periphery as it were of the wheel, and throughout their
length they are insulated from each other, their inner ends being metallically
connected each to properly insulated commutator bars.
paper
One form of my improved dynamo machine, having the axis of rotation of the
armature vertical, is shewn on Sheets 1, and 2, of the accompanying Drawings; in
which Figure 1, is a section through the axis and perpendicular to the in
the view given in Figure 3, which is a front elevation of the said dynamo.-
Figure 2, is in part a horizontal section and in part a plan of the armature perpen-
dicular to the axis of its rotation.-In the machine represented at Figures 1, 2, and
3, of the Drawings, the armature is composed of 192 radial bars, making with the
insulation between each a solid wheel or disc of about one hundred and twenty
(120) centimetres diameter.-The form and dimensions of the radial bar adapted to
this construotion of armature, is shewn by the parts marked a, in Figure 1, and 2;
the dimensions in the plane of the paper as in Figure 2, are such that when the
bars are laid side by side as there illustrated, with insulating material of an
uniform thickness of decimal one (0.1) millimetre between each bar, they form a
solid wheel or disc having a thickened central portion or boss with a hole through
it. The dimensions of the radial bars of the armature in the plane of the paper as
in Figure 1, are such, that the sectional area of each radial bar in a plane perpen-
dicular to its length is constant for each point of the length; that is to say, that as
each bar decreases in thickness towards the axis of the armature, it increases in
width. Thus the conductivity of the radial bar, is not reduced by the wedge-like
form as shewn in Figure 2, but is maintained at the value obtainable from the
cross section of the bar, at the end next to the periphery of the disc-An annular
projection b, on the shaft o, supports a gun metal casting f, which forms a seat for
the disc-armature; while a rim projecting downwards from it, constitutes the belt
pulley for communicating rotation to the armature.-A screw on the shaft c, with
a long screw-nut d, serves by means of the collar e, to press the disc-armature
firmly against its seat f, and thus secures the condition that the shaft c, disc-
armature a, and seat f, rotate as one body.
The edge of this disc-armature a, consists of a copper ring or hoop, in metallic
connection with each of the radial bars constituting the armature. In certain
circumstances the hoop might be of such form and dimensions, as to resist the
whole or part of the centrifugal force, or tendency to fly out, generated in the
radial bars by the rapid rotation of the armature (about two thousand (2,000)
revolutions per minute); but at present I prefer to provide for this resisting force,
by other arrangements hereinafter described, and to make the cross section of the

page_text: aforesaid copper ring or hoop, only sufficient to give the necessary conductively.
The ends of the radial bars are each secured in metallic connection to this ring or
hoop, say by means of screw pins or soldering, or, as I sometimes prefer, by a web
projecting inwards from the inside of the copper ring or hoop and fitting into a
narrow deep groove formed in the centre of the periphery of the disc-armature.
-
In the arrangement of this form of dynamo which I at present prefer, where
the magnetic fields are so situated, (see position shewn by dotted lines in Figure 2,)
that the radial bars of the armature, passing through them at any instant, are
at opposite ends of a series of contiguous diameters, the commutator brushes; (not
represented on the Drawings,) are carried by a frame-work capable of rotation
round the axis, and so that the portions of their surface, making contact with the
radial bars are diametrically opposite to each other with reference to the disc.-
The brush frame is capable of a motion about the axis of rotation of the armature,
so as to permit the "lead" of the brushes to be adjusted to the proper amount.-
The brushes used may be of any of those forms, described in the Specification filed
in pursuance of Letters Patent N° 5668, A,D, 1881, granted to me the said Sir
William Thomson, and may be arranged to make direct contact on the radial
bars themselves, by utilizing part of the surface of the disc armature as
a commutating surface. At present however, I prefer to construct a commutating
surface of cylindrical form, coaxal with the axis of rotation of the disc-armature,
as follows: a slip of copper, or of any other metal of good conductivity, say for
example, twenty (20) centimetres long by about 2.54, centimetres broad, herein-
after called a commutator bar, is secured in metallic connection with each radial
bar of the armature, in such a position that when the said armature is constructed,
and an insulating material of about decimal one (0.1) millimetre is placed between
each commutator bar, the commutator bars with their insulation form a hollow
cylinder surrounding the aperture in the disc-armature, through which the shaft o,
passes, at a distance, in this machine, of about five (5) centimetres between the
axis of rotation and the inner surface of the cylinder. These commutator bars are
represented in Figures 1, 2, and 3, at g; a washer h, fastened to the nut d, serves
to secure the upper ends of the commutator bars, while insulating material of the
requisite thickness prevents contact between them and either the washer h, or
nut d, or collar 6. A rectangular recess about one half (t) centimetre deep by
five (5) centimetres wide is cut on the lower end of the outer surface of the com-
mutator cylinder, and in it is placed a gun metal ring i, (insulated from the com-
mutator bars and from the disc-armature,) about five (5) centimetres wide and
one centimetre thick.-This ring, shewn in section at i, Figure 1, has a screw
thread formed on its outer surface and is cut at one point of its circumference, and
sprung into position, or may be put on in two halves.-A heavy gun metal ring j,
is screwed down on the ring i, thus securing the commutator bars against cèntri-
fugal force. By means of a projection on the under surface of the ring j, which
fits into a similar recess on the upper surface of the disc-armature, together with
a similar projection on the surface of the gun-metal seat f, and a recess on the
underside of the disc-armature, the necessary resisting force is provided to
counteract the centrifugal force, or tendency of the radial bars to fly out by
virtue of the rapid rotation of the disc-armature.-The disc-armature is insulated
from the ring j, the shaft c, and the seat f, by a sufficient thickness of insulating
material.
In my improved dynamo, the current is induced by the motion of the radial bars
constituting the disc-armature, across the lines of force of permanent magnets or
electro-magnets, so placed as to give fields of force with lines approximately
perpendicular to the plane in which the radial bars of the disc-armature move.
-When electro-magnets are used, I prefer the form shewn by the parts
marked kl, and r, in Figures 1 and 3.-The electromagnets are two in
number, the core of each being formed of a round bar of soft iron, of, say i
for example, twenty centimetres diameter bent to the form of a semicircle of
about sixty (60) centimetres radius on the outer surface.-The two electro
-

page_text: magnets are supported by means of a framework, in such a position as
together to form as it were a large ring supported vertically, and cut in two by
intersections in a horizontal plane passing through its centre. The arrangement
is shewn by reference to the section Figure 1, and the front elevation Figure 3.-
The cores of the magnets are represented at k and l.-The lower one k, is secured
to the framework m, by a wrought iron strap n, and by means of a projection
from the underside of this strap, the whole weight of the lower electro-magnet is
borne on a solid iron block forming part of the frame m,-A recess is cut in the
outer surface of each end of the core k, to receive part of a projection on the gun
metal block o, and a similar recess is cut on each end of the core l.-The two
blocks o, are then placed in the recesses cut for them in the core k; the upper core l,
is placed so that the recesses in it engage with the projections on the blocks o, and
thus the upper core l, rests upon the lower core k, by means of the blocks o, so
that an uniform space is left between the iron faces of the cores for the magnetic
field in which the disc-armature a, moves.-The bolts securing the blocks o, to the
frame m, only prevent the electro-magnets taking any rotation round a vertical
axis in respect to the whole framework p. and m, and do not support any portion
of the weight of the upper electro-magnet.-The iron strap q, prevents any move-
ment of the upper core, round a horizontal axis through the points of support in
the blocks o-Pole pieces 7, are placed on the ends of the iron cores k, and ɩ, and
are made moveable.
The shaft c, carrying the disc-armature with commutator bars, rotates about a
vertical axis, within two bearings fixed on the frame m, in such a position, that
the thin part of the disc passes easily through the space between the poles of the
two electro-magnets k, and l.
On account of the high rate of speed at which the disc-armature moves, an
effective method for lubricating the bearings is necessary.-That illustrated in
Figures 1, and 3, I find both effective and economical of the lubricant.-For the
foot-step bearing, a cylindrical cavity is prepared in the casting t, into which is
fitted a bush u, of gun metal or other suitable material.-In the bottom of the
cavity are placed loosely three hard steel rings forming a step for the shaft c;
the lower end of which is slightly convex, and has fitted in its centre a hard steel
cylindrical plug, say for example about 2-5 centimetres long and 2.5 centimetres
diameter. Two holes are bored from the outside into the bottom of the cavity;
one of them, fitted with a screwed plug, being used for running off the grit, which
is effected by flushing the bearing with oil; in the other hole is fixed one end of
the siphon tube v.-The casting t, forming the socket for the bearing is widened
out at the top surrounding a part of the shaft c, on which there is a sharp edged
annular projection w, designed to prevent oil from creeping up the shaft c.-The
lubrication is effected by pouring the supply of oil or other lubricant into the
vertical limb of the siphon v, and keeping the free level in that tube at or near
to a certain mark, when the hydrostatic pressure will ensure the same height of
free level in the bearing; and hence by properly placing the mark on the vertical
limb of the tube v, the lubrication of the footstep bearing is perfectly secured.→
The only risk of leakage and consequent fall of free level, is from the flashing hole
filled by the screw pin, or by the attachment of the siphon v, both of which may be
made practically oil tight.
For the upper bearing I use a different arrangement, shown in Figure 1, in which
the part marked x, is a cast iron bearing fixed to the frame m, and having fitted
in it the bush y, of gun metal or other suitable material.-Surrounding the upper
end of the bush y, there is an enlarged annular cavity, the sides of which are
curved inwards.-To the washer h, there is fixed an annular oil vessels, surrounding
the shaft and with its sides also curved inwards, but leaving sufficient space between
them and the bearing to clear the oil tube a¹.
The tube a', is a piece of brass or copper tube fixed to the cast iron bearing and
acting as a Pitot scoop.-Its lower part is bent in under the curved side of the oil
vessels, and the opening at this end is in a position, as near as possible to the

