IMPROVEMENTS IN APPARATUS FOR SILVERING MIRRORS, PLATE, AND OTHER GLASS
Year: 1876

page_text: LETTERS PATENT to James Edmondson Pratt, of Clifton Lodge, Flodden Road,
Camberwell, in the County of Surrey, Glass Silverer, for the Invention of
"IMPROVEMENTS IN APPARATUS FOR SILVERING MIRRORS, PLATE, AND OTHER
GLASS."
Sealed the 30th May 1876, and dated the 24th March 1876.
PROVISIONAL SPECIFICATION left by the said James Edmondson Pratt at
the Office of the Commissioners of Patents on the 24th March 1876.
JAMES EDMONDSON PRATT, of Clifton Lodge, Flodden Road, Camberwell, in the
County of Surrey, Glass Silverer. IMPROVEMENTS IN APPARATUS FOR SILVERING
+6
MIRRORS, PLATE, AND OTHER GLASS."
My Invention relates to the process of silvering glass for mirrors by the use of
nitrate of silver solutions. In this process as heretofore carried out the glass is
placed upon a horizontal table or bench, and the solution is poured upon it and
spread over the surface of the glass. Now according to my present Invention
I effect the uniform distribution of the solution over the glass by so constructing
the table or bench on which the glass is placed that when the solution has been
poured upon one side of the sheet of glass the table can be tilted over or rocked, so
as to cause the solution to run uniformly over the whole surface of the sheet. For
this purpose I mount the table or bench either upon trunnions in the middle or
near one end of its length, or on a ball-and-socket joint at the centre of its under
side, so that when the solution is poured upon the glass on the bench at one point
the latter may be tilted or rocked on its trunnions, or lowered at one end, or turned
to any angle in any direction on the ball-and-socket joint, so as to cause the
solution to flow uniformly over the whole surface of the glass. By preference I
support the bench upon trunnions or on a shaft at its middle, so that it is balanced
on either side of its support, whereby if a small amount of motion is imparted to
it, it will continue to rock from side to side for some time without requiring any
fresh impulse, thus causing the silvering solution to flow alternately from one side
to the other on the glass.
The extent of motion of the bench may be limited by connecting it at each
end by india-rubber bands to fixed points on the framing supporting the bench.
For silvering by the cold process the bench may be of wood, but for silvering
by the hot process I make the same of metal, and I heat it from below, either by

page_text: jets of gas or by hot water or steam made to circulate through a double bottom or
through a coil of pipes.
For preventing the silvering solution from flowing off the bench I provide the
latter firstly with hinged rims or stops round its edges, which rims may be of wood
covered with vulcanised india-rubber or leather; these stops are held in position
by clips when the solution is being applied, the joint being made water-tight by
the india-rubber, and they are afterwards folded down so as to allow the solution
to flow off the bench into a trough formed round the edges of the table, and also
to allow of the washing of the silver coating formed on the glass.
I also provide moveable rims or stops, which are secured at any point on the
surface of the bench in order to confine the solution within desired limits in cases
when the glass to be silvered is smaller than the bench, so as to prevent any wasto
of the solution. These moveable stops are by preference made of a trough form,
being pressed down by weights placed inside them, and having strips of india-
rubber on their under side and ends to make a water-tight joint; they are secured
at each end to the hinged stops by means of spring clips.
The above described improved construction of hinged or rocking benches may
also be utilized to facilitate the placing of large plates of glass upon them without
danger of fracture by arranging the bench for this purpose to turn up to a con-
siderable angle so as to receive the glass plate, which is brought to it in the usual
upright position in slings, the bench being then turned down again to the horizontal
position with the glass plate upon it.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said James Edmondson Pratt in the Great Seal Patent Office on tho
16th September 1876.
JAMES EDMONDSON PRATT, of Clifton Lodge, Flodden Road, Camberwell, in the
County of Surrey, Glass Silverer. "IMPROVEMENTS IN APPARATUS FOR SILVERING
MIRRORS, PLATE, AND OTHER GLASS."
My Invention relates to the process of silvering glass for mirrors by the use of
nitrato of silver solutions. In this process, as heretofore carried out, the glass is
placed upon a horizontal table or bench, and the solution is poured upon it and
spread over the surface of the glass. Now according to my present Invention I
effect the uniform distribution of the solution over the glass by so constructing the
table or bench on which the glass is placed that when the solution has been poured
upon one side of the sheet of glass the table can be tilted over or rocked so as to
cause the solution to run uniformly over the whole surface of the sheet. For this
purpose I mount the table or bench either upon trunnions in the middle, or near
one end of its length, or on a ball-and-socket joint at the centre of its under side,
so that when the solution is poured upon the glass on the bench at one point the
latter may be tilted or rocked on its trunnions, or lowered at one end, or turned to
any angle in any direction on the ball-and-socket joint, so as to cause the solution
to flow uniformly over the whole surface of the glass. By preference I support the
bench upon trunnions or on a shaft at its middle, so that it is balanced on either
side of its support, whereby if a small amount of motion is imparted to it it will
continuo to rock from side to side for some time without requiring any fresh
impulse, thus causing the silvering solution to flow alternately from one side to the
other on the glass.
The extent of the motion of the bench may be limited by connecting it at each
end by india-rubber bands to fixed points on the framing supporting the bench.
For silvering by the cold process the bench may be of wood, but for silvering by
the hot process I make the same of metal, and I heat it from below either by jets of
gas, or by hot water or steam made to circulate through a double bottom or through
a coil of pipes.

