By the process of doubling and drawing, the cotton is formed into a loose porous cord, the fibres of which are arranged side by side. This cord is still too thick for yarn, but it cannot be reduced in size by drawing merely, for if this were attempted it would break; a slight twist is therefore given, which by condensing the fibres allows the drawing to proceed. This is the commencement of the spinning process (which is, in fact, little more than a combination of drawing and twisting) and is called _roving_. [Illustration: Cotton Bobbins. Buffaloes with Bobbins. Roving.] The bobbin-and-fly frame is an exceedingly complicated machine, although the objects to be accomplished by it are sufficiently simple; namely, to give the roving a slight twist, and then to wind it on the bobbin. The first is easily done by the revolutions of the spindle; the second is more difficult. It is scarcely necessary to explain that the bobbins now under notice differ in no way from the reels in common use, except in being of very large size. The spindle which holds the bobbin is a round steel rod, driven by a small cog-wheel, fastened on the lower part of the spindle. The bobbin is slid upon the spindle, and the small bed or platform on which it rests is made to revolve by another series of small wheels. The spindle has two arms, called the _fly_ or _flyer_. This fly is fixed on the top of the spindle in such a way that it can be taken off in an instant, for the purpose of putting on or taking off the bobbin. One arm of the fly is hollow, the other solid, and all this serves to balance the machinery. One machine contains from thirty to a hundred and twenty spindles, which, for economy of space, are placed in two rows, each spindle in the back row standing opposite the space left between two spindles of the front row. The action of the machine is this:—The sliver having been drawn by the rollers, is twisted by the rapid revolutions of the spindle into a soft cord or roving; this enters a hole in the top of the spindle, and passes down the hollow arm of the fly; it is then twisted round a steel finger, which winds it on the bobbin with a certain pressure. [Illustration: Throstle. Flyer.]