Improvements in Glass Reflector Mirrors.
Year: 1894

page_text: Date of Application, 23rd June, 1894
Complete Specification Left. 22nd Apr., 1895-Accepted, 1st June, 1895
PROVISIONAL SPECIFICATION.
Improvements in Glass Reflector Mirrors.
We The Honourable CHARLES ALGERNON PARSONS, JAMES BONELLE
WILLIS, and GEORGE GERALD STONEY, all of Heaton Works, Newcastle-on-
Tyne, Engineers, do hereby declare the nature of this invention to be as
follows:-
-
Our invention relates to glass reflector mirrors, such as are used for search light
projectors, and our object is to mount the mirrors in a more secure and protected
manner than hitherto, and further to cool the mirrors in such manner as to
prevent any inconvenient increase of temperature, even when the said reflectors are
placed near the most powerful electric arcs.
Our invention consists in mounting the mirror in a metal backing, constructed
to enclose a considerable space between the said metal backing and the back of
the mirror, and in cooling the mirror by passing water or air through the
backing.
In one method of carrying our invention into effect, we construct the glass
reflector or mirror in any usual manner, and we provide a metal disc backing, in
the form of a hollow cup, preferably corrugated in concentric rings, so as to give
considerable elasticity. We attach the glass mirror to this disc or cup backing by
means of metal rings clipped together on the glass, having packing of sufficient
softness between the metal rings and the glass.
We sometimes make the packing water-tight, and introduce water into the space
behind the mirror and the metal cup. We also connect the said water jacket
to a circulating tank by pipes, to enable the water to circulate by convection
as we run water through the jacket in sufficient quantity to keep the temperature
of the mirror within the desired limits.
Instead of water we sometimes circulate air through the jacket space, the air
circulation may be caused by the heat, and suitable holes may be provided in
the metal back, or we may force air through by a fan driven by a convenient
motor, such as an electro-motor.
The metallic plate backing is made of sufficient elasticity to allow of the
expansion of the mirror when heated, and it protects the mirror from accident
in handling, and also protects the silvering and paint from heat or mechanical
injury.
We prefer concentric ring corrugations in the backing plate, but other forms
of corrugation may be adopted.
The edges of the backing plates may be bent to form clips for holding the
mirror in place, or the mirror may be secured to the back by a separate ring
or segments, as herebefore described.
The backing plate may be externally or internally covered with gills or ribs,
to increase the radiating or conducting surface.
The space occupied by the water jacket may instead be filled with a solid or
crystals, such as acetate of soda, having considerable Intent heat of fusion,
and such a solid will keep down the temperature of the mirror for a considerable
period while in the act of fusion.
It is to be understood that a mirror, mounted in accordance with our invention,
may be placed on a search light projector, and subjected to greater intensity of

