is melted, and runs to the bottom of the mould. The melted tin being now poured in, the resin will float on its surface, and, consequently, as the tin rises, anoint the tin in every part, and act as a flux, and unite the two vessels. As soon as the tin is set, the last-mentioned mandrel is drawn out, and the external mould being removed, the lead now lined with tin is, when quite cold, ready to be submitted to the process of drawing. Various other equally simple processes are adapted to this purpose.

PAPER MANUFACTURE.

PAPER, that highly valuable substance, which enables us to communicate our thoughts to persons situate at the most distant quarters of the civilized globe, is manufactured from rags, by the aid of machinery.

It was formerly necessary to assort with great care the rags which were intended to be manufactured into paper; and none but the whitest and best, and which, consequently, were the most expensive, could be made into paper of the finest quality; but since the introduction of chlorine (which was discovered by Scheele) into our bleaching establishments, the necessity of this assortment has been greatly obviated; as it was soon conceived that that chemical agency, which was capable of bleaching linen, was also applicable to the whitening of the rag during the process of paper-making.

At that period of the process, when the rag is coming into a state of pulp, chlorate of lime, which was first manufactured by Mr. Tennant, of Glasgow, is introduced into the vat; and, by its chemical action on the fibre, whitens or bleaches the whole mass; thus enabling the manufacturer to produce a whiter and much finer quality of paper from rags of a secondary quality, than he had heretofore done from rags of the most expensive description. It must, however, be admitted that, as in all bleaching processes where the fibre is more or less deteriorated by the action of chlorine, the paper manufactured and whitened by this agent is not so strong as that formerly produced; as may be observed in some thick and beautifully white papers frequently offered to the public

at astonishing low prices, which are manufactured from coloured and inferior rags, with a superabundance of the chlorate of lime introduced in the process of the manufacture. By this, therefore, it is evident that the chlorate of lime, when used too abundantly, will rot or destroy the fibre of the whole; but when judiciously applied, it produces a paper of superior colour, and of adequate strength for all practical

purposes.

The paper-mill consists of a water-wheel, or other first mover, connected with a combination of toothed and other wheels, so arranged as to cause the cylinder in the washer, and the one in the beating engine, which will be hereafter described, to make from 120 to 150 revolutions per minute. On the same shaft, and of the same size as the water-wheel, is a toothed or cogged wheel, which plays in a pinion; the spindle of this pinion is furnished with a crank, which, by means of a connecting rod, gives a reciprocating motion to a lever, for the purpose of working two pumps, which raise a constant stream of water from the mill-dam. This stream of water is kept running through the rags in the washingengine, to carry away the dirt separated from them by the operation. The structure of an engine is more minutely explained by figs. 371, 372, 373, 374, &c.; fig. 371 being a section through the length of the engines, and fig. 372 a horizontal plan.

The large vat or cistern, A A, is of an oblong figure on the outside, the angles being cut off; but the inside, which is lined with lead, has straight sides and circular ends. It is divided by a partition, B B, also covered with lead. The cylinder C is fixed fast upon the spindle D, which extends across the engine, and is put in motion, as before described, by the pinion E, placed on the extremity of it. The cylinder is made of wood, and furnished with a number of teeth, or cutters, fixed fast on its circumference, parallel to the axis, and projecting about an inch, as is shown on a larger scale at fig. 375.

Immediately beneath the cylinder, a block of wood, H, is placed, and provided with similar cutters to those of the cylinder, which, when they revolve, pass very near the teeth of the block, but do not touch; the distance between them being capable of regulation, by elevating or depressing the bearings on which the necks D, D, of the spindle are supported. These bearings are made on two levers, F, F, which have tenons at their ends, fitted into upright mortises, made in short beams, G, G, bolted to the sides of the engine. (See also fig. 373.) The levers, F, F, are movable at one end of each, the other ends being fitted to rise and fall on bolts, in the beams G, as centres.

