Underneath the wire-cloth is placed a box called the “save-all” K, connected with the box E′. The water that passes through the wire-cloth contains a considerable quantity of very fine fibres, together with size, alum, clay, and colouring materials, that have passed through the wire, and which would be lost but for the arrangement now universally adopted. It flows into the box E′, and is pumped, together with the pulp that has passed through the knotter E (see p. 151), into the high box B, whence the mixed stuff flows on the sand-tables, to be again used to dilute fresh pulp from the stuff-chests. The following numbers will give some idea of the nature and amount of fibre, &c., which passes through. {155} The paper was made from esparto and straw, sized with rosin and starch. It contained 12 per cent. of clay. Grains per Gallon of Waste Water. Fibre 34·37 Clay 37·10 Starch 1·40 [Illustration: FIG. 51.] [Illustration: FIG. 52.] It is almost impossible to utilise the whole of the back-water passing through the wire-cloth in the way described. In some mills a portion of this water is made to pass through a “pulp-saver,” such as is shown in Figs. 51 and 52. It consists of a conical drum A, the circumference of which is covered with wire-cloth, and it is caused to revolve slowly by suitable gearing. The water enters by the pipe B, and passes through the meshes of the wire-cloth, the pulp gradually finding its way to the wider end, where it is discharged into the box C. It can then be returned to the beaters. This pulp-saver can also be used for recovering the fibre from other waste water, such as the wash water from the washing and beating-engines; or it can be used for freeing bleached pulp from water in cases where drainage or hydraulic pressure is not resorted to. If any pattern or name is required on the paper, it is produced by means of a light skeleton roll, called a “dandy-roll,” covered with raised wires in the form of the desired pattern, {156} placed between the suction-boxes, and pressing lightly on the still moist paper. The paper is thinned where the wire pattern presses, and thus a mark (water-mark) is produced. The other side of the paper has a mark corresponding to the wire-cloth; by using a dandy-roll covered with wire-cloth, the two sides can be obtained alike, such paper going by the name of “wove.” Paper in which a series of parallel lines are produced is called a “laid” paper. Some water-marks are produced by means of a dandy-roll in which the pattern is formed by depressions in the surface. The paper is thus _thicker_ where the pattern is formed than in the ground-work. De la Rue (Patent No. 8348, 1884) has patented the use of dandy-rolls so formed as to produce upon the paper the effects both of thickening and thinning.