JOHN ALEXANDER JAMESON, JR. 1903-1934 .NGINEERING LIBRARY THIS BOOK belonged to John Alexander Jameson, Jr., A.B., Wil- liams, 1925; B.S., Massachusetts Institute of Technology, 1928; M.S., California, 1933. He was a member of Phi Beta Kappa, Tau Beta Pi, the American Society of Civil Engineers, and the Sigma Phi Fraternity. His untimely death cut short a promising career. He was engaged, as Research Assistant in Mechanical Engineering, upon the design and construction of the U. S. Tidal Model Labora- tory of the University of California. His genial nature and unostentatious effectiveness were founded on integrity, loyalty, and devotion. These qualities, recognized by everyone, make his life a continuing beneficence. Memory of him will not fail among those who knew him. <6 GILBERT SIGNAL ENGINEERING Complete and thorough instructions in all forms of Signaling FOR BOYS BY LEE CONOVER Formerly with Signal Corps U. S. Navy Prepared under the Direction of A. C. GILBERT Yale University, 1909 THE A. C. GILBERT COMPANY NEW HAVEN, CONN. New York Chicago San Francisco Toronto London COPYRIGHT 1920 BY A. C. GILBERT NEW HAVEN, CONN. ENGINEERING LIBRARY >/2^ TABLE OF CONTENTS CHAPTER I. HISTORY OF SIGNALING 7 II. GENERAL SERVICE CODE AND ITS USES ... 14 Wigwag system The flag, limitations and backgrounds The torch and lantern wigwag Wigwagging by searchlight. III. GENERAL INFORMATION AND ADVICE TO SIGNALISTS . 27 The message Duties of a signal unit Interruption of mes- sages Intervals Code time. IV. SEMAPHORE SYSTEM . . <> . . . 36 The semaphore machine Two-arm semaphore by hand flags. V. SOUND AND FLASH LIGHT SYSTEMS .... 46 Sound signals by bugle Signaling by pocket whistle Flash- ing or occulting light system The blinker The acety- lene lantern Searchlight signaling The heliograph The Ardois system The Very system. VI. TELEGRAPHY, RADIO-TELEGRAPHY AND TELEPHONY . 59 Telegraphy The American Morse Code Receiving telegra- phy Radio-telegraphy Telephony The telephone for sig- nal purposes. VII. THE SIGNAL TOWER 68 Suggestions for erecting a signal tower Secret codes and ciphers The cipher disc How to make a cipher outfit. VIII. MARITIME SIGNALING 77 Flags and correct way of using Flags of the International Code and how used Method of signaling when no other ships are in sight Distant signals International flag waving system. IX. U. S. NAVY FLAG SIGNALS 85 How navy signals are executed Calls U. S. naval flag etiquette Time for flying colors Personal flags Yacht flags. X. MISCELLANEOUS SIGNALS 95 International life saving signals Signals for a pilot Inter- national distress signals, for day International distress signals, for night. XI. How TO MAKE SIGNAL APPARATUS 99 How to make a field buzzer How to make a heliograph How to make a semaphore and blinker. 88971 8 FOREWORD To do big things, just as men do who are experts in a certain kind of endeavor, I believe is the greatest wish of every boy. I know when I was a boy it was very interesting to me to find out all I could about electricity, chemistry and other practical subjects because they held my attention. There was all kinds of fun in this for me. Whenever I got working on my experiments I had the greatest amount of pleasure. Let me tell you, too, I was a happy boy when I had completed my work and could show it to others. I remember how I used to watch army men at signal practice. It was mighty fascinating to see them at the camp with their apparatus and to observe the methods they used to send messages. It looked hard, but when I thought it over it seemed very easy. Signaling will prove just as interesting to you as it did to me, and because I think it means a great amount of fun for you, I have had this book prepared by a man who was an expert in sig- nals and who did very fine work in the Navy as a member of the Signal Corps. Every detail is explained with the greatest care. The facts are authentic and you can depend on this book to give you a thorough knowledge of signaling. You can learn about signals from the very beginning when firebrands were used in a primi- tive fashion many years ago to the present time when messages are flashed and sent by the most modern inventions. SIGNAL ENGINEERING ',__ s j o '4IG U 3 1, Competing teams of the oU> S. Army e ji$l ^N^ on ^the xoof of the Grand Central Palace, New York City, during a recent dg^a!/ cQrrt,est** * J* 9 Chapter I In Webster's Dictionary we find that the meaning for signal is a sign and in looking up sign find its definition to be signal- ing hence they are certainly very closely related. At any rate a signalman is one who puts signs into action and that is what we are going to do, By a little perseverance you will master (7) 8 GILBERT BOY ENGINEERING each lesson step by step and in a very short time, with the ease of a master signalman, be able to flash a message through space for a distance of twenty miles or more. The early American Indians wrote their picturegraph mes- sages on the bark of trees, their canvas wigwams and other conspicuous places. The totem pole of the Northwest and Alaskan Indians is a good example of symbol writ- ing. In later years the more advanced tribes de- vised crude codes by which they sent messages by means of smoke. Many hundreds of years ago the ancient tribes in Europe put into practice the habit of carv- ing picturegraph stories on rocks. Like the Ameri- can Indians, they later found methods of sending their messages through Space with the aid of a , cumbersome code and lighted torches. It seems that the earli- est forms of optical teleg- raphy, as visual signaling is sometimes called, in- volved the use of fire- brands or torches. Of Boy Scouts in mountain of N. Y. State sis- COUrSC these COUld Only a tree '~ be used at ni sht, and his - GILBERT SIGNAL ENGINEERING Boys practicing signals at a Scout Camp. Courtesy of Boy Scouts of America Boy Scouts^ of Scouts of America FIG. 4 Denver, Colo., Troop practicing semaphore. Courtesy of Boy 10 GILBERT BOY ENGINEERING tory gives us no reliable records of any day signals until the earlier forms of semaphore hundreds of years later. About 200 B. C. a method of signaling was employed by the Greeks, in which torches were used. A system of measuring the flashes or exposures so as to make a simple code was invented. The Romans also used torches for signaling, and during the early Greek and Roman Wars probably the first step was taken in Signal Corps organization. These warrior signalmen were known as "fire shakers," and to obtain points of vantage they built in many places throughout Europe signal stations, some of which are still standing to this day. Mention is made in the Old Testament of lighting signal fires for the purpose of conveying intelligence. It seems that the method of using signal fires and torches was very popular among the early signalmen. The fact remains that even as late as the Civil War in America torches were still in use by the Signal Corps of the Blue and Gray Armies and are rivaled today only by the more modern devices in which lanterns and electric lights are used. |In the year 1623 the Marquis of Worcester (England), in- vented a plan of letters for signaling by day and night. Monsieur Amontons (France 1663) recommended the holding up of large letters of the alphabet to be viewed by telescope. Robert Hook of England was the first to really develop the modern idea of visual signaling. He used various shaped ob- jects, suspended on a frame, to indicate letters of the alphabet. Claude Chappe, a young French engineer, in 1790 invented a system of semaphore, and other Frenchmen followed him with the more advanced forms of indicators with semaphoric wings. During the reign of Queen Elizabeth, the Duke of York (later James II) introduced a system of methodized signals from which later sprang the first British Naval Code. GILBERT SIGNAL ENGINEERING 11 FIG. 5 Signalmen of the U. S. Navy on signal bridge of the U. S. "Wyoming" 12 GILBERT BOY ENGINEERING In 1816 Sir Home Popham of the British Navy gave the world a new system of semaphore telegraph, which was adopted by the British Admiralty. William Penn of America is also given credit for being among the first (if not the first) to get together a code and system for communication at sea. In reviewing the history of signaling it might be of interest to know that the first telescope was invented about the year 1600. This important invention increased the range of the naked eye to a very great extent and made signaling an im- portant method of communication. The needs for signaling, we can see, were first wanted by armies so as to bring about rapid exchange of thoughts. It proved faster and more reliable than messengers, who were always subject to delays or liable to capture. Still, today, its paramount use is found in the armies and navies of the world, where the Signal Corps is without a doubt the most important branch. In November, 1863, during the Civil War in America, when General Grant took command of the Union Army before Chat- tanooga he established his .Signal Corps on a big mountain and was able to keep in touch with his forces during many of the great battles, one of which was the famous "Battle Above the Clouds/' fought on Lookout Mountain. Today this moun- tain, from which his Signal Corps operated, is called Signal Mountain and will stand as an everlasting monument to the Signal Corps. If it is ever your good luck to visit this beautiful spot in Tennessee you will then realize to what extent accurate signals were and can be exchanged. During the late war the Allied armies used many ingenious methods of signaling, including the improved blinker systems, sound systems and radio. One of the newest schemes is that of sending a message from the ground to aeroplanes by means of GILBERT SIGNAL ENGINEERING 13 "Panels." This is done with a code and panels of colored cloth laid on the ground. The importance of Signal Corps work can be realized better when it is known that the Signal Corps of the U. S. Army alone, during the time it took part in the war, used 126,000 miles of wire for intelligence communications by telephone and telegraph lines. (Liaison work.) More scientific knowledge of our neighboring planets will undoubtedly be accomplished by means of high powered signal apparatus. The matter of an exchange of messages with the inhabitants (if any) of these planets is receiving serious thought by many scientists. Several years ago a plan was advanced to do this by means of the heliograph method. This scheme was to use great mirrors with a huge shutter arrangement so as to send the messages by means of great flashes. Who can tell but what you may be able to invent the apparatus to send a mes- sage that far? It would, of course, take years to develop, but some one will eventually find a way to complete this wonder system in signaling. Chapter II GENERAL SERVICE CODE AND ITS USES A code of signals is a collection of symbols agreed upon. The International Morse or Continental Code is the most widely used of all modern codes due to its easy adaptability to so many forms of signaling. The International Morse Code was first used for transmitting messages by ocean cables and later adopted by the armies and navies of the United States and Great Britian. By the official recognition of the Army and Navy, the Boy Scouts and other organizations it has come to be known as the "General Service Code." From this point on in the book it will be called by that term. The General Service Code is a code of dots and dashes com- prising the twenty-six letters of the alphabet and the numerals, with additional symbols. The following signal systems are based on this code: 1. Sound system. 2. Heliograph system. 3. The Ardois system. 4. Flashing or occulting light system. 5. Very's night system. 6. The Wigwag system. 7. Radio. 