The next operation is the drying, which is performed in the following manner : Posts about 10 or 12 feet high, are set up at the distance of 10 feet from each other, pierced with holes at the distance of six inches one from another ; two spars, with ropes stretched between them, at the distance of five inches one from another, called a treble, are placed about five feet high between these posts, supported by moveable pins pushed into the holes in the posts. The workman takes up three or four sheets of pa per, and puts them on a piece of wood in the form of a T, passing this T or cross between the ropes, he leaves the sheets hanging on them, and goes on till all the ropes are full ; he then raises the treble, and puts another in its place, which he fills and raises in like manner. Nine or ten trebles are thus placed in every set of posts. The sides of the drying room have shutters, which can be open ed at pleasure. In good weather paper is dried in a day, but in moist weather, longer time is required. For as sisting in drying, steam pipes arc used in some mills. When the paper is dry, it is taken down and laid neatly in heaps, to be sized Size is made of pieces of skins cut off in tanning, or sheeps feet, or any other glutinous sub stance. They are boiled in a copper, to a jelly ; and this jelly being strained, and set by for use, a small quantity is then dissolved, and a little alum is added. The work man then takes about four quires of paper, and spreads it out in the size, taking care to get every part of it wetted. This is rather a difficult operation. Some of the size is then pressed out, and the paper parted. Being again pressed, it is taken again to the drying room, and dried as before, care being taken not to dry it too rapidly ; as in that case great part of the size would fly off in moisture. Three days arc necessary for this drying. When the pa per is thoroughly dry, it is carried to the finishing house, where it is again pressed pretty hard ; it is then picked, which is done by women with small knives, who take out the knots, and separate the perfect from the imperfect ; the paper is then again pressed, and given to the finisher, who counts it into quires .and reams, and folds it ; it is again pressed in reams, tied up, and sent off; the whole operation takes about three weeks in general. A good finisher can count 200 reams or 96,000 sheets in a clay of ten hours. It is pressed often to give it a good skin or surface, as it is called. hot pressing is clone by smooth ed pasteboards, between every one of which, a sheet of pa per is placed, and between every 40 or 50 pasteboards a heated plate of iron. This gives it the fine smooth sur face we see in writing papers.
We now come to give an account of the various ma chines invented to do away with the use of the mould. The most important of these is Fourdriniees, Plate CCCCLVII. Fig. 4. A is a vat in which there are two agitators, to keep the pulp suspended ; from this the stuff runs by a sluice into b, and from that on to a web of wire cloth c c c c, four feet wide, and 24 long ; the two ends of which are sewed together, this wire-cloth is stretched on several rollers k k k : the part of it next the vat runs on a number of small level rollers, m m are two rollers above the wire-cloth ; below these passes an endless strap b, which returns over the rollers above, and which forms a ledge to confine the stuff while in a fluid state. There is
one of these straps at each side of the web. A rod from an eccentric wheel shakes the part of the wire-cloth next the vat. The rollers being all set in motion, and the wire cloth with the stuff running on it, moving on towards d, the rod shaking it so as to make it part with the water, forms the stuff into paper ; when it arrives at the rollers d d, it passes between them, undergoing a slight pressure ; here the paper is laid on the web of felting c e, the two ends of which are also sewed together, and the web of wire-cloth returns below, as is seen in the plate ; the paper and felt are then hard pressed between the rollers ff ; when the paper arrives at g, it is detached from the felt, and wound on the reel h ; when this reel I, has 16 or 18 quires on it, it is removed, and another reel i substituted, and the paper being cut off, the reel h is ready to be sent to be parted ; or, if coarse paper, to the loft. The dotted line marks the passage of the paper from the vat to the reel. All this is done by machinery, which is constructed so that no part shall go too quick or too slow. There are a number of other contrivances, which our limits will not permit us to describe. For a full account of the machine, see the Repertory of Arts, vol. xiii. second series.
The next machine we have to give an account of, is Mr. Dickinson's. Plate CCCCLVII. Fig. 5.
A is a hollow revolving cylinder, made of brass, and polished outside and inside. From B to C, a great num ber of small holes are cut in the circumference of the cy linder, and over these holes a wire-cloth is neatly sewed. The stuff or pulp fills the vessel d, and the water runs in to the cylinder, as it revolves, and leaves a portion of pulp on the wire-cloth ; the parts EE form a box in the cy linder, which does not revolve, and the edges of this box FF couches, or rubs against the interior of the cylinder ; o is a pipe in which an air-pump works, which exhausts the box G. When the wire-cloth with the pulp on it arrives above the exhausted space G, the pressure of the atmosphore fixes the sheet on the wire-cloth, and gives it some consistency and regularity. The cylinder H, made of a hard body, covered with felt, then receives the sheet; when it reaches the point I, it adheres rather to the cy linder II than to the wire-cloth; it is then pressed between the cylinders H and K, taken off at L, and finished in the same way as paper made by the hand.
Mr. Cameron's machine, near Edinburgh, is a very good one, by common moulds, fixed in a frame which has a revolving motion. The pulp runs on them as they pass by a particular place. The couching is done by.the moulds as they move along, being made to turn upon their face, which comes in contact with a revolving and endless web of felting ; there they receive a pressure, and as they pass on, are again reversed to receive the stuff for another sheet.
This machine, which has been only at work for a few months, seems to have been an improvement upon that of Cobb's of London, but sufficiently improved as to entitle the present workers of it to a patent, against the opposi tion of Cobb. It promises to succeed, although it cannot come into competition with that of Fourdrinier's i in point of expedition or extent of work. It is better suited than the latter for a small mill, and may probably become valuable for the making of laid papers, which arc necessarily at present made by hand.