IMPROVEMENTS IN THE MANUFACTURE OF LENSES
Year: 1852

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALFRED
VINCENT NEWTON, of the Office for Patents, 66, Chancery Lane, in the
County of Middlesex, Mechanical Draughtsman, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of Great Britain, bearing
date at Westminster, the Seventeenth day of April, in the fifteenth year
of Her reign, did, for Herself, Her heirs and successors, give and grant
unto me, the said Alfred Vincent Newton, Her especial license, full power,
sole privilege and authority, that I, the said Alfred Vincent Newton, my
exors, adiñors, and assigns, and such others as I, the said Alfred Vincent
Newton, my exors, admors, or assigns, should at any time agree with, and
no others, from time to time and at all times during the term of years therein
expressed, should and lawfully might make, use, exercise, and vend, within
England, Wales, and the Town of Berwick-upon-Tweed, and in all Her
Majesty's Colonies and Plantations abroad, and in the Islands of Jersey,
Guernsey, Alderney, Sark, and Man, an Invention of "IMPROVEMENTS IN THE
MANUFACTURE OF LENSES," being a communication from abroad; in which said
Letters Patent is confained a proviso obliging me, the said Alfred Vincent
Newton, by an instrument in writing under my hand and seal, particularly
to describe and ascertain the nature of the said Invention, and in what manner

page_text: the same is to be performed, and to cause the same to be inrolled in Her
Majesty's High Court of Chancery within six calendar months next and
immediately after the date of the said in part recited Letters Patent, as in
and by the same, reference being thereunto had, will more fully and at large
appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Alfred Vincent Newton, do hereby declare that the nature of the said
Invention, and the manner in which the same is to be performed, is
particularly described and ascertained in and by the following description
thereof, reference being had to the Drawings hereunto annexed, and to the
letters and figures marked thereon (that is to say) :-
:-
The following details, as prepared by the Inventor, will set forth clearly the
nature and object of his improvements. The dioptric lens heretofore and at
the present time in use for sea lights and for other lights requiring great
intensity, being constructed of single zones or rings made up of segments
according to the diameter of the required lens, has induced a belief that glass
could not be prepared without incurring the expence of grinding and polishing
the curved surface, and that economy dictated a method of manufacture
embracing a centre and zones or segments. An examination into the
necessity daily shewn for the more general use of a dioptric lens to the
purpose of a sea light, including under that name either revolving or stationary
coast light, bay light, bar light, ship signal light, deck and between-deck light,
port light, and all other lights for ships, tide light, floating light, and coast,
harbor, and river light generally, and also a land light, including under that
name railway locomotive light, carriage light, ferry light, and as applied to
architectural purposes, and, in fact, to any purpose where an intensity of light
is required, induced the Inventor to examine the method of construction of the
'built-up lens," and essay at least to reduce the expence without reducing the
strength of the light. Commencing with the suggestions of Buffon, that a
spherical body from its thickness absorbs light in proportion to its density,
and that a sectional figure of any required shape and thickness could be
cast of vitrified material or glass, and ground in steps or concentric zones to
produce a lens (as executed with partial success by the Abbé Rochon), from
the expence incidental to the accuracy required in-grinding and polishing the
steps or zones, although the Inventor could fully appreciate the lens of Buffon,
he considered it was beyond the reach of the million by reason of the cost.
The experiments of the Abbé Rochon were, however, useful in preparing the
way for the manufacture of the dioptric lens in separate pieces, which was
"

page_text: subsequently accomplished by the ingenious Fresnel, after the suggestions of
Condorcet, known as the "annular band lens," at the present time in use
in several lighthouses, in which the spherical aberrations are nearly connected
by making the foci of each zone to coincide. Although of great utility, the
enormous expense of making the "annular band lens" of Fresnel, in which
not only each separate piece must have its surfaces formed with great
accuracy, but all the several pieces must be fitted to each other, so that
when put together they shall constitute a perfect whole, has limited the use
of this otherwise valuable and desirable invention to a very few localities.
The object of this Invention is to produce a dioptric lens which shall present
all the practical advantages of the annular band lens of Fresnel, and at so
cheap a rate as to permit of its being applied to all purposes requiring
intensity of light. And to this end the Invention consists in a new
manufacture of dioptric lenses made in one or several pieces moulded and
pressed to the form required for the surfaces, and when made in several
pieces, the required fit of the several parts being produced by giving the
reversed required form to the metal moulds, in which the molten glass is to
be put, and into and by which it is to be pressed, the pressure to be applied
being sufficient to produce the required surfaces and angles. The mode of
procedure which has been adopted with success is as follows, reference being
had to the accompanying Drawings, making part of this Specification, and
marked Nos. 1, 2, and 3.
In the accompanying Drawings, No. 1, a represents a circular mould to
receive the melted glass. b is a follower which rests on the mould, as shewn
at b, b. c is a plunger which fits into the follower b, and which is intended
to spread the melted glass uniformly into the mould a by pressure. This
construction of mould, plunger, and follower, and the mode of their working, are
well known to glass manufacturers. The mould may be made of any figure
required, and the follower and plunger will be made to correspond with the
mould. The mould a, instead of having the concentric central lens and rings
as shewn, may present a plain surface and the melted glass laid thereon, and
the follower placed as herein-before described. The plunger c, having
on it the rings and figures as shewn in the mould a, by pressure upon the.
melted glass, as already described, will produce the required figure. The
shape of the mould, may be changed to any figure, whether convex or
concave, with the central zones or rings. d is a section at a taken at the
dotted lines e, f, and shows in section the figure of a lens. The mould,
instead of being made in one piece, as shewn at a, d, may be made sectionally

page_text: of as many separate rings or zones as there are designed to be rings or zones
in the lens, or otherwise sectionally divided according to convenience, a
suitable allowance in the diameter of each being made for the increased
aggregate diameter by reason of the parts being distinct; and in such cases
the moulds for the separate rings and zones being laid together and secured
in their proper order will form the entire mould, while the interstices left
between the separate pieces will answer the same purpose as the holes at the
angles of the zones subsequently described, (viz.,) to suffer the air to escape
when the pressure is applied. If it should be desired (as it may be in the
case of very large lights) to cast the lens itself in sections, the several sections
may be moulded and pressed as described above, and then the whole cemented
together in the usual way. 9 shews a concentric dioptric lens corresponding
with the mould a, and is set in a frame ready for use; the frame may be
made of any suitable metal.
No. 2, h, shews in perspective a six-sided lantern, of which i is a sectional
view taken at 2, ; each side contains a lens having a convex centre, and
several sections of zones or rings. k shews a figure made in three pieces
k, ka, k³, which will require three separate moulds, or the whole may be cast
together in one mould. Any required number of lenses may be combined
together after the manner shewn at h. The several lenses to make up the
required figure may be set in a metal frame; the cap 1 may vary in shape and
may be made of any suitable metal.
No. 8 shows a dioptric cylinder m applicable to the purposes of a lantern
containing several zones or rings of regular and irregular widths, which can be
varied at pleasure, and may be manufactured of any length or circumference.
n shew's a transverse vertical section of m as applied to the purposes of a
hanging or hand lantern with a stand lamp top, and ring attached.
If required
each lens may be made with one or many zones or concentric rings according
to the diameter, the lens or segment of a lens being produced, as shewn and
described, by pressure in a mould with or without fire polishing, a process well
known among glass workers. To promote focal intensity and to prevent the.
absorption of light, it will be obvious that each lens should be manufactured
as thin as the size and number of concavities and convexities will permit. It
is not essential to lay down any rule for thickness or for the size, as the
intensity will be decreased by density, and that therefore the thickness will be
governed by the extent of surface required. In the making of dioptric lenses
sharpness at the angles of the zones is of the utmost importance, and to effect
this object it may be found necessary to form in the angles of the moulds

page_text: apertures (so small as to be nearly invisible to the naked eye) for the escape
of air from the cavities of the mould, otherwise atmospheric air may be
confined in such cavities, and when pressure is applied the air thus confined
will prevent the glass from entering and assuming the required form of the
sharp angles of the mould. The holes should be very small and sufficiently
numerous to insure the escape of the air. When that part of the mould
which forms the curved surfaces of the zones is made in sections, sufficient
space can be left between the different zones for the escape of the air. In
manufacturing the dioptric lenses, metal moulds are used having the reverse
of the figure to be produced, and which will require accuracy in construction
and finish. The melted glass, being prepared in the usual way known to glass
workers, is to be put into the mould, and the same process or labor is
required in producing a lens as is observed in moulding, by pressure, any other
article from melted glass. The quality of the glass is not essential, but as
light is always lost even in passing through the most transparent body, it will
be more economical as well as more useful to employ a good quality of glass
and as white as possible, as white glass will permit the more free passage of
light, and with more brilliancy than an inferior quality and of a less whiteness.
In describing the Invention as a manufacture and its adaptation to the various
uses herein-before mentioned, it is not essential to detail the peculiar way in
which sea lights are used, nor the adaptation of the dioptric lens to the several
purposes spoken of other than sea lights, nor the many-sided lanterns, whether
stationary or revolving, in use, nor the peculiar shape of the case or shell, nor
the lamp, nor the many ways in which light may be refracted, as any person
essaying to use or manufacture the dioptric lens will be prepared with the
necessary means; it is, therefore, considered unnecessary to detail in words or
to show in the Drawings the manner of constructing the different kinds
of apparatus in use for that purpose.
Having now described the Invention of "Improvements in the Manufacture
of Lenses," as communicated to me by my Foreign Correspondent, I wish it to
be understood that under the above in part recited Letters Patent I claim the
manufacture of dioptric lenses of glass in one or more pieces by pressure in
metallic moulds substantially as specified.
In witness whereof, I, the said Alfred Vincent Newton, have hereunto
set my hand and seal, this Sixteenth day of October, in the year of
our Lord One thousand eight hundred and fifty-two.
(L.S.) A. V. NEWTON.

page_text: AND BE IT REMEMBERED, that on the Sixteenth day of October, in the
year of our Lord 1852, the aforesaid Alfred Vincent Newton came before
our said Lady the Queen in Her Chancery, and acknowledged the Specifi-
cation aforesaid, and all and every thing therein contained and specified, in
form above written. And also the Specification aforesaid was stamped
according to the tenor of the Statute made for that purpose.