h the cotton is drawn and the seeds forced out in the process. An
improved form of the roller gin is at present used for cleaning the
long-staple Sea Island cotton. The saw gin, which works on an entirely
different principle, is the machine which, with its improvements and
modifications, has separated the seed from fiber almost exclusively
for one hundred years of American cotton growing. In this machine the
seed cotton is fed into a box, one side of which is formed of a
grating of metal strips set close together, leaving a narrow opening
from one-eighth to a quarter of an inch wide. Into these openings a
row or "gang" of thin circular saws project mounted upon a revolving
mandrel. The long, protruding teeth of the saws, whirling rapidly,
catch the fibers, and pull them away from the seeds. The latter, being
too large to pass through the openings of the grating, roll downward
and out of the machine. The lint, removed from the row of saws by a
revolving brush, passes between rollers and is delivered from the
machine in the form of a lap or bat.

This machine is responsible for much of the "nep" (or knots) found in
American cotton, which is caused when the machine is overcharged. The
Whitney gin will turn through more cotton than any other type of
machine, and will clean from 200 to 300 pounds per hour. When the
machine is running at high speed the tendency is to string and knot
the cotton.

[Illustration: COTTON GIN

The upper figure shows Whitney's invention. The lower figure shows a
later form.]

The working of the ordinary gin is as follows: The wagon loaded with
cotton is driven under a galvanized spout called the sucker, through
which there is a suction of air which draws the cotton into the gins.
In each of the gins there are seventy circular saws revolving on one
shaft. These saws are about one inch apart, and the teeth go through
the gin breast, much as if one were to put the teeth of one comb into
the teeth of another comb. This process takes the lint cotton off the
seed, and by the use of brushes the cotton goes into the lint flute,
into the condenser, and into the box, where it is revolved and made
into a bale. While the lint is going through this process, the seeds,
being heavier and smaller, draw to the bottom of the gins, fall into
an auger which is operated by a belt, and then are dropped into a
conveyor and carried to the seed pile or houses. The lint goes in one
direction and the seed in another.