CERTAIN IMPROVEMENTS IN THE MANUFACTURE OF GLASS, AND IN APPARATUS CONNECTED THEREWITH
Year: 1849

page_text: HINRY
TO ALL TO WHOM THESE PRESENTS SHALL COME, I,
BESSEMER, of Baxter House, Old Saint Pancras Road, in the County of
Middlesex, Engineer, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Thirty-first day of
January, One thousand eight hundred and forty-nine, in the twelfth
year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Henry Bessemer, my exors, admors, and assigns, Her especial
licence, fall power, sole privilege and authority, that I, the said Henry
Bessemer, my exors, admors, and assigns, and such others as I, the said
Henry Bessemer, 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, aud
vend, within England, Wales, and the Town of Berwick-upon-Tweed, my
Invention of "CERTAIN IMPROVEMENTS IN THE MANUFACTURE OF GLASS, AND IN
APPARATUS CONNECTED THEREWITH;" in which said Letters Patent is contained
aproviso that I,the said Henry Bessemer, should cause a particular description
of the nature of my said Invention, by an instrument in writing under my
hand and seal, to be inrolled in Her said Majesty's High Court of Chancery
within six calendar mouths next and immédiately after the date of the said
...[Price 8d.].....

page_text: 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
Henry Bessemer, dohereby declare that the nature of my said Invention, and
in what manner the same is to be performed, are fully described and ascer-
tained in and by the present Specification thereof, reference being had to
the Drawings hereunto annexed, that is to say :-
Whereas the ordinary casting table consists generally of a large plate of
cast iron, from twelve to fifteen feet in length, five to seven feet in width
and from four to six inches in thickness, more or less, which is placed either
on a bed of masonry, or on a frame with wheels, and is planed to a true level
on the upper or casting surface. And whereas in order to cast plates of glass
perfectly flat, and of one uniform thickness, it is necessary that the table should
maintain throughout the operation of successive castings the-same true plane
as at first, but this is prevented by the unequal expansion of the iron, for a
soon as the liquid glass is poured upon it the upper surface of the thick table
absorbs heat therefrom, and becomes expanded more than the under surfaces
producing thereby a slight curvature of the table, which curvature becomes
greater and greater with the addition of each successive potful of glass.
Again, the ordinary casting table is placed in a horizontal position, and the
plate of cast or rolled glass has to be removed from it while in a soft state,
and the force required to slide it off the table renders it necessary that the end
of the plate should be folded up,and a sort of peel or pusher placed within the
folded portion, by which means the soft plate is made to move in the required
direction, the folded portion going foremost. Although this causes a waste of
the folded part it is rendered necessary by reason of the weight of the plate
being too great to be pushed from behind edgewise on a horizontal plane with-
out putting it out of shape. Moreover, in the ordinary mode of casting on a
table, the large roller which is passed over the glass to form it into a plate is
either allowed to fall down on a trestle when it arrives at the end of the table,
or is removed on a frame with wheels, in either of which cases an interval is
left between the end of the casting table and the mouth of the annealing kiln
equal to the diameter of the roller, which interval has to be filled up by a
boarded or other surface, over which the soft glass is pushed into the oven, or
the plate of glass is put on to a wooden truck and wheeled by the workman
to the mouth of the annealing kiln. And whereas, also, kilns have for a long
time been in use for annealing plate or east glass, having the bottom or floor
formed with fire tiles laid on sand, and it is frequently necessary to employ a
workman to get into the kilus to readjust the tiles. Nevertheless the general

page_text: surface they present is neither flat nor uniform, and as the soft sheet of glass
takes an impress of the irregular surface on which it is laid, it thereby
requires much more grinding before it can be reduced to a true plane, besides
which it has to be made much thicker than is ultimately required in order to
compensate for the loss iu grinding. The arched roof or crown of sucb kilns
is generally very thick, and covered over with sand or other bad conductor of
heat, the consequence of which is that they cool very slowly, that several days
are ordinarily occupied in the annealing process,and that a great many more
kilns are necessary than would be required if the kilns were cooled down more
quickly. In the ordinary kilns, too, the heat is derived from one or more
furnaces in immediate connection therewith, and a flue or flues leading there-
from. By this mode of heating it is not possible to get an equal temperature
at all parts of the kiln, since those parts nearest the furnaces will receive much
more heat than the more distant ones, and when the kilu is closed currents
of air are sure to traverse the kiln and flues unless all the inlets and outlets
are made absolutely air-tight, which currents must have the effect of causing
an unequal cooling of the plates of glass within them. Farther, as the flame
plays through the kiln, soot and dust or fire ashes will accumulate therein and
add to the inequalities of the floor arising from the other causes aforesaid.
Now my said invented improvements have for their object to remedy these
and other defects in the manufacture of glass as now carried on, and are as
follows:-
011
Firstly, I construct and use the casting table in the manner represented in
Figures 1 and 2, Sheet A, of the Drawings hereunto annexed, Figure 1 being
a side elevation and Figure 2 an end elevation of the table. The frame
consists of two side pieces a, a, connected together by two end pieces b,and is
mounted on wheels c, c, keyed on the axle d, which work in bearings e, e, cast
upon the frame. The wheels are for the purpose of allowing it to be easily
removed from place to place when required. The table or surface f, f.c
which the glass is cast or rolled,may be of the dimensions generally used, but
instead of being fixed permanently in a horizontal position it is supported on
trunnion pins g, g, which rest in hollows formed at a* in the side pieces. i, i,
are pins secured to a chain, which pins pass through the side piece a, and
into holes made in the edge of the table to receive them. Both surfaces of the
table f, f, are to be planed true and level. The roller and guides, as well as
the "tangs" or bars for determining the thickness of the plate, may be made
and used in the ordinary way. When it is desired to cast or roll the contents
of several pots of glass, the pinsi, i, are inserted through the frame in order to
keep the table steady. The casting may then be proceeded with, and as soon

