IMPROVEMENTS IN STEREOTYPING
Year: 1856

page_text: LETTERS PATENT to James Hogg, Publisher, South Blacket Place, and
John Napier, Stereotyper, East Sciennes Street, both of Edinburgh, in
the County of Edinburgh, for the Invention of "IMPROVEMENTS IN
STEREOTYPING."
PROVISIONAL SPECIFICATION left by the said James Hogg and John
Napier at the Office of the Commissioners of Patents, with their Petition,
on the 5th April 1856.
We, JAMES HOGG and JOHN NAPIER, do hereby declare the nature of the
said Invention for IMPROVEMENTS IN STEREOTYPING, to be as follows:-
This Invention consists of certain improvements in the methods of manu-
facturing the metallic plates used by letterpress printers, and denominated by
them "stereotype plates," the said improvements having reference to processes
by which a matrix is first taken from the types or other raised or sunk surface
of which a counterpart is desired, and also to the processes by which a metallic
copy
is taken from the matrix, the substance of which this copy is composed
being any convenient alloy of metals, such as is presently in use for the
manufacture of types or stereotype plates.

page_text: The first part of the Invention relates to the formation of the matrices, and
is as follows-Firstly, a thick viscid paste is to be prepared, by the intimate
adınixture in equal quantities of the earthy substances called red ochre and fine
whiting, together with a sufficient quantity (also in about equal proportions) of
prepared thin glue, and starch, and wheaten flour, made up into a paste, a
little alum being included. Of the glue and paste, there is to be employed
just as much as is necessary, when all the components have been properly
mixed, to make the compound a stiff past or magma. A quantity of this
paste is then to be spread with a knife or other suitable instrument upon the
surface of a piece of stout packing paper, cloth, or other suitable fabric, and
having been first spread as evenly as possible, a straight edge of any con-
venient kind is passed over it, so that the coating of paste may be rendered
uniform in thickness. The amount of paste spread on should be about equal
to the thickness of a threepenny piece, as that coin is at present issued from
Her Majesty's Mint. This combination of paste and packing paper, cloth, or
other convenient substance, is now to be allowed to stand under the influence
of the atmosphere for about half an hour, until the surface becomes nearly dry.
In forming the paste, which produces the surface of the matrix, it is to be
understood that we do not confine ourselves to the exact ingredients or pro-
portions herein-before specified, various earthy substances in different propor-
tions may be employed, but those mentioned we find preferable; but let it be
distinctly understood that the liquid glue and paste are essential ingredients
in the composition, incorporating the earthy substances which it
may be found
convenient to employ.
The "page" or "form," of which a cast is required to be taken, is now to
be laid down with the face uppermost, a slight coating of lard or other oil
being brushed over them, and the flat matrix laid down upon the face of the
types or "form," that surface upon which the paste or composition has been
spread being next the oiled face of the "form." In this condition the whole
is to be subjected to slight pressure in a printing press or other convenient
apparatus, sufficient to press firmly and evenly the matrix into the face of the
types upon which it has been laid. A single and very light "soaking" pull
at a printing or other convenient press is sufficient for the purpose, or the
impression may be taken by the implements known to printers as a "planer
and mallet," used in the same way as when "planing over" a form of types.
After the impression is obtained the matrix must not be moved from contact
with the "form" until it has been dried, and while this is going on it is
necessary to place a weight of some sort upon the back of the matrix until it
is sufficiently dry. The best way is to place the bottom of the "form" or

