IMPROVEMENTS IN APPARATUS FOR REGULATING AND CONTROLLING ELECTRICAL CURRENTS
Year: 1882

page_text: LETTERS PATENT to Percy Ruskin Allen of Victoria Works Belvedere Road
Lambeth in the County of Surrey for an Invention of "IMPROVEMENTS IN
APPARATUS FOR REGULATING AND CONTROLLING ELECTRICAL CURRENTS
33
1:0:
PROVISIONAL SPECIFICATION left by the said Percy, Ruskin, Allen at the
Office of the Commissioners of Patents on the 13th November 1882. རྞ་
PERCY RUSKIN ALLEN of Victoria Works Belvedere Road Lambeth in the
County of Surrey "IMPROVEMENTS IN APPARATUS FOR REGULATING AND
CONTROLLING ELECTRICAL CURRENTS
"
:
My Invention relates to improvements in variable resistances used in conjunction
with electric lighting apparatus. One part of my Invention relates to an improve-
ment in hand regulators for varying the resistance of carbon plates or blocks and
consists in the use of a differential screw to regulate the amount of pressure on the
blocks or plates, the use of this differential screw enabling a large amount of motion
to be given to the hand wheel for a small amount of travel to the plate pressing
the blocks, thus a fine adjustment can be obtained, without any great attention
being paid to the hand wheel and the motion of the hand wheel itself having a
considerable range enables the degree of compression to be read off direct by means
of a graduated scale at the side
I sometimes arrange my differential screws in the following manner. I make the
inner screw attached to the block, that compresses the carbons so that it can be
locked with the movement of a small lever or catch to the block, and forms for the
time a solid portion of the block.
The outer screw has also an arrangement of this sort by which it can be locked.
to the inner screw so that the inner screw would rotate with it. If the outer
screw be unclamped from the inner screw and the inner screw fixed to the block,
the total movement of the block is due to the difference of the pitch of the screws,
thus if the outer pitch equal 10th of an inch and the inner 1th, one revolution of
the outer would cause the block to move 100th of an inch but if now the inner
screw be free to move in the block that is clamped with; the outer screw it is

page_text: evident that one revolution of the outer screw will cause the block to move 11 th of
an inch. There are several ways in which this may be accomplished for example,
the inner screw may have a groove turned on it, where it enters the block, and is
secured there by an eccentric pin which enters the groove.
When the handle is
turned in one position it locks the screw into the block and when placed in the
outer position it permits it to turn. The outer screw has a clamp attached to the
hand wheel which may be thrown in to engage keyways, or its equivalent on
the inner screw so that when desired, the outer and inner screws may be locked
together. Instead of causing the fork to enter the keyway, the outer screw may be
caused to grip the inner screw by causing it to jam apart a thin nut which rotates
with the Hand wheel and thus have the same effect as a small lock nut or it may
compress a portion of the nut in the inner screw and thus cause it to grip.
Instead of locking the inner screw to the block it may be made so that it is.
always free to move in the block but it is prevented from turning when desired by
means of a movable feather or feathers entering key-ways, cut longitudinally down
the screw
« arc
"
In combination with this regulator I employ a switch which may be automatic
or partially automatic for making and breaking the circuit when the Carbons are
separated to the full degree thus preventing the formation of a destructive
between the Carbon plates themselves. The switch may be so arranged that when
the hand wheel has descended a certain distance it releases the spring tongue of
the switch and flys over and breaks contact the range of movement of the tongue
being such that it prevents an arc" being formed between the tongue and
button If desired the switch may be so arranged that when it flies over, it locks
the hand wheel and prevents it being turned back until the switch has been
replaced upon the contact button by hand thus preventing the carbons being
compressed before the circuit through them is completed
"
In another arrangement the switch is so contrived that the motion of the hand
wheel in one direction breaks the circuit suddenly and when it is turned again in
the other direction completes the circuit again
The degree of the compression of the carbons may be registered in various ways.
A finger passing over a dial and attached to the hand wheel or moveable plate may
be used
•
It is a well known fact that the electrical resistance of carbon diminishes with
an increase of temperature and to compensate for this, I construct the frame of my
box containing the carbon blocks or plates of metal of such quality and section
that as the Carbons heat through the continued passage of a current through them,
the box expands in a certain definite proportion and so slightly separates the
Carbons thus keeping the resistance constant or the rod or screw by which the
Carbons are compressed may be caused to expand or compensate in a similar
manner.
