Cotton as it comes from the bale is a compact, matted mass, mixed with bits of seed, leaves, sand, and other impurities, and it must pass through a number of machines before it comes out as a pure, light, fleecy product, with the fibers combed parallel. Even for a medium yarn a dozen machines are required to prepare the cotton for the spinning mule. A system of “counts” is used to indicate the size of yarn and it is based on the number of hanks it takes to make a pound. A hank is always 840 yards and 50’s would mean that the yarn is of such fineness that it would take 50 × 840 yards (=4,200 yards) of it to weigh a pound. Yarn below 30’s is graded as _coarse_; between 30’s and 60’s as _medium_ and above 60’s as _fine_. To prepare cotton as it comes from the bale for a fine yarn of, say, 100’s, it must go through no less than sixteen machines before it reaches the mule. We have not the space to describe all of these machines, but in general it will suffice to say that the cotton is graded by passing it through a series of pickers. These machines throw out the fibers and beat them so as to knock out the impurities and, at the same time, a blast of air blows out the dust. The cotton is treated by a number of such machines in succession and is finally delivered in a broad sheet known as a “lap,” after which it passes through the carding machine which combs out the tangled bunches and removes further impurities from the lap. The lap is then gathered into a compact rope known as a “sliver.” The sliver goes through the drawing rolls which serve to parallelize the fibers and make the sliver of even thickness, and at the same time to give a moderate amount of twist so that it will hold together, and it issues from the machine as “roving.” In the case of fine yarn the sliver issuing from the carding machine goes through a combing machine so as to remove the finer fibers. The bobbins of the roving are then placed in the spinning machine, which may be either the spinning mule or the ring spinning machine. The principal difference between the two is that the spinning mule is intermittent in its operation, while the ring spinner not only spins the roving into yarn but at the same time winds it up on a bobbin. [Illustration: FIG. 66.--ARKWRIGHT’S DRAWING ROLLS] ARKWRIGHT’S DRAWING ROLLS