8. Buzzer and Field Telegraph. The U. S. Army, commercial telegraph lines and short cables at the present time use the American Morse which has slightly different symbols. (14) GILBERT SIGNAL ENGINEERING 15 Alphabet -GENERAL SERVICE CODE A B C D E S0* raao F G H I J K L M N P Q . R S T U Mi V V X Y Z NUMERALS 1 . ii 6 2 . > aaoiB a 7 __ 3 , ^4^ an flan 8 * 4 , 8KB 9 > & ~ CHART 16 GILBERT BOY ENGINEERING In using the General Service Code with some of the systerm just mentioned, it is necessary at times to make some minor changes in the arrangement of sending numerals and conven- tional signals, but the principle of the code always remains the same. The changes will be explained from time to time as yoi become familiar with the systems. You can readily see the importance of knowing this code be fore any advance can be made in signaling; so now turn tc Chart 1 where you will find the General Service Code alphabel and numerals written. First study the alphabet. A good plan that will help you tc memorize it will be to write over and over again the characters on paper, after which you can get another boy to test youi memory by having him call out at random letters of the alphabe to you. You can reply in dots and dashes. Another way is t construct short sentences and then rewrite them under the do and dash characters. For example; N MUST KNOW E The numerals of the code are much easier to learn than the alphabet. You will note that they are written by using a com- bination of five dots and dashes for each number. Remember numbers are always represented by five dots, dashes, or a combination of both. Number one is made with one dot fol- lowed by four dashes, .1 ; number two by adding L 1 GILBERT SIGNAL ENGINEERING 17 Condetilioml Oittafe, etc PUNCTUATION Period, ' ** Comm& Setnicolott ** > ^^GoLoti . ApOStVOphe *mmmm*m*m* Of Quotation Hg&Zi (fagiatdtg and, en&tig)*** ++m** to itutic&te & r & Z5# Zefovg &tul gffep -zHovds to uzulev2in&} ********* Doii&le Dct&h (to Ze used &etteett pre&ttiile 3fa2&&3 * Oell)CZl &&tz?$3 cZZZsL &Qcy Op ttZgfSiS^G * body stv e f and iozatediaiely &epove cpaciiott) mm # mm SECONDARY MEANINGS mmmm (II) Mfgaiifo Of No mm. CM) (L) Preparatory (R) (P) Affivttt&tiJie of Yes CHART 2 L 2 18 GILBERT BOY ENGINEERING TOR USE WITH O5X5. T &te DA day WRD U you. CK cfesctf NSC zttess&ie "* <& B te FM from AHR R stv TH Ihroigh CXK W sf/k GA ^ ^a^2f GN TT ?ft5f GM ^W *W, NITE UR j^zzr OB official CN ct OF/1 official BF before SIQ sigtt&tuve BN 2^^a ANS &*>5i&f HR &e^ MR HV &2& ML /w^ ^. mile AF *&^ MU OK ^// right ^ is &?so cozmttotzZy vised receipt *f CHART Z CONT'D, GILBERT SIGNAL ENGINEERING 19 another dot and dropping one dash, .. This same plan is followed until you reach number six, when you start with one dash followed by four dots .... For number seven write two dashes and drop one of the dots, . . ., and so on down the line to zero which is expressed by five dashes Chart 2 gives the punctuation marks of the code, secondary meanings of several letters of code alphabet, conventional sig- nals and abbreviations, most of which were taken originally from the American Morse Code but are adaptable to all methods of signaling and are used by every practical signalist. In using abbreviations, no matter what the system, always remember they are sent as a complete word. THE WIGWAG SYSTEM Now that you know the General Service Code, you are ready to make use of this knowledge by practicing short messages with the Wigwag System. In the Army, for practicing the wigwag, a stick of light wood about 18 inches long is used, and is called the wand. The wand is held loosely between the thumb and forefinger and waved rapidly to right or left to indicate letters of the code. A wand can be made easily from the small end of a bamboo pole or any light wood. By referring to Chart 3 you will see illustrated a boy holding the single stick flag at position or ready. He is standing erect and facing squarely the receiving station which is represented on the chart. The flag is held vertically in line with center of head. This position with three motions constitutes the Wigwag System. On the chart at the left is shown the first motion, which represents the dot. To make this motion the flag is waved from position to right of sender and back to position. This mo- 20 GILBERT BOY ENGINEERING FIG. 6 ^Members of a U. S. Marine Signal Corps Company wigwagging from a signal tower erected on roof of a building at Vera Cruz, Mexico. Courtesy of U. S. Marine Corps tion is always made in a plane at right angles to the line con- necting the two sta- tions as shown in center of your chart. The second motion shown on right of chart gives you the dash and is made ex- actly as above only to left of sender. The third motion shown at bottom of the chart is made by a wave of the flag from position direct- ly in front of sender to your feet, and in- stantly returning to position or ready. This third motion represents front or in- terval. One front mo- tion is given at end of each word, two at end of a sentence and three upon comple- tion of a message. In making a letter of the alphabet say the letter Q four strokes are made ; i. e. LEFT LEFT RIGHT LEFT. It is not necessary to pause at position in going from extreme left to right or vice versa. However, a slight pause should be allowed GILBERT SIGNAL ENGINEERING 21 >'#!fp System POSITION REAOY . 3TA. OffE FRONT MOTION - HO TWO Ff*QNT MOTfONS NO OF SENTENCE. THR FRONT MOTIONS- ! * 'MOT/ON CHAPT 3 22 GILBERT BOY ENGINEERING at the completion of each letter. Then con- tinue to finish your word and to give the front sig- nal. A great deal of prac- tice is necessary to be- come a rapid sender by the single stick flag. Care should be taken not to foul the flag on the staff, as the full fly of your flag should always be seen by the receiving station. This is some- times hard to do, espe- cially on a windy day, but experience will teach you how it is best to avoid a troublesome sit- uation. The U. S. Army uses two standard outfits for wigwagging. These are known in the Signal Corps as kits. The two-foot kit contains a three- jointed hickory staff, jointed with brass screw ferrules, and when fitted together makes a strong pole 69 inches long. The flag is made fast to pole by means of three ties of tape. These are looped through brass eyes on pole. Two flags, the size of each being 2 feet square, are provided, one of bright red material with a white center 8 inches square and the other white with red center. The flags and pole can be packed in a canvas kit about 2 feet in length. The other outfit used is the "four-foot kit." In this outfit the FIG. 7 Boy Scouts sending a message by two-arm semaphore. Courtesy of Boy Scouts of America GILBERT SIGNAL ENGINEERING 23 pole is heavier and when jointed is 12 feet in length. The two flags are 3 feet 9 inches square with 12-inch centers; they are of alternating colors, red and white, as in the smaller outfit. THE FLAG, LIMITATIONS AND BACKGROUNDS The size of the wigwag flag to be used depends entirely on the distance you want to transmit a message, and whether or not the receiving station is equipped with glasses. Under ordi- nary conditions a flag of 18 inches or 2 feet can be read a dis- tance of one mile without glasses and two miles with glasses. This is the extreme limit for a flag of that size. Nearly all single stick flags are made up of a combination of red and white colors, as these colors usually give great- est contrast. Red and orange is also a good combination. Always select the color of your flag so as to give greatest possible contrast against the back- ground. The white flag should never be used where your back- ground is a snow- covered hill or light sky; but if sky is heavily clouded a white flag will prove best. The red flag should be used against a light background, of course. As some back- are very de- 1 FIG. 8 Boy Scouts of Ansonia, Conn., sending a long distance wigwag message at sundown. Courtesy of Boy Scouts of America 24 GILBERT BOY ENGINEERING ceiving at times, it will take a little study on your part to deter- mine the proper flag to use for particular conditions. THE TORCH AND LANTERN WIGWAG At night the signal flag is of no use; the substitute is either the torch or lantern. If you are out in the woods and want to send a message at night to an adjoining camp and have no torch or lantern at hand it is great fun to use firebrands. Se- lected sticks of dry wood can be placed in the camp fire and lallowed to burn a minute or two. The signalist can then send a message to his comrades. It will sur- prise you to learn the distance you can send messages by this method. Care should be taken to get out of range of your camp fire, as its reflection would hin- der the receiving par- ty. Signaling at night A U. S. Marine semaphoring, Haiti, West Indies. IS always subject to Courtesy of U. S. Marine Corps GILBERT SIGNAL ENGINEERING 25 FIG. 10 U. S. Army Signal Corps on Mexican Border more adverse conditions than by day. Therefore it is advisable to send messages much slower at night. Where the distance is great, an additional light should be placed in line with center of your body and about 2 feet from the ground to act as an indicator or point of reference in the motion. About the most practical way of wigwagging at night is to. use two lanterns, one for the indicator and the other for trans- mitting. Care should be given at night to the front motion, so as to make it distinct. This motion can be simplified somewhat by moving the lantern vertically from your head to your indi- cator light. For long distances you can fasten a lantern to a pole. 26 GILBERT BOY ENGINEERING A good torch can be made by nailing an old tin can to a pole about 6 feet long; stuff the can with old rags or waste; pour over these a little oil and light with a match. This will give you a torch that will burn long enough to send any message of reasonable length. WIGWAGGING BY SEARCHLIGHT The beam of a searchlight may be used for wigwagging at night and in the U. S. Navy it is very frequently used. The rays of the light are directed vertically and swing from right to left to indicate the dots and dashes of the General Service Code. All motions are the same as in the single flag Wigwag System. Chapter HI GENERAL INFORMATION AND ADVICE TO SIGNALISTS Now that you have become familiar with the General Service Code and one method of sending it, a few rules can be given that will be of help in all systems of signaling. Many bits of this advice may sound military, but you may well take heed of it for it is essential to practical signaling more so if you are a Boy Scout or some day have occasion to work with a military organization. Signaling, like all professions, has its established terms and a correct plan of procedure. To gain a full knowledge of sig- naling it is necessary that you become accustomed to handling a message correctly. A Signal Station consists of one or more signalmen operating as a unit and ready at all times to send or receive a message. The station can be either temporary or stationary. The Home Station is station to which you are assigned. The Sending Station is station sending message. The Receiving Station is station receiving message. To Call a station, it is the usual plan first to attract attention. This is done in the various signal systems as follows : 1. Wigwag system: Succession of dots and dashes. 2. Semaphore system : Waving flags at attention. 3. Sound system: Succession of dots (or toots). 4. Heliograph system : Long and short flashes. 5. Ardois system : Display of four white lights. 6. Radio system: . . 7. Buzzer system : Station call letter. (27) 28 GILBERT BOY ENGINEERING 8. Telegraph system : Station call letter. 9. Flash light system : Short flashes or dots. In addition to attracting attention, if the call letter or letters of the station you desire to communicate with are known, the signal representing them should be made at intervals. It is very important that each signal station has a call of one or two letters. Any letters can be adopted such as X or XY. This is essential for the reason that you may be facing and within signal distance of two or three stations at times and want to send only to one of these, individually. Note: If call letter is un- known, use the letter A. The Receiving Station always acknowledges your call by making R and its call letter. After this acknowledgement you are ready to proceed with the message. THE MESSAGE The plan of the message varies at times, according to the organization ; however, all messages are divided in a general way as follows: 1. Preamble. 