WOOD PULP AND PAPER 



55 



the water which carries the pulp passes through the screen it leaves the 

 fibers behind to form an endless sheet. This sheet which still contains a 

 large percentage of water next passes on to a felt and is carried through 

 three sets of very heavy rollers which are pressed together under great 

 pressure. These press rolls squeeze out a large portion of the remain- 

 ing water. The sheet then passes over a series of heated rollers which 

 gradually dry out the remaining moisture and produce the finished sheets 

 of paper. 



There have been great developments in the refinements of the four- 

 drinier machines during recent years. From machines making news 



FIG. io. Diaphragm plate screen tilted for washing. This screen is located at the head 

 of the paper machine and its function is to screen the paper stock before it passes on to 

 the Fourdrinier wire. 



print paper of the width of 90 in. at a speed of 200 ft. a minute, the parts 

 of these machines have been lengthened and widened and refined until 

 at the present time these machines have a width of 206 in. and can pro- 

 duce paper at the rate of 700 ft. a minute. 



The pulp is carried out to the fourdrinier wire by means of an apron 

 and a special mechanical arrangement prevents the formation of too thick 

 a layer on the screen. On the fineness of the screen depends the quality 

 of the paper made, but it usually contains from 60 to 70 or more strands 

 of wire per inch. The frame which supports the rollers and the screen 



