Finishing-machines.—Gill's rolling- and flnishing-machine, made by Furnival & Co., 1VIanchester, is in almoet universal use among English printers. The latest improved form is shown in Fig. 116,1. Tbe printed sheets are fed from the table a by means of endless carrying-tapes b, between two rolls c, which are hollow, so as to receive steam, when it is desired to hot-roll the paper. The passage between the rolls gives a polished surface to each side of the paper. The finished sheets are delivered hy another endless tape d to a table. An indiarubber " doctor " or scraper cleanses the faoes of the rolls from any possible adhesion of ink after each sheet bas passed through.
Cutting-machines.—One of the most improved " guillotines,' or paper-cutting machines is that invented by Salmon & Capper, Manchester, and shown in Figs. 1165-6 : A is the side frames ; a, wheel with crank for giving motion to the kniM-bar; b, knife-bar, with diagonal slots, to give the lateral movement as it descends ; b', parts of tbe rods between the knife-bar and beam ; c, slotted link, jointed to the upper edge of b ; d, clamping-plate, bearing a bowl d' upon a stud, and a second bowl d2 at the haek. One end of the screwed rod e is jointed to a projection c' from the link c, the other end sliding through a hole in a swivel-piece e' , having pivots carried by brackets bolted to the end of the knife-bar. A steel spring e2 is placed upon the screwed bar, abutting against the swivel-piece at one end, and against screw-nuts ea at the other. When the knife-bar b descends, and the clamp d comes upon the paper to be cut, its descent is arrested, and as the knife bar continues its downward movement, the bowl d' in the clamp remains stationary, acts upon the slotted link c, and causes it to assume a greater or less angle, according to the thickness of the paper being cut.
Printing in Colours, and Chromo-lithography.—Printing in colours as usually effected requires a separate impression to be taken for each colour, as great difficulty is experienced in combining the pigments for a polychrome print so as to complete the operation by one impression, on account of their varying densities and consistencies. W. G. White claims to have overcome the obstacle, and to have developed a process which is said to be in use on an extensive scale in Paris. His method, so far as divulged, is as follows. The prepared pigment chosen for the ground of the design is first run into a mould, so as to form a solid block about 3 in. thick. The pattern is traced with a steel point upon a sheet of " artificial talc," made from a mixture of collodion and oil, and this is pressed upon the block, so as to leave an impression of the lines upon its surface. The pattern
is then cut out of the block by a sharp steel knife mounted on the end of an articulated parallelo gram, so as to be maintained in a vertical position, while at the same time having a perfectly free horizontal motion. The various pigments forming the designs are then poured into the spaces cut out, a kind of mould being formed temporarily by a portion of the ground colour, supplemented by strips of wood soaked in water. The paint is poured in hot and liquid, and, as soon as it has cooled, another is added, and so on, until the whole design is finished, thus forming a complete mosaic. In the case of a large subject, various portions of the block may be executed by different operators at once, and then joined together ; the method is also being tried of cutting out the whole pattern in wood or nietal, by means of a band-saw, and then forcing the die so formed into the block of ground colour, so as to stamp out the colour therefrom. The mosaic, or " type," as it is called, is put into a powerful press, resembling that used by lithographers, and is first shaved by a heavy steel knife, so as to render the surface perfectly even and smooth. The material to be printed upon is then laid face downwards on the slightly moistened block, and a series of rollers are passed ever it once or twice, when the impression is found to have completely penetratod its substance.
The print is exposed for a few seconds to the heat of a hot plate, for driving off the solvents employed, and perhaps fixing the colours, which are printed so permanently as to vrithstand exposure to the sun, and whon a piece of velvet printed in this manner was boiled for 8 hours in strong potash solution, the colour did not entirely disappear. Water-colour drawings and oil paintings may be reproduced by this process, so as to present the appearance of chrome-lithographs and olcographe respectively. But it is stated to have a far more extended application, in printing upon textile fabrics the designs of Gobelins and Arbusson tapestry, to form curtains, portieres, &a The range of materials capable of being treated appears to be extensive, as the same design has been reproduced upon fine silk and the coarsest jute sacking, both impressions, it is said, presenting all the neeessary sharpness of outline.