Improvements in Incandescent Electric Lamps.
Year: 1893

page_text: Date of Application, 4th Mar., 1593-Accepted, 22nd Apr., 1893
COMPLETE SPECIFICATION.
[Communicated from abroad by TURNER D. BOTTOM, of Hoosick, Rensselaer
County, New York, United States of America.]
Improvements in Incandescent Electric Lamps.
1, OLIVER IMRAY, of No. 28 Southampton Buildings, in the County of London,
Chartered Patent Agent, 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:―
My invention relates to the incandescent body used in incandescent electric lamps.
and to means of connecting it to the external conductors.
The incandescent body usually employed is made of some carbonisable substance,
and is practically homogeneous in section. This answers well for carbons of high
resistance, subject to a comparatively small current, but, when considerable currents
are employed, such carbons, owing to their hardness, do not readily expaud, and
are therefore liable to rupture when subjected to the current.
up of
My foreign correspondent has found that if the incandescent body is made
a number of concentric tubes of carbon, of the same or of different character, it
Such
expands rapidly, and does not break under the influence of large currents.
bodies are therefore especially adapted for lamps whose light ranges from fifty to
two thousand candle power.
It has also been the practice to connect the incandescent body to external
conductors by wires sealed into the glass of the neck or base of the lamp, and,.
in order to prevent rupture of the glass where the wires passed through it, they
were made of conducting material having a coefficient of expansion practically
the same as that of glass. Platinum is the only material which has been success-.
fully used in this manuer. It answers very well for lamps using comparatively
small currents such, for instance, as one-half to four ampères.
The use of platinum, however, is prohibitory for lamps using large currents-
such as from ten to thirty ampères-because it is very expensive, and if the
platinum conductors are made sufficiently large to carry the required current, they
do not become uniformly heated, and hence their coefficient of expansion being no
longer equal to that of glass, they do not perform their office any better than iron
or copper wires would do.
One object of my invention is to provide a simple and ready means for introducing
any quantity of current that may be required into the lamp, and in such a manner
that the stability of the lamp, as a whole, may be maintained.
A further object of my invention is to provide between the leading in wires
and the globe of the lamp, an elastic seal; or, in other words, means for
compensating for any difference of expansion between the leading in wires and
the glass.
Another object of my invention is a construction of lamp such that its base can
be readily removed for the introduction of a new incandescent body, and then
attached to the globe again.
In the accompanying drawings which illustrate my invention similar letters of
reference indicate like parts:
Figures 1 to 8 are vertical sections showing several modified constructions of
lamps according to my invention.
Figure 9 is a sectional plan at the base of Figure 8.
Referring first to Fig. 1: A is a glass bulb having at its lower part two parallel
tubes B B, through which pass the leading in wires C C', which may be made of
iron, copper or other good conducting material, and are connected to the incandescent
body D, which body may be a filament, as commonly used for parallel distribution ;

page_text: or a heavier body, as employed for series distribution, or other known kind of
incandescent body.
The incandescent body, however, which I prefer to use (to which I have given
the name of "Tubulite," as indicating that it is made up of a series of concentric
tubes or layers) consists of successive layers of very soft, or very hard, or very
soft and very hard carbon, so as to give freedom for expansion and contraction,
the soft tubes or layers yielding to the variations of the harder tubes or layers.
To form this incandescent body, I first make a core of soft carbon from a vegetable
fibre, such as flax, bamboo, monkey bass, or other similar body, having parallel fibres,
and treat it, to remove its ligneous matter, and subsequently carbonise it.
Surrounding the core of soft carbon is a shell or tube of hard carbon made by
immersing the soft carbon core in an oil bath and heating it very rapidly to a high
temperature, by the passage of an electric current, thus causing a deposit of fine
granular carbon around the soft core. The body, removed from the oil bath,
washed and dried, is then coated with a mixture composed of lamp black and syrup,
or equivalent material, placed in a muffle or retort, and carbonised to form a second
soft and porous carbon shell or tube, covering the hard tube previously formed.
After this the body is again subjected to the oil bath process, and a second bard
shell is deposited on it. This operation is repeated as often as required to bring the
incandescing body to the required size.
E E are thin discs of platinum sealed respectively to the leading in wires C C¹
and to the glass of the tubes E E'. These discs, being very thin, form an elastic
connection between the leading in wires and the glass of the tubes.
'Fig. 2 represents a similar construction, the base F being made removable. The
lamp is exhausted through the tube G shewn in dotted lines which is sealed, as is
shewn by the full lines, after the exhaustion is completed. The base F may be
sealed into the globe A, in any suitable manner, to make it air-tight.
Fig. 3 shews a construction substantially similar to that shewn in Figs. 1 and 2,
with the tubes B and B made somewhat shorter and a space below to allow for
better cooling at the base of the lamp.
As shewn in Fig. 4, there is secured in the base of the lamp a disc of platinum E,
through which the leading in wires C and Care passed, and sealed thereto by
portions of glass H surrounding them. Thus the platinum disc H is sealed to
glass only, namely, the glass of the globe and the glass pieces H surrounding the
wires.
$
As shewn in Fig. 5, the wires C and C₁ are carried through cups I and I' of
platinum sealed into the glass base of the lamp.
As shewn in Fig. 6, the leading in wires C and C¹ are connected to hollow
cylinders or closed tubes of platinum J and J' sealed into the glass base of the
lamp. If these cylinders are made large enough, they may be made of copper, or
some resilient metal, preferably platinized, so as to make them readily unite withi
the glass.
As shewn in Fig. 7, there is connected to the neck of the lamp by a platinum
solder at K a brass neck piece L helically corrugated. In the bottom of L is
introduced a disc of platinum E insulated by a ring of rubber M from the metal
of L. The one conductor C is carried through the disc E, the other couductor C¹
is connected to the metallic neck L.
In this lamp, when the incandescent body is destroyed, the neck L may be
disconnected from the glass, by melting the platinum solder K.
Figs. 8 and 9 shew two platinum discs E and E' sealed into the neck of the
bulb and the wires C Care soldered to the inner surface of these discs without
passing to the outside.
Then
In the constructions described, the platinum discs or tubes form elastic unions
between the leading in wires and the glass of the bulb. In Fig. 4 though the
discs are not directly united to the leading in wires, the result is the same.
when a current (which may be a current of any quantity, say for instance, a
hundred ampères) is transmitted, causing expansion, the flexibility of the discs or

page_text: cylinders surrounding the leading in wires allows this expansion to take place
without dangerously straining the glass.
The joints or seals between the leading in wires and the glass may vary in many
ways, providing they are of flexible or yielding character.
Materials other than platinum may be used for the purpose, for instance, very
thin discs or cylinders of copper, which may be united to the glass through the
instrumentality of a platinum solder.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. An incandescent body for an electric lamp, consisting of a core surrounded
by concentric tubes of soft and hard carbon, substantially as and for the purpose.
set forth.
2. The herein described method of constructing an incandescent body such as is.
above referred to.
3. In combination with the glass bulb of an incandescent lamp, leading in wires.
carried through the base of the lamp, and a seal connecting them to the glass,.
formed of a resilient metal which will unite with glass, substantially as described.
4. In combination with the glass bulb of an incandescent lamp, a disc or discs or
closed tubes of platinum sealed to the glass and to the leading in wires, substantially
as described.
5. In combination with the glass bulb of an incandescent lamp, a removable-
base of resilient metal, to which the leading in wires are connected, substantially as
described.
Dated this 4th day of March 1893.
ABEL & IMRAY,
Agents for the Applicant..