n continuous
and intermittent spinning is that the former draws and twists
consecutively, whilst the latter draws and twists simultaneously. In
the _mule_, a creel (A, fig. 9), fixed at the back of the machine, is
designed to hold the rovings (B) in three or four tiers, from whence
they pass between three lines of drawing rollers (C) and two faller
wires (D). They are next led to spindles (E) mounted in a carriage (F)
whose wheels run upon rails (G) called slips. As the rollers (C) feed
the partially attenuated rovings the carriage recedes from the rollers
a little faster than the rovings are delivered, thus completing the
attenuation. Meanwhile, the spindles are revolved rapidly by bands
passing from a tinned cylinder (H) and the threads are twisted. This
twist goes first to the thin places where least resistance is offered
to it, leaving thick places almost untwisted; the pull of the
carriage, therefore, causes the fibres to slip most readily where
there are fewest twists, and gives to a thread an approximation to
uniformity in diameter. For fine yarns the rollers cease to rotate
slightly before the carriage has attained the end of its outward run,
or stretch, and at such times all attenuation is due to the pull of
the spindles upon the threads. On the termination of a stretch the
carriage stops, the twisting is completed, the spindles reverse the
direction of their rotation to back off, or remove the yarn which is
coiled round the spindles above the winding point, and whilst one
faller wire (D), operating on all the threads at once, descends to the
winding position of each spindle, the other rises to take up the yarn
delivered by the spindles. This completed, the carriage returns to the
roller beam, and in doing so the spindles revolve in their normal
direction to wind the stretch of 48 to 66 in. of yarn spun in the
outward journey. All the foregoing movements are regulated to succeed
each other in their proper order, the termination of one operation
being the initiation of the next.

Crompton's original machine was controlled manually throughout, but
later he devised means for moving the carriage out mechanically, for
stopping the rollers at the proper time, and for locking the carriage
whilst the spindles added the final twist to the threads. After which
all parts became stationary and the manual operations commenced. These
consisted in backing