IMPROVEMENTS IN L APPARATUS FOR MEASURING ELECTRICITY
Year: 1883

page_text: LETTERS PATENT to Joseph Devonport Finney Andrews of Glasgow in the
County of Lanark North Britain for an Invention of "IMPROVEMENTS IN
L
APPARATUS FOR MEASURING ELECTRICITY.”
PROVISIONAL SPECIFICATION left by the said Joseph Devonport Finney
Andrews at the Office of the Commissioners of Patents on the 18th May
1883.
JOSEPH DEVONPORT FINNEY ANDREWS of Glasgow in the County of Lanark
North Britain "IMPROVEMENTS IN APPARATUS FOR MEASURING ELECTRICITY"
An electroscope according to my invention consists of a vertical solenoid, the
iron core of which is enlarged at its lower end where it is immersed in mercury.
A thread attached to the top of the core passes several times round a spindle of
small diameter and carries a counterweight. On the spindle is fixed an index in
front of a graduated dial. When a current of electricity passes through the coil of
the solenoid, the core is attracted upwards and the spindle revolves, carrying the
As
index more or less round according to the strength of the electrical current.
the index may make several revolutions, a scale may be applied to the descending
counterweight to indicate the number of revolutions made by the index. Or the
dial may be graduated in a volute or spiral line, and the index may be made to
slide radially as it revolves, so that its point follows the volute curve, by attaching
to it a thread winding on a stationary stud or by providing it with a lateral rack
gearing with a stationary pinion.
In applying a voltameter to ascertain the quantity of electricity passing through
it, I collect the gases generated by the electrical decomposition of water in a close
vessel charged with liquid and communicating by a pipe at its bottom with a tank
provided with a float and index. The rise of liquid in the tank as indicated by
the float, being dependent on the volume of the gases generated, serves as an
indication of the amount of electricity passed through the voltameter. According
to a modifiéd form of the apparatus, the gases may be collected in the bell of a
gasometer floating in liquid, the ascent of the bell being measured by an index
14.
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page_text: connected to it. For fine subdivision, the circumference of the bell may be graduated
in a helical line, so that its ascent can be very accurately determined by ascertaining
the point where the stationary edge of the gasometer vessel intersects the helical
line on the bell. Instead of measuring the volume of gases generated by the
voltameter, the pressure may be measured by the rise of a mercurial column. When
it is required to measure by the voltameter the quantity of electricity passing
through it during a considerable time, I adopt the following arrangement. I
connect the vessel in which the decomposition takes place to a mercury cup, and
in the decomposition vessel at its upper part I place a wire or strip of platinum
forming part of a by-pass circuit. The generation of gases in the voltameter
vessel causes the mercury to rise in the cup connected to it, until contact is made
with a wire so as to close the by-pass circuit. The wire or strip of platinum,
becoming heated by the by-pass current, ignites the gases, and as the products of
combustion condense, the mercury descends breaking the by-pass circuit. In the
by-pass circuit is arranged a solenoid having its core connected to a counter which
indicates and registers the number of times that the decomposition and recom-
position take place, and, thus serves to. measure the amount of electricity that
passes through the voltameter.
Electricity may be measured by the flow of mercury from one vessel to another
in the following manner :-I provide two vessels containing mercury, the one
situated above the other, with a beam pivotted between them. To one end of the
beam is linked the core of a solenoid, this core having its lower end enlarged and
immersed in the mercury in the lower vessel. To the other end of the beam is
linked a cup having an overflow pipe leading to the lower vessel, and having
inserted in it one limb of a siphon, the other limb of which is immersed in the
mercury in the upper vessel. When a current of electricity passes through the
solenoid coil, the core is attracted upwards more or less according to the strength
of the current, and thus the cup at the opposite end of the beam is proportionally
lowered, so that mercury flows into it through the siphon from the upper vessel,
and the overflow passes into the lower vessel. The total flow of mercury from the
upper to the lower vessel is a measure of the electricity. In order to provide for
continuous action, I employ the following modification of the apparatus. I mount
the beam and the solenoid on a float on the mercury in one vessel, and to the end
of the beam opposite to that linked to the solenoid core I attach a siphon having
one limb dipping into the mercury and the other limb extending downwards.
outside the vessel and terminating with a turned up end above a stationary cup.
This cup is connected by a flexible or jointed pipe with a second or moveable cup
linked to a beam or lever to which is also linked the core of a second solenoid
having its coil in a by-pass circuit. The second solenoid and its beam are
mounted on a float in a second mercury vessel communicating by a pipe with the
first vessel. The action of the apparatus is as follows. The first solenoid being
excited by a current of electricity attracts its core upwards, and the siphon at the
opposite end of the beam being thus lowered, mercury flows by it into the
stationary cup and thence, by the flexible or jointed pipe, into the moveable cup
which is then at a lower level. When the mercury rises to a certain height in the
moveable cup, it makes contact with a wire which closes the by-pass circuit.
