Linotype machine

The Linotype machine (pronounced "Line-O-Type" ['laɪnəˌtaɪp]) is a "line casting" machine used in printing. The Linotype machine operator enters text on a 90-character keyboard. The machine assembles "matrices", which are molds for the letter forms, into a line. The assembled line is then cast as a single piece, called a "slug", of type metal. The matrices are then returned to the type magazine from which they came.

The name of the machine comes from the fact that it produces an entire line of metal type at once - hence a 'line o' type'. This allows much faster typesetting and composition than the original hand composition developed by Gutenberg, in which operators place down one pre-cast metal letter, punctuation mark or space at a time. The machine revolutionized newspaper publishing, making it possible for a relatively small number of operators to set type for many pages on a daily basis.


In 1884, a German clock maker, Ottmar Mergenthaler, who had emigrated to America in 1872, conceived the idea of assembling metallic letter molds, called matrices, and casting molten metal into them, all within a single machine. His first attempt proved the idea feasible, and a new company was formed. Always improving his invention, Mergenthaler further developed his idea of an independent matrix machine. In July, 1886, the first commercially used Linotype was installed in the printing office of the New York Tribune. Here it was immediately used on the daily paper and a large book. The book, the first ever composed with the new Linotype method, was titled, The Tribune Book of Open-Air Sports.

Initially, The Mergenthaler Linotype Company was the only company producing linecasting machines, but in time, other companies would begin manufacturing. The Intertype Company, which produced the Intertype, a machine closely resembling the Linotype, and using the same matrices as the Linotype, started production around 1914. Where Mergenthaler prided themselves on intricately formed cast-iron parts on their machine, Intertype machined many of their similar parts from steel and aluminum.

Linotype machines can still be found in operation today, composing as they have done for well over 100 years, producing printing slugs for use together with handset type, in small job shops, and newspaper museums throughout the world.


The distinguishing characteristic of a Linotype machine is that it casts "slugs" which contain the text for a complete line. The molds used for this are called "matrices".

Each matrix contains the letter form for a single character of a font of type, i.e., a particular type design in a particular size. The letter form is engraved into one side of the matrix. For sizes up to 14 points, and in some matrices of size 16 to 24 points, the matrix has two letter forms on it, the upright ("Roman") and the slanted ("Italic") form of a given character. The machine operator can select which of the two will be cast by operating the "auxiliary rail" of the "assembler". This is the origin of the old typesetting terms "upper rail" for italic and "lower rail" for roman characters. These terms persisted in phototypesetting technology even though the mechanics of the auxiliary rail do not exist there.

Overview of machine operation

The Linotype machine consists of four major sections:

  1. Magazine
  2. Keyboard
  3. Casting mechanism
  4. Distribution mechanism

The operator interacts with the machine via the keyboard, composing lines of text. The other sections are automatic; they start as soon as a line is completely composed.

Magazine section

The magazine section is the part of the machine where the matrices are held when not in use, and released as the operator touches keys on the keyboard. The magazine is a flat box with vertical separators that form "channels", one channel for each character in the font. Most magazines have 90 channels, but some may have fewer, for example for large type sizes.

The magazine holds a particular font of type, i.e., a particular type design in a particular size. If a different size or style was needed, the operator would switch to a different magazine. Many models of the Linotype machine could keep several magazines (as many as four) available at a time. In some of these, the operator could shift to a different magazine by raising or lowering the stack of magazines with a crank. Such machines would not allow mixing fonts within a single line. Others, such as the Model 9, allowed arbitrary mixing of text from up to four magazines within a single line.


In a Linotype machine, the term "escapements" refers to the mechanisms at the bottom of the magazine that releases matrices one at a time as keys are pressed on the keyboard. There is an escapement for each channel in the magazine.

Keyboard and composing section

In the composing section, the operator enters the text for a line on the keyboard. Each keystroke releases a matrix from the "magazine" mounted above the keyboard. The matrix travels through channels to the "assembler" where the matrices are lined up side by side in the order they were released.

When a space is needed, the operator touches the "spaceband lever" just to the left of the keyboard. This releases a "spaceband" from the spaceband box. Spacebands are stored separately from the matrices because they are too big to fit in the magazine.

