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 VjrAS 
 
 INSTRUCTIONS IN 
 MILITARY SIGNALING 
 
 GIDDINGS 
 
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INSTRUCTIONS IN 
 
 MILITARY SIGNALING 
 
 FOR THE USE OF THE 
 
 REGULAR AND VOLUNTEER ARMY 
 
 AND THE ORGANIZED MILITIA 
 
 OF THE UNITED STATES 
 
 BY 
 
 Captain HOWARD A. GIDDINGS 
 
 BRIGADE SIGNAL OFFICER, CONNECTICUT NATIONAL GUARD 
 AUTHOR OF MANUAL FOR CYCLISTS, ETC. 
 
 SECOND EDITION 
 
 h 
 
 NEW YORK 
 
 D. APPLETON AND COMPANY 
 
 1899 
 
Copyright, 1896, 
 
 bt d. appleton and COMPANT. 
 

 State of Connecticut, 
 Adjutant-General's Office, 
 
 Hartford, November 12, 1896. 
 General Orders, No. 19. 
 
 (Extract.) 
 The manual of Instructions in Military Signaling, pre- 
 pared by Major Howard A. Giddings, Brigade Signal Officer, 
 Connecticut National Guard, is hereby adopted for use of 
 the Connecticut National Guard. 
 
 By order of the Commander-in-Chief. 
 
 Charles P. Graham, 
 
 Adjutant- General, 
 Official : 
 
 William E. F. Landers, 
 
 Assistant Adjutant- General, 
 
 M277809 
 
PREFACE. 
 
 this book has been induced by 
 ensed and practical Manual of 
 ipted to present requirements 
 
 aiental principles of signaling 
 'ed, changes in the code, im- 
 is and methods, and the ad op- 
 means of transporting signal- 
 ive rendered much of existing 
 obsolete. 
 
 gnals and Gallup's Handbook 
 lave both been consulted, and 
 ely followed ; but it is believed 
 nmch that is new, and which 
 t time in print. 
 
 rein for the use of the helio- 
 
 'eviated from those of Captain 
 
 il Corps, U. S. Army, author- 
 
 . A. 1888, with such changes as 
 
 the Myer system of signaling necessitates. 
 
 The instructions in military photography are large- 
 ly taken from the Manual of Photography, by First 
 Lieutenant Samuel Reber, Signal Corps, IJ. S. Army. 
 The chapter on the use of the bicycle and transporta- 
 tion of apparatus is based on the results of five years^ 
 5 
 
 Signal Flags. 
 
 M. R. S. — Signaling 'by 
 fiag-s, as the term is now 
 universally understood, 
 c\-as invented in the year 
 1854 by Surgeon Myer of 
 the United States army. 
 Before Surgeon IVEyer's 
 invention the only flag 
 signaling was by color, 
 but realizing the Inade- 
 quacy of such a mode of 
 conveying information, 
 Dr. Myer studied out the 
 system of "wigwagging" 
 or talking by making 
 motions with the flag, a 
 sort of deaf and dumb 
 telegraphy, which has 
 since been adopted by 
 pretty nearly all the na- 
 tions of the world. 
 M« * * 
 
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6 PREFACE. 
 
 experience with the bicycle in the Signal Corps of the 
 National Gruard of Connecticut — the first State to es- 
 tablish and develop a signal corps, and by whose troops 
 the bicycle was first used in the military service in the 
 United States. 
 
 Instructions in electrical signaling have been pur- 
 posely omitted. No standard field equipment for either 
 telephoning or telegraphing has yet been adopted for 
 the army, and it is useless to attempt to lay down in- 
 structions for the use of experimental or temporary 
 apparatus. Such instructions for the operating of per- 
 manent telegraph lines as could be included in a work 
 of this size would be of little value to the average sig- 
 nalman, and still less to the professional operator, 
 upon whom we must always rely for the operation of 
 such lines. 
 
 It is intended to include herein such practical in- 
 structions in military signaling as will best insure the 
 successful practice of the art by the Organized Militia. 
 
 Howard A. Giddings, 
 Major, Brigade Signal Officer, 
 Connecticut National Guard. 
 
 Hartford Connecticut, October 1, 1896. 
 
CONTENTS. 
 
 PAGE 
 
 The Myer System of Army and Navy Signaling : 
 
 Alphabet . . , -9 
 
 Numerals 9 
 
 Abbreviations 9 
 
 Conventional Signals 10 
 
 Code Calls .10 
 
 Instructions for using the System . . . .10 
 To signal with Flag, Torch, Hand Lantern, or Beam 
 
 of Search Light 11 
 
 Flash Signals, with Heliograph, Search Light, or 
 
 Lantern 14 
 
 Sound Signals, with Fog Whistle, Fog Horn, or 
 
 Bngle 15 
 
 The Flag . .16 
 
 Signaling with the Flag 16 
 
 The Torch 18 
 
 Signaling with the Torch 18 
 
 The Heliograph 21 
 
 Field Equipment 21 
 
 Setting up and adjusting 25 
 
 Remarks 27 
 
 Field Stations . . . 31 
 
 Messages in Cipher 38 
 
 The Compass 41 
 
 Maps 42 
 
 Military Photography 43 
 
 7 
 
8 CONTENTS. 
 
 PAGE 
 
 Transportation of Apparatus 45 
 
 Organization, Equipxment, and Command , . .49 
 Appendix i: 
 
 The Morse Telegraph Code . . . . "^. .51 
 Appendix ii: 
 
 Use of Myer Code for Telegraphing , . . .53 
 Appendix hi: 
 
 Table of Magnetic Declinations in the United States. 55 
 Index 63 
 
THE MYER SYSTEM OF 
 AEMY AND NAVY SIGNALING. 
 
 
 
 
 ALPHABET. 
 
 
 
 1. 
 
 A.... 
 
 ....22 
 
 J.... 
 
 . . . 1122 
 
 S 
 
 . 212 
 
 
 B.... 
 
 .2112 
 
 K... 
 
 ...2121 
 
 T 
 
 ....2 
 
 
 C... 
 