The second solenoid, being thus excited, attracts its core upwards raising the
lever and moveable cup to such a level that a siphon communicating with
the second mercury vessel, draws the mercury from the moveable cup into the
second vessel from which it flows back to the first vessel. The moveable cup
having thus discharged its contents, the by-pass circuit is reopened, and the cup
again descends, so that the cycle of operations is repeated. The number of
movements registered by a counter serves to indicate the electricity that has
passed through the solenoid coils. According to a modified form of the apparatus,
two mercury cups are suspended from opposite ends of a beam provided with a
tumbling weight, and are connected to a second beam carrying an armature and
contact key. A siphon with the ends of its limbs turned up is placed so
that

page_text: one end is in each of the two cups, and contact wires are arranged so that
contact is made and broken according as the mercury rises or falls in each cup,
these contacts being respectively in the circuits of two electromagnets situated
on opposite sides of the armature. When one of these electromagnets is excited,
it attracts the armature, and one of the two cups being thus at a higher level
than the other, mercury flows through the siphon from the higher to the lower
until contact is made with the wire in the lower cup, the contact in the upper
cup being broken. The other electromagnet being now excited attracts the
armature causing the higher cup to descend and the lower cup to ascend, where-
upon the flow of the mercury is reversed and the action is repeated. The number
of alternations registered by a counter indicates the amount of electricity passed
through the apparatus, but in order that the alternations may succeed each other
more or less rapidly, according to the greater or less force of the electricity,
I mount the siphon on a lever linked to the core of a solenoid having its coil in the
electrical circuit, so that the greater the electrical force the more deeply is the
siphon immersed in the mercury in the cups.
Instead of employing the flow of mercury for indicating," as above described,
the passage of electricity, I employ a mechanical arrangement of the following
kind. I cause a disc or cone to revolve by clockwork at a uniform speed
controlled by a pendulum or other suitable regulator, and I mount parallel to
the face of this disc or cone a second eccentric disc or opposite cone, with a small
wheel having a rounded edge pressed between both surfaces so as to have good
frictional contact with them. This wheel is caused to slide along an axis parallel
to the two faces by a connection with a solenoid core, so that its radial distance
from the centres of the two discs or its distance from the apices of the two
cones is determined by the force of the electrical current exciting the solenoid.
The velocity thus imparted to the second disc or cone, as registered by a counter
worked by it, indicates the electrical force. Instead of working the second cone
by the frictional contact of a wheel it may be worked by a band passing round
both cones, the position of the band relatively to the apices of the two cones being
determined by the solenoid.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Joseph Devonport Finney Andrews in the Great Seal Patent
Office on the 16th November 1883.
JOSEPH DEVONPORT FINNEY ANDREWS of Glasgow in the County of Lanark,
North Britain "IMPROVEMENTS IN APPARATUS FOR MEASURING ELECTRICITY
"
An electroscope according to my invention is shewn in vertical section at Fig. 1
of the accompanying Drawings. It consists of a vertical solenoid a, the iron core c
of which is enlarged at its lower end c¹ where it is immersed in mercury d.
A thread attached to the top of the core passes several times round a spindle b of
small diameter and carries a counterweight h. On the spindle is fixed an index i
in front of a graduated dial j. When a current of electricity passes through the
coil of the solenoid a, the core c is attracted upwards and the spindle b revolves,
carrying the index i more or less round according to the strength of the electrical
current. As the index i may make several revolutions, a scale may be applied to
the descending counterweight h to indicate the number of revolutions made by the
index. Or the dial may be graduated in a volute or spiral line and a pointer may
be put on the counterweight to indicate which branch of the volute is to be read
for any position of the index i.
Electricity may be measured by the flow of mercury from one vessel to another
in the manner shewn in Fig. 2. I provide two vessels containing mercury the
one a situated above the other b, with a beam e pivotted between them. To one
end of the beam e is linked the core g of a solenoid h, this core having its lower
end enlarged and immersed in the mercury in the lower vessel b. To the other end
of the beam e is linked a cup d having an overflow pipe i leading to the lower
vessel b, and having inserted in it one limb of a siphon c, the other limb of which
is immersed in the mercury in the upper vessel a.
