IMPROVED MEANS OF SOFTENING OR DIFFUSING THE ELECTRIC AND OTHER LIGHT
Year: 1878

page_text: LETTERS PATENT to Alexander Melville Clark, of Chancery Lane, in the
County of Middlesex, Patent Agent, for the Invention of "IMPROVED MEANS
OF SOFTENING OR DIFFUSING THE ELECTRIC AND OTHER LIGHT."
nication from abroad by Louis Clémandot, of Paris, France.
A commu-
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark at
the Office of the Commissioners of Patents on the 11th October 1878.
ALEXANDER MELVILLE CLARK, of Chancery Lane, in the County of Middlesex,
Patent Agent. "LMPROVED MEANS OF SOFTENING OR DIFFUSING THE ELECTRIC
AND OTHER LIGHT." [A communication from abroad by Louis Clémandot, of
Paris, France.]
This Invention relates to an improved means of diffusing and softening the
electric light, or light obtained from gas, oil, magnesium, or other source, and consists
in the employment of glass globes, or lanterns, or envelopes, made double or with
two skins, and having the intervening spaces filled with a material of a flocculent
nature, capable of reflecting, screening, and diffusing the light. The partially opaque
glass hitherto used for the purpose can only soften or diminish the excessivo
brilliancy by absorbing more or less of the light, which is thus lost.
The only way of attaining the desired result is to diffuse the light in much the
same way as the light of the sun is diffused by clouds floating in the atmosphere,
and this is effected according to this Invention by enclosing the light within a
medium of a flocculent nature, which is capable of being illuminated by and of
screening and diffusing the light.
The substances to be employed for the purpose should be inalterable, and moro
or less opaque and dense. I propose to employ powdered glass, glass wool, or
D

page_text: wadding, spun glass, calcined mica, silver leaf, or other material, employed either
singly or in combination. The materials may be of various degrees of fineness,
and may also be tinted, or the glass globes or envelopes may be tinted.
The intensity of the light radiated from the glass globe or envelope depends on
the thickness of the layer contained in the space between its walls, and by varying
this according to the intensity of the light itself a maximum of useful effect is
obtained.
The annexed Drawing shows various forms of double globes, lanterns, or glass
envelopes for the above-mentioned purpose. In one case a globe is shown made in
two parts.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alexander Melville Clark in the Great Seal Patent Office on the 10th
April 1879.
ALEXANDER MELVILLE CLARK, of Chancery Lane, in the County of Middlesex,
Patent Agent. "IMPROVED MEANS OF SOFTENING OR DIFFUSING THE ELECTRIC
AND OTHER LIGHT." A communication from abroad by Louis Clémandot, of
Paris, France.
This Invention relates to an improved means of diffusing and softening the
electric light, or light obtained from gas, oil, magnesium, or other source, and the
Invention consists in the employment of glass globes, lanterns, or envelopes, made
double or with two skins, and having the intervening space filled with a material of
a flocculent nature, which will allow of the light percolating through it, and which
is capable of reflecting and diffusing the light in order to convert intensity into
volume of light. The partially opaque glass hitherto used for the purpose only
softens or diminishes the excessive brilliancy by absorbing the greater part of the
light, which is thus lost. The only way of attaining the desired result is to diffuse
the light in much the same way as the light of the sun is diffused by clouds floating
in the atmosphere, and this is effected according to this Invention by enclosing the
light within a medium of a flocculent nature, which is capable of being illuminated
by, and of allowing the light to percolate through it for the purpose of its
diffusion.
The substances employed for the purpose should be inalterable, and more or less
opaque and dense. I propose to employ powdered glass, glass wool (which answers
the purpose perfectly), spun glass, calcined mica, or silver leaf, employed either
singly or in combination. The materials may be of various degrees of fineness, and
may also be tinted, or the glass globes or envelopes may be tinted. The intensity
of the light radiated from the glass globe or envelope depends on the thickness of
the layer contained in the space between its walls, and by varying this according
to the intensity of the light itself, a maximum volume of light is obtained. The
glass globes, envelopes, or lanterns, need not necessarily be made of transparent
glass, but may according to circumstances be ground, "crackled," colored, or made
up of prisms or lenses (convex or concave). They may even be made of separate
rods or tubes, in order to break up, divide, and multiply the luminous rays before
they pass through the intermediate diffusing medium above described. In order
that the Invention may be more readily understood I will describe two particular
examples.
If the electric or other light be surrounded by an inner envelope or globe made
up of say 40 lenses juxtaposed and fitted together by any suitable means, each lens
will collect and condense the rays which fall on it, and from the single initial light
there will be obtained 40 luminous foci. From each of these the light will proceed
through the diffusing medium contained between the inner and outer envelopes, and
be thence multiplied and distributed all around. Thus the principal focus of light
is first divided into a number of secondary foci, the light from each of which is
diffused to the required extent. If the inner envelope be made of crackled or
frosted glass, presenting a crystalline aspect, the light will be rendered brilliant and
sparkling before being diffused, and similarly in the other cases mentioned generally
above.
The annexed Drawing shows as examples various forms of double globe, lanterns,
or envelopes, with a diffusing medium contained between the inner and outer skins.
In one case a globe is shown made in two parts.
Having described the nature of the Invention, and the manner of performing the
samo I declare that what I claim as the Invention to be protected by the herein-
before in part recited Letters Patent is,--
The improved means of diffusing artificial light, consisting in the employment of

page_text: double glass globes, envelopes, or lanterns, having the space between the inner and
outer walls filled with a material capable of allowing the light to percolate through
it, and of reflecting and diffusing the light as herein specified."
In witness whereof, I, the said Alexander Melville Clark, have hereunto set
my hand and seal, this Tenth day of April, in the year of our Lord One
thousand eight hundred and seventy-nine.