 ...121 
 
 L.... 
 
 ....221 
 
 U 
 
 ..112 
 
 
 D.... 
 
 ...222 
 
 M .. 
 
 ...1221 
 
 V 
 
 .1222 
 
 
 E.... 
 
 ....12 
 
 N... 
 
 11 
 
 W 
 
 .1121 
 
 
 F.... 
 
 ..2221 
 
 0... 
 
 21 
 
 X 
 
 .2122 
 
 
 G.... 
 
 ..2211 
 
 P... 
 
 ...1212 
 
 Y 
 
 ..111 
 
 
 H.... 
 
 ...122 
 
 Q • • • 
 
 ...1211 
 
 Z 
 
 .2222 
 
 
 I 
 
 1 
 
 R... 
 
 ....211 
 
 tion 
 
 .1112 
 
 
 
 
 NUMERALS. 
 
 
 
 
 
 1 
 
 ...1111 
 
 6 
 
 .2211 
 
 
 
 
 2 
 
 ...2222 
 
 7 
 
 ..1222 
 
 
 
 
 3 
 
 ...1112 
 
 8 
 
 ..2111 
 
 
 
 
 4 
 
 ...2221 
 
 9 
 
 ..1221 
 
 
 
 
 5 
 
 . . . 1122 
 
 
 
 ..2112 
 
 
 
 
 
 ABBREVIATIONS. 
 
 
 
 A- 
 
 -After 
 
 H- 
 
 -Have 
 
 T— The 
 
 W 
 
 —Word 
 
 B- 
 
 -Before 
 
 N- 
 
 -Not 
 
 U— You 
 
 Wi-With 
 
 C- 
 
 -Can 
 
 R- 
 
 -Are 
 
 Ur— Your Y- 
 
 -Yes. 
 
 
 
 
 
 9 
 
 
 
10 INSTRUCTIONS IN 
 
 CONVENTIONAL SIGNALS. 
 
 2. End of a word : 3 
 
 End of a sentence (or address) : 33 
 
 End of a message : 333 
 
 Acknowledgment, or '' I understand " : 22 22 3 
 
 Error: 12 12 3 
 
 Signature follows : sig. 3 
 
 Repeat after (word) : 121 121 3 22 3 (word) 
 
 Repeat last word : 121 121 33 
 
 Repeat last message : 121 121 121 333 
 
 Wait a moment : 1111 3 
 
 Move a little to right : 211 211 3 
 
 Move a little to left : 221 221 3 
 
 Numerals follow (or) numerals ended : XX 3 
 
 Signal faster : 2212 3 
 
 Cease signaling : 22 22 22 333 
 
 CODE CALLS. 
 
 3. I C U — International Code Use. 
 
 T D U— (Navy) Telegraph Dictionary Use. 
 
 G L U — (Navy) Geographical List Use. 
 
 G S U— (Navy) General Signal Use. 
 
 C A U— Cipher "A'^ Use.* 
 
 C B U— Cipher " B " Use.* 
 
 C C U— Cipher '' C " Use.* 
 
 N L U— Navy List Use. 
 
 V N U — Vessel's Numbers Use. 
 
 INSTRUCTIONS FOR USING THE SYSTEM. 
 
 4. The whole number opposite each letter or nu- 
 meral stands for that letter or numeral. 
 
 * For preconcerted use in or with the Navy. 
 
MILITARY SIGNALING. 
 
 11 
 
 At the end of each word, abbreviation, or conven- 
 tional signal, " 3 " is made. 
 
 Make a slight pause after each letter and also after 
 "front." 
 
 Each station should have its own signal or call let- 
 ter, as Washington, " W" ; and each signalist his per- 
 sonal signal, as Jones, " Jo." 
 
 If the call letter of the station wanted be not 
 known, signal " A " until acknowledged. 
 
 If the sender discovers that he has made an error, 
 he should make the "front" and 12 12 3 after which 
 he proceeds with the message, beginning with the word 
 in which the error occurred. 
 
 Numbers which occur in 
 the body of a message must 
 be spelled out in full. 
 
 Numerals may be used in 
 signaling between stations hav- 
 ing naval signal books, using 
 the code calls. 
 
 TO SIGNAL WITH FLAG, TORCH, 
 HAND LANTERN, OR BEAM OF 
 SEARCH LIGHT. 
 
 posi- 
 
 5. There are but one 
 tion and three motions. 
 
 The first position is with the 
 flag or other appliance held ver- 
 tically, the signalman facing 
 squarely toward the station witli 
 which it is desired to communi- 
 cate. 
 
 The first motion, or "one" 
 
 First position. 
 
12 
 
 INSTRUCTIONS IN 
 
 or " 1 " : the signal is waved to the right of the sender, 
 and will embrace an are of 90°, starting with the ver- 
 tical and returning to it, and will be made in a plane 
 
 T 
 
 exactly at right angles to the line connecting the two 
 stations. 
 
 . The second motion, or "two" or "2," is a similar 
 motion to the left of the sender. 
 
 To make the third motion, "front" or "three'' or 
 "3," the signal is waved to the ground directly in front 
 
MILITARY SIGNALING. 
 
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 r:-"--> 
 
 of the sender, and instantly re- 
 turned to the first position. 
 
 To use the torch or hand lan- 
 tern, a foot light must be used as 
 a point of reference to the mo- 
 tion. The lantern is more con- ^^ ^ 
 veniently swung out upward by 3 
 
 hand from the foot light for " 1 " 
 and " 2 " and raised and lowered vertically for " 3 ". 
 
 6. To call a station. — Signal its initial or call let- 
 ter until acknowledged. 
 
14 INSTRUCTIONS IN 
 
 To acknowledge a call. — Signal " I understand," fol- 
 lowed by the call letter of the acknowledging station. 
 
 To break or stop the signals from the sending 
 station. — Hold the flag or other appliance in the " first 
 position " until sender stops sending. 
 
 To start the sending station after breaking. — Sig- 
 nal 121 121 3 22 3 followed by the last word correctly 
 received. The sender will immediately resume his 
 message, beginning with the word indicated by the 
 receiver. If nothing has been received, signal 121 121 
 121 333. 
 
