and this takes place in endless succession as long as the motion is continued, and an uniform supply of pulp is kept up. It has been before stated, that when the surface of the cylinder emerges from the pulp at the point T, the quantity of fibre requisite for the composition of a sheet of paper is collected; but at that period so much water is contained among them, that it is necessary to drain off the greater part of it before it will admit of any sort of pressure usually made use of for squeezing out the water, and for compressing the fibres of rag together, for the purpose of making them cohere, and thereby giving tenacity to the paper. For this purpose the trough V, the construction of which is more fully explained in figs. 380 and 385, is fixed in the inside of the cylinder, and made to fit tight all round its upper edge. It has a communication with the pipe W, as is represented in fig. 385, where the pipe is pointed out by the letter n; and this pipe is connected with a pair of double-acting pumps X X, placed in a cistern of water, so that when those pumps are put in motion, the air contained in the triangular space, enclosed between the trough and the cylinder, is immediately drawn out, and consequently the pressure of the atmosphere takes place upon the surface of the cylinder, which is covered with pulp, in the state before described, and thereby rendered nearly impervious to the air. The immediate effect produced is the squeezing out the water, and laying the pulp down in a compact state on the surface of the cylinder, so that the paper cannot be disturbed at the point Z, by the pressure of the solid roller a. This part of the process I call the pneumatic pressure. The periphery of the roller a moves it exactly the same rate as the periphery of the cylinder R, and in the direction described in the drawing. The roller a is made to fit in exactly betwen the inside of the caps, described in fig. 385, so that it shall only press upon the paper covering the surface of the pervious cylinder. The surface of the roller A should be smooth, and the paper will adhere to it instead of the pervious cylinder R, and be led round by it to undergo a second pressure between the roller a and the roller b, which latter has a pervious surface, consequently the paper will be produced sufficiently dry for leading off to the cutting. It is well known by papermakers, that, independent of the quality of the materials, the strength, smoothness, and beauty of papers depend upon the arrangement of the fibres of rag of which it is composed; that in a well-made sheet of paper the fibres are ranged in a horizontal and parallel direction, and a manufacturer describing such a sheet of paper, would say that the stuff was well shut, which quality all paper must possess in a greater or less degree, because otherwise the parts of the sheet will scarcely cohere together, the surface will be rough, the thickness uneven, and the paper devoid of beauty, and not adapted for use. In the modes of paper-making exercised hitherto, this indispensable object has been accomplished, by shaking the mould or wire on which the pulp is settling, so that, as the water runs off, the fibres are laid flat upon the surface of the mould, and arranged in a parallel direction; but in making paper by the machinery above described, the stuff is perfectly well shut, without any shaking, the fibres of rag being deposited gradually, in a longitudinal direction, by means of the friction which takes place upon the cylinder, in consequence of its motion being in an opposite direction to that of the stream of pulp, the effect of which is to smooth down the fibres of rag as they are laid upon the cylinder, and it is necessarily continued during the whole time of the formation of the paper, and must be uniform throughout every part of it. The reason of introducing so large a quantity of water into the pulp, is in order that every fibre may be afloat separately, and at liberty to take a direction according to the influence of these courses.

It is to be observed, that the principle here developed would admit of other less eligible modifications, such as confining a body of the pulp on the surface of an endless well of woven wire, carried round cylinders, as in the outline section, fig. 389, or supporting it on a cylinder of a large size, as in the outline section, fig. 390, without applying the pneumatic pressure in either case.

In fig. 389 the cylinder a b c should be hollow, and have pervious surfaces. In fig. 390 the cylinder might be of a more simple construction than that described in figs. 380, 381, 382, 384, and 385, but unless of a very large size indeed, it could only be made use of for making very thin papers, be cause the water requires so long time to run off before the paper will admit of any mechanical pressure.

