A New or Improved Method and Apparatus for Effecting Economy of Electric Force in Electric Lighting.
Year: 1890

page_text: Date of Application (in United Kingdom), 19th Aug., 1890
Complete Specification Left, 19th Aug., 1·90-Accepted, 14th Feb., 1891
COMPLETE SPECIFICATION.
A New or Improved Method and Apparatus for Effecting Economy
of Electric Force in Electric Lighting.
We, PAUL ETIENNE BARDONNAUT and PIERRE JUPPONT both of Toulouse in
the Department of Haute-Garonne in the Republic of France Engineers do hereby.
declare the nature of this invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement :-
It is well known that the eye can be compared to a camera obscura into which
light penetrates, by a little circular orifice, the pupil, and then passes through
several transparent media and membranes; the watery humour in front of the eye;
the crystalline (a sort of lens capable of contraction); the vitreous humour
occupying the major part of the eye ball up to the retina, covering the back of the
same. It is the luminous rays reaching this delicate and very sensitive membrane
which gives us the sensation of external objects and colours.
After refraction in the divers media traversed, the luminous rays converge on the
retina where they produce an impression.
The sensation produced continues some moments after the disappearance of the
object which causes it, and it does not become entirely effaced until th of a
second after this appearance.
The following well known experiments are based on this principle
:-
1st. A disc, divided into sectors, coloured to represent the various shades of the
spectrum, the relative extent of which is about equal to that of the corresponding
colours in the spectrum itself, has imparted to it a rotary motion sufficiently rapid.
The sensations of the various colours are superposed and consequently we only
perceive a disc of a uniform white colour.
2nd. A luminous point is placed on a disc, and the latter is rotated rapidly. In
consequence of the persistency of the impression produced on the retina by the
luminous point, we perceive a perfectly unbroken luminous circle.
This experiment is easily performed with a lighted match held in the hand, and
to which a rapid rotary motion is given.
Wheasthone's photometer is also based on the same principle.
We have thought that this same principle could be applied to electric lighting
and would lead to great economy.
We have thought out the matter as follows:-
If we take an electric incandescent lamp and extinguish the same, the impression
of the light on the retina will continue for 16 of a second and the extinction of the
lamp is not perceived at all if the lamp be relighted within 1 of a second after its
extinction.
Consequently, if, during successive intervals of time of less than 1 of a second, we
interrupt the current which feeds an electric lamp, this lamp will be successively
extinguished and relighted, but the light produced will appear as fixed a one as if
he lamp had been constantly illuminated by means of a continuous current.
In

page_text: consequence, however, of the successive interruptions of the current, there will be a
great economy of electric energy. We have verified these facts by the experiment
described above.
It may also be remarked that in the case of an electric lamp, the illumination
continues even after the extinction of the luminous centre (that is after the current
is interrupted) during a longer time than that which we have mentioned above.
This arises from the heat of the lamp being maintained for a certain time after the
current is interrupted.
We have thus noted that when an incandescent lamp is extinguished the luminous
filament is perceived for some time afterwards owing to the heating of the filament.
In the same way when an arc lamp is extinguished, the carbons remain red for an
instant, and consequently the light still continues after the removal of the causes
producing it. We thus find ourselves in presence of two principles.
1st. The persistence of luminous impressions on the retina.
2nd. The persistence of the light after the extinction of incandescent or arc
lamps.
In order to put these principles into practice the idea occurred to us of employing
the following arrangement for electric lighting.