 To acknowledge receipt of a message. — Signal 22 
 22 3 followed by the personal signal of the receiver. 
 
 FLASH SIGNALS, 
 WITH HELIOGRAPH, SEARCH LIGHT, OR LANTERN. 
 
 7. Use short flash for " 1," two short flashes in 
 quick succession for " 2," and a long steady flash for 
 " 3." The elements of a letter should be slightly longer 
 than in sound signals. 
 
 To call a station. — Signal its initial or call letter 
 until acknowledged, then turn on a steady flash until 
 answered by a steady flash. Both stations will then 
 adjust, each on the other's flash. When adjustments 
 are satisfactory, the station called will cut off its flash, 
 and the calling station will proceed with the message. 
 
 To acknowledge a call. — Signal " I understand." 
 
 To break or stop the signals from the sending 
 station. — Make a rapid succession of short flashes with- 
 out pause until sender stops sending. 
 
 To start the sending station after breaking. — 
 (Same as with flag.) 
 
 Adjustment. — If sending station gets out of adjust- 
 
MILITARY SIGNALING. lo 
 
 ment, receiving* station calls for adjustment by turn- 
 ing on steady flash. Sender will answer by steady 
 flash and will adjust on receiver's flash. When ad- 
 justment is satisfactory to receiving station, it will 
 cut off its flash and sender will proceed, commencing 
 with the last word sent. 
 
 To acknoivledge receipt of a message. — (Same as 
 with flag.) 
 
 SOUND SIGNALS, 
 WITH FOG WHISTLE, FOG HORN, OR BUGLE. 
 
 8. Use one toot (about half a second)^ for " 1," two 
 toots in quick succession for ''2," and a blast (about 
 two seconds long) for '' 3." The ear and not the watch 
 is to be relied upon for the intervals. 
 
 The signal of execution for all tactical or drill 
 signals will be one long blast followed by two toots in 
 quick succession. 
 
 In the use of any other appliance, such as a bell, by 
 which a blast can not be given, three strokes in quick 
 succession will be given in place of the blast to indi- 
 cate '' 3." 
 
 When more than two vessels are in company, each 
 vessel, after making " I understand," should make her 
 call letter, that it may be certain which vessel has ac- 
 knowledged. 
 
 ORDER OF SENDING A MESSAGE. 
 
 . 9. 1 — Number of message. 
 2 — Place from, and date. 
 3— Address in full (followed by 33). 
 4 — Body of message. 
 5 — Sig 3 (signature follows). 
 6 — Signature. 
 
16 INSTRUCTIONS IN 
 
 Note. — In pronouncing the whole numbers of the Myer alpha- 
 bet, A is called "twenty-two"; B, "twenty-one twelve"; C, "one 
 twenty-one " ; D, " two twenty-two " ; E, " twelve " ; F, " twenty- 
 two twenty-one " ; G, "twenty-two eleven " ; H, "one twenty-two," 
 etc. This method is more convenient and expeditious than any 
 other. 
 
 THE FLAG. 
 
 10. Signal flags are made of muslin or other mate- 
 rial of light and close texture, are square in shape, and 
 have a smaller square in the center, comprising one 
 ninjth of the surface of the flag, of a diff'erent color 
 from the body of the flag. 
 
 Those commonly used are : The white flag, four 
 feet square, having a red block sixteen inches square 
 in its center. The red flag, four feet square, having 
 a white block sixteen inches square in its center. The 
 white flag, two feet square, hav^ing a red block eight 
 inches square in its center. The red flag, two feet 
 square, having a white block eight inches square in 
 its center. 
 
 In addition to the above, six-foot flags with centers 
 two feet square are often used, and black flags with 
 white centers are sometimes the most suitable, as in 
 case of sky backgrounds. 
 
 All flags are fitted with tapes on one edge, one foot 
 apart, for tying them to the staif. The staif is in two, 
 three, or four joints, each four feet in length. Two or 
 three joints are ordinarily used, but the longer the 
 distance the larger the flag and longer the staff. 
 
 SIGNALING WITH THE FLAG. 
 
 11. The signalman is first instructed in the use of 
 the two-foot flag, on the upper joint. He takes the 
 
MILITARY SIGNALING. , 17 
 
 position of the soldier, faces exactly toward the re- 
 ceiving" station, with the staff vertical in front of the 
 center of his body, holding it with either hand at the 
 butt, which should be at the height of the waist. 
 
 An imaginary line, fram a point between the feet 
 of the sender to the receiver, is called the line of 
 vision. 
 
 In swinging the flag, each motion to the right or 
 left should be exactly at right angles to the line of 
 vision, and each front motion should be in the line of 
 vision. To insure this, stakes may be driven in the 
 line of vision a short distance in front of the flagman 
 and at right angles to it, the same distance to the right 
 and left. The staft' should point in the direction of 
 one of these stakes at each wave. 
 
 Expert signalmen will not need the stakes for day 
 signaling, but they are indispensable for torch signal- 
 ing at night. 
 
 The instructor should explain to the recruit how to 
 keep the flag open and prevent its fouling with the 
 staff, by giving the end of the staft' a slight scoop as it 
 reaches the lowest point in its motion. 
 
 The scoop should be made against the wind. 
 
 The importance of clean, clear cut motions of the 
 flag in a plane exactly at right angles to the line of 
 vision can not be overestimated. 
 
 The staff should be kept as upright as possible, and 
 the flag kept open, as when fouled on the staft' it may 
 become quite invisible during several motions. 
 
 In a clear atmosphere the four-foot flag may be 
 read with the naked eye four or five miles ; with a 
 field glass or telescope about twice as far. 
 
 2 
 
18 INSTRUCTIONS IN 
 
 THE TORCH. 
 
 12. The Graham-Meyer army sio^nal-torch consists 
 of an asbestos flying-torch, an asbestos foot-torch, fly- 
 ing-torch can, foot-torch can, spike for foot torch, 
 clamp for attaching flying torch to staff, and funnel — 
 all packed in a cylindrical sole-leather case carried 
 by a shoulder strap. 
 
