Near the flow box, running at right angles across the machine, are two so-called “slices” about eight inches apart. These may be adjusted at various heights from the wire, in order to regulate the thickness of the paper. Their most important function is to make the thickness uniform from one side to the other of the sheet, and to create a pond which assists in forming the paper. The frame of the Fourdrinier has a joint near the first suction box, and a mechanical arrangement called a “shake” is located near the head box to impart a lateral shaking motion to the frame while the wire runs straight ahead, thus imitating the shaking of the hand mold. Beyond the couch roll is a series of press rolls, between which run endless felts to carry the soft, moist paper. Then follows a large series of steam-heated cylinders. Next a stack of iron calender rolls, and a set of reels. As soon as one reel is full a new reel is started and the paper from the first reel is slit by rotary slitters and made up into rolls of the desired widths on the winder. PAPER IN PROCESS It is an almost dramatic moment when the machine is ready to start. The machine tender opens the valves which admit the stuff from the flow box and a stream spreads out onto the wire. At a given signal the back tender starts the wire, and the endless white stream moves smartly forward. Then ensues the mechanical imitation of making paper by hand, only instead of forming sheet by sheet, the formation is a continuous process in the web. The shake of the machine mixes the position of the fibers in the “pond” behind the slices; the water runs like a downpour of rain through the moving wire into the save-all, leaving behind its burden of fiber, or “stuff,” as the mixture is at that stage called, in a white film. The suction boxes accelerate the expulsion of water, and the dandy roll closes the fibers together as the film passes beneath it. Then the web is carried between the couch rolls, when the water fairly pours out in the squeeze. As the top roll is felt-jacketed, the film sometimes sticks to it, as a slight suction is created in the pores of the felt. The back tender stands by with a hose to wash down the paper if it starts to adhere to the jacket. The paper is prevented from completely going around this top roll by a guard board which is fixed across the top. Many machines are now equipped with a “suction couch roll,” which does away with the need for a top roll, as the water is sucked, instead of pressed, out of the paper. At a given signal the back tender starts one edge of the film forward, by a skilful slap of the hand, which picks up the edge of the film and transfers it to the felt carrier between the press rolls. The remainder of the web is made to follow the lead of the first section, till finally the full width is transferred to the first felt, which carries it through the first series of press rolls.