IMPROVEMENTS IN ELECTRIC LAMPS OR LIGHTING APPARATUS
Year: 1881

page_text: LETTERS PATENT to William Robert Lake, of the Firm of Haseltine, Lake,
& Co., Patent Agents, Southampton Buildings, London, for an Invention of
"IMPROVEMENTS IN ELECTRIC LAMPS OR LIGHTING APPARATUS." A commu-
nication from abroad by Charles Ferdinand de la Roche, of Paris, France.
PROVISIONAL SPECIFICATION left by the said William Robert Lake at
the Office of the Commissioners of Patents on the 14th December 1881.
WILLIAM ROBERT LAKE of the Firm of Haseltine, Lake, & Co. Patent Agents,
Southampton Buildings, London. "IMPROVEMENTS IN ELECTRIC LAMPS OR
LIGHTING APPARATUS." [A communication from abroad by Charles Ferdinand
de la Roche, of Paris, France.]
This Invention relates to improvements in electric lamps or lighting apparatus.
According to the said Invention I develop the voltaic arc in the interior of a
chamber or space provided in a block of any kind of refractory material, having in
its walls or sides, openings in the form of the frustrum of a cone so as to allow the
light produced to emerge in determined directions.
Heretofore it has not been possible to obtain a complete steadiness of the voltaic
arc, it being continually disturbed by the action of the currents of air around it,
either above or below the points of the electrodes, the variation of the temperature
and conductibility of which modify the brilliancy of the light produced; these
variations, combined with the vibrations produced by the air, cause the disagreeable
flickering which generally characterises the electric light. This continuous
disturbance of the voltaic arc alters also its shape; moreover these continuous
variations, and, if it may be so called, the rapid mixture of the different rays of the
electric spectrum, change every instant the steadiness, and the color of the light and
produce the flickering. Moreover the partial cooling of the points frequently causes
a rapid consumption of the electrodes, which split and break.
According to the present Invention these difficulties are overcome by protecting
the voltaic are from the motion of the surrounding air; I enclose the extremities

page_text: of the electrodes within a refractory chamber, the forms and dimensions of which
vary necessarily, with the diameter, the shape, and the position of the said
electrodes.
This chamber can be prepared within a block of any refractory material such as
magnesia, zircon, platinum or the like, but the material I prefer to use is calcined
magnesia, chemically pure and compressed in moulds by means of a hydraulic press.
For electrodes of seven millimetres in diameter, it is sufficient to use blocks the
width of whose sides is from 3 to 4 centimetres and which are 2 centimetres in
thickness. These blocks are fixed in a sheet of metal such as platinum, copper, or
steel and are hollowed out in the direction of the luminous projections which
permits the block to be used during several days even if split after having been
used for some time; their consumption is in fact scarcely perceptible, as their sides
are not directly struck by the electric arc and their temperature, although very
high, is not sufficiently bigh to injure the pure magnesia. On the contrary, if the
electrodes are made to rest on refractory seats, the latter become rapidly dete-
riorated by the action of the potash and the silica contained in the carbons and by
the natural perforating power of the are; moreover the points of the electrodes
become covered with a light layer of silica, which disturbs the arc or extinguishes
the lamp.
The internal sides_of_the_chamber_reach_a_white_heat through the heat given out
by the voltaic arc and become incandescent so that the luminous rays, thus produced
unite with those of the arc, increase its intensity by forming a luminous sheet of
an intense white having a tendency to a gold yellowish color instead of the
ordinary pale colour of the voltaic arc. Under these conditions, the variations of
the light produced through the modifications caused to the current, by the change
in the speed of the dynamo-electric machines, are no longer appreciable to the eye,
as they occur in a centre of greater brilliancy than their normal coloration. On the
other hand, and this is one of the principal advantages resulting from the appli-
cation of this Invention, the intense heat produced in the chamber causes a
considerable dilatation of the air contained in it, which greatly increases the size
of the voltaic arc which then not only fills the whole chamber but also a part of
its conical openings; and the whole block becoming incandescent there is really a
combination of the incandescent light and the voltaic arc which forms the luminous
sheet of a beautiful tint and of absolute steadiness.
I may place upon the hollows or openings of the blocks fine blades of mica or of
any other refractory translucid material preventing the surrounding air from
touching the electrodes; in this case the temperature of the air contained in the
chamber is still higher, which increases the dimensions of the voltaic arc in a
considerable proportion. This is a very important result of the application of my
Invention. This addition of the blades of mica is not indispensable to the
effectiveness of the apparatus, nor for the steadiness of the arc; I use it therefore
only in certain determined cases. The chambers for the electrodes may be made of
transparent material for example six thin plates of mica mounted upon sheets of
platina, provided with holes for the free passage of the electrodes.
In this, as well as in the preceding case, the voltaic arc is protected from the currents
of air, while the high temperature contained in the chamber drives off the molecules
and thus secures the increase in the size of the arc produced; under these conditions
the chamber could be, if necessary, of larger sizes, than those indicated, and could for
example be made of glass or other substance more refractory, but transparent. In
any case, the block is suspended by means of one or more adjustable rods allowing
it to be placed exactly in the axis of the electrodes, thus preventing any friction
affecting the advance of the carbons.
In one form of my Invention the conical openings give passage to the luminous
rays in two opposite directions, the refractory block is formed of two pieces, kept
one exactly in front of the other, by two frames which can be drawn closer, by a
screw, and which bear metallic plates serving to prevent the separation of fragments
from the block if it gets split through use. Moreover the top plate is provided with