 The illuminant used is kerosene oil, which is car- 
 ried in copper canteens holding one gallon each, two 
 of which accompany each torch. 
 
 The oil canteen should have a nozzle, and an orifice 
 for filling, through which air may be admitted behind 
 the oil, while emptying, to facilitate its flow. 
 
 The flying- torch clamp is made to fit the second 
 joint of the standard three-jointed staff. The clamp 
 and spike are carried in a special pocket on the outside 
 of the case. 
 
 When packed, the torches are inverted inside their 
 respective cans, the cup which catches the drippings 
 of the torch forming a cover. 
 
 SIGNALING WITH THE TORCH. 
 
 13. Unpack the kit and half fill each of the torch 
 cans with kerosene oil. Immerse the torches for a 
 few minutes. 
 
 Screw the spike to the foot torch and plant it firmly 
 in the ground in the line of vision, about twelve feet 
 directly in front of the point where the sender is to 
 stand. 
 
 When it is impossible to use the spike the foot 
 torch may be set on top of its can, but this is to be 
 avoided, as the can soon gets hot. 
 
MILITARY SIGNALING. 
 
 19 
 
20 
 
 INSTRUCTIONS IN 
 
 Attach the clamp to the staff and screw the flying 
 torch to the clamp. Place the cans in a convenient 
 position near the signalmen. 
 
 Light the foot torch with a match, and when ready 
 to signal, light the flying torch from the foot torch. 
 
 
 Torches packed. 
 
 At the conclusion of each message the flying torch 
 is extinguished. 
 
 To extinguish the torch, plunge it in the kerosene, 
 tightly closing the can as quickly as possible. The 
 torch thus becomes saturated anew during the inter- 
 vals in signaling. 
 
 Upon removing it from the can, allow it to drain 
 for a moment. 
 
 Should either torch need resaturating during the 
 
MILITARY SIGNALING. 21 
 
 sending of a message, at the end of a word, signal 
 " Wait a moment," and resaturate. 
 
 When the foot torch needs resaturating, the flying 
 torch should be held near the ground in its place. 
 A foot light must always be kept burning while the 
 station is in operation. 
 
 Care should be taken not to tip over or spill oil on 
 the outside of the cans or on the ground, as it gets on 
 fire and makes the cans hot and difficult to handle. 
 
 The torches are light and safe, and if every part 
 but the flying torch be lost or broken, signaling may 
 be effected so long as some kerosene, a pole, and a 
 piece of wire for attaching the torch, can be obtained. 
 
 An improvised foot torch may be made by soaking 
 a small pile of leaves or grass with kerosene, or even 
 by pouring the kerosene on the ground. 
 
 An additional supply of kerosene may be carried 
 in a metal can, the same shape as a bicycle luggage 
 case, and attached to a wheel in a similar manner. 
 
 The matches carried should be wind or Vesuvius 
 matches — i. e., those so prepared as to be inextinguish- 
 able by wind or rain. 
 
 THE HELIOGRAPH. 
 
 14. The field heliograph equipment consists of — • 
 X. A sole-leather pouch, containing : 
 
 One sun mirror. ^ t i j • i i 
 
 One station mirror. \ Inclosed m a wooden box. 
 
 One screen. One sighting rod. One screw-driver. 
 Y. A smaller pouch, sliding by two loops upon the 
 
 strap of the larger, containing one mirror bar. 
 z. A skeleton case, of leather, containing two tripod 
 
 stands. 
 
22 
 
 INSTRUCTIONS IN 
 
 c. Sun mirror. 
 
 D. Station mirror. 
 
 E. Mirror supports. 
 
 F. Tangent screws for revolving mirror about 
 
 horizontal axis. 
 
 G. Mirror bar. 
 
 H. Tangent screw with ball bearings for revolv- 
 ing mirror about vertical axis. 
 
 I. Clamp screw for attaching mirror bar to 
 tripod. 
 
 K. Spring for clamping mirrors and sighting 
 rod. 
 
 L. Sighting rod with movable disk. 
 
 M. Screen. 
 
 N. Key for screen. 
 
MILITARY SIGNALING. 
 
 23 
 
24 INSTRUCTIONS IN 
 
 15. The sun mirror has an unsilvered spot at its 
 center, the station mirror a paper disk. In other re- 
 spects they are similar. The tangent screw attach- 
 ment to the frame affords the means of revolving the 
 mirror about a horizontal axis. 
 
 The support to the frame has a conical projection 
 accurately turned to fit the socket of the mirror bar 
 and grooved to receive the clamp spring. 
 
 The screen has two shutters, operated by means of 
 a key. 
 
 The base of the frame carries a female screw for at- 
 tachment to the tripod. 
 
 16. The sighting rod is fitted to the socket of the 
 mirror bar, and is clamped in the same manner as the 
 mirrors. It carries at one end a movable disk, which 
 when turned down reveals the front sight. A piece 
 of white paper should be slipped into the disk to re- 
 ceive the ''shadow spot," and a slight puncture made 
 therein, coincident with the point of the front 
 sight, as guide in adjustment. Vertical adjustment 
 of the disk is made possible by loosening the milled 
 slide. 
 
 17. The mirror bar is provided with a clamp 
 threaded to fit the screw of the tripod. The release of 
 the clamp permits movement of the bar independent 
 of the screw. At one end is attached the tangent 
 screw for revolving mirror about a vertical axis, and 
 it should be remembered that under all circumstances 
 the sun mirror is to he clamped to this end, while the 
 socket at the other extremity is designed to receive 
 the station mirror or the sighting rod. A movable 
 spring is placed under each end of the bar for clamp- 
 ing mirrors and sighting rod. 
 
 18. The tripods are similar, the screw of either 
 
MILITARY SIGNALING. 25 
 
 serving equally well for the attachment of mirror bar 
 or screen. 
 
 Both are provided with a hook for the suspension 
 of a weight, to give greater stability when required. 
 
 SETTING UP AND ADJUSTING. 
 