page_text: wall of the oil vessel at its widest part, and facing in the direction opposed to the
direction of rotation of the oil vessel.-The upper end of the tube a¹, is bent over
into the cavity in the top of the bearing.-Oil draining from the bush y, is
retained by the oil vessel z, where in consequence of the rotation of the vessel, it
rests with its free surface approximately a vertical cylinder and is scooped up the
oil tube a', and forced through it into the cavity above the bush.-There is thus
provided a continual circulation of oil between the bearing surfaces. A diaphragm
across the centre of the upper cavity prevents the oil in it at any time, from taking
any considerable rotary motion such as it might acquire from the upper end of the
rotating shaft, which forms part of the bottom of the oil cavity.
The frame work m, supporting the electro-magnets and the rotating disc-
armature is stiffened by two triangular brackets p, Figure 1, secured by screw
bolts b', that is to say, one bracket to each of the vertical sides.-The machine is
supported on four wheels c', placed as shewn at Figures 1, and 3.-Rectangular
grooves on the surfaces of these wheels, engage in rails placed on inclined planes
or on inclined bearing surfaces, such as the inclined faces of wedges, resting with
their other faces on a horizontal floor; which arrangement I use for tightening the
belt through the gravitation force of the machine itself when so placed.-When it
is not convenient to use inclined planes the belt may otherwise be tightened by
a horizontal force applied by a spring, or by a rope pussing over a pulley and
stretched by a weight.-In some cases I hang the dynamo by rods or chains from
above, with guides to prevent it from having more than one degree of freedom to
move; or I otherwise secure the same conditions by supporting the machine on
"rocking curves," so that it has a tendency to movement by its own weight, and I
utilize this tendency or that of a rope passing over a pulley and stretched by a
weight, to keep the belt sufficiently tight.
As regards this part of my Invention I desire to observe that the details of
construction which I have herein before described may be varied and that I do not
limit myself to the precise arrangements set forth and shewn at Figures 1, 2, and 3,
of the accompanying Drawings but what I consider to be novel and original, and
therefore claim in respect of this first part of my invention is :-
First. The wheel dynamo substantially as herein before described with reference
to Figures 1, 2, and 3, of the accompanying Drawings and in particular the
construction of the disc-armature with the conductive connection between the
outer ends of the spokes, and the conductive connections between their inner
ends and commutator bars or their equivalent and thence through brushes to
fixed electrodes.
Second-Supporting a dynamo by means of wheels or on rocking curves, these
wheels or rocking curves resting on the inclined planes of wedges; or hanging it
by means of rods or their equivalent with or without the aid of tightening ropes,
for the purposes and in the manner hereinbefore described.
To regulate the potential produced by a dynamo I use the apparatus shewn at
Figures 4, 5, 6, 7, 8, 9, and 10, Sheets 3, and 4, of the accompanying Drawings
A shallow cylindrical drum d', partially filled with oil, is fixed on a vertical shaft c¹,
capable of being rapidly rotated by a driving cord, acting on the V-grooved
pulley An upper bearing for the shaft e', is provided by the bar g¹, fixed to
the supports h¹, and i', and bent into the interior of the drum d², through a circular
aperture in the cover thereof.-A pair of toothed wheels j', and k³, gearing into one
another, and with their shafts , and m¹, Dearly vertical, are supported in the
interior of the drum by.a framework n³, pivoted on the axis o², and capable of a
small oscillation in the plane of the diagram Figure 6.--The drum d', containing
the oil is kept rotating at a high speed, by virtue of which rotation the free surface
of the oil assumes the form of approximately a vertical cylinder, and according as
the frame n¹, currying the wheels j¹, and k', is caused to take a position to one side
or the other of the position of rest, one or other of the wheels 7, and k', gears into
the oil surface, and takes from it a corresponding rotation.-The turning motion of
these wheels is communicated through the pinion pl, fixed on the shaft ♬, and the

page_text: crown wheel q', to a shaft r, which carries a grooved pulley 8', by which a cord
may be pulled in one direction or the opposite, according as the rotation is in the
one direction or the other.-The motion of the frame n², is effected by any of the
known methods of producing a controlling action by electric or electro-magnetic
appliances.
One arrangement of apparatus by which the mechanism illustrated in Figures 4,
5, 6 and 7, may be used to regulate the potential due to a dynamo, is shewn in
Figures 8, 9 and 10, sheets 4, and 5 of the accompanying Drawings, respectively
in side elevation, plan and transverse section.-A series of insulated studs t¹,
constituting an inclined plane surface, form one of the inclined sides of a channel
of triangular section; the other side consisting of an equally inclined solid plate
of copper or other conducting metal.-A number of resistance coils u', one less in
number than the number of studs, are joined in series; the junctions of the series
being connected to the studs as shewn diagrammatically in Figure 8.-v¹, is a
rolling brush making metallic contact between the two sides of the channel, and
constructed according to the principles described in the Specification filed in
pursuance of Letters Patent granted to me N° 5668, A.D. 1881, and having its
contact surfaces inclined to fit the inclined sides of the channel-A suitable
framework on the rolling brush v₁, serves for the attachment to it of one end of
a cord w, one or two turns of which are taken round the grooved drum 8¹,
(Figure 5,), and from the other end is suspended a dash pot, which being a well
known mechanical arrangement is not shewn in the Drawings.-The terminal
wire a¹, is connected to that end of the series of studs t¹, which is in the higher
position, and the terminal y', to the plate -By this means I provide a metallio
circuit between the terminals x¹, and y', of a variable resistance increasing from
approximately zero to any necessary amount, according as the contact roller moves
down the inclined surface formed by the studs t¹.
When electric potential or current is to be regulated the action of the instrument
is as follows:-The controlling force, which is the difference between an electric or
electro-magnetic force due to the actual potential or current at any instant, and its
value when the potential is at exactly the right degree, is applied through the bar
represented by dotted lines at a³, in Figure 4, so as to deflect the frane n', causing
the pulley 8, to revolve in one direction or the other, and by means of the cord w²,
pulling the contact roller v¹, up the inclined channel, or allowing it to roll down,
thereby diminishing or increasing the resistance between the terminals ¹, and y¹,
according to the regulation required.-There are several methods by which the
circuity, may be joined up in an installation, so as to effect the regulation
by the resistance between the two terminals-In the case of a dynamo whose
electro-magnets are excited by a derived current I place the circuit . - - - y', in
series with the exciting conductor of the electro-magnet.
The arrangement hereinbefore described may also be used when ourrent, instead
of potential, is to be regulated. It may be also used as a power-relay in any case
in which it is desired to cause a large adjusting force, to act, in one direction or the
other, under the control of a comparatively delicate motion with small moving
force.
As regards this part of my Invention what I claim is :-
-
The potential regulator with its details of toothed wheels gearing into liquid in
a centrifugal channel; the latter being also applicable as a power relay in other
cases where variations of a comparatively small force are to control a large
regulating force.
When the potential to be regulated is that of an installation of electric lighting
by incandescent lamps, and when a large number of lamps are to be simultaneously
extinguished, the rise of potential due to a sudden simultaneous extinction might,
before the regulator has time to bring the potential back to the proper amount, be
so great as to injure or destroy other lamps.-In such cases I use an appliance by
which the extinction is effected by automatic gradual insertions of resistances,
lengthening the time of the extinguishing to five or six seconds, or whatever may

