An Improved Manufacture of Reflectors.
Year: 1895

page_text: Date of Application, 16th Mar., 1895
Complete Specification Left. 16th Jan. 1896-Accepted. 14th Mar.. 1896
PROVISIONAL SPECIFICATION.
An Improved Manufacture of Reflectors.
We, SHERARD OSBORN COWPER-COLES, of 16 Adam Street, Manchester
Square, in the County of Middlesex, Engineer, and LEONARD WILLIAM NORTH
HICKLEY of 10 King's Bench Walk, Temple, in the County of London, Solicitor,
do hereby declare the nature of this invention to be as follows:-
This invention relates to an improved manufacture of reflectors, and has for its
chief object to provide improved parabolic and other reflectors suitable for electric
search-lights, for example, made by an improved method, and at a much less cost
than heretofore.
Our improved reflectors are formed by electro-deposition and are characterized
by a reflecting surface formed of palladium, or palladium alloyed with silver, or
chromium and a backing of copper or other metal or alloy which can be
easily and cheaply deposited; the copper may be backed with other suitable
substance such as papier mâché.
One of the chief features of our improved method of producing parabolic and
other reflectors consists in depositing the metals which are to constitute the
reflector upon a carefully prepared wax mould or upon a ground and polished glass
surface of the shape which it is desired the reflectors shall have. The said
deposited metals take accurately the shape of the prepared glass or wax mould and
when removed therefrom the surface thereof will not require to be ground or
polished; hence by this process, we are enabled to produce in a very cheap manner
from a carefully prepared standard surface any number of correctly formed
reflectors.
In carrying our invention into practice we first cover the surface of the prepared
We then
glass with a very thin coating of silver by any known method.
preferably pass a tool similar to a burnishing tool over the silver coating which has
the effect of loosening without actually detaching it from the glass. We next
electrically deposit a layer of palladium or of an alloy containing palladium on the
silver, and finally we deposit a backing of copper zinc or other suitable metal on
the palladium.
The compound metals so formed are then removed from the glass and constitute
the reflector. The silver face is either removed entirely or is caused to sink into
the palladium by applying heat thereto, we prefer to adopt the latter plan. In
this manner a palladium silver alloy is formed which is very advantageous as a
reflecting surface, as the palladium or the alloy thereof does not tarnish and the
silver has the effect of producing great brightness.
The copper may be consolidated by a burnishing tool while being deposited. In
some instances we make the copper back with a corrugated surface.
According to a modification of the above method we deposit a thin layer of
silver on a glass mould and then deposit electrically copper or other metals on the
back of the silver to form the body of the reflector. We then remove the deposited
metals and coat the silver face thereof with palladium or other non-tarnishable
metal or metals.
In other instances we do not use a glass surface on which to deposit the metals,
but proceed as follows, that is to say, we deposit the metals forming the reflector
from suitable baths upon a mandrel or mould of the proper size and shape and

page_text: made of suitable materials as hereinafter explained.
The construction of the
mould on which reflectors are made forms an important feature of this part of our
invention. The said mandrel or mould may be rotated slowly during the operation,
or the burnishers hereinafter described may be rotated around the mould in which
case the latter may be stationary. We prefer to consolidate and burnish the deposit
as it accumulates, by means of suitable automatic burnishers which press upon and
are slowly moved over, the surface of the deposit.
The palladium or an alloy containing that metal may first be deposited upon the
mould from a suitable bath containing such metal or alloy in a heated condition,
and when a suitable thickness has been obtained, the partially-formed reflector with
its mould is transferred to another bath, and a further layer of copper or other
suitable metal is deposited upon the palladium, to form a backing therefor. As
soon as the desired thickness has been attained, the reflector is removed from the
bath and the mould is then disengaged and extracted, whereupon the reflector,
either with or without further finishing on its inner face is ready for use. The
finishing herein referred to, is not a polishing operation such as would interfere
with the trueness of the reflecting surface, but is merely what is known to electro
platers as a hand colouring operation.