 19. The position of the sun is the guide for deter- 
 mining whether one or two mirrors should be used. 
 When the sun is in front of the operator — that is, in 
 front of a plane through his position, at right angles 
 to the line of vision — the sun mirror only is required. 
 With the sun in rear of this plane both mirrors should 
 be used, although a single mirror may often be worked 
 to advantage with the sun well back of the operator. 
 In the former case the rays of the sun are reflected 
 from the sun mirror direct to the distant station. In 
 the latter they are reflected from the sun mirror to the 
 station mirror, thence to the distant station. 
 
 20. With one mirror : Set the tripod firmly on flie 
 ground, attach the bar to the tripod, insert and clamp 
 in their appropriate sockets the sun mirror and the 
 sighting rod. the latter with its disk turned down. 
 Sight through the center of the mirror and turn the 
 bar and raise or lower the sighting rod until the cen- 
 ter of the mirror, point of sighting rod, and distant 
 station are accurately in line ; then clamp the bar firm- 
 ly to the tripod, being careful not to disarrange the 
 alignment. 
 
 Turn up the disk of the sighting rod. Move the 
 mirror by means of the slow-motion screws until the 
 "shadow spot" falls upon the disk of the sighting 
 rod. The flash will then be visible to the distant ob- 
 
26 INSTRUCTIONS IN 
 
 The shadow spot must he kept in the center of 
 the disk while signaling, and should he kept there 
 hy constant adjustment of the mirror. Attach the 
 screen to the tripod, and place it close to and in front 
 of the sig-hting- disk so as to intercept the flash. 
 
 21. With two mirrors : Set the tripod firmly on 
 the g-round, clamp the bar, diagonally across the line 
 of vision to the distant station, clamp the sun mirror 
 facing" the sun to the end of bar with tangent-screw 
 attachment, and the station mirror facing the distant 
 station to the other socket. 
 
 Stooping down, the head in rear of and near the 
 station mirror, turn the sun mirror by means of its 
 slow-motion screws until the whole of the station mir- 
 ror is seen reflected in the sun mirror, and the unsil- 
 vered spot and reflection of the paper disk accurately 
 cover each other. Still looking into the sun mirror, 
 turn the station mirror until the reflection of the dis- 
 tant station is brought accurately into line with, or is 
 cohered by, the unsilvered spot and the reflection of 
 the paper disk. After this the station mirror must not 
 be touched. 
 
 Now, stepping behind the sun mirror, throw upon 
 the station mirror a full flash from the sun mirror, so 
 that the shadow spot falls upon the center of the paper 
 disk. The flash will then be visible at the distant 
 station. 
 
 The shadow spot must he kept in the center of 
 the disk while signaling, and should he kept there 
 hy constant adjustment of the mirror. Attach the 
 screen to its tripod and place it so as to intercept the 
 flash from the station mirror. 
 
 22. Signaling is effected by depressing the screen 
 for periods of time required to display flashes. 
 
MILITARY SIGNALING. 27 
 
 " 1 " is represented by a momentary exposition of 
 the flash. 
 
 " 2 " by two short flashes in quick succession. 
 
 ' 3 " by a lon^ steady flash. 
 
 It is of the utmost importance that uniformity in 
 mechanical movement of the screen be cultivated, as 
 lack of rhythm in the signals of the sender entails un- 
 necessary and vexatious concentration of attention 
 upon the receiver. 
 
 The flashes should be sharp and clear cut. For a 
 " 3 " dwell somewhat upon the exposure, with a tend- 
 ency to lengthen rather than shorten the period of 
 duration. 
 
 Heliograph station, roof of warehouse. 
 
 REMARKS. 
 
 23. In setting up the instrument, spread the tripod 
 legs sufficiently to give a good base, and on yielding 
 soil press firmly into the ground, the head approxi- 
 
28 INSTRUCTIONS IN 
 
 mately level. In a hig-h wind, ballast by hanging a 
 substantial weight to the hook. 
 
 If the legs become loose at the head joints, apply 
 the screw-driver to the assembling screws. 
 
 24. See that the screen completely obscures (cuts 
 off) the flash, also that the flash passes entire when 
 the key is depressed. 
 
 The spiral spring should return the screen sharply 
 to its normal position when the key is released. If it 
 fails to respond promptly, strengthen or replace. 
 
 26. Extra care bestotved on preliminary adjust- 
 ment is repaid by increased brilliancy of flash. 
 With alignment absolutely assured, and the shadow 
 spot at the center of the disk, the axis of the cone of 
 reflected rays is coincident with the line of sight, and 
 the distant station receives the greatest possible inten- 
 sity of light. 
 
 The distant operator is necessarily the best judge 
 as to the flash received ; if, therefore, adjustment is 
 called when the shadow spot is at the center of the 
 disk, alignment is at fault. 
 
 Accuracy of alignment may be tested by looking 
 into the sun mirror, bringing the eye into line with 
 the unsilvered spot, the reflection of the disk, and re- 
 flection of the distant station. If it is found that a 
 line through the center of the unsilvered spot and re- 
 flection of the disk strikes a little to one side of the 
 reflection of the distant station, grasp the mirror bar 
 firmly, without loosening the clamp, and slightly turn 
 it, so that the reflection of the distant station will be 
 brought accurately into line. If the reflection of the 
 distant station appears slightly above or below a line 
 through the center of the unsilvered spot and reflection 
 of the disk, bring it into line by pressing the front or 
 
MILITARY SIGNALING. 29 
 
 rear tripod leg's farther into the ground, as the case 
 may require. 
 
 26. The tendency of the shadow spot to move off the 
 disk, due to the apparent motion of the sun, is com- 
 pensated for, without interrupting signals, by means 
 of the tangent screws of the sun mirror. The move- 
 ment imparted to the mirror by these screws does not 
 disturb alignment, as its center (the unsilvered spot) 
 is at the intersection of the axes of revolution. 
 
 27. The manipulation of the instrument involves 
 but slight manual labor ; the strain on the eyes, how- 
 ever, from the flash of the mirror in receiving, is 
 often considerable, but may be modified by the use of 
 stained glasses. 
 