page_text: be necessary according to the speediness of the action of the regulator, to allow the
potential to be regulated, so as not to rise injuriously during the extinguishing.—
One mode of effecting this, which I find convenient, is by a roller, containing a
hollow having radial partitions, and partially filled with mercury which flows
slowly through small apertures in the partitions, when the roller rolls down an
inclined plane.-The rim of this roller, which may be of brass or of copper or of iron
gilt, makes contact between a continuous metal surface on one side and a set of
studs with surfaces nearly in one plane on the other side; these two planes form
the inclined sides of an inclined groove or channel down which the roller rolls when
it is extinguishing the lights.-When the roller approaches the lower end of its
range it rolls off the lowest stud and on to a non-conductor and thus breaks the
circuit. When it is at the top of its range, it makes contact for the lamps with as
little resistance as possible; and as it rolls down it throws in more and more
resistance by resistance coils connected with the studs.
-
The arrangement of this instrument which I at present prefer is shown at
Figures 11, to 15, (inclusive) on Sheet 6, of the accompanying Drawings, wherein
Figure 11, is a front elevation shewn partly in section, Figure 12, a transverse
section taken on the line C, D, (Figure 11,) Figure 13, being a plan of the said
apparatus and Figures 14, and 15, longitudinal and transverse sections respectively
of a portion of the said apparatus.-An inclined triangular channel or groove is
formed, having for one of its inclined sides an insulated solid copper plate 62, and
for the other side an inclined plane consisting of a series of insulated studs c³-
The channel is prolonged horizontally at its upper end by the two insulated plates
of copper de, and e³, and at its lower end, by the two inclined surfaces f', of wood
or other non-conductor.-A series of resistances g³, are formed of platinum or other
wire, enclosed for safety in glass tubes bent into U-form.-The resistances in the
tubes are graduated, being less towards the upper end and increasing towards the
lower end of the inclined channel.-The one terminal of this series is connected to
the plate e', and the other terminal to the end stud at f, while the intermediate
junctions are connected each to its corresponding stud, all as shewn in Figure 11.-
The plate d², is metallically connected to, or is continuous with the plate b³.
The contact roller h³, (shewn more particularly in section at Figures 14, and 15,)
is of thin copper and in the form of a section of a sphere.-Its interior is divided
by twelve radial diaphragms i³, communication between each two contiguous spaces
being made by means of a small hole, in each diaphragm near the circum-
ference. The contact roller h³, is filled to nearly half its capacity with mercury k³.
The action of the instrument is as follows:-One of the main leads supplying
the group of lamps, the extinguishing of which is to be regulated, is cut and the
ends connected to the terminals l, and m³.-The contact roller h³, rests stably on
the part of the channel formed by the horizontal planes d³, and e³, and so makes
contact for the lamps with as little resistance as possible, but if displaced from
that position it becomes unstable and rolls slowly down the channel until stopped
by a suitable stop n³, when it rests with the circuit broken.-The rolling motion is
nade slow by reason of the time required to permit the mercury k³, to dow by
means of the small holes 5, in the diaphragms i, from one space to the next, and as
the roller h³, passes slowly from stud to stud, it places in the circuit an incre sing
addition of resistance, thus decreasing the intensity of the light until the current
is completely shut off by the contact roller reaching the non-conducting surface f³.
As regards this part of my Invention what I claim is:-
The Blow extinguisher constructed substantially as hereinbefore described, with
reference to Figures 11, to 15 (inclusive) of the accompanying Drawings.
For a current integrator or Coulomb meter, I use a one-wheel carriage,-wheel-
barrow, as I call it, for the sake of brevity-on a horizontal disc, which is kept
rotating uniformly.-The wheel of the barrow, has a curved rim, broad enough
and with large enough radius of curvature to support the wheel-barrow stably,
when the crown of the cup hereinafter described as attached to the barrow is
supported on a radial point in a prolongation of the bearing plane.

page_text: As an alternative form instead of using a wheel having a broad rim, I sometimes
prefer & wheel having a very narrow rim, a mere edge, and in this case obtain
the requisite stability, by arranging that the centre of gravity of the wheel-barrow,
shall be situated in a point at some distance below the plane of the rotating disc.-.
With either form of wheel the weight to be supported is so distributed among the
parts of the framework, (like those of a common hand-wheel-barrow,) that if left
to itself on a horizontal plane, one end of it would rest on the plane.-This end is
supported by means of a fine point and cup (like the point and cup of an ordinary
magnetic compass).-Supposing the cup to be fixed, mouth down, to the barrow,
the point, supported on an arm, is attached to or connected with the moveable
body of an electro-magnetic arrangement (a powerful enough galvanometer) giving
it horizontal motion in one direction and the opposite when the current increases
and diminishes.-The displacement of the bearing point from its zero position
ought to be as nearly as possible in simple proportion to the strength of the current,
and as nearly as may be in a horizontal straight line in a prolongation of the
plane of the rotating disc.-The crown of the cup attached to the barrow ought to
have as nearly as possible the same distance from the point, in which a tangent
plane through it to the rim of the wheel meets the rim, that the line of motion of
the bearing point has from the centre of the disc.-If this last condition could be
rigorously fulfilled, the zero position of the bearing point might be exactly at
the point in its line of motion nearest to the centre of the disc,-With these
adjustments all rigorously carried out, the angle turned through by the wheel in
any time, would be exactly proportional to the desired time-integral of the current,
if the variation in strength of the current were infinitely slow. The direction of
rotation of the disc must be such that its motion is from the bearing point when
displaced from zero by the current to be measured.-When the bearing point is
displaced from its zero, the motion of the disc draws the barrow into the proper
place for integrating the current, and the pull of the barrow produces no disturbance
of the position to which the electro-magnetic force tends to bring the bearing
point. A suitable mechanical arrangement is applied to the wheel of the barrow
and carried by the barrow itself, by which the number of turns made by the
wheel in any given time may be read off, which number gives the integral of the
current for that time.
I sometimes adjust the zero of the bearing point to a little away from the point
in its line of motion nearest to the centre of the disc. Thus, when the current to
be measured is zero, the wheel of the barrow is kept turning at a slow constant
rate as long as the disc is kept rotating.-A counter, of any of the well known
kinds, decimally arranged, is applied to the wheel-work turning the disc so as to
register the number of turns made by the disc in any time.-The numbering of this
counter is so related to that on the wheel-barrow, and the zero of the electro-
magnetically moved bearing point is so adjusted, that the readings on the two
counters grow equally as long as the current to be measured is zero.-The integral
of the current in any time is therefore the excess of the increase of the reading
of the barrow-wheel counter above the increase of the reading of the disc counter.
The sensibility of the electro-magnetic controller is adjusted, so that the number
given by the wheel barrow counter as in the former adjustment, or by the difference
of the readings of the two counters as in the latter adjustment, is the number of
coulombs, or of other chosen unit, expressing the whole quantity of electricity that
has passed through the instrument in the time.
The electro-magnetic controller may be adapted to stop the wheel-work whenever
the current becomes less than the smallest that the user can take advantage of, as
for instance that of a single lamp, or of the smallest number of lamps of an
installation of electric lighting.
To secure that no current shall pass unmeasured, a make-break appliance is
introduced into the main circuit, by which when the weight or spring which drives
the wheel-work runs down to near the end of its range, the circuit is broken and
can only be re-made by winding up the weight,