page_text: ".
page" [where the words "page" or "form" are used, it is to be understood
that these phrases include one or more pages or portions of pages of combined
types or woodcuts, or any other raised or sunk surfaces, of which a counter-
part may be required,] upon a plate of heated metal, keeping at the saine
time some flat heavy weight upon the back of the matrix. In a short time,
varying according to the amount of heat applied, the matrix will have dried
whilst lying upon the face of the "form," and when withdrawn therefrom,
will be found to afford an exact reverse copy of the "form" or "page"
operated upon. This is the first method of forming the improved matrix.
The advantages which it presents over the gypsum or plaster of Paris pro-
cess now in use are, (1,) either high or low "spaces," "quadrats," or "leads"
(in the case of combined types) may be used, and thus all "stuccofying"
or filling up with plaster the low portions of the form to be cast from
is avoided; (2,) the matrices are much sooner ready for casting, less time
being occupied in the preparation and drying of these; (3,) less "picking"
is required, and the types after being cast from are returned to the compositor
in a cleaner state.
The advantages which it presents over the paper process now in use are,
(1,) the matrix requires less time for preparation; (2,) from only a slight
pressure in any sort of press, or a stroke on a piece of flat wood or metal laid
on the back of the matrix being necessary to produce an impression, injury to
the types is avoided, the damage caused by beating in the paper mould with
a brush being entirely obviated; (3,) "kerned" or projecting letters are not
liable to be broken as in the process of beating in the matrix.
The second method of forming an improved matrix is as follows:-Pul-
verised gypsum or plaster of Paris, such as is commonly used in stereotyping,
is to be mixed with water in such quantity as will make a mixture of the
consistency of thick cream. The "form" or "page to be operated upon is
then to be laid down, and a ledging of any convenient sort, about one-tenth of
an inch higher than the "form," so joined at the edges as to retain the liquid
plaster on the surface of the types, and at the same time form the thickness
of the necessary coating of plaster, is to be placed round the "form." A thin
coating of the cream-like mixture of plaster of Paris is then to be poured over
the surface of the "form" to a level with the outside ledging, thus leaving a
coating of plaster about one-tenth of an inch above the face of the "form."
A small roller is then to be passed over the face of the "form" to expel the
air. There is then to be laid down on
ported by the ledging which surrounds
just touch the plaster, an iron or other
the top of the said coating and sup-
the "form," so that the surface will
metallic or earthenware plate, from

page_text: one-fourth to half an inch in thickness, of the kind represented in Figures
1 & 2 in the accompanying Drawings.
Figure 1 represents a plan view of the under surface of the plate; Figure 2
represents a plan view of the upper surface of the plate. The letters a, a, in
Figure 1, refer to holes or perforations throughout the body of the plate; the
letters b, b, in Figure 2, refer to grooves in the upper surface of the plate.
Having, we say, laid down this plate in such a manner that its under surface
shall touch the plaster coating with which the surface of the "form" is
covered, we then proceed to pour upon the upper surface of the said plate
more liquid plaster, made as before of a cream-like consistency. The plate
being perforated with a series of holes (as shown in Figures 1 and 2), the
plaster runs through all these and comes into contact with that coating spread
upon the surface of the "form." As much plaster is to be run on the upper
surface of the plate as will fill up the grooves marked b, b, in Figure 2, when
an ordinary straight edge is to be drawn across the top of the plate, so as to
remove all surplus plaster, and leave the back of the plate flat. In a short
time the plaster will have "set" or solidified, and, consequently, the matrix
formed by the perforated plate and the plaster will be capable of being with-
drawn in a solid mass from the face of the "form." That portion of the
matrix formed by the portions of plaster lying between the face of the types
and the under surface of the plate will be found to present an exact copy in
reverse of the face of the "form" operated upon. In order to prepare this
matrix for being cast from, like any plaster matrix presently employed, it is
only necessary that it be dried on a hot plate, or slowly baked in an oven for a
sufficient time in the ordinary manner.
A modification of the plate may be used thus:-Instead of perforations in
the body of the plate, there are to be placed on its under side a series of
1-shaped (or other) projections resembling buttons, each button having a neck
about th to th of ar. inch long between its head & the body of the plate.
In this case the ledging round the "form" to be stereotyped must be higher
than when the perforated plate is used; this is necessary, in order to admit of
the projections sinking into the plaster without actually coming into contact
with the face of the "form." In other respects the mode of operating is
the same; the perforated plate, however, is preferred.
The advantages which the method now detailed affords in preference to a
matrix wholly composed of plaster as at present in use, are as follows:-
(1.) It is much sooner ready to cast from, that is to say, it is sooner baked
or dried than a matrix wholly composed of plaster, as at present; for, in the
methods herein-before described, there being only a surface of plaster with a