I prefer to construct the box so that the strain due to the compression of the
carbons is entirely carried by the central screw which may be placed between the
blocks of carbon and thus receive a portion of the heat radiated from each of the
piles of carbon or the plate which carries the nut or point where the pressure is
applied to the Carbons may be connected to the plate against which the other end
of the piles of carbon rest, by means of bolts or screws so arranged that all receive
approximately the same amount of heat radiated from the piles of carbon, or the
plates may be simply connected with tubes or metallic casings of such a composition
and section that they expand in the proper ratio to the heat of the carbons. If this
arrangement be suitably carried out the resistance is kept almost constant.
combination with Hand regulators of this sort I also use a variable metallic Resistance
placed either in parallel arc or in series with a variable carbon resistance and arranged
so that when the carbon resistance is varied by compression a corresponding
definite amount of metallic Resistance is cut out or short circuited so that
whatever the resistance may be varied to the compensating ratio between the metal
and the carbon remains the same. This may be accomplished in various ways either
In

page_text: by causing a finger or contact tongue to move over studs or contact pieces on the
wire resistance as the carbon is compressed or released or by causing the metallic
spiral or resistance wire to dip more or less into mercury as the carbon is
compressed or released. The spiral may be arranged some distance from the piles
of Carbon and be solely heated by the passage of the current through it or it may
be placed in close proximity to the carbons so that it receives some of its heat by
radiation from the piles of carbon as well as by the passage of the current
through itself. The diminution of the resistance of carbon may, if desired be
compensated for by means of this variable metallic resistance used by itself or in
combination with the expanding metallic case already referred to I may also
employ an automatic variable carbon resistance for automatically controlling the
current produced by dynamo-electric machines. This has more especially reference
to machines used for incandescent lighting in which the magnets are placed on a
shunt to the main circuit but by slight alterations it may also be used with
machines in which the magnets are in the main circuit or are independently
excited. In this regulator the piles of carbons are compressed or released by means
of a screw which may be plain or of a differential form already described in the
Hand Regulator. This screw has attached to it a small bevel or mitre wheel or it
may be a friction wheel. The bevel or mitre or friction wheel is caused to gear
with two others which are caused to rotate by a spindle driven by means of a gut
or cord off the shaft of the dynamo machine or from any other convenient shaft or
if desired an independent motor such as a Grisgain or Trouré motor or any
appropriate electro motor but I prefer to drive it from the shaft of the machine as
being most simple and convenient The wheels may be arranged so that they run
loose on the shaft and only revolve with it when they are engaged by a small
clutch which turns with the shaft but is moved lengthways on the shaft by means
of an electro magnet or magnets acting on an armature attached to the clutch
lever When these magnets are not in action the armature remains in a central
position and the clutch does not engage with either of the wheels therefore the
screw is not turned and the resistance in the carbon piles remains unaltered
When the current is sent into either one or other of the magnets the keeper is
attracted and the clutch caused to engage with either of the other wheels, the
screw is screwed up, or down and more or less resistance placed in the carbon
circuit.
