are moved forward on screws in the direction of the other set of
rollers, and the pins in the gills always keep the fiber perfectly
straight. The second set of rollers is termed the draught rollers,
since by them the wool, after passing through the front rollers, is
drawn out and reduced in thickness. This is accomplished because the
second rollers revolve at a higher rate of speed than the first
rollers, the speed being regulated according to the length of the
wool, and the thickness of the yarn to be produced. These gills are
used in the production of worsted yarn until the size of the rope of
wool has been so reduced and twisted that there is no chance of any
fiber getting crossed or out of the order of straightness. A worsted
yarn is, consequently, a straight yarn, or a yarn produced from
perfectly straight fibers.

[Illustration: GILLING

1. Cans containing Comb Ends or Sliver.
2. Balling Head.
3. Stock from Balling Head No. 2.
4. Screws for applying pressure to Back Rollers.
5. Screws for applying pressure to Front Rollers.
6. Faller Screws situated between No. 4 and No. 5.
7. Guard for covering gears which drive Back Rollers.
8. Guard covering gears which drive Balling Head.
9. Balling Head.]

The combing of wool may be dispensed with in some cases, although
such a yarn is not in common use. When combing is dispensed with, the
gills, in connection with the draught of the rollers, make the fibers
straight, and produce a worsted yarn, although such a yarn has a
tendency to be uneven and knotty.

Before the wool can be spun it must be made into roving of a suitable
thickness. This is done by passing it, after being combed, through a
series of operations termed drawing, whose functions are to produce a
gradual reduction in thickness at each stage. Although the number of
machines varies according to the kind of wool to be treated, still the
same principle applies to all.

=Spinning.= The process of spinning is the last in the formation of
yarn or thread, the subsequent operations having for their object the
strengthening of the yarn by combining two or more strands and
afterward arranging them for weaving or for the purpose for which the
yarn is required. It is also the last time that the fibers are
mechanically drawn over each other or drafted, and this is invariably
done from a single roving. The humidity and temperature of the
spinning room must be adjusted to conditions. Each spinner is