page_text: series of plaster pins or nipples (or collars, round button-shaped projections) of
the plate, it follows, that there is a less body of plaster to be dried, and also by
the said pins or nipples being surrounded on all sides with metal or earthen-
ware, the matrix when laid upon a hot plate or the shelf of an oven has the
heat readily and equally conveyed to all its parts.
(2.) It will afford a much "flatter" stereotype than can at present be
obtained from a matrix composed altogether of plaster of Paris; that is to say,
the metal plate which is taken from the said improved matrix herein-before
described, will be found to have a surface more nearly a true plane; for, in the
case of a plate or cast taken from a matrix composed altogether of plaster, as
at present, it is found that the evaporation of water from the plaster whilst
it is being baked, causes the surface to "warp" very much, and consequently
the corresponding stereotype copy partakes of this warping, as regards the
inequality of surface, which inequality is found by practical printers to be a
source of much trouble and annoyance in preparing the stereotype plates for
working at press or machine, since good workmanship requires the type or
plate surface to be as nearly as is possible a true plane.
We come now to describe the second part of the Invention, being that part
which relates to the employment of a matrix formed according to either of the
methods described under the first part, for the production or manufacture of a
copy in metal, said copy being the actual stereotype plate.
a
Figure 3 represents a sectional view of a casting box, composed of two iron
plates, each about one-half inch in thickness (marked a and b), planed smooth.
Figure 4 represents a casting box composed of fire brick and metal.
represents a sectional view of a large fire brick or slab of baked clay, quite
smooth on the surface; b represents a sectional view of an iron plate, planed
smooth.
Figure 5 is a plan view of the sole of an iron plate, such as those portions
marked X in the sectional view b, Figures 3 & 4. In Figure 5 the sole is
represented as having lying upon it a matrix (marked a and coloured red), and
sundry slips of flat iron or wood (marked b, b, b, coloured yellow).
Figure 6 represents a plan view of the interior surface of the perpendicular
flange part of plate 6; the portion of this interior surface marked y, in
Figure 6, is cut out to an extent equal to about one-half of the thickness of
the said plate or flange.
Figure 7 represents a sectional view of a casting box of any convenient size,
in shape similar to the flat pan in common use, but about two inches deeper,
and in which the ordinary float plate is taken away, and a series of thin plates
substituted.

page_text: Figure 8 represents merely a plan view of the top or cover of the casting
box, shown in sectional view in Figure 7. The corners of Figure 8 show
portions cut out, to allow the ingress of the fluid metal and the escape of air
simultaneously.
Having explained the meaning of these several Figures, it is simply neces-
sary that we declare they show the improved methods we employ for casting a
metal copy from the matrix, prepared according to either of the methods set
forth under the first head of this Specification; that is to say, we use as a
casting box two plates of metal, shaped according to the sectional view given
in Figure 3, and of which the superficies shall be of any convenient extent,
according to the size of the matrix from which a copy is to be taken.
To pre-
pare for casting, we first heat in an oven, having a temperature of about 450°
Fahrenheit, the metal plates marked a and b, and (when irou is used) also the
flat metal slips marked b, b, b, and coloured yellow in Figure 5. Having
heated these plates and slips to a degree nearly equivalent to the heat of the
oven, we then lay upon the sole of the plate 6 (Fig. 3), the three flat slips of
iron or wood, in such manner as is shown in the plan view, Figure 5. Inside
these flat slips of iron or wood is to be laid the matrix with its face uppermost,
in the same manner as is represented by a in Figure 5. The sides of the
matrix are to be allowed slightly to underlap the flat iron slips b, b, in order
that the matrix may be held fast to the sole. The upper plate a (Figure 3) is
then to be laid upon plate 6, in such manner that their perpendicular flanges
(as shown in Figure 3) may lie closely together. The matrix and the casting
box are now ready to receive the fluid metal or alloy, which is to be employed
to form the actual stereotype plate. This fluid metal or alloy (of the kind
ordinarily employed by stereotypers or type founders) is to be poured between
the flanges of the plates, in the direction shewn by the arrow in Figure 3. By
means of the aperture in the flange of plate (as shewn in y, Fig. 6,) the
metal flows into the sole, and being prevented from escaping by the flat slips
of metal or wood (b, b, b, Fig. 5), it surrounds and falls into the surface of the
matrix. As much metal is to be poured in as will fill the casting box up to
the top of the aperture y in the flange of plate b. This is for the purpose of
exerting a pressure on the metal in the sole of the casting box, which pressure
causes the fluid metal or alloy to run sharply into all the minute cuttings
in the surface of the matrix. It is immaterial as regards the process of casting
whether the matrix to be inserted into the casting box just described be formed
according to the first or second method herein-before described under the first
part of this Specification. The only variable detail is as regards the thickness
of the flat metal or wooden slips (b, b, b, Fig. 5), which surround the matrix

