IMPROVEMENTS IN APPARATUS FOR PRODUCING ELECTRIC LIGHT
Year: 1879

page_text: LETTERS PATENT to Benjamin Alfred Raworth, of Manchester, in the County
of Lancaster, Engineer, for the Invention of "IMPROVEMENTS IN APPARATUS
FOR PRODUCING ELECTRIC LIGHT."
Sealed the 1st July 1879, and dated the 3rd January 1879.
PROVISIONAL SPECIFICATION left by the said Benjamin Alfred Raworth
at the Office of the Commissioners of Patents on the 3rd January 1879.
BENJAMIN ALFRED RAWORTH, of Manchester, in the County of Lancaster,
Engineer. "IMPROVEMENTS IN APPARATUS FOR PRODUCING ELECTRIC LIGHT."
The first part of my Invention relates to the commutators of machines for
generating electric currents, and has for its object the continuous cleansing of the
insulating sections of the commutators whilst in motion from all metallic particles.
For this purpose I employ a brush in contact with the commutator, to which I
impart a rotary or reciprocating motion.
The second part of my Invention is for applying a magnetic alarm or indicator
to electro-magnetic or dynamo electric machines, which on the occurrence of any
interruption in the circuit or sudden diminution of the electrical resistance shall
arrest the attention of the attendant, or in default of his presence shall stop the
action of the machine.
The third part of my Invention is for the combination with a dynamo electric
machine of a simple galvanometer and an indicator of magnetic attraction, in such
a manner that a reference to the two instruments will at once show whether the
whole of the current is traversing the external circuit or whether part of it is
leaking past the internal connection of the machine. The fourth part of my Inven-
tion is for a system of dividing electric currents in definate proportions by means
of mercurial resistances under control of electro magnets opposed to the action of
springs or weights; for this purpose I propose to use blocks of vulcanite or other
nonconducting substance cut in V shaped grooves containing mercury, the depth
of the mercuary in the grooves being regulated by the above mentioned electro
Price R71

page_text: magnets in connection with a flexible diaphragm. The fifth part of my Invention
consists in a novel form of electric lamp or regulator, in constructing which I
propose to employ two rods or tubes depending from a box containing the regu-
lating gear, one rod to be in connection with the positive pole and the other with
the negative pole of the machine or battery, which rods or tubes are to form slides
for the carbon holders. I propose to clamp the carbon rods in sections of spheres
held together by a pair of hollow conical clips with screw adjustment. I propose
to use a copper disc revolving between the poles of an electro magnet in place of a
fly as has been common heretofore, and I propose to connect the carbon holders
with the regulating gear by means of a string or other flexible medium.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Benjamin Alfred Raworth in the Great Seal Patent Office on the 3rd
July 1879.
BENJAMIN ALFRED RAWORTH, of Manchester, in the County of Lancaster,
Engineer. "IMPROVEMENTS IN APPARATUS FOR PRODUCING ELECTRIC LIGHT."
My Invention relates in the first place to the commutators of machines for
generating electric currents, and has for its object the continuous cleansing of the
insulating sections of the commutators whilst in motion from all metallic particles.
For this purpose I employ a brush in contact with the commutator, and I impart
to the brush n rotary or reciprocating motion either directly from the machine itself
or from some shaft in its vicinity.
The second part of my Invention is for applying a magnetic alarm or indicator
to electro magnetic or dynamo electric machines, which on the occurrence of any
interruption in the circuit or sudden diminution of the electrical resistance shall
arrest the attention of the attendant, or in default of bis presence shall stop the
action of the machine. It sometimes occurs that where the electric machines or
generators are placed at a considerable distance from the electric lamps one or
more of the lamps may become extinguished without the attendant becoming aware
of the fact; the extinction may arise from the carbons failing to run together or
from the conductors touching each other, or from a short circuit being established
in the lamp or in the machine. Sometimes the carbon points get into contact with
each other, which dims the light and heats the machine. My Invention causes a
bell to ring whenever any of the above named accidents happen, and in the case of
a short circuit being made for the current, which, if allowed to continue, would
injure the machine, it diverts the current from the electric magnets and thereby
stops all further action.
Fig. 1, Sheet 1, is a cross section of Siemens' dynamo electric machine, and
Fig. 2 is a plan shewing the method of applying the magnetic alarm; a, a, are the
electro magnets excited by the coils a¹, a¹, through which the current circulates.
Above the magnets I fix a frame b which carries a piece of iron b' supported on
pivots 62, the spring 68 holds the iron tongue 61 away from the magnets in opposition
to their attractive force. When no current is passing the tongue b¹ and the indi-
cator finger 6 occupy the positions shown in the Drawing, and the finger 6 bearing
against the spring closes an electric circuit excited by a battery, and rings a bell
placed in any convenient position. If the carbon points should come in contact
with one another the attraction of the magnets for the tongue becomes strong
enough to move the finger to C, which will also have the effect of closing the
electric circuit and ringing a bell. In the event of a short circuit being established
the strength of the magnets will be further increased, and the shunt C³ will be put
in contact by the finger 6, thereby providing a path for the current without its
traversing the coils a', a', which will stop the action of the machine instantaneously.
The shunt will remain in action until readjusted by the attendant. The third
part of my Invention is for the combination with a dynamo electric machine of a
simple galvanometer and an indicator of magnetic attraction, whereby a reference
to the two instruments will at once show whether the whole of the current is
traversing the external circuit or whether part of it is leaking past the internal
connections of the machine. The galvanometer may be any of those commonly in
use, and the indicator of the magnetic attraction may be such as that shown in
Figs. 1 and 2, the finger 6 indicating on the marked segment 65 the strength of
the magnets a, a, or a magnetic needle may be placed on the coils, as shewn at d,
its movement being resisted by a spring. The galvonometer being placed on the
external circuit at some distance from the machine, and the machine being put in
operation the dials of the galvanometer and magnetic indicator are marked in unison
for various strengths of current; then if at any time the magnetic indicator should

