IMPROVEMENTS IN REFLECTORS FOR ILLUMINATING PURPOSES
Year: 1884

page_text: I GEORGE MILLS of 18 Renfrew Road, Kennington in the County of Surrey,
Engineer do hereby declare the nature of my invention for "IMPROVEMENTS IN
REFLECTORS FOR ILLUMINATING PURPOSES," to be as follows:-
The object of this invention is to provide a simple and durable reflector which
shall cause a wide-spread diffusion of white light from a gas jet, or equivalent
sourco of light.
To this end the invention consists in a novel combination of reflecting surfaces
the one serving to concentrate the light and the other to throw off the concentrated
rays at obtuse angles.
In carrying my invention into effect I employ a silvered or polished reflector,
and in combination with and surrounding this silvered reflector I use a white
enamelled or semi-transparent annular reflector preferably made of "albatrine" or
porcelain the two being united by a setting of plaster of Paris or equivalent non-
conducting cement. The annular or funnel-shaped reflector is forined with a
flange or recess at its smaller end and the smooth metallic or silvered reflector
fitting within this flange can be readily secured in place by a filling of plaster or
cement. The angle which the sloping face of the annular white enamel or
albatrine reflector makes with a line perpendicular to the silvered central reflector
may be varied according to the concavity or other form of the latter and the degree
of diffusion required, but it will usually be one of about 45°.
.
As the annular porcelain or albatrine, reflector is nearest the flame, and is capable
of withstanding great heat, and the silvered reflector is at a distance from the
flame and is further insulated by the plaster of Paris setting from the heat
transmitted through the albatrine, such compound reflectors are more durable than
others in common use and can be produced more economically. Moreover they
give a soft steady widely diffused light of greater whiteness than can be obtained
from silvered reflectors alone, and are likely on that account to be of great use to
jewellers and others requiring a steady white light for the display of their goods
'while the formation of strong black shadows behind the reflector is avoided. Such
compound reflectors are particularly suitable for lighting corridors, passages and
stables, as a single jet can be caused to throw a light into every corner,

page_text: Fig: 2 a transverse section thereof.
A represents a silvered or polished concave reflector, and B indicates a white
semi-transparent or annular reflector preferably made of "albatrine" or porcelain
which surrounds, or frames, so to speak, the concave mirror or reflector A.
This concentric annular reflector B is of shallow funnel shape as seen in Fig: 2
its inner surface being preferably quite flat or level when seen in cross section ;
that is the reflector B is preferably curved only in a circumferential and not in a
radial sense.
The reflector B is formed with a flange or recess b at its rear or smaller end, and
the smooth metallic or silvered reflector A is of a size to fit within this flange or
recess and is secured therein by a filling of plaster or cement, a, of any suitable
kind.
The concentric annular reflector B might be made of white enamelled metal or
other suitable white reflecting substance. The angle which the sloping face of the
annular white enamel or albatrine reflector B makes with a line perpendicular to
the silvered central reflector A will vary somewhat according to the concavity of
the latter and the degree of diffusion required, but will usually be one of about 50°,
as represented in full lines in the Drawing, but an angle of 60° as shown in the
dotted lines is found to give good results and ensures a wider range of diffusion
with an annular reflector of less depth, but similar diameter. The position of the
gus jet or other source of light with reference to the compound reflector is indicated
at C Fig: 2.
As the annular porcelain or albatrine reflector is nearest the flame, and is capable
of withstanding great heat, and the silvered or polished metal reflector is at a
distance from the flame, and is further insulated by the plaster or cement filling a
from the heat transmitted through the albatrine, such compound reflectors are

page_text: more durable than others in common use and can be produced more economically.
Moreover they give a soft steady widely-diffused light of greater whiteness than
can be obtained from silvered reflectors alone, while the formation of strong black
shadows behind the reflector is avoided. The reflectors when in use present the
appearance of a very brilliant central spot of light surrounded with a luminous
ring of flame, and are particularly suitable for lighting corridors, passages, stables,
railway platforms and fire-engine stations, as a few jets can be caused to throw a
light into every corner.
These reflectors may be embedded in the wall with advantage and protected
against accidental damage by shallow lanterns.
The reflector and lantern may both be embedded so as to lie flush with the wall.
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
1. A compound reflector consisting of a concave polished or silvered contral
portion A, and an inclined reflecting surface or surfaces of albatrine, porcelain or
white enamel surrounding the said central portion, substantially as and for the
purpose described with reference to the accompanying drawing.
2. In a reflector, the combination with a concave mirror or polished metal
reflector such as A, of an annular funnel-shaped semi-transparent reflector B, of
porcelain or equivalent material, provided with a flange or recess as at b, substantially
as and for the purpose set forth.