The engine is constantly supplied with fair water by a pipe, R, delivering it into a small cistern communicating with the engine ; the pipe has a flannel bag tied to the end to strain the water. In large mills, two engines exactly similar are used, but one set to act finer than the other; the rags are first worked in the coarse one, and afterwards in the fine one ; but some mills have but one engine, and alter it to cut fine by the screws, h h.
The paper proper for writing should he without knots, without any parts of the stuff not triturated, without folds, and without wrinkles, of a supple texture, its grain uniform and regular, softened in the exchange, and not destroyed by smooth ing. The ground of this paper must be extremely white, or shaded with a very light blue, which adds to its natural splen dor. It is of great importance that it be fully and equally sized, otherwise the writing cannot be well finished, and the turnings of the letters will be very imper fect. The paper used for drawing, or for coloured maps, is in some mills made from one kind of white stuff, either fine or middling ; in others, from a mixture of three or four kinds of stuff of different colours. The Dutch were not long ago almost wholly in possession of this manu facture. The same qualities are neces sary in this paper as in that for writing. The grain, however, must be a little more raised, although softened by the ex change ; for, without this grain, the pen cil would leave with difficulty the traces of the objects. Great care is also neces sary in the sizing of this paper, that the drawing be neatly performed, and also that the sinking of the ink or colours in to the irregularities of the stuff be pre vented.
The British and Dutch have had the greatest success in manufacturing paste. board, which they make either from a single mass of stuff on the form, or from a collection of several sheets pasted to gether. In both cases, the sheets of pasteboard are made of stuff not rotted, and triturated with rollers, furnished with blades of well tempered steel. By the operation of the exchange, and smooth ing continued for a long time, the British and Dutch obtain solid and smooth stuffs, which neither break under the folds of cloth nor adhere to them. The stuffs not putrified have another advantage in this species of pasteboard, namely, that of resisting the action of heat, which they experience between the folds of cloth, without wasting or tarnishing, and of con sequence, they may be used for a long time. In England they have at least
equalled any other nation in the manufac ture of this paper ; and even in Scotland they have arrived at such a degree of per fection in this art, that great part of what they manufacture is sent into England. It requires to be made of a soft and equal stuff, without folds or wrinkles, of a natu ral whiteness, and with a shade of blue. It must be sized less strongly than writing paper, but sufficiently well to give neat ness to the characters. The paper, thus properly prepared, yields easily to the printing press, and takes a sufficient quan tity of ink. The stuff must be without grease, and wrought with that degree of slowness as to make it spread equally over the form, and take a neat and regu. lar grain ; without this, the characters will not be equally marked in every part of the page ; and the smallest quantity of grease renders the sizing unequal and imperfect. Some artists, with considera ble success, both to meliorate the grain, and to reduce the inequalities of the sur face, have submitted this paper to the ex change. And it is proper to add, that a moderate degree of exchanging and press ing may be of great service after the sheets are printed, to destroy the hollow places occasioned by the press, and the relievo of the letters. Engraving requires a paper of the same qualities with the last mentioned, with respect to the stuff; which must be pure, without knots, and equally reduced ; the grain uniform, and the sheets without folds or wrinkles. To preserve the grain, it is necessary that it be dried slowly in the lowest place of the drying house. If it is submitted to the exchange, the effects of it must be mo derated with the greatest care, and the action of the two first presses must be equally distributed over the whole mass, otherwise the inequality of the moisture at the middle and sides will expose it to wrinkles in the drying. The sizing of this paper must also be moderate These circumstances are necessary to make it receive with neatness all the soft and de licate touches of the plate. The soft and yielding paper of Auvergne possesses all those advai.tages ; and accordingly, a great quantity of this, and of printing pa per, were formerly imported into Britain and Holland from France, where they still continue to rot the materials from which they make engraving paper.