2. Address to. 3. Text of message or body. 4. Address from or signature. The preamble of the message is reserved solely for use of signalmen dealing with the message. The preamble or intro- duction of a message consists of the serial number of message and time message is handed in at station and accepted for trans- mission. All stations use serial numbers in handling messages, begin- ning with number one and so on up for each twenty-four hours, after which a new series is started. Next comes the call letter of sending station or office of origin, the signalist's personal signature (all signalmen must use a personal signature as, J. J. GILBERT SIGNAL ENGINEERING 29 for John Jones, etc.) the check of message (number of words in body of message), and the class of message. To arrive at the exact number of words in the body of a mes- sage this rule is followed: Include in count the address after TO and all words in body, including the address following FROM, but do not count FROM or SIG. if that term is used by signalists. Abbreviations, figures and names of cities and states should be counted as one word, for example : C X K (get reply) is one word ; South Chicago, Illinois, or So. Chi. 111., is counted as two words ; and one-quarter as one word. The message usually indicates whether it is official business (OB) or official message (OFM) as collect, or paid message, urgent, etc. The Address of a message should always contain enough words or information to insure its delivery. The Address FROM should convey the same amount of intelli- gence. The Double dash ... of the General Service Code is always used between the preamble and address TO; between the address and text; and between text and from or signature. The following is a message handed in at a signal station at Brown's farm (call letter B) at 10 A. M. to be transmitted to station X Y (Smith's Crossing). Signalist John Jones (J. J.) takes the message : (To) Bill Smith, Smith's Crossing. Get your gang together and meet me at the Stony Creek Bridge at 2 P. M., I will bring the bunch, don't forget your skates, ice is one-quarter foot thick. (From) Harry Brown, Brown's Farm Get reply to this message. (C X K) 30 GILBERT BOY ENGINEERING After Jones checks the message he finds it contains 38 "signal words." He numbers it 8 (as it is the eighth message he has sent that day from his station) and decides to send it by single flag wigwag. After getting attention of station X Y he pro- ceeds to send as follows : 8 ( ..) interval or front TEN front A. M, front, B [(Brown's Sta. call) front, C.K. 38 (message check) front, JJ. (Jones' signature) front, OF (official message) front ( . . . ) (double dash) TO : front Bill Smith Smiths Cross- ing get ur gang together and meet me at t Stony Creek bridge at 2 (. . ) P.M. I will bring t bunch don't forget ur skates ice is ( . . . ) (double dash used before fraction) 1 (. ) ( .. .) (indicating fraction bar) 4 ( ) foot thick (_..._) (double dash) - SIG. Harry Brown Browns Farm C X K (get reply) (. . .) (cross) or (. . . . ) (mean- ing end of work). Station XY acknowledges receipt of message by O.K. or . . (R). The receiving station has a record of this message as sent above and the transaction is complete. Of course, if you are not an expert signalman, to lessen liability of errors, it is best to spell out all numerals, fractions and abbreviations. A message handed in at a signal station should always be looked over, for an omission of one word may change the meaning of the whole message. The advantage and importance of checking by sender and in the recheck by the receiving sta- tion can be seen at once. Both sending and receiving stations should record on the message what system was used in handling it. The date should also show, although the serial numbers, in a measure, indicate GILBERT SIGNAL ENGINEERING 31 the dates. As you will recall, they are changed every twenty- four hours. In military organizations all messages are considered strictly confidential. DUTIES OF A SIGNAL UNIT You have been told that a signal station consists of one or more signalmen operating as a unit. Where there is more than one, each must have his duties to perform; therefore, it is ad- visable where three boys are operating a sending station to know just what each boy's duty is. First Boy or Caller takes charge of the messages, checks same and makes proper entries. When message is ready to send he calls the word or group to Second Boy or Sender whose duty it is to send the message as called. His other duty is to see that his sending equipment is always in good condition. Third Boy or Answer Reader reports signal as being answered and watches for interruptions from receiving station, using bi- noculars when necessary. Note : Should four boys be operating a station, the fourth boy will act as a messenger. INTERRUPTION OF MESSAGES At times signal units have a good many messages on hand to dispose of and have these messages in course of transmission when a very important urgent signal is handed in. It then be- comes necessary to make the Break Signal, which is the atten- tion sign by all systems. As soon as the break is acknowledged, proceed with the more important message. The Answer Reader should always be on the lookout for 32 GILBERT BOY ENGINEERING signs of error from receiving station and report to sender what portion of message has been missed. The duties of these boys at a receiving station are similar. First Boy, Reader (with binoculars), reads each letter, sign or numeral, calling out group on ending of each word, etc. Second Boy, Answerman, stands by to make any necessary in- terruptions and to answer signal as required. Third Boy, Writer, writes on signal form each group or signs as called out by the reader. The first boy must be an expert on signals, for it is his duty to take charge of the signal unit. When his station is acting as a receiving station, it is his business to read correctly all messages. He should enforce a certain amount of discipline around the sta- tion, and not allow any unnecessary talking, etc., while signalmen are operating, INTERVALS The intervals of the General Service Code were purposely omitted in Chart 2 so as not to confuse you with their secondary meanings. They are as follows : Interval Double Interval Triple Interval (same as period) (same as cross) Intervals are expressed as follows in the various systems: Interval Double Interval Triple Interval 1. Wigwag front motion (twice) (three times) 2. Semaphore flags crossed or 2 chop-chop 3 chop-chop machine closed signals signals GILBERT SIGNAL ENGINEERING 33 Interval Double Interval Triple Interval 3. Sound (Bell) ... (short taps) (Whistle) long blast . . . 4. Radio Flashing light Heliograph (space) Buzzer and Telegraph 5. Ardois . . (twice) {three times) CODE TIME You have been informed that, when a message is handed in at station and accepted for transmission, a record of the time is made and sent in the preamble. This code time serves to show how long a message has taken to pass through the hands of the signalmen. In order to save time to spell out or to send code time by numbers, the Letter Clock System is sometimes used. Chart 4 gives you the letter clock, which is an ordinary clock- face with letters placed against the hours. The twelve hours are denoted by the first twelve letters of the alphabet, omitting the letter J. These letters stand not only for the hours but also for periods of five minutes; for example: A would be one o'clock and five minutes past any hour, B two o'clock and ten minutes past any hour, and so on. AA would mean one five, AB would mean one ten. To denote intermediate minutes the letters RSWX are used in every period of five minutes. Thus MR means one minute past twelve ; MS means twelve two. The hands of clock shown on your chart show time to be four minutes past six o'clock and the letters that denote that time L 3 34 GILBERT BOY ENGINEERING LETTER CLOCK CHART GILBERT SIGNAL ENGINEERING 35 are FMX, reading in code time 6.04 either A. M. or P. M. as case may be. Should a message be handed in at a station at exactly noon or midnight it would have to be recorded by code at one min- ute past to avoid confusion. The message handed in at noon would be put in code as MR P, M. and at midnight MR A. M. Chapter IV SEMAPHORE SYSTEM The word semaphore is derived from the Greek word seema, meaning a sign, and phero, to bear or carry. This system is sometimes called brachial telegraph, meaning telegraphing with arms, THE SEMAPHORE MACHINE The two-arm semaphore machine is used in permanent sta- tions only, as it is not a portable piece of signal apparatus. The semaphore machine is authorized for use of the U. S. Army at fixed stations and is used on all the larger ships of the U. S. and other navies. This semaphore machine has two arms or vanes for forming the characters of the code and a third arm or indicator dis- played on right of sender (on left as viewed by receiver) as a point of reference to motion. Semaphore machines are usually about 8 feet high, with arms of 2y<2 or 3 feet. The arms are operated by two levers which are placed on the machine at average height of elbows of the body. An additional lever operates the indicator arm. The machine is painted black or gray, while arms and indi- cator are colored a light yellow. For night use the machine is fitted along entire length of the arms with electric lights. The indicator is used by day only to indicate direction of sending; at night, instead of the indicator, a red electric light is used at top of machine. This light is screened to rear, and if machine is facing receiving station squarely it will (36) GILBERT SIGNAL ENGINEERING 37 SEMAPHORE MACHJNE A 1 d CRROW a z 1 3 E 5 F 6 JT G 7 H 8 I 9 IX SteCUTf. FRC PARATOR V M N . /\FFiW*A T ACKNOWLEDGE u y CORNET U.S. NAVY LETTERS 1 ATTEMTJ6M 38 GILBERT BOY ENGINEERING not be seen. Semaphore machines are mounted on a pivot so as to turn in any direction. Chart 5 will show you alphabet of the semaphore code ex- pressed by a two-arm machine. In addition to the two-arm machine used by the U. S. Army and Navy there are several other types of machines, some having as many as six arms. The most common of these is the four- arm semaphore used for transmitting distant signals by the International Code and by fixed shore stations to communicate with ships of all nations. A great many of these semaphore stations are found on the coasts of Great Britain, France, Italy, Spain and Portugal. Of course you are familiar with the type of semaphore used by all up-to-date railroads, but do you know what these signals mean? A vertical position of arm means safe at night a white light is displayed. A horizontal position of arm means danger at night a red light is displayed. The intermediate position of the arm means caution at night a green light is shown. TWO-ARM SEMAPHORE BY HAND FLAGS The method of semaphoring by hand flags is used in both Army and Navy, Boy Scouts, Girl Scouts and nearly all organi- zations using signals. This system of signaling has been more highly developed in the U. S. Navy than in any other place on account of its rapidity and simplicity for the exchange of messages between ships of the fleet. In the Army and other military organizations this type of signaling is somewhat limited on account of short range. The usual range for hand flags of 18-inch size is about one mile with the naked eye, and is always dependent upon your background GILBERT SIGNAL ENGINEERING 39 TWO-ARM SEMAPHORE INTERVAL CORNET U.5.M, ATTENTION DOUBLE INTERVAL. IS TWO CHOP CHOP SIGNALS. TRIPLE INTERVAL is THREE CHOPCHOP SI6MALS CHOP CHOP U.S. ARMV U& ARMY- NAVY SIGNALS 40 GILBERT BOY ENGINEERING TWO-ARM: SEMAPHORE .A EKKOK 1 B H 8 I IX EXECUTE 9 CMAKT 6 GILBERT SIGNAL ENGINEERING 41 TWO-ARM SEMAPHORE K NEGATIVE H ANNULLING i H, ACKN0H/ CHART 42 GILBERT BOY ENGINEERING TWO-ARM 5EMAFHORE V CHART 6 GILBERT SIGNAL ENGINEERING 43 and the light. Much greater distance is possible, of course, with use of a telescope. The size of flags used by the Army are 18 inches square, di- vided diagonally into two parts one red, the other white. The field and coast artillery use the same size except as to colors, which are scarlet and orange. The arrangement is a 9-inch square in center of scarlet and a border of orange for work against dark background. For light backgrounds the order is reversed. The staffs used are 24 inches long. The U. S. Navy uses flags from 12 to 15 inches square of blue with white square center for light backgrounds. For dark backgrounds, a flag of red and yellow colors, arranged diag- onally is used. Now turn to Chart 6 and study the different positions. The boy is holding the flags so as to make the characters of the alphabet. You will notice that all positions by hand flags are the same as by machine, excepting the interval, which is made by crossing flags in front of sender's legs. The quickest way to learn semaphoring is to practice with one of your friends. After memorizing all the characters of the code, send simple words to each other and later short messages. In making the characters all motions, pausing slightly follow- ing each, should be sharp and distinct to avoid confusion. At the end of a word the interval shown on the chart and already described is used. At the end of a sentence the double interval, two chop-chop signals, is made. At the end of the mes- sage a triple interval, three chop-chop signals, is used. The chop-chop signals shown on your chart are made by placing both arms vertically to right of sender and by working flags up and down in a chopping motion. Additional symbols found in your chart are attention or cornet, numerals follow, signals follow and letters follow. 