page_text: The whole apparatus of counter wheel-work and this make-break adaptation,
are to be kept under lock and key, or otherwise secured against intentional or
unintentional mal-adjustment.
The wheel-barrow integrator as herein before described is shewn in Figures 16,
17, 18, 19, 20, 21, and 22, Sheets 7, and 8 of the accompanying Drawings.-The
disc o³, is kept rotating at a uniform rate by means of the clock-work mechanism p³,
controlled by a governor 9.-The wheel-barrow ³, with a broad rim wheel &³,
and train of counter wheels, is shewn in position at the centre of the disc o³.—A
little arm t², projecting from one end of the wheel-barrow has fixed to it an inverted
cup u³, in such a position that a tangent plane to the top of the cup is coincident
with the plane surface of the disc.-The arm v2, fixed to the moveable part of the
electro-magnetic arrangement, to be hereinafter described, carries a bearing point
within an orifice at a certain position, so situated that the top of the bearing point
is in a plane coincident with the plane of the rotating disc.-This point carries the
free end of the wheel-barrow by means of the cup u³, resting on it. The electro-
magnetic arrangement used may be of any of the known forms, in which the motion
of the moveable part is simply proportional to the current.-The form shewn at w³
is that of a rectangle pivoted on an axis, mid-way between and parallel to its
longer sides, and so arranged that it can be introduced as part of the circuit, the
current in which is to be integrated.-The two spaces in which the longer sides of
this rectangle move are made powerful enough magnetic fields of opposite character,
by means of a series of horse-shoe magnets ³, spanning the outside and short
bar magnets placed in the interior of the space about which the rectangle moves.
An arm y³, fixed to the rectangle is secured to the spiral spring 2³, which gives
a means of adjusting both the zero of the arm moving the carriage, and also the
sensibility of the arrangement producing the electro-magnetic force to actuate the
integrator. As shown more particularly at Figure 19, the screw a³, carries on its
upper end a small plate or ring with three arms b³, projecting from it, secured against
longitudinal motion but capable of rotation about it as an axis.-Each arm has in
it a hole, at a proper distance from the centre and large enough to fit the wire of
the spring The arms 6º, are screwed on the spring z³, thus connecting it to the
screw a. The adjustment of the zero is made by means of a milled head pro-
ducing a longitudinal motion of the screw a³, while the adjustment for sensi-
bility is made by turning the arms 6*, thereby altering the effective length of the
spring.
The lower end of the arm v³, is bent so as by means of the arm c³, secured to the
governing shaft &³, to stop the wheel-work p², when the current passing through
becomes less than the amount for the circuit.
A convenient arrangement of any well known kind is fitted to the integrator,
by which when the motive power driving the wheel-work becomes spent, the
current is broken and can only be re-made by restoring the motive power.
As an alternative I sometimes use with this integrator the carriage shewn in
Sheet 8, Figures 20, 21, and 22, which views respectively represent the said
carriage in front elevation, side elevation and plan. The main features of it are
the integrating wheel, the rim of which is reduced to an edge; and the construc-
tion of the carriage, by which the requisite stability is secured by arranging that
the centre of gravity is very low.-The cup support is shewn at f³.-The counting
is effected as shewn by screws g³, cut on three shafts working on corresponding
wheels, each having one hundred teeth -A counterpoise of lead or other
heavy metal is represented at j.
As regards this part of my invention what I claim is :-
The one-wheel wheel-barrow integrator or coulomb meter, constructed sub-
stantially as and according to either of the two varieties herein before described
and shewn at Figures 16, to 22, (inclusive) Sheets 7, and 8, of the accompanying
Drawings.
As an alternative method for integrating I use a gyrostatic system as follows:-
A framework moveable round a fixed shaft, carries a second framework jointed to

page_text: it so as to be moveable relatively to it round an axis perpendicular to its axis.-
This second framework bears pivoted upon it a flywheel, and for brevity I call it
and its fly-wheel, the gyrostat.-The axis of the fly-wheel which is perpendicular
to the axis of the first mentioned shaft, bears a pinion worked by a crown wheel,
or preferably a small disc bearing on the plane surface of a disc co-axal with the
first mentioned shaft.-The framework carrying the gyrostat is caused to rotate
uniformly at a speed accurately regulated by a frictional or other governor.-The
line of the axis round which the framework carrying the fly-wheel can turn should
pass through the point of contact, between the teeth of the pinion and of the
crown wheel, or between the two discs when the frictional method of transmitting
the motion is preferred.-When the crown wheel or disc rotates at the same speed
as the first mentioned framework, the fly wheel gets no rotation.-The crown wheel
or disc is caused to rotate faster than the bearings of the gyrostat, the difference
of speed being regulated so as to be in simple proportion to the controlling electro-
magnetic force.-This is effected by means of a tilting motion of the gyrostat
under the influence of the controlling electro-magnetic force, which is applied to
act on a point of the gyrostat as nearly as may be in a prolongation of the axis of
the first mentioned shaft.
When the controlling force is just overbalanced by the tilting tendency of the
gyrostat, a point on the gyrostat is caused, by the tilting motion, to press on a
fixed plane or bar, and so to produce friction enough to stop further augmentation
of speed. A spring between the gyrostat and the framework on which it is
pivoted, may be adjusted to control the tilting motion when gravity and centri-
fugal force are not conveniently or sufficiently available.-A counter which counts
the number of turns of the flywheel gives a reading in simple proportion to the
quantity of electricity which has passed in any time.
As a governor to regulate the rotation of the framework, use a second gyrostat,
carried by a frame jointed to the main frame in a similar manner to that of the
first mentioned gyrostat.-The tilting motion of this second gyrostat, is utilized to
bring into action a frictional retarding force, preventing the speed of rotation of
the framework from becoming greater than a certain amount.
The arrangement and details of the gyrostatic integrator which I prefer are
shewn at Figures 23, 24, 25, and 26, Sheets 9, 10, and 11 of the accompanying
Drawings, which Figures represent the said gyrostatic integrator respectively in
front elevation, side elevation, and sectional plans.-The framework k³, is supported
on the disc P, by the carriage m³, and its one wheel n³, and is moveable about a
fixed shaft o, coaxal with the vertical loose shaft p-A pointed arm q³, con-
stituting part of the framework ³, supports a second frame by means of an
inverted cup bearing s³, fixed to it.-A heavy flywheel &, has its shaft u³ pivoted
on the frame, so as to be capable of rotation about an axis passing through the
axis of the shaft p³, and perpendicular to it.-The frame with its fly-wheel t³,
I for brevity term the gyrostat.-This gyrostat is supported on the horizontal
disc l, by a disc, fixed to the shaft u, of the gyrostat wheel, and is capable of
motion about an axis passing through the bearing point s³, and the point of contact
of the vertical disc, on the horizontal diso ; which axis is also perpendicular to
the axis of rotation of the gyrostat wheel -A plate w³, fixed to the gyrostat hus
a hole in it fitting easily around the loose shaft p³, and by means of the collar x³,
fixed on the shaft p, supplies a means of giving a slight tilt to the gyrostat about
the axis through the bearing points, and the contact between the discs l, and v
as before mentioned. A bar yo, constituting part of the framework, has its end
in such a position that it touches the rim of the gyrostat wheel, when this tilt
reaches a given amount.-The weights in the gyrostat are so arranged that this tilt
may be given with as little expenditure of force as may be.
A counting arrangement is mounted on the carriage m³, connected to the
wheel n³, and registers the number of turns made in a given time.
To regulate the speed of the framework k³, I use a gyrostatic governor as
hewn. A gyrostat with its fly-wheel s³, is jointed to the framework, in a

page_text: similar manner to the first mentioned gyrostat.-The axis of rotation of its fly-
wheels, passes through the axis of the shaft p³, and is perpendicular to it, while
the gyrostat itself is capable of motion about an axis passing through the
bearing point a, and the point of contact between the discs 6, and c-The disc o,
is fixed to the fixed shaft o', hence the rotation of the wheel of the gyrostat is
caused by the disc b, rolling in contact with the fixed disc c', in virtue of the
rotatory motion of the framework .-At the regulated speed the upper rim of the
wheel, in the governing gyrostat is just clear of an inclined plane d', of brass,
surrounding its path; but if at any time the speed should increase beyond that
regulated for, the tilt given to the axis of rotation of the wheel of the gyrostat, by
virtue of its azimuthal speed, serves to supply the necessary retarding friction by
pressing the edge of the fly-wheel ³, against the metal rim d'.
The action of the gyrostatic integrator is as follows:-Any convenient
mechanism is applied through the pinion e, to rotate the shaft f*, bearing the
disc -This motion is communicated to the framework k³, by means of the
integrating wheel n³.-The controlling force due to the current to be integrated,
is applied as a force pulling (as represented by the arrow g.) vertically upwards,
the loose shaft p-This frees the gyrostat wheel t, from the action of the brake y³,
and allows the disc 18, to rotate faster than the frame-work k³, thus communicating
rotation to the gyrostat wheel to.
This rotation of the gyrostat wheel, compounded with the azimuthal motion of
the whole gyrostat produces the tilting tendency, which is arranged as herein before
described to act as a direct pull, opposed to that produced by the controlling force
through the loose shaft or rod p³-Thus, at any instant, the gyrostat wheel t³, is
rolling over the disc ³, or is at rest relatively to it according as the controlling
force is more or less than the force exerted by the gyrostat frame.-Hence the
number of turns made by the gyrostat wheel t, during any time is directly
proportional to the controlling force exerted by the amount of electricity which has
passed through the electro-magnetic arrangement in that time.
The integration of the current is indicated by a system of counting wheels
geared to the wheel n³, of the integrator carriage and counting its rotation
relatively to the disc 13, and since the integrator carriage with its wheel n³, and
the gyrostat with it flywheel P, have a common azimuthal motion the number
given by the counter measures the rotation of the gyrostat wheel ³, and therefore
the current which has passed through the electro-magnetic arrangement in any
given time.
As regards this part of my invention what I claim is :-
The gyrostatic integrator with its gyrostatic governor or with any other form of
governor for giving uniform speed to the part of the instrument requiring uniform
speed substantially as hereinbefore described with reference to Figures 23, to 26,
inclusive of the accompanying drawings.
I sometimes use the gyrostatic governor herein before described as applied to the
gyrostatic integrator for other mechanisms or mechanical details where accurate
regulation of speed is desired and I claim the gyrostatic governor for such use, that
is to say, separate from the gyrostatic integrator.
The same instrument may be used merely as a speed indicator for observing the
speed at any instant of a Dynamo or of any rotating shaft. For this purpose the
tilting of the gyrostat through a small angle of about 10° for example measures
the speed of the crown wheel relatively to the gyrostat frame.-A lever pressing
lightly on a point of the gyrostat in the prolongation of the axis of the first
mentioned shaft serves to multiply the tilting motion and to shew the desired
speed, on a convenient fixed scale with divisions which are approximately equi-
distant to indicate equal differences of speed.
In adapting the gyrostat to the purposes of a speed gauge the arrangement
differs only in the design of the details from the two instruments last described,
namely, the gyrostatic integrator and its gyrostatic governor and this is represented
in Figures 27, 28, and 29, Sheets 12, 13, and 14, of the accompanying Drawings

