FIG. 151.—_Diagram of Cowper and Applegath’s Single Machine._ ]
Each of the machines erected by König for the “Times” printed only one side of the sheet, so that when they had been half printed by one machine, they had then to be passed through the other, in order to be “perfected,” as it is technically termed. These machines were greatly improved by Messrs. Applegath and Cowper, who contrived also a modification by which the sheets could be perfected in one and the same machine. As the principle of these machines has been followed, with more or less diversity of detail, in most of the printing machines at present in use, it is very desirable to lay that principle clearly before the reader. The diagram, Fig. 151, will make the action of Applegath and Cowper’s single-printing machine easily understood. The type is set up on a flat form, A B, which occupies part of the horizontal table, C D, the rest of which, A C, is the inking table. E is a large cylinder, covered with woollen cloth, which forms the “blanket.” The paper passes round this cylinder, and it is pressed against the form. The small black circles, _f_, _g_, _h_, _k_, _l_, _m_, _n_, represent the rollers for distributing the ink. _f_ is called the _ductor_ roller. This roller, which revolves slowly, is made of metal, and parallel to it is a plate of metal, having a perfectly straight edge, nearly, but not quite, touching the cylinder, and at the other side, as well as at the extremities, bent upwards, so as to form a kind of trough, to contain the ink, as a reservoir. The slow rotation of the ductor conveys the ink to the next roller, which is covered with composition, and being made to move backwards and forwards between the ductor roller and the table at certain intervals, it is termed the _vibrating_ roller. The ink having thus reached the inking-table, is spread evenly thereon by the _distributing rollers_, _h_, _k_, and it is taken up from the inking table, as the latter passes under, by the _inking_ rollers, _l_, _m_, _n_. The table, C D, as a whole is constantly moving right and left in a horizontal direction, so that the form passes alternately under the impression cylinder, E, and the inking rollers, _l_, _m_, _n_. The axles of the inking and distributing rollers are made long and slender, and instead of turning in fixed bearings, they rest in slots or notches, in order that, as the form passes below them, they may be raised, so that they rest on the inking slab, and on the types, only by their own weight. They are placed not quite at right angles to the direction of the table, but a little diagonally. The sliding motion caused by this, helps very much in the uniform spreading of the ink. By these arrangements the form is evenly smeared with ink, since each inking roller passes over it _twice_ before it returns to meet the paper under E.