44 GILBERT BOY ENGINEERING This attention signal is, of course, used to get attention, and is made by agitating the letter R. The numerals follow signal is made by crossing flags over head and is used to designate the fact that you intend to use the numerals which are expressed by secondary meanings of your alphabet letters A to J as shown on chart. The numerals are made by semaphore in this way by all organizations except the Navy, where regulations require them to be spelled out in full. The interval must be used following each numeral. Signals follow is made by reversing the letter L and is used to designate the fact that a code message or secondary meanings follow. Letters follow is used only by U. S. Army and Navy and is made the reverse of the letter T. It signifies letters will be used to spell words. A great many of the conventional signals and abbreviations given in your General Service Code can be adopted for sema- phoring. To indicate an error in semaphore the letter A is used as in the General Service Code. As A already has a sec- ondary meaning (the numeral one) it is necessary to agitate your flags a little. The conventional interrogatory signal is made by agitating the letter O. In sending an official message by semaphore the same rules are followed as given in preceding chapter. No punctuation marks are given in the semaphore code and if used they must be spelled out. Do not slur your letters in semaphoring but make them exactly as shown on charts. However, now that you are be- coming a real signalman, it will not do you any harm to know that experts at semaphore signaling sometimes deviate from the regular motions. To explain this in a practical way, spell the following word without moving your right arm, after mak- GILBERT SIGNAL ENGINEERING 45 ing the first letter of word MANILA. Spell BED also with right or left arm only. In semaphore signaling when sender makes an "end of word" sign, the receiver acknowledges this, if the message is under- stood, by extending his arms horizontally and by waving them until the sender does the same and message is finished. By machine, the receiving station fixes his call letter station- ary until the message is received and understood and then the machine is closed. Chapter V SOUND AND FLASH LIGHT SYSTEMS SOUND SYSTEM. As early as the 17th century attempts were made to establish communications by artillery and mus- ketry firing. The system of sound signaling, came into use at this time. The sound system is based on the General Service Code and is used more commonly by the ships of the Merchant Marine and the U. S. Navy. However, due to its aptness to cause con- fusion, it is rarely used by ships except in cases of emergency, such as in fogs or when a breakdown of other signal apparatus occurs and only in regions unfrequented by other vessels. Messages are sent by the sound system by use of steam whistle, foghorn and bell. When the steam whistle is used, messages are spelled out, except in the case of the U. S. Navy, which uses the Navy Code. The intervals by all methods of the sound system are ex- pressed as previously given in Chapter 2, under intervals. You will notice a difference in signals for interval in case of the whistle or bell. In the case of the whistle one long blast represents the dash and a short one for dot ; but in use of the bell a continuous sound cannot be made, therefore it is necessary to use two strokes to make a dash and one stroke for a dot. SOUND SIGNALS BY BUGLE The Navy has lately adopted a code for signaling by bugle or trumpet; this code was invented by a high school student of West Roxbury, Mass. The code is given you in Chart 7. No (46) GILBERT SIGNAL ENGINEERING 47 U.S. NAVY BUGLE CODE DJ7J J FJJJ/ G JJ KJJ.T END OF MeasAOE ? oJJJJ R JJJ sJJ -rtt uj;jj J J OHAKT T 48 GILBERT BOY ENGINEERING special musical knowledge is necessary to sound the characters of the alphabet and numerals, except to acquire what is known by players of wind instruments as the "lip," which comes very easy with a little practice on a horn. You will notice the letters of code are expressed by not more than four notes and all numerals by five, either eighth or quarter notes. The relative value of the eighth note to the quarter note is one-half. Therefore an eighth note is made by a short blast on the horn and the quarter note by a blast twice as long. The eighth notes are the ones having the small pennant at tip of the stem. Signals can be sent by this method in any key, but it would be very confusing to change key or pitch of your tone in middle of message. Avoid slurring the notes and give special attention to length of blast signified by eighth and quarter notes. Intervals between words in Bugle Code are made by allowing a space, and the end of a message by one high note. To call a station by Bugle Code blow long blasts followed by station's call letter. If call letter is unknown, use the letter A which is common in all signal systems when a station call is not known. To acknowledge receipt of a message blow one long note. SIGNALING BY POCKET WHISTLE All boys are familiar with the police whistle or similar type carried by Boy Scouts. The cost of these whistles runs from 15 to 50 cents and every boy should possess one for signaling or emergency use in the woods. To signal a message by pocket whistle use the General Service Code. The special conventional signals by whistle used by the Boy Scouts are as follows: GILBERT SIGNAL ENGINEERING 49 1. One long blast means "Silence," "Attention/* "Look out for my next signal," also used in approaching a station. 2. Two short blasts mean "All right/' 3. A succession of short, sharp blasts means "Rally," "Come together," "Close in." 4. A succession of long, slow blasts means "Go out," "Get farther away" or "Advance," "Extend," "Scatter." 5. Three short blasts followed by one long one from scout master calls up the patrol leaders i. e., "Leaders come here." 6. Three long blasts means "Danger," "Look out." 7. A succession of alternating long and sharp blasts means "Mess Call." All whistle signals should be obeyed as quickly as possible, no matter what work you may be doing at the time. FLASHING OR OCCULTING LIGHT SYSTEM The equipment used to send messages by this system is the electric blinker, operating with a telegraph key, and the lantern or searchlight equipped with shutters. THE BLINKER The electric blinker is authorized for use in the U. S. Navy and is also used by many other navies and merchant vessels. The electric lamp is usually placed at the peak of the foremast or on yardarm and operated by a key from bridge of ship. Incan- descent lamps, 110 volts, are used. These are used as a night system only and, like the other systems, has its disadvantages, especially in foggy weather when used in a locality where a group of ships are at anchor displaying their many lights. L 4 SO GILBERT BOY ENGINEERING For sending messages by blinker the General Service Code is used. THE ACETYLENE LANTERN The standard night signal equipment used by the Army is the acetylene lantern. Acetylene is a pure hydrocarbon gas, and is produced in the signal lantern by bringing water into contact with calcium car- bide. The illumination resulting is about 1900 candle power and, with the exception of the searchlight, the acetylene lantern furnishes the most powerful form of night signaling. The range obtainable by this type of lantern is as much as ten miles with naked eye, and with a 30-power telescope the flashes can be read for thirty miles. On dark and cloudy days this lantern can be used for day signaling at a distance of one-half to three-quarters of a mile. SEARCHLIGHT SIGNALING The most powerful night system used is the searchlight, which is equipped with a shutter and operated by a key. This method of signaling is used by coast artillery corps and most commonly by the Navy. While it is essentially a night system, it is also used in day sending, and ships at sea in ordinary weather have been able to send messages for distances up to ten miles. THE HELIOGRAPH The heliograph is an instrument designed for the purpose of transmitting signals by means of the sun's rays. The sun being the most powerful light in existence, heliograph flashes can be sent farther than by any other method of visual signaling. When the day is clear and the sun's rays intense, GILBERT SIGNAL ENGINEERING 51 heliograph signals can be read up to forty or fifty miles, and even greater distances are on record. However, the normal range is around twenty-five miles, and to obtain longer distances it is usually necessary to operate from a large hill or mountain peak. The principal disadvantage to heliographing lies in its de- pendence upon the sunlight. The advantages are portability of equipment ; great range signals can be exchanged ; the rapidity of sending; and most important of all is the fact that your signals cannot be observed by others unless they happen to be on the line of flash between the sending and receiving station. Heliograph instruments vary in design according to the or- ganization using them, but all are alike in principle. The chief parts of the equipment for a station consist of one sun mirror, one station mirror, a shutter arrangement of some sort for inter- cepting the flashes and a device for directing or sighting flashes on receiving station. The Heliograph and Theory. Every boy has at some time taken a small pocket mirror or bright piece of metal from which he has reflected the sun's rays on a shadowed wall. The result on the wall is a bright sun spot or flash which can be moved at will by slightly shifting the mirror. As this flash is the im- portant factor in heliographing, it must be produced and di- rected at the receiving station with a great deal of skill. The mirrors used in heliographs are usually not over 4 or 5 inches square. Two mirrors are made necessary by the posi- tion of the sun at time one is sending. When the sun is at right angles to the line joining the two stations, only one mirror is used the sun mirror. With sun at rear of operator, the two mirrors are required. With one mirror the flash is reflected directly from it to re- ceiving station and with two mirrors the flash is reflected from 52 GILBERT BOY ENGINEERING the sun mirror to the station mirror and thence to the receiving station. (See Figure 11, A and B.) How Heliograph Operates With One Mirror. The sun mirror has in center a small peep hole or unsilvered spot about one- quarter inch in diameter. The sighting device is about 6 or 8 inches to front of the mirror. An upright rod is generally em- ployed which can be moved up and down; the rod sets parallel with edge of mirror and has a round disc on an arm which when turned at right angles to rod falls in line with center of mirror. To direct the flash accurately on distant stations, the operator sights through the peep hole in rear of mirror and adjusts disc so that the peep hole, disc and distant station are on an exact line. Then the sun mirror is adjusted on its horizontal axis only, so that the "shadow spot" cast by peep hole falls exactly on sighting disc. (The shadow spot can be found by placing a piece of paper between mirror and sighting device.) After "shadow spot" is located on disc the flash is visible at receiving station. (See Figure 12.) How Heliograph Operates