IMPROVEMENTS IN ELECTRIC INCANDESCENT LIGHTING APPARATUS
Year: 1882

page_text: LETTERS PATENT to Richard Werdermann of Princes Street in the County of
Surrey, Civil Engineer, for an invention of "IMPROVEMENTS IN ELECTRIC
INCANDESCENT LIGHTING APPARATUS"
PROVISIONAL SPECIFICATION left by the said Richard Werdermann at
the Office of the Commissioners of Patents on the 25th March 1882.
RICHARD WERDERMANN, of Princes Street, in the County of Surrey, Civil
Engineer "IMPROVEMENTS IN ELECTRIC INCANDESCENT LIGHTING APPARATUS
دو
My Invention relates to apparatus for the production of incandescent light by
clectricity.
In order that my said Invention may be fully understood I wish to make the
following preliminary remarks on what is termed incandescent light, and the
disadvantages inherent to the same.
Electric lamps for incandescent lighting are generally provided with a fine carbon
filament of high electrical resistance placed in a glass bulb from which the air has
been exhausted, the ends of the said carbon filament being connected with platinum
or other wire leading to the terminals through which the electric current is conveyed
to the carbon filament.
The production of the vacuum in the bulb is a difficult task and causes the
greatest part of the expense incurred in the manufacture of these lamps. Morcover
an absolute or perfect vacuum cannot be obtained therein.
A further disadvantage of the carbon filament is the smallness of the
amount of light which can be obtained from it, as it cannot, in practice, be
raised to incandescence or a white heat because of the volatilization of the carbon
which would occur at such a high temperature. The intensity of the electric
currents employed for the production of the light must therefore be invariable as
the lamp will be very quickly destroyed if the electric current increases too much.
For this reason such lamps cannot be worked in series, as the extinction of one
lamp will break the circuit and all other lamps in the same circuit will be
extinguished at the same time.

page_text: All of these difficulties are overcome in my improved lamp which is constructed
as follows, that is to say:-
A carbon pencil is kept in contact with a carbon or metal electrodo of larger
cross sectional area, either by springs, by a weight, or by liquid pressure.
This carbon pencil, as well as the contact-devices, are enclosed in a tube which
is hermetically closed at one end; Its other end is covered by a disc provided with
a central aperture through which the carbon pencil projects into a cylinder or globe
of glass which is screwed air tight upon the said tube, and the top of which is
closed by the other carbon or metal electrode. This electrode is connected with
one pole of the source of electricity, the carbon pencil being connected by suitable
means to the other pole.
In order to prevent the incandescence of the carbon pencil below. or beyond the
desired distance from its point of contact with the other electrode the same is
provided with a collar of magnesia, steatite or other suitable material through
which it can slide freely, the said collar being fixed upon the disc by which the
tube is covered as above specified.
Now when the part of the carbon pencil.comprised between the collar and the
point of contact with the other electrode is heated to incandescence by the passage
of the electric current, the small amount of oxygen in the lamp is soon consumed
and the atmosphere of nitrogen carbonic acid, and carbonic oxide then contained
in the same does not affect the carbon and no further oxidation takes place.
These lamps may be worked in parallel circuits or they may be placed in series
without danger of breaking the carbon pencil even with a variable current. Each
lamp may be provided with a circuit closer which, when the carbon is entirely
consumed, will prevent the breaking of the circuit; and an artificial resistance may
be used in connection with the said lamp to permit one or several lamps in the
same circuit to be extinguished without altering the intensity of the remaining
lights.

