IMPROVEMENTS IN SEWING MACHINES
Year: 1868

page_text: PROVISIONAL SPECIFICATION left by Allen Booth and John Harrison
at the Office of the Commissioners of Patents, with their Petition,
on the 23rd September 1868.
We, ALLEN BOOTH, of Staleybridge, in the County of Lancaster, and
JOHN HARRISON, of the same Place, Bootmakers, do hereby declare the
nature of the said Invention for "IMPROVEMENTS IN SEWING MACHINES," to
be as follows:-
This Invention relates, firstly, to improvements in sewing machines
for the purpose of supplying the under thread in greater quantity than
has hitherto been practicable in order that the machine may work longer
before requiring such under thread to be replenished, and consists in
substituting a reel or bobbin carrying the under thread in place of the
shuttles or spools hitherto used for the purpose, and such reel or bobbin
is disposed in a cylindrical box or cavity formed in the table or arm of
the machine parallel with the vertical needle bar, and is placed upon a
stationary circular table at the bottom of such box or cavity. A disc
works underneath and concentrically with such circular table, and has
a double hook or looper upon its periphery, which rises vertically above
the edge of the table so as to revolve quite round the reel or bobbin

page_text: carrying the under thread, the necessary motion being imparted to such
hook or looper by a toothed pinion upon the shank or sleeve of the disc
being geared into a rack, which is moved backwards and forwards by a
cam. The hook or looper herein-before mentioned is for the purpose of
carrying the top thread over, under, and round the bobbin or reel so as
to be equivalent to passing such reel or bobbin through the loop so
formed on the under side of the fabric, and thus to produce a complete
lock stitch, the loose thread being gathered up at every stitch by means
of a "taker-up" consisting of a series of pullys or friction bowls.
working at the top of the trunk and needle bar.
Secondly, these improvements relate to a novel description of feed
motion which is arranged to work in any direction, and consists of a
sleeve surrounding a cylindrical bar through which the needle bar
reciprocates, and the leg of the foot is depressed in a slot formed in such
sleeve, and turns with it according to the direction in which it is neces-
sary to work, which is adjustable by a tooth formed upon the end of a
pressure spring taking into one of a series of teeth formed round the
sleeve, and thus such pressure spring serves the double purpose of
fixing the direction in which the feed motion shall work, and also
applies the necessary pressure to the foot, which pressure is taken off
at the proper time by a collar moved up and down by a lever geared to
a cam, and the necessary motion is imparted to the foot by a collar sur-
rounding the sleeve, and worked up and down by a lever geared to a
cam, the length of the feed bar being regulated by an adjusting screw in
the leg of the foot.
Thirdley, these improvements relate to a novel description of tension
for the threads used in sewing machines, and consists in applying the
pressure of a (by preference) three-legged spring to a sleeve upon which
the bobbin is fixed, so that as such sleeve is pressed up against a collar by
means of the three-legged spring a regular degree of tension is obtained,
which can be regulated by a nut and washer screwed up against the
spring.