With Two Mirrors. The sun mir- ror is faced towards the sun and the station mirror towards FIG. 11 GILBERT SIGNAL ENGINEERING 53 TS STA. SHADOW *SC OR JlONTlM* Btvice FIG. 12 receiving station. The station mirror has a paper disc pasted on its face at the center. The sun mirror is adjusted so that the whole of the station mirror is reflected into it and the unsilvered spot and reflection of paper disc accurately cover each other. To sight flash on receiving station the reflection of the distant station will be seen in station mirror and, by adjusting this so the disc covers the reflection of distant station, the flash will then be accurately in line. Intercepting the Flashes. The method of intercepting flashes in heliograph is either with the improved shutter with leaves operated by a key or with a single shutter held in the hand. In either case uniformity of movement should be maintained. Be- cause of the distances it is always advisable to count slowly three times for a dot and six times for a dash. Backgrounds. Dark backgrounds should be selected when possible for heliographing, as signals can be more readily dis- tinguished. To locate a distant station when its position is unknown, take 54 GILBERT BOY ENGINEERING the station mirror and direct it towards the horizon, playing it in slowly from right to left several times. If no response is FIG. 13 U. S. Marines sending a heliograph message. Courtesy of U. S. Marine Corps received, direct it at a point near the home station, and repeat this same process. As a result of this method you will usually locate the station. GILBERT SIGNAL ENGINEERING 55 If position of each station is known to the other, the station ready first will direct its flash upon the distant station so that that station may be able to adjust its flash to answer the signals. In heliographing, the sun's movement has to be watched care- fully and adjustments made often. In the case of well trained signalmen these adjustments can be made without "breaking" a message. The heliograph is best operated by two men. Heliograph flashes are sometimes very hard on the eyes; therefore it is always a good plan to smoke the lenses of the telescope a little when its use is necessary. THE ARDOIS SYSTEM The Ardois System for night signaling consists of a display of red and white incandescent lamps which indicate the characters of the General Service Code. The lamps are arranged in four units, each unit consisting of a red and white lamp. The units are placed an equal distance apart and usually suspended in a vertical position from a mast, yardarm or staff, in which case characters are read from top downward. When it is necessary to place lamps horizontally they are read by sender from right to left, and in case of receiver from left to right. A red lamp indicates a dot and a white lamp a dash. The lamps are operated by a keyboard. The letters of General Service Code are made by a single display; for example, A which is . would be made in the Ardois System by a display of the red light of the top unit and the white light of the next unit below. The letter B which is ... would be expressed by a white light from the top unit and the next three units below would be red. Chart 8 gives alphabet for the Ardois System, also conven- tional signals and numerals. The numerals of General Service Code cannot be used in the 56 GILBERT BOY ENGINEERING Ardoti Alphabet A urr>e 6 B <} 4 > > c i > > D > KEPEAT i > > 4 > F o G j ^ ^ H < 4 i i I 4 < > > J | 41 n i ^ ^ i > J K NE6ATIV2 6 6 L < c 4 4 i > > 1 M 1 M ANNUL- ^ 4 i l O INTEffROO | P d Q.i | i R.2^ 4 < > ) S-3 4 4 > > T.* 6 O 4 < i LCP&E < > 4 > Us ^ V.e 1 < 1 1 W.7 4 ( ^ > X-8 ( < s > Y.9 | O 1 < > J 4 s> { i ^ ) J Z.O J INTERVAL ( J CORNET < 4 i LETTERS FOLLOW i i | 5IGNAL5 FOLLOW t t FLASHCD ( i J 553&r 1 < [ STCA.VY ^ i J SSSXr ? CHART 8 GILBERT SIGNAL ENGINEERING 57 Ardois system as the expression is limited to four lamps. There- fore, numerals are made by giving secondary meanings to let- ters of the alphabet as shown on the chart. To make a numeral, display the letter by which it is indicated, and blink or pulsate the upper light. In the case of letters which indicate conventional signals the upper light is pulsated. The letter R is an exception to this. When pulsated it signifies Number 2, when flashed it is the con- ventional signal for "acknowledge." The interval is made once to indicate end of word, twice for end of sentence and three times for end of message. When interval is displayed and upper lamp pulsated it is a "Designator" signal. The general call to attention is a steady display of cornet WWWW. The cornet is not used, however, if call letter of station desired is known. In answer to a call, display call letter of station, the calling station then proceeds with message. To indicate that an error has been made in the message make "interval," the "error," then "interval" and then begin with word in which error occurred. The letter R flashed acknowledges the receipt of a message. When the Ardois System is in use, it is advisable to extin- guish all nearby lights which are liable to cause confusion in signals. The Ardois System is authorized for use by both Army and Navy. THE VERY SYSTEM The Very System of night signaling is used by Army and Navy, its use is mainly confined to signals of extreme impor- tance or when distance is great. The signals are made by firing red and green stars in the air by means of a pistol which has a barrel similar in gauge to 58 GILBERT BOY ENGINEERING the shotgun. The cartridges firing the stars are like the shells of a shotgun. This system is based on the dot and dash code, a red star rep- resenting a dot and a green star a dash. This system, however, is practical only for use with Army and Navy codes and there- fore is not of any service to a boy. Chapter VI TELEGRAPHY, RADIO-TELEGRAPHY AND TELEPHONY All of these non-visual forms of signaling are used by the signal corps of every modern army. They are also the common means of communication in everyday commercial life. In all of the above methods of signaling the use of electrical currents are necessary along with special instruments for re- ceiving and transmitting messages. The theory of electric currents is a study in itself. This subject is covered in the Gilbert Electrical Manual, and any boy wishing to acquire a knowledge of electricity and to apply the theory to his apparatus can do so by consulting Gilbert Manual of Telegraphy or the Gilbert Book on Radio Engineering. The writer will confine himself to the operative side of signaling, which includes the code and proper form of handling messages over these systems. TELEGRAPHY An American, Samuel F. Morse, invented the first working telegraph instrument in year of 1835. This instrument was the recording or writing type, that is, it made marks on strips of paper of dots and dashes which could be spelled into a mes- sage. The recording instruments are now obsolete and all telegraphy is conducted by sounding instruments, which spell out messages by means of sharp "clicks." THE AMERICAN MORSE CODE The American Morse Code is used on all land telegraph lines and short cables. It is also the official code of the Army for (59) 60 GILBERT BOY ENGINEERING AMERICAN MORSE -CODE. ALPHABET A mm B C D mm E F mmm Gr mmmmm H I U K mm. mm U w M 323 ME? N 009 O P Q ooze* R 8 ee T mm U V W von X Y 2 SL e NUMERALS 1 33caa 2 3 6 6 7 ao9a 9eMtCQLON POUNXJ3, STCRLlNCr CPX> CONVCMTIOMAL. SlOMALS Attention all opevdtova C9) ..-. ~Ple3.se sl&vt ttw (orj u)heve skill I start . , . . C4 ) Zifer^ ^ Ttit&ide Ctnin) .. 7 iinderst&tid, COK) ..... Busy on other zit*e* C25) .,.. -, COM) ..... ... (BK) . NOTE / A&bvetfialiotta saxne as on CHART 9 GILBERT SIGNAL ENGINEERING 61 electrical signaling on military telegraph lines, short cables and field lines. This code is written on Chart 9. Every signalist should familiarize himself with this code and learn how it differs from the General Service Code. The beginner should thoroughly commit to memory the signs representing the letters of the alphabet, the numerals and a few of the principal punctuation marks. The remaining characters can be learned afterwards as they are not needed by a beginner. The Morse Code is composed of seven elements : (1) The dot; (2) the dash; (3) the long dash; (4) the space; (5) the space between letters ; (6) the space between words and (7) the space between sentences. The dot is made by pressing the telegraph key down for the smallest fraction of a second and then immediately releasing it. The result on the sounding instrument is a "click-click" very close together. The making of a dot involves time, therefore the dash is equal to two dots and to make this the key is held down accordingly. A "click click" sound results. The long dash is equal to four dots, thus: "click click." The ordinary space between elements of letters is equal in time to a dot, between the letters themselves it is equal to two dots. The word space is equal to three dots and the sentence space is equal to six dots. Correct Way of Using the Key. The most successful manner of operating the telegraph key is to let the forearm rest easily upon the table, grasping the key as shown in Figure 14. The wrist should be well above the table, the forefinger curved, but not held rigid. Let the thumb rest on the edge of knob so that a slight control of the upward motion is obtained. The raising spring should assist the upward motion but should never be permitted to control it. Avoid tapping upon the key. The 62 GILBERT BOY ENGINEERING skilled operator will manipulate it by a muscular action of wrist and ringers. Elementary Practice of Code. Constant practice of making dots with uniformity and precision must first be acquired, then dashes, then grouping of dots and dashes to form letters and words. The beginner should commence by making letters slowly, giving proper ratio of time to the elements of each letter. Speed will come in time by persistent drill. The most difficult letters of the code are C O R Z Y and S, termed the space letters; and if spacing in these letters is not carefully timed they will be readily confused with such letters as H I P and L. The letters J and K, also numerals 9 and 7, are difficult letters, Care should be given not to separate J into a space which would result in a double N. The usual tendency is to make an F too long and an L too short. Practice transmitting from any miscellaneous manuscript at hand. This will always test the skill of an operator. RECEIVING TELEGRAPHY Receiving is of course more difficult to acquire than sending and is mastered best by having an experienced operator send or FIG. 14 GILBERT SIGNAL ENGINEERING 63 to the beginner slowly, increasing the speed as learner becomes more proficient. Proper Form of Transmission. A telegraph message like all visual messages must be checked by the sender. All words and figures written in the address, body of message and the signature are counted. Of course To and Sig. are not counted as they are only indicative terms used by operator. In counting the check of a telegraph message, whether in plain English or code, groups or initial letters are counted as one word. Abbreviations for names of places, cities, towns and states are counted as one word, as if written in full. This rule applies also to any other abbreviations. Figures, decimal points, bar of division and affixes to numbers, such as d, st, nd, th and rd will each be counted as a word. RADIO-TELEGRAPHY Radio-teiegraphy or wireless, by which term it is more com- monly known, was invented by -Marconi in 1901. Since that time there has been developed many improvements, which make the transmission of messages by wireless almost as practical as by telegraph lines or cables. Wireless messages are spelled out by use of the International Morse or General Service Code (see Chart 1), the operator using a key like that used in telegraphing. The result is some- what different from telegraphing, as wireless instruments have a humming or buzzing sound instead of a "click." The char- acters of the alphabet are made up of short and long buzzes. The receiving is done through phones. While wireless is under the control of the Navy in the United States the government does not have exclusive use of it. A great many commercial stations have been established and in 64 GILBERT BOY ENGINEERING