An inking-apparatus is placed at each end of the table al, N, which carries the types C, D, and which traverses backwards and forwards under the printing-cylinders a, LI, and inking-rollers. The ink, received from a reservoir k by the two rollers 1 and 'la, is transferred from them to the surface of the table ; the surface of the table inks the rollers n, 0, and these, in their turn, ink the types as they pass backwards and forwards for each impression. The excellence of the printing depends in a great measure on the types being properly inked. In a machine arranged according to the accompanying diagram, the types are touched four times by the inking-rollers for each impression, and by increasing the number of rollers, any perfection of inking may be obtained. The machines commonly used for printing books will print from seven hundred to one thousand per hour, in perfect register ; and for news papers printed on one side only, from four thousand to six thousand per hour.
Steam-power has also been applied to flat machines, which are a modification of the Stanhope press, in which the table, with a form of type at each end, moves backwards and forwards under the platen, which gives the impression to one form while the other is being inked by the rollers. This description of press was for a time supposed to be best adapted for the finer sorts of bookwork; but the process was very much slower, and the belief in their superiority of work was not universally admitted. Cylindrical machines were frequently used, not only for newspapers, where rapidity of production was required, but for books containing engravings on wood, where excellence of work manship was demanded. Several of theie machines were exhibited at the Paris Universal Exhibition in 1855, the French printers having devoted much attention to the improvement of cylindrical machines. In his report as juryman on `Class XXVI.—Drawing and Modelling, Letter-press and Copper-plate Printing, and Photography;' Mr. Charles Knight says, " In the Paris Exhibition, several machines, offering the advantage of more perfect inking, and of preventing what is called setting-off' [that is, the sheet becoming blurred by the moist ink being pressed upon], showed that the attention of the French printers had been mere directed than with us to the practicability of producing the finest work by the machine instead of by the hand-press. Some of our artists, who have watched the dependence of the wood-engraver on the printer, have long been of opinion that the equal operation of the cylinder is superior to the irregular force of the hand-press. But the heads of our printing establishments have generally considered that the cylindrical machine was only calculated to save labour, and not to produce fine work. Our machine-makers have, therefore, made various
labour-saving machines upon the principle of flat pressure, which, as it is the principle of the hand-press, at which the moat expensive work was produced, was thought to be the only principle for a more perfect machine. The French, on the contrary, have turned their attention to the perfection of the cylindrical machine, knowing that it had natural advantages which could not be obtained by flat pressure. When a sheet of paper is brought into contact with an inked surface of types, by being laid flat upon that surface, a large body of air has to be expelled by the heavy platen, operating at once upon the whole sur face. The cylinder, on the contrary, touches the type, and produces the impression on the paper, line by line, and there is no atmospheric resistance to be overcome. The French printers have, therefore, sought for the improvement of the cylindrical machine. The single cylinder machine of 31. Dutartre produces work which cannot be excelled by the most careful operations of the press. It prints only on one side [the process having to be repeated to ' perfect ' the sheet]; and the form passes under a double set of inking-rollers, at each end of the table, before it receives the impression. In the double-cylinder machine of the same inventor, a waste sheet of paper is interposed so as to prevent setting-off; and thus both sides of the paper may be printed at once, without leaving that blurred impression of one side which so commonly disfigures machine-printing. The French printers now do their finest work by the cylindrical machine, and much of their common work by the hand-press." The report goes on to say that, on the whole, the average work of the French printers is superior to that of the English. It attributes this partly to the better quality of their paper, which is farther improved 'by being passed through powerful rollers, thus creating a more even surface, partly by using dry paper instead of wet, partly by the use of silk instead of parchment for tym pana in their hand-presses and flat-pressure machines ; and other little niceties, the results of long practice based upon scientific investigation. M. Dutartree double-cylinder machine has been introduced into England ; and a patent has been taken out for an improvement in the manufacture of paper, by which the necessity of wetting it to enable it to receive the ink will be removed : we believe, as far as this experi ment has been carried out, that it has been successful.