Page:Encyclopædia Britannica, Ninth Edition, v. 18.djvu/241

 223 the size time to set. The web is then transferred to the drying machine at G, and passed over a series of spar drains H, H at a slow speed. These drums are fitted round their circumference with wooden spars I on which the paper rests, while a current of heated air from pipes under neath ascends through them and is driven against the inner surface of the paper by the fanners K, K, which revolve at a high speed. The great thing to be studied in this operation is to keep as low a temperature as possible, not above 80 Fahr. There may be any number of these drums ; the larger the number the lower the temperature at which the paper can br dried. In some mills as many FIG. 6. Single- Cylinder Machine. as two hundred of them go to a drier. After being wound up at the end of the drier the paper is ready for cutting in the ordinary way. The ordinary paper cutter (fig. 8) cuts from six to eight FIG. 7. Sizing and Drying Machine. webs at once. The webs to be cut may be seen on the drawing at a, a. The webs of paper from these are led between the leading rolls b, b through the feeding rolls c, c. These, by means of the change pulley d, are driven at such a speed that they feed the paper to the revolving knife at the exact speed necessary to give the length of sheet required. After pass ing the feeding rolls the paper passes on to the slitting knives e. These are circular revolving knives which slit the paper into the width required. From these the webs pass through the drawing rolls/, /to the revolving knife /, which, coming down with a sheer -r~ against the dead knife g, cuts them crosswise into the required length of sheet. The size of the sheet may be made longer or shorter, by altering the size of the expanding pulley h and the change pulley d. After being cut, the sheets of paper are caught by the end less felt i and carried forward to the table I; where they are arranged by boys. Another form of paper cutter which is employed for water-marked papers (see paper machine) is the single- sheet cutter, fig 9. In this cutter only one web of paper is cut at a time, but it can be adjusted to a much FIG. 8. Reel Paper Cutter. greater degree of nicety than the revolving cutter. After passing through the slitting knives A, which are in all