page_text: as the plate of glass is removed from the top surface of the table the pins i, i,
are to be withdrawn, and the table moved upon its trunnions until the
under surface becomes uppermost, when the pins i, i, are again to be inserted,
and the casting of another plate of glass proceeded with. As soon as the
second potful of melted glass is poured on to the table, the expansion of
the surface in contact with the glass tends to neutralize the warping caused
by the former operation, and by the amount of expansion being equalized on
both sides, not only is the flatness of the table preserved, but its liability to
crack is greatly diminished. In continuing the casting operation, the two
sides of the table are to be used in regular succession. A hollow place must
be made in the floor beneath the table in order to allow it to turn round. The
dotted lines shew the position which the table will assume at a particular
part of a revolution on its trunnions.
Secondly, my Invention consists in mounting such casting tables as are
intended to be used on one side only in such bearings and in such manner
that the plates of glass may be moved from them at once into the kiln or oven,
without having to pass over any intermediate surface, and without requiring
the end of the plate to be folded up as heretofore. Figure 3 (Sheet A) is a
side elevation of a table so constructed. Figure 4, an end elevation, with part
of the framing n and same other pieces left out, for the sake of shewing the
other parts more clearly; and Figure 5 is a longitudinal section taken through
the centre of this apparatus. The framing of the table consists of two side
picces, m, which are secured by cross pieces n, N. The table o, which is in
this case formed of a large plate of iron planed flat on its upper surface, is
supported on trunnion pins p,p, which project from each side of it,and rest in
hollows me, formed in the side pieces. On the under side of the table there
are two levers 7, 7, which move in joint pieces s, s, which are secured by bolts
to the table. On the lower edge of the side frames there re projections 9,9,
into which the wayshaft t works at both ends. Levers ", u, are keyed at
their lower ends on to the wayshaft t, and the upper end, which is forked, is
jointed to the levers 7, 1. When these levers 7, 1, and u, u, are both in a
vertical line, as represented in Figure 3, they form a support for the table.
In order to change the horizontal position of the table, as shewn in Figure 3,
to the inclined position shewn in Figure 5, it is necessary to cause the levers
and to deviate from the vertical line, and for this purpose another lever w
is keyed on to the centre of the shaft t, to which lever is attached by a joint
the connecting rod a, the other end of which is jointed to the bent lever y,
which moves on a joint made in the angular piece of iron z, which is bolted to
the table. To give the table the inclination shown in Figure 5, the handle y❤

page_text: is to be pulled upwards, and its bent end acting on the rod a, will cause the
levers n, u, and w, to move on their axis t, carrying with them the lower ends
of the levers r, r, and thereby causing the end of the table o✶ to sink down
until it rests on the ends of the adjusting screws A, A, one end of which
passes through projections B, cast on both the side pieces m, m. C, C,
represent a section of a portion of the floor of an annealing kiln, having a
large block of stone or fire lump D partly projecting outwards from the mouth
of the oven. E is the roof, and F the frout wall, which is supported by a
large plate or girder of iron G, with a flange at G*, which extends entirely
across the oven, and rests on the side walls. At the lower side of this girder
G there is a narrow flap or door Q, which extends across the oven, and closes
the wide opening through which the plate of glass is pushed into the oven.
The girder G has two iron brackets H. securely bolted to it, and of such height
above the table that the long projecting axis I, I, of the roller J may pass on
to and rest upon these brackets. When the roller is moved to the end of the
table o*, the casting table is brought into its required place in front of the
annealing oven by moving on flanged wheels K, K, which run on two lines of
sunk rails L, L. These wheels are supported in iron frames N, N, which
extend across the lower rail of the framing, and are bolted to the side pieces m.
When the operation of casting is to be performed, the table is wheeled to the
front of the oven in which the plate is to be annealed, and the screws M, M,
which pass through projections P, P, formed on the side frames m,are turned,
so as to give a firm support to that end of the table. The roller used to form
the plate of glass is then put on the table, and made to rest on bars of iron at
each side, by which the thickness of the plate of glass is to be regulated. The
modes of preventing the spreading of the glass laterally,as also of pouring the
glass and moving the roller over it, are similar to those in ordinary use in the
casting of plate glass, and need not therefore be here described. In Figure3I
have shewn the roller advancing towards the annealing oven, leaving behindita
sheet of glass R, and in front of it a portion of the soft mass R*.
By the
further advance of the roller the soft mass will be flattened out,and as soon as
the roller has advanced so far that its axis passes on to the brackets H, H
the handle y must be lifted, and the table thus made to assume the
position shewn in Figure 5, whereupon the roller R will be left upheld by its
axis on the brackets H, H, as shewn in Figure 5. The sheet of glass will
then be pushed into the oven, the force required to do which will not injure
the still soft plate, because the inclination of the table and oven is such that a
very slight push from the end furthest from the oven will cause it to slide
freely. As soon as the plate is within the oven, the flap Q must be shut

page_text: down, and the table brought again into the horizontal position by the
depression of the handle y*. The table in rising will come in contact with
the under side of the suspended roller, and lift it off the brackets H, H. The
roller may then be moved along the table to the opposite end, to be in readiness
for a repetition of the casting process. The heating of the oven and the
levelling of the bottom of it may be effected in the manneratpresent practised,
and all that is needful to adapt the oven to the improved process of casting
just described is to make the floor of it incline to the same angle as the table.
In
cast is made in various pieces, all
These pieces may be of cast iron,
Thirdly, my Invention consists in constructing tables for casting glass of a
number of separate and detached pieces made fast to one bed plate. Figure6,
Sheet A, is a side elevation, Figure 7 a longitudinal section on the line A, B,
of Figure S, and Figure S is a sectional plan of a table on this plan with some
of the parts removed in order that the others may be more clearly exhibited,
Figures 9, 10, 11, are portions of the apparatus on a larger scale.
Figure 6 the side frames 1, 1, have brackets formed on them at each end at 1*
in order to support the rollor 2 during the inclination of the table, and hereby
to dispense with the brackets in front of each oven. This arrangement con-
stitutes the only difference between the framing of this apparatus and that
represented in Figures 3, 4, and 5, and as the raising and lowering of the
table may be performed in precisely the same manner, I have not shewn in
Figure 6 the levers necessary for that operation In this modification, how-
ever, the surface upon which the glass is
of which are bolted on to a bed plate 3.
and either cast with the head of a wrought-iron bolt imbedded in them, as
shewn in Figure 9, or with a bent or staple piece, as shewn in Fig.re 11.
The block 4, Figure 9, consists of a piece of cast iron, of about six inches
square on its upper surface, and one and a half inch thick, and has a stout
iron bolt 5 and nut 6 projecting from the under side of it. There is also a
square piece 7 of baked pottery ware, fire stone, slate, or other bad conductor
of heat, placed upon the bolt and in contact with the iron block 4; this piece
of pottery ware or other material is shewn in plan in Figure 10. Figure 11
differs only in having two bolts projecting from and being thereby more
securely fastened to the table. As many of the blocks 4 as are required to
cover the surface of the casting table are to be made very flat and of equal
size, and the bolts being put through the holes 8 in the table, a small quantity
of what is known as "iron or rust" cement is to be put between the surfaces
of the block 4 and the piece of pottery ware 7, and also between the piece of
pottery ware 7 and the table 3. The nut 6 is then to be put on and the
whole firmly screwed to the bed 4. In like manner all the other blocks are to

