The frame supporting the feeding-board, P, consists of two rails X, fitted upon the axis of the platen, and sup ported at the opposite ends by a brace from the framing; they sustain the pivots of the wheels, d, d, for the chains ; x are two rulers fixed at each side of the feeding-board, and forming a lodgment for the ends of the ruler 2, which is attached to the blanket, and it slides upon these when it is advanced by the chains. The spaces on the platen between the segments i, i, are all filled up by pieces of wood, ex cept one, and in this space the ruler is received when it passes through the machine. In the interval when the spaces between the types are passing over the sheet, and therefore leave the margin between the pages of printing, the paper is not held between the rollers ; but to prevent it from slipping during this interval, the blanket and paper are pressed down upon the pieces of wood which fill up in the platen between the segments, i, i, by the weight of small rollers or wires, 4. supported by cocks, 5, projecting from the axis of the prism, and being fitted into the slits at the end. of these cocks.
Many adjustments are required to make it work cor rectly. The segments, i, i, upon the platen roller are attached to the central axis, I, by three screws at each end; the two middle ones of these (represented with square heads) draw the segments down upon the central axis, whilst the others (which are turned by a screw driver) bear them off; therefore, by means of these screws, the segments can be accurately adjusted. To render the whole impression greater or less, the screws, 3, beneath the bear ings of the platen roller, are turned as before mentioned. The degree of pressure with which the ink roller hears upon the types, is regulated by increasing or diminishing the size of the shapes, if, which support its weight. And to render these capable of adjustment, each is composed of four pieces, marked 6, attached by screws, 7, to a central piece or wheel, which is fixed upon the axis ; and as the edges of these pieces form the outline of the shape, they admit of being adjusted by other screws to a greater or less distance from the centre, and of course may be made to bear up the ink cylinder, till the pressure on the types is equal throughout the whole surface, and sufficient to supply the ink properly. The ink cylinder is adjustable as to its pressure against the dish ihuting roller, and for this purpose the bearings, k, which support the cylinder, are fitted upon the pieces, L, to slide, being capable of regulation by means of screws. In a similar manner the distributing roller can be adjusted to a proper distance from the inking cylinder. The plate, o, can be adjusted for the distance
from the ink roller, N, by screws, p, fastened by thumb nuts : behind the inking cylinder, K, a rubber or scraper, is placed, to press very lightly against the cylinder, and to prevent the ink accumulating in rings round the cylinder. It is necessary that the wheels D and E should be placed upon their axes, in such a position that their curvature will correspond with the curvature of the prism and platen. For this purpose the universal joint, R, is fitted upon the axis, 1, of the wheel, with a round part, that it may turn on it. A piece of metal, r, is fixed fast upon the spindle, 1, and has a hole in it for the reception of a tooth, s, which is screwed fast upon the universal joint; then two screws being tapped through the sides of the piece r, press upon the end of s, and by forcing it either way, will adjust the wheel with respect to the platen, till they exactly corres pond.
The manner of forming the inking and distributing rollers with an elastic substance, is worthy of notice. After many trials, a composition of glue, mixed with treacle, was found to answer. The roller is made of a copper tube, covered with canvass, and placed in a mould, which is a cylindrical metal tube, accurately bored, and oiled inside ; the melted composition is then poured into the space of the mould, and when cold, the whole is drawn out of it, with the glue adhering to the copper tube, and forming an accu rate cylinder. The composition will not harden by expo sure to air, nor does it dissolve by the oil contained in the ink.* Steam Printing Machine.
Mr. Koenig, from Saxony, seems to have been the first person who conceived the idea of constructing a steam printing machine. Having failed in interesting the conti nental printers in his views, he came to London about 1804; and after many years of experiment and disappoint ment, he at last succeeded in erecting two machines for printing the Times newspaper, which was first printed by them on the 20th Nov. 1814. He afterwards erected another for Mr. R. Taylor, in Shoe Lane; one for Messrs. Bensley, which printed both sides of the sheet in succes sion, and another for the same house, which printed both sides of the sheet at once.
As this machine, however, was very complicated, many mechanics attempted to simplify it. This great object was soon accomplished by Mr. Dryden, who, under the direction of Messrs. Applegath and Cowper, constructed two ma chines for Messrs. Bensley, one double and the other single. The double machine throws off from 800 to 1000 sheets, printed on both sides, in an hour ; and the single one from 1500 to 1600 printed on one side.