When this apparatus is used for regulating lamps for incandescent machines the
variations in the electro motive force as the lamps are turned on or off is measured
by means of a solenoid wound with a considerable amount of fine wire and placed
so as to connect the positive and negative leads of the circuit and preferably at a
point in the centre of the distribution system. The core of this solenoid is attached
to a lever which makes contact with one or other of two stops as the electro motive
force between the two main conductors varies and it has a retractile spring so
adjusted that at a certain determined position the contact lever remains free
between the stops without being in contact with either. In this case the magnets
of the regulator are not acted upon and the carbon resistance remains unaltered
but should any lamps be turned off the electro motive force increases somewhat,
more current at once flows round the solenoids, the core is sucked further in and a
contact is made with one of the stops and by this means the current is directed
round one of the magnets of the regulator causing the clutch to engage with one
of the bevel or mitre or friction wheels which actuates the screw and causes the
carbons to be less closely pressed together thus increasing the resistance and causing
less current to circulate round the field magnets thus reducing the electro motive
force at the terminals of the machine. When the electro motive force has fallen to
the normal level the contact lever of the regulating solenoid rises off the stop, the
magnet ceases to act, the clutch is thrown out and the resistance remains stationary
until it is again called upon to adapt itself to another alteration in the number and
power of the lamps. When instead of turning lamps off, lamps are turned on
exactly the reverse takes place, the retractile spring pulls the core further up into

page_text: the solenoid and,makes a contact with the other stop,this causes the other magnet
in the regulator to become active and to pull the clutch into gear with the other
wheel so, that the carbon resistance is diminished and the electro motive force
attains its normal pitch. Instead of a solenoid I prefer sometimes to employ a
measuring instrument in which two coils of wire are attracted to one another like
a Siemens dynamometer the moveable coil carrying a contact wire which dips into
mercury cups and so directs the current or I sometimes employ a voltameter with
a bent contact wire attached to the lever which dips alternately into the mercury
cups and so directs the current. The current which actuates the magnets is
arranged as a shunt to the main circuit and the magnets are preferably wound
with very fine wire so that only a small portion of the current flows round them
In some cases I prefer to use another. resistance equal to one of the magnets so that
when the apparatus is not in action the shunt current flows through the resistance
instead of the controlling magnet. When the indicating solenoid acts, it turns the
currents from this resistance into one or other of the magnets. The object of this
is to prevent the main current being affected by suddenly having the shunt open
through the magnets
In some cases instead of using toothed wheels, I employ friction wheels and
make the wheel which controls the regulating screw of hard wood or compressed
paper or of metal covered with leather or india rubber and actuate this wheel by
means of a double flanged pulley driven by a band off a motor or by a cord from
the engine shaft as already described. This double Banged pulley may be arranged
so that it acts as an armature to the controlling magnet so that when the
current is sent through the magnet it forces the revolving pulley into contact with
the friction wheel and thus actuates the screw, it may be driven by a motor as
already described.
:
In cases where I require a finer adjustment of the carbons, I arrange the screws
to act not directly on the carbons but on a wedge which varies the compression of
the carbons. The piles of carbons may be placed vertically horizontally or in any
desired position they may be arranged either in "multiple arc or in series and I
attach binding screws to each. pile so that they may be .coupled up to suit the
various requirements of the machine
.
Similar arrangements for compensating for the changes in resistance due to the
increase or decrease of temperature as already described in connection with the
hand regulator may also be employed in the automatic regulator, but in this case
it is not so necessary, because the variations in the resistance due to the variations
of temperature are compensated for automatically

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Percy Ruskin Allen in the Great, Seal Patent Office on the
12th May 1883.
:
PERCY RUSKIN ALLEN of Victoria Works Belvedere Road Lambeth in the
County of Surrey "IMPROVEMENTS IN APPARATUS FOR REGULATING AND
CONTROLLING ELECTRICAL CURRENTS."
My said Invention relates to improvements in variable resistances used in
conjunction with electric lighting apparatus. One part of my Invention has
reference to Improvements in band regulators for varying the resistance of carbon
plates or blocks and consists in the use of a differential screw to regulate the amount
of pressure on the blocks or plates the use of differential screws enabling a large
amount of motion to be given to the hand wheel for a small amount of travel to
the plate pressing the blocks thus a fine adjustment can be obtained without any
great attention being paid to the hand wheel and the motion of the hand wheel
itself having a considerable range enables the degree of compression to be read off
direct by means of a graduated scale-I sometimes employ in combination with
differential screws means for causing them to rotate together for the purpose of
obtaining a more rapid action when required.
1
:
According to one modification the outer screw has an arrangement of lever or
catch by which it can be locked to the inner screw so that the inner screw would
rotate with it, and the outer screw may be unclamped from the inner screw and the
inner screw fixed to the block. There are several ways in which this may be
accomplished for example the inner screw may have a groove where it enters the
block and is secured therein by an eccentric pin which enters the groove-When
the operating handle or wheel with which the screw is provided is turned in one
position it locks the screw into the block and when turned in the opposite position
it permits it to turn-The outer screw has a clamp attached to the hand wheel
which may be thrown in, to engage keyways on the inner screw so that when
desired the outer and inner screws may be locked together-Instead of causing
the clamp to enter the keyways the outer screw may be caused to grip the inner
screw by causing it to jam apart a thin nut which rotates with the hand wheel
and thus have the same effect as a small lock nut or it may compress a portion
of the nut in the inner screw and thus cause it to grip.