page_text: be put down, care being taken to make them level with each other, and to lay
them in such a position as to "break joint," as represented at 4,4,4, Figure S.
These blocks are also to be placed near although not quite close to each other,
so that a minute interval is left all around each block. The upper surface
must now be rendered perfectly smooth and flat by grinding, which will be
best done by placing it on one of the machines used for grinding plate glass,
using a large slab of planed iron to move over it with water and emery. The
table having thus been brought to a perfectly true and level surface, is to be
mounted on trunnions, as represented in Figure 6. As soon as a potful of
melted glass is poured upon a table constructed in this manner those blocks
on which the glass falls will begin immediately to expand by the absorption
of heat, but as there is a minute interval between each block this expansion
may take place without producing any curvature in the general surface; nor
will the bed plate 3 become strained or warped thereby, because the piece of
pottery or slate will obstruct the transmission of heat to it; but if extreme
accuracy in the surface of the table is required, it will be better to keep
the bed 3 cool by passing cold water through passages formed in the interior of
it; these passages are shewn most clearly in Figure S, where 9, 9, represents
a continuous passage formed by connecting the alternate ends of a number of
passages cored in the metal. When this means of couling the bed plate is
adopted, the entrance pipe for the cold water at one end of the table should
have a piece of elastic pipe attached to it, in order that it may follow the
movements of the table, and the same provision must be made for the exit
of the warm water at the opposite end of the table. The surface of the casting
table being divided as I have described by narrow sunk lines, a slight indi-
cution of these lines may be visible upon the sheet of glass, but this will
not interfere in any way with the general level of the sheet.
Fourthly, the advantage of a more equal thickness in the different parts of a
sheet of cast glass, resulting from the prevention of warping of the table by
forming its surface of a number of detached pieces, may also be obtained by
placing a number of pieces of iron or gun metal upon a table, and jointing
them so as to form a chain stretching across the whole width of the table, and
extending not only over the entire length of it, but over polygonal drums
at each end, thence it returns under the table, forming in effect an endless
band or chain. These blocks or pieces of metal forming the chain must be
made flat and parallel on those sides which come in contact with each other,
and the upper surface of each block must be at right angles with the sides
and parallel with the under surface. At one end of the block there project
two semicircular lugs with a space between them, and at the opposite end of

page_text: the block there is one projecting lug in the centre of a thickness equal to
the space between the other two. Round holes are made in the centre of
the lugs, so that when any number of them are placed so that the single lug
of one block is inserted between the double lug of another block, and a pin
passed through the hole, a joint will be formed similar to the joints used
in a carpenter's rule. It will be readily understood, that if the joint pins
are long enough, any width of chain may be formed by putting on the blocks
in parallel rows. Care must be taken to arrange the blocks so as to be flat
and even on the upper surface.
The apparatus used for forming plates or sheets of glass with the endless
chain, first described, is represented in Sheet B of the Drawings hereunto
annexed.
Figure 1 is a vertical section taken through the centre of the machine;
Figure 2 is a side elevation; and Figure 3 is an end elevation. A, A, are
two side pieces of cast iron connected together by the end pieces B, B. Cis
a stout bed or table of cast iron planed flat on its upper surface; it extends
across the whole width of the apparatus, and is held firmly in its place by the
lugs D, through which the bolts E pass, and secure it to the side pieces of the
frame. F, F, are brasses which are let into the side pieces B, and form the
bearings in which the axis G of the polygonal drun H revclves. These
brasses are tightened by a wedge or key I. At the opposite end of the machine
there is another polygonal drum J keyed on a shaft K, which shaft also turns
in brasses precisely similar to the brasses F, F. L, L, is the endless chain,
which passes over the polygonal drums H and J,and bears also on the table C.
The side pieces A of the frame have a part projecting upwards at A*, the top
part of which is slotted and fitted with a sliding brass M. through which passes
the wayshaft N, which extends through the brasses and has a radius bar P
keyed to one end of it, and another radius bar Q keyed to the other end.
The opposite ends of the radius bars are bushed with brass, and have a shaft R
passing through and rovolving in them. The shaft R has on the central
portion of it a large hollow cast-iron roller S, precisely similar to the rollers
now used for casting glass. At one end of the shaft R there is keyed a
drum T, and at the other end of it a similar drum U. These drums T and U
rest on the peripheries of two other drums V and W, which are keyed on the
axis K. of the polygonal dru n J. By this means the roller S is prevented
from bearing upon the chain, its distance above which is regulated by the
screws X, X, of which there is one on each side of the framework. These
screws when turned round in one direction move the wayshaft N and radius
bars P and Q, and also the roller S and drums T and U, nearer to a vertical