According to this part of our invention we produce reflectors by the aid of
moulds made of iron and coated with copper which may be further coated with one
of the rarer metals such as silver and palladium, or alloys of such metals. The
surfaces of the moulds are highly polished by any suitable methods so that the
reflectors formed thereon are quite true on their inner surfaces and when removed
therefrom are ready for use either with or without the finishing above referred to..
As an alternative we may coat a mould of suitable material with wax, the mould
being finally mounted upon a rotatable spindle and given the desired curvature
with properly shaped tools and templates. The surface of the mould is made
an electric conductor by projecting on it bronze or plumbago powder upon which
the metallic reflector is deposited. It will be seen that the reflectors which we
produce do not require to undergo the very expensive polishing operation incident
to the manufacture of reflectors made by methods heretofore known and used.
We
are therefore able to produce very cheap and accurate reflectors. Moreover
reflectors made in accordance with our invention will maintain their true form and
may be subjected to rough usage without fear of damaging them.
According to further modification we provide a mould made of sulphur mixed
with plumbago which may be cast into a glass mould. The reflector is then built
up on the said sulphur and plumbago mould by the methods above described.
The palladium reflecting surface is untarnishable by the are light under ordinary
conditions, and other advantages incident to the use of this metal are that it
presents a hard surface, and adheres tenaciously to copper and cannot therefore be
readily separated therefrom.
In some cases our improved reflectors are made hollow to contain water or other
liquid and are provided with means to ensure the circulation of the said water or
other liquid when the reflector is in use thereby preventing undue heating at any
part of the reflector and consequent distortion. For the same reason the reflectors
are sometimes made of various thickness at the different parts thereof.
We will now proceed to describe, by way of example, various appliances
whereby our said invention may be carried into effect, with the aid of iron and
copper moulds.
In one arrangement according to our invention, we provide each vat or bath
with a spindle, or, where more than one reflector is to be made at the same time,
with two or more spindles, each of which projects through a suitable stuffing-box
on the bottom or side of the vat and is provided with driving gear whereby
it can be rotated. Each spindle supports, within the vat, a mandrel or mould of
cast-iron.
Adjacent to each mould an anode is supported, of the metal or alloy which is
required to be deposited; the mould forms the cathode, and each anode and

page_text: cathode is placed in electrical connection, by suitable means, with the source of
current. The moulds are provided with sockets which fit coned or pyramidal
extensions upon the spindles, so as to be readily removable therefrom. The auode
may consist, for example, of a dome made of some metal or material that will not
be acted on by the electrolyte. Or suitable wooden structures may be placed
above the mould and hinged to the sides of the bath to support triangular or other
A facing
pieces of the metal to be deposited, in suitable proximity to the mould.
of unbleached calico or other suitable material is placed below the said strips to
catch any impurities which may fall therefrom and to prevent them from falling
upon the reflector. We provide, as aforesaid means for burnishing and compacting
the metal deposited upon the mould. For example, we provide a shaft to turn in
suitable bearings above the vat and we connect the said shaft, by screw-threads
formed thereon, to small carriages arranged to reciprocate upon rails which extend
across the vat. To each carriage we hinge an arm to which at its free end, a
roller is pivoted. By the reciprocation of the carriage the roller is drawn over the
surface of the metal on the mould while the said mould is rotating and thus the
metal as it is deposited, is compacted by the burnishing action of the roller. One
of the said carriages is connected or adapted with a sliding rod, with belt-shifting
device and tappets or their equivalent thereon, so that at the extreme of recipro-
cation of the carriage the reversal of the motion of the screw-threaded shaft, and
consequently, of the carriages, is effected; the carriage for instance, moves the
sliding rod, and the guide on the said rod shifts an open belt on to a loose pulley
and puts a crossed belt on to a fast pulley, or vice versa. A weight is arranged to
slide upon the aforesaid arm, so that the pressure upon the burnishing roller may
be varied by altering the position of the weight relatively to the roller, while the
roller moves from a larger to a smaller diameter of the reflector, for example.
Unless such a variation of pressure were arranged for, some parts of the reflector
would be burnished too much, whilst other parts would not be burnished
sufficiently.