The front one of these levers, or that nearest to the cylinder C, is capable of being elevated or depressed, by turning the handle of the screw b which, as shown in fig. 373, acts in a nut a, fixed to the tenon of F, and comes up through the top of the beam G, upon which the head of the screw

takes its bearing. Two brasses are let into the middle of the levers F, F, and form the bearings for the spindle of the engine to work upon. The screw, b, is used to raise or lower the cylinder, and cause it to cut finer or coarser, by enlarging or diminishing the space between the cutters in the block, and those of the cylinder.

Near K, figs. 371 and 372, is a circular breasting made of boards, and covered with sheet-lead: it is curved to fit the cylinder very truly, and leaves but very little space between the teeth and breasting. An inclined plane, K, leads regularly from the bottom of the engine-vat to the top of this breasting; and at the bottom of it the block, H, is fixed.

The engine is supplied with water by a pipe, Q, bringing it from the pump; this pipe delivers it into a small cistern, M, adjoining, and communicating with the engine. The pipe has a cock, P, to stop the entrance of the water, when required, or to regulate the quantity of its discharge. The small cistern has a grating fixed across it, covered with a hair-strainer, to catch any extraneous matter which may come in with the water, or a flannel bag is sometimes tied over the orifice of the cock, P, through which all the water must be filtered. When the engine is filled with water, and a quantity of rags put in, they are, by the revolution of the cylinder, drawn between its cutters and the teeth of the block H. This cuts them in pieces, then, by the rapid motion of the cylinder, the rags and water are thrown over the top of the breasting, upon the inclined plane; in a short time, this raises more rags and water into that part of the engine-vat; and the tendency to restore the equilibrium puts the whole contents of the vat in slow motion, down the inclined plane K, and round the partition BB, by which they come to the cylinder again in about the space of 20 minutes; so that the rags are repeatedly cut and chopped in every direction, till they are reduced to a pulp.

This circulation is of advantage, in turning the rags over in the engine, and causes them to present themselves to the cutters in a different direction every time; for as the cylinder cuts or clips in straight lines, in the same manner as a pair of shears, it is requisite to cut the rags across in different directions, to reduce them to a pulp.

The manner of the cutting is this: the teeth of the block are placed rather inclined to the axis of the cylinder, as shown by fig. 374, but the teeth of the cylinder are parallel to its axis; therefore, the cutting edges, when they meet, are at a small angle, and come in contact first at one end, and then successively the contacts proceed along to the other end, so that any rags interspersed between them are cut in the same manner as they would be between the blades of a pair of shears. Sometimes the plates or cutters, k, in the block, are bent to an angle in the middle, instead of being straight, and inclined to the cylinder; in this case, they are called elbow plates, and of course the two ends are both inclined to the axis of the cylinder in opposite directions. In either case, the edges of the plate of the block cannot be straight lines, but must be curved, to adapt themselves to the curve which a line traced on the cylinder will of course have.

The plates or cutters of the block are united, by screwing them altogether, and fitting them into a cavity cut out in the wooden block H; their edges are bevelled away on one side only; as shown at k in the section, fig. 374. The block is fixed in its place by being made dove-tailed, and truly fitted into the bottom of the cistern, so that the water will not leak by it. The end of it comes through the wood-work of the chest, and projects a small distance on the outside of it, being kept up to its place by a wedge, so that by withdrawing this wedge, the block becomes loose, and can be removed,

to sharpen the cutters, as occasion requires. This is done on a grindstone, the plates being first separated from each other.

The cutters of the cylinder are fixed into grooves, cut in the wood of the cylinder, at equal distances from each other round its circumference, in a direction parallel to its axis; the number of these grooves is twenty; and for the washer, each groove has two cutters or bars put into it; then a fillet of wood is driven fast in between them, to hold them firm; and the fillets are kept fast by spikes driven into the solid wood of the cylinder. The beater is made in the same manner, except that each groove contains three bars and two fillets, as shown in fig. 375.

