When the stuff is principally prepared as above, it is carried to the vat, and mix ed with a proper quantity of water, which they call priming the vat. The vat is rightly primed, when the liquor has such a proportion of the pulp, as that the mould, on being dipped into it, will just take up enough to make a sheet of paper of the thickness required. The mould is a kind of sieve, exactly of the size of the paper to be made, and about an inch deep, the bottom being formed of fine brass wire, guarded underneath with sticks, to prevent its bagging down, and to keep it horizontal ; and further, to strengthen the bottom, there are large wires placed in parallel lines, at equal dis tances, which form those lines visible in all white paper, when held up to the light : the mark of the paper is also made in this bottom, by interweaving a large wire in any particular form. This mould the maker dips into the liquor, and gives it a shake as he takes it out, to clear the water from the pulp. lie then slides it along a groove to the coucher, who turns out the sheet upon a felt, laid on a plank, and lays another felt on it, and returns the mould to the maker, who by this time has prepared a second sheet, in another mould ; and thus they proceed, laying al ternately a sheet and a felt, till they have made six quires of paper, which is called a post ; and this they do with such swift ness, that, in many sorts of paper, two men make twenty posts or more in a day. A post of paper being made, either the maker or coucher whistles ; on which four or five men advance, one of whom draws it under the press, and the rest press it withgreat force, till all the water is squeezed from it ; after which it is se parated, sheet by sheet, from the felts, and laid regularly one sheet upon ano ther; and having undergone a second pressing, it is hung up to dry. When sufficiently dried it is taken off the lines, rubbed smooth with the hands, and laid by till sized, which is the next operation. For this they choose a fine temperate day, and having boiled a proper quantity of clean parchment or vellum shavings in water, till it comes to a size, they prepare a fine cloth, on which they strew a due proportion of white vitriol and roch-alum, finely powdered, and strain the size through it, into a large tub ; in which they clip as much paper at once as they can conveniently hold, and with a quick motion give every sheet its share of the size, which must be as hot as the hand can well bear it. After this the paper is pressed; hung up sheet by sheet to dry ; and, being taken down, is sorted, and, what is only fit for outside quires laid separately : it is then told into quires, which are folded and pressed. The broken sheets are commonly put toge ther, and two of the worst quires are placed on the outside of every ream or bundle, and being tied up in wrappers, made of the settling of the vat, it is fit for sale.
Paper is of various kinds, and used for various purposes ; with regard to colour, it is principally distinguished into white, blue, and brown ; and with regard to its dimensions, into atlas, elephant, imperial, super-royal, royal, medium, demy, crown, fool's-cap, and pot paper.
Fig. 1, Paper Mill, is an elevation of an engine paper mill ; (fig. 2) a plan ; and (fig. 3) a section of it ; the same letters refer to all the figures. It is contained in a square wooden chest, A B D E, lined with lead, and divided in the middle by a partition F F ; on the front and back of the chest, two short beams, G G, g g, are bolted ; they have long mortices through them to receive tenons, at the end of two horizontal levers, H H, which turn on bolts in one of the beams, G g, as centres, and are elevated or depressed by turning the nuts of two screws, h h, fixed to the tenon, and coming up through the top of the beams, G g, upon which the nuts take their bearing. Two brasses are let into
the middle of the levers, H II, and form the bearing for the spindle, I I, of the en gine to turd upon. K, is the cylinder, made of wood, and fixed fast upon the spindle, I I ; it has a number of knives or cutters fixed on it, parallel to its axis, and projecting from its circumference about an inch. L, (fig. 3) is a circular breast ing, made of boards, and covered with sheet-lead, which fits the cylinder very truly, and leaves but very little space be tween the teeth and the breasting, L. M, is an inclined plane, leading regularly from the bottom of the engine trough, to the top of the breasting ; and N is ano ther plane, but of smaller inclination, leading from the bottom of the breasting ; at the bottom of the breasting, beneath the axis of the cylinder, a block, P, is fixed, it has cutters of the same size, and exactly similar to those in the cylinder, which pass very near to those in the block, but do not touch ; this block is fixed by a dove-tail into the wooden bot tom of the breasting ; it comes through the wood-work of the chest, and projects a small distance from the outside of it, and is kept up to its place by a wedge, Q, (fig. 1); by withdrawing this wedge the block becomes loose, and can be removed to sharpen the cutters as occasion re quires.
The cylinder is turned round with great velocity by a small pinion, E, turned by a cog. wheel, which is turned with the in tervention of other wheels by a water wheel, so as to revolve about one hundred and twenty times per minute. This great velocity draws the rags and water with which the engine-trough is filled, down between the cylinder and the fixed cut ters in the block, I" ; and by this they are cut in pieces, and, passing round the par tition, I' F, come to the cylinder again : the breasting, L, by being so close to the cylinder, and its top so near the surface of the water, prevents the rags getting to the cylinder too fast, and by that means clogging it up, or raising it up from its bearing ; and if any rags come to the breasting rolled up, the action of the cy linder against the breasting tends to open them, and bring them in their proper di rection to the cylinder. The screws, 11 h, are used to raise or lower the cylinder, and cause it to cut finer or coarser by en larging or diminishing the space between the cutters in the block, P, and those of the cylinder.
A cover is put over the cylinder to pre vent the water and rags being thrown out of the engine by its greatvelocity ; it is a square box, a b d e, and has two small troughs at d and e, coming through the sides of the box. f g, are two hair sieves, sliding in grooves made in each side of the box : the cylinder, as it turns, throws a great quantity of the water and rags up against these sieves ; the water goes through them, and runs down the trough at d and e, and from thence into the end of leaden pipes, it i, (fig. 1), by which it is conveyed away : It are grooves for two boards, which, when slid down in their places, cover the hair sieves, and stop the water going through them. A consider able part of the rags thus thrown up by the cylinder, pass quite over it, and go down under it again.