page_text: and keep it fast to the sole of the iron plate b. The height or thickness of
these flat metal or wooden slips is to be regulated by the thickness of the
matrix inserted into the casting box and the thickness. of the stereotype which
is required. to be cast.
5. A modification of the casting box is shown in Figure 4. In this case there
is substituted for the iron plate a (Fig. 3) a large brick or slab of fine fire clay
or other suitable non-conducting substance, smooth upon the surface, having a
thickness equal to 4 or 5 inches, and a superficies of any convenient extent. This
brick or slab of fire clay is represented by a in Figure 4. It is simply employed
as a substitute for the iron plate a, which has been herein-before described.
When used, it is to be first heated in the same manner as the plates a and b
(Fig. 3). The use of the brick or slab is to prevent the fluid metal or alloy
from cooling too quickly after it has been poured into the mould, of which the
said brick or slab forms part.
Another modification of casting box or mould is referred to in Figures
7 and 8. The matrix is to be placed at the bottom of the pan, and others (if
found convenient) upon the intermediate plates, shown in the Drawing; these
being kept apart by slips of iron or wood, sufficient to form the thickness of
stereotype desired (as shown in Figure 5). The top is then to be fixed down,
and the fluid metal or alloy poured in just as in the ordinary flat pan when not
dipped in a bath of metal or alloy; or, like the flat pan, also it may, if
convenient, be dipped into a bath of molten alloy.
After the fluid metal has become sufficiently cool, it will be found that the
surface next to the matrix (formed according to either of the methods herein-
before laid down in this Specification) presents an exact fac-simile of the face
of the "form," of which the matrix formed a reverse copy. The face of par-
ticular letters may be "picked or remedied in the ordinary manner; the
back of the plate being planed and its sides trimmed and dressed likewise
in the ordinary manner to fit it for press.
It is to be distinctly understood that we do not claim the exclusive right of
manufacturing stereotype plates by means of matrices formed of an earthy
substance, such as whiting or pulverised gypsum or plaster of Paris, but what
we do claim as novel and of our Invention, is,-
Firstly, the placing in IMMEDIATE CONTACT with the face of the "form" a
composition similar to that described under the first head of the first part of this
Specification, capable of forming a matrix, which after being subjected to FLAT
PRESSURE [i. e. pressure however exerted, which is distributed equally at the
same moment] upon the faces of the "form" or pages of types or other raised
or sunk surfaces to be stereotyped, and then dried in the manner likewise set

page_text: forth under the first head of the first part of the Specification, produces a
reverse copy of the said "form" or "page" of types or other raised or sunk
surface which it is required to stereotype.
Secondly, the combination and application, as herein-before described under
the second head of the first part of this Specification, of an iron or other
-metallic or earthenware plate, with gypsum or plaster of Paris sO UNITED as to
form a matrix, for the purpose of obtaining stereotype plates.
Thirdly, the combinations and applications of iron and of iron and brick
termed "casting boxes" or moulds, herein-before set forth under the second
part of this Specification, and referred to in Figures 3, 4, 5, 6, 7, 8, of the
accompanying Drawings, the said "casting boxes" or moulds being capable, in
conjunction with suitable matrices (as described under the first part of the
Specification), (and referred to in Figures 1 and 2 of the accompanying
Drawings), of producing "stereotype plates."
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said James Hogg and John Napier in the Great Seal Patent
Office on the 3rd October 1856.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, JAMES
HOGG, Publisher, South Blacket Place, and JOHN NAPIER, Stereotyper, East
Sciennes Street, both of Edinburgh, in the County of Edinburgh, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fifth day of April, A.D. 1856, in the twentieth year
of Her reign, did, for Herself, Her heirs and successors, give and grant unto
us, the said James Hogg and John Napier, Her special license that we, tho
said James Hogg and John Napier, our executors, administrators, and assigns,
or such others as we, the said James Hogg and John Napier, 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 STEREOTYPING," upon the condition
(amongst others) that we, the said James Hogg and John Napier, by an
instrument in writing under our 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 Office of the

