It is perhaps not so easy to see how it is that drawing rollers make the fibres of cotton parallel. As a matter of fact, it may be said that as each pair of rollers projects the fibres forward, the next pair of rollers takes hold of the fibres and draws their front extremities forward more rapidly than the other pair will let the back extremities of the same fibres pass forward. It is this action often repeated that draws the fibres straight, or in other words, reduces them to a condition in which they are parallel to each other. It is the usual practice to pass each portion of cotton through three separate frames in this manner, in immediate and rapid succession. The "slivers" or ropes of cotton made at the front of the first drawing frame, would be placed in their cans behind a second drawing frame and the exact process just described would be repeated. The same identical process would usually be performed yet a third time in order to secure the required objects with what is considered a sufficient degree of perfection. After this the cotton is usually deemed to be quite ready for the immediately succeeding process of "slubbing." =Bobbin and Fly Frames.=--The series of machines now to be dealt with, are distinguished more for their complicated mechanism in putting twist into the attenuated cotton and in winding it upon bobbins in suitable form for the immediately succeeding process, than for the action of the parts upon the cotton so as to render it better fitted for the production of strong, fine yarn. The manner in which these machines perform a part in the actual production of a thread or yarn is practically a repetition of the work of the drawing frame, with the great difference that the strand or thin rope of cotton leaves each machine of the series in a thinner and longer condition than when it arrived. This attenuation of the cotton roving is indeed the chief desideratum that bobbin and fly frames aim at, although they assist in making the strand of cotton more uniform by carrying still further to a limited extent the doubling principle so extensively utilised at the drawing frames. The basis of the operations are again the drawing rollers, brought to such a state of perfection by Richard Arkwright, and here it may be useful to remind the readers of this story how superior in this respect of general adaption Arkwright's method of spinning was to that of Hargreaves'. It will be remembered that the latter named inventor utilised a travelling carriage, for drawing the cotton finer, while the former performed the same work by drawing rollers. Although the travelling carriage principle was at one time somewhat largely utilised in preparing the rovings for the final process of spinning, it has long since entirely given way before the superior merits and adaptability of the drawing roller principle; and it is now this latter method which is universally employed.