page_text: point to a higher figure than the galvanometer it will show that part of the current
does not leave the machine, and that consequently its insulation is defective.
The above inentioned indicators and alarm are applicable with very slight
modifications to other forms of dynamo electric machine than the one shown in
the Drawings.
The fourth part of my Invention is for a system of dividing electric currents in
definite proportions by means of mercurial resistances under control of electro
magnets opposed to the action of springs or weights. Referring to Sheet 1, Figure 3
is a vertical section; e is a cylindrical vessel divided in two by the disc of vulcanite
or other non-conducting material e'.
The surface of the disc e¹ is cut in V shaped grooves, a plan of which is shewn
at Figure 4; the grooves are partially filled with mercury and are connected with
one another so as to form one circuit, commencing at e² and ending at e³
Chambers are cut in the lower side of the disc e, communicating with the V
grooves by numerous passages e. There are as many chambers as there are
A thin sheet of india rubber F is cemented to the lower side of the
passages e.
disc e, and the space between it and the moveable diaphragm g is filled with water
or other liquid which spreads the pulsations of the lever 7 equally over all the
chambers e, causing the mercury to rise or fall in the grooves as less or more
resistance is required.
One end of the lever g' is shown in gear with the diaphragm g, the other end of
the lever is coupled to a similar arrangement not shown in the Drawing. The
current enters at and divides in the direction of the arrows; one half passes
through the electric magnet k¹, and thence through the V grooves and out by the
wire 2, the other half passes through the other half in the machine exactly similar
to that shown in the Figure; the spring m resists the pull of the electro magnet kl.
When either half of the divided current becomes stronger than the other the
lever g is thrown out of balance by the electro magnets and the resistances of the
mercury in the V grooves are altered by having a greater depth of mercury forced
into the grooves in one set, and by the depth of the mercury in the grooves of the
other set being correspondingly reduced.
If one half of the above arrangement be used it may be applied to the regulation
of an undivided current. The top half of the vessel is filled with water to take
up the heat caused by the resistance of the mercury; the cistern must be fed from
an inverted bottle or with a ball tap to keep the water always at the same level.
There must be enough mercury in the chambers to flood over the tops of the V
grooves when the current falls appreciably below the norinal amount.
The fifth part of my Invention consists in a novel form of electric lamp or regu-
lator, in constructing which I employ two rods or tubes depending from a box
containing the regulating gear. Fig. 5, Sheet 1, is a side elevation of the lamp;
is the box containing the regulating gear, and the two tubes m³, m², hang down
from it. The tube is in connection with the negative pole of the machine or
battery, and the tube m² with the positive pole. The carbon holders m³, m*, slide
upon the tubes m³, m², but each carbon holder is only in electrical contact with one
tabe. There are insulating bushes at n, n. All the insulating bushes and plates
throughout the lamp are marked n. The carbon holders are supported by the string
o which passes round a snatch block o' to give the negative only half the motion of
the positive carbon. p is a pillar on which the lamp may stard. The positive pole
of the machine is in connection with the pillar, and the negative leading wire is
insulated and carried up the interior of the pillar to pl where it makes contact with
the lamp. The pillar makes contact at p². When it is desired to suspend the lamp
it may be hung by the two hooks q¹, q², each of which is in connection with one of
the tubes m¹, m². Fig. 6 is a full size section of one of the carbon bolders
showing the carbon rod carried in a spherical clamp which is cut in three
sections and held together by the conical clip.
Fig. 7, Sheet 2, is a longitudinal section, and Fig. 8 a sectional plan of the regu-
lating gear contained in the box l. The string o passes over the grooved pulley o*;

