Placed over the cylinder, and extending for nearly one-half of its circumference, are what are technically known as the "flats."
These are narrow iron bars, each about 1⅜ inches wide; each being covered with steel wire teeth in the same manner as the cylinder; and each extending right across the width of the cylinder, and resting on a suitable bearing termed the "bend."
They are formed into an endless chain containing about 108 "flats," but only about 44 of which are in actual work at one time; this endless chain of flats being given a slow movement of about 3 inches per minute.
Here it may be said that the various working parts are set as close as possible to each other without being in actual contact, the usual distance being about 1⁄143rd of an inch determined by a specially constructed gauge, in the hands of a skilled workman.
The steel teeth of the flats, being set very close to those of the cylinder, catch hold of and retain a portion of the short warty fibres and fine impurities that may be on the points of the cylinder teeth, the amount of this reaching about 3 per cent. of the cotton passed through the machine. In addition to this the teeth of the flats work against those of the cylinder so as to exercise a combing action on the cotton fibres.
Having passed the "flats," the cotton is deposited by the cylinder on what is termed the doffer. This is a cylindrical body, exactly similar to the main "cylinder" excepting that it is only about half the diameter, say 24 inches. Its steel wire teeth are set in the opposite way to those of the cylinder, and its surface speed is only about 75 feet per minute. These two circumstances acting together enable it to take the cotton fibres from the main cylinder.
The operations of carding may now be said to be practically performed, as the remaining operations have for their object the stripping, collecting, and guiding of the cotton into a form suitable for the next succeeding processes. The fleece of cotton is stripped from the doffer by the "Doffer Comb," which is a thin bar of steel, having a serrated under edge, and making about 1600 beats or strokes per minute. From this point cotton is collected into the form of a loose rope or "sliver," and passed first through a trumpet-shaped mouth, and then through a pair of calender rollers about six inches wide and four inches in diameter.
Fig. 16.—Lap, web, and sliver of cotton.
Finally, the sliver of cotton is carried upward, as shown in the illustration ([Fig. 15]), and passed through special apparatus and deposited into the can, also shown. This latter is about 10 inches in diameter and 36 inches in length, and the whole arrangement for depositing the cotton suitably into the can is denominated the "Coiler." In the next illustration ([Fig. 16]) are shown three forms in which the cotton is found before and after working by the Carding Engine. That to the left is the lap as it enters, the middle figure is part of the web as it comes from the doffer, and that to the right is part of a coil of cotton from the can.