An invention so important to the agricultural interests of the country could not long remain a secret. The knowledge of it swept through the State, and so great was the excitement on the subject that crowds of persons came from all parts to see the machine; it was not deemed safe to gratify curiosity until the patent-right should be secured. But so determined were some of these people that neither law nor justice could restrain them; they broke into the building by night and carried off the machine. In this way the public became possessed of the invention, and before Whitney could complete his model and secure his patent, a number of machines, patterned after his, were in successful operation. The principle of the Whitney cotton-gin and all other gins following its features is so well known as to make it scarcely worth while to describe it here. The different parts are two cylinders of different diameters, mounted in a strong wooden frame, one cylinder bearing a number of circular saws fitted into grooves cut into the cylinder. The other hollow cylinder is mounted with brushes, the tips of whose bristles touch the saw-teeth. The cotton is put into a hopper, where it is met by the sharp teeth of the saws, torn from the seed, and carried to a point where the brushes sweep it off into a convenient receptacle. The seeds are too large to pass between the bars through which the saws protrude. This is the principle of the first machine, but many improvements have been made since Whitney's day. Nevertheless, by means of the cotton-gin, even in its earliest shape, one man, with the aid of two-horse power, could clean five thousand pounds of cotton in a day. [Illustration: The Cotton-Gin. (From the original model.)]