In Eastern countries, where cotton has been cultivated and manufactured for ages, the methods in use in remote districts, particularly in India, are still of the most primitive character. Pre viously to the occurrence of the American Civil War, which caused a great amount of attention to be directed to that country as a source of cotton supply, these methods were almost general. The first was simply hand-picking, the second wss by the foot-roller, and the third by the churka.
The foot-roller may be termed the first mechanical appliance for cleansing cotton. The operator procures a flat smooth stone, 1-2 ft. square, which is covered with a layer of seed cotton. An iron roller is next placed upon it, and worked backward and forward by the feet of the operator, who sits upon a stool while at work. As the Indian cottons are mostly of the smooth-seeded varieties, the lateral pressure exerted pushes the seed over the edge of the stone, leaving the clean cotton upon its surface. The product of a day's work by this method is 4-6 lb. It is altogether ineffective when applied to the green-seeded American varieties, the fibres adhering very tenaciously.
Previous to the introduction of European gins into India, the churka was the instrument most generally in use. It is a rude roller-gin, containing two rollers, fixed in upright posts borne in a rail at their base, and rendered firm by a cross-piece. Sometimes both rollers are of wood, some times the upper one is of iron. The Guzerat churka may be taken as the representative of this class of machines; the upper roller is of iron, in. in diameter, the lower, of wood, 2 in. in diameter. The rollers are not geared together, and there is n slight space left between them. When working, their surface velocities are not alike, the iron one revolving most quickly. The cotton is presented to the rollers, and the fibre is dragged from the seed, and carried to the other side, the seed being kept back until cleared, when it falls in front of the rollers. It is sometimes worked by one person, sometimes by two. The yield is 6-8 lb. of clean cotton a day for each person engaged. When the churha is in good repair, the quality of the work is very good, no violence being done to the fibre. But the machine is liable to frequent derangement, and consider
able wear and tear, owing to the rudeness of its construction.
Eli Whitney's saw-gin consists of a drum carrying a number of circular plates, the periphery of which is cut so as to form teeth, or rather hooks. The plates are 9-12 in. in diameter ; above the cylinder is placed an inclined grid, which forms the bottom of a box or hopper, into which the seed cotton is placed. The bars of this grid are set sufficiently close to prevent the passage of the seed. When working, the plates upon the cylinder pass between the bars of the grid, to the depth of about one-third of their diameter, and the teeth, laying hold of the fibre, drag it through • the bars, leaving the seed behind. The latter is subjected to this action as long as any fibre remains upon it ; when thoroughly stripped, it falls through a narrow slit in the bottom of the box, into a receptacle provided for it. The cotton, as it is drawn through the grid by the saws, is stripped from them by means of a swiftly revolving brush, which throws it through an aperture into another apartment, called the " lint-room." It will be obvious from this description, that the filaments of cotton, being thus torn from the seed, are liable to serious damage from this action. A great amount of skill has, therefore, been spent in the endeavour to make the saws as harmless as possible in their action, and to diminish the acuteness of the stroke, by which the fibre might be broken. The striking edges are therefore rounded, made perfectly smooth, and curved in such a form as to avoid any sudden jerk or pull after the teeth have laid hold of the fibre ; whilst the increasing drag is such as to strip the lint from the seed, as speedily as possible, with a minimum of violence. There are numerous varieties of the saw-gin, but the differences between them are only in points of detail.
The Macarthy gin, so named from the inventor, is constructed on a different principle, and is admirably suited for long-stapled cottons. It is also capable of doing good work with the short stapled varieties. The production from it is not equal in amount to that from the saw-gin, but the quality is far better.