AN IMPROVEMENT IN THE MANUFACTURE OF METALLIC LETTERS, FIGURES, AND OTHER DEVICES
Year: 1841

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHRISTOPHER
DUMONT, of No. 4, Mark Lane, in the City of London, Gentleman, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent under the Great Seal of Great Britain, bearing date at Westminster,
the Twenty-second day of May, in the fourth year of Her reign, did, for
Herself, Her heirs, and successors, give and grant unto me, the said
Christopher Dumont, my exors, admors, and assigns, Her especial licence,
full power, sole privilege authority, that I, the said Christopher Dumont, my
exors, adñiors, and assigns, and such others as I, the said Christopher
Dumont, my exors, admors, and assigns, should at any time agree with, and
no others, from time to time and at all times hereafter during the term of years
therein mentioned, should and lawfully might make, use, exercise, and vend,
within England, Wales, and the Town of Berwick-upon-Tweed, my Invention
of "AN IMPROVEMENT IN THE MANUFACTURE OF METALLIC LETTERS, FIGURES, AND
OTHER DEVICES;" in which said Letters Patent there is contained a proviso that
I, the said Christopher Dumont, shall cause a particular description of the
nature of my said Invention, and in what manner the same is to be performed,
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 months next

page_text: immediately after the date of the said in part recited Letters Patent, as, upon
reference thereunto, will fully appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Christopher Dumont, do hereby declare, the "nature of my said Invention"
consists in an improvement in the manufacture of letters, figures, and other
devices, adapted for inscriptions upon houses, shops, sign boards, and other
similar purposes, by stamping or pressing and at the same time cutting them
out of thin metallic plates.
I will now proceed to describe "in what manner the same is to be per-
formed." A model or pattern of the letter or figure or other device required
is first to be prepared in wood or wax, in the manner well known to modellers or
pattern makers, but with this difference or addition in the preparation of the
same to that which is usual:-Around the outside edges of the said model or
pattern there is to be formed a V groove, in order to produce therefrom in the
casting a projecting angular edge around the casting, which will be best explained
by a simple example. Suppose it be required to produce the Roman letter I
in relief, and of convex form in its transverse section, as is intended to be repre-
sented by the Diagram marked Figure 1 in the margin; around this Figure
is made the V groove just mentioned, and as expressed in Figure 1 by the
blue border around it. Let a cast of this model be taken in gypsum (plaister
of Paris), and the result will be the same figure in reverse as represented by
Figure 2, which exhibits a transverse section through the line a, b, in Figure 1.
From this gypsum model a die is to be formed, either of steel or of cast iron,
of exactly the same figure. This constitutes the lower die, and is also repre-
sented by Figure 2. Into this lower die is then poured zinc or some other
metallic body of equal hardness, to make what is technically denominated a
force," which is used as an upper die, and is represented by Figure 3. As
a measure of economy, I make the lower die of the finer or purer kind of cast
iron, and afterwards finish the same in the manner well known to die sinkers
and founders, attention being particularly paid to perfecting the V edge, in
order that when the thin metal plate is placed upon it, and the "force" is
applied, the metal may be cleanly cut through, so as to require but little or no
dressing at the edges afterwards. By the employment of suitable dies on
the same principle of construction, all kinds of letters, figures, and other
devices may, of course, be produced in great perfection, and with great
economy, both in respect to material and labour, as the form is produced
and cut out by a single blow.
66
Having now explained the nature of my Invention, and the manner in
which it may be efficiently performed, I desire it to be distinctly understood,

page_text: that I do not limit my claim to the exact method set forth, as the same or
similar results may be obtained by considerable modifications of my said
described method. But what I do claim as original and of my Invention, is the
improved manufacture of letters, figures, and other devices in relief, by
stamping or pressing and cutting them out of thin metallic plates. And such
my Invention being, to the best of my knowledge and belief, entirely new in
this Kingdom, I hereby declare my intention to maintain an exclusive privilege
for the same.