The movement of the said weight is preferably effected automatically, for
example, by means of gearing carried by each carriage and operated by the screw
A drum is
by which, as aforesaid, the movement of the carriage is effected.
connected to the said gearing and a cord or the like connected to the weight is led
to the drum over suitable guiding pulleys on the arm and carriage; by the
rotation of the drum the cord or the like raises or lowers the weight upon the arm.
The moulds may be arranged in the vat in two parallel rows in which case a
central carriage-operating shaft will serve to operate carriages which work a pair
of burnishing devices, one such device for one mould in each row.
Before the commencement of the deposition, up on the mould or material to form
the reflector, the said mould is coated, in the usual and well known manner, so as to
enable the reflector formed by the deposition aforesaid to be readily removed from
the mould when finished.
The flange of the mould is provided with suitable studs recesses or hollows so as
to allow of the insertion of a tool therein to facilitate the removal of the reflector
from the mould.
As an alternative construction we may arrange two shafts upon which the moulds
are carried, and the gearing by which the moulds are rotated, inside the vat,
entirely or partially. For example, we may attach footstep bearings for the mould
shafts to the bottom of the vat, inside, forming them in tubular castings which
protrude to the outside through fluid-tight openings.
The driving shaft or shafts may pass from the outside to the inside of the vat
through one or more studding-boxes in the bottom or in the wall thereof and may
have worm or other gearing thereon, within the vat, to gear with suitable gear
wheels placed upon the mould spindles, just below the moulds and ordinarily
immersed in the solution. For instance a single spur pinion on the driving shaft
may rotate a spur wheel on each of two core mould spindles.
This invention comprises also alternative arrangements of the burnishing devices.
•

page_text: In one such arrangement a guide is hinged within the vat and endless cords, chains
or the like are operated by gearing arranged so as to move small carriages,
containing rollers, along the said guides, which are adapted to conform with the
outline of the article formed on the core, and cause the rollers to traverse the
article in such a manner that all the metal or alloy deposited comes from time to
time, under the influence of the rollers. Springs can be provided to force the guide
always towards the article operated upon.
In another construction the rollers are carried at the ends of weighted levers
hinged to a collar which is raised and lowered in the line of the axis of the reflector
by a screwed spindle lying in the same line.
In all cases the guides or supports for the burnishing rollers are arranged so as
to be movable, or otherwise so that they offer no obstruction to the removal of the
finished article. The burnishers may also be worked by means of a cam or
eccentric, which impart a travel thereto which need only equal one fourth the
diameter of the reflector if two burnishing arms are employed and arranged at a
suitable distance apart.
In other constructions of our improved apparatus the mould-spindle is placed in
an inclined position within the vat.
The mould spindles, whether vertical or inclined, can be made telescopic and
fitted with suitable screw or other gear whereby they can be extended for the
purpose of raising the mould out of the bath when required.
In one example of vat with inclined mould-spindle, the mould is carried upon a
spindle which is movable endwise in a rotatable sleeve, the spindle being screw-
threaded, and the sleeve having a hand-wheel or nut which gears with the threads
of the spindle to move the same.
The deposited metal may be inspected during the process of deposition by
drawing off and returning the solution to the depositing vat by lowering and
raising a cistern or barrel connected to the bottom of the tank by a flexible hose.
The vats, in cases where the mould-shafts are inclined, are sometimes made
V-shaped in cross-section, with the walls at right-angles to the mould spindles.
A convenient apparatus for use in the coating of the mould with palladium or
chromium is arranged as follows:-
A steam jacketed pan, lined with lead or other suitable anode to contain the
palladium solution, is supported upon a ram which can be raised and lowered
hydraulically or by screw-gearing or otherwise, to bring the solution which it
contains, into contact with the mould, which is independently supported.
The ram may be screw-threaded, and can, in such a case, be raised and lowered
by a nut carried on a pedestal adapted to encircle the ram.
Posts or standards are placed around the pan and the mould is supported, while
immersed in the palladium solution, by means of links or hinge-attachments carried
by the posts and engaging with eye bolts provided on the mould. Two spare
standards are provided in such a position that by simply turning the mould about
the other standard as about a hinge it will be inverted and received upon the said
spare standards in a convenient position for inspection or treatment.