 Ability to read signals from the heliograph may be 
 readily acquired, but may also be as readily lost if 
 practice be discontinued before proficiency is attained. 
 It should therefore be the endeavor to acquire such 
 facility, not only in sending but in receiving, that 
 habit will come to the aid even after the lapse of con- 
 siderable time. 
 
 28. Minor parts of the instrument should be dis- 
 mounted only to effect repair. All steel should be 
 preserved from rust, and tangent screws and bearings 
 from dust and grit. The mirrors should invariably be 
 wiped clean before using. 
 
 In case of accident to the sun mirror the station 
 mirror may be made available as such by removing 
 the paper disk. 
 
 29. The projection of the rays of the sun upon a 
 screen, by reflection from plane mirrors, demonstrates 
 that for short distances (varying with the size of the 
 mirrors employed) the figures of illumination are sim- 
 ilar to those of the mirrors used. Removino: the mir- 
 
30 INSTRUCTIONS IN 
 
 rors to a greater distance from the screen, it is found 
 that the shapes of the mirrors are no longer reflected, 
 but that all images are circular and of the same di- 
 ameter. 
 
 Removing the mirrors to a still greater distance, it 
 is found that the various images are circular as before 
 and of the same diameter, but that this latter diameter 
 is greater than the one previously obtained. Repeat- 
 ing the experiment at increased distances, these results 
 are confirmed, with the following conclusions : 
 
 a. That up to a certain distance the form of the 
 mirror is reflected upon the screen. 
 
 h. That this distance once exceeded, the reflected 
 images obtained from mirrors of various shapes and 
 sizes are all circular and of equal diameters at equal 
 distances. 
 
 c. That the greater the distance from the mirror to 
 the screen, the greater the diameter of the reflected 
 image. 
 
 d. That the images vary in brightness, the larger 
 mirrors producing the brighter images. 
 
 It is therefore evident that the advantage derived 
 from the use of a large mirror consists, not in any in- 
 crease in the size of the flash, but in an increase of 
 brightness — that is, capability of overcoming such ob- 
 structions as fog, smoke, haze, and consequently dis- 
 tance. 
 
 30. The light from the sun is projected upon the 
 surface of the mirror in a cone of rays, and is reflected 
 in a cone of the same dimensions. The angle within 
 which the reflection is visible is that subtended by the 
 diameter of the sun. The limit of the lateral extension 
 of the flash at any given distance may therefore be 
 definitely determined. 
 
MILITARY SIGNALING. 31 
 
 It is found that the circle of illumination has a 
 diameter which increases sixteen and one third yards 
 for every mile of distance from the mirror. 
 
 As the diameter of the flash increases directly with 
 the distance between stations, adjustment of the in- 
 strument is quite as simple and certain for great as for 
 short distances. Although the margin of flash is ample, 
 so that signals may be directed upon a station, how- 
 ever distant, with certainty, yet it is so slight relative 
 to the distance between communicating points that 
 signals are invisible to one far out of the direct line, 
 and are therefore not liable to be read by those for 
 whom not intended. 
 
 31. The range over which signaling may be effected 
 under favorable atmospheric conditions is limited only 
 by the convexity of the earth. The square mirror is 
 adopted in preference to the round, as containing about 
 one fourth more reflecting surface for practically the 
 same packing space. 
 
 Signaling at night, in the squad room, may be ef- 
 fected by the employment of artificial light. 
 
 FIELD STATIONS. 
 
 32. Each station should have its own signal or call 
 letter. A terminal station should be manned by a 
 non-commissioned olRcer and three men, and an in- 
 termediate station by an officer and six men. A cen- 
 tral station requires three men to each station with 
 which it is in communication. 
 
 CoTitinuous work requires a sufficient number of 
 men to form three reliefs. Each relief should consist 
 of the number of men stated above. The tour for each 
 relief should be four hours. 
 
32 INSTRUCTIONS IN 
 
 33. When signaling with the flag-, one man calls, 
 off the letters (not the numerals that stand for them), 
 another sends, while the third watches the distant 
 station. 
 
 In receiving, one of the men reads, one records, and 
 the other is stationed at the sending point, with flag at 
 *' front " or '' 3," to break if necessary. 
 
 When signaling with a torch, one man calls off, 
 another sends, and the third watches the distant sta- 
 tion, keeps torch cans filled, etc. In receiving, one 
 man reads, another records, and the third stands at 
 the sending point, ready to break if necessary, keeps 
 foot torch saturated and burning, etc. 
 
 When signaling with a heliograph, one man calls 
 off, one sends, and the third keeps adjustment. The 
 man sending keeps watch of the distant station. In 
 receiving, one man reads, another records, and the 
 third keeps adjustment. The man who reads stands 
 at screen to break if necessary. 
 
 If the recorder sees that a word is not intelligible 
 or if the readers are in doubt about a letter, the sender 
 immediately breaks the sending station and signals 
 121 121 3 ^"^ 3, followed by the last word correctly re- 
 ceived. 
 
 34. The officer or non-commissioned officer in 
 charge of the station is responsible for everything in 
 connection with it. He gives his entire attention to 
 the working of the station, and will compel each 
 member of the party to attend strictly to his own 
 business. He contiimally notes the correctness of the 
 adjustment of the heliograph, and tests its alignment 
 from time to time. He has charge of the apparatus 
 and equipments, and sees that all messages are cor- 
 rectly copied and transmitted, either to the communi- 
 
MILITARY SIGNALING. 33 
 
 eating station or to the person for whom they are in- 
 tended. 
 
 The person in charge of a station may never take 
 it upon himself to make any alterations in a message. 
 He must bear in mind the confidential nature of the 
 work, and will see that unauthorized persons do not 
 loiter about the station, and that no one interferes 
 with the work of the party. No talking can be al- 
 lowed while actual work is going on, beyond the neces- 
 sary calling off, and giving of orders. 
 
 An exact, copy of every message sent and received 
 must always be kept, with date and hour of receipt 
 and transmission. 
 
