Page:Paper and Its Uses.djvu/37

Rh machine is a very quiet place compared with the wet end.

At the end of the machine are stacks of rolls through which the paper is led if it is to receive what is known as "machine finish." If, however, the paper is to be super-calendered, it is led past one or more of the stacks of rolls, and as it is reeled off a fine spray of water is projected upon the paper. There are various means of producing a misty cloud, but the object is the same in every case, to restore some of the moisture which has been driven off, and to prepare the paper to receive the finish at the super-calenders. If the paper were finished bone dry it would not be possible to impart the required surface by super-calendering, and, too, the paper would at the first opportunity absorb moisture from the atmosphere, and various troubles would arise. The paper, now reeled, is ready for the finishing department, to which the next chapter is devoted.

Papermaking on the Yankee or single cylinder machine is conducted in the same manner as on the ordinary or Fourdrinier machine as far as the wet end is concerned, but the series of drying cylinders is replaced by a single cylinder of large diameter, as much as 10 feet in some instances: the paper passing round this heated cylinder is dried, and glazed on one side, hence the term M.G., or machine-glazed paper.

Mill numbers survive from the time when all mills were registered, and when paper was a dutiable article. The duty was repealed in 1861, but the mill numbers remain, and are additional to watermarks in distinguishing between papers of the various makers.

Watermarks have been used from very early times to serve as marks of distinction. The watermark used by John Tate of Stevenage in 1494 was an