"
It is obvious that by the process hereinbefore set forth the different parts of the
reflector can be made of various thicknesses by the process of "stopping off'
other suitable means.
or by
Furthermore the palladium or an alloy of the same may be
applied to the reflector in the form of an amalgam, in the same way that mercurial
gilding is done.
Dated this 10th da M
1005
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicants.

page_text: An Improved Manufacture of Reflectors.
We, SHERARD OSBORN COWPER-COLES, of 16 Adam Street, Manchester
Square, in the County of Middlesex, Engineer and LEONARD WILLIAM NORTH
HICKLEY, of 10 King's Bench Walk, Temple, in the County of London, Solicitor,
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:―
This invention relates to the manufacture of parabolic and other reflectors
which are more especially suitable for electric search-lights, the chief object of
the invention being to produce reflectors of increased durability and at much
less cost than heretofore.
Our improved reflectors have preferably a reflecting surface of palladium or
palladium-silver alloy and a backing of copper or other suitable metal applied by
electro-deposition. The copper or other backing may be corrugated, or its
thickness and rigidity may be increased by affixing thereto papier mache or other
suitable material.
For the purpose of our invention we employ a mandrel or mould of wax, glass,.
metal, or other suitable material, the surface of such mould being highly polished and
truly formed to the parabolic or other shape that is to be imparted to the reflector.
This truly formed parabolic or other surface of the mould is covered with a thin
coating of silver by a method of chemical deposition such as that generally adopted
in the production of silvered mirrors.
Previous however to the deposition of the silver, the mould is treated with
beeswax dissolved in benzine or other volatile solvent whereby a thin film of solid
wax is left upon the surface of the mould when the solvent evaporates. When this
wax film has sufficiently solidified we rub the same with a piece of chamois
Jeather or other suitable material so as to impart to the wax a fine polished
surface.
If moulds of glass be employed this treatment will be found especially useful,.
as it prevents the almost imperceptible scratches on the surface of the mould from
becoming deeper and more pronounced by wear which would otherwise occur
after using the moulds for some time and would eventually render them useless.
After the silver has been deposited on the mould it is then subjected to a
burnishing or rubbing operation with a piece of chamois leather or other suitable
material which will loosen but not actually detach, the chemically deposited silver
from the mould. This burnishing or rubbing operation also has the effect of giving
a polished surface to the back of the silver coating which enables the copper or
other backing which is subsequently deposited onto the silver coating, to effectually
adhere to the silver. Therefore when the completed reflector is removed from the
mould, the reflecting surface of silver will leave the mould without any particles.
of its surface remaining behind and adhering to the mould.
In order to prevent
the copper or other metal backing from creeping between the silver coating and
the mould during the deposition thereof, we "stop off" the edge of the silver
coating, that is to say we coat the edge thereof with any suitable paint or compound
that will not be affected by the electrolyte. The mould with its chemically
deposited and polished silver surface is then placed in a suitable electrolytic tank
wherein it receives a coating of palladium by electro-deposition. The mould with
its compound surface of silver and palladium is then removed from this electrolytic
tank and placed in another wherein it receives the backing of copper or other
suitable metal by electro-deposition, the said mould being revolved during this
operation. On the insertion of the mould into the copper depositing tank we prefer
to use a large current of electricity so as to ensure that the coating on the mould
shall be instantaneously covered with a layer of the copper. After this large.

page_text: When
current has been passing for about twenty minutes, it is reduced to a suitable
working current. In some cases it will be found desirable to subject the surface
of the mould to a burnishing treatment simultaneously with its revolution.
a sufficient thickness of copper has been deposited, the mould with its compound
surface of silver, palladium and copper is removed from the tank and heated to a tem-
perature of about 150° to 200° F. whereby the reflector, by its expansion, is rendered
capable of being detached from the mould. The reflector having been removed
from the mould is then either subjected to heat sufficient to cause the palladium
to be absorbed by the silver, or is treated with a solution of cyanide of potassium
or other suitable solvent whereby the silver is dissolved without detrimentally
affecting the palladium. In the former case, that is to say by the heating, we
produce a reflector having a reflecting surface of palladium-silver alloy which is
highly suitable for our purpose, as the palladium does not easily tarnish and the
silver produces a surface of great brightness. In the latter case, that is to say
when the solvent is employed, we produce a reflector having a true reflecting
surface of palladium which will be of great brightness owing to the smooth surface
of the silver upon which it was electro-deposited.