"
Instead of fixing the inner screw to the block it may be fitted so as to be free.
to move in the block but may be prevented from turning when desired by means
of a clamp and a movable feather or feathers entering key-ways cut longitudinally
down the screw.
.3
In combination with this regulator I employ a switch which may be automatic
or partly automatic for making and breaking the circuit when the carbons are;
separated to the full degree thus preventing the formation of a destructive "arc
between the Carbon plates themselves.
".
"
The switch may be so arranged that when the hand wheel has descended a
certain distance it releases the spring tongue of the switch and flys over and
breaks contact the range of movement of the tongue being such that it prevents an
are being formed between the tongue and button If desired the switch may be
so arranged that when it flys over it locks the hand wheel and prevents it being:
turned back until the switch has been replaced upon the contact button by hand
thus preventing the carbons being compressed. before the circuit through them is
completed
i. :..9

page_text: In another arrangement the switch is so contrived that the motion of the hand
wheel in one direction breaks the circuit suddenly and when it is further turned
completes the circuit again.
The degree of the compression of the carbons may be registered in various
ways A finger passing over a dial and attached to the hand wheel or moveable
plate may be used.
+
It is a well known fact that the electrical resistance of carbon diminishes with an
increase of temperature and to compensate for this-I construct the frame of my
box (containing the carbon blocks or plates,) of metal of such quality and section that
as the carbons heat through the continued passage of a current through them the
box expands in a certain definite proportion and so slightly separates the carbons
thus keeping the resistance constant or the rod or screw by which the carbons are
compressed may be caused to expand to compensate in a similar manner.
I prefer to construct the box so that the strain due to the compression of the
carbons is entirely carried by the central screw which may be placed between the
blocks of carbon and thus receive a portion of the heat radiated from each of
the piles of carbon or the plate which carries the nut or point where the pressure is
applied to the carbons may be connected to the plate against which the other end
of the piles of carbon rest by means of bolts or screws so arranged that all receive
approximately the same amount of heat radiated from the piles of carbon or the
plates may be simply connected with tubes or metallic casings of such a composition
and section that they expand in the proper ratio to the heat of the carbons—If
this arrangement be suitably carried out the resistance is kept almost constant―
In combination with hand regulators of this sort I also use a variable metallic
resistance placed either in parallel arc or in series with a variable carbon resistance
and arranged so that when the carbon resistance is varied by compression a corre-
sponding definite amount of metallic resistance is cut out or short circuited so that
whatever the resistance may be varied to, the compensating ratio between the metal
and the carbon, remains the same-This may be accomplished in various ways either.
by causing a finger or contact tongue to move over studs or contact pieces on the
wire resistance as the carbon is compressed or released or by causing the metallic
spiral or resistance wire to dip more or less into mercury as the carbon is compressed
or released-The spiral may be arranged some distance from the piles of carbon
and be solely beated by the passage of the current through it or it may be placed
in close proximity to the carbons so that it receives some of its heat by radiation
from the piles of carbon as well as by the passage of the current through itself
The diminution of the resistance of carbon may if desired be compensated for by
means of this variable metallic resistance used by itself or in combination with the
expanding metallic case already referred to-According to another modification I
may employ an automatic variable carbon resistance for automatically controlling
the current produced by dynamo-electric machines. This has more especially
reference to machines used for incandescent lighting in which the magnets are
placed on a shunt to the main circuit but by slight alterations it may also be used
with machines in which the magnets are in the main circuit or are independently
excited.
In this regulator the piles of carbon are compressed or released by means of a
screw which may be plain or of the differential form already described in the hand
regulator. This screw has attached to it a small bevel or mitre or it may be a
friction wheel. This bevel or mitre or friction wheel is caused to gear with two
others which are caused to rotate on a spindle driven by means of a gut or cord off
the shaft of the dynamo machine or from any other convenient shaft or if desired
an independent motor such as a Griscoin or Trouré motor or any other appropriate
electro motor but I prefer to drive it from the shaft of the machine as being most
simple and convenient. The wheels may be arranged so that they run loose on
the shaft and only revolve with it when they are engaged by a clutch which
turns with the shaft and may be moved lengthways thereon by means of an
electro magnet or magnets acting on an armature attached to the clutch lever-

page_text: When these magnets are not in action the armature remains in a central position
and the clutch does not engage with either of the wheels therefore the screw is not
turned and the resistance in the carbon piles remains unaltered-When the current
is sent into either one or other of the magnets the keeper is attracted and the clutch
caused to engage with either of the other wheels the screw is screwed up or down
and more or less resistance placed in the carbon circuit.