page_text: position above the polygonal drum J, and consequently elevate the roller S
further above the chain, and thereby put the machine into the condition to
produce a thicker plate of glass. The thickness will depend on the distance
between the upper side of the chain and the under side of the roller. If
the screws X, X, are turned in a contrary direction to that described, the
roller will come nearer to the chain, and a diminution of the thickness of
the plate will result therefrom. Y is a sort of hopper, into which the fluid
glass is to be poured, or if the hopper is dispensed with, two guides, similar to
those at present used in casting plate glass, may be employed to prevent the
liquid glass from spreading laterally. Motion may be transmitted to the
inachine from any first mover put in connection with the clutch Z, which is
keyed on to the polygonal drum shaft K. The revolving motion of this shaft
will cause the chain to slide beneath the roller S, and along the surface of the
table C, and the pressing roller will receive motion by the pressure of its
drums T and U on the drums V and W, consequently, if fluid glass be poured
into the hopper Y, as shewn at a, Figure 1, it will be rolled out into a sheet, as
seen at b, and as the end of it approaches the thin edge of the table c, it will be
guided on to it, and as the motion of the chain is continuous, a sheet of glass
will continue to be formed so long as there remains any in the hopper, the
length of the table in this case not limiting the length of the sheet of glass.
The sheet of glass thus formed may be passed at once, whole, into the
annealing oven, or it may be cut into any desired lengths by the means
already known and practised for that purpose. The table and chain may,
instead of being placed in a horizontal position, as here represented, be made
to incline to any convenient angle, in order to facilitate the sliding of the
sheet of glass, and also the drums T, U, V, and W, may, if thought desirable,
be furnished with small and well divided teeth to prevent the possibility
of slipping; but I prefer the plain drum, as here represented.
Fifthly, my Invention consists of an improved mode of constructing,
arranging, and adjusting the various parts which form the surfaces or beds
on which glass is annealed, or on which it may be placed, while in a soft
state, after casting or rolling. This improved mode is represented in
Figures 4, 5, 6, 7, 8, Sheet B, of the Drawings hereunto annexed.
Figure 4 is a vertical cross section of the kiln on the line A, B, of Figure 6,
shewing within it an end elevation of the annealing bed; Figure 5 is a front
elevation; Figure 6 a horizontal section taken on the line 0, 1), of Figure 7,
and shewing within it a plan of the annealing bed; Figure 7 is a longitu-
dinal section of the line E, F, of Figure 6; and Figure 8 is & plan of a portion
of the annealing bed. 1 is a shallow rectangular cast-iron box or chest,

page_text: strengthened on the sides and bottom by ribs 1*; it is supported on flanged
wheels 2, keyed on the axles 3, which work in proper bearings formed in the
brackets 4, which are bolted to the rib 1. A number of oblong blocks 5, 5:
of burnt fire clay, fire stone, or other suitable material (I prefer the material
used for making glass pots), are ground true on the four sides thereof and the
ends carefully ground at right angles to the sides. The blocks are placed
on end within the box 1, in regular rows, each row breaking joint with
the other, as shewn in Figure 8. In the bottom of the rectangular box 1
there are screws 6, 6, so arranged that the centre of each block may rest on
the end of one of these screws, in order to bring the upper ends of the
blocks 5, 5, to a true level with each other. The screws 6, 6, may be turned
so as to raise or lower each block, by which means a very accurate surface
may be obtained, and from the closeness with which they approach each other,
only very slight marks will be left upon the glass. Whenever repairs arerequired,
he whole bed may be moved on its wheels out of the kiln, and any defective
block removed and re-ground on the upper end, or it may be replaced by a new
one. In the front of the kiln there is a pair of iron doors (7) for the purpose
of allowing the annealing bed to be removed. The upper parts of these doors
have a fire-lump 7* fitted into them for better retaining the heat.
Sixthly, my Invention consists in constructing the annealing ovens with
double crowns and sides, whereby a more equable degree of heat is maintained
therein. Those portions of the blocks 5, 5, which project from the upper part
of the box 1 fit nearly close to a projecting part 8 of the side walls 8 of the
kiln, and thus divide it into two chambers, which prevents the heat in the
upper one from injuring the ironwork of the box 1, which is the lower part.
The arched roofed or crown of the kiln 9 I prefer to make only half a brick in
thickness; it is separated by an interval 10 from the outer crown 11. At the
level of the floor there is an arched opening 12, which extends within the
thickness of the wall all along both sides and the end of the kiln. This
opening or passage has a number of vertical openings 13 communicating with
the
space 10. The position of these passages (13) are seen best in Figure 6.
On the top of the outer crown 11 there is a square passage 14 running
horizontally the whole length of the kiln, and terminating in an upright
passage or flue 14*, which should extend upwards for several feet in order to
produce a draught. The lower part of the passage 14 has an iron plate 15
bedded in it, which has a number of square openings 16 in it, which are directly
over the openings 17, which pass through the upper crown 11 and communicate
with the space 10. Another iron plate or slide 18 has openings similar to
those in the plate 15. The end of this slide has a part 18* projecting upwards,

page_text: through which the screw 20 works, which screw is supported in two projections
15, cast on the plate 15, and is prevented from moving endwise by the
collars 21 formed on the screw shaft. Motion is given to the screw by a
handle 22, by which also the openings in the slide 18 are made either to close
up or open the holes communicating with the space 10. These openings (18)
are to remain closed when the kiln is being heated (by the means hereafter to
be described). The air occupying the space between the two crowns will, by its
being a bad conductor of heat, facilitate the heating of the kiln by checking
the radiation of heat therefrom; and after the required temperature is arrived
at, and the sheet of glass put into the kiln, as represented at Z, Figure 4, the
temperature may be reduced by turning the handle 22 and establishing a com-
munication between the space 10 and the vertical passage or flue 14*. The
heated air previously occupying the space 10 will immediately ascend and
escape by the passage 14*, while fresh portions of cold air will enter the arched
passages 12, and ascending the vertical passages 13 will sweep over and cool
the thin arched roof of the kiln. It will be obvious that the quantity of air
circulating between the two crowns will depend on the extent of the opening
of the slide 18; and in order that the workmen may be enabled to regulatethe
cooling of the kiln so as to effect the annealing properly, I place within the
kiln an apparatus for indicating the temperature of it by the difference of the
expansion of two dissimilar metals. A view of this apparatus is given in
Figure 7. is a steel bar which extends the whole length of the kiln and
rests on the end walls and projects through the front wall, having a joints,
in which a lever or poiutert is fitted. On the under side of the barris another
bar u of copper or other metal, whose rate of expansion by heat differs from
steel. The copper bar is secured by a collar and nut to a projection *** on the
steel bar. The other end of the copper bar, after passing through a guide u*,
rests against the short end of the pointer t, its contact with which is ensured
by the spring o, which presses against the pointer. w is an indicator fastened
to the front of the kiln, on which degrees of heat are to be marked, which
will be equally a guide for the regulation of the temperature, whether such
degrees correspond with the thermometer in general use or are merely
arbitrary numbers understood by the man in charge of the annealing process.
When a sheet of glass is to be put into the kiln, the doors 7 are opened, and
the annealing bed brought forward a short distance on its wheels 2, which
inove on sunk rails, not shewn in the Drawings. The plate is then put upon
the flat surface or bed formed by the upper ends of the blocks 5, the bed
pushed back to its original position, and the doors closed. To form a good
joint with the upper edge of the doors, a small sliding or packing piece 24