It is to be observed, that in making paper by this method, after a certain quantity of fibres of rag are deposited on the surface of the cylinder, it renlers the passage of the water and the accumulation of more fibres so difficult, that without a considerable height of pulp the pressure will not be sufficient to force the water through the cylinder, and the fibres of rag laying upon it, the consequence of which would be, that the fibres of rag accumu lated on the surface of the cylinder would be washed off by the pulp, or very much disturbed before they arrived at the point T, which is the level of the pulp in the back; to obviate this, it will be necessary to add the pressure of the atmosphere to the weight of the water in making thick papers, which may be done by extending one side of the trough V below the level of the pulp, so as to cause a suction under that part of the cylinder which is covered by the pulp, as well as under that part which has emerged from it. For this purpose a wider trough would be necessary; but at all events the exact proportion of the cylinder, covered by the trough, is not material, because it will be found by experience what width is sufficient for drying the paper, so as to enable it to have the pressure of the roller a. The roller a ought to press on the cylinder R about the point which is over one side of the trough V, and, according as the trough is shifted, the roller should be shifted also; but this pressure ought to be not less than forty-five degrees above the level of the axis, because, otherwise, part of the water pressed out of the paper will be absorbed by it again, whereas, from the position it acts in, in the drawing, fig. 387, the water will be sucked into the trough. The roller a should not be fixed in bearings, but confined down upon the cylinder by weights, suspended upon each end of the axis, which may be adjusted according to circumstances, and in all cases the principal pressure should be upon the roller b. The water which runs through the cylinder in figs. 387 and 388, and out at the end, falls in the first instance into the cistern C, from whence it passes through the pipe d into the cistern e, and from thence is, by means of a pair of double-acting pumps, ff, forced through the pipe K into the vessel L, so that it continually returns for the same purpose of conducting the pulp to the cylinder from the pipe J. The pipe G is a sort of gange, by means of which, after the pulp rises to a proper height in the vessel L, the remainder of the water is carried off into the cistern C, where there may be a waste pipe for conveying off the superfluous quantity. The water drawn from the cylinder R, through the trough V, by means of the air and water pumps X X, may run to waste. The size of the cylinder R, and of the trough V, must be regulated according to the substance and dimensions of the paper it is intended for making. Fifteen inches will be sufficient for the diameter of a cylinder intended for making paper equal in substance to a paper twenty-two inches by seventeen inches and a half, weighing twenty pounds per ream: the length of the cylinder is entirely arbitrary. The thickness of the paper made by a cylinder may be adjusted

in various ways: first, by using cylinders of various diameters; secondly, by accelerating or retarding the motion of the cylinder; thirdly, by varying the proportion of the surface of the cylinder, which is covered with pulp; fourthly, by varying the consistency of the pulp. The periphery of the cylinder ought to move at the rate of about thirty-six feet per minute; the pulp ought at all events to be very thin, and therefore the most eligible mode of adjusting the thickness of the paper would be by varying the proportion of the surface of the cylinder, which is covered with pulp; consequently for thicker papers a larger cylinder would be necessary, or a back may be made use of, extending higher up towards the point Z, so as to cover a larger proportion of the surface of the same cylinder: and for thinner paper a back might be made use of covering less of the cylinder, as in fig. 390, by means of the cock in pipe J. The quantity of pulp supplied to the cylinder can be adjusted with the greatest accuracy, consequently the thickness of the paper may be preserved uniform, or varied at discretion, provided the thickness of the pulp in the chest A, and the motion of the cylinder R be continued uniform. By means of the gauge pipes Q the level of the pulp in the back P can be varied till the most eligible point for the cylinder to emerge from the pulp is ascertained, and the supply of water through the piper must be adjusted accordingly. It may be laid down as a general rule, that the thicker the paper the higher should be the level of the pulp in the back. In order to close the trough V tight upon the cylinder R, the patentee proposes packing it all round the top, where it comes in contact withinside of the cylinder, as at the points nn, in the section fig. 380.

The mode of packing is so well known, that it is unnecessary to give any description, except the representation in the drawing. The friction of the pack Pupon the cylinder may be taken off by strips of woollen cloth or leather, particularly at the line across from the point S.

Figs. 391 and 392 are for the purpose of explaining a more simple mode of construction. A is a hollow cylinder, with a pervious surface, which may be used in cases when the pneumatic pressure is not applied; aaa is the thread of a screw; bbb represent cross-bars, carried across the internal surface, parallel with the axis. The best mode of constructing it will be to cast a cylinder with the bars in the inside, and to cut the screw deep enough to form an opening between every bar. It should be furnished with cross wires, e ec, and covered with wove wire, in the same way as the cylinder R. It might be made on a larger or smaller scale, according to the purpose for which it is required. The roller b, in figs. 387 and 388, may be made in this manner, but stronger, as a great degree of pressure is intended to take place upon it.

When the machinery is to work, the agitator and pumps should be set in motion, first by turning the shaft K, and then the cylinder R, by means of the cog-wheel P, which gives motion to the rollers a and b, by cog-wheels and r. The mode of giving motion, and the situation of the pumps aud stuff-chest, may be arranged according to convenience, but the motion ought to be perfectly regular,

COTTON MANUFACTURE.

COTTON is a fibrous vegetable substance, the produce of a small tree called the gossypium, or cotton plant, which grows naturally, and is much cultivated, in the tropical regions of Asia, Africa, and America.