The cup
kept vertical by a
weight f bung below it. When a current of electricity passes through the solenoid
coil h, the core g is attracted upwards more or less according to the strength of the
current and thus the cup d at the opposite end of the beam is proportionally
lowered, so that mercury flows into it through the siphon c from the upper vessel a
and the overflow passes into the lower vessel b. The total flow of mercury from.
the upper to the lower vessel is a measure of the electricity. In order to provide
for continuous action, I employ a modification of the apparatus such as is shewn
at Fig. 3. I mount the beam e and the solenoid b on a float h on the mercury in
the one vessel a, and to the end of the beam opposite to that linked to the solenoid
core I attach the siphon c having one limb dipping into the mercury in a and the
other limb extending downwards outside the vessel into a stationary cup d. This
cup is connected by a flexible or jointed pipe with a second or moveable cup m
linked to a beam or lever k to which is also linked the core of a second solenoid
having its coil b¹ in a by-pass circuit. The action of the apparatus is as follows.
The first solenoid being excited by a current of electricity attracts its core b
upwards, and the siphon c at the opposite end of the beam e being thus lowered,
mercury flows by it into the stationary cup d, and thence, by the flexible or jointed
pipe into the moveable cup m which is then at a lower level. When the mercury
rises to a certain height in the moveable cup m it makes contact with a wire g,
which closes the by-pass circuit. The second solenoid 6 being thus excited

page_text: attracts its core downwards raising the moveable cup m to such a level as indicated
at m', that a siphon c¹ communicating with the mercury vessel a draws the
mercury from the moveable cup m into the vessel a. The moveable cup m
having thus discharged its contents, the by-pass circuit is re-opened by the
separation of the mercury from and the cup m again descends, so that the
cycle of operations is repeated. The number of movements registered by a
counter serves to indicate the electricity that has passed through the solenoid
coils. According to a modified form of the apparatus shewn at Fig 4, two
mercury cups a and b are suspended from opposite ends of a beam c provided
with a tumbling weight k, and are connected to a second beam & carrying an
armature h and contact key j. A siphon e with the ends of its limbs turned up
is placed so that one end is in each of the two cups a and b and contact wires
are arranged so that contact is made and broken according as the mercury rises
or falls in each cup, these contacts being respectively-in the circuits of two
electro-magnets g g' situated on opposite sides of the armature h. When one of
these electro-magnets is excited, it attracts the armature, and one of the two
cups being thus raised to a higher level than the other, mercury flows through
the siphon e from the higher to the lower until contact is made with the wire in
the lower cup, the contact in the upper cup being broken. The other electro-
magnet being now,excited attracts the armature h, causing the higher cup to
descend and the lower cup to ascend, whereupon the flow of the mercury is
reversed and the action is repeated. The number of alternations registered by a
counter indicates the amount of electricity passed through the apparatus, but in
order that the alternations may succeed each other more or less rapidly, according
to the greater or less force of the electricity, I mount the siphon e on the end of
a lever linked to the core of a solenoid having its coil in the electrical circuit as
the siphon c in Fig. 3. so that the greater the electrical force the more deeply is
the siphon immersed in the mercury in the cups..
Instead of employing the flow of mercury for indicating, as above described, the
passage of electricity, I employ a mechanical arrangement of the kind shewn in
Fig 5. I cause a disc A to revolve by clockwork B at a uniform speed controlled
by a pendulum C or other suitable regulator, and I mount parallel to the face of
this disc A a second disc D having its axis pressed by a spring E, with a small
wheel F having a rounded edge pressed between the surfaces of the discs A and D,
so as to have good frictional contact with them. This wheel F is caused to slide
along an axis f parallel to the faces of the discs by a swivel connection h with a
lever H to which is linked a solenoid core G, so that the radial distance of F from
the centres of the two discs is determined by the force of the electrical current
exciting the solenoid. The velocity thus imparted to the wheel F as registered by
a counter worked by it, indicates the electrical force. The axis ƒ may be fitted to
slide through a pinion k which turns with it and gives motion to the gearing of a
counter arranged in K.
Having thus described the nature of my invention and in what manner the
same is to be performed, I claim :-
First. The construction of electroscope, substantially as herein described with
reference to Fig. 1.
Second. The construction of apparatus, substantially as described with reference
to Fig. 2, for measuring electricity by the flow of mercury from one vessel to
another.
Third. The modified construction of apparatus for measuring electricity by the
flow of mercury, and for automatically replacing the mercury, substantially as
described with reference to Fig. 3.
Fourth. The modified construction of apparatus for measuring electricity by the
flow of mercury between two vessels alternately, substantially as described with
reference to Fig. 4.
Fifth. The construction of apparatus for measuring electricity by the velocity

page_text: imparted to a wheel which is pressed between two revolving discs and has its
radial distance from the axis of the discs determined by the attraction of a solenoid
core, substantially as herein described with reference to Fig. 5.
In Witness whereof I the said Joseph Devonport Finney Andrews have
hereunto set my hand and seal this Thirteenth day of November in the year of
our Lord One thousand eight hundred and eighty-three.
TD T ANDDEN
Ga