 Communications transmitted by signals are always 
 confidential, and will only be revealed to those of- 
 ficially entitled to receive them. 
 
 35. A strict watch upon all other stations, and upon 
 points from which calls are likely to come, must be 
 kept at all times. 
 
 Failure to promptly recognize and reply to calls, or 
 to correctly receive and transmit messages, is punish- 
 able, .in case of either officers or enlisted men, as neg- 
 lect of duty. 
 
 In case the sending station can not get an answer- 
 ing signal, but has reason to believe that its own sig- 
 nals are visible, it should send the message repeatedly. 
 
 It must be remembered that it is the duty of the 
 signal corps to transmit messages, and any excuse for 
 a failure to do so may well be received with ill grace. 
 Faithful, persistent, and, it may be, desperate efforts, 
 must be made to fulfill requirements, though in the 
 face of unlooked-for and adverse circumstances. 
 
 36. It should be remembered that accuracy is of 
 paramount importance, and rapidity in signaling 
 
34 INSTRUCTIONS IN 
 
 must always be subordinated to it. If any doubt as to 
 a character exists, the sender will be required to re- 
 peat it. 
 
 37. In field work it is imperative that the greatest 
 care be taken in selecting the station. 
 
 Stations ought not, when it can be avoided, to be 
 located exactly on an east and west line, or in the 
 line of the apparent course of the sun. It is impos- 
 sible to signal in the line of the rising or setting sun, 
 not only on account of the blinding light, but because 
 of the haze in which the landscape in the direction of 
 the sun is very liable to seem to be enveloped. 
 
 A station should not, if avoidable, be located in a 
 camp, or where the white canvas of tents is liable to 
 form the background. The manoeuvering of troops in 
 nn encampment, the passage of individuals, the smoke 
 from the kitchens, the difficulty of distinguishing at 
 night the signal torches or lights from the changing 
 lights of the encam])ment, and the curiosity of persons 
 not attached to the station, make a camp the most un- 
 suitable locality for a signal station. 
 
 The point chosen should be near the headquarters 
 of the commanding general, but outside of the camp 
 and on one side of it. If no natural height presents, a 
 platform may be built in the top of a tree, or a scaffold 
 erected from the ground. The tops of ordinary build- 
 ings are to be avoided for signal stations, as in night 
 signaling, burning oil from the torches is almost sure 
 to set the building on fire. 
 
 38. Stations should invariably be on the most ele- 
 vated ground accessible, and should never, if avoid- 
 able, be placed on low land. The undulation of the 
 atmosphere noticeable on a hot summer day is always 
 less at a distance from the earth's surface, while in the 
 
MILITARY SIGNALING. 35 
 
 cool night air the smoke and dust of the day and the 
 heavy moving mists lie close to the ground, obscuring 
 the lowlands. 
 
 Flag station, parapet of high building. 
 
 Stations on the tops of city buildings should, when 
 possible, be so located as not to be visible from the 
 street. 
 
 39. Signal officers should always be supplied with 
 the best obtainable maps of the district in which they 
 may be working. 
 
 The maps should have altitudes indicated in figures. 
 In selecting stations from a map and calculating the 
 height of intervening elevations, due allowance should 
 be made for the curvature of the earth. 
 
 The top of a lighthouse one hundred and fifty feet 
 above sea level becomes invisible from the. level of 
 the water at a distance of about twenty-five miles. 
 
 The approximate increase in height of intervening 
 elevations between two stations over the figures on 
 
36 INSTRUCTIONS IN 
 
 the map, resulting" from the curvatm^e of the earth, 
 may thus be roug-hly calculated. 
 
 Officers should enter in field books provided for 
 the purpose, sketches and minute descriptions of the 
 location of stations upon which they have worked, 
 showing upon the sketch, lines leading* to other sta- 
 tions with which communication may be held, with 
 magnetic courses to the same, and any notes or in- 
 formation which might aid in quickly locating the 
 station at some future time. 
 
 40. In signaling with the flag, the background is 
 of vital importance. 
 
 It should be of one color, and the flagman should 
 be so placed that all the motions will be outlined, 
 against it when viewed from the connnunicating sta- 
 tion. Dark colored backgrounds, such as green fields 
 or woods, are the most satisfactory. Sky backgrounds 
 are excellent, but are difficult to obtain. 
 
 The background may be a long distance, sometimes 
 many miles, behind the station. To determine what 
 the background will be, move along the line of vision 
 in front of your station, the head accurately in line 
 with the distant station, and observe your background 
 from that position. 
 
 The flag used must be of the color which contrasts 
 most greatly with the color of the background. In 
 the case of landscape backgrounds the white flag 
 should be used. With sky backgrounds use black 
 flags. With mixed backgrounds red flags. In nine 
 cases out of ten the white flag w411 be found best. 
 
 41. It is important that every motion and position 
 of the flag be visible at the receiving station. It is 
 possible that trees or bushes may hide the flag in one 
 of its motions, although they be a long way off. 
 
MILITARY SIGNALING. 37 
 
 To determine that the flag-man is so placed that 
 nothing" obstructs a view of the flag in any of its 
 motions, when viewed from the receiving station, go 
 to the points to the right, left, and front of the flag- 
 man, and, stooping down, with the face at about the 
 height of the flag at its lowest point, see if the farther 
 station be visible from there. If so, then rise, and see 
 if the farther station is visible as you rise. 
 
 The above precaution should ahvays be taken. 
 
 42. When using the torch, similar care should be 
 taken that the background does not interfere with the 
 visibility of the light. No lights or fires should be in 
 the rear of, or near, the station. At a distance of five 
 miles, a light twenty-five feet to one side of the line of 
 vision will interfere with the visibility of the torch. 
 
 For night signaling, stakes should be driven and 
 the apparatus prepared before dark. The torches will 
 work much better if saturated for some hours before 
 using. When the front motion is made with the fly- 
 ing torch its flame should appear to blend with the 
 foot torch. The signalman should stand exactly be- 
 hind the foot torch and the length of the torch staff 
 from it. 
 
