An Improved Camp or Folding Chair.
Year: 1893

page_text: Date of Application, 8th June, 1893
Complete Specification Left, 16th Aug., 1893-Accepted, 16th Sept., 1893
PROVISIONAL SPECIFICATION.
An Improved Camp or Folding Chair.
I, JAMES RICHARD BELL, Superintending Engineer Public Works Department,
India, at present residing at 55 Gloucester Street, Warwick Square, London in
the County of London, do hereby declare the nature of this invention to be as
follows:-
This invention relates to an improved camp or folding chair to be called "Bell's
folding camp chair" of which the following is a description reference being had to
the accompanying drawing.
Figure 1 being a vertical section through a chair embodying my invention and
Figure 2 one of its fastenings detached.
The chair consists of five parts, viz. -1 the back frame, 2 the seat frame, 3 the
front frame, 4 the two arms or radius bars, and 5 two rule jointed locking bars.
1. The back frame consists of two back legs, prolonged upwards to form a back-
rest and connected crosswise by two or more cross bars at A and C exactly as in
any ordinary non-folding chair. The back-rest between A and C may be filled in
or pannelled with canework, upholstery or otherwise to suit the comfort of the
sitter, and for both comfort and stability it is well to curve the back-frame out-
wards as shewn. Though not essential it is desirable that one back cross bar should
stiffen this frame at or very near the point C. As in fixed chairs the back-frame
may diminish in width from A to the ground.
2. The seat-frame consisting of two side bars firmly connected by two cross bars,
is hinged at C to the back-frame in such fashion that it can be folded upwards till
it lies in parallel contact with the back-rest A. C. It is preferable but not essential
that the seat-frame should (as shewn) be so curved as to conform with the line of
the back-rest. When open the heel of the seat-frame abuts against the back-frame
so that the seat cannot turn downwards on its hinge at C below the normal position.
The seat like the back-rest should taper in width from back to front and must be
caned or upholstered in any usual fashion.
3. The front-frame consists of two front legs prolonged upwards, in the case of an
arm chair, to carry the usual arm rests; and the legs are connected or framed
together in any usual way, but preferably by a deep narrow cross bar attached as
shewn to the front legs on their outer faces. This frame is hinged or preferably
pivotted to the seat frame at E and when the chair is open the seat butts or rests on
the front cross bar and consequently the front frame in turning on the pivot E
cannot open beyond the normal open position. The width between the front legs
suffices to embrace the seat frame between them and it is desirable to curve the
front legs in elevation to conform at once with the curve of the seat and that of the
back.
4. The arm-rests are pivotted at once to the back-frame on the outsides at B and
flush with the upward extensions of the front legs at D by in this case hinges.
The front end of the arm and the top of the arm support are so mitred (preferably
by a dove-tailed mitre) that in the open position of the chair they form a neat joint
that cannot open beyond the normal position. The geometrical figure inclosed by
the pivot points B. C. E. D. is a quadrilateral but neither necessarily nor preferably
a parallelogram for by making B. C. higher than D. E. the arm assumes a more
comfortable slope and also the foot of the front leg is thrown more forward and
increases the stability of the chair. The absolutely necessary geometrical
conditions of the quadrilateral B. C. E. D. are that C B + BD ČE + ED

page_text: Where an armless chair is required the arms above the seat level are replaced by
side radius bars as shewn in dotted lines and the extensions of the front legs above
the seat level are in this case omitted. The conditions of the quadrilateral, quasi
parallel, motion in the armless arrangement are mutatis mutandis, the same as for
the arm chair.
Under the above described conditions the position of the parts when the chair is
closed brings the arms into the same plane as the back-rest,--the seat into parallel
contact with the back-rest,--the front legs into the same plane with the seat and
the front cross bar that connects the two front legs together, lies immediately
outside of the seat and serves to partly protect its underside from accidental
injuries. The folded chair has thus a curved outline which may appear inconvenient
for storage but the inconvenience is minimised where several similar chairs are
packed together and the curved form can, on the other hand, be advantageously
stowed or slung on pack animals.