page_text: DESCRIPTION OF THE DRAWINGS.
Fig. 1 of the accompanying Drawings shews a sido clevation, Fig. 2 a plan
partly in section, and Fig. 3 an end elevation of one arrangement of my before-
described rocking bench, and Fig. 4 shews a part transverso section to an enlarged
scale.
The bench consists of an iron table A having a wood trough B fixed round its
edges, and supported on bearers C which are mounted on a spindle D carried
centrally beneath the bench by standards E. The bench A being thus balanced
upon the spindle D it can readily be made to rock backwards and forwards upon
the same to any desired angle, so as to cause the silvering solution to flow back-
wards and forwards upon the plate or plates of glass placed upon the same.
.
For the purpose of readily placing large plates of glass upon or removing them
from the bench without danger of fracture the bench is capable of being tilted up to
a considerable angle, as indicated by the dotted lines in Fig. 3, so that the glass
plate which is carried to it in a vertical position in slings in the usual manner can
be readily leant against the bench when in such inclined position, after which the
bench is turned together with the glass into the horizontal position. A pit F is
formed in the floor to allow of the bench being tilted up as described. The bench
is heated by means of gas jets G, G, below. In order to retain the silvering solution
upon the table this is provided round its edges with hinged rims or stops H, which
may be of wood covered with vulcanised india-rubber or leather; the stops are held
in position by clips M when the solution is being applied, the joint being made
water-tight by the india-rubber, and they are afterwards folded down so as to allow
the solution to flow off the bench into the troughs B, and to allow the silver coating
on the glass to be readily washed afterwards.
Moveable rims or stops I are also provided, which may be secured at any point
on the bench, as indicated at Fig. 2, in order to confine the solution within certain
limits, and thus prevent waste when the plate or plates of glass do not extend over
the whole surface of the bench. These moveable stops are by preference made of a
trough form, being pressed down on the bench by weights placed inside them, and
having strips of vulcanised india-rubber on their under side and ends to make a
water-tight joint. They are secured at each end to the hinged stops H, or to each
other by means of spring clips N.
Figs. 5, 6, and 7 shew respectively a side elevation, a plan, and an end elevation
of another arrangement of my rocking bench as adapted to the frame now used for
the fixed benches, and Fig. 8 shews an enlarged part transverse section of the bench.
In this case the bench A is only capable of rocking sufficiently upon its spindle D
to cause the silvering solution to flow backwards and forwards over the glass, as
before described. The bench is in this case heated by steam made to circulate
through the pipes K situated in the water tank L immediately below it.
The other parts of the bench are similar to those described with reference to
Figs. 1 to 4, and are designated by the same letters of reference.
Having thus described the nature of my Invention, and in what manner the same
is to be performed, I claim,―
First. The use for silvering mirrors and other glass of a bench arranged to rock
or to assume an inclined position upon its support, substantially as and for the
purposes herein described.
Second. The use, in combination with such rocking benches, of hinged and
inoveable stops or rims, substantially as and for the purposes herein described.
In witness whereof, I, the said James Edmondson Pratt, have hereunto set my
hand and seal, this Sixteenth day of September, in the year of our Lord One
thousand eight hundred and seventy-six.
J. E. PRATT. (L.S.)