Once enough text has been entered for the line, the operator depresses the "casting lever" mounted on the front right corner of the keyboard. This lifts the completed line in the assembler into the casting section of the machine and engages the clutch that drives the casting and distribution sections. The operator is now finished with the line; the remaining processing is automatic. While the line is being cast, the operator can continue entering text for the next line.

Matrices for type sizes smaller than 24 points usually have two characters on them. For letters and digits, they are normally the roman (upright) and italic (slanted) forms. If the matrix sits all the way down in the assembler, the roman character will be cast. A horizontal rail in the assembler can be pushed in by the operator; this will hold the matrices somewhat higher, and the italic character will be cast. The rail can be pushed in and out during the composing of a line if mixed roman and italic text is needed. This is the origin of the terms "lower rail" for roman and "upper rail" for italic text. These terms are now obsolete but were common even after phototypesetting had displaced the Linotype machine.


The keyboard has 90 keys. There is no shift key; uppercase letters have keys separate from the lowercase letters. The arrangement of letters corresponds roughly to letter frequency, with the most frequently used letters on the left.

The first two vertical rows of keys are "etaoin" and "shrdlu". A Linotype operator would often deal with a typing error by running the fingers down these two rows, thus filling out the line with the nonsense words etaoin shrdlu. This is known as a run down. It is often quicker to cast a bad slug than to hand-correct the line within the assembler. The slug with the run down is removed once it has been cast, or by the proofreader.

The Linotype keyboard has the same alphabet arrangement given twice, once for lower-case letters, the keys in black, on the left side of the keyboard, and once for upper-case letters, the keys in white, located on the right side of the keyboard. The blue keys in the middle are punctuation, numbers, and fixed width spaces. In proper keyboard operation, the experienced operator's left hand operates only the spaceband key and the left vertical row of keys. The operator's right hand strokes the remaining keys on the entire keyboard.

The keys of the keyboard are connected via vertical pushrods to the escapements. When a key is pressed, the corresponding escapement is actuated, which releases a matrix from the magazine. With one exception, each key corresponds directly to a channel in the standard ("90 channel") magazine. The one exception is the lower-case letter "e": that letter is used so often that the "90 channel" magazine actually has 91 channels, with two channels (the leftmost two) both used for the letter "e". Similarly, the "72 channel" magazine actually has 73 channels, with the leftmost two being used for lower-case "e". Consecutive keystrokes on the "e" key release matrices alternately from the two "e" channels in the magazine.

On machines that support multiple magazines, there is a shifting mechanism that controls which magazine is currently connected to the keyboard. In most machines, this is done by raising or lowering the stack of magazines.

Spaceband box

In justified text, the spaces are not fixed width; they expand to make all lines equal in width. In Linotype machines this is done by spacebands. A spaceband consists of two wedges, one similar in size and shape to a type matrix, one with a long tail. The wide part of the wedge is at the bottom of the tail, so pushing the tail up expands the spaceband.

Spacebands are not held in the magazine due to their size. Instead, they are held in a spaceband box and released one at a time by pressing the spaceband lever at the left edge of the keyboard.


Matrices released from the magazine, and spacebands released from the spaceband box, drop down into the assembler. This is a rail that holds the matrices and spacebands, with a jaw on the left end set to the desired line width. When the operator judges that the line is close enough to full, he raises the casting lever on the bottom of the keyboard to send the line to the casting section of the Linotype machine. The remaining processing for that line is automatic; as soon as the finished line has been transferred to the casting section, the operator can begin composing the next line of text.

Casting section

The casting section receives completed lines from the assembler, and uses these to cast the type slugs that are the product of the Linotype machine. The casting section is automatic: once it is activated by the operator sending a completed line by raising the casting lever, a series of cams and levers move the matrices through the casting section and control the sequence of steps that produce the slug.


From the assembler, the assembled line moves via the first elevator to the justification vise. The vise has two jaws (1 and 2 in the illustration) which are set to the desired line width. The spacebands are now expanded to justify the line. When the line is justified, the matrices fit tightly between the vise jaws, forming a tight seal which will prevent the molten type metal from escaping when the line is cast.

Justification is done by a spring loaded ram (5) which raises the tails of the spacebands.

