at many fabrics that have a selvedge--the warp must be parallel to
the selvedge.

In fabrics that have been fulled, raised, and cropped, as buckskin,
flannel, etc., the direction of the nap will indicate the direction of
the warp, since the nap runs in this direction.

In the case of fabrics with doubled and single threads, the doubled
threads are always found in the warp.

In fabrics composed of cotton and woolen threads running in different
directions, the cotton yarn usually forms the warp and the woolen yarn
the filling. Then again the warp threads of all fabrics are more
tightly twisted than the filling threads, and are separated at more
regular intervals.

Sometimes in stiffened or starched goods threads running in only one
direction can be seen. In this case they are the warp threads.

If one set of threads appears stiffer and straighter than the other,
the former may be regarded as warp, while the rough and crooked
threads are the filling. The yarn also gives one a hint, since the
better, longer, and higher number material constitutes the warp, while
the thicker yarn the filling.

The direction of the twist of the thread is conclusive; if one set has
a strong right twist and the other a left twist the first is the warp.

After determining the direction of the warp and filling, the next
point is to determine the interlacing of the warp and filling
threads--the weave. This may be done by inspection or by means of a
pick-glass and needle. The weave may be plotted on design paper
(plotting paper), the projecting warp threads being indicated by
filling up the corresponding square, and leaving those referring to
the filling threads blank. In this way the weaving pattern of the
sample is obtained, and serves as a guide to the weaver in making the
fabric, as well as for the preparation of the pattern cards for the
Jacquard loom.

=Testing the Strength and Elasticity of a Fabric.= The old-fashioned
plan of testing cloth by tearing it by the hand is unreliable, because
tearing frequently requires only a certain skilled knack whereby the
best material can be pulled in two. In this way an experienced man may
tell good from bad cloth, but he cannot determine slight differences
in quality, because he has exerted his strength so often that his
capacity to distinguish the actual force has disappeared.

The best means of determining the strength of a fabric is by means of
a mechanical dynamometer,[19] which expresses