Improvements in Self-adjusting Expansible Envelopes.
Year: 1897

page_text: Date of Application, 23rd Feb., 1897-Accepted, 24th Apr., 1897
COMPLETE SPECIFICATION.
Improvements in Self-adjusting Expansible Envelopes.
I, WILLIAM DEXTER BRADSTREET, of No. 33 Newton Street, in the City of
Waltham, County of Middlesex and State of Massachusetts, United States of America,
Banker, do hereby declare the nature of this invention, and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement :-
My invention has for its object to provide a self-adjusting envelope of simple
construction which is capable of being expanded within certain limits to increase its
capacity; and to this end my invention consists in an envelope having two adjoining
flaps fastened together by means of a sliding connection which permits the envelope
to expand and adjust itself to the thickness of the papers or articles placed therein, as
hereinafter more fully set forth.
In the accompanying drawings:
Figure 1 is a perspective view of an envelope constructed in accordance with my
invention.
Figure 2 is a perspective view of the same, expanded to increase its capacity.
Figure 3 is a section on the line 3-3 of Figure 2.
Figure 4 is an enlarged sectional detail on the line 4-4 of Figure 1.
C
In the said drawings, A represents an envelope preferably composed of strong and
stiff material, such as thick paper or paper having a cloth lining, to adapt it for use
in filing away documents or papers or containing bulky articles. b, b, represent the
end or side flaps, the lower flap or back, and d the upper or closing flap which may
be provided, if desired, with a tape or other suitable fastening device for holding it in
place when folded over to close the envelope. Each of the end flaps is adjustably
secured to the lower flap e by means of an eyelet or flanged rivet which slides in a
slot or track formed in the underlying portion of the lower flap, the inner flange
of the eyelet lapping the edges of the slot g, whereby the end flaps are held securely
to the lower flap while sliding thereupon, the ends of said slots forming stops to limit
the movement of the eyelets or rivets therein. By means of the sliding connections
above described, it will be seen that the envelope is rendered self-adjusting so that it
will expand, as shown in Figure 2, to any desired degree within the limits of the
slots g, for the reception of bulky papers or other articles which it may be desired
to place within it, thus especially adapting it for filing away documents, as it will lie
comparatively flat when a few papers only are placed within it, and as more papers
are added, the end flaps will automatically slide back on the lower flap to proportionately
increase its capacity, while as papers are withdrawn, the thickness of the envelope
can be correspondingly diminished.
The top flap d is preferably made large and square to cover the contents of the
envelope when expanded. The end flaps may overlie or underlie the lower flap as
preferred, and each of the end flaps may be secured to the lower flap by two or
more sliding connections instead of one, for additional strength if desired. Instead
of both end flaps being adjustably secured to the lower flap as described, one only
of said flaps may be so secured, the other being rigidly fastened in place; I prefer
however to make both end flaps adjustable, as such construction increases the
expansibility of the envelope.
It is obvious that the construction of the sliding connections between the end
flaps and the lower flap may be varied, as any suitable fastening device which will

page_text: secure the end flap to the lower flap in such manner as to permit the one to
slide on the other, may be employed without departing from the spirit of my
invention.
Instead of connecting either or both of the end flaps with the lower flap c,
the two end flaps may be extended to lap one another and be adjustably secured
together by means of a suitable sliding connection which will permit the envelope to
expand in substantially the same manner as previously described.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. In an envelope, the combination with the lower flap or back, of an end flap
secured to the lower flap by a sliding fastening device, whereby the envelope is
made expansible to vary its capacity, said fastening device being provided with a
stop to limit the expansibility of the envelope, substantially as described.
2. A self-adjusting expansible envelope having an end flap adjustably secured to
the lower flap or back by means of a rivet or projection on the one part and a
slot or track on the other part, whereby the two connected parts are permitted to
slide the one upon the other to vary the capacity of the envelope, substantially as
described.
Datal th: 09-1 1...
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HASELTINE, LAKE & Co.,
45 Southampton Buildings, W.C., Agents for the Applicant.