page_text: which are respectively, a front elevation part side elevation and in part a plan
thereof. The shaft whose speed is to be measured communicates its rotation by
any convenient method, say through the pinion *, and toothed wheel, to a
horizontal wheel j, rotating about a vertical axis. On this wheel, teeth are
cut suitable for gearing into the pinion *, on the shaft of the gyrostat hereinafter
described. A suitably designed framework 1, is supported so as to be moveable
about an axis coaxal with that of the wheel -A frame m*, carrying a heavy fly-
wheel na gyrostat is jointed at o, and p, to the framework ; the pinion k*,
on the shaft of the gyrostat n', gearing into the toothed wheel -The frame m*,
of the gyrostat is prolonged towards the axis about which the framework 1, moves
and is attached to the lower end of the spiral spring g-It has fixed on it a cup
for receiving the pointed end of the loose rod 8, the upper end of which is
provided with guides t, to permit of vertical motion in the line of the axis of the
frame -The gyrostat n, is capable of a slight motion about an axis through o*,
and p, and the point of contact between the pinion h, and the wheel j, and this
axis is so situated that during such motion the shaft of the gyrostat ne, moves in a
vertical plane perpendicular to the axis of motion and passing through the axis of
rotation of the frame -The centre of gravity of the gyrostat is so situated that
the cup, presses upon the lower end of the spring.-The loose rod a', having its
lower end pointed, rests on the cup, of the said gyrostat, and rises or falls with
the motion of the cup attached to it.-The cord ut, secured to the upper end of
the bars, passes once or twice round the pulley, bearing on its shaft the
pointer w, and has suspended from its end the counter-poise x, of sufficient weight
to make the cord grip and give the turning motion to the pulley v*, according as
the bar 8, is raised or lowered.
When the wheel, is rotated the wheel n*, takes up a rotation about its axis
and the gyrostat frame takes a rotation about an axis coaxal with that of the
wheel In virtue of this latter motion the frame m*, bearing the gyrostat frame
tilts so as to depress the cup *; the amount of the motion being approximately
proportional to the speed of the wheel j; and this motion is, by means of the
mechanism herein before described, indicated by the pointer w, on the dial *,
divided to shew revolutions per minute of the tested shaft. These masses of lead
or other suitable material are suspended by the wires aº, from the three horizontal
bars 6, pivoted on the frame 1, and serve as governors to the motion of that
frame.
As regards this part of my Invention what I claim is :—
The gyrostatic speed meter substantially as hereinbefore described with reference
to Figures 27, 28, and 29, of the accompanying Drawings.
As another alternative method which has the advantage of being applicable to
integrate the average of the current proceeding from an alternate current dynamo,
I use a piece of wheel-work arranged to move with a speed proportional to the
square root of a force, applied to one point of it, which for brevity I call the
controlling force."-This I effect by means of a centrifugal governor partially
constituted of mechanism analogous to Watt's original governor.-The controlling
force is applied to a point of the lever carrying the fork, or equivalent, through
which the influence of the jointed quadrilateral frame is transmitted. This force
is so applied as to counteract the centrifugal force of the governing balls or
masses. When it is underbalanced by the centrifugal force, the governing masses
are held in by it, and press against a ring which is kept rapidly rotating, and
which, by their friction upon it, augments their speed until centrifugal force
suffices to annul their pressures on the moveable ring. They then fly out alightly,
and press against a fixed concentric ring surrounding the space in which they
move, and their friction against this ring prevents any farther augmentation of
their speed, such as friction in the mechanism might cause them to take from the
rotating shaft which carries the moveable ring.-When the mechanism is such as
to give rise to no such frictional force the fixed ring may be omitted. In the form
of mechanism which I at present prefer, -there is such a frictional force; and it

page_text: increases in amount with increase of controlling force; this being arranged for, in
order that with the greatest controlling force to be provided for, the friction of the
governing masses on the moveable ring may suffice to give them their lifting
velocity. In this particular plan of mechanism I therefore use a fixed ring.
Instead of a fork and sliding tube on a continuous spindle, as in Watt's governor,
I prefer to have the spindle in two parts telescoped together, and so connected by
the jointed quadrilateral that when the governing masses fly out the length
between the ends shall be augmented.-This allows to be used instead of a fork, a
mere moveable end plate, pressing on one end of the telescope shaft, which gives
riso to much less friction than the fork.-This end plate may be attached to one
end of a lever which turns through only an exceedingly small angle during the
action of the apparatus: the amount of motion of the end plate itself required for
the governing action being exceedingly small. Thus a small controlling force with
a moderate range of motion, may be applied to give by leverage a much greater
force on the end plate, through its very small range.
The controlling force is to be produced by the mutual action between a fixed
and moveable portion of the conductor, through which the electricity to be
measured passes.-The velocity at which the governing balls are kept turning,
is proportional to the square root of this force, or of its average value when it
alternates with great rapidity between zero and maximum, as it does in alternate
current dynamos; and a train of wheels driven by a pinion or worm rotating with
the governing masses, allows the time integral of the square root of the force to be
read off at any time. This integral is the proper measure of the value of the
electricity supplied during any time, whether from a continuous current or from an
alternate current dynamo.
A convenient mechanism for carrying out the conditions hereinbefore described
is shewn in Figures 30, 31, 32, and 33, Sheets 15, and 16, of the accompanying
Drawings which represent the said instrument respectively in side elevation end
elevation, plan and transverse section.
A conical vessel co, with its upper portion d³, of cylindrical form is capable of
rotating about a vertical axis and constitutes by its upper part the rotating
ring; its motion being governed by two masses e, fixed to its outer surface by
springs Surrounding this, with an annular space between, there is fixed
a cylindrical ring constituting the fixed ring go.-h, is the jointed governing frame
with its two governing masses i, shewn in contact with the rotating ring d³.
-The spindle 7, working within the hollow shaft, transmits to the end plate 1³,
fixed on the end of the lever ms, the centrifugal force of the governing masses ³.
This is effected as follows:-The hollow shaft ko, working loosely on the spindle 7³,
bas a footstep bearing at no, and carries on its upper end a cross bar hinged to the
jointed governor frame h-The spindle 7, has a footstep bearing for its lower end
at o, in the frame p, carried by the hollow shaft k, and has secured to it a cross-
bar go, hinged to the lower part of the jointed governor frame, the upper end
working in a bearing, on the lever m², and abutting on the end plate -Thus
the centrifugal force of the weights, tends to raise the cross-bar q³, and with it
the spindle, thereby increasing the distance between the upper ends of the
shaft ko, and the spindle 7, and giving to the end plate 1, the small amount of
motion required for the governing action.
The lever m, is pivoted at so, and has at its end to, any convenient arrangement
for permitting the application to it of the controlling force while at its opposite
end it carries the counter wheel us, driven by the worm, on the spindle
The rotatory motion of the conical vessel c³, is imparted through the pinion
wheel w, which is secured thereto and which is geared into the toothed wheel o³,
to which the motion is imparted by any suitable mechanism.
In virtue of the balancing action of the controlling force, opposed by means of
the end plate to the centrifugal force of the masses i, the angle turned through by
the wheel u, in any given time, is the time-integral of the square root of the
controlling force-The controlling force is arranged to be as the square of the