page_text: Commissioners of Patents for Inventions within six calendar months next
and immediately after the date of the said Letters Patent.
NOW KNOW YE, that we, the said James Hogg and John Napier, do
hereby declare the nature of our said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and by the
following statement (that is to say) :-
This Invention consists of certain improvements in the methods of manu-
facturing the metallic plates used by letterpress printers, and denominated
"stereotype plates," the said improvements having reference to processes by
which a matrix is first taken from the types, or other raised or sunk surface,
of which a counterpart is desired, and also to the processes by which a metallic
copy is taken from the matrix; the substance of which this copy is composed
being any convenient alloy of metals, such as is presently in use for the manu-
facture of types or stereotype plates.
The first part of the Invention relates to the formation of the matrices,
and is as follows:-Firstly, a thick viscid paste is to be prepared by the
intimate admixture, in about equal quantities, of the carthy substances called
red ochre and fine whiting, together with a sufficient quantity (also in about
equal proportions) of prepared thin glue and starch and wheaten flour made up
into a paste, a little alum being included in the latter compound. Of the gluo
and paste there is to be employed just as much as is necessary when all the
components have been properly mixed, to make the compound a stiff paste or
magma. A quantity of this paste is then to be spread with a knife or other
suitable instrument upon the surface of a piece of stout packing paper, cloth,
or other suitable fabric, and having been first spread as evenly as possible, a
straight edge of any convenient kind is passed over it, so that the coating of
paste may be rendered uniform in thickness. The amount of paste spread on
should be about equal to the thickness of a threepenny piece, as that coin is
at present issued from Her Majesty's mint. This combination of paste and
packing paper, cloth, or other convenient substance, is now to be allowed to
stand under the influence of the atmosphere for about half an hour, until the
surface becomes nearly dry. In forming the paste which produces the
surface of the matrix, it is to be understood that we do not confine ourselves
to the exact ingredients or proportions herein-before specified. Various eartby
substances in different proportions may be employed, but those mentioned we
find preferable. But let it be distinctly understood that the liquid glue and
paste are essential ingredients in the composition incorporating the earthy
substances it may be found convenient to employ.
The "page" or "form" of which a cast is required to be taken is now to
be laid down with the face uppermost, a slight coating of lard or other oil
'

page_text: being brushed over them, and the flat matrix laid down upon the face of the
types or "form;" that surface upon which the paste or composition has been
spread being next the oiled face of the "form." In this condition the whole
is to be subjected to slight pressure, in a printing-press, or other convenient
apparatus, sufficient to press firmly and evenly the matrix into the face of the
types upon which it has been laid. A single, and very, light. " soaking" pull at
a printing or other convenient press is sufficient for the purpose; or the
impression may be taken by the implements known to printers as a "planer
and mallet," used in the same way as when "planing over ' a form of types.
After the impression is obtained, the matrix must not be moved from contact
with the "form" until it has been partially dried; and while this is going on,
it is necessary to place a weight of some sort upon the back of the matrix. The
best way is to place the bottom of the "form" or page [where the words
"page" or "form" are used, it is to be understood that these phrases include
one or more pages or portions of pages of combined types or woodcuts, or
any other raised or sunk surfaces, of which a counterpart may be required,]
upon a plate of heated metal, keeping at the same time some flat heavy
weight upon the back of the matrix... In a short time (varying according to
the amount of heat applied) the matrix will have partially dried whilst lying
upon the face of the "form," and when withdrawn therefrom will be found to
afford an exact reverse copy of the "form" or "page" operated upon. This
is the first method of forming the improved matrix.
66
The advantages which it presents over the gypsum or plaster of. Paris
process now in use are; (1,) either high or low "spaces," "quadrats," or
"leads" (in the case of combined types) may be used, and thus all "stuc-
cofying" or filling up with plaster the low portions of the "form" to be cast
from is avoided; (2) the matrices are. much sooner. ready for casting, less
time being occupied in the preparation and drying of these; (3,) less
"picking" is required, and the types cast from are returned to the compositor
in a cleaner state.
The advantages which it presents over the paper process now. in use are, (1,)
the matrix requires less time for preparation; (2) from only a slight pressure
in any sort of press, or a stroke on a piece of flat wood or metal laid on the
back of the matrix, being necessary to produce an impression, injury to the
types is avoided, the damage caused by beating. in the paper mould with a
brush being entirely obviated; (3,) "kerned" or projecting letters are not
liable to be broken, as in the process of beating in the matrix.
The second method of forming an improved matrix is as follows:-
Pulverised gypsum or plaster of Paris, such as is commonly used in stereo-
typing, is to be mixed with water in such quantity as will make a mixture of

