IMPROVE- MENTS IN GRINDING AND POLISHING GLASS
Year: 1864

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields,
in the County of Middlesex, Gentleman, for the Invention of "IMPROVE-
MENTS IN GRINDING AND POLISHING GLASS." -A communication from abroad
by Eloi Eugène Narcisse Derogy, of Paris, in the Empire of France.
Sealed the 15th November 1864, and dated the 18th June 1864.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson at
the Office of the Commissioners of Patents, with his Petition, on the
18th June 1864.
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of
Middlesex, Gentleman, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN GRINDING AND POLISHING GLASS," a communication to me
from abroad by Eloi Eugène Narcisse Derogy, of Paris, in the Empire of
France, to be as follows:-
This Invention relates to the grinding and polishing of concave and convex
articles of glass, and consists essentially in the rubbing of one glass over or
against the other, whereby both concave and convex glasses may be ground
or polished simultaneously by mutual attrition, in lieu of grinding and
polishing such glasses separately by direct frictional contact with the metal of
the matrices, as heretofore practised.
In carrying out this Invention the pieces of glass, the surfaces of which are
intended to be convex, are secured in the usual manner by cement or pitch to

page_text: the surface of a convex curved metal holder, such pieces of glass having been
previously roughed out to a proper form. To the interior of a hollow or
concave metal matrix are also secured by cement those pieces of glass which
are intended to have concave surfaces, the curves of the two tools agreeing
with each other. Emery powder and water, or any other suitable grinding
or polishing-materials, are now introduced into the hollow matrix upon the
glass fixed therein, and the convex tool, with its glasses fixed thereon, is
introduced into the matrix, so as to bring the surfaces of the two sets of
glasses in contact, and by imparting a suitable rotatory motion to one or both
the holders or tools, the glasses will be ground by their attrition against each
other; the one set having a convex and the other a concave surface ground
or polished thereon simultaneously. If both sides are to be ground or
polished, the glasses must be removed and reversed on their holders, and the
operation of grinding or polishing continued as before.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Henry Johnson in the Great Seal Patent Office on the
14th December 1864.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eighteenth day of June, in the year of our Lord One
thousand eight hundred and sixty-four, in the twenty-seventh year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said John Henry Johnson, Her special license that I, the said John Henry
Johnson, my executors, administrators, and assigns, or such others as I, the
said John Henry Johnson, my executors, administrators, or assigns, should
at any time agree with, and no others, from time to time and at all times
thereafter during the term therein expressed, should and lawfully might
make, use, exercise, and vend, within the United Kingdom of Great Britain
and Ireland, the Channel Islands, and Isle of Man, an Invention for "Im-
PROVEMENTS IN GRINDING AND POLISHING GLASS," a communication to me from
abroad by Eugene Narcisse Derogy, of Paris, in the Empire of France,
upon the condition (amongst others). that I, the said John Henry Johnson,
my executors or administrators, by an instrument in writing under my hand
and seal, or under the hand and seal of one of them, should particularly

page_text: describe and ascertain the nature of the said Invention, and in what manner
the same was to be performed, and cause the same to be filed in the Great
Seal Patent Office within six calendar months next and immediately after
the date of the said Letters Patent.
NOW KNOW YE, that I, the said John Henry Johnson, do hereby
declare the nature of the said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the
following statement, reference being had to the accompanying Drawings, and
to the letters and figures marked thereon, that is to say :-
The said Invention relates to the grinding and partial polishing of concave
and convex articles of glass, and consists essentially in the rubbing of one
glass over or against the other, whereby both concave and convex glasses may
be ground or partially polished simultaneously by mutual attrition, in lieu of
grinding or partially polishing such glasses separately by direct frictional
contact with the metal of the matrices, as heretofore practised.
In carrying out this Invention the pieces of glass, the surfaces of which are
intended to be convex, are secured in the usual manner by cement or pitch
to the surface of a convex curved metal holder, such pieces of glass having
been previously roughed out to a proper form. To the interior of a bollow or
concave metal matrix, are also secured by cement those pieces of glass which
are intended to have concave surfaces. Emery powder or any other suitable
grinding materials are now introduced into the hollow matrix upon the glass
fixed therein, and the concave tool, with its glasses fixed thereon, is intro-
duced into the matrix, so as to bring the surfaces of the two sets of glasses in
contact, and by imparting a suitable rotatory motion to one or both the
holders or tools the glasses will be ground and smoothed by their attrition
against each other; the one set having a convex and the other a concave
surface ground thereon simultaneously. If both sides are to be ground the
glasses must be removed and reversed on their holders, and the operation of
grinding continued as before.
And in order that the said Invention may be fully understood, I shall now
proceed more particularly to describe the same, and for that purpose I shall
refer to the several Figures on the Sheet of Drawings hereunto annexed,
the same letters of reference indicating corresponding parts in all the
Figures.
According to the method at present adopted for grinding convex and
concave glasses, the glasses having been first roughed out to the curve
required, are, if of a convex form, placed side by side in the metal cup A,
Fig. 1, and each glass is covered on the upper surface with cement.
The

page_text: convex surfaces of the glasses are placed in contact with the interior of the
cup, the curve of which corresponds exactly with the curve to be finally given
to the glass. The convex curved wrought-iron block B (Fig. 2), previously
heated, is now introduced into the cup A and pressed upon the cemented
surface of the glasses contained therein, whereby they are caused to adhere to
the block B, and when the cement has cooled will be held firmly thereto.
The cup and the block are then generally reversed, and the grinding is com-
menced by turning either by hand or by machinery for the purpose the
cup A upon the glass on the block B; the cup being usually composed of
bronze, and containing emery powder suited for the purpose.
Fig. 3 represents a sectional elevation of the whole of the parts, a repre-
senting the layer of cement, and 6 the pieces of glass to be operated upon.
The grinding is continued for one or two hours, using emery powder of
different numbers or degrees of fineness as the operation proceeds. In
grinding concave glasses the same operation is carried on by the aid of the
tools A and B shown in section at Figs. 4 and 5 respectively. In this case
it is the block B which is cup shaped, whilst the grinding surface A is of a
convex form. It is upon the surface A that the glasses are disposed and
coated with cement on their outer surfaces, whereupon they are made to
adhere firmly to the interior of the cup-shaped block B by pressing it whilst
heated on to the cemented surface of the glasses. Fig. 6 shews the best
position of the parts during the grinding. In both these cases it will be seen
that the grinding is effected by the rubbing of the glass against the bronze
surface A, the tool or block B acting simply as a holder for the glass.
Now, according to my present Invention, the attrition of glass against glass
is substituted for the attrition of glass against metal, whereby I am enabled
to grind two surfaces of glass simultaneously, the one being ground concave
and the other convex. For this purpose I take the block B, (Fig. 7,) having
the glass which is to be ground to a convex form cemented thereon, as is
well known in the trade, and I also take the cup A and cement into the
interior thereof the glass which is to be ground to a concave surface, and I
rub the two glass surfaces together, so as to grind them by mutual attrition,
using emery powder during the operation. The same force employed and the
same quantity of emery will thus produce a double effect in the same time
that it is required to grind only one surface by the existing method.
Having now described and particularly ascertained the nature of the said
Invention, and the manner in which the same is or may be used or carried into
effect, I would observe in conclusion that what I consider to be novel and original
and therefore claim as the Invention secured to me by the herein-before in

page_text: part recited Letters Patent is, the grinding and partial polishing of convex
and concave glasses simultaneously at one operation by the mutual attrition
of the glasses to be ground substantially as herein-before described.
In witness whereof, I, the said John Henry Johnson have hereunto
set my hand and seal, the Fifth day of December, One thousand
eight hundred and sixty-four.
J. HENRY JOHNSON. (L.S.)
J. HENRY JOHNSON. (LS.)