MACHINES FOR PREPARING COTTON FOR SPINNING.
It is a characteristic feature of spinning by machinery that the process does not, as in spinning by hand, proceed in one operation from the simple fibres to the perfected thread, but that it first produces a strong ribbon-like semi-fabric, technically known as a "sliver," in which the fibres, freed from foreign substances, are arranged together in regular straight and parallel order. This semi-fabric is then gradually drawn out to the desired degree of fineness, and the requisite firmness is filially imparted to it by twisting. Hence, in considering the subject of spinning by machinery, the entire process may be divided into two operations: (1) the preparation of the sliver (ginning, opening, and carding) and (2) the conversion of the sliver by drawing and spinning into threads. The principal machines used for the first process are represented on Plates 35 and 36, and those employed for the second process are shown on Plates 37 and 38.
Ginning: Whitney primary operation in spinning cot ton by machinery is " giuning.;"—that is, the separating of the fibre from the seed. Figures 1 and 2 (pi. 35) show in vertical section two machines, termed "cotton-gins," which are used for this purpose. The principal fea ture of the so-called "saw-gin" (fig. 2) invented by Eli Whitney is a cyl inder (a) armed with circular saws, a roller-brush (b), and a grate (c, c) com posed of iron rods. This grate serves for the removal of the seeds, and is fastened below to the plate a', and, together with the plate, can be set in a suitable position in relation to the teeth of the saw-blades by means of the screw c, which enters into the cross-piece f. To permit the varying arrangements of the grate the rods of the latter are also connected above with a plate, which is secured by hinge-joints (g) to the upper cross-piece h. The hopper for the reception of the cotton is made up on the two sides by the walls of the frame, in front by the adjustable plate below by the grate, and in rear by the curved plate 1. The plate i can be set
backward and forward or higher and lower and screwed to the side walls by the screw-bolt /z. The object of this is to set the comb k, placed below at in such a position regarding the cylinder which carries the saw-blades that the seed can pass with the requisite velocity through the opening between k and c. The curved plate 1 can be turned at o and secured by a screw (m) in a more or less inclined position, whereby the material to be worked is correspondingly pressed against the saw-blades.
If a more forcible action is requisite to gin the cotton properly, the plate d is depressed, whereby the teeth are projected farther over the grate, the curved plate 1 being at the same time moved forward. By giving the plate d the opposite position the fibres are less forcibly acted upon and the work proceeds more slowly. In case the seed does not fall freely enough from the machine, the plate i must be placed higher and farther forward; if the seed runs out too rapidly and is not sufficiently cleaned, the plate is to be set in the opposite position. At the rear of the cylinder, between the saw-blades, is placed a second or cleansing grate in a vertical position. It is secured to the plate A which beneath the cross-piece h can be pushed lip or down in grooves in the side frames of the machine. It consists of separate rods (q), which are connected with fi only by a screw (r), and if desired may receive a slightly lateral motion between the saw-blades. Between the lower end of the rods q and a screen covered with tin plate (s) is a slit, through which the coarsest particles of dirt pass out in the direction of the arrow r, the finer particles passing round and falling on the other side, as indicated by the arrow 2, while the cotton fibres themselves ascend in the direction of the arrow 3 on the plane I, also covered with tin plate, underneath which the space for the accumula tion of the impurities is shut off by the screen u.