IMPROVEMENTS IN THE CONSTRUCTION OF LAMPS FOR MAGIC LANTERNS AND OTHER PURPOSES
Year: 1879

page_text: LETTERS PATENT to George Smith, of Great Portland Street, in the County of
Middlesex, for the Invention of "IMPROVEMENTS IN THE CONSTRUCTION OF
LAMPS FOR MAGIC LANTERNS AND OTHER PURPOSES."
Sealed the 2nd April 1880, and dated the 3rd October 1879.
"
PPROVISIONAL SPECIFICATION left by the said George Smith at the Office
of the Commissioners of Patents on the 3rd October 1879.
GEORGE SMITH, of Great Portland Street, in the County of Middlesex.
IMPROVEMENTS IN THE CONSTRUCTION OF LAMPS FOR MAGIC LANTERNS AND
OTHER PURPOSES."
My Invention relates more especially to lamps used for the purpose of obtaining
light for magic lanterns, but it is also applicable to lamps used for other purposes,
such as signalling on railways or on board ships.
It has for its objects improved methods of constructing the flame chamber of the
lamp or the chamber in which the flame burns from which the light is obtained,
and also improved methods of increasing the amount of light utilized from such
flame. My improvements are especially applicable to lamps burning mineral oil,
but they may also be applied to lamps burning other oils or gas.
The flaine chamber in such lamps, as heretofore ordinarily inade, is provided with
suitable apertures for regulating the supply of air to the flame and carrying off the
products of combustion, and it is made of sheet iron or other metal, having its two
ends quite open, but closed when the lamp is in use by plates of glass somewhat
larger than the openings, and kept in their places by clips or springs. It has been
found that in lamps so constructed these plates of glass are liable to break from
becoming unequally heated, their outer edges remaining comparatively cool, and
currents of cold air rushing between them and the ends of the chamber.
Also that such currents of air affect the steadiness of the flame.
The first part of my Invention consists in novel methods of constructing the
flame chamber so that the glass ends fit closely, and are less liable to be broken by
the heat.