If the operator did not assemble enough characters, the line will not justify correctly: even with the spacebands expanded all the way, the matrices are not tight. A safety mechanism in the justification vise detects this and blocks the casting operation. Without such a mechanism, the result would be a squirt of molten type metal spraying out through the gaps between the matrices, creating a time consuming mess and a possible hazard to the operator. If a squirt did occur, it was generally up to the operator to grab the "hell bucket" and catch the flowing lead. It was so called because the bucket would often "go to hell" or melt while holding the molten lead that was still extremely hot at the time. Also, in conjunction with possible hazards facing an operator, toxic lead fumes should be noted as they were the result of melting the lead ingots for casting.

Mold disk and pot

The justification vise holds the assembled line against the face of the mold disk. The mold disk has rectangular openings which correspond to the width and thickness of the slugs (cast lines) to be made. Mold liners fit into these openings for specific slug dimensions.

Behind the mold disk is the type metal pot, which contains molten type metal. A piston in the pot pushes the molten metal down into the pot, which forces the metal through the pot throat and into the mold, forcing it against the faces of the matrices. These have character shapes cut into them, so the result is a cast slug with the character shapes of the line on its front face. The mold disk is water-cooled to carry away the heat of the molten type metal and allow the cast slugs to solidify quickly.

When casting is complete, the mold disk turns a quarter turn to the ejector and knife block assembly. The ejector is a rectangular rod that pushes the completed slug from the mold aperture in the mold disk. As it emerges from the mold disk, the slug passes a set of knife edges in the knife block, which trims off any small irregularities in the casting and produces a slug of exactly the desired width and height. From there, the slug drops into the galley tray which holds the lines in the order in which they were cast.

Distribution mechanism

The most significant innovation in the Linotype machine was that it automated the distribution step, i.e., returning the matrices and space bands back to the correct place in their respective magazines. This is done by the distributor.

After casting is completed, the matrices are pushed to the second elevator which raises them to the distributor at the top of the magazine. The space bands are separated out at this point and are returned to the spaceband box.

The matrices have a pattern of teeth at the top, by which they hang from the distributor bar. Some of the teeth are cut away; which pattern of teeth is cut away depends on the character on the matrix, i.e., which channel in the magazine it belongs in. Similarly, teeth are cut away along portions of the distributor bar. The bar on the elevator has all teeth, so it will hold any matrix (but not the space bands, which have no teeth at all).

Distributor bar and matrix teeth coding

As the matrices are carried along the distributor bar by the distributor screws, they will hang on only so long as there are teeth to hold them. As soon as the matrix reaches the point where each of its teeth corresponds to a cut-away tooth on the distributor bar, it is no longer supported and will drop into the matrix channel below that point.

The pattern of teeth is essentially a binary code, counting up from the left side of the main magazine. Code 0 (no teeth) is for space bars, which are not carried up to the distributor. Code 1 is skipped (no reason for this is given in the Linotype manual). Codes 2 through 92 are for the 91-channel main magazine, and the codes above that are for the auxiliary magazine, if one is installed on the machine. The widest auxiliary magazine has 34 channels, so its rightmost channel is code 125. Code 126 is unused.

Pi matrices

In typesetting, it is sometimes necessary to use characters which are uncommon or obscure enough that it does not make sense to assign them to a magazine channel. These characters are referred to as pi characters or sorts (no connection with the Greek letter π). Footnote marks, rarely used fractions, and mathematical symbols are examples of pi characters. In the Linotype machine, a pi matrix has all teeth present (code 127, no teeth cut away) so it will not drop from the distributor bar and will not be released into either the main or the auxiliary magazine. Instead, it travels all the way to the end and into the flexible metal tube called the pi chute and is then lined up in the sorts stacker. From the sorts stacker, the machine operator can (manually) pick pi matrices and insert them into the line being assembled as needed.

Paper tape operation

Some Linotype machines included a paper tape reader; for example, the machine at the Deutsches Museum shown in the photograph at the top of this article has that option. This allowed the text to be typeset to be supplied over a telegraph line (TeleTypeSetter). It also allowed for several tape perforator operators to prepare paper tape to be processed by a single Linotype machine, essentially decoupling the typing speed of the operators from the operating speed of the Linotype machine.

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