Page:Popular Science Monthly Volume 39.djvu/201

Rh the finishing—the processes in which the mechanical advance has been fundamental. The various machines which now expedite the supplementary processes have grown out of the inventions which have attended these fundamental processes, and they are of special interest only to those practically engaged in the manufacture. Their invention has been suggested—in fact, compelled—by improvements in the primary machinery. We shall be struck, as we proceed, with the dependence of each forward step in this evolution upon some preceding advance, one invention making possible others, which without it would not have been dreamed of.

The wool comes into the mill dirty, greasy, burry, sometimes washed by the farmer, but generally just as it is sheared from the sheep, a filthy and unwholesome thing, giving little sign of the beautiful white and flossy substance into which it is soon converted. It must first be sorted, each fleece containing from six to eight qualities of sorts, which the careful manufacturer separates, devoting each quality to the purpose for which it is best suited. No skill in carding, spinning, weaving, or finishing, can possibly produce a soft or fine piece of goods from a coarse, hard fiber. When a woolen thread is to be spun to the length of 15,360 yards to a pound, or in the case of a worsted thread to twice that number of yards to a pound, everything depends upon care in the selection of the fleece and in the sorting. These sorts are impregnated with a greasy substance called the yolk or suint, caused by the animal secretions and the perspiration of the skin, a compound of potash and animal fat, which must be completely eradicated. The elimination of the yolk, dirt, and foreign substances, common to all wools, results in a shrinkage of from fifty to seventy per cent.

Our ancestors scoured their wool in tubs, much as our wives and daughters scour our clothes to-day. In the hand-washing of wool, a tub was filled with the suds, in which one or two men with long poles stirred the wool until clean, when they lifted it upon a traveling apron, which carried it between a pair of rollers which squeezed out the water. The same principle is applied in the automatic scouring now in vogue. Great forks or rakes seize the wool as it is carried by rollers from a feeding apron into the iron tanks, and by alternating motions of their teeth give it a thorough scouring. Thus cleansed, the wool is delivered by rollers to the drying machines, where hot air and great fans are now utilized to extract all the moisture without tearing the fiber. The ventilation—drying of wool by means of hot air—effects the object in one tenth of the time occupied by the old method of drying by exposure in the open air. So enormous has been the increase in the production of wool, stimulated in all quarters of the globe by the enlarged capacity for its manufacture; so different