page_text: the consistency of thick cream. The "form" or "page "-to be operated upon
is then to be laid down, and a ledging of any convenient sort, about one-
tenth of an inch higher than the "form," so joined at the edges as to retain
the liquid plaster on the surface of the types, and at the same time form the
thickness of the necessary coating of plaster, is to be placed round the "form."
A thin coating of the cream-like mixture of plaster of Paris is then to be
poured over the surface of the "form," to a level with the outside ledging.; thus
leaving a coating of plaster of Paris about one-tenth of an inch above the face
of the "form." A small roller is then to be passed over the face of the
"form," to expel the air. There is then to be laid down on the top of the
said coating, and supported by the ledging which surrounds the " form," so
that the surface will just touch the plaster, an iron or other metallic or earthen-
ware plate, from one-fourth to half an inch in thickness, perforated with holes
throughout the whole body of the plate, and grooved on the upper side.
Having laid down this plate in such a manner that its under surface shall
touch the plaster coating with which the surface of the "form" is covered,
we then proceed to pour upon the upper surface of the said plate more
liquid plaster, made, as before, of a cream-like consistency. The plate
being perforated with a series of holes, the plaster runs through all these, and
comes into contact with that coating spread upon the surface of the "form."
As much plaster is to be run on the upper surface of the plate as will fill up.
the grooves on the back, when an ordinary straight edge is to be drawn across
the top of the plate, so as to remove all surplus plaster, and leave the back of
the plate flat. In a short time the plaster will have "set," or solidified, and
consequently the matrix formed by the perforated plate and the plaster will
be capable of being withdrawn in a solid mass from the face of the "form."
That portion of the matrix formed by the portions of plaster lying between.
the face of the types, and the under surface of the 'plate will be found to
present an exact copy in reverse of the "form" operated upon. In order to.
prepare this matrix for being cast from, it is essential that it be very gradually
and carefully dried on a hot plate, or in an oven with a slowly increasing heat,
till all moisture has completely evaporated.
A modification of the plate may be used thus:-Instead of perforations in
the body of the plate, there are to be placed on its under side a series of
1 shaped (or other) projections resembling buttons,' each button having a neck
about one-tenth to one-twentieth of an inch long between its head and the
body of the plate. In this case, the ledging round the "form" to be stereo-
typed must be higher than when the perforated plate is used. This is neces-
sary, in order to admit of the projections sinking into the plaster without

page_text: coming into contact with the face of the "form." In other respects the
mode of operating is the same. The perforated plate, however, is preferred.
The advantages which the method now detailed affords, in preference to a
matrix wholly composed of plaster, as at present in use, are as follow:-
(1.) There being only a surface of plaster, with a series of plaster pins or
nipples (or collars having round button-shaped projections) on the plate, it
follows that there is a much less body of plaster to be dried, and also by the
said pins or nipples being surrounded on all sides with metal, the matrix when
laid upon a hot plate has the heat readily and equally conveyed to all its parts.
(2.) It will afford a much "flatter" stereotype than can at present be
obtained from a matrix composed altogether of plaster of Paris. That is to
say, the metal or stereotype plate which is taken from the said improved
matrix herein-before described will be found to have a surface more nearly a
true plane. For, in the case of a plate or cast taken from a matrix composed
altogether of plaster as at present, it is found that the evaporation of water
from the plaster whilst it is being baked, causes the surface to "warp" very
much, and consequently the corresponding stereotype copy partakes of this
"warping," as regards the inequality of surface, which inequality is found by
practical printers to be a source of much trouble and annoyance in preparing
the stereotype plates for working at press or machine; since good workman-
ship requires the type or plate surface to be as nearly as possible a true plane.
We come now to describe the second part of the Invention, being that part
which relates to the employment of a matrix, formed according to either of
the methods described under the first part, for the production and manufacture
of a copy in metal, said copy being the actual stereotype plate.
(1.) We use as a casting box two plates of metal, of which the superficies
shall be of any convenient extent, according to the size of the matrix from
which a copy is to be taken, and each having also a rectangular flange of 5 or
6 inches. To prepare for casting, we first heat in an oven, having a temperature
of 450° Fahrenheit, the metal plates, also the gauge necessary to form the
required thickness of stereotype plate. Having heated these plates and gauge,
we then lay the matrix between the two iron plates, surrounded by the gauge,
and bind the whole together by means of any convenient iron cramp. The
sides of the matrix are to be allowed slightly to underlap the gauge, in order
that the matrix may be held fast. The matrix and the casting box are now
ready to receive the fluid metal or alloy which is to be employed to form the
actual stereotype plate. This fluid metal or alloy is of the kind ordinarily
employed by stereotypers or type-founders. It may either be poured simply
into the aperture between the two iron plates when held apart by the gauge,

