IMPROVED MEANS AND APPARATUS FOR ELECTRIC ILLUMINATION
Year: 1878

page_text: LETTERS PATENT to Charles William Siemens, of No. 12, Queen Anne's Gate,
Westminster, in the County of Middlesex, for the Invention of "IMPROVED
MEANS AND APPARATUS FOR ELECTRIC ILLUMINATION."
Sealed the 20th December 1878, and dated the 22nd October 1878.
PROVISIONAL "SPECIFICATION left by the said Charles William Siemens at
the Office of the Commissioners of Patents on the 22nd October 1878.
CHARLES WILLIAM SIEMENS, of No. 12, Queen Anne's Gate, Westminster, in the
County of Middlesex. IMPROVED MEANS AND APPARATUS FOR ELECTRIC ILLU-
MINATION."
"
My Invention relates to means of producing illumination by electricity, and
apparatus for that purpose. I adjust and fix two metallic or other conducting
terminals at a suitable distance apart so that an electrical current will pass from the
one to the other, forming a voltaic arc in the small space between them. I keep
these terminals cool by means which I will presently describe, so that they then-
selves undergo no material waste and their distance therefore remains practically
constant. In order to increase the luminosity of the are I introduce between the
terminals refractory material by preference rich in carbon, and I provide means of
moving this material slowly onwards so that as one portion becomes wasted it is
succeeded by fresh material brought into the presence of the terminals. Several
lamps arranged according to my Invention may be placed in one circuit,
but in order that if one or more of these be purposely extinguished the others may
continue to act, I provide means whereby the extinction of each effects automatically
a short circuiting of the electric current enabling it to act without interruption on
the others.
Having thus stated generally the object of my Invention, I will describe as an
example, the nature of an apparatus whereby I carry it into effect. In this
apparatus I make the terminals in the form of thimbles or short pieces of tube
which may be of mild steel or other suitable metal, each of which is open at one
end and closed in hemispherical form at the other end. The hemispherical ends of

page_text: the two thimbles are presented towards each other, and the thimbles being connected
In order
in the electrical circuit, the voltaic arc is produced between those ends.
to keep the thimbles cool I place within each a smaller tube through which I direct
a current of water which plays on the interior surface of the terminal, abstracting"
heat therefrom, and issues from the terminal by the annular space surrounding the
inner tube. In order to prevent conduction of the electricity by the water or the
pipes conveying it to and from the terminals I make those pipes of non-conducting
material such as caoutchouc, gutta percha, vulcanite, glass, porcelain, or the like, and
of such length that there is sufficient resistance in the length of water column, to
prevent serious loss of electricity, and for still more effectually providing against
such loss I render the water currents discontinuous by allowing them to fall freely
-through heights-sufficient to divide them into detached-drops or masses of water.
The material introduced between the terminals a little behind their apices may be
in the form of a stick or rod presenting its edge or end between them, and moved
gradually onwards in the direction of its length so as to bring fresh portions of
inaterial into the range of the arc. It is convenient, however, to make this material
in the form of a disc or wheel mounted on an axis so as to present its edge between
the terminals and to give this disc a slow rotation. This movement may be derived
from clockwork or other convenient motor. It is advantageous, however, to obtain
it without recourse to any extraneous power, and for this purpose I cause the current
of water supplied to one of the terminals or issuing from it to turn a turbine or
re-action wheel which by means of reducing gear gives the disc the slow rotary
motion required. The disc or the outer portion of it is made as stated of refractory
material preferably rich in carbon, such as graphite, plumbago, or a mixture of these,
or of carbon with calcareous or aluminous substances which may be made into a
paste and moulded to the form required. It is of advantage to coat the outer edge
of the disc with carbon or metallic substance so that when the lamp is to be put in
When the whole
action an immediate kindling of the luminous flame is effected.
edge of the disc has been consumed it is removed and a fresh disc is mounted in its
place. When instead of a disc a rod moving longitudinally is employed, on one
length of rod being consumed another can be made to follow it closely so that there
is no interruption of the action. The rod or disc placed with its edge immediately
behind the apices of the terminals, besides supplying material which gives luminosity
to the voltaic arc, operates also as a reflector, increasing the intensity of the light.