A disc C is placed in connection with a wire A B (Figure 1) communicating with
any source of electricity (a battery of any kind, accumulator, dynamo, et cetera) on
this disc there branch off to the terminals C₁, C₂ C₂ and C., four metallic wires a,
b, ca² 1² 2 a³ ³ ³ and a² 14 64 which transmit the electric current to the lamps L₁
L L L and then reunite in a single wire A' B'. (The intermediate wires need
not be reunited into a single cable A B but may go all separately to the source of
electricity.) The disc Chas a contact brush or rubber C D of any form to which
a rapid rotary motion is given. When the extremity D of the travelling brush CD
is in contact with the contact C₁, the current coming from the wire A B is
transmitted to the lamp L' by means of the wire a' b' and during the whole time
that the extremity D rests upon C₁, there is no transmission of electric fluid by
means of the terminals C2 C3 C4. In the interval 3-4 between C1 and C2 there
is no circulation of the current; from 4 to 5 whilst D is in contact with C², lamp L'
receives the current; from 5 to 6 the current is interrupted then it is transinitted
to L³ from 6 to 7; it is again interrupted between 7 and 8 then communicated to L₁
from 8 to 1, interrupted again between 1 and 2 transmitted to L' from 2 to 3, and
thus the cycle recommences.
The same
The electric lamp L₁ thus only receives the current during the space of time
occupied by the brush D in traversing the space 2 to 3 of the terminal C₁; during
the whole of the remainder of the time, that is to say whilst D goes from 3 to 2
passing over C, C, and C, the lamp L' receives no electric current.
applies to the lamps La L, L, which respectively only receive the electric current
during the time that the brush D takes in traversing the spaces 4-5, 6-7, 8-1.
The brush C D has imparted to it a rapid rotating motion by any sort of motor.
If our apparatus be suitably regulated and actuated with a speed sufficient to
prevent the retina from perceiving the extinction of the lamps Li L L³ and L, a
fight is obtained from each of these lamps as fixed and continuous (to all appearance)
as if the circuit A B was supplying a single lamp. By not allowing the extinction
of each lamp to continue more than 1 of a second, we have a light quite fixed.
The duration of the extinction can be even reduced to a still greater extent so that
it only reaches or son of a second or even less according to circumstances.
We can also allow the extinction to continue for a longer period as for
instance, or 15 of a second or even more.
In the example described above, it is supposed that the same wire fed four
electric lamps by means of four intermediate wires a¹ ba² 2-a³ ³-a¹¹-the
number of these lamps being very variable according to circumstances. For
instance the wire A B may only feed two lamps by means of two intermediate
wires a¹ a² 12; but it may also supply three, four, five, ten, fifteen, twenty and
even a larger number by means of as many intermediate wires.

page_text: The intervals between the contacts which are very large in Figure 1, may be,
much reduced, so far even as to allow the brush CD to rest on two contacts at a
time during a time function of the width of this brush.
The details given above show that our invention has a certain resemblance to.
that of Messrs. Meyer and Baudot for multiple printing apparatus.
If in fact, we examine what takes place in the working of Baudot's apparatus,
we see immediately that with the same battery we actuate one, two, three, four or
even a greater number of apparatus if the distance of the centres in communication
is not very great. It is sufficient for that, that the battery at the starting station.
have a sufficiently high electromotive force to allow the current supplied by it to
produce a useful effect in a very short time. But whilst Mr. Baudot endeavoured
to economise the wires transmitting the electricity, we, on the contrary, sought to
effect an economy in the electric energy to be employed for obtaining a given
illumination, by distributing the current successively over several wires. There
will be realised for the production of light-by reason of the prolongation of the
duration of its effect, due to the persistence of the impressions on the retina and
to the luminous effects resulting from the effect of the heat on the filament->
advantages as real as those which are attained in telegraphy by the use of
Baudot's apparatus. It is always possible to employ a current of a higher potential
than that which corresponds to what is called industrially, the "voltage" of lamps
in use, and it is always possible to place in the conductor leading from the
manufacturing station a movable distributor of any suitable pattern in accordance.
with the principles described before (Figure 1). It can be similar to Baudot's
distributor, for instance, a fixed disc divided into insulated sections traversed
successively by a metallic rubber or brush or even a disc revolving on its axis and
presenting its sections consecutively to a rubber or even a helix arranged on a
movable cylinder the various parts of which come successively in contact with
parallel rubbers, the extremities of which are on a generating line of the cylinder.
