The Monotype was invented by Tolbert Lanston, who was born in the US in 1844. It consists of two units: a keyboard and a casting machine. The keyboard is operated by a compositor, while the caster attendant is - or should be - a skilled technicial with a full knowledge of type and a flair for turning out the
maximum production with the minimum of trouble to the hand compositor who
will subsequently handle and correct the type.
Monotype composition rests on a mathematical underpinning called the Unit System. Under this system every characters has its "unit value" which it shares with the other characters in its row of the matrix case. The basic "unit" in the system is 1/18 of a standard printer's "point" (the basic "unit" is standardized as .0007685 inches; 12 points is standardized as .1660 inches). From this basic unit, all character widths for every point size in the Monotype system are determined.
Unlike a Linotype operator, the Monotype operator on this keyboard sees nothing of the matrices or the casting. His finished product is a spool of paper perforated with small holes like a piano roll. This spool of paper is next taken to the casting unit where, under the supervision of the caster attendant, it functions as the vital link in producing the thousands of individual letters and spaces in the form of justified lines of type.
Before setting commences, a spool of new paper is placed in position above the keyboard. This spool has a line of guiding holes at each side for winding purposes. The measure of the job is set on the "em" scale of the keyboard.
As typing or keyboarding proceeds, a pointer moves along the em scale. When approaching the end of the line measure a bell rings to warn the operator, who then quickly decides where to end the line. Each character or space in the line is a definite number of units in width and the units are registered, or "added," as the line proceeds. In ordinary composition the space between the words is first registered as four units, but when the last word of the line is keyed the remaining space is divided equally and added to the four-unit spaces -- or "variables," as they are termed -- in order to fill out and justify the line to the measure. All this is done automatically by means of the justification scale or drum. The operator simply notes the two numbers indicated on the drum by the pointer (anything from 1 to 15) and taps the corresponding keys on the two rows of red keys (numbered 1 to 15) at the top of the keyboard. He then presses a reversing key at the bottom of the keyboard, which moves the em rack pointer over to the left, ready for commencing the next line.
As each key button is depressed the spool of paper is perforated -- usually by one or more punches. When the key is released the paper moves one marginal hole, ready for the next perforations. These perforations will control the position of the matrix case over the mold when casting and also control the set width of every character and space, the starting and stopping of the pump, and the movement of the completed line of type to the galley.
The caster's main mechanism is mounted on a heavy base, and includes the mold, matrix case, paper tower with air pipes leading to the pin blocks which govern the positioning of the matrix over the mold, a wedge which gives each type character its correct width and two further wedges -- one coarse, one fine -- for controlling the width of the spaces between the words so that the lines are justified correctly.
Before casting from the spool, the attendant places the correct mold and type-sizing wedge on the machine, replaces the bridge over the mold and inserts the correct matrix case in proper position. The melting pot of molten Monotype metal is swung round and raised until the nozzle of the pump fits in the orifice under the mold. An em quad (18 units) is cast and sized up with the aid of a micrometer. The horizontal and vertical alignments are then adjusted, the measure is set to receive the lines, a galley is fixed, and casting commences.
The spool starts on the caster where the keyboard operator finished. Therefore, the two perforations for justifying the line come first. As on the keyboard, the paper travels one marginal hole per character. The first two revolutions of the machine are concerned with positioning the two wedges to give the correct space between the words in the line that follows. The pump is automatically engaged and the compostion now commences with the last letter of the line and so on until the next two justifying perforations, which also cause the completed line to be drawn from the type channel and pushed into the galley opening.