SIGNALING AND TELEGRAPHING, MILITARY. The term military signaling usually refers to the art of transmitting intelligence by visual signals. while telegraphing applies to the communication of messages by the electric cur rent, and in its application to military operations is considered here.
From the beginning of human existence signals such as signs, sounds, gestures, and other indica tions were used by the individuals of tribe or communities to communicate with each other. Sounds came first. These were followed by pictures of natural objects, the hieroglyphics of the ancients, and the other pictw•e writings of savage peoples. The accompanying illustration is a picture dispatch sent by North American Indians to the French during the war with Eng land in Canada. Translated it means that "they (the warriors) departed from Montreal" (repre sented by a bird just taking wing from the top of a mountain). The moon and the buck show the time to have been on the first quarter of the buck-moon,, answering to July.
While oral language was being developed. a means of communication beyond the limits of the voice was also undertaken by pantomimic signs; with the hands and body for short distances, by signal fires, smoke, a prearranged display of shields, spears, flags, clothing, and the like for longer distances. At an early date the necessity for a systematic code of military signals became apparent, and it is surprising to note the perfec tion attained by the ancients in the development of the theory and use of signals in time of war. The first record of a signal corps is given in the writings of Polybius about B.C. 200. The invention of the system then used is ascribed to Cleoxenes or Democritus, but the development of their ideas into a system was due to Polybius. As the principles of his plan underlie the mod ern systems of visual and telegraphic signals, the apparatus and method of using are given in some detail below. In the words of Polybius his system is described as follows: "Take the alphabet and divide it into five parts with five letters in each. In the last part, indeed, a letter will be wanting. but this is of no importance. Then let those who are to give and receive the signals write upon five tablets the five portions of the letters in their proper order and concert together the following plan: That he, on one side, who is to make the signal, shall first raise two lighted torches and hold them erect until they are answered by torches from the other side. This only serves to show that they are on both sides ready and prepared. That afterwards he again who gives the signal shall raise first some torches upon the left hand, in order to make known to those upon the other side which of the tablets is to be inspected—if the first, for example, a single torch; if the sec ond, two: and so of the rest. That then he shall
raise other torches also upon the right, to mark in the same manner to those who receive the signal, which of the letters upon the tablet is to be observed and written. When they have thus regulated their plan and taken their re spective posts it will be necessary, first, to have a dioptical instrument formed with two holes or tubes—one for discovering the right, and the other the left hand of the person who is to raise the torches on the opposite side. The tablets must be placed erect and in their proper order near the instrument; and upon the right and left there should be also a solid fence of about 10 feet in length and of the height of a man, that the torches, being raised along the top of those ramparts, may give a more certain light, and when they are dropped again that they may also be concealed behind them." Signals are either tronsicnt or permanent: transient When each element disappears upon completion; permanent when the signal is the combination of certain arbitrary elementary indi cations, e.g. sounds, colors, forms, etc., in ac cordance with fixed rules, known both to the sender and receiver. The elementary indications are called prinwry signals. The signs formed by uniting the primary elements are ealled combina tion signals. A combination may consist entirely of a single primary signal several times repeated the number of repetitions conveying the mean ing, e.g. 111; o• the combination may be formed by wilting several different primary signals, each used one or more times, e.g. 12:3, or 113, etc.
A class of signals is the term used to desig nate the number of elements used to make the signals, e.g. 131, 333, are signals of the third class; 12, 21 are signals of the second class, etc.; a code of signals is any number of pre arranged signals, each of which has a definite meaning to sender and receiver. If each letter is homographic the class term is indicated by a certain and always the same number of sym bols; clironoscinic or time signals depend for their meanings upon the interval of time be tween successive signals. For instance. a second of time between two signals might represent 'I,' and an interval of two seconds between the same signals `2,' etc.
The definition and examples cited above are il lustrated by the "United States Army and Navy Code Card" below. It is ealled the Myer system, after Brevet Brigadier-General Albert J. Myer, a former chief signal officer of the States army. It is a code of signals of two primary elements (1 and 2), the combination being of the first, second, third, or fourth class.