The next invention we have to notice is by Mr. Wilke, one of the partners of the firm of Bryan, Donkin, & Co., engineers of great experience and celebrity in this department of mechanism; they having been almost unceasingly en gaged ,in the construction of the Fourdrinier, and other paper machines, from their earliest introduction to the present time : any improvement, therefore, emanating from that house, carries with it a recommendation for utility. The improvement contemplated by this patentee is the application of an additional roller to the Fourdrinier machines. The additional roller is to be perforated, and it is intended to facilitate the escape of the water from the pulp web, pre viously to its being subjected to the pressing rollers. Still more to facilitate the abstraction of the water, Mr. Wilke proposes to employ the pressure of the atmosphere, by making a vacuum within that part of the perforated roller on which the paper web rests. The method of making these rollers is described to consist of the following processes : a piece of sheet copper, brass, or other suitable metal, is bent and soldered in the form of a tube, whose length is equal to the circumference of the intended roller, and whose circumference is equal to the length of the intended roller, making an allowance for the waste at the ends. The tube is then to be drawn on trebletts, in the usual manner, and afterwards turned truly cylindrical on the mandril, on which it was drawn. A series of grooves, eight or ten in number, are then turned half through the tube, with a tool the sixteenth of an inch wide, and so made as to make the bottoms of the tubes as wide as their tops. The tube is then taken from the mandni, cut open, and bent inside out, and soldered in the form of another tube, whose length shall correspond to the circumference of the first, thus con stituting a hollow cylinder, with longitudinal grooves inside. It is to be again drawn, and turned with grooves to the amount of twenty-four in the inch ; these will of course cross the other at right angles, and, being cut half through as before, the entire surface will be composed of transverse ridges and rectangular perforations. When it is desired to employ the exhausting principle, a second perforated cylinder is introduced within the first; the inner cylinder must be made smooth inside, that it may fit air-tight upon a sectored cavity, extending from the axes to the circumference, enclosing about an eighth part thereof, opposite to the place covered by the web of paper, as it passes over the roller. The air is pumped from this cavity through the axis, which is made hollow for that purpose by an air-pump of the usual construction. When this method of abstracting the water is employed, the roller must be put in motion by a train of wheel-work, so arranged that it may coincide precisely with the motion through the machine.
1830. From a perusal of the specifications of patents granted about this period, it would appear, that the attention of the manufacturers of paper was rather directed to such improvements of the mechanism as were calculated to ameliorate and enhance the quality, than to such as might accelerate the process, and increase the quantity; and the ingenuity and talent thus called into action by rival manufacturers is deserving of record, were they of less practical utility. We shall therefore notice three of their inventions, in the order of the date of their patents. The first is Mr. Richard Ibotson's, of Stanwell, Middlesex.
Hitherto much difficulty has been experienced in clearing the stuff', or pulp, of which paper is made of the small knots which are invariably found in it, and which, if not separated, necessarily deteriorate the quality of the paper. The sieves or strainers which have been generally employed for separating the knots, have been either so wide in the meshes as to permit the smaller knots to pan through, or else they very soon get clogged up ; for it is evident that the fibres of which even the finest paper is made are considerably longer than one of the meshes in the sieve, and hence they will, instead of passing through, be de posited across the meshes, and immediately render the sieve useless. To remedy these imperfections, Mr. Ibotson manufactures his sieves or strainers (which he applies to the Fourdrinier machines) of metallic bars, giving the preference to gun-metal, made flat on the upper surface, and about half an inch wide, or, at all events, of a width greater than the length of any of the fibres in the pulp. The bars are strengthened by a projection extending along the middle of their lower sides, so that the cross section of one of the bars may be represented by the letter T. These bars are in a frame at a distance from each other, cor responding with the intended quality of the paper for which the sieve is to be used. He has designed, however, a very ingenious method of adjusting the distances between the bars, so as to make the same sieve answer for the manu facture of paper of different qualities : for this purpose he makes all the bars to taper uniformly, and fixes every alternate bar with its narrow end towards the same side of the sieve, and he frames the other bars together, but does not fix them to the sieve ; they are introduced between the fixed bars, with their narrow ends in a contrary direction. By this arrangement, it is evident that the distances between may be diminished or increased to any degree of nicety, with the greatest facility, by pushing the frame of loose bars forwards or backwards, which is effected by means of adjusting screws. The sieve is to be placed in a trough conveniently situated to receive the pulp from the bog, or machine by which the rags are torn to pieces, and agitated into the consistence of pulp. One side of the sieve, which is made in the form of a rectangular parallelogram, is attached by hinges to the trough, and the other is connected with a set of cam-wheels, by which it is elevated and depressed with great rapidity ; and when the sieve gets clogged up by the knots, which it separates from the pulp, its surface is to be cleared by a rake or brush, made of hard bristles. This
