the machine over the lower "couch roll" (g). Between the breast roll and the lower couch roll support is given to the wire by a number of hollow brass rolls of smaller diameter in order to ensure a perfectly even surface.

The peculiar shaking motion which the hand maker imparts to the mould after lifting it from the vat is also imitated on the paper machine; the whole of the frame carrying the wire is firmly supported by the lower couch roll whilst the supports under the breast roll rest on movable pivots. A rapid to and fro motion of the frame, gradually diminishing in intensity towards the couch roll, is produced by means of a crank shaft.

This shaking motion, to a certain extent, prevents the fibres from placing themselves in parallel positions on the wire and at the same time promote the intertwining and felting upon which the strength of the paper so largely depends. The width of the paper produced may be regulated at will by adjusting the two "deckle straps," (e) which are carried and guided by suitable grooved pulleys on the deckle frame. On modern machines suitable arrangements are provided which enable the shifting of the deckle straps and the corresponding alteration of the width of the web to be carried out without necessitating stoppage of the machine.

The water which passes through the wire and which carries along with it a certain amount of fibres, loading materials, size, &c., is called the "back water."

As already mentioned, to obtain uniformity in certain classes of paper it is necessary to collect the back water and to use it in place of fresh water for diluting the pulp coming from the stuff chest. It being in many instances impossible to use all the back water for this purpose, suitable "save-alls" or "fibrecatchers," such as the "Bertram " and the "Füllner," are provided. The use of these latter is of the utmost importance, not only upon the ground of economy, but also in connection with the question of the prevention of river pollution; this problem, with which the paper-maker is constantly confronted, may be solved to a very considerable extent by the provision of suitable arrangements for the purification of the back water in the mill.

The speed at which the wire travels varies according to the kind of paper made and according to the construction of the machine; 500 feet per minute is the highest speed obtained on "news" machines in the author's experience.

During its passage along the wire the pulp gradually loses water but not, however, to a sufficient extent to give such a consistency and strength to the web that it can be removed from is support without breaking; in order to make this possible recourse is made to artificial drying. For this purpose two or more suction boxes (h), constructed either of wood or metal, and divided into compartments, are placed immediately below the wire, before it reaches the couch rolls; an outflow pipe of a certain length is fitted to the bottom of each box. The box, when filled with water, with the outflow pipe closed and with the wire carrying the wet paper on the top of it, is, practically speaking, hermetically sealed. If the tap provided on the outflow pipe is now opened and if the box is just kept full of water, a partial vacuum is produced underneath the paper and the atmospheric pressure rapidly forces the water out of the web into the suction box. When suction by means of outflow pipes proves insufficient, specially designed vacuum pumps are fitted to the suction boxes.

Water-marks are not produced in "machine made" paper by wires sewn on to the wire cloth upon which the paper is formed, as in the case of "hand made," but by means of the so-called "dandy roll;" this is a cylinder, covered with wire gauze, on to which the design of the water-mark is sewn and which, by revolving and pressing upon the surface of the soft paper, usually between the suction boxes, produces the required impression. The first" dandy roll," at the time called a "wove riding roll," was made (according to Hofmann) by John Marshall of London and supplied to Matthew Towgood in the year 1827. Wove paper is produced by covering the dandy roll with ordinary machine wire.

The web of paper, still containing a considerable amount of water, has next to pass between the couch rolls. It has already been pointed out that the wire is conducted back over the lower couch roll on the top of which, but generally slightly behind, revolves the top couch roll (); this top roll is covered with a tightly-fitting felt tube, called the "jacket," and is firmly pressed against the lower roll by means of screw or lever pressure. scraper, called the "doctor," a spurt pipe and a revolving brush are usually provided for the purpose of freeing the felt from particles of paper which it may have retained.

A

After the paper has been pressed between the couch rolls it should possess sufficient

strength to allow of its being parted from the supporting wire. It now travels, unsupported for the first time, for a short distance to the "first press felt."