5. Each rule jointed locking bar B. F. E is the exact length of the diagonal of
the quadrilateral B. C. E. D. and is pivotted on the same axis as the back frame
at B and the front frame at E. The locking bar has a rule-joint at F that allows
it to be doubled on itself when the pivot point F is pulled upwards. Consequently
when the chair is being opened and the locking bar has come into a nearly straight
line, a push in an inward and downward direction locks it so that the chair cannot
be closed till after the locking bar has first been flexed upwards. The action here
is in fact identical with that of the struts of a buggy-hood. The position of the
pivot-point F in reference to B and E is dependent upon the proportions of the
quadrilateral B. C. E. D. and the essential equation for determining the ratio
of B F to F. E. is C B + B. F. =CE+EF.
=
6. The use of the locking bars is only essential where the chair has to be
frequently opened and closed, for owing to the arrangements by which the joints
at C. E. and D. can only turn in one specified direction it cannot possibly close
under the occupant's weight and it actually suffices for a chair that is not often
closed for transport to make all the joints at B. C. E. and D. sufficiently stiff to
require force to close them. Where often used stiff joints tend to work slack and,
in the modification of the invention where the locking bars are dispensed with, it is
best to fit the pivots with screws and nuts which should be tightened when the
chair is brought into use.
7. To avoid in this case the necessity of keeping a special wrench or screw driver
for tightening up the chair the screw head, or the nut, or both, are for the purpose
of this invention formed, as shewn in Figure 2 of the drawing with one or more
kerfs so shaped that any ordinary coin such as a shilling can be utilized as its screw
driver, converting it for the time being into a thumb nut. The objection to using
a fly or thumb nut in this connection lies in the risk of such a nut's wings entangling
the clothing of persons using the chair.
Dated this Eighth day of June 1893
COMPLETE SPECIFICATION.
An Improved Camp or Folding Chair.
1, JAMES RICHARD BELL, Superintending Engineer, Public Works Department,
India, at present residing at 55 Gloucester Street, Warwick Square, London, in
the County of London, do hereby declare the nature of this invention and in what 5
manner the same is to be performed, to be particularly described and ascertained in
and by the following statement :-
My invention relates to an improved camp or folding chair, and the objects of my
improvements are:-First, to provide a portable folding-chair. Second, to afford

page_text: facilities for securing the same in position when in use. Third, to facilitate the
packing of the same for transport or shipment.
I attain these objects by the construction illustrated on the accompanying drawing
on which
Figure 1 is a vertical section through a chair embodying my invention, and
Figure 2 a section and front view of a device or nut for stiffening the pivotted
joints.
The chair consists of five parts: - the back frame, 2 the seat frame, 3 the front
frame, 4 the two arms or radius bars, and 5 two rule-jointed locking bars.
The back frame 1 cousists of two legs A prolonged upwards to form a back rest,
and connected cross-wise by two or more bars B and C. The back rest between B
and C may be filled in or panelled with cane-work, upholstering, or otherwise to
suit the comfort of the sitter, and the frame may be made to diminish in width
from B to the ground. The seat frama 2, which may be caned or upholstered in
any desired manner consists of two side bars firmly connected by two cross-bars DE
hinged at F to the back frame 1 in such a manner that it can be folded upwards
till it lies in parallel contact with the back rest C. B, and for this purpose is
preferably made of a corresponding form to that of the back rest. It may also be
tapered from back to front. When open the heel of this seat frame 2, abuts
against the back frame 1, so that the seat cannot turn downward on its hinges at F
below the normal position.
The front frame 3 consists of two front legs G prolonged upwards in the case of
an arm chair to carry the usual arm rests 4, and the legs are connected or framed
together in any usual way, but preferably by a deep narrow cross-bar H attached
to the front legs G on their outer faces. This frame is hinged or pivotted to the
seat frame 2, at I in such a manner that when the chair is open, the seat butts or
rests on the front cross bar H, and the front frame 3 in turning on the pivot I, is thereby
prevented from opening beyond the necessary extent. The legs G are arranged at
a suitable distance apart to embrace the seat frame 2, and may be curved in
clevation to conform to the curve of the seat and that of the back.
