Year: 1887

page_text: Date of Application, 5th Sept., 1887
Complete Left, 14th May, 1888
Complete Accepted, 20th July, 1888
I, WILHELM LÖNHOLDT, of Berlin, Kingdom of Prussia, architect, do hereby declare
the nature of this invention to be as follows:-
This invention relates to incandescent electric lamps and more especially to the globe
or casing for enclosing the carbon or other incandescent filament and its object is to
allow renewal of said filament without damaging the globe or casing. For this purpose
the invention consists in composing the filament-casing of two pieces so combined one
with the other as to permit of being separated and put together again so that
the lamp can as often as may be desired be provided with a new incandescent
filament.
The two pieces constituting the improved filament-casing can be made of different
material and thus employed as means to adapt the light to special conditions of lighting
and to better utilize the lighting power. Besides, this mode of constructing the
filament-casing rather reduces than augments the expences for mounting and main-
taining the lamp as compared with the lamps now in the market.
Preferably the casing consists of two watch-glass-like shaped pieces or disks united
at their edges. The front or lighting disk can be made of clear, alabastor or frosted
glass, or of dioptric glass or of any appropriate translucent or transparent material.
The back disk may be provided with a reflecting coating. In some cases only one of
the two disks has a watch-glass-like shape whilst the other one is plane.
The edge of either disk has a smooth surface either plane or somewhat conical, or
it is provided with a groove. Upon this edge is applied a proper cement prior to
putting the two disks together. I prefer to employ for this purpose a cement prepared
from mastic, ether, and castor oil. This cement has the property of being both
transparent and elastic, so that it will follow the small expansions and contractions of
the filament-casing without prejudicing the tightness of the joint.
The incandescent filament, which may be bent circularly or spirally or curved in
any other suitable manner is fixed to platina-wires the other ends of which are to be
connected with the conducting wires. Said platina wires are held in a socket to be
inserted into a tubular projection formed or fixed in the centre of the back piece or in
the periphery of the same.

page_text: The socket with the filament connected thereto having been inserted in the back
disk and the two disks cemented together, the casing thus formed is evacuated in the
usual manner. The pressure of the atmospheric air will be of sufficient strength to
maintain the vacuum within the casing. On the other hand the two parts of the
casing can easily be separated by placing the lamp for some time into a hot water
bath.
When the filament is worn out or damaged from any cause, the improved lamp can
easily be repaired by opening the casing as described, removing the filament, inserting
a new one and closing and evacuating the casing again, whereupon the lamp is ready
for further use.
The described construction of the filament-casing is a feature never known as yet
in any incandescent electric lamp and is of great technical and commercial value.
Dated this 2nd day of September 1887.
WILHELM LÖNHOLDT.
By his Agent, Carl Pieper.
Haseltine, Lake & Co.,
45, Southampton Buildings,
London, W.C.

page_text: I, WILHELM LÖNHOLDT, of Berlin, Kingdom of Prussia, architect, 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 specification :-
This invention relates to incandescent electric lamps and more especially to the
globe or casing for enclosing the carbon or other incandescent filament and its object
is to allow the renewal of said filament without damage to the globe or casing. For
this purpose the invention consists in composing the filament-casing of two pieces so
combined together as to permit of their being separated and put together again,
so that the lamp can be provided with a new incandescent filament as often as may be
desired.
The two pieces constituting the improved filament-casing may be made of different
material and thus employed as means to adapt the light produced by the electric
current, to special conditions of lighting and to better utilize its lighting power.
Besides, this mode of constructing the filament-casing rather reduces than augments
the expenses for mounting and maintaining the lamp as compared with the lamps now
in the market.
And in order that this invention may be fully understood I have represented on the
annexed sheet of drawings some examples of the filament-casing constructed as
stated.
As shown in Figs. 1 to 3 the filament-casing consists of two watch-glass shaped
pieces or disks a and b. a is the front piece or lighting disk which may be made of
clear alabastor or frosted glass, as supposed in Fig. 1, or of dioptric glass, as in the
arrangements Figs. 2 and 3, or of any appropriate translucent or transparent material,
such as mica and the like. 6 is the back disk, which may be provided with a reflecting
coating, as in Figs. 1 and 2, or composed of dioptric glass, as supposed in the arrange
ment Fig. 3, or be made of porcelain, jet, ebonite or any other suitable material.
Figs. 4 to 6 represent plans of the above mentioned filament-casings. The bottom
half of Fig. 5 shows on the left hand side the interior surface a of the dioptric front
disk and on the right hand side the exterior surface a¹ of the same.
In the arrange-
ment represented by Fig. 7 only one of the two disks has watch-glass shape, whilst
the other one is plane, and this arrangement of parts may be used in all cases provided
the former disk be made deeper in proportion.
The edges e of the disks have a smooth surface which may be plane as in Fig. 1 or
somewhat conical, or they are provided with rebates as in Figs. 2 and 3. Upon these
edges is applied a suitable cement antecedently to putting the two parts together.
I prefer to employ for this purpose a cement prepared from the following ingredients:
nine parts of gum mastic, twenty parts of ether, and one part of castor oil. This
cement has the property of being both transparent and elastic, so that it will easily
follow the small expansions and contractions of the filament casing without prejudicing
the tightness of the joint.

page_text: с
The incandescent filament c which may be bent circularly or spirally or curved in
any other suitable form, is fixed to platina wires the other ends of which are to be
connected with the conducting wires. Said platina wires are held in a plug d to be
inserted into a tubular projection formed or fixed on the central part of the back
disk b, or on the periphery of the same.
The plug d with the filament connected thereto, having been inserted in the disk b,
and the two disks cemented together, the casing or lamp thus formed is evacuated in
the usual manner, the connection with the air-pump being made for instance by means
of a small tube passed through the plug d and ultimately sealed. In consequence
of the evacuation the disks are pressed together sufficiently by the atmospheric pressure
so that the vacuum will be maintained in the casing. On the other hand the disks
can easily be separated by placing the lamp for some time into a hot water bath.
The construction of the filament-casing out of two parts as described, and the
possibility arising therefrom of separating these parts at will, is a feature as yet
unknown in incandescent electric lamps and is of great technical and commercial
value. Whereas, when the incandescent filament has been worn out or become
injured from any cause or detached from the platina wires, the incandescent lamps
now in the market cannot be restored to lighting condition owing to the inaccessibility
of the interior of the globes, the improved lamp can, when the filament is damaged or
worn, be repaired by opening the casing as described, removing the worn out or
damaged filament, inserting a new one, and closing and evacuating the casing again,
the lamp being then again ready for use. Moreover, whilst the globes as heretofore
used with incandescent electric lamps, can never be made exactly uniform in shape
and size, owing to the said globes being produced by blowing, the casings constructed
as described, are adapted to be manufactured in any desired number of exactly the
same shape and size so that either of the two pieces or disks may be replaced by another
one. Besides the improved filament-casing allows of most advantageously mounting
the lamp. The watch-like form permits the artistic adaptation of any number of lamps
to any style of decoration on the walls or ceiling of the apartment and the lamps may
be fixed without the use of special brackets, crowns, lustres, and the like, a considerable
saving on the first outlay being thereby effected.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is :
A casing for electric light consisting of two pieces or disks (such as a and b) united
at their edges by means of a suitable cement, and one of which is provided with a
tubular branch having inserted thereinto a plug through which the conducting wires
are passed, substantially as described.
Dotad the Toralfth dove at Mr... 1000
CARL PIEPER,
Agent for Applicant.