PRINTING and ENGRAVING (Fa., Imprimerie et Gravure ; GEn., Buchdruckerkun,st und Stecherei).
In the present article, the terms "printing " and "engyaving" will be extended to embrace the following subjects :—Letter-press printing; printing in colours, and chromo-lithography ; type writing ; autographic processes (manifold writers); engraving on wood, eopper, steel, stone, and zinc ; photographic processes (e.g. heliotype, Woodbury-type, Dallas-type, &c., &c.).
Letter-press Printing.—So little change has taken place of late years in the ordinary routine of letter-press printing, that there is no ground for an exhaustive essay on the subject. Progres.s is to be noted exclusively in the perfection of machinery for accomplishing the various objects, and to this branch, attention will be confined. It may be conveniently divided into four sections—composing-machines, printing-presses, flnishing-machines, and cutting-machines.
Composing-rnachines.—One of the most remarkable inventioos in connection with printing in modern times is the Clowes composing-machine, shown in Fig. 1162. It is the invention of John Hooker, a compositor in the employ of Wrn. Clowes & Sons, Limited, of London and Beecles, and is in a certain degree based upon Mitchell's composing-machine exhibited in 1862. The machine is triangular, the sides measuring 5 ft., 5 ft., and 7 ft., the base forming the front. The table a is about 3 ft. above the floor ; over it, travel a number (48) of endless tapes b, from the back towards a collecting-tape e passing from left to right. Over each of the tapes b, is a trough d filled with types lying on their sides, feet foremost. At the bottom of each trough d, is a little stop, on which the types rest ; and just above it, on one side, is a knife or striker in communication with an armatnre. Electricity is provided by a couple of Grove's cells, or otherwise, and a series of wires conneots tho eloctro-magnet of each Armature with the " setting-board," to be presently described. When the electrio circuit is complete, the armature is attracted to its electro-magnet, and the striker pushea the lowermost type out of the trough upon the tape b immediately below it, by which it la oonveyed to the collecting-tape c. The tapes b are driven by power at the rate of 7 in. a second, and the tape c at 21i in. ; the relative positions and speeds of the tapes b and c are so adjusted that each type °hall unerringly pastime the position corresponding to the order required by the matter to be printed. The setting-board e ia placed in a convenient position for the compositor. It is divided into a aeriea of copper dins describing the form of the receptaclea of an ordinary lower cam; each disc la connected by a wire with the electro-magnet of the letter indicated, while a second wire from the oppoaite pole of the battery terminatee in a copper stylus, which ia held by the compositor. Composition is effected by tapping with the atylas upon each disc in succession, according to the lettera required ; and as contact with any portion of a disc suffices to establish the circuit and bring down a type, while the area of the setting-board ia only about 12 in. by 6 in., the process is exceedingly rapid. The setting-board does not embrace every
letter and aign ; those of rare occurrence are omitted, and a aupply of them is kept in a small case f at the compositor's left hand, so that he can readily aelect them and get them into place by means of a little spout provided for the purpose over a spare tape. The composed matter forms one continuous line, which is removed at intervals and justified. Into thia line, only one type can enter at a time ; iu came of any derangement or obstruction, a lever breaka the connection, and the machine is arreated till it has been rectified. The effective capacity of thia machine amounts to 10,000 typea hourly set up in page form, employing four lads setting, justifying, and replenishing the type-trougha. Only one fount can be used at a time, but the machine is adapted to take 1 or 5 different founts by aimply exchanging the type& Printing-Presses.—In the article "Presa" in Spans' Dictionary of Engineering,' pp. 2660-2670, will be found detailed descriptions and illustrations of the moat notable improvements in printing preans up to that date. Since then, the following has been introduced :— Ingram's.—Thia is a web rotary machine, invented for printing illustrated newspapers, and used for the Illustrated London News and other papers issued from the same office. It is the invention of W. J. Ingram, and is made by Middleton & Co., Loman Street, Southwark. It is illustrated in aection in Fig. 1163: A is the roll of paper, containing a length of 2-3 milea ; B, the type- and impression-cylinders for printing the inner forme, or type-side of the paper ; C, calendering- or smoothing-rollers, to remove the indentations produoed by the impression of B, so that a smooth surface is preeerved to receive the outer forme, or illustrated side of the paper, which is printed by D ; E, cylindere, one provided with a saw-toothed knife, and the other with a corresponding indentation, to perforate the paper between each impression ; F, rollera for holding the paper securely, to resist the effect of G, which are called anatching-rollers, and, being driven at a rather higher surfae,e-speed than the holding-rollere, anatch or break the paper at the places where it has boen perfomted, and form it into separate sheets. As it is found that machinery for folding newspapers works much better at a moderate speed, in this ease, it has been arranged in duplicate, so that each folder only works at half the speed of the printing-machine. The vibrating arm II delivers the sheets alternately to K and J, which are carrying-tapes leading to the two folding-machines. If the sheets are wanted unfolded, the asm II is moved to its highest position, and there fixed ; it then delivers the sheets to the roller L, and, by means of a blast of air and a flier, they aro laid in a pilo on a table provided for thern. This change can be rnade without stopping tho machine. The dotted lino from A to L indicates the course of the paper throngh the machine. The effective capacity is 6500 eopies printed and folded per hour. This tnachine has proved so superior for all illustrated work tbat it is coming into uso among first-class general printers.