The Ludlow Typograph is a class of slug-casting machine de signed for the production of display lines. It does not, however, set up matrices, its function being to produce cast slugs from lines of matrices set up by hand in a special composing stick. As each line is set by the compositor the stick containing it is clamped into the machine which produces a solid line of type with the characters in slug form. This particular form of slug casting machine is employed in the main for producing head lines for use in newspaper and periodical work, advertisements and various similar purposes.
Monotype.—The Monotype is a system of mechanical corn position that produces justified lines of single types. It com prises two distinct machines—a keyboard and a caster. The key board has the appearance of an elaborate typewriter. As the operator depresses each key, holes are punched into a strip of paper which automatically travels with each tap of the keys from one spool-holder to another, each letter being represented by its particular combination of perforations. At the end of each line a pointer indicates what special keys should be touched in order to ensure the justification of such line when eventually cast in metal.
When the spool is completed it is placed in position on the casting machine which contains a metal pot, a mould and a matrix holder called the "die case." The latter usually contains 225 matrices arranged in 15 rows of 15 in the compass of a 3-in. square. The perforated strip of paper controls the action of the mechanism which brings the respective matrices into position over the mould in the order desired. When the matrix has been momen tarily clamped into position, a jet of metal is forced into the mould and the type cast. The characters as cast are pushed along until, when the line is completed, they are automatically trans ferred on to a galley. The last line of the spool is the first to be cast, but when each galley is completed the lines will run in cor rect sequence as in the copy. There is an adaptation of the Mono type machine by which rules, ornaments, and a wide range of display type faces may be cast, and afterwards put into cases to be used by the hand compositor.
Machining.—When the forme is sent to press from the corn posing room the printer's work commences. The printer is called a machine-minder in Great Britain, and a pressman in America, and it mainly depends upon him as to whether the work bears the hall mark of "quality" (or otherwise), the printing of the sheets demanding the greatest of care in every stage.
The first operation is to prepare the impression surface (the platen or cylinder) by covering it with a number of sheets of a suitable paper. This is followed by locking the forme securely in
the bed of the machine in a position necessary to the requirements of the particular work in hand. The quoins securing the work in the chase are loosened, and the type "planed down" with a planer, i.e., a smooth flat piece of wood is placed on the type and carefully struck with a mallet to ensure that the "feet" of the type rest solidly on the bed; the quoins are then again tightened and an impression "pulled" on a sheet of paper. Invariably this first pull shows irregularities in the weight of pressure, some parts being so weak that they are unreadable and others so heavy as nearly to cut through the sheet of paper. It is in the rectifica tion of these inequalities that the skill and experience of the machine-minder are exhibited, for unless this work is done with understanding, the printed sheets will appear "patchy" and diffi cult to read. When the printed sheet has been made "readable" the pages are "registered," i.e., placed to print in the proper position on the sheet, and in printing book work, made to "back up" correctly. A well printed book, if the pages are of uniform size, should have the lines on both sides of the leaf printing exactly on the back of each other.
When a forme of type is registered, a sheet is sent to the reader for revision (in case of any letters having been broken off or a word "pied"). While this is taking place, the operation called '"make-ready" is commenced, and it is not unusual for a large forme to take two or even three days to make ready. The desired results are obtained by cutting out on a sheet of thin paper the heavy parts with a sharp knife and "patching up" with paste on the sheet, varying thicknesses of paper on those parts that are weak. When the sheet is completed it is "stuck up" on the im pression surface in a position corresponding exactly with that part of the forme which requires the particular treatment. Another impression is then pulled, and the work of cutting out and patching up is continued until the impressions seen on the back of the sheet present an even and regular appearance. The supply of ink has then to be adjusted so that the requisite amount will be trans ferred to the type in a uniform manner throughout the "run." When printing half-tone work, "interlaying" is often done to ease the pressure on the high lights and to give greater resistance to the solids contained in the plate while printing. "Overlaying" is invariably used when printing illustrations either in monochrome or colour. It is a means of supplying the graduated pressure necessary to ensure that a clean sharp impression of the inked blocks will be made upon the sheet of paper.