For the purpose of short circuiting the current when the lamp is not in use, I mount
on a contact lever a counterbalanced funnel or vessel which receives water issuing
from one of the terminals and discharges it by an adjusted outlet so that there is in
the vessel a certain quantity of water which overbalancing the counter-weight
But should the flow of
moves the contact lever so as to bring the lamp in circuit.
water through the terminals be stopped, then the funnel or vessel emptying itself
ccases to overbalance the counterweight, and the contact lever thereupou moves to
such a position as to break contact for the lamp and to make contact for the other
part of the circuit. I have above described the use of water as means of cooling
the terminals, but it is to be understood that air might also be employed for this
purpose, particularly if it be arranged so as to expand within the terminals from a
state of considerable condensation. When air is thus employed the issuing current
from one of the terminals may be directed against the vanes of a wheel so as to
produce the rotary motion for giving movement to the carbonaceous disc or rod
also the current of air may be made to play against a vane or plate attached to the
contact lever for the purpose of bringing the lamp into circuit, and for breaking
contact with the lamp and completing the external circuit when the air supply is
stopped.
For one of the terminals above described presenting its apex to the othe
terminal might be substituted a pipe of conducting material presenting its side to
the other terminal, water being caused to circulate through the said pipe in order to
keep it cool. A number of terminals might be presented to one such pipe so as to
produce a number of lights arranged in a row, a circle, or any other desired form.

page_text: Also the terminals instead of being made in the form of thimbles, might be hollow
wheels with rounded edges presented towards each other and caused to revolve
slowly, water being made to circulate within them. Or the wheels might be solid,
revolving with part of their circumferences immersed in water, or cooled by currents
of air directed against them and through perforations in their bodies. When a
number of lights such as I have described are supplied with electricity from one
source in one continuous circuit, I provide at each lamp a rheostat of resistance
equivalent to that of the lamp itself, so that when the lamp is thrown out of the
circuit the other lamps shall not be affected. When the lights are supplied by
branches from the same source I provide for each branch a current regulator such as
I have described in a Provisional Specification filed by me on the 7th June 1878,
No. 2281, so that the supply of electricity to each light reinains uniform notwith-
standing variations in the number of circuits and in the productive power of the
dynamo-electric machine or other source of electricity employed.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Charles William Siemens in the Great Seal Patent Office on the
21st April 1879.
"
CHARLES WILLIAM SIEMENS, of No. 12, Queen Anne's Gate, Westminster, in the
County of Middlesex. IMPROVED MEANS AND APPARATUS FOR ELECTRIC ILLU-
MINATION."
My Invention relates to means of producing illumination by electricity and
apparatus for that purpose, which I will describe with reference to the accompanying
Drawings.
An important part of my Invention consists in arrangements for keeping the
terminals of an electric lamp cool, so as to avoid the fusion and dissipation of
the material of which they consist by the intense heat of the voltaic arc, and thus
I am enabled to employ metal which is subject to no material waste either for both
terminals, with carbonaceous matter interposed between them, or for one terminal,
the other being carbonaceous. Fig. 1 is a section of a pair of cooled metallic ter-
minals with interposed carbon, according to my Invention. A and B are two
metal thimbles or closed tubes screwed or otherwise fixed on stationary tubular
supports A and B¹. Within these are fixed smaller tubes a and b, which are
connected by caoutchouc, glass, stone ware, or other non-conducting tubes with a
water supply. Between the terminals is placed a rod or slab C of imperfectly
conducting material rich in carbon or faced with carbon. This rod or slab is
guided between rollers c, c, so that it can advance as its end becomes wasted.
Water being supplied to the tubes a, b, and the terminals A, B, being connected in
an electric circuit, the luminous voltaic arc is presented between the end of C and
the terminal B, and the terminals are kept cool by the flow of water through them,
as indicated by the arrows.
Instead of cooling both terminals by water, one only, the negative terminal, may
be so cooled, the other, or positive terminal, being of carbonaceous material, which is
most conveniently made in the form of a disc caused to rotate slowly, and also to

page_text: advance towards the negative terminal as its edge becomes consumed. Fig. 2 is a
side view partly in section of a lamp so arranged with means for automatic adjust-
ment of the distance of the terminals, as well as for the automatic feed of the carbon
asrit-is-wasted, and for automatic extinction of the lamp when the supply of water
is arrested. The negative metallic terminal B with its internal-water-tube-b-is.fixed_
at the end-of-a-tubular-arm-B!, which is pivotted to the framing of the lamp at B2,
-and-which on its short extended arm carries an armature B³ immediately under the
pole of an electro-magnet D. The arm Bis supported on a spring B' adjustable
by a screw. Its interior is connected by a piece of flexible non-conducting tube b¹
to a water supply, so that water can flow-through. it. and the tube b into the upper
part of B, and thence down an outlet tube 63 along a non-conducting channel 68
into-a cistern E. This cistern is supported on a spring E¹ of conducting material,
and immediately under it there is a contact screw E2 fitted-in an insulated saddle
E3 which projects down from the fixed framing of the lamp. The spring E³ is
adjusted in strength, and the contact screw E2 is adjusted in position, so that when
the cistern E is empty, or nearly so, contact with E2 is broken, as shewn in Fig. 2;
but when the cistern E is filled, or nearly so, with water up to the level of the top
of its overflow pipe e contact is made with the screw E. At the bottom of the
overflow pipe e there is a small hole e', which is not sufficient to keep the cistern
empty while there is a full flow of water into it from the terminal B, but which
serves to empty the cistern when that flow is stopped. As one of the wires W' by
which the lamp is brought into an electrical circuit is attached to the saddle E³, and
the circuit of the lamp includes the spring E¹, it follows from the arrangement des-
cribed that it is only when the cistern E is supplied with water that has passed
through the terminal B that the lamp is brought into circuit by contact with the
screw E2, and that when the water supply is stopped by closing a stop-cock or other-
A small
wise the contact with E2 is broken, and the lamp is thrown out of circuit.