Considerable skill is required on the part of the men in conducting the moist web of paper from the couch roll to the first endless press felt; along this felt the paper travels to the first wet press (), which consists of two bowls made of cast-iron or of granite, or of cast-iron covered with hard rubber or bronze. Pressure is applied to the top roll and a considerable amount of water is thus pressed out of the

eliminated by drying. Slow drying, as is customary with hand-made paper, is out of the question on account of the enormous production of our modern quick running paper machines. The first Fourdrinier machine, built by Bryan Donkin, had no drying arrangement, the paper being taken from it in a moist condition, cut and dried in a drying chamber. J. B. Crompton, of Manchester, may be considered as the inventor of the drying cylinders now attached to the paper machine. The number of drying cylinders varies very considerably with the kind of paper made and

paper; small particles of paper which stick to the top roll are removed by a steel "doctor."

The paper, after leaving the first press rolls, is always slightly marked on the side on which it has been in contact with the felt, but a uniform finish on both sides of the paper is obtained by passing the web on to another wet felt and with this through a second wet press (k). This time, however, the paper enters the press from the back so as to bring the other side into contact with the upper press roll.

The action of the wet presses naturally depends, to a very considerable extent, upon the readiness with which the felts are capable of absorbing the water. The felts, therefore, have to be changed frequently and cleaned in special felt washing machines.

At this stage the paper still contains a considerable amount of moisture which has to be

with the speed at which the machine runs ; these cylinders are made of cast iron, highly polished, and are heated by steam. As the paper comes from the last wet press it is conducted to the drying cylinders (4), against which the paper is pressed by an endless felt, called the "drying felt" (m). Special stretching rollers are provided in order to keep the felts tight and in many cases the drying of the felt is facilitated by the addition of separate drying cylinders (2).

The drying cylinders are generally arranged in batteries and in some machines the paper is passed through a small calender called the "smoother," which is placed in front of the last set of cylinders. The "smoother" consists of a pair of highly polished chilled iron rollers to which pressure is applied by means of screws and levers. The paper being in a

damp condition, whilst passing between these rollers, is capable of taking a high class finish. It is always preferable to perform the drying as slowly as possible because rapid drying, as also drying at high temperatures, usually results in a paper of inferior quality, especially in so far as its strength and sizing are concerned. The first two or three cylinders should be but slightly heated, because overheating at this stage frequently causes cockling of the paper.

The surface presented by the paper after it leaves the last drying cylinder is not sufficiently even or smooth for many purposes. Printing papers which have been engine-sized are usually finished by a passage through one or more sets of calender rolls (0), forming part of the paper machine; these are placed immediately after the drying cylinders.

After having passed over the drying cylinders the fibres constituting the paper are in a state of absolute dryness and therefore incapable of taking a superior finish. It being impossible to regulate the drying so as to leave a definite amount of moisture in the paper before passing it through the calender

a wet end (a), similar to that of an ordinary Fourdrinier machine but contains only one drying cylinder (b), this being of large diameter and having a very highly polished surface.

The paper is taken from the couch press (c) on to an endless felt (d), by which it is pressed against the surface of the cylinder so that it remains in contact until perfectly dry. After leaving the paper the felt is run through a washing machine (e), in order to remove absorbed impurities.

Paper machines with two wet ends have been constructed with the object of pressing both webs together as they come from the couch rolls. Differently coloured papers, as well as papers of varying composition, may thus be firmly united.

In the Imperial Russian paper mills, papers bearing peculiar water-marks very difficult to counterfeit, are made on a machine which consists of three wet ends of the "Fourdrinier " type. Each of the three webs is separately water-marked and the machines are so accu

moist sheets together, the water-marks register perfectly.

The bowls, of which there are usually from four to twelve in one calender, are made of chilled iron and in some calenders provision is made for heating some of the bowls with steam; pressure is applied by screws and levers or in modern arrangements by means of hydraulic rams. In many instances the paper is cut on the machine lengthways, so called "slitter knives" (p), being used for this purpose.

The reeling apparatus (g), forms the final part of the paper machine. It consists of a number of rollers each of which is independently driven and on which the paper is wound; provision being made so as to allow of the finished reel of paper being replaced by an empty core, without causing loss of paper.