When this apparatus is used for regulating lamps for incandescent machines the
variations in the electro motive force as the lamps are turned on or off is measured
by means of a solenoid wound with a considerable amount of fine wire and placed
so as to connect the positive and negative leads of the circuit and preferably at a
point in the centre of the distribution system The core of this solenoid is attached
to a lever which makes contact with one or other of two stops as the electro
motive force between the two main conductors varies and it has a retractile spring
so adjusted that at a certain determined position the contact lever remains free
between the stops without being in contact with either. In this case the magnets
of the regulator are not acted upon and the carbon resistance remains unaltered
but should any lamps be turned off the electro motive force increases somewhat,
more current at once flows round the solenoid, the core is sucked further in and a
contact is made with one of the stops and by this means the current is directed.
round one of the magnets of the regulator causing the clutch to engage with one
of the bevel or mitre or friction wheels which actuates the screw and causes the
carbons to be less closely pressed together thus increasing the resistance and
causing less current to circulate round the field magnets thus reducing the electro
motive force at the terminals of the machine-When the electro motive force has
fallen to the normal level the contact lever of the regulating solenoid rises off the
stop, the magnet ceases to act, the clutch is thrown out and the resistance remains.
stationary until it is again called upon to adapt itself to another alteration in the
number and power of the lamps-When instead of turning lamps off lamps are
turned on exactly the reverse takes place, the retractile spring pulls the core
further up into the solenoid and makes a contact with the other stop, this causes
the other magnet in the regulator to become active and to pull the clutch into gear
with the other wheel so that the carbon resistance is diminished and the electro
motive force attains its normal pitch. Instead of a solenoid I prefer sometimes to
employ a measuring instrument in which two coils of wire are attached to one
another like a Siemens Dynamometer the moveable coil carrying a contact wire
which dips into inercury cups and so directs the current or I sometimes employ a
voltameter with a bent contact wire attached to the lever which dips alternately
in to the mercury cups and so directs the current-The current which actuates the
magnets is arranged as a shunt to the main circuit and the magnets are preferably
wound with very fine wire so that only a very small portion of the current flows
round them In some cases I prefer to use another resistance equal to one of the
magnets so that when the apparatus is not in action the shunt current flows
through the resistance instead of the controlling magnet-When the indicating
solenoid acts, it turns the currents from this resistance into one or other of the
magnets-The object of this is to prevent the main current being affected by.
suddenly having the shunt open through the magnets
In some cases instead of using toothed wheels I employ friction wheels and
make the wheel which controls the regulating screw of hard wood or compressed
paper.or of metal covered with leather or india rubber and actuate this wheel by
ineans of a double flanged pulley driven by a band off a motor by a cord from the
engine shaft as already described This double flanged pulley may be arranged so
that it acts as an armature to the controlling magnet so that when the current is
sent through the magnet it forces the revolving pulley into contact with the
friction wheel and thus actuates the screw
In cases where I require a finer adjustment of the carbons I arrange the screws
to act not directly on the carbons but on a wedge which varies the compression of
the carbons-The piles of carbons may be placed vertically horizontally or in any

page_text: "
desired position they may be arranged either in "multiple arc or in "series" and
I attach binding screws to each pile so that they may be coupled up to suit the
various requirements of the machine
Similar arrangements for compensating for the changes in resistance due to the
increase or decrease of temperature as already described in connection with the hand
regulator may also be employed in the automatic regulator but in this case it is
not so necessary because the variations in the resistance due to the variation of
temperature are compensated for automatically.
