IMPROVEMENTS IN ENVELOPES
Year: 1877

page_text: LETTERS PATENT to Alfred Mackrill, of Whitefriars Street, in the City of
London, for the Invention of "IMPROVEMENTS IN ENVELOPES."
PROVISIONAL SPECIFICATION left by the said Alfred Mackrill at the Office
of the Commissioners of Patents on the 31st July 1877.
ALFRED MACKRILL, of Whitefriars Street, in the City of London.
MENTS IN ENVELOPES."
"
'IMPROVE-
My Invention relates more particularly to envelopes intended for the transmission
of registered letters, bank notes, and other valuables or documents by post, and it
consists in so interlocking and otherwise uniting or securing the various folds or
flaps of the envelope together that it is absolutely impossible that it can be tampered
with or any of the contents surreptitiously abstracted without being immediately
detected by the most casual observer, since access cannot be had to the interior
without disfiguring and in fact partially destroying the envelope.
According to my Invention the envelope blank is cut out, the parts united to
form the envelope, and the latter is closed and secured (after the contents have been
inserted) in the following manner:-The two side folds, whatever may be the
intended form of the envelope, are of much the same form as those of ordinary bag
envelopes, but they are caused to interlock by cutting a vertical slit at a short
distance from the edge of each fold, that in the one fold extending from the bottom
edge up to about the middle of the fold, whilst that in the other fold extends from
this point up to the top edge of the fold. Two loose strips are thus left, the one at
the upper half of the one fold, and the other at the lower half of the other fold.
The folds are of such width as to overlap one another sufficiently to allow of the
two strips interlocking together, so that a portion of each fold is underneath a
portion of the other fold, and cannot be separated without unfastening the ends of
the strips, which are securely fastened, the one by an eyelet, and the other by
gumming, as hereafter described, in addition to the overlapping portions of the folds
being gummed or otherwise united.

page_text: The bottom flap falls down over the side folds in the usual manner, and has
lateral extensions which are folded round the lower corners of the envelope over on
to the front side thereof, where their ends overlap one another, the bottom flap and
its extensions being gummed down and still further secured by a metal eyelet passed
completely through the envelope from front to back, the said eyelet securing at once
the two side folds, the bottom flap, and its two lateral extensions.
At the upper part of the side folds there is what I térm a top inner flap, formed
by an upward extension of the two side folds; this flap is gummed, and when the
contents of the envelope are inserted is folded inwards and caused to adhere to the
inside surface of the envelope front, thus closing the mouth of the envelope and
securing the end of the interlocking strip of the one fold, the other having been
secured by the eyelet above mentioned.
The envelope is further provided with a top flap, which is folded down and
secured by gum in the ordinary way, and has two tongues that are passed through
slots in the side folds into the interior of the envelope, to which, as well as to the
contents if desired, the said tongues are caused to adhere, the tongues being for this
purpose gummed on one or both sides.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alfred Mackrill in the Great Seal Patent Office on the 31st January
1878.
ALFRED MACKRILL, of Whitefriars Street, in the City of London. "IMPROVE-
MENTS IN ENVELOPES."
My Invention relates more particularly to envelopes intended for the transmission
of registered letters, bank notes, and other valuables or documents by post, and it
consists in so interlocking and otherwise securing the various folds or flaps of the
envelope together that the contents cannot be surreptitiously abstracted without
destroying or at least disfiguring the envelope to such an extent as to ensure
immediate detection by the most casual observer.
According to my Invention the envelope blank is cut out, the parts united to
form the envelope, and the latter is closed and sealed (after the contents have been
inserted) in the following manner :-The two side folds or flaps, whatever may be
the intended form of the envelope, are of much the same form as those of ordinary
bag envelopes, but they are interlocked or halved together by cutting a vertical slit
at a short distance from the edge of each fold, extending in the one from the bottom
edge up to about the middle, and in the other from this point up to the top edge.
Two loose strips are thus left, the one at the upper half of the one fold, and the
other at the lower half of the other fold. The folds are of such width as to overlap
one another sufficiently to allow of the two strips being so interlocked that a portion
of each fold is overlapped by a portion of the other fold, and the two folds or flaps
cannot be separated without unfastening the ends of the strips, which are firmly
secured, the one by an eyelet, and the other by being turned in and gummed to the
inside of the envelope, as hereafter described, besides which the whole of the over-
lapping portions of the folds are gummed together or otherwise united.
The bottom flap folds down over the side folds in the usual manner, and has
lateral extensions which are folded round on to the front side of the envelope, where

