now moistened with soldering fluid and covered with a
layer of tin-foil, which acts as a solder between the copper and the
later backing of lead.

The shells are now placed face downward in a shallow pan, and melted
lead is poured upon them until of a sufficient depth; then the whole
mass is cooled off, and the solid lead plate with copper face is
removed from the pan and carried to the finishing room, where it is
planed down to a standard thickness of about one-seventh of an inch.
The various pages in the cast are sawed apart, the guard-lines
removed, side and foot edges bevelled, head edge trimmed square, and
the open or blank parts of the plate lowered by a routing machine to a
sufficient depth to prevent their showing later on the printed sheet.

Then a proof taken from the plates is carefully examined for
imperfections, and the plates are corrected or repaired accordingly,
and are now ready for the press.

Although, owing to the expense and to the fact that the plate is more
or less weakened thereby, it is desirable to avoid as much as possible
making alterations in the plates, they can be made, and the following
is the course generally pursued. If the change involves but a letter
or two, the letters in the plate are cut out and new type letters are
inserted; but if the alteration involves a whole word or more, it is
inadvisable to insert the lead type, owing to its being softer and
less durable than the copper-faced plate, and it will therefore soon
show more wear than the rest of the page; and so it is customary to
reset and electrotype so much of the page as is necessary to
incorporate the proposed alteration, and then to substitute this part
of the page for the part to be altered, by cutting out the old and
soldering in the new piece, which must of course exactly correspond in
size.

As a patched plate is apt at any time to go to pieces on the press,
and may destroy other plates around it, or may even damage the press
itself, it is generally considered best to cast a new plate from the
patched one. This does not, however, apply to plates in which only
single letters or words have been inserted, but to those which have
been cut apart their whole width for the insertion of one or more
lines.

The plates having been finally approved, they are made up in groups
(or "signatures") of sixteen, and packed in strong boxes for future
storage. Each box generally contains three of these groups, or
forty-eight plate