AN IMPROVEMENT IN THE MANUFACTURE OF ENVELOPES
Year: 1856

page_text: LETTERS PATENT to William Warren, of Northampton Park, Gentleman,
and Warren De la Rue, of Bunhill Row, Manufacturer, both in the
County of Middlesex, for the Invention of "AN IMPROVEMENT IN THE
MANUFACTURE OF ENVELOPES."
Sealed the 24th June 1856, and dated the 14th April 1856.
PROVISIONAL SPECIFICATION left by the said William Warren and
Warren De la Rue at the Office of the Commissioners of Patents, with
their Petition, on the 14th April 1856.
We, WILLIAM WARREN, of Northampton Park, Gentleman, and WARREN
DE LA RUE, of Bunhill Row, Manufacturer, both in the County of Middlesex,
do hereby declare the nature of the Invention for "AN IMPROVEMENT IN THE
MANUFACTURE OF ENVELOPES," to be as follows:-
This Invention has for its object an improvement in the manufacture of
envelopes with a view to prevent any writing or printing being read through
For this purpose, in place of making up envelopes of plain paper,
or paper of an uniform color all over the interior surfaces, such interior surfaces
are broken up by being printed or ruled in, or with patterns with colors
different from that of the paper, by which, on looking through an envelope from
the exterior, even though the paper may be to a considerable degree trans-

page_text: parent, the pattern produced on the interior surface renders the whole interior
confused, and prevents any part of the letter, note, or document being read
through the envelope.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Warren and Warren De la Rue in the Great Seal
Patent Office on the 9th October 1856.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, WILLIAM
WARREN, of Northampton Park, Gentleman, and WARREN DE LA RUE, of
Bunhill Row, Manufacturer, both in the County of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fourteenth day of April, in the year of our Lord One
thousand eight hundred and fifty-six, in the nineteenth year of Her reign, did,
for Herself, Her heirs and successors, give and grant unto us, the said William
Warren and Warren De la Ruc, Her special licence that we, the said William
Warren and Warren De la Rue, our executors, administrators, and assigns,
or such others as we, the said William Warren and Warren De la Rue, 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 "AN IMPROVEMENT IN THE MANUFACTURE OF
ENVELOPES," upon the condition (amongst others) that we, the said William
Warren and Warren De la Rue, our exccutors or administrators, by an
instrument in writing under our, or their hands and seals, or under the hand
and seal of one of us or them, should particularly describe and ascertain the
nature of the said Invention, and in what manner the same was to be per-
formed, and cause the same to be filed in the Great Seal Patent Office within
six calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said Warren De la Rue, on behalf of myself
and the said William Warren, do hereby declare the nature of the said In-
vention, and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement thereof, that is
to say:
This Invention has for its object an improvement in the manufacture of
envelopes with a view to prevent any writing or printing being read through

page_text: the same. For this purpose, in place of making up envelopes of plain paper, or
paper of an uniform color all over the interior surfaces, such interior surfaces
are broken up by being printed or ruled in, or with patterns with colors
different from that of the paper, by which, on looking through an envelope from
the exterior, even though the paper may be to a considerable degree trans-
parent, the pattern produced on the interior surface renders the whole interior
confused, and prevents any part of the letter, note, or document being read
through the envelope.
In order that the nature of our Invention may be understood, we may
premise that all writing paper, unless of great thickness, is more or less trans-
parent, so that writing may be frequently read through a thickness of paper
placed over it. This transparency of writing paper has been found of great
inconvenience when employed for envelopes for enclosing letters and documents
to be transmitted by post or entrusted to messengers, and has led to various
attempts to render the paper employed in the manufacture of envelopes less
translucent. Among other plans we would mention the manufacture of paper
composed of two sheets of paper veneered or pasted together, the one colored
and the other white, the colored side forming the inside of the envelope.
More recently one of us, as a partner in the house of Thomas De la Rue
& Co., manufactured envelopes made of paper colored on the one side with body
colors. The foregoing descriptions of envelopes have, to some extent, the desired
property of preventing writing from being read through the enclosing envelope,
but not so effectually as could have been desired. In order to obtain the
greatest possible non-transparency we bave made various experiments, which
resulted in showing that the practical opacity of envelopes could be best obtained
by printing on the inner side of them an ornamental pattern covering the
surface completely, and of the character known as an all-over ground. The
pattern we prefer should be as full as possible, and composed of fine lines, which
produce so much confusion with the lines of writing on the enclosed letter that
it is not possible to decipher such writing.
We prefer combining the printing with a previous coloring of the paper,
preferring to use body colors for such purpose. The printing we produce by
any of the well-known means; as, for example, surface or typographical
printing, lithography, or copper-plate and cylinder printing, giving preference
however to surface printing, using ordinary black, or it may be other printing
ink. We are quite aware that for the purposes of advertisement, or giving
instruction as to the transmission of an answer, it has been customary ocen-
sionally to issue envelopes partly printed with letter-press on the inside. We
therefore disclaim such employment of such letter-press printing in the inside

page_text: of envelopes; the printing we employ being of. an all-over pattern and of an
ornamental character, in order to prevent the reading of letters or other
documents through the envelope.
In witness whereof, I, the said Warren De la Rue, have hereunto set
my hand and seal, this Sixteenth day of September, in the year of
our Lord One thousand eight hundred and fifty-six.
Witness,
FREDERICK WESTCOTT FRY,
110, Bunhill Row.
WARREN DE LA RUE. (L.S.)