FIG. 15 Boy Scouts of Hartford, Conn., learning the theory of wireless. Courtesy of Boy Scouts of America this country alone there are thousands of boy experts using wireless, and enthusiasts are being added to the list daily. Note : For conventional signals other than in General Service Code see Gilbert Book on Radio Engineering. TELEPHONY The most widely used of all electrical signal systems is the telephone, invented by Alexander G. Bell, an American. The telephone is so common in our everyday life that most of us do not stop to consider the interesting principles involved. Color Charts GILBERT BOY ENGINEERING INDEX Chart 10 Flags of the International Code Chart 1 1 Ship Call Pennants Call Flags Chart 12 Special Flags of the U. S. Navy Chart 13 Personal Flags Chart 14 Weather Signal Flags GILBERT SIGNAL ENGINEERING FLAGS OF THE INTERNATIONAL CODE [I U CD H ffi CODE FLA& AND ANS. Q CHART 10 GILBERT BOY ENGINEERING SHIP CALL PENNANTS R COCOR OF PENNANTS i& BASED ON DOT AND DASH CODE X C T U K _ Q OASH.YELLOW DOT , KED SLOB , ere ATS p*eeeoiMO COL. CALL FLAGS 6 PHI ffl w CHART 11 GILBERT SIGNAL ENGINEERING SPECIAL OF THE U.S. NAVY EB NUMERALS Q-ENERAL RECALL (JOAT RECALL J PREPARATORY AFFIRMATIVE ANNULLING INTER ROflATORT DISPATCH BREAK DOWN MAN OVERBOARD 1ST. REPEATER Bo. REPEATER REPEATER QUARANTINE SQUADRON CONVOY POSITION DIVISION ** *^ CHART 14 GILBERT SIGNAL ENGINEERING 65 In speaking, the vocal cords cause air vibrations, which, fall- ing upon the eardrum are recognized by the auditory nerves as speech. When these vibrations are transmitted into a telephone instrument, they are caught by the sensitive diaphragm, changed into electrical vibrations, carried along the telephone wire to the receiving station and reproduced. Note: See Gilbert "Sound Experiments" and Manual on Telephone. THE TELEPHONE FOR SIGNAL PURPOSES When signal stations are connected by telephone, messages are of course sent by this means, it being much more handy. L 5 FIG. 16 U. S. Army Signal Corps field radio station somewhere in France. 66 GILBERT BOY ENGINEERING The difficulty arising in telephonic messages is the confusion of certain letters of the alphabet having like sounds when spoken by word of mouth. To provide a ready means of distinguishing similar sounding letters, a code of conventional signals is authorized for military purposes and should be used especially when codes are being sent. These conventional signals are as follows: A Able N Nan B Boy O Oboe C_Cast P Pup B_Dog Q Quack E Easy R Rush F Fox S Sail G George T Tare H Have U Unit I Item V Vice J Jig W Watch K King X X-ray L Love Y Yoke M Mike Z Zed To give an example of the proper use of this code we will suppose an important message is being telephoned to a station and the receiving operator cannot clearly understand certain words such as directory, or the word translation. To make these words clear the operator would spell directory out slowly Dog-Item-Rush-Easy-Cast-Tare-Oboe-Rush-Yoke. The word translation would be spelled out likewise. From this code a clear understanding would undoubtedly result. GILBERT SIGNAL ENGINEERING 67 THE SERVICE BUZZER The Service Buzzer is a portable piece of signal equipment especially adapted to the needs of the Army Signal Corps. It can be readily attached to either telephone or telegraph lines and used as a telephone or for sending Morse or General Service Code telegraphic signals. When service buzzer is used in the latter form the signals are received in a telephone receiver in form of a high-pitched hum very similar to wireless signals. Signals have been exchanged between two buzzer outfits even after wire connecting the stations has been cut in. The instruments were, of course, grounded. The mechanism of the buzzer is very simple, so simple in fact that any boy can make a practical outfit for Field Service Signaling by following the suggestions given in this book on page 102. Chapter VII THE SIGNAL TOWER The Tower of Babel served as a rallying point and in all prob- abilities was the first signal station. Later examples of old sig- nal towers are those built by the Chinese along the wall of China. Today, how- ever, the modern sig- nalmen do not build such substantial tow- ers, as the up-to-date armies are mobile and consequently when a signal tower is re- quired a portable one or a hand-made affair, which can be erected in a few minutes by field signal troops, is used. The boy signalist wanting to establish a visual station must first select the site so it is perfectly in view of receiving station and with a uniform FIG. 17 background for all Signal tower erected at a boy Scout Camp. Cour- ci'rrnplQ TVii* tesy of Boy Scouts of America Signals. 1 ne (68) _ GILBERT SIGNAL ENGINEERING _ 69 station is the best judge of the proper location and background for the signal tower. In locating a military station secrecy is of vital importance, and for this reason the tower is usually camouflaged by shrub- bery or erected behind foliage so the platform of tower is barely exposed. The following table gives distances of the visible horizon or how far an object at sea level can be seen. When observer's eye is : 5 feet above, the distance is 2.7 miles 10 " " " " " 3.8 " 15 " " " " 4.7 " o/~v (( (S t< ft it C A f( 25 " " " " " 6.1 30 " " " " " 6.7 " or Z7 -fr34 3Z tt 37 L* 4-1* 5-0 4-Si HOW TO MAKE A CIPHER OUTFIT A practical, yet simple cipher can be made by first obtaining several pieces of ordinary flat pic- ture moulding like those shown in Figure 21. These pieces will slide parallel to each other; one piece should be at least 14 or 15 inches in length, while the other can be just half that length. Next take white ruled paper and paste along flat surfaces of moulding, the ruling or lines of paper should be about ^ inch apart. Fifty-two spaces are necessary for the long piece and the alphabet is written twice, back- wards, in small letters, starting from top as shown in Figure 22, these letters are numbered from 1 to 52. FIG. 22 76 GILBERT BOY ENGINEERING The short piece of moulding is lettered with capitals starting with A at top, going down or the reverse of the lettering on the longer piece, which starts at bottom going up. The number 10 on the small piece and the opposite number on the long piece are used as keys to cipher. Method of Using Cipher Outfit. By referring to Figure 22 it will be seen at once that to change the cipher all that is neces- sary is to shift the small piece of picture moulding up or down. Each sending and receiving station would have this outfit handy, and to send a message the following procedure should be kept in mind. Encipher or, that is, put your message into cipher from capi- tals to the opposite small alphabet. To decipher a message at receiving station use the reverse method. To give the receiver the proper key to cipher; this can be done by signaling the key in the preamble of your message ; for example, the message : "WE BREAK CAMP AT SUNRISE" would be sent, if taken from Figure 22, as follows: (Key) 1027 QI LVIMC KMAX MT USZVEUI. Chapter VIII MARITIME SIGNALING United States Maritime Signaling is divided into two branches : that of the Merchant Marine and that of the Navy. The signal methods of the Merchant Marine apply in all cases to privately owned yachts, power boats and other small craft having use for a signal system. To be well versed in Maritime Signaling it is necessary for a signalist to know wherein the methods differ between U. S. merchant vessels and ships of the U. S. Navy. U. S. Merchant Marine Signaling. The methods of signaling in the U. S. Merchant Marine are based entirely on the Interna- tional Code of signals, which is the result of many years of work on the part of the International Marine Conference. The International Signal Book is used by all vessels through- out the world, both merchant and men-of-war, thus enabling all ships to carry on communications by signals, even without the knowledge of one another's language. Every signal in the International Signal Book has the same meaning in any language. Signals are sent from the International Signal Code by means of the following systems : Flag Hoists, International Morse Code, which is same as Gen- eral Service Code, International Flag Waving, Colombs Sound and Flashing System and International Distance Signals. The most general method of signaling by vessels is by means of flag hoists in which the International Code flags are employed. (77) 78 GILBERT BOY ENGINEERING There is nothing that gives a poorer impression to expert signalmen, or those who know, than to observe the misuse of flags in signaling. For this reason the writer will acquaint you in a general way with a few nautical terms relating to flag hoist signals and correct form of handling flags. FLAGS AND CORRECT WAY OF USING The Hoist of any flag is the side fastened to flagstaff or line holding it. The Fly of a flag is at right angles to the hoist. (See Figure 23.) A Hoist of flags is a number of signal flags on one line or hoist. The lines by which a signal flag or flags are hoisted are called halyards. That part of halyard which is attached to upper hoist of flag running through pulley or block is termed the down haul. That part of halyard which is connected to the lower hoist of the flag or flags is termed the tail. (See Figure 23.) Flag signals on merchant ships are usually hoisted to the most convenient position on the yardarm or mast from which signals can best be seen and distinguished. However, on most of the FIG. 23 larger ships a special signal GILBERT SIGNAL ENGINEERING 79 CARKICK BEND FIG. 24 yard is used on the foremast which is situated ahead of the ship's funnels. The signals are not then obscured by smoke ex- cept in a case where receiving ship is dead astern. Signal flags are flown from either Port (left side of a ship) signal yardarm, or Starboard (right side of a ship) signal yard- arm according to position of the receiving ship. A flag is said to be close up when hoisted to its limit on a yardarm or mast and at dip when only hoisted two-thirds of the way up. (See Figure 25.) The Peak of a mast is extreme top point. All signal and special distinguishing flags vary in size and shape; however, in regard to shapes, a way of classifying as to proper names can be found by consulting Figure 27. Signal flags are fastened on the halyards by means of a ring at the upper end of the hoist of flag and a snap hook at lower end. They may be tied to halyards by means of a single carrick bend. (See Figure 24.) The last method is clumsy and slow. All of the up-to-date merchant lines and navies that have a great many signals to handle use rings and hooks. FLAGS OF THE INTERNATIONAL CODE AND HOW USED The International Code flags are twenty-six in number one for each letter of the alphabet and also a code pennant, all of which are pictured on Chart 10. (See special section of colored fla^s.) 80 GILBERT BOY ENGINEERING One-flag signals B, C, D, L, P, Q and S hoisted singly have a special significance. The code pennant over each indicates that they are signals of a general nature and of frequent use. Code flags hoisted singly after numerals signal Number 1 refer to numeral table in Code Book, as do also two-flag signals with code pennant hoisted under them. Two-flag signals without code flag are urgent and important signals; with the code flag hoisted over them they are time, latitude, longitude, barometer and thermometer signals. Three- flag signals express points of the compass, money, weights and measures and also other signals required for general communica- tion. Four-flag signals with a burgee (A or B) uppermost are geographical signals; with C uppermost they are spelling or vocabulary signals; with G uppermost they are names of men- YARD FIG. 25 GILBERT SIGNAL ENGINEERING 81 of-war; with a square flag uppermost they are names of mer- chant vessels. The following are meanings given single flags already men- tioned : B. Am taking on (or unloading) explosives. C. Yes or affirmative. D. No or negative. L. I have (or have had) infectious disease aboard. P. I am about to sail ; all persons report on board. Q. Have clean bill of health, but liable to quarantine. S. I want a pilot. Single flags are sometimes used as signals from a towing ship to ships in tow ; the meanings when used thus do not, how- ever, correspond in any way to above signals. METHOD OF SIGNALING WHEN NO OTHER SHIPS ARE IN SIGHT Example : Ship A wants to signal ship B. Ship A will hoist her ensign (national colors) over the code pennant but not on the same halyard. If hoisted at same mast as succeeding signal the methods will interfere. As soon as ship B makes out the attention signal she will answer by hoisting the code pennant at dip ; then ship A proceeds with signals, first hauling down the code flag, and when completed ship B acknowledges by hoisting the code pennant close up and leaves it there until ship A hauls down the hoist of signals after which she lowers it to dip, and awaits the next signal. When ship A has completed her signals she hauls down the ensign and the other ship hauls down the answering pennant (code pennant). L -6 82 GILBERT BOY ENGINEERING All flag hoists are read from top down and never exceed four to the hoist. In case several ships are in sight and ship A wishes to signal ship B, she will attract attention of B by either of two ways; the first, is to hoist B ship's distinguishing letters or, second, to hoist the two-letter signals which indicate direction the ship she wishes to call is traveling. All vessels are supposed to display their distinguishing call letters when passing at sea. DISTANT SIGNALS When in consequence of distance, wind or weather preventing the code flags from being seen, an alternative method of signal- ing is used, which is known as distant signals. There are three ways of making distant signals: 1. By means of the Fixed Coast Semaphore. 