spring e2 is provided to tail off the residual electricity, and prevent the spark from
damaging the contact surfaces. In the modified form of lamp, shewn chiefly in section
at Fig. 3, and in front view, with part in section, at Fig. 4, the arrangement. of
cistern and water terminal is similar to that above described with reference to
Fig. 2, except that in this case the water terminal B consists of a continuous tube
bent round upon itself, and the automatic adjustment of its distance from the other
terminal is effected in a different manner. All the parts in Figs. 3 and 4 corre-
In the modified form
sponding with those in Fig. 2 are marked by similar letters.
of lamp shewn in vertical section at Fig. 5, and in front view at Fig. 6, the cistern
and its contact making and breaking arrangement are dispensed with, the water
cooled terminal B being in this case a bent tube communicating with the top and
the bottom of a tubular vessel B, which exposes a considerable surface for cooling,
so that a continual circulation of water goes on through the terminal, the water
there heated ascending to the top of the vessel B³, and the water descending
therein as it cools to flow again through the arm B¹ and the terminal B. As the
arm B-and-terminal-B-have-an_adjusting movement, which will be presently
explained, pieces of flexible tube 61 and 64 are employed to connect the moveable
parts with the stationary vessel B³. I will now describe the construction of the
other or positive terminal of the lamp and the mechanism for giving it a forward
feeding movement as its substance is consumed. As the arrangements for this
purpose are similar in the three forms of lamps shewn respectively in Fig. 2, in
Figs. 3 and 4, and in Figs. 5 and 6, I have marked corresponding parts in those
Figures with similar letters; and it will be understood that the following
description of the positive terminal and its feeding mechanism applies to those
different forms of lamp. The positive terminal A is a disc of carbonaceous material
mounted on an axis A' which is retained by radius yokes A2 pivotted at A³ to the
fixed framing of the lamp, so that it can move up or down in a circular are nearly
coinciding with a vertical line. The axis A¹ moreover rests on the curved edges of
arms C' of levers pivotted to the fixed framing at C. These levers are counterbalanced,
so that the axis Con which they can turn coincides as nearly as possible with their

page_text: centres of gravity. The edge of each of the arms C¹ is of a volute or spiral
curvature, the upper part being farthest from the centre C and the lower part
nearer thereto. On one of the radius yokes A³ is mounted a train of multiplying
gear connecting a flyer F with a toothed wheel a on the axis of the terminal A,
so that a moderately slow rotation of the terminal shall give rapid rotation to the
flyer. The disc A resting on what may be considered the sloping edges C', and
being itself spiral in outline, so that one side is heavier than the other, tends to
rotate in the direction of the arrow, and its axis by frictional contact with the
edges of C' tends to move the arms C¹ upwards, thus the part of its edge G pro:
sented towards the negative terminal tends to approach it by rotation towards it,
and also to descend towards it by an amount due to the sloping curvature of the
arms C¹; its movement being governed by the flyer F, which itself is regulated
automatically by an arrangement of mechanism that also automatically determines
the distance between the terminals A and B. The rotating movements of the
disc A may be farther ensured either by a weight suspended by a cord wound
on the axis A¹ or in the case where there is a continuous supply of cooling water
by means of a small turbine or re-action wheel driven by the water current.
For the purpose of automatically determining the distance of the terininals A
and B I employ two modes of action, the one being that of an electro-magnet,
as in the lamp shewn by Fig. 2, and the other being that resulting from the
expansion of a metal strip when heated by the passage of electricity through
it, as in the lamps shewn respectively in Figs. 3 and 4 and in Figs. 5 and 6.
