IMPROVEMENTS IN THE MANUFACTURE OF UMBRELLA FABRICS
Year: 1874

page_text: PROVISIONAL SPECIFICATION left by William Thomas at the Office
of the Commissioners of Patents, with his Petition, on the 29th
September 1874:
I, WILLIAM THOMAS, of No. 128, Cheapside, in the City of London,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
THE MANUFACTURE OF UMBRELLA FABRICS," to be as follows:-
This Invention relates to the manufacture of fabric for umbrellas, such
fabric having portions strengthened where it is subjected to the greatest
wear, and being woven in such a manner that it can be cut without
waste into pieces of the triangular form required.
Each of the segments of which an umbrella fabric consists, usually
eight in number, is of the form of an isosceles triangle, the sides of which
are stitched to the sides of those adjoining to it along each of the ribs
of the umbrella. When the umbrella is folded up the parts of the fabric
most exposed to wear are those which form the vertices of the several
segments and those which constitute the edges of each fold, namely, the
portion in each segment at or near the line from the vertex which
bisects the triangle. In order to strengthen these parts so as to render

page_text: them as durable as the less exposed parts of the fabric, I introduce in
the web of fabric which is to be cut into the segments lines of stronger
or additional warp at those parts which, on the web being cut, will
form the middle portions of the triangles, such lines of strengthened or
additional warp running in a straight direction along the web. As in
cutting a web woven in this manner, if its sides were straight and
parallel, there would be a waste of the half triangular segment at each
side of the web in each, length cut, I weave the web so as to avoid such
waste as I will now explain according to two methods.
One method is to weave the fabric in the form of a continuous cylinder
having lines of strengthened warp parallel to the axis, which cylinder
after it is woven is cut into the required lengths, and each of these
lengths is then cut into triangular segments along lines inclined at the
required angle to the axis of the cylinder, that is to say, diagonally from
the extremity of each strengthened warp to the opposite extremity of the 1
next. For weaving the fabric thus in cylindrical form any known
circular loom may be employed, the warp threads being extended in a
radial direction from bobbins mounted round the circumference of the
loom framing towards the centre thereof, and the shuttle being caused
to travel circularly between these threads, which are alternately raised :
and lowered for the passage of the shuttle over and under them.
Another method of weaving the fabric so as to avoid waste is to weave
it as a flat web with borders, which are not straight and parallel to the
lines of warp, but of a zig-zag form, inclined inwards and outwards
alternately to suit the shape of the triangles, which have to be cut from
it. If the fabric were woven in this form by merely omitting to work
in those portions of the border warps which would extend across the
indentations or gaps of the zig-zags there would be a considerable waste
of warp.
In order to avoid this waste I proceed in the following manner :—
I will suppose that a weft has been shot across the widest part of the
fabric, and that the harness is arranged so as to drop thread after thread
of warp on either side, whereby the web becomes gradually more and
more narrowed, until after a certain length has been woven, its width is
reduced by the amount required, a number of the warp threads along
each border being thus free from the gradually narrowed web. The
harness then begins to take up these threads one after another so as
gradually to widen the fabric, but while it is doing so the portion now

page_text: being woven, instead of being wound continuously on a roller is gathered
gradually up into a plait along with the portion previously woven, so
that each of the border warp threads at or near the point where it
became freed from the previously woven portion is worked into the new
portion of web. When the plait is completed the warp threads joining
its edges arc cut, and the fabric is spread out as a web of the zig-zag
outline required, without the waste of those portions of the border warp
threads which are not required in the indented parts of the outline.
It
may be readily understood that instead of working the harness by
cards for weaving in this manner, it may be worked by cams of fixed
form and setting, so as to repeat the same outline throughout the web or
throughout a succession of webs.