2. By means of square flags, pennants and whefts. 3. By means of cones, balls and drums. Calm weather and when wind is blowing from and towards the receiving station are the reasons that make it difficult to make out the colored flags of the International Code. For this same reason the method of distant signaling by means of square flags, pennants and whefts is not as preferable as by the cones, balls and drums. A wheft is any flag tied in center to halyards ; therefore this system is mostly used. Chart 15 gives the distant signal alphabet by balls, cones and drums. The shapes are made by stretching canvas over pieces of light wood or metal forms, the canvas is as a rule then painted black. The signals are made from International Signal Book and hoists are read from top down same as the flags. GILBERT SIGNAL ENGINEERING 83 DISTANT SIGNAL ALPHABET M N U CHART 15 Q 84 GILBERT BOY ENGINEERING For convenience in their use the shapes representing the let- ters have been arranged in numerical order. The letters A to G begin with one, the letters H to U begin with two, and the let- ters V to Z begin with three. Distant signals by Fixed Coast Semaphore are made by a sem- aphore machine. The position of the arms indicate numbers which are translated from the International Signal Book. This method is only employed by shore stations and not by ships. INTERNATIONAL FLAG WAVING SYSTEM The International Flag Waving System is done by a single stick wigwag flag and the International Morse Code is used. However, the method of making dots and dashes is different from the U. S. Army and Navy Wigwag System. The dot is made by a short sweep of flag over the head of sender and a dash by a long swing of the flag. Chapter IX U. S. NAVY FLAG SIGNALS The flag signal system of the Navy is in all probability the most important of all day signal methods. It has the advantage over the two-arm semaphore, either hand flags or machine method, and the wigwag which are the other day systems used by the Navy and which have already been explained. The advantage of flag signals in the Navy is the great range and its adaptability to fleet manoeuvering and battle tactics. The flag signals are made by hoists transmitting the Navy Flag Code, this flag code can also be sent by all the other signal methods used in the Navy. When flags are necessary for intercommunication between the U. S. Army and all merchant ships, the International Flag Code is used. The term "break" or flag is "broken" will come up in connec- tion with Navy flag signaling, so it will be well to acquaint you with the proper way of making up a signal flag for breaking. There are several ways to do this, but the following plan, if followed, will prove the most reliable : Figure 26 (A) shows a signal flag lying flat on the deck ready to be made up for the "break." To do this the flag is folded on dotted lines 1 and 2 and then rolled towards the hoist as in B, after which the tail line is laid on top of rolled flag in form of a loop. The free end of line is then wrapped securely around the roll and over the loop by a number of turns and again looped into the end of other goose neck (see C) and drawn tight, which serves to clinch the tail line. (85) 86 GILBERT BOY ENGINEERING The flag is then ready to hoist as in D, after which it can be broken by simply giving a sharp tug on the tail line. The foremast is principally used for signaling by naval ships, except in the case of a flagship which flies her signals from the FLAG- GILBERT SIGNAL ENGINEERING 87 main mast. The signal yards in either case are usually provided with three to six signal halyards on each port and starboard side. The peak of a mast on a naval ship is usually termed the truck. HOW NAVY SIGNALS ARE EXECUTED The General Signal Book of the U. S. Navy contains a list of signals known as the Navy Flag Code. This book is divided into various parts, some of which are very confidential and are in the hands of only the higher officers. The method of making the signals is alike no matter from what section or volume, as the meanings are arranged in alpha- betical order opposite the signals to be sent. The flags and pennants used in the Navy for making flag sig- nals are the alphabet flags of the International Code flags, except the code pennant (see Chart 10) and a number of special flags and pennants contained in Charts 11 and 12. While the alphabet flags of the Navy Code are same in design as those of the International Code, they have no connection whatever. A distinct naval feature is to call the flags by name rather than by letter, the name applied to the alphabet flags are able for A, boy for B, etc., same as the conventional signals used for telephoning on page 66. CALLS Each ship in the Navy is furnished with a call, which is a combination of two letters like ZL, PN, or AD. For sake of convenience the first letter of a ship's call repre- sents the group to which that ship belongs and the second letter the ship of that particular group. One set of flags is used for the group and another for the ship. 88 GILBERT BOY ENGINEERING GlLl&tl Obloti ee, FIG. 27 GILBERT SIGNAL ENGINEERING 89 The two-letter call of each ship is made by using one of the call flags and one of the call pennants. (See Chart 11.) In order to furnish calls to squadrons, divisions, etc., of a fleet additional flags are used for indicator flags and will be found on Chart 12 under the title, Squadron, Division, Torpedo Flotilla and Submarine Flotilla. The call of a particular ship wanted to take a message would be made (in case of a number of naval ships of various classes in immediate vicinity) by its indicator flag with call letters hoisted underneath. Where a general call or message is to be given to all ships within signal distance, the cornet flag is hoisted without indi- vidual call letters and all ships are required to answer. All naval vessels passing at sea always hoist their call letters. The answering pennant is used to answer all flag signals, and is hoisted from point best seen (at truck or either side of the signal yard) and is kept there until ship signaling hauls down the signal. The answering pennant is also used as a divisional point in making a numeral hoist. The alphabet flags from Q to Z are designated as numerals from 1 to respectively and are so indicated when the numeral flag precedes them on a hoist. The repeaters 1st, 2d and 3d serve to reproduce numeral hoisted above them. The first repeater would act as a repeater for the first flag, 2d repeater for second and so on. For example, the numeral 232 would be hoisted using the numeral flag fol- lowed by R(2), S(3) and first repeater. The numeral 2222 would be hoisted R(2) 1st, 2d, and. 3d re- peaters. The Preparatory Flag (L) means prepare to execute signal shown. It is also used as a time signal by the flagship or senior ship present, in which case it is hoisted at 6:55 A. M. and hauled down promptly at 7 A. M. It also indicates that the 90 GILBERT BOY ENGINEERING uniform of crew is same as yesterday. When hoisted at 7 : 45 A. M. over a numeral it indicates the size of the ensign (colors) ships are to hoist at 8 A. M. It is hauled down at 8 A. M. and all ships then hoist the national colors. The Interrogatory Flag (O) hoisted over a signal changes its meaning into the interrogatory form. The Affirmative Flag (P) when hoisted in answer to a signal means yes, or permission granted. The Negative Flag (K) when hoisted in answer to a signal means no, or request not granted. The Annulling Flag (N) annuls all signals at time display on the same mast, hoisted alone it annuls a previous signal which has just been made. The Quarantine Flag (Q) hoisted at foremast truck indicates ship is under quarantine or has an infectious disease aboard. The Guard and Guide Flag, when hoisted at fore truck in port between sunrise and sunset, indicates that that ship is charged with the guard duty for that day (a red truck light is used at night at foremast). When hoisted by a ship under way it indicates that that ship is to guide the formation. The guard flag is displayed on all the small boats belonging to the ship doing guard duty. The guard flag, however, is not dis- played in any way by a flagship if they are performing that duty. The Convoy and Position Pennant is worn at the foretruck of all ships on convoy duty; in formation, when hoisted at dip it signifies "I am temporarily out of position/' The Danger and Designating Flag hoisted alone means danger ahead; a compass signal under it signifies the direction from which danger is expected. The Dispatch and Breakdown Flag (I) wHen worn at main truck indicates that that ship is on dispatch duty; in fleet for- mation this flag is always kept rounded up ready to "break" at GILBERT SIGNAL ENGINEERING 91 foretruck and when "broke," it signifies a breakdown of ships machinery or the steering gear. In case of a man overboard it is "broken" and lowered at dip. The General and Boat Recall Flag. Hoisted alone this flag calls all the small boats back to their respective ship at once. When hoisted under a number it recalls only that boat or boats having these numbers. At night small boats are recalled by the display of I followed by boat numbers and the call letters of ship signaling. The Powder and Firing Flag (B) is displayed at the foremast of all naval vessels engaged in taking on board explosives, such as loaded shells, fuel oil or gasoline. The Meal, Full Speed and Flag Officer Leaving Pennant, when hoisted singly at the port yardarm by a ship at anchor, signifies that crew is at meal ; if hoisted at sea on same yardarm with the speed cone, it means one knot faster than standard speed; alone with speed cone it denotes full speed; and when hoisted under the flag of any flag officer it conveys the fact that that officer is leaving the ship. The Battle Efficiency Pennant is shown at the foremast (when ship is at anchor) of ship or ships which are authorized to fly same. The Battle Efficiency Pennant is awarded each year by the Navy to one ship in each of the battleship, submarine and torpedo boat class for excelling in gunnery and engineering for that particular year. The Church Pennant is hoisted over the ensign while divine services are being held, it is the only flag ever hoisted over the ensign for any reason whatsoever. The Red Cross Flag is an International flag flown by all hos- pital ships, their small boats and also flown at Naval Field Hos- pitals. The flag is flown at the bowstaff on ships. The Submarine Warning Flag is hoisted and flown by any vessel or small boat acting as a mother ship or fender to sub' 92 GILBERT BOY ENGINEERING marines, and it signifies that submarines are submerged or operating in that vicinity. U. S. NAVAL FLAG ETIQUETTE Every ship in the U. S. Navy carries a complete set of the various national ensigns of other countries. Some