seems to be a highly ingenious invention; and, in the hands of a practical man, as it is, it cannot fail to become useful to the public. i The next patent, dated March 1831, is the invention of Mr. G. W. Turner, of Bermondsey, Surrey, which consists, first, in the construction of a new species of sieves for separating the lumps and coarse parts of the pulp from the finer portion, that the latter only be employed in the fabrication of the paper ; and secondly, in a peculiar mode of applying the sieves, so as to supersede the use of, and form an improved substitute for the vat and the hog. Mr. Turner describes several forms of sieves in his tion, slightly varied, but partaking of the same characteristic features. That to which he appears to give a preference is of a circular form, and consists of a series of concentric rings of thin metal, previously bent into a right angle, but placed with a flat side upwards, like the letter L reversed, thus, r r T ; they are arranged in concentric circles, leaving between each annular crevices about the fiftieth of an inch wide, and are fastened by screws, or solder, to radial arms underneath, proceeding from a central block to a peripheral band, which is about 8 inches deep, and 3 feet in diameter. The manner in which the sieves are used we will now explain. Upon the to of a square vat or cistern is fixed a framed standard, supporting in plummet. at its upper extremity, the axis of a vibrating beam ; to each end of this beam is suspended, by a rod or spindle, one of the sieves just described, the bottoms of which lie, when at rest, upon the surface of the pulp in the vat. The rods, or spindles, are jointed to the beam, to allow of their moving vertically by its vibration, which is effected by a rod connected to a revolving crank, the latter imparting sufficient motion to the sieves to cause their bottoms to be alternately lifted out of the pulp an inch or two, and then plunged underneath it. To this action of the sieves is added that of a rotatory motion, communicated to them from the first mover by means of pulleys fixed on their rods or spindles, which pass through centre holes in the standard frame, and are provided with swivel joints between the links that connect them to the beam, and thus admits of a rotative as well as a vibratory action, at the same time, which tends to dislodge any gross particles that may stick in the inter stices of the sieves, and, at the same time, to disturb and agitate the whole con tents of the vat. Thepulp, thus reduced to a smooth and homogeneous state, flows over a wide lip in the vat, directly on to the endless web or mould, and thus supersedes the necessity of the " hog." In 1832 Mr. John Dickenson took out a patent for the same important object, that of obtaining a perfectly uniform and smooth pulp, in order that the paper produced therefrom might be of a firm and even texture ; the process we proceed to describe, with reference to the figures on page 254. a a a, Ftg. 1, repre sents a section of a vat containing the pulp, which is to be regulated by a waste ; at b is a false bottom ; c c is a rotatory cylinder, through which that portion only of the pulp that is to be made into paper passes ; the knots, grit, dm. being prevented from entering by the wires which envelope the periphery of the cylinder. These wires are arranged spirally by a continuous coil, in the manner of a squirrel cage, but so close together as to leave only the one hun dred and fifteenth part of an inchbetween them. The wire recommended be for this purpose is to drawn of the represented in Fig. 2, the narrow under neath side d being fixed next to the cy 'nder, where it is to be fastened by rivets to the longitudinal bars e t, leaving the uniform space between the coils as before mentioned, which may, of course, be easily performed by a gauge. The spaces through which the pulp must pass are, therefore, longitudinal slits, two or three inches long, and only the one hundred and Meenth part of an inch wide. The ends of the cylinder are closed, except at the axes of rotation, which are formed of large tubes ; through these the fine pulp received into the cylinder flows off to the mould on which the paper is formed. As there would be a continual liability of the fine interstices of the cylinders becoming clogged, unless some means were adopted to prevent it, Mr. Dickenson employs what is technically termed a float (though it does not possess that precise character), which, by an up-and-down motion, agitates the liquid, and; by changing the course of the current through the wires, throws off whatever has accumulated on the outside of them. This float is a close vessel of strong copper, of nearly the length of the cylinder (four feet), and of the sectional figure seen at ff ; an horizontal bar passes throughout the lower part of this vessel, and also through the tubular axes of the cylinder, beyond the plummer boxes, in which the latter turn, where the horizontal bar is fastened to a vertical bar h at each end, that are connected to a lever i, whose fulcrum is at k. At 1 is a double cam, put in motion by a gear, in connexion with the wheel that actuates the rotatory cylinder ; every revolution of the cam lifts the lever i twice by means of the wipers In m, and, through the medium of h, the copper float ff also, about 11 inch each time ; and the "float" being somewhat heavier an the fluid in which it is immersed, falls immediately afterwards, producing the required agitation. A second improvement under this patent, consists in the knives usually employed in the transverse cutting of the endless sheets of paper ; these are usually two straight-edged blades, one of which being fixed, and the proper length of paper drawn over it, the other descends and divides the sheet by a similar action to that of shears. In lieu of the upper moving knife with a straight-edge, Mr. Dickenson employs one of an angular form, represented at a, Fig. 3, which is brought into contact with the lower fixed one, shown at a.