page_text: arc and radiant heat than a mirror mounted in the usual manner, so that it
may be used in conjunction with n more powerful are having a shorter focal length.
Dated the 23rd day of June 1894.
MARKS & CLERK,
18, Southampton Buildings, London, W.C., Agents.
Improvements in Glass Retector mirrors.
We, The Honourable CHARLES ALGERNON PARSONS, and JAMES BONELLE
WILLIS, and GEORGE GERALD STONEY, all of fleaton Works, Newcastle-on-
Tyne, in the County of Northumberland, Engineers, do hereby declare the nature
of this invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:-
Our invention relates to glass reflector mirrors, such as are used for search light
projectors, and our object is to mount the mirrors in a more secure and protected
manner than hitherto, and further to cool the mirrors in such a manner as to
prevent any inconvenient increase of temperature, even when the said reflectors
are placed near the most powerful electric ores.
Our invention consists in mounting the mirror in a metal backing, constructed to
enclose a considerable space between the said metal backing, and the back of the
mirror and in cooling the mirror by passing water, any other liquid or air through
the backing.
Referring to the accompanying drawings.
Figure 1 is a section through a search light projection showing the application
of our invention to the reflector mirror.
Figure 2 is a section through the mirror shown at Figure 1 but drawn at
Figure 2 to a larger scale.
Figure 3 is a section similar to Figure 2 showing the application of cooling ribs
or gills.
In one method of carrying our invention into effect we construct the glass
reflector or mirror A in any usual manner, and we provide a metal disc backing B
Figures 1, 2, 3, in the form of a hollow cup, preferably corrugated in concentric
rings, as illustrated so as to give considerable elasticity. We attach the glass
mirror A to this dise or cup backing B by means of metal rings clipped together on
the glass, having packing of sufficient sufiness between the metal rings and the glass,
or by turning over the edge of the cup barking as shown at B Figures 2 and 3
securing the glass reflector by the soft packing B³.
We sometimes make the parking water-tight, and introduce water or other
suitable liquid into the space behind the mirror and within the metal cup.
We
also connect the said water jacket to a circulating tank by pipes, to enable the
water or liquid to circulate by convection or we run the water or liquid
through the jacket in sufficient quantity to keep the temperature of the mirror
within the desired limits.
At Figure 1 we show the water jacket arrangement in conjunction with the
water tank G. The water from the tank G circulates by way of the pipes E and F
through the space between the backing B and the reflector A. The direction of
the circulation is shown by the arrows 1 and 2 Figure 1.
Instead of water we sometimes circulate nir through the jacket space, the air
circulation may be caused by the heat, and suitable holes may be provided in
the metal back or we may force air through by a fan driven by a convenient motor
such as an electric-motor.
The metallic plate backing B is made of sufficient elasticity to allow of the
expansion of the mirror when heated and it protects the mirror from accident

page_text: in handling, and also protects the silvering and paint from heat or mechanical
injury.
We prefer concentric ring corrugations in the backing plate, such as are shown
in the drawings but other forms of corrugation may be adopted.
The edges of the backing plate may be bent to form clips for holding the mirror
in place, or the mirror may be secured to the back by a separate ring or segments,
as hereinbefore described.
The backing plate may be externally or internally covered with gills or
ribs, to increase the radiating or conducting surface. Such gills are shown
at K K K K K at Figure 3, there they form ring gills projecting from
the back of each corrugation.
The space occupied by the water jacket may instead be filled with a solid or
crystals, such as acetate of soda, having considerable latent heat of fusion, and
such a solid will keep down the temperature of the mirror for a considerable period
while in the act of fusion.
Figure 1 shows a search light projection H with a cooling tank G mounted over
it; the mirror with its cup backing is held in the metal ring 1 by the clastic clip
arrangement D. C is an additional back plate which is fitted to the ring 1 and
protects the corrugated cup backing.
It is to be understood that a mirror, mounted in accordance with our invention,
may be placed on a search light projector, and subjected to a greater intensity
of arc and radiant heat than a mirror mounted in the usual manner, so that it
may be used in conjunction with a more powerful arc having a shorter focal
length.
It is also to be understood that any liquid which does not act on the mirror
backing or metal and is otherwise suitable, may be used for cooling.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what
we claim is―
1. In glass reflector mirrors; mounting the mirrors in a metal backing so
arranged as to grip and hold the said mirror in an elastic manner in order to
afford greater protection from breakage substantially as herein before described.
2. In glass reflector mirrors; mounting the mirror in a metal backing and
passing water or other cooling liquid through the space between the two for the
purpose of cooling the mirror so preventing over-heating by the arc or other lamp,
substantially as hereinbefore described.
3. In glass reflector mirrors; mounting the mirror in a metal backing and passing
air between the mirror and the backing by a fan or other device substantially as
hereinbefore described.
4. In glass reflector mirrors; cooling the mirror by means of a solid substance
having considerable latent heat of fusion such as acetate of soda, as described.
5. In glass reflector mirrors; mounting the mirror in a corrugated metal
backing, as and for the purposes hereinbefore described and illustrated at
Figures 1, 2 and 3.
1
ስለ ኪ.
A 1905
MARKS & CLERK,
18, Southampton Buildings, London, W.C., and
13, Temple Street, Birmingham, Agents for the Applicants.