s, and when
the ribbon is transferred to the casting machine these space
perforations so govern the casting that the line of type delivered at
the "galley" complete shall be of exactly the proper length, and the
spaces between the words be equal to the infinitesimal fraction of an
inch.

The casting machine is an ingenious mechanism of many complicated parts.
In a word, the melted metal (a composition of zinc and lead) is forced
into a mold of the letter to be cast. Two hundred and twenty-five of
these moulds are collected in a steel frame about three inches square,
and cool water is kept circulating about them, so that almost
immediately after the molten metal is injected into the lines and dots
of the letter cut in the mould it hardens and drops into its slot, a
perfect piece of type.

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