page_text: one end of it is fastened to the positive carbon bolder », and the other end is secured
to the lever o'. The grooved pulley o³ is connected by a train of spur gear with the
copper disc S which revolves between the poles of the electro magnet S'. The
magnet S attracts its armature S as soon as the current is established and
separates the carbons a small distance.
In the event of the current failing or nearly failing the spring S³ overcomes the
attraction of the armature, and by means of the catch and ratchet wheel sets
the train of gear in motion and causes the carbons to approach one another.
A sinal electro magnet also regulates the motion of the train of wheels by
pressing on the copper dise with the finger . The action of this finger is regulated
by the spring and rod t which is in connection with the thumb screw to, Fig. 5.
The spur wheels in the train of gear are indicated by dotted circles. m³, m³, are
terminals for attaching leading wires from the machine or battery when the other
means of making connection are not convenient.
u is a catch for stopping the action of the lamp; it is worked by the thumb screw
, Fig. 5.
A modified form of the regulating gear is shown at Fig. 9, Sheet 2, in elevation
and partly in section. Fig. 10 is an end elevation and Fig. 11 a plan. In this
arrangement there is only one electro magnet v, its armature is hinged upon the
brass plate v and carries the lever v³. The spring resists the attraction of the
magnet. The grooved pulley 03 and its spur wheel are mounted on the boss of a
tumbler plate to which is moved by the rod w¹ in connection with the armature vl.
The pinion of is carried ou a plate o mounted on a boss formed on the back of the
tumbler 10. The pinion of carries a ratchet wheel of and a plain wheel 0. The
plate w lears against the wheel of and acts as a break. The action is as follows:-
As soon as the circuit is established and the current flows through the coils of the
electro magnet the armature is attracted and the lever descends, and in so
doing lowers the end of the string attached to it at 6, and by means of the con-
necting rod w¹ causes the tumbler plate w to turn on the stud x. The end of the
plate wo bears against the wheel o" and prevents it and the pinion of from revolving,
consequently the grooved pulley 08 is carried with the tumbler w and the string
suspending the carbon holders is raised on the positive side and lowered on the
negative side; the carbon points are thus separated a small distance. As the points
are gradually burned away the current diminishes and the magnet v allows the
spring to draw away the armnature; this reverses the motion of the tumbler frame
and puts the carbons closer together. The pawl gears with the teeth of the
ratchet wheel of and also assists to put the carbons closer together. As soon as the
current has recovered its strength the armature is again attracted by the electro
magnet and the carbons are separated, but they are permanently closer together by
reason of the pawl acting on the wheel o³.
Should the circuit be interrupted the spring draws the armature away to the
full distance and the plate w² rests against the stud w, fixed in the frame, thereby
easing the pressure of the plate w against the plain wheel oº, thereby allowing the
carbons to fall together.
When the friction of the carbon holders is too great for the electro magnet to
overcome with facility I employ a shunt carried in a frame 2. is a sliding pin of
brass carrying a stud 2 of ivory and a stud 3 of brass faced with platinum.
The finger makes contact with the coils of the inagnet at any desired point,
the covering of the wire being removed. The plate w is in connection with the
positive pole of the machine or battery through the screw ³. The pin acts as
contact maker. When the strength of the current decreases a little the pin
makes contact with the stud which shunts part of the coils of the magnet and
reduces its opposition to the spring . As soon as the current recovers a little of
its strength the pin 2 moves froin to and the magnet recovers its full strength
and again attracts the armature. The play in the joints is sufficient to allow the
pin to make and break contact without the carbon holders being moved.

page_text: The casing and other parts of this arrangement of lamp are the same for the other
arrangement shown in Figs. 5, 6, 7, and 8.
Having now fully described and ascertained the nature of my Invention and by
what means the same is to be carried into effect, I desire it to be understood that I
claim as novel and my Invention,―
First. The continuous cleansing of the commutators of electric machines by means
of a brush, as described.
Second. The use of a magnetic alarm and indicator for the purposes named, sub-
stantially as described and shown in Figs. 1 and 2.
Third. The combination with a dynamo electric machine of a galvanometer and
an indicator of magnetic attraction, as and for the purposes described.
Fourth. The method of dividing and regulating electric currents, substantially as
described and shewn in Figs. 3 and 4.
Fifth. The arrangement of electric lanp, carbon holders and regulating gear,
substantially as described and shewn in Figs. 5, 6, 7, 8, 9, 10, and 11.
In witness whereof, I, the said Benjamin Alfred Raworth, have hereunto set my
hand and seal, this Second day of July, One thousand eight hundred and
seventy nine.
BENJAMIN ALFRED RAWORTH. (..S.)