IMPROVEMENTS IN LENSES, AND IN THE MEANS EMPLOYED FOR MANUFACTURING THE SAME.
Year: 1876

page_text: LETTERS PATENT to James Couper, the younger, and William Haden Richardson,
both of Glasgow, in the County of Lanark, North Britain, Flint Glass
Manufacturers, for the Invention of "IMPROVEMENTS IN LENSES, AND IN THE
MEANS EMPLOYED FOR MANUFACTURING THE SAME.'
Sealed the 1st September 1876, and dated the 11th July 1876.
PROVISIONAL SPECIFICATION left by the said James Couper and William
Haden Richardson at the Office of the Commissioners of Patents on the 11th
July 1876.
"
JAMES COUPER, the younger, and WILLIAM HADEN RICHARDSON, both of Glasgow,
in the County of Lanark, North Britain, Flint Glass Manufacturers. IMPROVE-
MENTS IN LENSES, AND IN THE MEANS EMPLOYED FOR MANUFACTURING THE
SAME.
This Invention which relates to improvements in lenses of the dioptric class, such
as are used for ships, port, starboard, and mast head lights, and for other analagous
purposes, has especial reference to those lenses of the class referred to which are
formed of moulded as distinguished from cut glass.
The object of the Invention is to impart a greater diffusive power to the lens, to
save glass in the manufacture thereof, and thereby to cheapen, the cost of manu-
facturing such lenses.
The improvement in lenses whereby their power of diffusion is increased, consists
in forming the several dioptric prisms surrounding the central convex portion of a
gradually increasing depth or thickness from the inner towards the exterior prism,
that is to say, that each succeeding prism proceeding from the centre outwards is
thicker, or projects more than the prism which precedes it. Thus the lens becomes
so shaped that a line drawn across it touching the axis of the central convex lens
and the apices or ridges of the dioptrie prisms is of a hollow or concave figure or of
a figure whose sides proceeding inwards from the apex of the outer prism form any
desired angle at the axis of the central convex lens.
The improvement in the means for manufacturing such lenses relates to the
construction of the moulds into which the glass is dropped, poured, or placed, for
forming the lens. As the moulds have hitherto been constructed it has been
essential when constructing a lens for a mast head light, for example, to construct
the lens in a complete circle, and afterwards to cut out the third or other portion of
the circle not required.

page_text: According to the present Invention the mould is shaped so that a quantity of
glass equal only to the length of the lens is moulded with a curved form below and
with flat, straight, or inclined sides above, whereby the central block is capable of
being drawn up out of the moulded glass so soon as it is set or partially set. Whilst
still hot a pair of guides are applied to the upper or straight portion of the lens,
which being drawn or pressed towards the centre contract a curve inwards the
upper portions of the lens to the required extent, or the lens may be withdrawn
while hot and flexible, and a paddle or form used for curving the straight
portions. The lens may also be used with its sides straight, that is to say, without
being submitted to the action of guides, "paddles," or forms as above set forth.
"
Lenses whose dioptric prisms are constructed as herein-before described, besides
being used for the purposes herein-before referred to, are also applicable for purposes
generally wherein lenses for diffusing light are employed.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by the
said James Couper and William Haden Richardson in the Great Seal Patent
Office on the 10th January 1877.
JAMES COUPER, the younger, and WILLIAM HADEN RICHARDSON, both of
Glasgow, in the County of Lanark, North Britain, Flint Glass Manufacturers.
IMPROVEMENTS IN LENSES, AND IN THE MEANS EMPLOYED FOR MANUFACTURING
THE SAME."
<5
Our said Invention which relates firstly to improvements in lenses of the dioptric
class, such as are used for ships' mast head, side, and anchor lights, for railway
lights, and for other analogous purposes, has especial reference to those lenses which
are manufactured or formed of moulded glass, but lenses may also be constructed of
cut glass with our improvement applied thereto or embodied therein.
The first part of our said Invention has for its object to impart a greater diffusive
power to the lens.
The improvement whereby the power of diffusion of dioptric lenses is increased,
consists in forming the several dioptric prisms surrounding the central convex
portion of a gradually increasing depth or thickness from the inner to the exterior
prism, that is to say, that each succeeding prism proceeding from the centre out-
wards is thicker or projects more than the prism which precedes it, thus the lens
becomes so shaped that a line drawn across it touching the axis of the central
convex lens, and the apices or ridges of the dioptric prisms is of a hollow or concave
figure, or of a figure whose sides proceeding inwards from the apex of the exterior
prism form any desired angle with the axis of the central convex lens.
The improvements under our said Invention consist, secondly, in the means
employed for manufacturing lenses, and have for their object to save glass in the
manufacture of lenses and to diminish the cost of manufacturing them.
This part of the Invention relates to the construction of the moulds into which
the glass for forming the lens is dropped, poured, or placed. As the moulds have
hitherto been constructed it has been essential when constructing a lens for a mast-
head light for example, to form it in a complete circle and afterwards to cut out
the third or other portion of the circle not required, but according to our present
Invention the mould is so shaped that a quantity of glass equal only to the length
of the lens required is moulded with a semicircular portion below, and with flat,
straight, or outwardly inclined sides above, which construction permits the central
block or plunger to be withdrawn from the mould so soon as the glass forming the
lens is set or partially set. Whilst still hot and when in the mould a pair of guides
are or may be applied to the upper or straight portion of the lens, which being
drawn or pressed together towards the centre contract or curve inwards the upper
portions of the lens to any required extent, or the lens may be withdrawn from
the mould while still hot and flexible or when chilled and placed on a "paddle" forin