As a model distributor we also employed a hollow conical or cylindrical sleeve,
formed of metal strips insulated electrically one from another and against the
interior of which there rubs a brush A. B (Figure 6) with a horizontal or vertical
axis.. The brush being slightly longer than the radius of the circumference on
which the rubbers rest, the centrifugal force developed by the rapid rotation
insures the contact (Figure 6). The brush can even be loaded at B with a weight
which will still further increase the certainty of the contact.
The duration of the contact of the brush on the metal sections C¹, C2, C3, C4,
(Figure 1) being very short, it follows that the angular speed is extremely
great and that the rubber or brush must make a large number of revolutions. per
minute.
In order to diminish the wear and tear of the apparatus, afford increased security
in its action, etretera, we may employ the following arrangement which,. while
allowing the contact to be of as short a duration as may be desired, permits of the
angular speed being reduced as much as desirable.
Supposing we desire to send the current successively into four different
circuits bed with the aid of the brush A B (Figure 7),, we arrange, on the
circumference of a commutator or contact cylinder or plate of any one of the
types enumerated, a series of four contacts 1, 2, 3, 4 1, 2, 3, 4 ...
such numbers as may be desired. We connect electrically the corresponding
contacts: 1 with 11, 1".... 12 with 21, 21
3 with 3, 311
etcetera. By
this arrangement, the angular speed can be reduced to a considerable extent.
The number of divisions, and consequently. of supply wires, appears to be only
limited by the necessity of giving the current, discharged successively into each
circuit, time to produce the light in the lamps; and the more, the electromotive
force of this current exceeds that necessary for illuminating the lamps of a single
circuit, the more we can supply other separate circuits, without there being besides
an undue proportion between the results attained and the electromotive forces
of the current employed and the voltage of the lamps supplied, the intensity of
•

page_text: the light increasing much more rapidly than the temperature of the body
producing it.
As stated by us above, it is to be noted that Messrs. Meyer and Baudot
endeavour in their apparatus to reduce the number of conductors to be placed in
telegraph lines, whilst for the production of light we have to effect a saving in the
motive power. This economy is of itself of primary importance; since the
stations for producing the electric energy are generally at a short distance from
the points of consumption and hence the diminution of the diameter of the con-
ductor is only a very secondary consideration and a mere nothing, so to speak, as
compared with the general working expenses.
Our discovery can be applied to every system of electric light distribution :
lamps in derivation, in high tension, on simple circuits or mounted in groups, or
even on circuits composed, say, of three, five, or six wires whether these circuits
are supplied direct or by means of "feeders." It is sufficient if each of the
circuits receive by some suitable regulating device, the necessary amount of
energy.
It can also be applied to the production of light by batteries, accumulators,
continuous or alternating currents, in short to every method employed for the
production and distribution of electric light.
In the experiments made by us we have ascertained that with successive
emissions from a current of 120 volts lasting about 3 of a second, light was
produced simultaneously with all its brilliancy in eight lamps of 60 volts and
remained perfectly fixed.
The speed of the brush can further be increased or decreased within certain
limits without alteration of the results obtained.
We place an interrupter between the distributor and the lamps supplied, in order
that the current may be supplied to the circuit only after the brush has been set
in action, so as to avoid the destruction of the lamps which might be caused by
the excess of the electro-motive force of this current over that corresponding to
the voltage of the lamps. Care as to this is necessary and in order to perform it
automatically, we must employ some one of the methods used in practice for
preventing an excess of electro-motive force or for equalizing the circuits by the
aid of rheostats.
Automatic means must also be employed so as not to deliver the current into
the circuits before the brush shall have attained a suitable speed, a centrifugal
force regulator for instance. Finally, two distributors can be employed situated
one near the other, one of which can be set in action if the other should stop,
unless it be preferred to keep both in action together.
We annex herewith diagrams of some of the arrangements that may be
employed.
Figure 2 shows how the current of a machine can be sent successively into any
number of circuits with the help of a distributor and a common return wire.
This arrangement can be replaced by a double distributor cutting off the current
on entrance and exit (Figure 3) in order to avoid the common return wire which
may be inconvenient for large distributions.