page_text: is fitted into a groove in the upper part of the door frame 25; this packing
piece is prevented from falling out by the pins 26, which pass through
slotted holes in it, so that while they admit of a slight movement, they retain
the packing piece within the groove. 27 are the hinges on which the doors 7
move, and 28, knobs for opening them.
Seventhly, my Invention consists of au improved method of heating anneal-
ing ovens or kilns.
Figure 1, Sheet C of the Drawings, is a front elevation, and Figure 2 a
vertical section, through the centre of the apparatus which I use for this
purpose. a is the outer wall of a circular furnace, secured by iron hoops b; C
is the door frame, and d the door by which fuel is supplied; there are also
two spy holes e, ce, for the purpose of ascertaining the state of the interior.
ff, are fire bars. g¹ the chamber in which the fire is made. " is another
chamber of larger diameter immediately above g, in which is placed a coil of
iron pipes h. i is a cylindrical vessel that is suspended above g2 by an upper
flange, and is provided with a cover i*. The bottom and sides of the vessel
are exposed to the action of the heated matters within the furnace. g* is the
entrance to the flue or chimney. The vessel is partly filled with fluid metal,
and the upper part is occupied by a cylindrical plunger or piece of iron j
suspended by the rod j. A little above the surface of the fluid there is a
branch pipe k, communicating between the vessel i and the pipe l, the latter of
which is a continuation of the coil in an upward direction. n is a piece of
pipe in connection with the lowest part of the coil h. The piece n also takes
a vertical direction at n 1, and afterwards a horizontal one at a 2, where, by
means of a double elbow, it communicates with a series of pipes p, having
bends at each end so as to form a lengthened but continuous passage. In the
Drawings this series of pipes is shewn broken off in order to indicate that the
number or length of them may be varied to suit the dimensions or other
requirements of the kiln or chamber in which they are to be placed. The
pipes p, p, finally terminate in the vertical pipe l. 9 is a cock communicating
with a steam pipe, so that by means of the pipe steam may be circulated
through the pipesp, up the vertical branch 7, and down the small pipes, which
extends along the horizontal pipe n 2, and down the vertical pipe n 1, and
finally projects from the lower end of the pipe n at s*. The fire having been
made in the chamber g', and the metal in the vessel i and coil having been
heated to from 500 to 700 Fahrenheit, steam is now admitted through the
cock g, which, after traversing the pipes p, r, s, n 2, and n 1, is discharged
at s. By this means the temperature of the pipes may be brought up to
the point suitable for the introduction of the fluid metal into them, which is

page_text: effected by forcing down the plungerj into the fluid metal. As the surface of
the metal rises it will ascend the pipe 1, and passing through the series of
pipes p, and return pipes n 2 and n 1, will enter the lower part of the coil. The
ascending power of the heated metal in the coil will continue to supply fresh
heated portions of the fluid to the pipes p, while that which has lost part of its
heat, and been thereby increased in specific gravity, will return to supply the
coil 6 and keep up the circulation. The metal which I prefer for this purpose
is a compound of eight parts bismuth, five parts lead, and three parts tin, and
from its being enclosed in pipes out of contact with the air, and not being
volatilizable at high temperatures, a great degree of heat may be thus trans-
mitted without wasting the alloy by oxydization and without risk of explosion
In Figure G, Sheet B, is represented within the annealing kiln a series of
pipes p, which may be supposed to be the same as those represented at p,
in Figure 2, Sheet C, in which case the pipes land n, Figure 6, Sheet B, would
communicate with the upper and lower ends of a coil of pipes, as shewn in
Figure 2, Sheet C, and by the arrangement here explained a circulation of
hot metal may be kept up in the kiln until it acquires a temperature sufficient
for annealing a plate of glass. The circulation of the fluid metal may be kept
up by other means than the difference of its specific gravity at different tempe-
ratures, such as by pumping it or moving a vane within the pipes, &c., as any
convenient means for giving circulation to the fluid will answer equally well.
When it is desired to cool the oven the metal should be withdrawn from the
pipes by raising the plunger j and allowing the metal to occupy its
place; this plunger may be raised by a screw, lever, or other convenient
means, since the particular mode of doing so will not interfere with the
effects thereby produced. The chief reason for withdrawing the metal from
the pipes p is that if they were reduced in temperature below 212, the
metal would become solid within them, and cause great inconvenience. It is
chiefly to avoid this inconvenience that steam is blown through the pipes before
returning the fluid metal into them. When the kiln requires to be fresh
heated, it will be readily understood that such an apparatus as is represented
in Figures 1 and 2, Sheet C, may be in ide to heat several kilus in succession
by employing cocks to turn on or off the communications with the respective
series of heating pipes, so that the heat may be continually kept up in the
apparatus. I wish it to be understood that kilns or ovens for annealing other
descriptions of glass may be heated by the circulation of fluid metal, the quan-
tity, size, and arrangement of the pipes being proportioned to suit the chamber
to be heated. The flat bed or surface for annealing may be also used where
other modes of heating and cooling the kiln are practised; and in those cases
where these annealing beds are to be used in connexion with the modes herein-