page_text: current.-Hence the reading on the integrating wheel is the proper measure of
the integral of current through the conductor up to the time at which it is
observed
As regards this part of my invention what I claim is :-
As an alternative integrator available for electric lighting on the alternate
current system the instrument herein before described and shewn at Figures 30,
to 33, inclusive, giving the time-integral of the square root of the electro-magnetio
current being one method of carrying out a general principle described in the
Specification filed in pursuance of Letters Patent granted to John Hopkinson
N° 49. A.D. 1882.
As another alternative method which has the advantage of avoiding the expense
and wear and tear of wheel-work, I use a stream of water so arranged as to give
into a measuring vessel, a quantity of water simply proportional to the quantity of
electricity to be measured.-For this purpose I produce a fluid pressure varying in
simple proportion to the controlling force, and direct the pressure to cause water to
flow into the measuring vessel, at a rate proportional to the controlling force simply,
or to its square root, according as the electro-magnetic appliance is arranged to
give force proportional to the current or to its square.-In the one case the pressure
forces the water at a slow rate through a capillary tube; in the other case, it
forces it through a wide tube ending in a fine nozzle. In the former case the
water must be kept as nearly as may be at one temperature, because the viscosity
of water is greatly influenced by its temperature being greater at low temperatures,
and less at high temperatures.-To effect this I use a metallic thermometer making
or breaking circuit through a wire of large resistance connecting the two electric
mains, and wound round the space occupied by the capillary tube, and a portion of
a wider tube through which the water enters it.-The metallic thermometer breaks
or makes circuit whenever the temperature is above or below the proper degree.―
In the former case I prefer to produce the required fluid pressure, by causing a
little cistern flexibly connected with the discharging end of the capillary tube, to
be lifted or lowered by the electro-magnetic controller.-In the other case I use a
long wide vertical tube, for example of one metre length and with a fine nozzle at
its lower end, hung on a balance. This tube is lifted very slightly when the
weight of the water within it is too small, and is let down when the weight is too
great, by means of an electro magnetic force produced by a fixed part of the circuit
acting on a moveable part attached to the balance.-The tilting of the balance,
thus produced in one direction or the other, acts by means of an arm or connecting
rod on a feeding nozzle, pushing it to one side or the other, so that water from it
flows into the open end of the vertical tube, or into a waste water drain situate in
its vicinity according as the electro-magnetic force is under-balanced or over-
balanced by the weight of the water in the vertical tube.
Instruments designed to give, according to the methods and principles above
described, the time integral of the electric current flowing in a conductor, by the
proportional amount of water given into a measuring vessel, I term hydraulic
integrators.-The two kinds, differing according as the flow into the measuring
vessel is proportional to the controlling force simply, or to its square root,
distinguish as "oozing" or "jet" integrators.
A form of the bydraulic jet integrator which I find convenient is shewn in detail
in Figures 34, 85, and 36, Sheets 17, and 18, of the accompanying Drawings which
respectively represent the instrument in front elevation, side elevation and part
transverse section on an enlarged scale.-A water cistern yo, is kept supplied with
water, so as to keep the free level approximately at a certain height above the
point within it from which the jet tube 2, draws off the water.-The tube, is in
two parts, flexibly joined together by the india rubber tubing as, and has at its
lower end a fine nozzle.-The frame 6, is pivoted at the points of, and is capable
of a slight motion about a horizontal axis passing through these points.-A wide
tube d, of glass or other suitable material drawn to a fine nozzle at its lower end,
is suspended from an arm or arms e, fixed to the frame befo, is a waste water

page_text: trough. A filler 98, as represented more particularly at Figure 36, is divided by a
diaphragm ho, having a sharp edge, and is placed in position so that this sharp edge
is in the line of flow of a jet of water issuing from the jet tube 2º, when the coil iⓇ,
fixed to the lower end of the frame be, is in a position midway between the two
fixed coils -The tubular part of the filler go, is in position inside the tube d®,
while the scoop directs water falling into it to the waste trough f.-The electro-
magnetic controlling force is produced by means of the mutual action of a fixed
and a moveable portion of the electric circuit, constituted by the two fixed coils 10,
and the moveable coil º, fixed on the moveable frame 66.-The two fixed coils ja,
are connected in series so that the current circulates in the one, in an opposite
direction to that in which it circulates in the other.-The weights 1, on the
frame 6º, and its attachments, are so disposed that the said frame rests in such a
position as by means of the arm me, to deflect the jet tube so, so that the flow of
water is directed into the waste trough fe-Hence in joining the moveable coil 26,
in series with the fixed coils, the current is made to circulate so as to oppose this
gravitational tendency of the frame 6º, and to deflect the tubes, so that the jet of
water is directed through the tubular part ko, of the filler go, into the vertical
tube do. When the instrument is in action the effective head of water in the
tube do, at any moment, is therefore the height of the column of water which
nearly balances the forces called into play by the current then flowing in the coils,
and is proportional to it.-This force is proportional to the square of the current,
and as the outflow of water through the nozzle of the tube do, is proportional to
the square root of the head, the volume of the water which has flowed out in a
given time, is a direct measure of the time-integral of the current.
Any convenient method for measuring the water passing through the tube do,
may be adopted.-One form is shown on the accompanying Drawings, wherein a
Tantalus Cup no, is suspended from the spring 0%, which it gradually extends as
the said Tantalus Cup fills.-When the water in it reaches a certain level it is
suddenly emptied, and moves up by reason of the diminished weight of the
spring.
A mechanical arrangement of any well known form, is actuated by the upward
movement of the cup, to record the number of times it has been emptied during a
given period.
The arrangement of apparatus which I at present prefer for carrying out the
principles and methods of the hydraulic oozing integrator is represented in detail
at Figures 37, and 38, Sheet 19 of the accompanying Drawings, which represent
respectively the instrument in side elevation and in front elevation-The supply of
water in the cistern po, is kept so that its free level is at a certain given height,
the means adopted in this case being the inverted bottle go, containing water, and
fixed so that its open mouth is within the cistern po, and at the surface of the
water, when its free level is at the given height. The tube, which passes out
from the cistern in a horizontal direction, is in two parts jointed by the india rubber
tube at 8º, and is slightly turned down at the free end as represented at f.-This
tube is flexibly connected to a moving part of the electro-magnetic system u°, so
that when the point of connection is in the middle of its path the tube r³, is
approximately horizontal.-The moving part u°, of the electro-magnetic system
with its attachments, must be so weighted that when no current is passing, the
point of connection is at its highest position; and the mouth to, of the tube 5, above
its horizontal position, thus stopping the flow of water along it. A wide tube vº,
terminating in a suitable length of capillary tube wº, is suspended from the moving
part u, of the electro-magnetic system so that the open mouth to, of the tube rº, is
approximately in the axis of the tube v.
The controlling electro-magnetic force is obtained by means of a rectangle
(constituting the moving part u, before mentioned) of heavy strip copper pivoted
so as to be moveable about an axis midway between and parallel to its longer
sides. The motion of the longer sides is arranged to take place in a strong magnetic

page_text: field obtained as hereinbefore described with reference to the wheel-barrow
integrator represented at Figures 16, 17, and 18 of the accompanying Drawings.
The action of this integrator is similar to that of the jet integrator; but it will
be more economical of water in respect of the smaller quantity flowing, and of the
outflow from the cistern being stopped when no current is passing, instead of being
directed into a waste trough. The outflow from the tube v, is proportional to the
"head" in it, and since the electro-magnetic system gives a controlling force in
proportion to the current, the quantity of water that has passed through it during a
given time is a proper measure of the time-integral of the current for that time.―
The measurement is effected by any convenient measuring vessel placed to receive
the drops from the dropping tube of the reservoir a³.
As regards this part of my Invention what I claim is :-
First: As a meter available for alternate current lighting and having the
advantage of avoiding wheel-work mechanism the hydraulio jet integrator
substantially as hereinbefore described with reference to Figures 34, to 36 (inclusive)
of the accompanying Drawings.
Second As an alternative coulomb meter having the advantage of avoiding
wheel-work mechanism, the hydraulic oozing integrator, substantially as herein-
before described with reference to Figures 37 and 38, of the accompanying
Drawings.
To produce the controlling electro magnetic force as required for regulators, or
for current integrators, such as are described in the preceding paragraphs of this
Specification, I employ the mutual action between fixed and moveable parts of
the electric circuit. To effect this practically I use for the moveable portion two
coils in parallel planes, with the current going through them in opposite directions;
in order that the balance may not be disturbed by terrestrial magnetic force, or by
the magnetic force of moderately distant dynamo machines, or other fixed or
moveable magnets in the neighbourhood.-For the fixed portion of the circuit to
act on the moveable portion, I use a flat coil fixed between two moveable coils, and
so proportioned that the distances, from the outer and inner boundaries of the
fixed coil, to the nearest point of the mean circle of either of the moveable coils;
are considerable in comparison with the distance between the moveable coils.-I
sometimes prefer to use for the moveable portion of the circuit one coil, between
two coils in parallel planes constituting the fixed portion-The moveable coil or
pair of coils is so mounted, as to have just one degree of freedom to move; which
should be as nearly as can conveniently be arranged for perpendicular to the planes
of the three coils.-This may be done by knife-edge supports as in an ordinary
balance, or by bifilar suspension. For bifilar suspension I use the torsional
elasticity of each of two bearing wires, by means of two torsion beads, each acting
as the single torsion head in Coulombs unifilar torsion balance, and adding their
torques to bring the moveable body to equilibrium in any marked position.-I use
this method of a double torsion balance also in an instrument otherwise agreeing
with Weber's electro-dynamometer, which I employ for adjusting and testing the
Bensibility of the electro-magnetic appliances by which I produce the controlling
force in the regulator, or for adjusting or finding the constants of the potential and
current meters.
An arrangement for practically carrying out the above method for current,
has been already described in connection with the hydraulic jet integrator.
An instrument on the same principle for gauging the difference of potential
between any two points in a circuit is shown at Figures 39, 40, and 41, Sheet 20,
of the accompanying Drawings, which represent the said instrument respectively
in side elevation, end elevation and in plan.—I term this instrument an idiostatio
bolt gauge. The coils are made of fine wire and are of sufficient resistance to
prevent them from becoming unduly heated by the current passing through them.
-yo, yo, are the two moveable coils carried by the beam 2º, which is pivoted
on knife-edge bearings a-The beam 28, is accurately balanced on the said
knife-edges by the weight b'.-The fixed coil c', is carried by the stand d', so