Among the other types of paper machines I will first describe the "single cylinder machine" or "Yankee machine," also called the "M.G. machine," Fig. 24 (Messrs. James Bertram and Son, Ltd.), on which are made

The "cylinder paper-machine" (Figs. 25 and 26), in which the paper is formed on a revolving cylinder covered with fine wire gauze, was invented by George Dickinson, about 1820. The cylinder (a), is contained in a trough (6), to which the paper pulp is conducted. The water which passes through the wire flows out through the hollow journal (c), whilst the fibres become deposited on the surface of the cylinder. The paper thus formed is removed from the wire by an endless felt (d), which is pressed against the cylinder by the couch roll (e). The cylinder itself therefore forms practically the lower couch roll. To obtain a paper of uniform thickness two or more cylinder machines are usually combined and the wet sheets pressed together. Cylinder machines are mostly used for the manufacture of various thick papers and boards.

Although shaking devices have been proposed for use with cylinder machines, the paper which they yield does not possess the uniform appearance and is not so thoroughly felted as are papers made on the Fourdrinier machine. An interesting form of board machine, consisting of four paper machines, namely, two Fourdrinier and two cylinder machines, one of the latter containing

cylinder machines. For this purpose thin strips of rubber or other material are fixed on the wire of the cylinder so as to divide the web into single sheets.

Grahain's patent cylinder or board machine (Messrs. J. Marx and Co.), which is shown in Fig. 27, differs from the ordinary cylinder machine in that the cylinder (4), does not revolve in a vat; the pulp travels over the apron (7), between the deckle straps (k), on to the cylinder. The preliminary couch roll (f), presses the felt lightly against the stuff and the sheet is taken off from the cylinder by the couch roller (g); it then passes between the

presses the pulp cau: ing it to overflow through the tubes on to a frame, covered with wire gauze, which resembles the hand mould. The water is extracted by suction whilst the mould is shaken laterally and pressed against a couch roll over which an endless felt travels. The sheet is transferred from the mould to this felt and conducted to a wet press. The empty mould is then rinsed and moved back to the pulp distributor.

Machine-made papers which have to be tub sized are either only slightly sized with rosin in the beater, or are made without any addition of size. A solution of glue or gelatine, to which

alum and in some cases soap is added, is used for sizing purposes. The web of paper is run through the size, contained in a trough, the excess being pressed out by rollers. Tub sized papers have to be dried very slowly in order to prevent the size from coming to the surface of the paper and thus making it too hard. For this purpose the paper is conducted over a large number of skeleton cylinders contained in a heated chamber and provided with fans. Special automatic drying machines, as used in drying stained and surface-coated papers, are also applied to this purpose. In many cases it is necessary to rewind the paper carefully before sending it to the printer or before finishing on the calenders. A re

nary calender finish is produced by friction glazing. The "friction calender" used for this purpose consists of one large paper bowl on the top of which revolves at a higher speed a smaller, highly-polished steel bowl. The paper is pressed and smoothed at the same time by means of the friction thus set up, and a very high finish is obtained by this method of glazing.

Although sheet finishing is sometimes done on the ordinary calender, "plate glazing" is more frequently resorted to. In this operation the single sheets are placed between highly polished zinc or copper plates, and pressed between heavy iron bowls. The plates are moved backwards and forwards several times between the

reeling apparatus, by means of which the paper is wound tightly whilst under pressure on a wooden or iron core, is used for this purpose.

The surface of paper as it comes from the paper machine is for many purposes not sufficiently smooth; it has to be finished, either in the web or in single sheets, to suit particular requirements.

The "web glazing," as the former operation is called, consists in passing the web of paper through a calender or calenders in which it is strongly pressed between iron bowls and compressed paper or cotton bowls. Pressure is applied to the bowls by screws and levers or by hydraulic rams. The iron bowls are usually heated by steam.

A finish distinctly different from the ordi

bowls, after which the sheets are removed and again placed between plates for a second pressing.

"Embossing" is another method of calendering by means of which designs are pressed into the surface of the paper. The embossing calender consists of two bowls, one of cotton or paper and the other of steel, upon which the design is engraved.

The cutting of papers lengthways is accomplished by slitter knives such as are used in combination with the paper machine. Special sheet cutters are provided for cutting the web into single sheets. Four or more reels of paper are conducted to one of these machines simultaneously and at a uniform speed. A revolving drum, which carries à knife, cuts the paper once every revolution; the other cutter is a