Improvements in the Glass Chimneys, Globes, and Shades of Electric and other Lamps.
Year: 1892

page_text: Date of Application, 23rd Feb., 1892
Complete Specification Left, 19th Nov., 1892-Accepted, 31st Dec., 1892
PROVISIONAL SPECIFICATION.
Improvements in the Glass Chimneys, Globes, and Shades of Electric
and other Lamps.
I ALBERT CAY, trading as James Stevens and Son and also as Stone, Fawdry
and Stone, of Dartmouth Street, Birmingham in the County of Warwick, Glass
Manufacturer, do hereby declare the nature of this invention to be as follows:-
In electric and other lamps where the incandescent arc or filament or flame has
so intense a luminosity as to be distressing to the eye the light is sometimes diffused
by the use of a chimney, globe or shade made of opalescent or semi-transparent glass
or of transparent glass roughened on one of its surfaces.
In these methods of diffusing the light there is a considerable loss of light. This
is undesirable and the object of my invention is so to diffuse the light as to prevent
pain to the eye, and at the same time to avoid any loss of light.
My said invention consists in introducing into the glass of which the chimney,
globe or shade is made, grains of colourless sand or particles of glass having a
refractive power different from that of the glass of which the chimney, globe or
shade is principally composed. By the introduction of the said sand or grains of
glass the light in passing from the arc, filament or flame through the chimney,
globe or shade made of glass of the kind described does not pursue the rectilinear
path which it would were the glass homogeneous but is so irregularly refracted and
diffused that the intensely bright image of the arc, filament or flame is to a great
extent lost the whole of the chimney, globe or shade becoming luminous. In this
way a soft or subdued light radiated from a large surface is obtained without any
less of the original light beyond that which occurs when a perfectly transparent
glass is employed.
"
"
""
The incorporation of the sand or particles of glass having a different refractive
power from that of the glass into which it is introduced and which I will call the
body glass may be effected in various ways. The following way I have found to
answer well in practice. The workman gathers on the "iron or blowing pipe a
quantity of the body glass from the pot and "marvers it into the desired shape.
He then rolls or "marvers" it on a દ marver on which the sand or particles of
glass have been evenly spread or dusted. The said sand or particles of glass are
taken up by the body glass and form an external layer thereon. The workman
then gathers on the body glass thus treated an additional quantity of the body glass
and proceeds to "marver the mass and fashion it into a chimney, globe or shade
in the ordinary way. The particles of sand or glass are thus enclosed between and
incorporated with an inner and outer layer of body glass. The said sand or
particles of glass being in optical contact with the body glass there is no loss
in the light passing through the chimney, globe or shade, the effect of the
sand or particles of glass being to produce the irregular refraction hereinbefore
referred to.
Chimneys, globes and shades for lamps made according to my invention being
quite smooth internally and externally do not favour the adhesion of dirt as
roughened glass does and are as easily cleaned by washing as ordinary glass
chimneys, globes or shades are.
Dated the 23rd day of February 1892.
W. T. WHITEMAN,
Agent for the Applicant.

page_text: COMPLETE STEUITUATION.
Improvements in the Glass Chimneys, Globes, and Shades of Electric
and other Lamps.
I ALBERT CAY, trading as James Stevens and Son and also as Stone, Fawdry
and Stone of Dartmouth Street, Birmingham in the County of Warwick, Glass
Manufacturer, do hereby declare the nature of my invention and in what manner
the same is to be performed to be particularly described and ascertained in and
by the following statement :-
In electric and other lamps where the incandescent arc or filament or flame has
so intense a luminosity as to be distressing to the eye, the light is sometimes
diffused by the use of a chimney, globe or shade made of opalescent or semi-
transparent glass or of transparent glass roughened on one of its surfaces.
In these methods of diffusing the light there is a considerable loss of light. This
is undesirable and the object of my invention is so to diffuse the light as to prevent
pain to the eye, and at the same time to reduce loss of light.
My said invention consists in introducing into the glass of which the chimney,
globe or shade is made grains of sand or particles of glass having a refractive power
different from that of the glass of which the chimney, globe or shade is principally
composed. By the introduction of the said sand or grains of glass the light in
passing from the arc, filament or flame through the chimney, globe or shade made
of glass of the kind described, does not pursue the rectilinear path which it would
were the glass homogeneous but is so irregularly refracted and diffused that the
intensely bright image of the arc, filament, or flame is to a great extent lost.
The incorporation of the sand or particles of glass having a different refractive
power from that of the glass into which it is introduced and which I will call the
body glass may be effected in various ways.
"
The following way I have found to answer well in practice. The workman
gathers on the "iron" or blowing pipe a quantity of the body glass from the pot
and "marvers it into the desired shape. He then rolls or "marvers" it on a
"marver" on which the sand or particles of glass, preferably heated, have been
evenly spread or dusted; or he rolls it in a crucible containing the sand or particles
of glass. The said heated sand or particles of glass are taken up by the body glass
and form an external layer thereon. The workman then covers the body glass thus
treated with an additional quantity of the body glass either by gathering it from
the pot or by casing it with a cup separately made, and proceeds to "marver
mass and fashion it into a chimney, globe or shade in the ordinary way. The
particles of sand or glass are thus enclosed between and incorporated with an inner
and outer layer of body glass. The said sand or particles of glass being in optical
contact with the body glass there is little loss in the light passing through the
chimney, globe or shade, the effect of the sand or particles of glass being to produce
the irregular refraction hereinbefore referred to.
"the
Chimneys, globes and shades for lamps made according to my invention being
quite smooth internally and externally do not favour the adhesion of dirt as
roughened glass does and are as easily cleaned by washing as ordinary glass
chimneys, globes or shades are.
The sand I prefer to employ is the almost colourless sand used in the manufacture
of table glass. Where however it is desired to give a slight colour to the lamp
chimney, globe or shade this may be effected by the employment of particles of
coloured glass or sand.
Thus ordinary red sand will give a faint orange colour to the light transmitted
through the lamp chimney, globe or shade. Similarly particles of glass faintly
coloured blue by oxide of cobalt will give a delicate blue colour to the glass of the
chimney, globe or shade; this is so nearly complimentary to the colour of the light
produced by the burning of coal gas and ordinary illuminants (hydro-carbons) that

page_text: the light of burning hydro-carbons may thereby be rendered nearly white. Similarly
by particles of other coloured glasses, other tints may be given to the lamp chimney,
globe or shade.
Although in practice I have found that sand and particles of glass answer well
yet I do not limit myself to the use of these substances, as other siliceous substances
may be used in place of sand; such for example, as powdered flint and powdered
rock crystal.
Having now particularly described and ascertained the nature of my inven-
tion and in what manner the same is to be performed I declare that I claim as
my invention of "Improvements in the glass chimneys globes or shades of electric
and other lamps "-
-
Introducing into or embedding in the glass of which the said chimneys, globes and
shades are made, grains of colourless or coloured sand or other siliceous material or
particles of glass, colourless or coloured, the said siliceous material or glass having
a refractive power different from that of which the said chimneys, globes and shades
are made for the purpose and substantially as herein before described.
Dated the Seventeenth day of November 1892.
ALBERT CAY.