page_text: before described of casting on a horizontal table, and then tilting the table to
facilitate the removal of the sheet of glass into the kiln, it will be neces-
sary to construct the annealing bed lower at one end than at the other to
suit the angle to which the table is moved. If the system of heating by
the circulation of hot metal in pipes be used, then the pipes should also lie
in an inclined position, so that they will be all of an equal distance above
the annealing bed.
In Figures 3 and 4, Sheet (, I have also shewn another apparatus for
annealing by the use of fluid metal, which is chiefly applicable to the annealing
of long glass tubes. It consists of a large cast-iron cylindrical vessel t, with
flanges at each end, to which are bolted the covers u, which have holes in them
in which are rivetted the iron tubes », in a similar manner to that in which the
tubes are connected to the fire and smoke box in locomotive engines. Figure 3
is an elevation of the vessel with a portion left out, in order to shew the
tubes vin section. Figure 4 shews in elevation the end or cover u, with the
openings v. The large vesseltis to be set in brickwork or otherwise covered
by some bad conductor of heat. The pipes wand a are made to communicate
with a heated coil of pipes, as represented in Figures 1 and 2, Sheet C,
and the space between the tubes u being also filled with fluid metal, as soon
us the glass tubes are made they are put into one of the tubes v, and when
it is filled a small stopper or plug of clay is inserted into the end of the
tube v, and so on until the whole are filled, when the apparatus may be left
to cool slowly.
Eighthly, my Invention consists of an improved arrangement or disposition
of the kilns or ovens with reference to one another, and to the position of the
melting furnace. When plates or sheets of glass, are made rapidly by any
inachinery, or when a large plate is divided into several smaller ones while
hot, there is some difficulty in removing them sufficiently quick to the
annealing kiln in which they are to be deposited, more particularly when such
kilns are at a great distance. I therefore construct a kiln or oven within a
suitable framing of iron, and by mounting the same on flanged wheels, it may
be brought on rails to the spot where it may be required, the plates be
deposited therein, and be again moved to some distant part, where it will be
out of the way during the cooling down of the plates or sheets of glass.
Figure 5, Sheet C, is a vertical section of this apparatus, and Figure 6 a front
elevation of it. A is an angle iron frame, which encloses the kiln on all sides,
and has folding doors B in front of it. The whole of the exterior framing,
including the doors, is filled with brickwork C, in order the better to retain the
heat. In the lower part there are four small fire-places or furnaces D, two of
the doors of which are seen at E, in Figure 6 (the other two, which are not

page_text: seen, are at the back). F is a hollow space between the furnaces, the top
of which is covered by a thick fire lump G. The fire chambers are also
covered by a similar fire lump, having two or three rows of holes H in them,
for the purpose of allowing the heat to ascend into the body of the kiln J.
I is an arched roof, which is also provided with holes K, for the products of
combustion to ascend through. The doors B have knobs L, by which they
may be opened, and a handle and catch M to keep them shut. When this
kiln is required for use, a small fire is to be lighted in each of the furnaces.
The heat must be augmented gradually, and when the whole of the interior
presents a dull red appearance, the sliding dampers N, N, are to be pulled
beneath the fire-grate, to prevent all further access of air, and the holes (K)
in the crown are also to be stopped with a plug of burnt clay, and the
joint further secured by a little wet clay. The kiln may then be moved upon
its wheels until it arrives at a convenient place to receive the glass. The
doors Bare then to be opened, and the plates quickly set up on edge, leaning
against the back of the kiln. This mode of setting up the plates on edge
is called piling, and is so well understood as to require no further explanation
here. The doors are to be closed as quickly as possible, and the joints made
tight with clay, when the whole may be removed, in order to make room for a
similar operation with another kiln. In works already constructed for the
casting of plate glass, the kilns for annealing it are placed at different
distances from the furnace in which the glass is rendered fit for casting. The
more distant are from one hundred and fifty to two hundred and fifty feet off,
rendering it necessary either to transport the pot of fluid glass a considerable
distance from the furnace to the casting table, or, if the casting table be near
the furnace, then the soft sheet of glass has to be removed to the annealing
kiln after, casting on a wooden truck. Both these modes add much to
the labour of casting, and where the pot has to be carried a considerable
distance, the time occupied in removing it greatly adds to its liability to crack
from change of temperature. To avoid the many disadvantages attending the
great and irregular distance of the annealing kilns from the furnace, and
to render access to all equally easy, I construct the annealing kilns in a circle,
with the glass furnace occupying the centre. The casting table, or other
apparatus to be used in casting or formingsheets of glass,is to be mounted on
wheels,so that it may move on rails in a circular direction around the furnace.
This arrangement will be clearly understood by reference to Figure 3,
Sheet D, which represents a ground plan of a circular building, around
the outside of which the kilus are formed. A, A, are the walls which divide
the kilns from each other; B, B, the kilns; C, C, the spaces left between
1

page_text: them, which are filled with concrete; D, the outer wall, which serves also for
the end wall of the kiln; E, the casting table, supported on flanged wheels,
which run on two concentric rails F and G. The furnace H, in the centre, I
prefer to be constructed on the plan for which I obtained Letters Patent,
dated the Twenty-second of March, One thousand eight hundred and forty-
eight. I is the opening through which the pots are removed. It will be
observed that whenever the crown of the furnace is moved round so as to get
at the pot, the casting apparatus may also be moved upon the rails, and thus
during the casting of any number of pots of glass, the casting apparatus will
present that end to the furnace on which the fluid glass is to be poured,
and at the same time it will present the opposite end close to the mouth of the
kiln, thus affording the greatest facility for its quick removal therein. In
order to carry out this system completely, the kilns should occupy the entire
outer circle, as here represented, in which case access to the circular casting
-hall-can be most conveniently had by steps from the "cave" below. Entering
the hall between the rails, access to the "cave" or lower room will be as
usual, videlicet, by a simple inclined path or roadway leading from without
the building to the lower or underground passages or caves. It will of course
be necessary to place the axles of the wheels which support the casting table
in a position diverging from the centre of the rails, and if the wheels are
keyed on to their respective axles those running on the rail F should be larger
in diameter than those running on the rail G. The proportion which the said
wheelsbear to each other should be in the same ratio as the diameter of the
two rails.
Ninthly, my Invention consists in a new method of constructing flattening
or spreading kilns, and in an improved apparatus for flattening or spreading
cylinders of blown glass. The dust or small particles of ashes which come
over from the furnace are deposited upon the smooth surface of the flattening
stone on which the spreading is effected, and when the glass in a soft state is
pressed upon the flattening stone, small indents are made upon the surface of
the glassby these particles of dust or ashes, whereby the glass is injured and
reduced invalue. When a cylinder of glass is laid upon the flattening stone,
the side that is uppermost is exposed to the intense heat of the flame passing
immediately over it, and is frequently injured thereby; and in the piling
operation, the lifting up of the sheet of glass with a sort of fork from a
horizontal to a vertical position is liable to scratch or indent the glass, and not
unfrequently to bend it. The manner in which I propose to avoid these
injurious effects is represented in Figures 7 and S, Sheet C, and Figures
1 and 2, Sheet D, of the Drawings nereunto annexed. Figure 7, Sheet C,