The cotton, when collected from the pod, contains the seed, and pieces of the husk by which it was enveloped is attached to it; it has therefore, preparatory to being subjected to the operation of spinning, to undergo a process that will divest it of these superfluous parts. The ancient mode of effecting this was by what is termed bowing it; that is, exposing it to the action of a bow, about four feet long, such as is used at the present day by hatters. The process consisted merely in placing the cotton upon a square table with horizontal chinks cut through it, and submitting it to the repeated action of the bow until the dust, seeds, and superfluous parts had separated and fallen through the chinks. This inconvenient and desultory mode has in modern times been superseded by a far more effectual and expeditious one, by the application of a machine called a gin. Gins are of two kinds, the one called the rollergin; the other the saw-gin.

The roller-gin is represented in fig. 399. It consists of two shallow fluted rollers a and b, placed so near to each other, that when the cotton is thrust against the line where they enter into contact, they immediately seize hold of it and draw it in between them, while the seeds and other particles, not being able to pass through, fall into the box K, and are, by the slanting direction of its bottom, delivered on one side. The motion is communicated by means of the treadle and crank C D, and is equalized by the fly-wheel E. The cotton is presented to the rollers over the board fg, and is drawn between them, and delivered at I H. In South America this kind of gin is much used, and a negro working with one of them can clean from 30 lbs. to 40 lbs. weight of cotton per day, which, however, is considered heavy work.

The saw-gin is given in section in fig. 400. The cotton is thrown into the receptacle A B, on that side marked C D, which is formed of strong wires placed parallel to each other, to admit the circular saws E, fixed on the axis F, behind the grating, about an eighth of an inch apart, to pass between them. By this means, the teeth of the saws seize hold of the cotton and draw it through the bars; and the seeds and other superfluous parts, being too bulky to pass through, remain behind, and eventually fall through the aperture G. The cotton is brushed from the saws by a circular brush H, made to revolve rapidly on its axis. The motion is communicated by manual or any other power applied to the axis F, upon one end of which is the wheel K, acting in the pinion M, fixed to one end of the axis of the brush.

The application of the power of horses to either the roller, or saw-gin, would greatly aid the process, which, as we before have stated, is considered heavy work for the negroes,

and on that account is much avoided. An objection has been started to the applying of this power, under a supposition, that the animal by changing his speed would injure the cotton; it is almost superfluous to add that many simple contrivances may be adapted to equalize the motion, and prevent these dreaded effects.

When the cotton has undergone either of these processes, it is packed, and exported to the European markets.

When it arrives in this country, it is again submitted to the action of machinery for the further separation of the extraneous matter, unless it is to be spun into coarse yarn, when the preceding process is considered sufficient.

The first machine that we shall describe as used in this country for the further clearing of the particles is called a picker, and is represented in fig. 393. A and B are two rollers, having an endless-cloth, C D, stretched over them. This cloth is called the feeding-cloth, and its upper surface is, by the revolution of the rollers, always carried towards D. E and F are two fluted rollers, which nearly touch each other, and revolve, so that their touching surfaces pass towards G H. GHIK are cylinders, covered on their outer surfaces with long blunt pins, making about 250 revolutions, in the direction of the letters, per minute. LL is a grating of wires for the seeds to fall through, when the cotton carried by the feeding-cloth is delivered by the small rollers upon the face of G H. By the rapid revolution of G H, the cotton is thrown against the top O P, and is carried forward and delivered upon the cylinder I K, which in like manner carries it rapidly round, draws it over the grating, and delivers it back upon the lower face of G H, which after having drawn it over the remainder of the grating, and divested it of the remainder of the seeds and particles of dust, deposits it in the box R R.

This machine is liable to injure the staple of the cotton, and is therefore superseded by another called a batter, represented in fig. 401. In this machine, the feeding-cloth upon the rollers A and B carries forward the cotton to the rollers c and d, which deliver it upon the curved rack or grating d e, while a scotcher, g h, revolving rapidly upon its axis, strikes the cotton with its two edges g and h, and divides it; at the same time a draught of air, created by the revolution of the fan I, blows the cotton forward over the grating KK, divests it of the superfluous parts, and ultimately deposits it in a box at the end.

The cotton is now considered in a state fit for the operation of spinning; which is differently performed according to the purposes to which the yarn is to be applied. The different sorts of spinning may be classed under the respective heads of Jenny, mule, and water spinning.

Mule-spinning, which is by far the most perfect process, and by which the finest yarn is produced, shall first have our

attention.

In this process, when the finest yarn is to be produced, the cotton, instead of being submitted to the operation of either of the machines before described, is cleansed entirely by the hand. The mode of effecting this is, by spreading the cotton