The crank-plate g being driven round in the direction of its arrow, will communicate a see-saw movement to the toothed arc k, next to the toothed wheel l in gearing with it, and an oscillatory motion to the arms m, m, as also to their surmounting pall n. In its swing to the left hand, the catch of the pall will slide over the slope of the teeth of the ratchet wheel o; but in its return to the right hand, it will lay hold of these teeth, and pull them, with their attached drum, round a part of a revolution. The layers of paper in close contact with the under half of the drum will be thus drawn forward at intervals, from the reels, by the friction between its surface and the endless felt, and in lengths corresponding to the arc of vibration of the pall. The knife for cutting these lengths transversely is brought into action at the time when the swing arc is making its inactive stroke, viz., when it is sliding to the left over the slopes of the ratchet teeth o. The extent of this vibration varies according to the distance of the crank stud i, from the centre f, of the plate g, because that distance regulates the extent of the oscillations of the curvilinear rack, and that of the rotation of the drum e, by which the paper is fed forwards to the knife apparatus. The proper length of its several layers being by the above described mechanism carried forward over the bed r of the cutting knife or shears r, v, whose under blade r is fixed, the wiper s, in its revolution with the shaft f, lifts the tail of the lever t, consequently depresses the transverse movable blade v (as shown in [fig. 783.]), and slides the slanting blades across each other obliquely, like a pair of scissors, so as to cause a clean cut across the plies of paper. But just before the shears begin to operate, the transverse board u descends to press the paper with its edge, and hold it fast upon the bed r. During the action of the upper blade v, against the under r, the fall board u, is suspended by a cord passing across pullies from the arm y of the bell-crank lever t, t. Whenever the lifter cam s, has passed away from the tail of the bell-crank t, the weight z, hung upon it, will cause the blade v, and the pinching board u, to be moved up out of the way of the next length of paper, which is regularly brought forward by the rotation of the drum e, as above described. The upper blade of the shears is not set parallel to the shaft of the drum, but obliquely to it, and is, moreover, somewhat curved, so as to close its edge progressively upon that of the fixed blade. The blade v may also be set between two guide pieces, and have the necessary motion given to it by levers.
PAPER-HANGINGS, called more properly by the French, papiers peints. The art of making paper-hangings, papier de tenture, has been copied from the Chinese, among whom it has been practised from time immemorial. The English first imported and began to imitate the Chinese paper-hangings; but being exposed till very lately to a high excise duty upon the manufacture, they have not carried it to that extent and pitch of refinement which the French genius has been enabled to do, unchecked by taxation. The first method of making this paper was stencilling; by laying upon it, in an extended state, a piece of pasteboard having spaces cut out of various figured devices, and applying different water colours with the brush. Another piece of pasteboard with other patterns cut out was next applied, when the former figures were dry, and new designs were thus imparted. By a series of such operations, a tolerable pattern was executed, but with no little labour and expense. The processes of the calico printer were next resorted to, in which engraved blocks of the pear or sycamore were employed to impress the coloured designs.
Paper-hangings may be distinguished into two classes; 1. those which are really painted, and which are designed in France under the title of papiers peints, with brilliant flowers and figures; and 2. those in which the designs are formed by foreign matters applied to the paper, under the name of papier tontisse, or flock paper.
The operations common to paper-hangings, of both kinds, may be stated as follows:—
1. The paper should be well sized.
2. The edges should be evenly cut by an apparatus like the bookbinder’s press.
3. The ends of each of the 24 sheets which form a piece, should be nicely pasted together; or a Fourdrinier web of paper should be taken.
4. Laying the grounds, is done with earthy colours or coloured lakes thickened with size, and applied with brushes.
An expert workman, with one or two children, can lay the grounds of 300 pieces in a day. The pieces are now suspended upon poles near the ceiling, in order to be dried. They are then rolled up and carried to the apartment where they are polished, by being laid upon a smooth table, with the painted side undermost, and rubbed with the polisher. Pieces intended to be satined, are grounded with fine Paris plaster, instead of Spanish white; and are not smoothed with a brass polisher, but with a hard brush attached to the lower end of the swing polishing rod. After spreading the piece upon the table with the grounded side undermost, the paper-stainer dusts the upper surface with finely powdered chalk of Briançon, commonly called talc, and rubs it strongly with the brush. In this way the satiny lustre is produced.
THE PRINTING OPERATIONS.