_Paper Making_ is an important adjunct of the printing art, and its formation cheaply into long rolls of uniform strength is an essential condition of success in the rapid web-perfecting printing press. A Frenchman named Louis Robert about 1799 was the first to make a continuous web of paper, and in 1800 he received from the French Government a reward of 8,000 francs for his discovery. His invention was subsequently taken up and carried to a success by the great English paper makers, the Fourdrinier Brothers, whose name has been given to the machine. In the Fourdrinier process rags are ground to a pulp by a revolving beater (Fig. 125) working in a tank of water. The pulp, duly beaten, refined, screened, and diluted with water, is then piped into the “flow-box” of the Fourdrinier machine. The “flow-box,” shown on right of Fig. 126, is a deep rectangular chamber extending across the full width of the machine, from which the pulp flows out in a thin stream onto an endless belt of 70-mesh wire cloth which runs over end rollers. To prevent the stream of pulp from flowing laterally over the edges of the belt, two endless rubber guides or bands, two inches square in cross section, travel with the belt over the first twenty feet of its length, and run over two pulleys above the wire cloth. The upper half of the wire cloth belt is supported by and runs over a series of closely juxtaposed rollers. As the pulp passes from the “flow-box” the particles of fibre float in it just as an innumerable multitude of particles of cotton fibre would float in a stream of water. To unite and interlace the fibres the wire cloth belt is given a lateral oscillating or shaking movement, which serves to interlock the fibres. Meanwhile the water strains through the wire cloth, leaving a thin layer of moist interlaced fibre spread in a white sheet over the surface of the belt. The separation of the water is further assisted by suction boxes which extend across close beneath the upper run of the belt and are connected to suction pumps. [Illustration: FIG. 126.--FOURDRINIER PAPER MACHINE.] The wire cloth with its layer of moist pulp now passes below a roll which compresses the fibre, and then leaving the machine seen in Fig. 126 it passes below a second and larger roll covered with felt, which presses out more of the water. The fibre next passes to the “first press,” where it is caught up on an endless belt and passed between two rollers where more water is pressed out of the sheet. Then it passes through a “second press,” and finally the sheet commences a long journey up and down over a series of steam-heated drying rolls, by which the sheet is dried.