And in order that my said Invention may be fully understood I shall now
proceed more particularly to describe the same and for that purpose shall refer to
the several figures in the annexed sheets of drawings the same letters of reference
indicating corresponding parts in all the corresponding Figures
Fig 1. of my. Drawings represents in longitudinal section and Fig: 2 in
transverse section a resistance regulator constructed according to my Invention to
be worked by hand and Figs 3 and represent respectively inside elevation and
end view a portion of the same apparatus shewing an arrangement of switch for
suddenly breaking and reestablishing the circuit when required Figs 5 and 6
are detail views illustrating different arrangements for indicating the amount of
resistance or amount of compression to which the carbons are subjected and Figs: 7
and 8 represent a longitudinal section and transverse section respectively of a
modified construction of resistance regulator wherein the differential screws may be
caused to rotate together when required for the purpose of obtaining a quick
action Fig 9 is an elevation partly in section of an automatic resistance regulator
constructed according to my Invention Fig. 10 and 11 represent two modifi-
cations of contact makers which I employ in combination with my improved
resistance regulators and Figs 12. 13. 14 and 15 were diagrams illustrating
various applications of my improved resistance regulator and contact makers as
will be hereinafter described
Referring to Figs 1 and 2 A are the Carbon blocks or resistance supported
so as to be capable of sliding on or between guides B fitted in the interior of the
casing C In the end D of this casing is fitted to work a hollow screw E provided
with a hand Wheel F for facility of turning it.
This Screw is provided with an external thread and also with an internal thread
of less pitch than the outer thread in which works a corresponding screw G formed
on a rod or spindle H passing through the centre of the regulator.
The Rod or spindle H is connected at its inner end to a plate I which bears
against the rear of the carbons A.
When it is required to decrease the resistance the carbons are compressed more
or less as required by rotating the hand wheel F so as to cause the spindle H to
move in the direction of the arrow in Figure 1 and thereby compress the carbons A
between the plate I and the end D of the casing C.
It will be readily understood that by reason of the difference between the pitch
of the screws E and G the rod H will be caused to move very little in comparison
to the motion imparted to the hand wheel F the proportions between which
motions will be determined by the difference between the pitches of the two screws;
for example if the pitch of the outer screw thread E be equal to 11th of an inch
and that of the screw G equal to 16th of an inch one revolution of the hand wheel F
will cause the plate I to move and the Carbons A to be compressed to the extent
of part of an inch.
th
To the inner end of the spindle H is connected a rod or bar K which passes
through the end D of the casing C and is provided at its outer end with rack
teeth a which are made to gear with a pinion b fast on the arbour of a pointer c so
that when the spindle H is moved longitudinally the pointer c will be caused to
turn and indicate on the graduated dial L the amount of resistance or extent of
compression to which the carbons A are subjected.
Or for indicating the amount of compression the arrangement illustrated by
Figure 5 may be employed, which consists in causing the screw.G or other moving part.

page_text: of the apparatus to act upon the short arm of a lever or pointer C so as to cause
the long arm of the said lever or pointer to move over a graduated scale d and
thus indicate the resistance or amount of compression
J
Or the arrangement illustrated by Figure 6 may be employed which consists in
providing in any suitable position a graduated scale d which will indicate the
amount of compression by the distance the wheel E travels longitudinally along
the scale at each revolution of the screw whilst a portion of a revolution of the
wheel will be indicated by a scale e on the periphery of the wheel and a fixed
point on the edge of the scale d-By the arrangements described the most minute
amount of compression of the carbons A may be indicated on a sufficiently large
scale to be observed without difficulty
Figure 7 is a longitudinal Section and Figure 8 a tramsverse section of a modified
construction of variable resistence regulator constructed according to my invention
in which means are provided for causing the differential screws to rotate together
in order to obtain a rapid action when required-A are the carbons, B the guides
upon which they are fitted to slide and O the casing, all arranged as in the
modification herein before described.
The internal screw spindle H (which in this modification is not fixed to the
plate I) is provided at the end H, which passes through the end D' of the casing
with a groove or key way g on which is inserted a key h for the purpose of securing
on the end H' a bush i in such a manner as to admit of the spindle H moving
longitudinally in the bush but at the same time prevented from rotating therein
When it is required to reduce the resistance the hand wheel F on the outer
screw spindle E is rotated in the required direction to cause the inner screw G to
move longitudinally in the direction of the arrow and compress the carbons A
between the plate I and the end D of the casing-The screw G is prevented from
rotating with the screw E by the clamp k which is tightened up so as to grip the
bush i by means of the screw -If however a rapid longitudinal motion of the
screw spindle H be required the bush is released by turning the screw in the
opposite direction so as to admit of the said bush rotating freely in the clamp k;
then by rotating the hand wheel F¹ fixed on the end of the screw spindle H the
said spindle will be caused to travel in the outer screw spindle E and at the same
time the outer screw will by reason of the friction of the inner screw be caused to
travel in the end D of the casing and thereby produce a rapid Action on the
carbons.