page_text: a screw-threaded socket serving to fix the block and to regulate its position inside
the lamp.
In a modification the block is provided with four conical openings, for the free
passage of the luminous rays; this block like the former one, is also provided with
inetallic frames.
In another modification the refractory block is provided with only one conical
opening, permitting the luminous rays to travel in one direction only, and if
desired a reflector may be used from which they can then be diffused in the
direction desired.
My Invention being applicable to any kind of electric lamps actually in use, it
can also be employed in connection with all systems for the arrangement of the
carbons which may be placed in horizontal, vertical, or oblique directions; moreover
it can also be employed with converging lenses or reflectors of any form and
dimension, according to the nature of the application required.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said William Robert Lake in the Great Seal Patent Offico on the
14th June 1882.
WILLIAM ROBERT LAKE of the Firm of Haseltine Lake & Co., Patent Agents,
Southampton Buildings, London. "IMPROVEMENTS IN ELECTRIC LAMPS OR
LIGHTING APPARATUS." A communication from abroad by Charles Ferdinand
de la Roche of Paris, France.
-
This Invention relates to improvements in electric lamps or lighting apparatus.
According to the said Invention I develope the voltaic arc in the interior of a
chamber or space provided in a block of any suitable refractory material, having in
its walls or sides, openings in the form of the frustum of a cone, so as to allow the
light produced to emerge in determined directions.
Heretofore-it-has-not-been-possible-to-obtain-a-complete steadiness of the voltaic
arc, it being continually disturbed by the action of the currents of air around it,
either above or below the points of the electrodes, the variations in the temperature
and conductibility of which modify the brilliancy of the light produced; these
variations combined with the vibrations produced by the air cause the disagreeable
flickering which generally characterizes the electric arc-light. This continuous
disturbance of the voltaic are also alters its shape, moreover these continuous
variations, and if it may be so called the rapid mixture of the different rays of the
electric spectrumn change every instant the steadiness and the colour of the light
and produce the flickering.
Furthermore the partial cooling of the points frequently causes a rapid con-
sumption of the electrodes which split and break.
According to the present Invention these difficulties are overcome by protecting
the voltaic are from the motion of the surrounding air; for this purpose I enclose
the extremities of the electrodes within a refractory chamber the form and
dimensions of which necessarily vary according to the diameter, shape and position
of the said electrodes. This chamber can be formed within a block of any
refractory material such as magnesia, zircon, platinum or the like, but the material
I prefer to use is calcined magnesia chemically pure and compressed in moulds by
means of a hydraulic press. For electrodes of seven millimetres in diameter it is
sufficient to use blocks which have sides of from three to four centimetres and
which are two centimetres in thickness. These blocks are fixed in a sheet of metal
such as platinum, copper or steel and are hollowed out in the direction it is desired
to give to the luminous rays, this arrangement permits the block to be used during
several days even if cracked or split after having been used for some time; the
consumption of the blocks is in fact scarcely perceptible as their sides are not
directly in contact with the electric arc and their temperature although very high
is not sufficiently high to injure the pure magnesia. On the contrary if the
electrodes are made to rest on refractory supports the latter become rapidly
deteriorated by the action of the potash and the silica contained in the carbons
and by the natural perforating power of the arc; moreover the points of the
electrodes become covered with a slight layer of silica which disturbs the arc or
extinguishes the lamp.
The internal sides of the chamber reach a white heat, through the heat given out
by the voltaic arc and become incandescent so that the luminous rays, thus pro-
duced, unite with those of the arc and increase its intensity by forming a luminous
sheet of an intense white having a tendency to a gold yellowish colour, instead of
the ordinary pale colour of the voltaic arc.