Instead of depositing the palladium upon the silver, and the copper upon the
palladium as above stated, we sometimes deposit the copper directly upon the silver
coating and the palladium or other non-tarnishable metal upon the face of the
silver coating after the latter has been detached from the mould.
In some cases that is to say when the moulds are made of metal such as iron
coated with copper and faced with silver we may deposit the palladium directly
upon the mould without first coating the latter with silver. In other cases we
may deposit the copper directly upon the silver coated mould.
In other cases we use chromium instead of palladium or silver for producing the
reflecting surface..
An important feature in our invention is that our reflectors do not require to
undergo the very extensive polishing operation incident to the manufacture of
reflectors made by methods heretofore employed, but merely require to be subjected
to what is known to electro-platers as a hand colouring operation. We are thus
able to produce our reflectors much more accurately and at less cost than has
hitherto been possible. Moreover the reflectors made in accordance with our
invention are unlikely to become deformed by inequalities of temperature which
they sometimes experience when in use, and they will also bear comparatively rough
usage without sustaining damage.
It may sometimes be found advantageous to form the reflector hollow so that
water or other liquid can be caused to circulate through it when in use and thereby
prevent undue heating of any part of the reflector and consequent distortion.
For
a similar purpose the thickness of the reflector at certain parts may be greater than
at other parts.
The aforesaid moulds may be made of a mixture of sulphur and plumbago, the
latter being somewhat in excess of the former, and be cast to the required shape
in glass moulds.
In order that our said invention may be clearly understood and readily carried
into effect we will proceed to describe the accompanying drawings in which
Figure 1 is a longitudinal section of an electrolytic tank or vat wherein the
electro-deposition of the copper or other metal is effected.
Figures 2, 3 and 4 are detail views shewing on an enlarged scale the
burnishing device employed with this tank for consolidating the metal as it is
electro-deposited onto the mandrels or moulds.
Figure 5 is a sectional elevation and Figure 6 a plan view of a tank or vat provided
with a modified arrangement of the burnishing device.
Figure 7 is a sectional elevation of a tank or vat provided with a further modified
arrangement of the burnishing device.
Figure 8 is a vertical section shewing a bath which is specially constructed for
use in the deposition of the palladium or chromium on to the moulds.

page_text: Referring first more particularly to Figures 1 to 4 A is the tank or vat which
is advantageously constructed of timber and lined with lead. B, B are the
mandrels or moulds which are detachably mounted on the upper ends of vertical
spindles bb extending through the bottom of the vat. These spindles are
provided with collars which rest upon the upper edge of foot-tep bearings C
bolted to the bottom of the vat. The lower ends of the spindles extend through
the foot-step bearings and pass through stuffing boxes D to the outside of
the vat where they are furnished with suitable gearing for enabling them to be
revolved. These spindles have square tapered upper ends to receive the moulds
which are formed with correspondingly shaped sockets or cavities.
The vat may be furnished with any convenient number of these spindles so that
several of the moulds may be acted upon at the same time.
E are the anodes which in Figure 1 are of dome shape and are supported a
short distance above the moulds in any convenient manner.
The mould constitutes
the cathode; the anodes and cathodes are connected by conductors with the
source of electric supply. E' is unbleached calico or other suitable material which
is interposed between the anode and the surface of the mould to prevent any
particles falling from the anode onto the mould. The anodes E may be furnished
with eye bolts e to permit of their being conveniently removed from the vat.