In Figure 4 I have illustrated an improved construction of switch which may be
employed with either of the modifications of resistance regulators hereinbefore
described for the purpose of making and breaking the circuit when the carbons are
separated to their full extent and thus prevent the formation of a destructive arc
between the carbons of the regulator-It consists of a lever M centered at m to the
end D of the casing C the arm n of which lever is brought into and out of contact
with a stud p for the purpose of breaking and restoring the circuit in the following
manner.
Qis a stud carried by the outer screw spindle E which stud when the said
spindle has descended a certain predetermined distance comes into contact with a
projection on the lever M causing the same to turn on its centre m and remove
the arm n out of contact with the stud p and thereby break the circuit and
prevent an arc being formed between the stud and the lever M The screw E is
prevented from being further rotated by a projections on the opposite end of the
lever M (and consequently the carbons are prevented from being compressed before
the circuit is established) until the lever M is restored by hand to its former
position in contact with the stud p and the circuit reestablished for which purpose
the lever M is provided with a handle t
The arm n of the lever is held out of contact with the stud p after being started
by the stud q by a spring u which maintains it against a stop until removed'
by hand
g
According to another modification which is illustrated by dotted lines in this
-

page_text: Figure the arm n may be made to make and break contact automatically by the
stud q which as the hand wheel F, is rotated comes into contact first with the
projection to break the circuit and then with a tail piece formed on the lever
as shewn by dotted lines which will cause the lever M to turn to its centre m and
bring the arm n into contact with the stud p and re-establishes the circuit
Figure 9 is an elevation partly in section of an automatic variable resistance
regulator constructed according to my Invention
a a are piles of carbons which compose the variable resistance These carbons
are more or less compressed by means of a screw b actuated by means of a worm
wheel b¹ driven by a worm on the shaft which carries the bevel wheel 6*-This
bevel wheel gears with two smaller bevel wheels c c¹ mounted loosely on the
spindle d and provided with clutch teeth which are caused to engage the clutch e.
This clutch e is actuated by means of a lever e¹ which has connected to its end &
keeper or armature f playing between the poles of two magnets g g¹
The spindle d is kept revolving by means of a belt from the machine shaft or
any other convenient source of motion and as long as the machine is working
normally the clutch e remains and revolves in a central position without engaging
either bevel wheels c c but if the electro magnetic force increases the contact
maker sends a current through either of the coils 9 or gl as the case may be and causes
the screen 6 to revolve so that the carbons a. a are lowered and a greater resistance
put into the magnet circuit. When the electro magnetic force has again fallen to
its normal point the contact maker breaks the circuit through the magnets and the
armature freturns to its central position and the screw b ceases to operate-If the
magneto-electric force falls below the normal point the reverse of this operation
takes place
Figure 10 is an improved contact maker constructed according to my Invention
to be employed in combination with the regulators hereinbefore described
In this arrangement the suck of a solenoid h upon an iron core h¹ is balanced by
means of a spiral spring h² provided with means for adjustment on top; i is a
contact lever acting between two points The weight of which lever and core
is balanced by an adjustable weight so that in its normal position when no
current is flowing it remains in a horizontal position between When the
machine is started the spiral spring is adjusted to balance the desired electro
magnetic force so that if this force increases the lever i will be drawn down into
contact with the point and remains so until the required adjustment in the
resistance has been inade whereupon it will return to its midway position-If the
electro magnetic force diminishes the spiral spring h² will cause the lever i to
make contact with the upper stop and energise the other magnet
I have found that the most convenient form of contact to employ is a carbon·|
roller mounted loosely so as to revolve on the end of the lever i between the two
carbon pencils or points which carbon pencils are arranged slightly out of the
same axial line so that in the act of making contact the roller is slightly rotated
thereby exposing a fresh surface to the spark but any other convenient form of
contact may be employed such as platinum points or wire dipping into cups con-
taining mercury or acidulated water.