page_text: as to be midway between the moveable coils yo, when the beam 0, rests horizon-
tally balanced on its pivots.-The two wires e, form the electrodes of the coil o'.—
The two coils 38, yo, are joined together so that the current circulating in one
direction in the one passes, to the other and circulates in an opposite direction in
it. The two free ends of the pair of moveable coils are connected by means of
very fine wire to points in the electrodes f7, as nearly as possible in the axis about
which the beam 2, moves.-Two arms 97, fixed to the beam 20, carry stretched
between them a fine wire h³, which moves over the surface of the scale i serving
as an index of the motion of the beam.-In action any one of the two pairs of
wires f, and e or e², and ƒ7, are joined together, and the remaining pair serve as
two terminals for connecting to the points in the circuit, between which the
difference of potential is to be gauged.-The square root of the weight required
to balance the instrument with its pointer at a chosen position on the scale
measure the potential.
I sometimes make the system symmetrical by placing a similar arrangement of
coils on each end of the beam.
I also sometimes alter the above disposition of the fixed and moveable portions
of the circuit by making the system consist of one moveable coil between two
fixed coils.
I sometimes find it convenient to use as a controlling force, the mutual action
between a portion of the circuit and fixed magnets.-To effect this I use a moveable
ring or rectangle, constituting part of the circuit and two circles, or rows, of
opposite magnetic poles, outside and inside the ring or rectangle, so that the motion
of the ring or rectangle may be approximately perpendicular to lines of magnetic
force approximately along radii of a cylinder. These magnetic poles may be made
of straight bar magnets all parallel to one another, and the other ends may be
magnetically connected, by a soft iron ring between them or the magnets may
may be of horse-shoe form, and fixed so as to have their two poles in the two
circles.
Electro-magnetic apparatus constructed according to this method has been
already described and illustrated in connection with the wheel-barrow integrator
(Figures 16, 17, and 18) and also the oozing integrator (Figures 37, and 38) on the
accompanying Drawings.
As regards this part of my Invention what I claim is*—
The idiostatio current or potential gauge with its two moveable coils and one
fixed coil between them, or alternatively two moveable coils at opposite ends of
the beam each between two fixed coils; in particular the proportions and relative
positions of the coils being as hereinbefore described in connection with Figures 39,
40 and 41, and so arranged as to give approximately equal forces for different
positions of the moveable coil, within sufficient range to allow a pointer to shew
moderate per centage deviations on a scale.
For a potential meter to measure the difference of potentials between the main
conductors of the dynamo, or between any two points of its circuit, I use a coil of
fine insulated german silver wire wound on a bobbin of brass or other suitable
material; or a pair of such coils: the coil or pair of coils being so mounted as to
be capable of being turned slightly round a vertical axis, through the point or
fibre bearing the needle, or system of needles, while the graduated scale remains
fixed; in order that the magnetic axis of the coil may be adjusted into exact
coincidence with the plane through the vertical round which the needle or system
of needles turns and their magnetic axis-This adjustment is performed by trial,
the test being that the deflections produced by equal currents in opposite directions,
shall be equal on the two sides of the position in which the needle or system of
needles rests when there is no current. For supporting the needle or system of
needles, I prefer a simple silk fibre suspension, except when the usage is likely to
be such as to endanger breaking the fibre.-To render the instrument portable
with the silk fibre suspension, I prefer an arrangement by which the point of
support of the upper end of the fibre may be lowered by means of a screw

page_text: mechanism, and the needle or system of needles allowed to rest, supported on a
stout pin passing through a metal ring interposed between, and the bearing fibre.―
As an alternative I sometimes use a special cradle, controlled by a screw for lifting
the system of needles, and pressing it firmly against a roof so as to take the
weight off the fibre.-The upper end of the fibre is attached to a brass tube, which
also carries the lifting mechanism and which can be slipped into its proper position
in the galvanometer bobbin, or removed from it at pleasure. Thus if by accident
the silk fibre suspension is broken, a fresh tube with cradle and suspended needle,
can be instantly supplied to the instrument if the spare appliance is at hand or in
case of need can be sent by post or otherwise to a distant station without danger
of breaking.
To adjust the potential meter conveniently to round numbers of volts I use in
connection with it a special arrangement of resistance coils, which if made suffi-
ciently extensive, suffices also to adjust the instrument to measure potentials
through very wide ranges, as for instance of from one volt to 2000 volts.-A single
standard voltaic cell or a few such cells in series, or any convenient form of
electro-dynamometer, may be used for the primary adjusting and testing of the
galvanometer. The instrument is provided with a controlling steel magnet or
magnets as described in the Specification filed in pursuance of my Patent N° 5668.
A.D. 1881.-I insert in series with the galvanometer coil an amount of resistance
found by trial, so as to produce an exact number of divisions of deflection, with a
difference of potentials known accurately in volts which will generally be, not an
integral number but a numeric with several places of decimals. Then by a single
calculation I find the resistance which must be added to the galvanometer coil, to
give an exact number of divisions of deflection for an integral number of volts. —
When the instrument is to be used to measure a much larger number of volts than
the scale would admit of with the same resistance, I throw in additional resistance,
so calculated as still to give an integral number of divisions of deflections, for an
integral number of volts.-To allow these operations to be performed conveniently
and rapidly, I use a new decimal arrangement of resistance coils consisting of one
or more pairs of tens of resistance coils.-The twenty coils of each pair of ten are
permanently soldered together in series.-The junctions, and the separate ends of
the first and last coils, are connected by twenty one short wires to twenty one
studs fixed on a semicircle or on two adjacent semi-circles.-The working terminals
of the pair of tens are connected with two arms turning round an axis or axes, 80
that one of them may be brought from the centre stud to any number on one side
of it, and the other to any number on the other side of it.-The ten coils on each
side are of equal resistances, and the resistance of each of those on the left side is
ten times that of each on the right. The studs are numbered from 0 to 10, on
each side from the middle stud-Thus for example if the arm on the left is placed
at 7, and the arm on the right at 3, the resistance between the two terminals is
73 times the resistance of one of the coils on the right.
Two such sets of decimal pairs placed in series, with the right hand working
terminal of one pair connected with the left hand working terminal of the other
pair, gives a ready means of making up a resistance of from 1, to 11,110.-For this
purpose the resistance of each of the right hand coils of the left hand pair, should
be exactly ten times the resistance of each of the left hand coils of the right hand
pair.
For a very long range potential meter I place such a series of two pairs of ten,
in a convenient receptacle under lock and key below the galvanometer, with a
permanent connection between one end of the galvanometer coil and one main
terminal of the resistance coils; and with a proper appliance for connecting with
the other end of the galvanometer coil, and the other end of the resistance coils, the
two electrodes leading to points whose difference of potentials is to be tested, and
for readily reversing these connections
The manner in which the details of the potential meter have been carried out
will be learned by reference to Figures 42, 43, 44, and 45, Sheets 21, 22, and 23,