page_text: or it may be poured between the flanges of the two iron plates. In the latter
case, a portion of one of the flanges is filed out, in order to let the fluid alloy
run down on the face of the matrix. The gauge also must be adapted so as
to keep the fluid alloy from escaping from between the iron plutes. As much
metal is to be poured in as will fill the casting box, which should always be
somewhat larger than the matrix to be cast from. This is for the purpose of
exerting a pressure on the metal in the casting box, which pressure causes the
fluid metal or alloy to run sharply into all the minute cuttings in the surface
of the matrix. It is immaterial, as regards the process of casting, whether the
matrix to be inserted into the casting box just described be formed according
to the first or second method herein-before described under the first part of
this Specification. The only variable detail is as regards the thickness of the
gauge which surrounds the matrix, and keeps it fast between the iron plates,
while preventing the fluid alloy from escaping before it "sets."
(2.) A modification of the above casting box may be used thus:-A large
brick or slab of fine fire-clay or other suitable non-conducting substance, smooth
upon the surface, having a thickness equal to 4 or 5 inches, and a superficies
of any convenient extent may be substituted for one of the iron plates. It
is simply employed as a substitute for the said iron plate. When used it is
to be first heated in the same manner as the iron plates. The use of the brick
or slab is to prevent the fluid metal or alloy from cooling too quickly after it
has passed into the mould of which the said brick forms part. The brick and
plate, with the matrix and gauge lying between them, are to be "cramped'
together just in the same manner as the two iron plates.
"
"
(3.) Another modification of casting box or mould may be formed thus:-
The matrix is to be placed at the bottom of an iron pan (called "flat pans
amongst stereotypers, but having rather higher sides), and other matrices (if
found convenient) laid upon intermediate iron plates, these being kept apart
by gauges running round any three sides of the matrix sufficient to form the
thickness of the stereotype plates desired. An iron top or cover of the ordinary
sort attached to a "flat pan" is then to be fixed down, and the fluid metal or
alloy poured in, just as in the ordinary "flat pan" used at present in stereo-
typing when not dipped in a bath of metal or alloy. Or, like the "flat pan
also it may, if convenient, be dipped into a bath of molten alloy. Before
inserting the matrices (if formed according to the first method laid down in
the first part of this Specification) in this form of casting box, they should
be carefully coated on the back with a thin coating of the compound which
forms the face of the matrix. This keeps them from charring too much when
exposed to the hot fluid alloy.
"

page_text: By any of these three methods, after the fluid metal has become sufficiently
cool, it will be found that the surface next to the matrix (formed according to
either of the methods herein-before laid down in this Specification) presents an
exact fac-simile of the face of the "form," of which the matrix formed a
reverse copy. The face of particular letters may be "picked" or remedied in
the ordinary manner, the back of the plate being planed, and its edges trimmed
and dressed likewise in the ordinary manner to fit it for press.
It is to be distinctly understood, that we do not claim the exclusive right of
manufacturing stereotype plates by means of matrices formed of an earthy
substance such as whiting or pulverised gypsum or plaster of Paris; neither
do we claim as of our Invention the application of "flat pans," as they are
commonly called for the purposes of a stereotype "casting box;" but what we
do claim as novel and of our Invention is,-
Firstly, the placing in immediate contact with the face of the "form" a
composition similar to that described under the first head of the first part of
this Specification, capable of forming a matrix, which, after being subjected to
flat pressure [that is, pressure, however exerted, which is distributed equally
at the same moment] upon the faces of the "form" or pages of type, or other
raised or sunk surfaces to be stereotyped, and then dried in the manner like-
wise set forth under the first part of this Specification, produces a reverse copy
of the said "form" or pages of types, or other raised or sunk surface, which it
is required to stereotype.
Secondly, the combination and application, as herein-before described under
the second head of the first part of this Specification, of an iron or other
metallic or carthenware plate, with gypsum or plaster of Paris, so united as to
form a matrix for the purpose of obtaining stereotype plates.
་་
Thirdly, the combinations and applications of iron, and of iron and brick,
termed " casting boxes or moulds, herein-before set forth under the second
part of this Specification.
In witness whereof, we, the said James Hogg and John Napier, have
heretofore set our hands and seals, this Thirtieth day of September,
Anno Domini One thousand eight hundred and fifty-six.