An Improvement in Envelopes.
Year: 1892

page_text: COMPLETE SPECIFICATION.
An Improvement in Envelopes.
I, THOMAS DURRANS, of 44, Upper Baker Street, London, Architect, do
hereby declare the nature of the said invention and in what manner the same is to
be performed, to be particularly described and ascertained in and by the following
statement :-
This invention relates to an improvement in the formation of envelopes intended
for use for enclosing book-post matters and required to be left unsealed for
inspection of the contents by the postal authorities; the improvement being
designed to enable the envelope to be closed in such a manner as to effectually
secure the contents and as to prevent other postal missives from entering the
envelope, and to facilitate the closing and opening thereof by the sender and
receiver respectively, as well as by the postal authorities to make any necessary
examination of the contents.
In carrying out the invention, I prefer to apply the improvement to envelopes of
the improved formation described in the Specification of Letters Patent No. 10828
of 1889 granted to me, as envelopes of such improved formation (with the closing
flap ungummed) offer peculiar facilities for the application of the present
improvement, and enable the utmost advantages to be attained.
Examples of such envelopes as adapted with the present improvement, are
represented on the accompanying drawings; on which:-
Fig. 1, represents one of the improved envelopes fully opened ready for the
reception of postal matter.
Fig. 2, represents the operation of closing the envelope.
Fig. 3, represents the closed envelope.
Figs. 4 to 6, represent like views to Fig. 3, of modifications.
Like reference numerals or letters indicate like parts wherever they are repeated
on the accompanying drawings.
The invention consists, mainly, (referring to Figs. 1 to 3,) in forming one end of
the closing flap 5, of the envelope with a locking part 6, adapted to engage with
the adjacent end of a slit 7, made in the under side lappet 8, so as to hold the parts
together in the manner represented in Fig. 3.
The locking part 6, is made by recessing the under edge of the closing flap in
such a manner as to leave an angular or rounded projecting part a, nearer the
corner b, of such edge of the flap than is the bottom point c, of the recess, so as to
necessitate a slight angular movement of the closing flap in the manner represented
in Fig. 2. or a slight bending of the envelope to cause the projecting part a, to
clear and pass the locking end of the slit 7.
The exact formation of the locking part 6, is immaterial so long as it possesses
the characteristics enabling it to engage with the slit 7, or its equivalent in the
manner described.
The disposition of the slit 7, may also be variously modified so long as it agrees
with that of the locking part of the closing flap; as may also its formation, as, for
instance, it may be of a curvilinear (vide Fig. 1.) or rectilinear (vide Fig. 3.) of a
convex (vide Fig. 2) or concave formation relatively to the locking end of the
closing flap.
prefer to arrange the locking end of the slit 7, adjacent to the double thickness
of paper or other material formed by the overlapping of the side lappet 8, by the
under lappet 9, so as to obtain the most secure holding of the flap and the least
likelihood of the locking end of the slit being torn.
I can, however, if required, strengthen the part of the lappet 8, through which

page_text: the slit is made, by sufficiently extending either the opposite lappet 10, or the under
lappet 9, and cutting the slit 7, through both thicknesses.
can, also, if the envelope is required to contain comparatively bulky articles
likely to cause a strain on the locking part of the closing flap, apply to the lower
or end edge or to the free corner of the flap an adherent strengthening strip of
paper or other material in which the locking part will also be made. Or such
locking part may be made in a strip of the same or of a different substance, say,
canvas or linen, and applied to the lower or end edge or to the free corner of the
closing flap, the latter being otherwise made plain in an ordinary manner.
I can, also, make the envelope with two or more slits 7, and with correspondingly
disposed locking parts 6.
As a modification of the foregoing, I can substitute for the slit, a pocket made
by extending the bottom lappet 9, across the side lappet 8, and leaving its top edge
adjacent to the locking part of the closing flap ungummed, vide Fig. 4, so as to
form a pocket adapted to receive the end of the closing flap, the locking part 6, of
which will engage with the adjacent edge of the opposite side flap 10, but this
modification is not so advantageous as the arrangements embodying the slit 7,
described with reference to the other figs. of the drawings, as it requires a greater
amount of paper in the formation of the envelope.
As a further modification, either when using the slit or the pocket, I can apply
the locking part 6, at the free end of the closing flap, vide Fig. 5, in lieu of at its
under side as represented in Figs. 1 to 4, so as to engage with the opposite or outer
end of the slit or pocket, or I can make the locking part 6, of the closing flap of a
double locking formation at the free corners of the closing flap vide Fig. 6, so as to
engage with both ends of the slit or pocket.
In any of the foregoing arrangements, the closing flap may be made either right-
handed or left-handed at the side or at the end of the envelope, the said
lappets 8-9-10 being correspondingly arranged.
Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed, I declare that what
I claim is :-
1. The formation of envelopes with a locking closing flap and a corresponding
locking slit formed in one of the lappets, as hereinbefore described with reference
to Figs. 1 to 3, of the accompanying drawings.
2. The formation of envelopes with a locking closing flap and a corresponding
locking pocket formed between two of the lappets, as hereinbefore described with
reference to Fig. 4, of the drawings.
3. The modifications of the invention hereinbefore described with reference to
Figs. 5 and 6, of the drawings.
4. In envelopes, in combination, a closing flap and a slit lappet or overlapping
lappets or pocketted lappets adapted to co-act in the improved manner hereinbefore
described.
5. The formation of envelopes with a closing flap substantially of the peculiar
formation or formations hereinbefore described with reference to the accompanying
drawings.
6. The several other variations or modifications of the invention hereinbefore
described.
Dated this 29th day of Sentember 1892
DAY, DAVIES & HUNT,
321, High Holborn, London, W.C., Agents for the Applicant.