page_text: '
of the accompanying Drawings, which represent the said potential meter
respectively in front elevation, side elevation with the case partly in section and
in plan, Figure 45, representing diagrammatically the manner in which the several
resistance coils are connected together.-The two coils 57, are fixed to the circular
plate, which is secured to the sole plate 7, by the two screws m², working in
slots n', (Figure 44,) thus permitting the adjustment about a vertical axis.-The
system of needles is astatic, consisting of two needles magnetised contrary-ways-
The upper needle o', is carried within the pointer p'-The lower needle q', is
supported in position by a light metal strip 7, which is attached to the pointer p',
and has on its upper end a wide ring 87, to which is attached the lower end of the
supporting fibre t-This ring 87, is situated in a space between the two checks u7,
on the bar -The pin w7, is screwed or fixed into the two checks u, so as
to pass through the axis of the ring 87, when the pointer p', and system of
needles is hanging freely suspended by the fibre -The upper end of the fibre t7,
is attached to one end of a spring x, which is secured by a screw y7, at its other
end to the frame 27-A screw as, serves to depress the free end of the spring 7,
and thus to lower the fibre t, until the whole weight of the pointer and needles is
borne by the pin w'.-The dimensions of the ring 87, are so related to the width of
the space between the checks u, and the diameter of the pin w, that it offers no
hindrance to the motion of the pointer p², throughout its range.
Figure 45, shews diagrammatically the way in which the coils are connected to
the studs 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, of each of the four series.-The terminal d³,
is connected by the plate es, to the arm f8-Thé arm g8, which is insulated from the
arm f, on the central pin, is similarly connected by the plate h³, to the terminal 18,-
A copper bar 78, connects the terminals is, and -The connections between the
terminals, and 18, of the other two series of resistance coils are similar.-Thus
the circuit between the terminals d8, and 18, with the arms as shewn on the
Drawings is through es, to the arm f8, across the stud numbered zero to the arm 98,
and from it by the plate h³, to the terminal i8.-From 8, through the plate 1³, to
the terminal -From k³, the circuit is continued through me, to the arm n³,
across the stud marked zero to the arm o³, and from it by the plate p³, to the
terminal 18-Hence the resistance between the terminals 18, and d³, with the arms
as shewn is appreciably zero.-The resistance between contiguous studs of the
rows passed over by the arm f³, is one unit, by the arm g³, ten units, by the
arm no, one hundred units and by the arm 08, one thousand units.-Thus if the
arms were placed as follows:-f8, on stud 6, 98, on stud 7, ns, on stud 2, and oº,
on stud 9, the resistance between the terminals 18, and d³, would be nine thousand
two hundred and seventy six of the units of the box.-A list, obtained by
calculation from one trial, gives the resistances which must be put in series with
the galvanometer coils j", so as to give integral numbers of volts per division of
deflection for various grades of measurement.-By this means the instrument is
capable of being used to measure great differences of potential.
The two ends of the coils 37, are brought out at 9%, and 78.-The one 7, is
connected to the terminal 18, of the resistance box. The remaining terminal qº, of
the galvanometer and the wire 88, connected with the terminal de; of the resistance
box constitute the terminals which are connected to the electrodes, leading to points
whose difference of potentials is to be tested.
A spirit level t³, is fixed to the sole of the instrument and similar spirit levels are
fitted to all galvanometers constructed according to this Invention, for adjusting the
said instrument to a "dead" level.
As regards this part of my Invention what I claim is :-
First The long range potential galvanometer with its details of resistance coils
connected permanently to it, and with the adjustable mounting of its electro-
magnetic coil or coils to cause the deflections on the two sides of the zero of the
scale, to be equal, with equal currents through the coil in the two directions.
Second-The silk fibre suspension with the ring and pin guard for portability in

page_text: the preceding instrument and in the hereinafter described conductivity meter; and
which is applicable also to other forms of galvanometer and either to a single needle
or to an astatic pair of needles.
To measure currents supplied by the dynamo, I use a galvanometer with two
circular coils of thick copper rod or slip in circuit with one of the mains and a
needle suspended centrally between them.-To regulate to any degree the stability
of the needle in its zero position, I use a fixed electro-magnet in the manner
described in the twentieth part of the Specification filed in pursuance of Letters
Patent granted to me N° 329. A.D. 1858, and represented in Figure 6, of the
Drawings annexed to that Specification I now make the coil of this magnet of fine
german silver wire wound on a single bobbin or pair of bobbins of brass or other
suitable material, and placed between the two thick copper coils, with the magnetic
axis of the fine wire coils as nearly as may be perpendicular to the magnetic axis of
the thick copper coils.-The essential part of this condition is that the vertical
planes containing the lines of electro-magnetic force at the centre of the needle or
system of needles, which for brevity call the "traverse planes' or simply the
traverses," shall be as exactly as possible mutually perpendicular to one another.
To allow adjustment to fulfil this condition, the brass bobbin or bobbins carrying
the fine wire, are capable of a slight motion round the vertical of the suspension of
the needle. I provide also an adjusting magnet by which when the instrument is
placed for use in any locality, the magnetic force on the needles whether due to the
earth, or to fixed magnets in the neighbourhood may be readily counterbalanced,
with sufficient accuracy to render its effect insensible in the measurements made by
the instrument.
"
"
One simple form of adjusting magnet is that of a horizontal bar, supported by
means of a split tube on a vertical shaft passing through a hole in its middle.-The
axis of the shaft is coaxal with the axis about which the needle or system of
needles moves. A clamping nut on the split tube serves to clamp the magnet in
any position-The magnet is thus capable of two motions; one of translation in a
vertical direction, and one of rotation about a vertical axis.-In practice, however,
I prefer to attain the desired object by making the system of needles astetic.-
When this has been done, in any place the azimuthal adjustment of the fine wire coil
is made once for all as follows:-A current from any convenient source is kept running
constantly through the fine wire coil or coils; equal currents in opposite directions
are sent through the circuit of the thick wire coils, and the brass bobbin is
azimuthally adjusted until the deflections are found to be equal on the two sides
of the position, in which the needle or system of needles rests when the current
through the thick wire coils is annulled and that through the fine wire coil or coils
is kept flowing.
The instrument has also an adjustment of the graduated circular scale, by which
its zero is brought exactly to the position in which the pointer rests under the
influence of the current through the fine wire coil or coils when there is no current
through the thick wire coils. When the instrument is to be used through a wider
range than admits of convenient measurement with one grade of sensibility,
different grades are given by resistance coils conveniently fixed in the base of the
instrument and arranged to give very readily one or other of a small number of
definite resistances exactly suited for each grade of sensibility to be provided for.
It is generally most convenient to use the difference of potentials between the
two mains, for producing the current through the fine wire coil or coils.-As long
as the difference of potentials remains constant, the reading of the galvanometer
(supposed to be graduated according to tangents) is simply proportional to the
strength of the current, but if the electro-motive force varies the readings will be
proportional to the reciprocals of the resistances, that is to the total conductivity
in the circuit through the thick wire coils and the mains.-This will, in a system
of incandescent lighting, be very nearly in simple proportion to the number of
lamps of one type on the circuit at any time, and accordingly I prefer in many
cases to adjust the sensibility of the instrument, by giving the proper resistances

page_text: to the fine wire controlling coil or coils themselves in the construction of the
instrument, or by adding the proper amount of resistance to them, by means of the
resistance coils in the base of the instrument so that the number of lamps on the
circuit at any one time may be read off with great ease without any troublesome
calculation, from the number shewn by the pointer on the circular scale.
An instrument fulfilling the conditions herein before described I have termed a
"conductivity meter," because, while suitable for use in measuring the current
flowing in a circuit, its parts and adjustment render it more convenient as a
measurer of conductivity.-Figures 46, 47, and 48, Sheets 24 and 25 of the
accompanying Drawings represent the arrangement of the essential details,
respectively in front elevation, side elevation and in plan.-The instrument shewn
is similar to the potential meter described with reference to Figures 42, 43, 44,
and 45, with the addition of the thick coils u.-These consist each of one turn of
heavy strip copper, and are placed at equal distances on each side of the vertical
axis about which the system of needles turns, and with a common axis coaxal
with that of the lower needle when the pointer is properly adjusted to its
zero. The coils u³, are so connected in series, that the current passing through by
means of the terminals w³, circulates in one direction in the one coil, and in an
opposite direction in the other coil.-The terminals of the fine wire coils are shown
at ³.
In some cases I use two pairs of thick wire coils, the second pair consisting of
two smaller coils coaxal with the first pair, but placed at a greater distance on
each side of the vertical through the needle. The second pair are independent of
the first pair and the electrodes are brought out at a different position.-By this
means I render one instrument capable of measuring, from very large to moderately
small amounts of current, or when used as a lamp meter amounts of conductivity
within a considerable range.
As regards this part of my Invention what I claim is :-
The conductivity meter with its adjustment adjusting the traverses of the coils
to exact perpendicularity, and an astatic pair of needles to avoid disturbance from
terrestrial or other magnetic force, or alternatively of a fixed magnet to counteract
such force as herein before described with reference to Figures 46, to 48 (inclusive)
of the accompanying Drawings.
In Witness Whereof I, the said Sir William Thomson have hereunto set my
hand and seal this twenty-fifth. day. of September in the year of Our Lord One
thousand eight hundred and eighty-three.
TYTTITE MEAWAY