INVENTION OF THE COTTON GIN
The agricultural condition of Georgia and its neighboring States at the time that Whitney arrived there was very poor. There was no market for their products. A splendid cotton, with fibers from 1⅜ to 2½ inches long, was growing on the islands along the coast, but this cotton could not be raised inland. The upland product, known as “green seed” cotton, had a fiber only half as long as the “Sea Island” cotton, but the principal drawback to its use was the difficulty of separating the fiber from the seed. It was a day’s work for one woman to separate a single pound of the “green seed” cotton fiber.
His attention having been brought to this matter, Whitney undertook to design a machine which would remove the fiber from the seed in a small fraction of the time required by hand labor. He was visiting at the time at the plantation of Mrs. Greene, widow of General Nathaniel Greene, of Revolutionary fame, and he set himself to the task with such limited materials and tools as he could find on the estate. In a couple of weeks he had built a model which contained all the essentials of the modern cotton gin, with which a single man could separate more cotton in a day than could be produced by hand in a whole season. This was in the winter of 1792. The effect of the invention was felt immediately. Cotton production had been falling off steadily. In 1791, 189,316 pounds of cotton had been exported. The next year there was a falling off to 138,328 pounds, but following the introduction of the cotton gin exports rose to 487,000 pounds in 1793, 1,681,000 in 1794, and 6,276,000 in 1795. Fifty years later the world production amounted to 1,169,600,000, nearly seven-eighths of which was contributed by the United States, and of this only a small amount was Sea Island cotton.
A cotton gin (Fig. 65) consists of a gang of circular saws (A), with forwardly pointed teeth which pass between the ribs of an inclined grating (B) that forms the floor of a chamber (C) known as a roll box. In this box is mounted a toothed roller (D). The cotton is fed into the box and the fibers are seized by the teeth of the saws and dragged through the grating while the seeds, being too large to pass through, are left behind and, rolling down the grating, drop into a hopper. The action of the saws is such as to impart a rolling motion to the mass of cotton, and hence to the roller in the roll box. This tends to drag the cotton into the roll box and bring fresh supplies to the saws. The fleece carried by the saw teeth is beaten off by a wheel (E) fitted with wire brushes. These brushes, traveling in the same direction as the saw teeth, but at a higher velocity, readily disengage the fibers from the teeth and create an air blast that blows the cotton fleece out of the gin.
FIG. 65—SECTIONAL VIEW OF A COTTON GIN