Code flags, which are largely used between ships, have not been
entirely displaced by the wireless. The usual naval code set consists
of a set of alphabet flags and pennants, ten numeral flags, and
additional special flags. This of course provides for spelling out any
conceivable message by simply hoisting letter after letter. So slow
a method is seldom used, however. Various combinations of letters and
figures are used to indicate set terms or sentences set forth in the
code-book. Thus the flags representing A and E, hoisted together, may
be found on reference to the code-book to mean, "Weigh anchor." Each
navy has its own secret code, which is carefully guarded lest it be
discovered by a possible enemy. Naval code-books are bound with metal
covers so that they may be thrown overboard in case a ship is forced
to surrender.

The international code is used by ships of all nations. It is the
universal language of the sea, and by it sailors of different tongues
may communicate through this common medium. Any message may be
conveyed by a very few of the flags in combination.

The wig-wag system, a favorite and familiar method of communication
with every Boy Scout troop, is in use by both army and navy. The
various letters of the alphabet are indicated by the positions in
which the signaler holds his arms. Keeping the arms always forty-five
degrees apart, it is possible to read the signals at a considerable
distance. Navy signalers have become very efficient with this form of
communication, attaining a speed of over fifteen words a minute.

A semaphore is frequently substituted for the wig-wag flags both on
land and on sea. Navy semaphores on big war-ships consist of arms ten
or twelve feet long mounted at the masthead. The semaphore as a means