nations have two ensigns, each different in design, one for men-of-war and another for merchant vessels. In the case of the United States government the national colors are alike for both naval and merchant ships. The national ensigns of foreign countries are flown from the main mast of U. S. Naval vessels on occasions such as a visit irom the head of a foreign government or any other high officials, either diplomatic, military or naval. In American or foreign waters, on occasion of such a visit, the national ensign of the country the official represents is made up and "broke" at main mast as the visitor or visitors step aboard. At time flag is broken the saluting battery fires the proper salute that the visitor is entitled to. U. S. Naval ships upon entering a foreign port always "break" the national ensign of the nation visited and fire a salute of twenty-one guns. The salute is answered by the highest official present from either a naval vessel or a military shore station or fort. U. S. Naval ships passing other men-of-war or merchant ships at sea always dip the colors in answer to the same courtesies. It is customary for merchant ships of either U. S. or foreign countries to dip colors to the men-of-war first. However, in case of naval vessels meeting, the junior officer always dips first to his senior. No salutes are fired as a rule to naval officers of a rank lower than a flag officer, which in the U. S. Navy is a Rear Admiral or above in rank, except where an officer lower in rank may be acting in that capacity. GILBERT SIGNAL ENGINEERING 93 TIME FOR FLYING COLORS The time for flying of the national ensign on naval ships is given by the senior officer present. The size of colors to be used is also designated by signal. As a general rule the colors are hoisted at 8 A. M. in port and at the flagstaff at stern of ship with the proper ceremonies. At sea the colors are hoisted at the gaff (small spar projecting from the main mast). The colors are lowered at sunset with the same ceremonies, but at sea the colors are usually replaced after being lowered by a smaller ensign which flies all night, as do certain other special designator and personal flags. It is not customary to signal by means of flags before morning or after evening colors. The Union Jack is hoisted in port only and at jackstaff in bow. It is hoisted at morning colors and lowered at evening colors. The Union Jack hoisted at fore signal yard indicates there is a general court martial or court of inquiry being held aboard. When hoisted for such purposes a gun is fired. The Union Jack hoisted at foremast truck calls a pilot aboard. PERSONAL FLAGS Chart 13 gives the personal flags of the higher officers in U. S. Navy, along with special distinguishing flags of the naval militia and yachts. The President's Consular and flags of Secretaries of the Navy are used on any visit to a naval vessel by these officials. The personal flags of Admiral, Vice Admiral and the Rear Admirals are flown at the main mast truck of their respective flagships. The Blue Pennant of Senior Officer present is known by the ship having the senior officer of any group of naval vessels in the absence of a flag officer. All naval ships in commission fly the commission pennant at 94 GILBERT BOY ENGINEERING the main mast truck. This pennant really acts as a personal flag of the commander of the ship and in case of a flagship it is not worn, as the flag officer's personal flag signifies that that ship is in commission. The Naval Militia Distinguishing Flag is worn at foremast truck of all naval vessels loaned by the Navy department to a state for use of Naval Militia or Naval Reserves when such ves- sels are under command of Naval Militia or Reserve Officers. The Naval Militia Commission Pennant is worn at main mast truck on such ships, and in event of ship having a flag officer aboard his personal flag is flown instead at main truck. The rank of Commodore is the highest in Naval Militia. YACHT FLAGS .* It is required by law that all pleasure yachts and boats of more than 15 tons display the yacht ensign. This you will note by referring to Chart 12 is different in design from the national ensign and serves to signify when worn that that particular ship is a pleasure boat. Yachts fly all personal flags in a similar way as used in Navy. For signaling, they use all navy methods except Navy Flag Code. The substitute being the International Flag Code for flag hoist signals. Chapter X MISCELLANEOUS SIGNALS INTERNATIONAL LIFE SAVING SIGNALS 1. Upon the discovery of a wreck at night, the life-saving shore station burns a red light or sends up a red rocket to sig- nify "You are seen," assistance will be given soon as possible. 2. A red flag waved on shore by day or a red light or red rocket by night means "Haul away." 3. A white flag waved on shore by day or a white' light waved slowly or white rocket by night means "Slack away." 4. Two flags a white and a red waved at same time on shore by day, or two lights a white and red swung slowly or a blue light burned by night signifies "Do not attempt to land in your own boats, it is impossible." 5. A man on shore beckoning by day or two torches burning closely together by night will signify "This is the best place to land/' SIGNALS FOR A PILOT Any of the following when displayed from a ship will call a pilot : 1. The Jack, hoisted at the foremast. 2. The International Code pilot signal indicated by the alpha- bet letters P T. 3. The International Code flag S displayed alone or with code pennant over it. 4. The Distant Signal, with cone pointed upward, having above it two balls or oval shapes. (95) 96 GILBERT BOY ENGINEERING 5c At night, a blue light burned at intervals of about fifteen minutes or a bright white light flashed at short intervals just above the deck. 6. To signal for a tow boat place the National Ensign in main rigging just above the decks at intervals of one minute at a time. INTERNATIONAL DISTRESS SIGNALS, FOR DAY 1. A gun or other explosives fired at intervals of one minute. 2. The International Code letters N C. 3. Fog Signal apparatus sounded steady. 4. The Distant Signal consisting of a cone pointed upward, having either above or below it a ball or oval shape. INTERNATIONAL DISTRESS SIGNALS, FOR NIGHT 1. Gun or other shot fired every minute. 2. Flames of a burning tar or oil barrel. 3. Rockets or shells throwing stars any color at short inter- vals. 4. Foghorn sounded steady. The United States Weather Bureau is operated under the Department of Agriculture. The Bureau has many stations throughout the country as well as 142 stations on the Atlantic and Gulf Coasts and 46 stations on the Pacific Coast. Weather predictions are given out from these stations to all the newspapers, and bulletins are furnished to all Federal build- ings for posting. The inland stations have telegraphic connections with the coast stations and inform them of the approach of severe storms. The coast stations in turn notify mariners by means of flag signals and radio. GILBERT SIGNAL ENGINEERING 97 All the civilized nations of the world maintain a similar sys- tem in which their coast stations give information to ships. The Weather Signal flags may be seen by turning to colored Chart 14; at bottom of same chart are storm and -wind signal flags, along with night lantern signals. The Weather and Storm Signal flags when displayed on a flag pole are arranged to read from top down. When single hoists of several flags are made on a signal yard a small streamer is used to indicate the point from which signals are to be read. Temperature forecasts signals are made by using the weather flags, five in number four square flags and one pennant. The flags are displayed at weather bureau stations as fol- lows, and indicate weather predictions for next twenty-four hours, commencing at 8 P. M. of day the signals are made : 1. Square white flag indicates clear or fair weather. 2. Square blue flag indicates rain or snow. 3. Square flag white on upper half and blue on lower half in- dicates local rains or showers will occur and that rainfall will not be general. 4. Square white flag with black square center indicates the approach of a sudden and decided drop in temperature a cold wave. 5. Black pennant is used to refer to temperature and has no meaning hoisted alone. In no case is it ever hoisted with the square white flag with black center. (Cold wave flag.) The black pennant hoisted above square white flag, blue flag and white and blue flag indicates warmer weather along with the regular indication that that flag stands for. When hoisted below any of these flags it means colder weather. Storm and Wind Signals. The warnings adopted by the U. S. Weather Biireau to announce the approach of wind storms are as follows : (See bottom of colored Chart 14.) L 7 98 GILBERT BOY ENGINEERING The Small Craft Warning. A red pennant indicates that moderately strong winds that will interfere with the safe opera- tion of small craft are expected. No night display of small craft warnings is made. The Northeast Storm Warning. A red pennant above a square red flag with black center displayed by day or two red lanterns, one above the other, displayed by night indicates the approach of a storm of marked violence with winds beginning from the northeast. The Southeast Storm Warning. A red pennant below a square red flag with black center displayed by day or one red lantern displayed by night indicates the approach of a storm of marked violence with winds beginning from the southeast. The Southwest Storm Warning. A white pennant below a square red flag with black center displayed by day or a white lantern below a red lantern displayed by night indicates the approach of a storm of marked violence with winds beginning from the southwest. The Northwest Storm Warning. A white pennant above a square red flag with black center displayed by day or a white lantern above a red lantern displayed by night indicates the approach of a storm of marked violence with winds beginning from the northwest. Hurricane or Whole Gale Warning. Two square red flags with black centers, one above the other, displayed by day or two red lanterns, with a white lantern between, displayed by night indicates the approach of a tropical hurricane, or one of the ex- tremely severe and dangerous storms which occasionally move across the Great Lakes and Atlantic Coast, Chapter XI HOW TO MAKE SIGNAL APPARATUS Flag Making. The most suitable material for flag making is either galatea or calico. The color and dimensions of the cloth are dependent upon type of flag wanted and the size. The tools necessary are a straight-edged yardstick or ruler, a soft pencil or chalk for marking off the cloth, an old safety razor blade or a pair of scissors for cutting and needle and thread for stitching flag together. You can get your mother or sister to do all sewing required on the sewing machine. Making Wigwag Flags The standard dimensions of the wig- wag flags used by the Signal Corps are the 3-foot, 9-inch square flag with 12-inch square center and the 2-foot square flag with 8-inch square center. The 2-foot size flag is large enough for most signaling and it will be best for you to adopt this size or possibly smaller as the larger type is only useful in case of extreme distances. The 12-foot staff necessary to carry a flag this large is very hard to handle. The 2-foot wigwag flag needs a staff 5j4 feet in length. If flag is made smaller than this the staff can be made shorter and the center square can be cut down to a proportionate size. The color combinations for wigwag flags are turkey red and white, or scarlet and yellow. Blue and white is sometimes used and is very good, but red and white is the best. Flags can be made up using any of above combinations, al- ternating the colors of the body of the flag and center for use against different backgrounds. (99) 100 GILBERT BOY ENGINEERING FLAG MAKING CHART 16 GILBERT SIGNAL ENGINEERING 101 No. 1 of Chart 16 shows the proper way to lay out a wig- wag flag. The cloth can be tacked to any flat surface and, with a ruler and pencil, a square can be marked off the exact size wanted. Lines can then be drawn from corner to corner as shown. This serves to he*lp; get ,the square > in the exact center. The cloth can then be cui ai'burtd the dotted lines, which should be about J4 or ^ itich.{rQm;