page_text: or templates having the required curvature, and the top or straight portions then
pressed or drawn together as above set forth, and as well understood by practical
glass makers.
The lens may also be used with flat, straight, or inclined sides, that is to say, that
the use or application of guides, "padlles" forms, or templates for the purpose of
contracting the straight sides of the lens may be dispensed with.
And in order that our said Invention may be properly understood, we now
proceed more particularly to set forth the system, mode, or manner, in or under
which the same is or may be used or practically carried into effect, reference being
had to the annexed Sheet of Drawings and to the letters and Figures marked
thereon, that is to say :-
On the Sheet of Drawings hereunto annexed Figure 1 is a section of a lens
showing the improved form thereof which constitutes the first part of our improve-
ments herein-before referred to, and of which the part marked A is the central
convex lens, and those marked B, C, D, and E, F, G, respectively on opposite sides of
the central convex portion A, the dioptric prisms which are successively increased in
thickness as they proceed outwards from the central convex lens A to the exterior
prisms G and D, so that a radial, straight, or curved line touching the centre A, also
touches the apices of each of the prisms B, C, D, E, F, G, and in accordance with such
construction greater diffusive power is obtained as herein-before mentioned.
It is to be understood that the section shown at Figure 1 is not only that of
a lens of a circular or other curved segment, but is also that of a round lens with
a flat back.
At Figure 2 of the Drawings is shewn in vertical section at Figure 3 in plan,
and at Figure 4 in transverse vertical section, a mould constructed in accordance
with the second part of our Invention for moulding lenses whose segment is more
than that of a semicircle. It consists of a sole or bed plate H of a circular or
other form, and in the centre of which is formed an opening I. Resting upon this
sole or bed plate is the block J, which is provided at its lower end with a projection
corresponding in size and form to the opening in the sole plate H, into which it is
placed, and thereby the block is retained in a fixed position. At the rearward end
of and secured to the sole plate Haby means of bolts a is a vertical plate K, to
about the centre of which, but in a horizontal position, is fixed by means of bolts b
another plate L, which at its extremities is formed with hinges M, to which are
attached doors or sides N, which swing against or bear upon the flat sides of the
block J, and thus form an enclosure into which glass may be dropped, poured, or
placed. At the top of the vertical plate K. a hinge O is formed, to which is
attached by means of corresponding projections the door or frame P. In this door
or frame P is a rectangular opening of sufficient size to allow a plunger Q, by which
the interior shape of the lens is formed and its thickness regulated, to pass through,
but fitting the rectangular opening closely enough to prevent the glass from being
pressed out above the mould at the top side of the plunger Q. Fixed to the
plunger by bolts c is a plate R, and this plate by means of the holes & shewn on
the plan, Figure 3, through which bolts are passed, attaches the plunger to the
lower extremity of the piston rod of an hydraulic or other press, and by which the
plunger is raised out of or lowered into the mould as required. On the front end of
the mould, or that furthest from the vertical plate K, a catch S is centred to one of
the doors N. This catch at its other end is formed with a projection for engaging
with a square stud T, which is fixed to the opposite door or side, but at right
angles to the catch S, and by this means the doors or sides N are held tight against
the flat sides of the block J. To the sole or bed plate there is also centred another
catch U, which stands in a vertical position and also engages with a square stud in
the top door or frame P, thereby holding it tightly down upon the top of the
mould J. When the glass is ready to be poured or dropped into the mould the
plunger is withdrawn, and so soon as the glass is poured or dropped thereinto
the plunger Q is lowered by the hydraulic press or other mechanism to which it is
attached, the effect of which is to squeeze the fluid glass on all sides and cause it

page_text: to rise up and fill the space marked 'X in Figures 2 and 3. So soon as the glass is
set the plunger Q is withdrawn, and the upper part P of the mould opened up, the
catch being loosened to permit of that being done. When the upper portions of
the lens, which are left straight by the form of the plunger P, are to be contracted
in the mould, this is effected by applying, either by hand or by mechanism, two
strips of wood or metal, which catch upon projections left at the upper portions of
the vertical sides of the lens whilst in the mould, and with these pressing inwards
the vertical sides to any required extent. The top of the mould has a series of
parallel lines, or a scale engraved on it, for indicating to the operator the extent of
the contraction. To ensure accuracy in the contraction or curving in of the upper
side portions of the lens a wooden or other block or body of the required size and
curvature may be placed within the lens before contracting it, and which is after-
wards removed.
Having now described and particularly ascertained the nature of our said Inven-
tion, and the system, mode, or manner in or under which the same is or may be.
used or practically carried into effect, we would observė in conclusion that what we
consider to be novel and original, and therefore claim as the Invention secured to
us by the herein-before in part recited Letters Patent is-
First. The lenses having the section shown at Fig. 1 of the appended Sheet of
Drawings, wherein the depth of the prisms increases in a direction proceeding out-
wards from the central convex lens, as herein-before described.
Second. The construction of moulds herein-before described and shewn at
Figures 2, 3, and 4 of the appended Sheet of Drawings, wherein moulded lenses of
a greater segment than a semicircle are produced, and whereby the expense of
cutting segments from a complete circle, as hitherto practised, is avoided, as well as
a saving of glass effected, substantially as herein-before described.
Third. A dioptric lens, consisting of a semicircle terminating with flat, straight,
or parallel sides, as herein-before described and illustrated by the form of the hollow
space X in Figure 2.
In witness whereof, we, the said James Couper, the younger, and William
Haden Richardson, have hereunto set our hands and seals, this Ninth day
of January One thousand eight hundred and seventy-seven.
TAMUS COUPED
VALD
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