In this weave the working of the warp is the same as in taffeta, except
that instead of one pick, two or more are inserted in the same shed. It is
mostly used in selvedges, where it serves to give more firmness to the edge
of an otherwise loosely woven cloth, and prevents the weaving ahead of the
edge in a tight weave. Gros de Tours is sometimes used, especially when
cotton or wool filling is employed, with a view to lay two picks nicely
side by side, whereas a thread entered two ply with the taffeta weave will
always receive some twist, which may disturb the perfect evenness of the
fabric.

Fig. 18 is a Gros de Tours with two picks on four harness straight through.

Fig. 19 illustrates this weave with three picks drawn end and end on two
sections of four shafts each.

* * * * *

[Page 20]
SERGE or TWILL WEAVES

While the taffeta weave produces either an entirely smooth fabric, or one
with a distinct transverse rib as in gros-grain, the twill weave forms
diagonal lines on the cloth, running either from left to right or from
right to left.

To make a twill, not less than three ends and three picks are required, of
which each thread floats over two of the other system and interlaces with
the third. The rotation of the interlacing is always consecutive, that is
it moves with each succeeding pick one thread to the right (or to the left
if the lines are to run in that direction). If warp and filling have the