Referring in the first place to the electro-magnetic arrangement of Fig. 2 there is an
iron core D adjustable in height by a screw D₁ and surrounded by a coil of insulated
wire which, as will be seen by the connections D2 and D³, is in the circuit from the
terminal B, arm B', and the bracket carrying the pivot B² to the spring E¹, screw
E2 (when there is contact therewith), to the wire W¹. The other wire W2 conveys
electricity through the yokes A² to the disc A, and thence it passes at the point G
to the terminal B. To the arm B¹ is attached a lever F' having at its top an adjust-
ible screw F2 which is presented towards the wings of the flyer F. At first when
the lamp is out of circuit the spring B raises the terminal B close up to the disc A
and withdraws the screw F2 from the flyer F. Water being supplied so that contact
is made with E as already described the electricity passing through the coil of the
electro-magnet D causes it to attract the armature B³ so withdrawing B from
contact with A, whereupon the luminous are is presented between G and B. At the
same time the movement which withdraws B causes F2 to come in the way of the
flyer F, preventing its revolution and so preventing the rotation of the disc A.
When, however, owing to the consumption of the material at G the distance between
G and B becomes so great as to weaken the current the magnet D exerting less
attraction on the armature B³ the terminal B is again permitted to approach A, and
the top screw F2 being withdrawn the flyer F is left free to revolve, so that the disc
A can turn partly round, bringing the lip G nearer to B. Thus as the material of A
becomes wasted there is an approach of the terminals regulated by the amount of
electricity passing through them, and by proper regulation of the adjusting screws
setting the contact at E2, the force of the spring B, the position of the core D and
the stop F, the luminous are maintains itself in a condition nearly constant. In
the lamps shewn in Figs. 3 and 4, and in Figs. 5 and 6, instead of an electro-magnet
for regulating the distance of the terminals and the feed of the disc I employ a thin
strip of metal H suspending the arm B' from an insulated adjusting screw H' at the
top. The electrical connections in Figs. 3 and 4 are as follows:-The current sup-
plied by the wire W passes through the yokes A² to the disc A thence to tho
terminal B and its arm B₁ through the metal strip H and screw H¹ by the wire H³
to the spring E, and thence, when there is contact with E, to the wire W'. In
Figs 5 and 6 the connections are from W2 through the body of the vessel B and the
bracket projecting from it through the yokes A² and the disc A, thence to the
terminal B and its arm B₁ through the strip H and screw H¹ to the wire W'. In
both cases the strip H is in the circuit of the lamp, and according as a greater or less

page_text: quantity of electricity passes through the strip so it becomes more or less expanded
in length, giving movement to the terminal B away from or towards A, and at the
same time moving the stop lever F¹ so as to arrest or release the flyer F, thereby
stopping the rotation-of the disc.A or allowing it to proceed. When water is em-
ployed as above described for keeping a terminal cool it is necessary to-introduce.in
some part of the pipe connecting the terminal to the water supply a portion of non-
conducting pipe, such as the flexible pieces b' in Figs. 2 and 3, and b and bin
Fig. 5.
Although the water contained in these pieces is to a certain extent a con-
ductor of electricity yet a few inches of length present so much resistance that
practically there is no material loss of electricity by conduction through the water.
The positive terminal A may to a certain extent be cooled by water as shewn in the
-section-Fig.-7. The carbon disc A is clamped between the metal collars on a tubular
axis through which water may be made to flow, keeping the metal-cool. Practically,
however, when the disc is of considerable size the air circulating freely around it
suffices to keep it at a moderate temperature without having recourse to cooling by.
water.
Having thus described the nature of my Invention, and in what manner the same
is to be performed, I claim in respect of electric lamps,-
First. The use of a hollow metal terminal kept cool by the passage of water
through its interior, substantially as herein described.
Second. In combination with a terminal such as is referred to in the preceding
claim a cistern so balanced that when it is charged with water flowing from the
terminal it causes contact to be made whereby the lamp is brought into the electric
circuit, but when the water supply ceases it causes contact to be broken, substan-
tially as and for the purposes herein set forth.
Third. The combination of a hollow metal negative terminal cooled by passage of
water through it with a positive terminal consisting of a carbon disc caused to
rotate and advance towards the negative terminal as it is consumed, substantially as
herein described.
In witness whereof, I, the said Charles William Siemens, have hereunto set
my hand and scal, this Twenty-first day of April, in the year of our Lord
One thousand eight hundred and seventy-nine.
C. WILLIAM SIEMENS.
(L.S.)