page_text: Under these conditions, the. variations of the light produced through the modifi-
cations caused in the current by the change in the speed of the dynamo-electric
machines, are no longer appreciable to the eye, as they occur in a centre of greater
brilliancy than their normal colouration. On the other hand, and this is one of
the principal advantages resulting from the application of this Invention, the
intense heat produced in the chamber causes a considerable dilatation of the air
contained in it, which greatly increases the size of the voltaic are which then not
only fills the whole chamber but also part of its conical openings and the whole
block becoming incandescent it is in reality the light produced by incandescence
combined with that produced by the voltaic arc, which forms the luminous sheet
of a beautiful tint and of absolute steadiness.
I may place upon the hollows or openings of the blocks thin plates or sheets of
mica or of any other refractory translucid material to prevent the surrounding air
from touching the electrodes; in this case the temperature of the air contained in
the chamber is still higher, which increases the dimensions of the voltaic arc in a
considerable proportion. This is a very important result of the application of my
Invention. This addition of the plates of mica is not indispensable to the effectiveness
of the apparatus nor for the steadiness of the arc, I use it therefore only in certain
determined cases.
The chambers for the electrodes may be made of transparent material, for
example, six thin plates of mica may be mounted upon sheets of platinum provided
with holes for the free passage of the electrodes.
In this as well as in the preceding case the voltaic arc is protected from the
currents of air, while the high temperature of the air contained in the chamber
separates the molecules and thus ensures the increase of the size of the arc pro-
duced; under these conditions the chamber could be if necessary of larger size
than those indicated, and could, for example, be made of glass or other substance
more refractory, but transparent.
In any case the block is suspended by means of one or more adjustable rods
allowing it to be placed exactly in the axis of the electrodes, thus preventing any
friction affecting the advance of the carbons.
In the accompanying Drawing are represented different forms of refractory
blocks made according to the said Invention.
In Figures 1, 2, 3, 4, 5 the chamber which receives the extremities of the
electrodes and the conical openings which give passage to the luminous rays in
two opposite directions are formed in the refractory block, which is in two pieces,
kept one exactly in front of the other, by two frames which can be drawn closer
by means of the screws c, which also support the metallic plates serving to prevent
the separation of the fragments from the block, when it gets split through use.
Moreover the top plate is provided with a screw-threaded socket serving to fix the
block and to regulate its position inside the lamp.
In the modification represented in Figures 6 and 7 the block is provided with
four conical openings for the free passage of the luminous rays; this block like the
former one, is also provided with metallic frames.
In another modification represented in Figure 8 the refractory block a is pro-
vided with only one conical opening permitting the luminous rays to travel in one
direction only and if desired, a reflector may be used from which they can then
be diffused in any direction.
The said Invention being applicable to any kind of electric lamp actually in use
can also be employed in connection with all systems for the arrangement of the
carbons which may be placed in horizontal, vertical or oblique directions moreover
it can also be employed with converging lenses or reflectors of any form and size,
according to the nature of the application required.
Having thus fully described the said Invention as communicated to me by my
foreign correspondent, and the manner of performing the same, I wish it under-
stood that I claim
First For an electric lamp or lighting apparatus, the chamber composed of a

page_text: block of refractory material hollowed out in the manner herein described and
represented in the accompanying Drawing; and surrounding the voltaic are in
order to protect it against external currents of air and to considerably raise the
temperature of the centre in which the arc is produced, substantially as set
forth.
Second The walls of the said chamber provided with plates of mica or other
refractory transparent material, or constructed entirely of plates of mica to protect
the voltaic arc from the action of the external air and to raise, to a very high
degree, the temperature of the air in which the arc is produced, substantially as
set forth.
Third The block of refractory material constructed to permit the passage of
the luminous rays from the voltaic arc, substantially as shewn in either of the
Figures of the accompanying Drawing.
In witness whereof I the said William Robert Lake have hereunto set my
hand and seal this Fourteenth day of June in the year of our Lord One
thousand eight hundred and eighty two.
W. KUB. LAKE. (L.S.)