The next invention we have to notice is by Mr. Wilks, 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 engaged 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, previously to its being subjected to the pressing rollers. Still more to facilitate the abstraction of the water, Mr. Wilks 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 mandril, 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 constituting 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 sectoral 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 pass 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 deposited 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, corresponding 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 manufacture of paper of different qualities: for thi3 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 hars 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 hog, 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.