All this is accomplished at a rate of four or five thousand "ems" per hour of the size of type used on this page. The letter M is the unit of measurement when the amount of any piece of composition is to be estimated, and is written "em."
If this page were set by hand (taking a compositor of more than average speed as a basis for figuring), at least one hour of steady work would be required, but this page set by the Lanston machine (the operator being of the same grade as the hand compositor) would require hardly more than fifteen minutes from the time the manuscript was put into the operator's hands to the delivery complete of the newly cast type in galleys ready to be made up into pages, if the process were carried on continuously.
This marvellous machine is capable of setting almost any size of type, from the minute "agate" to and including "pica," a letter more than one-eighth of an inch high, and a line of almost any desired width, the change from one size to any other requiring but a few minutes. The Lanston machine sets up tables of figures, poetry, and all those difficult pieces of composition that so try the patience of the hand compositor.
It is called the monotype because it casts and sets up the type piece by piece.
Another machine, invented by Mergenthaler, practically sets up the moulds, by a sort of typewriter arrangement, for a line at a time, and then a casting is taken of a whole line at once. This machine is used much in newspaper offices, where the cleverness of the compositor has to be depended upon and there is little or no time for corrections. Several other machines set the regular type that is made in type foundries, the type being placed in long channels, all of the same sort, in the same grooves, and slipped or set in its proper place by the machine operated by a man at the keyboard. These machines require a separate mechanism that distributes each type in its proper place after use, or else a separate compositor must be employed to do this by hand. The machines that set foundry type, moreover, require a great stock of it, just as many hundred pounds of expensive type are needed for hand composition.
[Illustration: WHERE THE "BRAINS" ARE LOCATED The perforations in the paper ribbon (shown in the upper left-hand part of the picture) govern the action of the machine so that the proper characters are cast in the proper order, and also the spaces between the words.]