page_text: is a front elevation of the kiln. Figure S, Sheet C, is a vertical section on
the line A, B, of the horizontal section, Figure 2, Sheet D. Figure 1,
Sheet D, is a vertical section on the line C, D, of the horizontal section
Figure 2, Sheet D; and Figure 2, Sheet D, is a horizontal section on
the lines E, F, of Figure S, Sheet C, and the line G, H, of Figure 1,
Sheet D. a, a, are the outer walls and roof of the kiln. b, b, the bars
on which the fire is made. c, the fire door, and c* the frame of the fire
door. d, the ash pit. e, a retort, fixed on one side of the fireplace, which
is made of fire clay or iron (but by preference of the former), and with-
out a bottom, resembling more a thin arch of fire clay than a retort of the
ordinary construction. At that end of the retort nearest the front of the
kiln it has an open conical mouth e, into which the cylinders are put when
the kiln is in operation. f is a broad flat passage or flue formed between the
top of the retorte and the arched roof a¹ of the kiln, which passage continues
to descend on the side of the retort farthest from the fire until it arrives at the
part of the roof a³, around which the flame and heat will pass and continue
their course up the flue f1, which finally terminates in a vertical flue or
chimney 2. At the end of the retort farthest from the front of the kiln there
is a space f3 left between the end of the retort and the wall a 3 which divides
the kiln. This space is for the purposes of heating the end of the retort, but
to prevent the heat acting too violently on the side of the retort nearest the
fire; the side of the fireplace is carried up in fire clay,as shewn at g, which fire-
clay gradually becomes thinner as it approaches the crown of the retort. A
similar protection is given to the retort at g*. is a chamber having a
cylindrical end i, and a slanting roof, which increases in thickness as it
approaches the flue ƒ 2. The bottom of this chamber is smooth and horizontal,
and has an opening at h* of sufficient size to admit a cylinder of glass. There
is also a circular opening; in the front of the furnace, which communicates
with the chair ber h near its semicylindrical end. k is the flattening stone,
which is supported on a plate of iron n, having ribs n 1 and a strong
central rib n 2, which projects beyond the width of the stone, and has
round axes formed on it, which are supported in bearings llet into the
brickwork of the kiln. Sufficient space is left below the plate n to allow
of its being moved on its axis into the position shewn by dots atk 2. This
movement of the stone k on its axis is effected by depressing the lever or
handle m, which projects through a slot in front of the kiln, and is supported
on a jointed piece o, and connected to one of the ribs n 1 of the plate n by a
short link p. q is an opening extending the whole width of the retort, and
communicating with the large chamber 1, which forms also a portion of the

page_text: 1
kiln. In the lower part of the opening there is a fixed piece of smooth
stone G, or other suitable material, at an angle equal to that which is formed
by the flattening stone. When in the position shewn by dots the chamber
may be heated in the way at present practised in the heating of those
chambers in which the piling of sheet glass is generally effected. Two
brackets s, s, are fastened by bolts to the floor of the chamber r, the over-
hanging ends of which forms a support for the iron plate t, which plate
extends beneath the tilting stone u, and rises on each side thereof at t. On
the raised part there is a joint pin v, so that the tilting stone can move
upwards on this joint until it reaches a vertical position. On the back of the
plate there is bolted a toothed quadrant w, which is in gear with a pinion a
on the shaft y, which shaft is supported in bearings formed in the brackets s,s,
and extends through the outer wall, where it is provided with a handle z.
Within the chamber r I have shewn a moveable annealing kiln A mounted
on wheels A*. This kiln or annealing box may be either of the description
of those already in use for that purpose, or made in the manner represented
in Figures and 6, Sheet C, and which I have herein-before described. The
back of the chamber is provided with doors B, which open on. hiuges C
formed in the door frame D), E is a small rod which passes between the
doors at E, and is hooked to the back of the moveable kiln A. At F there
is a spyhole, through which the workmen may watch the operation of piling.
is a small square plug in the front of the kiln for the purpose of removing
any accumulation of dust or ashes in the lower part of the flue / 4. K, K,
are cylinders of blown glass in the heating chamber h. The action of the
apparatus is as follows:-The fire on the bars b, b, having been gradually
raised till the heat in the interior of the retort is sufficient to soften the
cylinders of glass when put in, and the annealing box or kiln A having been
also brought up to the requisite temperature, a cylinder of glass cut open in
the direction of its length is to be put into the open end of the chamber h.
From the increased thickness of the roof is of the chamber h at the end h*,
and from its greater distance froin the fireplace, as well as from the end being
open, it will be much cooler where the cylinder is put into the chamber h than
it is at j. The gradual movement of the cylinder towards the semi-cylindrical
end i will cause the temperature of it to rise gradually, and as one cylinder
advances others are then put in, and each one is moved to the end in suc-
cession. When opposite the opening j, as shewn in Figure 7, Sheet C, the
heated cylinder is to be removed through the opening, and put into the
retorte, with its cracked or split side uppermost. The heat will then suffi-
ciently soften the glass to allow the cylinder to be spread into a flat plate in the

