It must be understood that the comber is only used by a comparatively small proportion of the cotton spinners of the world. For all ordinary purposes a sufficiently good quality of yarn can be made without the comber, and no other machine in cotton spinning adds half as much as the comber to the expense of producing cotton yarn from the raw material.
To show this point with greater force, it may be mentioned that the comber may make about 17 per cent. of waste, which is approximately as much as all the other machines in the mill put together would make.
Its use, however, is indispensable in the production of the finest yarns, since no other machine can extract short fibre like the comber. It is seldom used for counts of yarn below 60's and often as fine yarns as 100's or more are made without the comber. In England its use is chiefly centred in the localities of Bolton, Manchester, and Bollington, although there is a little combing in Preston, Ashton under Lyne, and other places.
Perhaps its greatest value consists in the fact that its use enables fine yarns to be made out of cotton otherwise much too poor in quality for the work; this being rendered possible chiefly by the special virtue possessed by the comber of extracting all fibres of cotton below a certain length. This of course has led to the increased production and consequently reduced price of the better qualities of yarn.
Reverting now to the Heilman Comber as it stands to-day, an excellent idea of the machine as a whole will be gathered from the photograph in [Fig. 31].
There are usually six small laps being operated upon simultaneously in one comber. Each small lap being from 7½ inches to 10½ inches wide, being placed on fluted wooden rollers behind the machine, is slowly unwound by frictional contact therewith, and the sheet of cotton thus unwound is passed down a highly polished convex guide-plate to a pair of small fluted steel rollers.
Both the wooden and the steel rollers have an intermittent motion, as indeed have also all the chief parts of the machine concerned in the actual combing of the cotton. The rollers, during each intermittent movement, may project forward about ⅜ of an inch length of thin cotton lap.
Fig. 31.—Combing machine.