The arm rests 4, are pivotted outside to the back frame 1, at K, and hinged to the
front legs at L. The front end of the arm and the top of the arm'support may be
pivotted together by a tenon-joint.
The rule-jointed locking bars 5, are the exact length of the diagonal of the
quadrilateral F KL I, and are pivotted on or near the same axes as the arms 4 at K,
and the front frame at I. Each bar has a rule joint at M which permits it to be
doubled on itself when the rule joint M is pulled upwards. By this arrangement
on the chair being opened, pressure applied in an inward and downward direction
upon the bars 5, at once locks them in position and prevents the chair from being
closed until the joints M have been pulled upwards. This action is identical with
that of the struts of a buggy-hood.
The geometrical figure enclosed by the pivot joints FK LI is preferably an
irregular quadrilateral, and by arranging the vertical distance between the
pivots FK higher than that between IL, the arm 4, is raised at its inner or back
end to any desired angle or slope, and the foot of the front leg G thrown slightly
forward thereby increasing the stability of the chair. The necessary geometrical
conditions of the quadrilateral F K L I are that FK + KL = FI+I L. The
relative position of the pivot point M in reference to K and I is dependent upon
the proportions of the quadrilateral F K L 1, and the essential equation for
determining the ratio of KM to M I is F K + KM = FI + I M.
When an armless chair is required the arms 4, above the seat level, are replaced
by side radius bars 4°, and the locking bar 5 by the bar 5ª, as shewn in dotted lines,
and the extension of the front legs above the seat level is then omitted. The
conditions of the quadrilateral k FI and the locking bars 5 in this armless
arrangement are, mutatis mutandis, the same as for the arm chair, and the essential
equations are: (1) k F + FI = kl + 11. (2) k F + Fm = kl+lm. Under the
above first described conditions the position of the parts when the chair is closed

page_text: brings the arms 4, into the same plane as the back rest, the seat 2, into parallel
contact with the back rest, the front legs 3, into the same plane with the seat 2,
and the front cross bar H that connects the two front legs together lies immediately
outside of the seat 2 and serves to partly protect its underside from accidental
injuries, and a similar action occurs in folding the alternative arrangement. The
folded chair has in either case a slightly curved outline and may be advantageously
stowed or slung on pack animals.
The use of the locking bars is only necessary where the chair has to be
frequently opened and closed, for owing to the arrangements by which the joints
at FI and can only turn in one specified direction, the chair has no tendency to
close under the occupant's weight, and by making the joints sufficiently stiff the
locking bars may be omitted altogether. Or in lieu of depending upon the stiffness
of the joints. I may provide them with screws and nuts for tightening the same
from time to time. In this case I form the screw head or nut N of a shape shewn
in Figure 2 of the accompanying drawing, with the object that it can be readily
tightened up by the aid of a coin O inserted in the slot or slots P formed within
the same, and without the use of any special spanner or wrench, and at the same
time avoid the risk of injury to the dress of the occupant, as would arise with the
use of a fly-nut or similar contrivance.
The dotted locking bars 5, may be used in conjunction with the full line locking
bars 5 may be used in conjunction with the dotted radius bars 4ª.
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 a folding-chair, the back frame 1, the seat frame 2, the front frame 3, the
two hinged arms 4 (or radius bars 4) and the two locking bars 5, (or 5ª) with rule
joints combined and arranged for the purposes specified and substantially as
described.
2. In a folding-chair the locking bars or stays divided into two parts and
connected by rule joints.
3. In a folding chair, the back frame 1, the seat frame 2, the front frame 3, the
hinged arms 4 or radius bars 4" combined and arranged for the purposes specified
and substantially as described.
4. In a folding chair or other semi-portable apparatus the nut or screw-head N
having a slot or slots suitably formed for permitting the screw to be operated by a
coin or other similar piece of metal.
Dated this Sixteenth day of August 1893.