Figure 11 represents a modified construction of contact maker which operates in
precisely the same manner as that last described but the variations in the electro
magnetic force are measured by the contact maker i tilting between two coils L L',
L' being free to turn on an axis and the pull balanced by the tension of a spiral
spring has described with reference to Figure 10. In this modification a contact
is made at each end of the lever When the electro magnetic force is normal the
lever remains in a horizontal position as shown in the drawing without touching
either contact pieces Carbon may be employed in this form of instrument-This
arrangement may be very easily employed where it is desired to keep the Quantity
constant and to vary the electro magnetic force-In which case the coils would be
wound with thicker wire and placed in the main circuit whilst the regulator would
be as a shunt to the magnet circuit

page_text: There may be arranged with the regulators hereinbefore described a metallic
circuit which will short circuit the carbon resistance after the carbons have been
compressed to the full extent-In the automatic regulator in order to prevent
over compression of the carbons' I cause the pressure or thrust of the carbons to be
taken against the spring as shewn at win Figure 9 which when the pressure
exceeds a certain amount will yield and interrupt the circuit leading from the
contact maker to the magnet actuating the clutch thus preventing damage to the
regulator in case the contact maker should fail to act
Figure 12 is a diagram illustrating the application of the contact maker and the
automatic resistance regulator to a group of shunt dynamo-motors, N representing
the contact maker, O the regulator and P the dynamo-motors. The direction of the
current is indicated by the arrows and will be clearly understood by reference to
the drawing without further description.
Figure 13 is a similar diagram illustrating the contact maker and the resistance
regulator as applied to the controlling of the current of a series machine used for
arc lamps and Figure 14 is a similar diagram illustrating the contact maker applied
to a series of incandescent lamps the automatic resistance regulator being operated
by a separate motor Q taking its current from the main circuit
Figure 15 is a diagram representing the automatic resistance regulator actuated
by an electro motor Q but in this case the clutch described with reference to
Figure 9 is dispensed with and the compression and expansion of the carbons is
effected by the contact maker reversing the motion of the motor which may be a
magneto electric motor geared directly to the compressing screw
Having now described and particularly ascertained the nature of my said
Invention and the manner in which the same is or may be used or carried into effect
I would observe in conclusion that what I consider to be novel and original and
therefore claim as the Invention secured to me by the hereinbefore in part recited
Letters Patent is
First In apparatus for regulating or controlling electric currents the employment
of differential screws for effecting the compression and allowing of the expansion
of the carbon resistance substantially in the manner herein before described with
reference to Figures 1 and 2 of my drawings
Second In apparatus for regulating or controlling electric currents in which the
compression and expansion of the carbons is effected by means of differential
screws the provision of means by which a slow or by a rapid motion can be
obtained as required substantially as hereinbefore described with reference to
Figures 7 and 8 of my drawings
Third-In apparatus for regulating or controlling electric currents the combination
with the differential screws E and G of the slot g in the screw spindle H key h
bush i and clamp k for preventing the rotation of the inner screw but perinitting
of the longitudinal motion substantially as herein before described with reference to
Figures 7 and 8 of my drawings.
Fourth In apparatus for regulating and controlling electric currents the
combination with differential screws for compressing and separating the carbons of
an automatic or partially automatic switch for making and breaking the circuit
for the purpose of preventing the formation of a destructive arc between the
carbon plates themselves the said switch being constructed arranged and operating
substantially in the manner hereinbefore described with reference to Figures 3 and 4
of my drawings
Fifth The general construction and arrangement of resistance regulators for
controlling electric currents as hereinbefore described with reference to Figures 1.
2. 3. 4. 7 and 8 of my drawings
Sixth The general construction and arrangement of automatic regulator for
controlling electric currents as hereinbefore described with reference to Figure 9 of
my drawings
Seventh In automatic resistance regulators for controlling electric currents
operating the screw for effecting the compression and expansion of the carbons by

page_text: a clutch and gearing operated by an electro magnet substantially as hereinbefore
described with reference to Figure 9 of my drawings
Eighth The improved contact maker hereinbefore described with reference to
Figure 10 of my drawings
Ninth The improved contact maker hereinbefore described with reference to
Figure 11 of my drawings
In witness whereof I the said Percy Ruskin Allen have to this my Specification
set my hand and seal this twelfth day of May One thousand eight hundred
and nighty thwoo
PERCY R. ALLEN (L.S.) 1