Signals
the means by which communications are made to greater distances than can be reached by the human voice.
To the eye these are conveyed by flags, lights, etc., and to the ear by guns, steamwhistles, fog-horns, etc. The most complete systems of signaling are those devised to enable ships some distance apart to communicate with each other. Of these the most important ones in the United States navy are the international code, the secret naval code, the wig-wag system, the Ardois night signal code, and a system of wireless telegraphy invented by officers of the navy. The The wig-wag system is the simplest of all, and in most general use when vessels of a fleet are lying in close proximity to each other. It is carried on by means of a small flag of conspicuous color, mounted on a staff some six or seven feet long. This is held by the person sending the message and is waved down, or to the right or left, in accordance with an understood arrangement. The international code, which is used by all vessels at sea, consists of 27 flags, of which there are 19 square ones, 6 pennants and 2 burgees. These flags represent letters, and in order to spell out a message combinations of three or four, having the same meaning in all languages, are hoisted to the top of the signal mast.