page_text: manner usually practised. When this is done the handle m is to be pushed
down until the flattening stone assumes the position shewn by dots at K 2.
The workman then pushes the sheet of glass through the opening q on to the
tilting bed u; he next reverses the handle m, and returns the flattening stone
to a horizontal position, and proceeds to flatten another cylinder which has
become heated in the chamber h. As soon as the sheet of glass is pushed on
to the tilting bedu, a workman, watching the operation through the opening F,
turns the handles, and raises the bed a slightly beyond the vertical position,
when the sheet of glass will be deposited against others, as shewn at L, or
against the frames which are sometimes used in annealing boxes. The tilting
bed u is then to be lowered down again in order to receive another plate, but
before this is done it will be necessary to move the box or kiln back a short
distance, which may he accomplished by pulling the rod E which projects
through the doors at E.
Although I have here described the use of the retort of the moveable
flattening stone, and of the tilting bed for piling, as being all combined with
each other, I wish it to be clearly understood that I do not confine my claim
to such combination, as it will be obvious that the retort may easily be adapted
to the present kilns, and the moveable flattening stone and tilting bed for
piling be used without the retort.
Tenthly, my Invention consists in forming the pots used for founding or
refining glass with hollow spaces in the bottom or under sides, in order to lesson
the powerful adhesion of the pois to the seats on which they rest within the
furnace, and also in giving such a form to the lower parts of such pots as will
encrease the facility of holding them by the crane or other apparatus used to
remove them from the furnace.
In Sheet C of the Drawings I have represented some glass pots constructed
according to this part of my Invention. Figure 9 is an elevation and
Figure 10 a vertical section through a cylindrical pot. 1, 1, is a ring which
extends round the pot, but is not of so large a diameter, so that there is a
sort of shoulder or corner 2 left in the body of the pot, which will form a
convenient place for the claws or grips of the crane to hold by. 3 is the
hollow space left beneath the pot; 4, 4, the sides or body of the pot; and 5
the part occupied by the fluid glass. Figure 11 is a plan of the bottom, and
Figure 12 an elevation of another form of pot, in which the ring at the bottom
is of the full diameter of the body of the pot, but is cut into six arched
openings 7, leaving thereby six feet or points of support 8. In this case there is
still less surface to rest upon, while the openings 7 not only serve to admit the
claws of the crane, but allow the heat to circulate beneath the
pot. The
pots represented in Figures 9, 10, 11, and 12 are particularly adapted for

page_text: niting with a crane such as I have described in the Specification of Letters
Patent granted to me on the Twenty-second day of March, One thousand eight
hundred and forty eight, for "Certain Improvements in the Manufacture of
Glass."
Figures 13 and 14, Sheet D, also represent an elevation and section of a
pot, having a hollow space 9 beneath it, but provided with a central boss or
support 10, which may be desirable in very large pots.
Eleventhly and lastly, my Invention consists in an improved mode of tempo-
rarily cementing plates or sheets of glass for the purpose of grinding or
polishing them. When sheets of glass are to be ground flat it is necessary to
hold them firmly upon a suitable bed or frame, and this is generally accom
plished by imbedding them with plaster of Paris. But this material not being
susceptible of a second use without being remanufactured, I employ a substitute
for it, which, by a small addition of heat, may be used again and again for a con-
derable period. I provide for this purpose a wooden frame of the requisite
size, consisting of a number of parallel bars of wood secured by other cross
bars so as to form a strong though light frame, to which bars I attach strips
of gutta percha or compounds thereof. When a plate of glass is removed
from the annealing kiln while it is still warm, and laid upou the strips
of gutta percha, it will adhere to the gutta percha, and may then be placed upon
the machine and ground. As soon as one of the side plate is ground it must
be detached by the same means as are employed to take up the sheets of glass
which are imbedded in plaster of Paris. When one side of the plate is made
flat it may be held down by the pressure of the atmosphere in the manner
described in the Specification of the Letters Patent granted to me on the
Twenty-second day of March, One thousand eight hundred and forty-eight, and
to which I have herein-before referred.
Having now described the nature of my Invention, and in what manner the
same is to be performed, I declare that although I have herein described
several processes, apparatuses, and pieces of machinery which are already to
some extent more or less known and in use, I claim the same only in so far
as regards my improvements therein, which are as follows :-
First, I claim the employment in the manufacture of glass of casting tables,
planed true on both sides, and turning ou trunnions, whereby the two sides
may be used in alternate succession, the one after the other, to cast the plates
of glass upon, as before described.
Second, I claim the mounting of casting tables intended to be used on one
side only, on such bearings and in such manner that they may be raised from
a horizontal position to any angle of inclination that will most facilitate the
removal from them of the plate of glass, when cast, as before described. I

page_text: claim also the mounting of the rollers used in connection with such casting
tables in such manner that when the plate of glass is about to be removed
from the casting table into the annealing oven, the roller passes from off
the glass on to supporting brackets fixed in front of the annealing oven or at
the sides of the table, and is there upheld till its services are again required,
as before described.
Third, I claim the constructing of tables for casting glass of a number of
separate and detached pieces, made fast to one bed plate, as before exemplified
and described.
Fourth, I claim the constructing of tables for casting glass of a number of
separate and detached pieces, connected and arranged in the manner of an
endless chain, and the machinery for working the same, both as before
described; but the latter only in the general combination of parts of which it
consists, and their adaptation to the moving of tables for casting glass.
Fifth, I claim the employment in annealing glass of beds composed of
solid detached blocks, of greater depth or length than width, and adjusted
to an exact level on their upper surfaces by means of screws, one to each
block, operated upon from beneath, and the whole laid in a box or frame-
work mounted on wheels, so that they may be withdrawn at pleasure from
the oven, as before described.
Sixth, I claim the constructing of annealing ovens with a double crown and
sides, as before described.
Seven, I claim the heating of annealing ovens or kilns, by the circulation
through them of heated metal in pipes or chambers, and the apparatus, before
described, for heating the said fluid metal, and supplying or drawing off the
same to or from the pipes within the kiln. I claim also the application of the
said method of heating by means of fluid metal to the annealing of glass tubes,
as before described.
Eighth, I claim the arrangement of annealing ovens in a circle round a
central furnace, having concentric rails, as before described; and I claim also
the construction of kilns mounted on wheels, and containing heating furnaces,
as before described.
Ninth, I claim the improvements in spreading or flattening kilus, before
described, that is to say, in so far as regards the employment of retorts of
fire clay and iron, the method of tilting the flattening stone, and the method of
setting up the sheets of glass.
Tenth, I claim the forming of glass pots with hollow bottoms, and with
shoulders or arched openings beneath, as before described.

page_text: Eleventh, I claim the fastening of sheets of glass to the grinding frames
with gutta percha or compounds thereof, in the manner before described.
In witness whereof, I, the said Henry Bessemer, have hereunto set my
hand and seal, this Twenty-first day of July, in the year of our
Lord One thousand eight hundred and forty-nine.
Enrolled the Thirty-first day of July, in the year of our Lord One
thousand eight hundred and forty-nine.