ribs. They are next pushed still farther towards the right of the
machine into a box having ribs engaging the notches in the side of
the matrices, but with downwardly inclined grooves crossing these
ribs, by which the shoulder sat the upper end of the space bars
are allowed to descend, and
the spaces are thus dropped
out of line and fall through
a chute into the space-box
from which they originally
came. The matrices are
pushed still farther to the
right, where their teeth
slide along the distributor
bar T, being carried by
two screws which engage
opposite sides of the matrices
and keep them separated
so that they hang
loosely from the distributor
bar. The ribs of the
distributor bar are so arranged
as to support each
matrix by one or more
pairs of teeth until it
arrives opposite the mouth
of its own magazine channel,
where they are interrupted
in such a manner that the matrix is unsupported and drops
into the magazine for further use. It will thus be apparent that
there is a constant circulation of the matrices through the machine,
and the composing of one line, the casting of another and the distribution
of a third are all carried on at the same time, which adds greatly
to the speed of the operation. The machine may be fitted with double
magazine, which with double-letter matrices gives 360 characters
or four faces ready for use, or even with three magazines, which
provide for 540 characters or six faces, the movement of a hand
lever bringing the desired magazine into use.
 |
| |
| Fig. 10.—Line of Matrices with Spaces. | Fig. 11.—Perforated Strip. |
Lanston Monotype.—In the Lanston apparatus there are two distinct machines, a ribbon-punching machine and a type-casting and composing machine. The first of these is a small device resembling a typewriter, having a number of keys, 257 in all, corresponding to all the characters used in a fount of type, with some additions representing certain movements to be performed by the composing machine. These keys, when depressed, admit compressed air to a plunger or combination of two plungers working punches, whereby perforations are made in a strip of paper fed step by step through the machine. Most of the keys make two perforations, though some a single one only. These perforations stand in a transverse line across the strip, as shown in fig. 11, and their relative position in the line varies with the particular key operated. At the end of each word a spacing key is struck, and suitable perforations are made in the strip, and as the end of a line is neared, a bell rings to warn the operator, who, by looking at a line scale facing him on the machine, is enabled to see how many units of space remain to be filled, and can then determine whether another word or syllable can be set up. If not, it then becomes necessary to provide proper space-type to justify or fill out the line, which is done by increasing the width of the normal space-types already provided for in the proportion which the number of units of space still vacant in the line bears to the number of space-types which the line contains. For example, if there are ten space-types and 110 of an inch of space remains to be filled, each space-type must be increased in thickness just 1100 of an inch completely to fill the line. It is not necessary, however, for the operator to make this calculation, for he has only to consult the scale provided for this purpose, and is referred at once to the proper keys to punch the justifying perforations in the strip. Each time the space key is depressed a pointer rises one step against a cylindrical scale placed vertically in front of the machine, and when the operator has finished setting a line he presses a special key which causes the cylinder to rotate until it automatically stops with the required number at the end of the pointer. This number is in the form 34, and to complete the justification of the line the operator has only to depress the appropriate keys in the top two rows of the keyboard, in this case No. 3 of the top row and No. 4 of the second.
The ribbon thus prepared in the punching machine is used to control all the movements of the casting or composing machine. The matrices for making the type faces are formed in a plate about 3 in. square, and any character is brought opposite the casting point by the movement of the matrix-carrier in two directions, or rather by the resultant of two such independent movements. As the perforations for controlling the galley movements and those for justifying the line are necessarily made after the others in the perforating machine, and these operations must be provided for in the composing machine before the line is set up, the latter machine is so organized that the ribbon is passed through and the types are set in the reverse order to that in which the strip was punched. The perforated ribbon is wound from one wheel off to another, passing over the edge of a tracker board in which there are a number of holes corresponding to those which may occur in the ribbon, and each of these holes communicates by a tube with a small piston which controls some device for performing one of the various operations of the machine. As the ribbon passes over the tracker board, a jet of compressed air passes to the appropriate operating device whenever a ribbon perforation or any combination of them coincides with the proper holes. The two perforations on each transverse line control two stop pins which limit the movements of the matrix carrier to bringing the proper matrix to the casting-point, while the justifying perforations set in motion devices which open the space mould to cast space type of the exact size to effect the proper justification of the line, and the galley perforation starts the feeding device which moves the galley for the next line of type. The matrix-carrier may be readily removed and another carrying a different style or size of type substituted therefor.
In modern printing it is often the case that the printing surface actually used in the press (see Printing) is not the original forme of type, whether consisting of separate type set up by machine or by hand, or of Linotype slugs, but a reproduction of it made by electrotyping or by stereotyping. Of these two processes the former is the slower and the more costly, but it produces the better results, since electrotypes plates are capable of yielding a larger number of sharp impressions than are stereotypes.
Electrotyping.—In making an electrotype, a moulding composition consisting mainly of wax with a little black lead, is poured when molten into a shallow metal tray, and, when it has set, its surface is brushed over with black lead and polished. An impression of the forme, which is also black leaded, is next taken in the wax while it is still warm, often by the aid of a hydraulic press, and the mould thus obtained, after being separated from the forme, undergoes a process of building up, which consists of dropping heated-wax upon those portions which require to be more deeply sunk in the finished type, that is, upon those places where “whites” are to appear in the print. The face of the finished mould is then carefully covered with black lead, which is a conductor of electricity, and the whole is immersed in an electrotyping bath, where copper is deposited on the black leaded portions by means of the current from a Smee’s battery or a dynamo machine. When the deposit, or shell, is sufficiently thick, it is disengaged from the wax mould, backed with a metal which resembles type-metal but contains a larger proportion of lead, and trimmed and planed. For use in rotary presses curved electrotypes may be produced.
Stereotyping.—The great advantage of stereotyping is in connexion with the production of newspapers, where the desideratum is the printing off of a large number of copies in a short time. For this purpose, in the first place, rotary machines must be employed, and stereotyping affords a ready means of obtaining curved printing surfaces to fit their cylinders. It is true that stereotyping is not absolutely necessary for rotary printing, since it has been found possible to print from movable type clamped on the cylinders in curved frames known as “turtles.” But to set up duplicate formes of type is impracticable, and, therefore, this device does not permit the utilization of more than one press. Herein lies the second great advantage of stereotyping, for it enables the printer to obtain as many replicas of each forme as he desires, and thus not only to employ a number of machines simultaneously, but also to “dress” each of them with several duplicates of the same forme, as is required in the later developments of high-speed presses.
The first attempt at making stereotypes was by means of moist clay into which, after it had been impressed with the type and baked, molten type metal was poured; but this method did not yield a curved plate. Later the clay was replaced by papier-mâché, which being flexible can be bent to the required shape. This papier-maché, known as flong and composed of several sheets of paper united by a paste capable of withstanding a high temperature without burning, is moistened and laid over the forme of type, into which it is well pressed either by beating with a long-handled brush or, according to the more modern and expeditious method, by being
passed through a moulding press. The flong is next dried, for which