The distributor can be of any form, for instance, it may be a disc having contacts
before which there successively passes a brush, which is constantly connected by a
brush with one of the terminals of the machine.
Or it can also be formed by a cylinder, the axis of which is connected to one of
the poles and the surface of which carries contacts successively making contact
with brushes, (Figure 4).
It can also be formed of a spirally-rolled strip the different points of which are
"successively presented to brushes, the extremities of which are in a straight line.
A large number of similar arrangements can be employed, for instance, contacts by
gearings or brushes, conical or cylindrical surfaces..
The movable arm or the cylinder of the distributor, whatever may be its form,
can be set in motion by any kind of motor, a weight,, clockwork, an electric, water,

page_text: ga, or steam motor etc., or by the motor which supplies the motive power to the
generator of electricity, or by a transmitter of motion worked from the dynamo à
itself.
In order to avoid or diminish sparks, the rubbers can be regulated in such a way
that they always touch two or more contacts, and avoid breaking the current.
The cables connecting the dynamo to the distributor can end in the producing
station itself and in that case the distribution of the current to the different circuits
is made in the station itself.
The double distributor, shown in Figure 3, can be formed of two discs or two
cylinders or cones described above mounted on the same axle and set in motion by
the same motor.
Figure 5 shows a mode of applying the invention to an existing 3 wire system
with "feeders."
The brush A B sends the current successively on each side of the wire. .
The advantages of a 3 wire mounting can be preserved by sending the current
successively over each of the "feeders" with machines mounted in tension. There
are then three rubbers, one for each wire.
We will not enumerate here all the arrangements which can be adopted; they
are as numerous as the methods of distribution.
Whether the apparatus be in tension, derivation, on a double wire, on a loop,,on
three wires, etcetera, or whether the current be continuous or alternating the
method for which we request a Patent can be applied in all of these cases by
making use of similar methods to those just described by us.
And in all these cases whatever the details of the application may be, the com-
mercial result consists in the economy of work effected in the producing of a given
amount of light.
The regulation of the intensity and of the electro-motive force can be done by
means of the ordinary regulating devices, by the insertion of resistances either in
derivation on the circuits if it be indispensable to have the same current on each of
them, or by resistance in circuit for maintaining a given electromotive force at the
terminals of the lamps in use.
When working with a current of 120 volts and passing it successively into
8 lamps of 60 volts each, we ascertained that with successive discharges lasting sho
of a second, the light was produced simultaneously with all its brilliancy in the
8 lamps, and that it remained perfectly steady. From this it results that, with a
current of 120 volts, we have, without increasing the working power, illuminated
8 lamps of 60 volts: consequently, a continuous current of an energy double that
which was necessary for keeping a single lamp illuminated sufficed, when divided,
to supply 8 lamps of the same type, that is to say, in this way we effected an
economy of 75 per cent. in the working power.
This method, which we desire to patent in its application to electric lighting,
allows of the transportation of the motive power and of other applications of
electric energy.
In these latter cases, however, the same advantages as in electric
lighting would not be obtained.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, we declare that
what we claim is :--
1. The method of economising the electric current in electric lighting which
consists in distributing the main current in a series of interrupted currents through
a series of electric lamps (or series of lamps) in succession as described, the main
current having a power very considerably less than the total voltage of said lamps,
and the periods of interruption for the current through any given lamp (or series of
lamps) being of such short duration that said lamp (or series of lamps) appears to
the eye to emit a constant amount of light, substantially as described.
2. The combination with a series of electric lamps connected by separate inter-
mediate conductors with the main circuit, of a distributing apparatus consisting of a

page_text: series of insulated contacts each connected with its respective lamp conductor and of a
conducting brush or rubber in constant electric connection with the main circuit and
brought successively in contact with said contacts at such a speed that the current
to any given lamp is not interrupted for a sufficient length of time to permit a
fading of the light in said lamp to be apparent to the eye, whereby a much less
powerful current may be employed in the main current than would have been the
case had each lamp in the series been supplied with a constant current corre-
sponding to the voltage of the lamp, substantially as described.
Dated this 18th day of August 1890.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicants.