IMPROVEMENTS Txt OPTICAL LENGES, AND IN MACHINES FOR MANUFACTURING THE SAME.
Year: 1857

page_text: LETTERS PATENT. to Salomon Sturm, Optician, and Henry Emile Bour,
Gentleman, both of Paris (France), for the Invention of "IMPROVEMENTS
Txt
OPTICAL LENGES, AND
IN MACHINES FOR MANUFACTURING THE SAME.
Sealed the 24th November 1857, and dated the 17th June 1857.
PROVISIONAL SPECIFICATION left by the said Salomon Sturm and
Henry Emile Bour at the Office of the Commissioners of Patents, with
their Petition, on the 17th June 1857.
We, SALOMON STURM, Optician, and HENRY EMILE BOUR, Gentleman, both
of Paris (France), do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN OPTICAL LENSES, AND IN MACHINES FOR MANUFACTURING THE
SAME," to be as follows:
The object of these improvements consist, firstly, in the manufacture of
optical lenses, with cylindrical surfaces, the axis of one surface being situated
in a vertical direction to the axis of the opposite surface; and 2, in the
manufacture, by mechanical means, of optical lenses offering any given curva-
ture or focal length with cylindrical surfaces, the axis of one surface being
situated in a vertical direction to the axis of the opposite surface; and 2, in
the manufacture, by mechanical means, of optical lenses offering any given
curvature of focal length.
For manufacturing lenses with cylindrical surfaces, we prefer using a
mechanical arrangement consisting of a rectangular elongated prism, turning

page_text: by means of a horizontal spindle in a suitable frame, and on which prism are
attached the glasses to be ground; a cup or hollow cylinder segment situated
below the said prism serves for grinding or polishing the glasses which are to
be converted into lenses, for which purpose a reciprocating end motion is given
to the cup, in which latter are introduced the materials used for grinding or
polishing lenses; means are provided for bringing the cup nearer to or farther
from the prism. When we wish to give the glasses any given curvature, we
prefer making use of an arrangement consisting of a strong pendulum
mounted in a suitable frame, the glasses are attached to the underside of the
pendulum, and a small grinding roller travelling over a suitable moveable bed
plate serves for grinding the surfaces of the glasses to the required curvature;
the said grinding roller being guided in its way by suitable bars, or the whole
bedplate receives the required up and down motion by suitable levers, screws,
and gearing. The machines may be driven by hand or by any other suitable
motive power.
*SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Salomon Sturm and Henry Emile Bour in the Great Seal
Patent Office on the 17th December 1857.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, SALOMON
STURM, Optician, and HERNY EMILE BOUR, Gentleman, both of Paris (France),
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Seventeenth day of June, in the year of our Lord
One thousand eight hundred and fifty-seven, in the twentieth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto us, the said
Salomon Sturm and Henry Emile Bour, Her special licence that we, the
said Salomon Sturm and Henry Emile Bour, our executors, administrators,
and assigns, or such others as we, the said Salomon Sturm and Henry 'Emile
Bour, our 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 OPTICAL LENSES,
AND IN MACHINES FOR MANUFACTURING THE SAME," upon the condition (amongst
others) that we, the said Salomon Sturm and Henry Emile Bour, our execu-
tors or administrators, by an instrument in writing under our, or their, or one

page_text: of their hands and seals, should particularly 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 Henry Emile Bour, do hereby declaro
the nature of our said Invention, and in what manner the same is to bd
performed, to be particularly described and ascertained in and by the following
statement:-
It is sufficiently known that lenses or optical glasses of a spherical form
present the great defect of giving rise to what is called in optics the aberration,
which defect cannot be removed even by the most careful manuel workman-
ship; from this reason, ever since the invention of the achromatic glasses,
attempts have been made to manufacture optical glasses in a mechanical way,
which till now was found possible only for spectacle lenses, although in a
rather imperfect manner. It would be superfluous also to state, that the
spherical lenses for spectacles exert a very pernicious effect on the sight.
About thirty years since Chamblant discovered that glasses of a cylindrical
form, on the contrary, do not fatigue the sight in the least, the more so as in
this manner they may receive any required curvature; and although till yet
science had not adopted these lenses, this depended on the great difficulty
incurred in their manufacture; besides that, the least defect they present
makes them fully unsuitable for optical instruments in which a combination
of several lenses is required. We have applied ourselves since a number of
years to the construction of mechanical arrangements, by means of which the
said cylindrical lenses, or by which also lenses presenting any other required
curvature may be manufactured in a mechanical way with regularity and a
mathematical exactitude; we have at last arrived to combine the mechanical
arrangements forming the object of the present Letters Patent.
In the annexed Drawings the Figs. 1, 2, 3, 4, and 5, represent various
views of a machine for manufacturing large quantities at a time of optical
lenses of a cylindrical form, the curvatures of the surfaces of which offer the
utmost preciseness. The Figs. 6, 7, 8, and 9, represent various views and
parts of another arrangement by which lenses of any suitable curvature may
be made, such, for instance, offering elliptical, parabolical, hyperbolical, and
other surfaces. The machine represented in the Drawings is executed on a
scale allowing the manufacture of objective lenses of 3 feet in diameter and
of 30 feet focal length. The importance of having the means of manufac
turing with an almost mathematical correctness lenses of this range will bª

page_text: easily understood; in fact these dimensions of lenses were never expected to
be obtainable, the more so as the smallest deviation from the required curve
on any point of the surface of a lens for an optical instrument in most cases
.renders this latter entirely useless, and one could consequently, not expect to
reach the perfect correctness obtainable only by mechanical labour. An
enormous advantage which the glasses made according to a given curvature
offer consist therein that it allows of increasing considerably the field of vision,
which part in ordinary spherical lenses is generally very limited in comparison
to the surface; by these means a much clearer and more precise sight is
obtained, and it is possible also to distinguish a much greater quantity of
objects at a time.
Scientific men devoted to the production of large optical lenses, such, for in-
stance, as for astronomical purposes, did hitherto consider the manufacture of
the said lenses in a mechanical manner as a problem impossible to be solved,
and it was unquestionable extremely difficult as long as they remained
adhering to the lenses with spherical surfaces. From the very moment, how-
ever, we succeeded in combining mechanical arrangements, by which the
manufacture of lenses, the surfaces of which present a curvature other than a
spherical one, was obtained, and to manufacture such lenses with a mathe-
matical preciseness, and particularly lenses of a cylindrical form, the mecha-
nical manufacture of the said lenses was an immense step towards the
perfection of optical instruments, and this the more so as we found that cylin-
drical lenses ought not to have their generatrixes in a parallel direction in the
same plan, as was the case with the few cylindrical lenses hitherto made, but
that on the contrary, the said generatrixes ought to cross each other at right
angles in two parallel planes. We will now describe the arrangement, and
the mode of acting of the machine represented in the Figs. 1, 2, 3, 4, and 5
of-the annexed Drawings.
Fig. 1, Sheet I., represents a longitudinal external elevation view of the
machine, of which Fig. 3, Sheet II., is a continuation; Fig. 2 is a plan view
of the machine, a continuation of which Fig. is given in Fig. 4, Sheet II.;
Fig. 5, Sheet III., is an end elevation view; corresponding parts are indicated
by the same letters in these various Figures.. The machine consists of a solid
cast-iron frame A, in which fits a casing B, resting on four set screws C,
acting in fixed nuts, by means of which screws the casing may be placed in
any suitable position. To the blank or cylindrical part E of each of these
Ecrews C, is fitted a bevil wheel F, gearing into another bevil wheel F¹ fixed
on the arbor G, provided with a hand wheel Ġ: The up-and-down motion of
this casing B is guided by means of screw bolts II, fixed to the sides or wings

page_text: of the casing, and gliding in vertical slits H¹ cut out in the standards A¹ of.
the frame A, which standards and also the pillars I (four of them on each.
longitudinal side of the machine) are duly fixed to a solid bed-plate I", on.
which rests the entire machine, so as to make the whole perfectly steady in.
its motions; each pair of pillars being connected together by a strong cross
bar I', which cross-bars support the bearings O, in which turns a solid shaft
J. The upper part B' of the casing B has dovetailed or bevilled sides so as<
to serve as a guide for a slide K, permitting to this latter of gliding to and.
fro over the length of the machine, which to-and-fro motion is imparted to.
this slide K by the two connecting rods L, one of these rods being situated:
on each side of the said slide and jointed to the hinder end of this latter,
whereas the other end of the said rods may be attached at any suitable point.
of the surface of a fly wheel M, thus allowing to regulate the length of stroke
of the said connecting rods L, and consequently of the slide K; on this slide.
K a cast-iron cup N is solidly fixed by means of screw bolts. The standards
I are connected together at their upper ends by the cross bars I', on the middle
of the lengths of which cross bars I are fixed the bearings O for the shaft J,..
which latter, by means of a cone pulley P and strap, may receive a rotary
motion from any suitable prime mover, and be furnished with a proper friction
clutch P for transmitting or interrupting the rotary motion. The shaft J
consists of two distinct parts, J and J¹, connected together by a boss R, for
allowing easily to remove the prism S, and replace the same by another; this
prism S, with flat sides T is keyed solidly and in a concentric manner on the
part J; on the sides T of this prism S are screwed metal plates, on which are.
cemented the flat pieces of glass, to be transformed, by grinding, into lenses of
the proper shape; whereas the sand, emery, or other substances made use of..
for this grinding, rubbing, or polishing of the said glasses is put in the cup N.
In order that the glasses may be fixed or cemented in the proper position on..
the plates of the sides T they must be previously suitably prepared, that is to..
have the middle lines of both surfaces of each glass properly marked;
for this purpose, after the flat pieces of glass have been cut out in an oval,...
square, hexagon, octogon, or other suitable shape, they are put in a sort of
ruling apparatus formed of two series of rules, arranged in two parallel planes,.
the rules of the upper planes being situated in a perpendicular. direction to
those of the lower plane. Over the middle of its width each rule has a longi-
tudinal slit, through which the point of a diamond may be passed; the glasses
are placed between the two series of rules, and duly maintained in position in
such manner that by impressing with the diamond point on the glasses through;
the said slits, the lines thus marked on the glasses will indicate the middle of..
say,

page_text: each of the two surfaces of each of them, so as to allow of, after having one.
surface of the glasses ground to the proper shape, in the manner as will be
described hereafter, they may be reversed in order to be ground.on the other
side or surface, for which purpose they are taken off from their resting plates
on the prism S, and cemented again thereon with the opposite side or surface
uppermost, observing thereby to put the central or middle line marked on this
surface at right angle with the direction in which the central line of the
opposite surface was situated during the grinding of that surface; these two
central lines laying in two parallel planes their directions will cross each other
at right angles, and as they serve as guides for the fixing of the glasses on the
sides of the prism S the direction of the curvatures of one surface of each
glass will cross the direction of the opposite surface at a right angle also.
The glasses fixed on the prism having thus been sufficiently ground down and
polished on one surface, they are taken off and fixed again to the prism in the
manner as has just been explained, in order. to have their opposite surfaces
ground down and polished; and in this manner we obtain glasses offering on
both sides a cylindrical surface, but with the direction of their directrixes
laying at right angles to each other. In order to permit of fixing the glasses
on the plates by means of any suitable cement, a small frame of the size of
these plates is placed round them; this frame is of sufficient depth, that after
the molten cement has been poured in it, to allow having the glass properly
fixed at the required height; the cement having become sufficiently hard the
said frame is removed, and the glasses will thus remain fixed on the plates on
the surfaces or sides of the prism S. The mode of acting of this machine will
be easily understood; the glasses to which we wish to give the required
cylindrical surfaces in the manner as has been explained being cemented to
the sides T of the prism S; this prism is laid with the trunnions of its shaft J
in the bearings O, and the remainder J¹ of this shaft is connected thereto
by means of the boss R; this shaft J¹ being provided also, with suitable trun-
nions for turning in proper bearings or plumber blocks. This part, J' remains
laying in its bearings, whereas the prism S, with its shaft J., is removed when
required and replaced by another prism; sand, or other suitable grinding
material having been put in the cup. N, the shaft J is put in gear by the
friction clutch P¹, and the motion of the prime mover will be transmitted to
this shaft J, in consequence of which the prism S will begin to revolve. The
cone pulleys P transmit the revolving motion of the prime mover to the shaft
J, to the end of which are keyed the fly wheels M, to which latter the rods L
are connected by means of the crank pins M', which rods L will thus receive
a reciprocating or to-and-fro motion, and transmit this motion to the casing or

page_text: carriage B, and consequently to the cup N fixed to this carriage B. This cup
N will thus require only to be lifted up till the sand or other grinding material
with which the same is provided comes in close contact with the glasses on
the prism S; this elevating or lowering of the cup takes place by means of
the hand-wheel G', which causes the screw C, and consequently the cup N,
to rise, so as to bring this latter and the sand or other grinding material con-
tained therein in contact with the glasses, and consequently by causing this
cup N to rise gradually during the operation, in the same measure as the
surface of the glasses become ground off, these latter having finally got the
rough cylindrical shape by means of sand, they are then ground or frictioned
with emery, bloodstone, or other fine materials, and finally receive the polish;
the machine is then stopped, the prism S removed and replaced by a fresh
one, with which the same series of operations take place. The glasses of the
first prism are taken off from the cement and fixed again on the prism in the
manner as has been explained above, in order to have their opposite surface
ground and polished in the same manner as has been said for the first surface.
It will be understood that the radius of the cup N, the number and the size
of the sides of the prism S, the speed of the machine, and its various parts
and its general dimensions must be regulated according to the curvatures and
sizes of the glasses, and in general to the work to be performed. As the
concavity of the cup N might, after a certain length of time, become more or
less altered, it is necessary to have a ready means of restoring this curvature,
for which it will be only required to apply on the sides T of the prism S,
instead of the plates, segmental pieces of cast iron, and which thus transform
the surface of the prism S into a cylinder, by means of which the cup N may
then be ground out to the required concave form. We may in the same
manner diminish or augment the number of the sides of the prism by applying
to its surface suitable plates, and thus, for instance, transform a twelve-sided
prism into a six-sided one, or a six-sided into a three-sided; or on the
contrary, transform, for instance, a four-sided prism into, an eight-sided, this
again into, a sixteen-sided, and so on.
For producing divergent cylindrical lenses, instead of applying the glasses
on the prism S, these latter are fixed on the contrary in the cup N, in which
case the prism is replaced by a grinding cylinder, which latter is finally
replaced by a polishing cylinder; the diameter of these cylinders depending
on the degree of curvature to be given to the lenses in such manner that the
number of cylinders and of cups with which the machine is to be provided
depends on the various degrees of curvature which are wished to be given.
For preventing that the reciprocating motion of the casing or carriage should

page_text: get out of order by the removal of the sand, emery, or other materials that are
employed for the grinding or polishing glass plates enclosed in proper frames
turning on hinges, enclose the cup. N, and proper outlets are made on the
sides of this latter for allowing the turning off of the said materials.
A modification of this machine is represented by the Figs. 6, 7, 8, and
9, of Sheet. III., which modified machine is arranged in such manner as
to allow of giving to the surfaces of the lenses any required curvature.
Fig. 6 represents a front, and Fig. 7 a side elevation of the machine ;-
Fig. 8 represents a top, and Fig. 9. an elevation view. of. a modification
of the grinding parts. In these Figs. 6, 7, 8, and 9, corresponding parts
are indicated by the same letters of reference.. The machine consists of a
solid frame, fixed on a strong foundation plate A; the frame is formed of.
two pairs of cylindirical standards A³, each pair supporting two cast-iron
checks A2, whereas a table B, the under side of which is provided with
proper diagonal strengthening ribs B¹,-glides vertically between these
standards. A', by means of the boss B encircling each standard, these
latter serving as guides for the table B, the position of which latter is
regulated by means of the screw C turning in a nut C¹, fixed in the centre
of the table B, a hand wheel C" actuating the screw C. A suitable up-
and-down motion may be imparted to the table B by means of a bell-crank
lever D, one arm of which is situated just below the lower end of the blank
part of the screw C. This lever has its fulcrum in d, and receives an alternate
motion from a cam or excentric E fixed on the shaft of a spur wheel E¹,
driven by another spur wheel E", on the shaft of which latter is keyed a
crank arm F, connected by a crank pin F" to the beam F, the other end of
which latter. is jointed to a carriage G, gliding over the bevilled or dove-
tailed bed plate or table B. On the upper part of the carriage G is fixed
a cast-iron cup H, for containing the sand or other grinding or polishing
materials; the cup I has cast to it a projecting part H', forming boss or
bearing for a small shaft I; to one end of which latter is fixed a grinding.
roller or grinding disc J, whereas to the opposite end a pinion K is fixed
gearing into a toothed rack L, solidly fixed to the table B. The result of
this arrangement will be that the motion of the carriage G will impart at
the same time a revolving motion to the shaft I, and consequently to the
grinding disc J.
A strong cast-iron plate M, fixed to the lower ends of
the two vertical rods M', serves for receiving the glasses to be ground off,
which latter are cemented to the lower surface of the plate M. The two
rods M are kept in a parallel situation to each other by means of the
cross bars or stays M", and the said rods are allowed to glide in suitable

page_text: bosses in an upper cross beam O, where they may be fixed by means of proper
thumbscrews. The cross beam O thus serves as the axis of oscillation for the
swinging or see-saw motion of the balance or pendulum formed by the two
rods M', M', and the plate M. The trunnions O¹ of the cross beam Ọ. rest in
bearings situated in the slides P, which latter glide in vertical slits. P¹, formed
in the cast-iron cheeks A", so as to allow of fixing them at any required
height by means of proper set screws Q, and thus elevating or lowering the
centre of oscillation. The pendulum is moved by means of the rod R, the
other end of which is connected to the pin of the crank R', receiving motion
from the prime mover by any suitable gearing. It will be understood that by
this arrangement the grinding disc J, while revolving on its axis, will partici-
pate also of the alternate up-and-down motion imparted to the table B by
means of the lever arm D, and the excentric or cam.E, and also of the
horizontal alternate reciprocating motion of the table B. The result of these
combined motions, which may be varied at pleasure, will consequently be the
curvature to be given to the glass; in the meanwhile, as the surface of the
glass becomes ground off, it will be required to bring the grinding disc J
closer to this surface, which is done, by means of the hand wheel C". One
surface of the glass having thus been ground to the required form, the glass
is taken off, and cemented by this finished surface to the plate M, after which
the opposite surface of the glass is ground in the same manner. The Fig. 8
represents a plan view, and Fig. 9 an elevation view, of a modification of that
part of the machine, by which the motion is transmitted to the grinding
disc J. In the arrangement represented in Figs. 6 and 7, this disc J was
firmly connected to the carriage G; in the present arrangement two curved
iron guide rails S (the curvature of which corresponds with the curvature to
be given to the lens) are screwed solidly to the table B; on these rails two
grooved pulleys T, connected by an axle U, are caused to move to and fro; to
the middle of this axle U is fixed the grinding disc J, parallel to the pulleys T;
the axle U receives a reciprocating or to-and-fro motion by means of a forked
rod U¹, corresponding with the rod F¹ of Fig. 7, and a small box V is sus-
pended by means of suitable hooks to the axle U below the grinding disc J,
and serves for containing the sand, emery, or other grinding or polishing
materials, which the disc takes up from the box while revolving. In this
arrangement the lever D, and the excentric E of Figs. 7 and 8, are done
away with, the hand wheel C" serving for carrying the disc J more or less
close to the glass, which latter is fixed to the pendulum in the same manner
as in the arrangement of Figs. 6 and 7. It will be understood that this
pendulum arrangement might be employed in combination with a grinding

page_text: cup, as in the arrangement of Figs. 1, 2, 3, and 4, when either large cylin-
drical objectives or small lenses of a very convex form, such, for instance, as
those required for microscopes, are to be manufactured.
The mechanical arrangements above described allow the manufacture also
of lenses of a square or other form for telescopes, microscopes, daguerreotypes,
magic lanterns, and other instruments in which lenses are required.
Having now described the nature of our Invention, and the manner in
which the same is or may be used or carried into effect, we would observe,
in conclusion, that we do not confine or restrict ourselves to the precise details
or arrangements which we have had occasion to describe or refer to, as many
variations may be made therefrom without deviating from the principles or
main features of the said Invention; but what we claim as our Invention
is, the manufacture by mechanical means, and more particularly by those
here above described, of lenses offering on one or on both sides a convex or
concave, cylindrical, or any other curved surface, corresponding in all its
points to the surface formed by the revolution of a given generatrix.
In witness whereof, I, the said Henry Emile Bour, have hereunto set
my hand and seal, the Twelfth day of December, in the year of
our Lord One thousand eight hundred and fifty-seven.
Witness,
J. SOUTH.
H. E. BOUR. (L.S.)