page_text: I make the flame chamber cylindrical in end view, and I close its ends by circular
plates of glass, talc, or other sufficiently transparent material fitted into cells
formed or fitted upon the ends of the cylindrical chamber, and the same diameter
as the latter.
The glass plates being somewhat less in diameter therefore than the cylinder
become equally heated, and are little liable to break, whilst the ends of the cylinder
being accurately closed currents of cold air cannot pass between them and the glass
plates. I prefer to make the cylindrical cells in which the circular glass plates are
fitted so that they enter the cylinders for a short distance, and are then provided
with narrow flanges, against which the glass plates rest, and are held by wires
sprung into their places by screws or by other equivalent means.
By this method of construction the plates are not only less liable to break, but if
one cracks in consequence of the heat the pieces are prevented from falling out, and
the light is not so materially affected as in the case of ordinary lamps.
Flat plates of glass may be used for the purpose described, but I prefer to make
them concave, more especially for the purpose of closing the back end of the flame
chamber. I place such plates in their cells with their convex side outward, and
upon the plate at the back end I deposit upon such outer side a coating of silver by
one of the ordinary well known methods, the silver acting as a reflecting surface,
whilst if of the proper thickness it is sufficiently transparent to allow the flame to
be examined for the purpose of adjusting and regulating it.
In order to increase the whiteness of the flame in such lamps I sometimes
adjust and fix in the flame one or more wires or thin plates of platinum or other
metal not easily fused.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said George Smith in the Great Seal Patent Office on the 3rd April
1880.
GEORGE SMITH, of Great Portland Street, in the County of Middlesex.
"IMPROVEMENTS IN THE CONSTRUCTION OF LAMPS FOR MAGIC LANTERNS AND
OTHER PURPOSES."
This Invention relates more especially to lamps used for the purpose of obtaining
light for magic lanterns, but it is also applicable to lamps used for other purposes,
such as signalling on railways or on board ships.
It has for its objects improved methods of constructing and arranging and fixing
the several parts of the flaine chambers of the lamp, that is to say, the chamber in
which the flame burns from which the light is derived, and also improved methods
of increasing the amount of light utilized from such flame. My improvements are
especially applicable to lamps burning mineral oil, but they may also be applied to
lamps burning other oils or inflammable liquids or gas. In such lamps, as heretofore
ordinarily made, the flame chamber is provided with suitable apertures for regulating
the supply of air to the flame and carrying off the products of combustion, and it is
made of sheet iron or other metal, having its two ends quite open, but closed when
the lamp is in use by plates of glass somewhat larger than the openings, kept in
their places against the ends of the chamber by clips or springs. It has been found
however that in lamps so constructed these glass plates are liable to break from
becoming unequally heated, their outer edges remaining comparatively cool and
being exposed to currents of cold air rushing between them and the ends of the
chamber; also that such currents of air affect the steadiness of the flaine. The first
part of my present Invention consists in novel methods of constructing the Game
chamber so that the glass plates which form its ends fit closely, and are less liable
to be broken by the heat. I make the flame chamber cylindrical in end view, and
I close its ends by circular plates of glass, talc, or other sufficiently transparent
material fitted into cells formed or fitted upon the ends of the cylindrical chamber,
and of nearly the same diameter as the latter. The glass plates being somewhat
less in diameter therefore than the cylinder become equally heated, and are little
liable to break, whilst the ends of the cylinder being sufficiently accurately closed
currents of cold air cannot pass between them and the edges of the glass plates. I
prefer to make the cylindrical cells in which the circular glass plates are fitted in
such manner that they enter the cylinder for a short distance, and are then provided
with narrow flanges against which the glass plates rest, and are held in position by
wires or rings sprung into their places outside the plates, or by screws or other
equivalent means. By this method of construction the plates are not only less
liable to break, but if one of them becomes cracked in consequence of the heat the
pieces are prevented from falling out, and the light is not so imaterially affected as
in the case or ordinary lamps, where the pieces are liable to fall entirely away.
Flat plates of glass may be used for the purpose described, but I prefer to make
them concave, more especially the one used for the purpose of closing the back end
of the flame chamber. I place such plates in their cells with their convex side
outward, and upon the plate at the back end I deposit upon such outer side a thin
coating of silver by any of the ordinary well known methods, the silver acting as a
reflecting surface, whilst if thin enough it is sufficiently transparent to allow the
flame to be examined through it for the purpose of adjustment and regulation. In
order to increase the whiteness of the flame in such lamps I sometimes adjust and
fix in the flame one or more wires or thin plates of platinum or other metal not
easily fused.
The accompanying Drawing is in illustration of my Invention. Figure 1 is a
longitudinal section of a lamp constructed according to my Invention; Figure 2 is

page_text: .
a transverse section; Figure 3 is a side view of the flame chamber and lamp; and
Figure 4 is a side view of the flame chamber removed from the lamp. A is the
cylindrical metal flame chamber, hinged at E to the upper part of the lamp B,
which is shewn having two adjustable wicks at C and D. The lower part of the
chamber A is provided with a suitable opening and perforated metal guards for the
flame from the lamp B, and its upper part is provided with an opening at F for
the moveable adjustible chimney G. The front and back ends of the cylindrical
flame chamber A are provided with cells at H and I, into the front one of which at
Hfits the circular plate of flat glass K, whilst into the back one at I fits the circular
concave glass L. The glasses K and L are retained in their position by flanged
rings fitted into the cells above the glass plates, as shewn. The circular concave
glass plate L is coated with silver so as to serve as a reflector, but the coating is
sufficiently thin to allow the flame to be seen through it for the purpose of adjust-
ment. In Figures 1 and 2 the outer lantern and lenses are shewn in dotted lines.
Having now described my Invention, and the manner in which it is to be
performed, I claim, the method of fitting and fixing circular, flat, or concave trans-
parent plates in cells in the ends of the flame chamber of lanterns, substantially
as described and shewn in the Drawing. Also, the concave glass reflectors, so fitted
into a cell at the end of such flaine chamber, and coated with a film of silver
sufficiently thin to be transparent, substantially as and for the
described.
purpose
Also, the introduction of metal wires or plates not easily fusible into the flame, for
the purpose of increasing the light from such lanterns.
In witness whereof, I, the said George Smith, have hereunto set my hand and
seal, this Third day of April, in the year of our Lord 1880.
CHODOWE