F is a shaft capable of revolving in bearings ff and extending from side to side
of the vat. This shaft is screw threaded at F1 F1 to receive correspondingly
threaded nuts or carriages G G which when the shaft revolves, travel along the
aforesaid screw threaded portions. To each carriage a bar G₁ is pivoted or
hinged at G2, and to the extremity of these bars are pivoted or hinged arms G³
having at their free ends burnishing rollers G which bear upon the curved surface
of the moulds. Projecting from each of the carriages G is a vertical extension G
which is adapted to engage with a guide rod G situated above the before
mentioned shaft F and extending across the tank. This rod G° carries a stirrup
piece G which is connected by a bar Go to a belt-fork G. f f f³ are three
belt pullies mounted on one end of the shaft F, the intermediate pulley f being
loose while the others are fast. We employ in conjunction with these belt
pullies an open and a crossed belt so that when such belts are shifted by
the fork G from the pullies f¹ to the pullies 23 and vice versa, the
direction of revolution of the shaft F is reversed. The carriages G are
thus caused to travel along the shaft F first in one direction and then in the
opposite direction, thereby causing the arms G³ to turn about their pivots and the
burnishing rollers G4 to pass alternately up and down over the curved surface of
the moulds. During this travel of the carriages and their rollers G the moulds
are constantly revolving and in this manner the whole of the curved exterior
surface of the moulds is acted upon by the burnishing rollers and the metal that
is being electro-deposited thereon is thus compacted by the burnishing action of
the said rollers. One of the extensions G on the carriages projects into the stirrup
piece G7 so that as the carriages approach the completion of their travel'in either
direction the said stirrup piece is acted upon by the aforesaid extension and shifted
along the guide rod G thereby shifting the belt fork G. The position of the
belt is thus altered and the revolution of the shaft F and the direction of travel
of the carriages 'consequently reversed. The anodes E are formed with
apertures E2 to permit of the free lateral movement of the bars G to which the
arms G³ are connected.
A weight H is arranged to slide upon each of the said arms G³ so that the
pressure of the burnishing roller G on the mould can be varied, by altering the
position of the weight relatively to the burnishing roller, as the roller moves from
a larger to a smaller diameter of the mould. Unless such a variation of pressure
. were arranged for, some parts of the reflector would be burnished too much and
other parts not enough.
The movement of this weight is preferably effected automatically and for this
purpose we may employ the means shewn more clearly in Figures 2 to 4.
Each

page_text: arm G³ is formed with a slot g through which a pin, connecting the weight to the
arm, is passed. The portion of this pin which passes through the said slot may
if desired be provided with an anti-friction roller. The weight is connected by
a cord or chain gl passing over guide pullies g², to a spool or drun g³ mounted on
a spindle carried by the carriage. This spool or drum is revolved as the carriage
travels along the shaft F, by means of a worm wheel gearing with the screw
threaded portion F' of the said shaft F. Therefore as the carriages travel along
the said shaft in one direction the spools or drums wind up the cords g' and
gradually draw the weights H up the arms G³, and, as the said carriages travel in
the opp site direction, the weights are allowed to slide down the arms G3 by the
unwinding of the cords g' from their spools as the latter revolve in the reverse
direction.
In Figures 5 and 6 we have shown modified means of effecting the burnishing
operation. In this arrangement we employ a vertical screw shaft I carrying a
nut to which are pivotally connected a pair of arms 12 13 having adjustable
weights 12x [3x. When the shaft I revolves in one direction the nut 11 ascends
and the weights gradually cause the burnishing rollers G to advance towards each
other as they ascend on the surface of the mould. The shaft may be carried
at the free end of an arm I which is pivoted at 15 to the edge of the vat A so as
to permit of the parts being readily turned to one side when the mould is to be
removed from the vat.
In Figure 7 we have shewn another burnishing device in which we employ a
curved arm J hinged at J¹ to the inside of the vat and connected at its upper end
by an adjustable stay rod J' to the side wall of the vat. This arm is provided with
sprocket wheels J3 J4 near its upper and lower ends and passing around these
sprocket wheels is an endless chain or belt J furnished with burnishing rollers J.
When the endless band J is put into motion by the revolution of the wheels J3 J4 the
rollers J are caused to travel successively over the curved surface of the mould.
We do not confine ourselves to these methods of effecting the burnishing operation
as any other convenient arrangement may be employed for the purpose.
In all cases the guides or supports for the burnishing rollers are arranged so as
to be movable so that they offer no obstruction to the removal of the finished
article. The burnishers may also be worked by means of a cam or eccentric, which
imparts a travel thereto, the extent of travel being only equal to one fourth the
diameter of the reflector if two burnishing arms are employed and arranged at a
suitable distance apart.