In the operation of the cylinder, it is necessary that it should be enclosed in a case, or its great velocity would throw all the water and rags out of the engine. The case is a wooden box, LL, enclosed on all sides except the bottom; one side of it rests upon the edge of the vat, and the other upon the edge of the partition B B. The lines, cc, represent the edges of wooden frames, which are covered with hair or wire-cloth; and immediately behind these, the box is made with a bottom, and a ledge towards the cylinder, which makes a complete trough.

The dark spaces, e e, in fig. 371, show the situation of two openings, or spouts, through the side of the case, which lead to flat lead-pipes, b, b, fig. 372, which are placed by the side of the vat; the beam, F, being cut away for them. There are waste pipes, to convey away the foul water from the engine; for the cylinder, as it turns, throws a great quantity of water and rags against the sieves; the water goes through them, and runs down into the trough at e e, and from thence into the ends of the lead pipes, b, b, fig. 372, by which it is conveyed away; d, d, fig. 371, are grooves for two boards, which, when put down in their places, cover the hair-sieves, and stop the water from going through them, if it is required to retain the water in the engine. This is always the case in the beating-engines, and therefore they are seldom provided with these waste-pipes, or at most on one side only; the other side of the cover being curved, to conform to the cylinder. Except this, the only difference between the washing-engine and the beater is that the teeth of the latter are finer, having 60 instead of 40 bars on its circumference; and it revolves quicker than the washer, so that it will cut and divide those particles which pass through the teeth of the washer.

The rags being now reduced to a state of pulp, we shall in the next place proceed to show the method of forming it into sheets of paper.

It was formerly the custom to allow a small, but sufficient portion of the pulp to flow on a sieve furnished with two handles, which sieve was agitated by a workman until the pulp had subsided or settled regularly throughout the surface. This, when it had passed through the usual processes of pressing, drying, &c. constituted a sheet of paper; and its texture was indicated by the fineness of the quality of the wire out of which the sieve was constructed.

This unmechanical and desultory mode of operation has been obviated by improvements effected by many ingenious persons; but the machines which are now almost universally employed, and which have most decidedly superseded all

other attempts at the same object, was the invention of the Messrs. Fourdrinier. The action and arrangement of this ingenious piece of mechanism consists in having a horizontal frame, of any required length, furnished with a roller or cylinder at each end, over which is stretched an endless web of brass wire, of the requisite texture or fineness for the paper about to be manufactured. At one end of the frame, parallel with, and immediately over, one of the cylinders, is a long angular trough, into which the pulp is received, whence it issues through a long slit or opening, which is regulated by a screw, and falls on the surface of the web beneath. At this period of the process, the cylinders are set in motion, and the web proceeds slowly forward with a tremulous motion, which arranges and disperses the pulp regularly over the whole surface of the web. This tremulous motion is imparted to the whole of the machinery by an eccentric move

ment.

As soon as the paper arrives in this crude and wet staté at the extremity of the web of the further cylinder, it is wiped and taken up by a larger cylinder, covered with felt or flannel, and is passed between a series of similar cylinders, and finally delivered to a reel, and wound off in a coil or hank so long as the operation proceeds. Thus, paper, by the action of this ingenious machine, may be manufactured to an unlimited length, and of any width that is compatible with the manufacture of wire web. The reel or winder being now withdrawn, the coil of paper is cut on both sides, forming sheets of the length and breadth of the machine and reel on which it is wound.

The arrangement of the different speeds of the various cylinders for moving the web, and afterwards pressing the paper, together with the action of the reel, and the tremulous motion that is imparted to the whole of the machinery by the eccentric or wiper, as also the regular supply of the pulp for the various qualities of the paper to be manufactured, form a most elegant combination of ingenuity and mechanical knowledge; and it is only to be lamented that the inventors and first proprietors, of this great source of national industry, should not have obtained a reward adequate to the benefit which they have conferred on their country.

The quantity of water which a paper-mill can command to turn its engines, generally limits the extent of its trade; hence the manufacturers should attend to every improvement of the machinery which can increase their effect.