page_text: their ends overlap one another, the bottom flap and its extensions being gummed
down and still further secured by a metal eyelet passed completely through the
envelope from front to back, the said eyelet securing at once the two side folds, the
bottom flap, and its two lateral extensions.
At the upper part of the side folds there is what I term an inner top flap, formed
by an upward extension of the two side folds; this flap gummed, and when the
contents of the envelope are inserted is folded inwards and caused to adhere to the
inside surface of the envelope front, thus closing the mouth of the envelope and
securing the end of the interlocking strip of the one fold, the other having been
secured by the eyelet above mentioned.
The outer top flap of the envelope is folded down and secured by gum in the
ordinary way, and has two tongues that are passed through slits in the side folds into
the interior of the envelope, to which, as well as to the contents if desired, the said
tongues are caused to adhere, the tongues being for this purpose gummed on one or
both sides.
Figure 1 represents the envelope blank as cut out from the sheet of paper or
other material.
Figures 2, 3, 4, and 5 show the successive stages in the operation of making the
envelope.
Figure 6 shows the envelope closed and secured.
It will be seen by Figure 1 that the blank may be cut out from a rectangular
sheet of paper with comparatively little waste, nearly the whole of the sheet being
utilised, which is an important advantage.
A is the front; B, B₁, are the side flaps or folds; C is the bottom flap; D is the
outer top flap; and E the inner top flap.
The blank is cut out and the various slits are made therein, as shown in Figure 1,
at one operation by a knife of corresponding form in a press of the ordinary or any
other suitable construction. The side flaps B, B', are of such width as to overlap
one another about an inch, more or less, and slits 1, 1, are made in these flaps
parallel with their edges, and at a distance therefrom equal to half the amount by
which the flaps B, B, overlap each other. The slit in flap B extends from the
bottom up to about the middle of its height, and the slit in flap B¹ extends from a
corresponding height to the top of the flap, so as to leave two loose strips b, b',
attached to the side flaps B, B¹. c, c¹, are strips or lateral extensions of the bottom
flap C, cut off from the bottom of the side flaps B, B', by the slits 2, 2. 3, 3, are
slits through which the tabs d, d, of the outer top flap are passed when the envelope
is closed and secured.
The blank having been cut out and creased at the folds, as in Figure 1, is then
folded, and the side flaps interlocked by passing the strips b, b1, behind one another,
so that each flap overlaps the other, as shewn in Figure 2. These strips b, b, and
the other portions of the flaps B, B', are them gumined or pasted down, and the
bottom flap C is then turned up and gummed or pasted down, as shewn in Figure 3.
The side strips or extensions c, c', are then folded round on to the front of the
envelope, and also gummed or pasted down, and an eyelet f is finally passed through
the whole, vizt, the overlapping ends of these strips c, c¹, the front A, the side flap B',
the strip b of the other side flap B, and the bottom flap C, and clenched, thus
securely fastening the bottom end of the envelope.
The inner top flap E, formed by the extension at the upper ends of the side flaps,
is gummed on its outer surface, and the top flap D is gummed on the whole of its
inner surface, and on the outer surface of the tabs d, as indicated by the cross hatch
lines, for the purpose of securing the mouth of the envelope by turning in the flap E
and sticking it to the opposite inner surface of the front A, and by turning down
the flap D, sticking it to the flaps B, B', passing the tabs d, d, through the slits 3, 3,

page_text: and sticking them to the inside surface of the front A, and also to the contents if
desired.
Having described the nature of my Invention, and the manner of performing the
same, I declare that what I claim as my Invention to be protected by the herein-
before in part recited Letters Patent is,-
First. The improved envelope, substantially as herein shewn and described.
Second. An envelope in which the two side folds or flaps are interlocked or halved,
so that the edge of each fold or flap overlaps the other fold or flap, substantially as
shown and described.
Third. An envelope in which lateral extensions of the bottom flap are folded
round on to the front of the envelope, and their overlapping ends secured by an
eyelet passing through from front to back, substantially as shown and described.
Fourth. The combination in an envelope with the side folds or flaps interlocked
or halved together, as above specified, of the inner top flap (formed by extensions of
the side flaps) intended to be folded in and attached to the inside of the envelope
for the purpose of securing the connection of the side flaps at the top of the envelope,
substantially as set forth.
Fifth. The combination in an envelope of the side flaps interlocked or halved
together, as described, and the lateral extensions of the bottom flap secured by an
eyelet, which also secures the connection of the side flaps at the bottom of the
envelope, substantially as shown and described.
In witness whereof, I, the said Alfred Mackrill, have hereunto set my hand
and seal, this Thirtieth day of January, in the year of our Lord One
thousand eight hundred and seventy-eight.
.lZDIIIו נז!