page_text: *SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Richard Werdermann in the Great Seal Patent Office on the
25th September 1882.
RICHARD WERDERMANN, of Princes Street, in the County of Surrey, Civil
Engineer, "IMPROVEMENTS IN ELECTRIC INCANDESCENT LIGHTING APPARATUS"
My Invention relates to apparatus for the production of incandescent light by
electricity.
In order that my said invention may be fully understood I make the following
preliminary remarks on what is termed incandescent light and the disadvantages
inherent to the same.
Electric lamps for incandescent lighting are generally provided with a fine carbon
filament of high résistance placed in a glass bulb from which the air has been
exhausted, the ends of the said carbon filament being connected with platinum or
other wire, leading to the terminals of the lamps, through which the electric current
. is conveyed to the carbon filament.
The production of the vacuum in the bulb is a difficult task, and causes the
greatest part of the expense incurred in the manufacture of these lamps. Moreover
an absolute or perfect vacuum cannot be obtained therein.
A further disadvantage attending the use of a carbon filament is the smallness
of the amount of light which can be obtained therefrom, as it cannot in practice
be raised to true incandescence or a white heat because of the volatilization of the
carbon which would occur at such a high temperature. And the intensity of the
electric current employed for the production of the light must, therefore, not only
be carefully proportioned to the endurance of the lamp, but must be invariable as
the lamp will be very quickly destroyed by any great increase of the current. For
this reason such lamps cannot be worked in series, as the extinction of one lamp
will break the circuit, and all other lamps in the same circuit will be extinguished
at the same time.
All of these difficulties are overcome in my improved lamp, which is constructed
as shown in the accompanying drawing, and which I will now proceed to particularly
describe.
In the said drawing I have shown in Figure 1 a vertical transverse section of
one form or modification of my invention, and in Figures 2 and 3 an elevation and
a vertical section on the line x, x, of another modification thereof.
In these lamps a carbon pencil electrode a is kept in contact with a carbon or
metal electrode b (of larger cross sectional area than the pencil a) either by springs,
by a weight, or by liquid pressure. This carbon pencil is supported and enclosed
in a tube which is, in some instances, hermetically closed at one end. Its other.
end has a disc provided with a central aperture through which the carbon pencil a
projects into a cylinder or globe of glass which is screwed air tight upon the said
tube and which contains the other carbon or metal electrode b. This electrode is
connected with one pole of the source of electricity, the carbon pencil being
connected by suitable means to the other polo.
In the lamp shown in Figure 1, I make use of liquid pressure to keep the carbon
pencil à in contact with the electrode b. For this purpose I construct the said
lamp with a tube or cylinder c which I fill with mercury, glycerine, or other
suitable liquid; d is a disc or plate which closes this tube c at its upper end.
To prevent incandescence of the carbon pencil a below, or beyond, the desired
distance from its point a* which is in contact with the other electrode b, I fix on
the disc da collar e of steatite, magnesia, or other material capable of enduring
the heat caused by the incandescence of the carbon. This collar is so fitted to the
pencil a that the latter can slide freely through the same, but the collar will absorb
so much of the heat as to prevent the incandescence of the carbon below the said

page_text: .
collar. The disc d has a rim as shown, or other suitable provision, for the
reception of the glass cylinder f which is hermetically closed at its upper end by
the carbon or other block forming the electrode b, and at its lower end by the
liquid in the tube c. g, h, are the terminals; the terminal / is secured to the rod i
which is connected with the electrode b, this rod being insulated at its lower end
by a plate or piece j of any suitable material. Assuming that g is the positive
terminal, the direction of the current will be from this terminal through the liquid
to the electrode a, and froin the latter, through the electrode b and the rod i, to
the terminal h.
When the part of the carbon pencil comprised between the collare and the
point of contact with the other electrode is heated to incandescence by the passage
of the electric current, the small amount of oxygen in the lamp is soon consumed
and the atmosphere of nitrogen, carbonic acid, and carbonic oxide, then contained
in the same does not affect the carbon and no further oxidation takes place.
In the modification of my invention illustrated in Figures 2 and 3, is a tube
through which the pencil or electrode a extends into the globe f¹; is a metal rod
or wire which carries the fixed electrode b at its upper end. The electrode a is
kept in contact with the electrode b by means of a spring m enclosed in the tube k,
the latter being provided at its lower end with a screw cap or similar device to
permit access to, and regulation of, the said spring. The disc forms a base or
holder for the globe which is secured hermetically tight thereto. On this disc
I fix a bracket, or pair of brackets, n for carrying the small metal grooved guido
rollers o between which the pencil a is held and moves. The terminal g is fixed
in the disc k¹ and the end of the rod (which extends through the disc and is
insulated therefrom) forms the other terminal h.
These lamps may be worked in parallel circuits, or they may be placed in series,
without danger of breaking the carbon pencil, even with a variable current. Each
lamp may be provided with an automatic or other circuit-closer, which, when the
carbon is entirely consumed, will prevent the breaking of the circuit, and an
artificial resistance used in connection with the said lamps will permit one or
several lamps in the same circuit to be extinguished without altering the intensity
of the remaining lights.
Having thus fully described my said Invention, and shown how the same may
be conveniently and advantageously carried into practice, I wish it understood that
I do not claim generally the use of an electrode in the form of a pencil or rod, in
combination with another electrode of larger sectional area, nor the use of mercury
or other liquid for keeping the moving electrode in contact with the fixed electrode,
but I claim, in an incandescent electric lamp,
First. The fixed electrode enclosed within an air-tight globe, cylinder, or chamber
(which may or may not have a vacuum therein) and the moving electrode arranged
to be kept in contact with the fixed electrode within the said globe, cylinder, or
chamber, substantially as, and for the purpose, specified.
Second. The combination, with the moving electrode, of the collar or ring of
steatite, magnesia, or other suitable refractory material, substantially, as and for
the purpose, specified.
Third. The combination of parts constituting my improved lamp, substantially
as shown in Figure 1, or in Figures 2 and 3 of the drawing.
In witness whereof I the said Richard Werdermann have hereunto set my
hand and seal this twenty third day of September in the year of our Lord
One thousand eight hundred and eighty two.