state it is led between two pairs of calender rollers and formed into
a lap from 7-1/2 to 10-1/2 in. wide. In the cotton industry the _Heilmann
comber_, or some modification of that machine, is used to straighten
thoroughly the fibres of carded cotton, to cast out all below a
certain length, and leave only those that are perfectly clean and
approximate to uniformity in length. For fine yarns of medium quality
only part of the slivers required to form a thread are combed. But for
fine yarns of good quality all slivers are once combed, and those for
superfine yarns are twice, or "double combed." This machine is made
with six or eight heads, each of which is supplied with a ribbon lap.
One end of every lap is fed by a pair of rollers between the open jaws
of a nipper which immediately closes upon the sheet of cotton, but a
fringe is left protruding into the path of a cylinder, on whose
periphery either one set of 17, or two sets of 13, graduated needle
combs, and one, or two, fluted segments are secured. The first comb to
reach the cotton may have as few as 16, and the last 90 teeth per
inch. After the combs have passed successively through the overhanging
fringe of fibres, the nipper opens and a fresh length of about 3/16
to 4/10 of an inch is fed in. Meanwhile, a fluted segment on the
cylinder has moved up to support the fringe; a top comb, which was
inoperative when the cylinder combs were acting, has descended into
the fringe, and three rollers first return a portion of the material
already combed so that it may overlap that last treated. The rollers
then reverse the direction of their rotation; one of them and the
segment engage the fringe, and draw the tail ends of all free fibres
through the teeth of the top comb. The product of all the heads is
next united, condensed, formed into a continuous sliver, and deposited
in a can. One cycle of movements, therefore, only combs from 8/16 to
4/10 of an inch of each fibre; the top comb deals with the tail
ends, and the major portion of the work is done by the cylinder combs.
The foregoing operations are repeated at the rate of from 85 to 90
times per minute, during which from 15% to upwards of 25% of carded
material is removed; but this is capable of being spun into coarse
yarns. A comber invented by John W. Nasmith is a modification of the
foregoing. In his machine the cylinder combs act upon the forward en