The flange B of the moulds may be provided with suitable studs recesses or
hollows so as to allow of the insertion of a suitable toot thereinto to facilitate
the removal of the reflectors from the moulds.
In other constructions of our improved apparatus the spindles b are placed in an
inclined position within the vat.
These spindles whether vertical or inclined, can be made telescopic and can
be fitted with suitable screw or other. gear whereby they can be extended for the
purpose of raising the mould out of the bath when required.
The deposited metal may be inspected during the process of deposition by
drawing off and returning the solution to the depositing vat by lowering and
raising a cistern or barrel connected to the bottom of the vat by a flexible hose.
The vats, in cases where the mould-shafts are inclined, are sometimes made
V-shaped in cross-section, with the walls at right-angles to the mould spindles.
Figure 8 illustrates a convenient apparatus for use in electro-depositing on the
mould a coating of palladium or chromium.
K is a steam jacketed pan, lined with lead or other suitable anode to contain the
palladium solution. This pan is supported upon a ram L which can be raised and
lowered hydraulically or by screw-gearing or otherwise, to bring the solution which
the pan contains, into contact with the mould B, which is independently supported
from posts or standards N.
In the drawing we have shewn the ram L screw-threaded, so that it can be

page_text: raised and lowered by a nut M carried in a pedestal O adapted to encircle the
ram.
The posts or standards N are placed around the pan and the mould is supported,
while immersed in the palladium or chromium solution, by means of links N¹ or
hinge-attachments carried by the said posts and engaging with eye-bolts or hooks N*
provided on the mould. Two spare standards may be arranged in such a position
relatively to the pan K that by simply turning the mould about the other standard,
as about a hinge, it will be inverted and be received upon the said spare standards
in a convenient position for inspection or treatment. By employing the pan K,
which conforms approximately to the shape of the mould, only a comparatively
small quantity of solution need be used, because when the pan is elevated into the
position shewn in Figure 8 the mould enters the solution and causes its level to
rise in the pan by displacement and to effectually cover the entire surface of the
mould.
It is obvious that by the process hereinbefore set forth the different parts of the
reflector can be made of various thicknesses by the process of "stopping off" or by
other suitable means.
The palladium or alloy of the same may if desired be applied to the reflector
in the form of an amalgam, in the same way, that mercurial gilding is done.
Instead of arranging the moulds in the depositing tanks with their curved
surfaces uppermost as shewn in Figures 1 to 7 they may be inverted and be
In this case we
revolved by means of shafts suspended from overhead brackets.
may dispense with the dome shaped anodes E and the burnishing devices and
depend merely upon the skin friction existing between the surface of the
revolving mould and the electrolyte to effect the required amount of burnishing.
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. The manufacture of reflectors substantially as shewn and described whereby
the extensive polishing treatment of the reflecting surface is avoided.
2. The manufacture of reflectors, consisting in first depositing a film of wax on
a suitable mould, then chemically depositing on such wax film a coating of silver
which is treated to a burnishing or rubbing operation to polish it, then applying
by electro-deposition a coating of palladium to the polished silver coating while
the latter is still on the mould, then applying also by electro-deposition a backing
of copper or other suitable metal to the palladium coating and at the same time
revolving the mould, and afterwards heating or chemically treating the reflector
when removed from the mould, all substantially as and for the purposes specified.
3. In the manufacture of reflectors the rubbing burnishing or polishing
operation to which the silver, deposited on the mould, is subjected prior to the
subsequent electro-deposition of a metal thereonto substantially as described and
for the purpose specified.
4. In the manufacture of reflectors, subjecting the coating or coatings on the
mould to a burnishing operation during the electro-deposition of the copper or
other metallic backing, the said burnishing being effected by the means substantially
as described with reference to the accompanying drawings and for the purpose
specified.
5. In the manufacture of reflectors the use of mandrels or moulds produced
from a mixture of sulphur and plumbago substantially as described.
6. The apparatus or appliances for use in the manufacture of reflectors,
substantially as described with reference to the accompanying drawings.
Tanu 1806
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicants.