IMPROVEMENTS IN GRINDING AND POLISHING LENSES
Year: 1852

page_text: LETTERS PATENT to James Stevens, of Birmingham, in the
County of Warwick, Glass Manufacturer, for the Invention of
"IMPROVEMENTS IN GRINDING AND POLISHING LENSES."
Sealed the 7th June 1853, and dated the 16th December 1852.
PROVISIONAL SPECIFICATION left by the said James Stevens at
the Office of the Commissioners of Patents, with his Petition,
on the 16th December 1852.
I, JAMES STEVENS, of Birmingham, in the County of Warwick,
5 Glass Manufacturer, do hereby declare the nature of the said Inven-
tion for "IMPROVEMENTS IN GRINDING AND POLISHING LENSES" to be as
follows:-
I employ a flat disc of metal, wood, or stone, and on the upper
surface of the same I cut a circular groove all round at a little
O distance from the edge. The section of this groove is to be the same
as that of the convexity of the lenses required, but of course larger.
This disc revolves horizontally on a spindle. I then place any
number of lenses, already cast in the ordinary manner, on the ends

page_text: of a corresponding number of spindles, by means of pitch or
cement, and inserting the convexity of the lenses into the con-
cavity of the groove, I cause the disc and the lenses to revolve in
opposite direction. The spindles carrying the lenses having an
elbow or crank, the lenses are caused to diverge from the from the
horizontal line in revolving, and thereby is produced the peculiar
oscillating revolution necessary for grinding a convex surface. The
portion of the disc within the ring or groove consisting of a flat
surface, I employ for grinding the flat surfaces of the lenses.
SPECIFICATION in pursuance of the conditions of the Letters
Patent, filed by the said James Stevens in the Great Seal
Patent Office on the 16th June 1853...
TO ALL TO WHOM THESE PRESENTS SHALL COME, I,
JAMES STEVENS, of Birmingham, in the County of Warwick, Glass
Manufacturer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Sixteenth day of December, in the
year of our Lord One thousand eight hundred and fifty-two, in
the sixteenth year of Her reign, did, for Herself, Her heirs and
successors, give and grant unto me, the said James Stevens, Her
special licence that I, the said James Stevens, my executors,
administrators, and assigns, or such others as I, the said James
Stevens, my executors, administrators, and 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 "IMPROVEMENTS IN GRINDING AND POLISHING
LENSES," upon the condition (amongst others) that I, the said James
Stevens, by an instrument in writing under my hand and seal,
should particularly describe and ascertain the nature of the said
Invention, and in what manner the same was to be performed, and

page_text: 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 James Stevens, do hereby
declare the nature of my 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 Draw-
ings hereunto annexed, and to the letters and figures marked thereon
(that is to say):
My Invention consists of improved apparatus or machinery to be
employed in grinding and polishing lenses, such, for instance, as tkc
lenses required for railway signal lamps.

page_text: also two upright pegs (I, I) on the plate (R), taking into the forks
in the arms (O). To the under-side of this plate (R) the lens (having
been previously cast into form in a common mould) is attached by
means of pitch or cement. The standard (M), bolted to the bed
plate (A), supports the shaft (K) in the bearings at (N). The
lower end of this shaft terminates in a cone, turning freely in a
hollow in the block (P). On the upper end of the shaft, is the
second driving pulley (J), and above it on the same shaft is fixed
On the
the dish (I), which may be made of metal, wood, or stone.
upper surface of this dish a groove is cut, entirely round, of the
form shewn in section at (I¹). This groove should be as nearly as
possible of the same curve as the lens; so that when the lenses on
the ends of the spindles (E) are in the position shewn at (L), they
may as nearly as possible fit the groove. The various parts of the
lens holder marked (S, O, O¹, T, and R), not being fixed, but
working loosely in each other, admit of a certain amount of oscilla-
tion, and impart to the lens a motion slightly out of the horizontal
line, which is necessary to reduce any irregularities in the convex
surface of the lens.
"
Figures 2, 3, and 4, shew another form of lens holder that may
be attached to the spindle (E). It consists of a plate (R¹), through
which the upper ends of the rods (V) are fixed, the lower ends of
the rods terminating in bosses working loosely in the hollows (V¹)
in the under plate (R). The lens is attached to this lower part
in the same manner as to the holder before described.
The apparatus is set in motion by driving bands on the pulleys
(G, and J), by which the dish (I) on the shaft (K) is caused to
revolve in one direction, whilst the pulley on the shaft (H), by means
of the toothed wheel on the same shaft gearing into the wheels on
the spindles (E), causes them to revolve; thus each lens revolves
on its own axis, and the dish also revolving, a true convexity is
obtained.
Having thus described the nature of my said Invention, and in
what manner the same is to be performed, I wish it to be clearly
understood that what I claim is, the arrangement, combination, and

page_text: adaptation of the various mechanical parts, herein-before set forth
and described, for the purpose of grinding and polishing lenses.
In witness whercof, I, the said James Stevens, have hereunto
set my hand and seal, this Fourteenth day of June, in the
year of our Lord One thousand eight hundred and fifty-
three.
JAMES (L.S.) STEVENS.