ople of the world have
always used wool for their clothing. Wool is the soft, curly covering
which forms the fleecy coat of the sheep and similar animals, such as
the goat and alpaca. Wool fiber when viewed under the microscope is
seen to consist roughly of three parts:

1st. Epidermis, or outer surface, which is a series of scales lying
one upon the other.

2d. Cortex, or intermediate substance, consisting of angular,
elongated cells, which give strength to the wool.

3d. Medulla, or pith of the fiber.

[Illustration: WOOL FIBER

Highly magnified]

=Difference between Wool and Hair.= Not all animal fibers are alike.
They vary in fineness, softness, length, and strength, from the finest
Merino wool to the rigid bristles of the wild boar. At just what point
it can be said that the animal fiber ceases to be wool and becomes
hair, is difficult to determine, because there is a gradual and
imperceptible gradation from wool to hair.[1] The distinction between
wool and hair lies chiefly in the great fineness, softness, and wavy
delicacy of the woolen fiber, combined with its highly serrated
surface--upon which the luster of the wool depends.

=Characteristics of Wool.= The chief characteristic of wool is its
felting or shrinking power. This felting property from which wool
derives much of its value, and which is its special distinction from
hair, depends in part upon the kinks in the fiber, but mainly upon
the scales with which the fiber is covered. These scales or points
are exceedingly minute, ranging from about 1,100 to the inch to nearly
3,000. The stem of the fiber itself is extremely slender, being less
than one thousandth of an inch in diameter. In good felting wools the
scales are more perfect and numerous, while inferior wools generally
possess fewer serrations, and are less perfect in structure.

In the process of felting the fibers become entangled with one
another, and the little projecting scales hook into one another and
hold the fibers closely interlocked. The deeper these scales fit into
one another the closer becomes the structure of the thread.

=Classification of Wool.= The various kinds of wool used in commerce
are named either from the breed of the sheep or from the country or
locality in which the sheep are reared. Thus we get Merino wool from
Merino sheep, while English, American, and Australian wools are named
from the respective countries. As the result of cross breeding of
different sheep