 43. The same precautions, that the torch be visible 
 throughout every motion, should be taken as for the 
 flag, being even more important in night than in day 
 signaling. Particular care should be taken that the 
 foot torch is not hidden by grass or brush. To insure 
 this, lie on the ground, the face at the level of the foot 
 torch, and see if the farther station can be seen. Also, 
 with the head close to the ground, look between the 
 signalman's heels at the distant station, and see that 
 the foot torch is exactly in the line of vision. 
 
 In case of a high wind blowing from the distant 
 
38 INSTRUCTIONS IN 
 
 station, build a screen about two feet high between 
 the foot torch and the sender. The back draught will 
 prevent the light being blown out. A screen in the 
 same position will also shield the light should the wind 
 blow toward the distant station. 
 
 Screens may also be built to screen the foot torch 
 from a side wind, care being taken not to obscure the 
 flying torch in any position. 
 
 44. When signaling with the heliograph, it will 
 often be necessary, in opening communication, to find 
 the direction by compass. After the course has been 
 found the instrument should be sighted as nearly as 
 possible on the point where the distant station is sup- 
 posed to be, and the flash swept by the slow motion 
 screws slowly back and forth in a small arc, occasion- 
 ally changing it to a little higher or lower plane. 
 
 Attention may often be attracted by taking a spare 
 mirror and flashing it tow^ard the distant station. The 
 flash may be directed by selecting some near object 
 nearly in line with the distant station, as a reference 
 point. 
 
 MESSAGES I^ CIPHER. 
 
 45. In active service all messages should be trans- 
 mitted in cipher. The United States Army cipher 
 disk consists of two disks fastened concentrically to- 
 gether in such a way that they may be revolved, and 
 clamped at any point by a thumbscrew. 
 
 Around the edge of the larger disk the alphabet is 
 written from left to right ; on the smaller one, from 
 right to left. 
 
 If there be no previous agreement, "A'' on the 
 inner circle will be set opposite " A " of the outer 
 circle. 
 
i , Tt(9« 
 
 n 
 
 kY SIGNALING. 
 
 39 
 
 The letters of the message, which is written in plain 
 English, are found on the one circle, and the letters 
 opposite them on the other circle signaled. 
 
 The operator at the receiving station writes tlie 
 message down as it is sent, and afterward translates it 
 by using his own disk, which should be adjusted the 
 same as that of the sender. 
 
 46. It is usual to agree on a cipher word in ad- 
 vance. The message is divided into groups of four 
 letters each. The first group is enciphered by setting 
 the arrow on the inner disk at the first letter of the 
 cipher word on the outer circle. The second group is 
 enciphered by setting the arrow at the second letter of 
 the cipher word, and so on. When all the letters of 
 
40 INSTRUCTIONS IN 
 
 the cipher word have been used in turn, commence at 
 the first letter again. 
 
 In signaling, a front or space signal is made after 
 each group. 
 
 In enciphering or deciphering a message, it makes 
 no difference which disk the letters are found on. The 
 result is the same whether one finds a letter on the outer 
 circle and records the letter opposite it on the inner 
 circle, or finds the letter on the inner circle and records 
 the letter opposite it on the outer circle. The circles 
 may be used indifi^erently. 
 
 47. Messages sent in cipher should, to prevent 
 errors, be repeated back by the receiving station. This 
 should be done group by group — i. e., as soon as a group 
 of four letters is received, it should be repeated back 
 before the next group is sent. 
 
 Cipher dispatches to which the key is unknown 
 may often be deciphered by the rule of frequency of 
 occurrence of letters. 
 
 The order of precedence among the letters, accord- 
 ing to the frequency of their occurrence, is as follows : 
 e, a, o, i, t, d, h, n, r, s, u, y, c, f, g, 1, m, w, b, k, 
 p, j, q, X, z. ^{ — 
 
 The most frequent compounds are : th, ng, ee, 11, 
 mm, tt, dd, and nn. . 
 
 48. Important dispatches by courier should not 
 only be written in cipher, but may be written in in- 
 visible ink made as follows : 
 
 Chloride of cobalt 50 grains ; 
 
 Distilled water 1 lluid ounce ; 
 
 Glycerin 10 minims. 
 
 Dissolve the chloride of cobalt in the distilled water 
 and add the glycerin. 
 
MILITARY SIGNALING. 41 
 
 Writing executed with this ink is invisible on paper, 
 but, on warming, tlie writing turns blue. On exposure 
 to damp air it becomes invisible again. 
 
 THE COMPASS. 
 
 49. In long-range signaling wnth the heliograph 
 it will often be necessary to use the compass, espe- 
 cially when the line and stations are selected by the 
 map. In finding the course from one station to an- 
 other, by the map. it must be remembered that the 
 meridian lines run toward the true north, while the 
 compass needle points to the magnetic north. 
 
 The variation of the compass for the locality in 
 question must be known. See Appendix III for table 
 of Magnetic Declinations in the United States. 
 
 In finding a magnetic course on the map with a 
 l^rotractor, allowance must be made for the variation 
 of the needle. If the protractor readiuj^ between two 
 stations be on that side of north to which the needle 
 varies, the amount of the variation must be subtracted 
 from the protractor reading to get the magnetic course. 
 If the protractor reading of the course between the 
 stations be on the opposite side of north from that to 
 which the needle varies, then the variation must be 
 added to the reading to get the magnetic course. 
 
 60. The best compass for signal work is that called 
 a "military compass," mounted in a square wooden 
 box, about three inches on a side. It is graduated to 
 degrees, and reads from zero around to 360°, zero being 
 at the north point. 
 
 The north and south line is at right angles to the 
 side to which the cover is hinged, and the cover has a 
 sighting line cut in its under side, so that when open 
 
42 INSTRUCTIONS IN 
 
 the line is in prolongation of the north and south line 
 of the dial. 
 
 In this compass the west is on the right-hand side 
 of north, and east on the left hand, so that when the 
 needle points to the given bearing the sight line will 
 point in the desired direction. This saves calculation 
 and confusion ; but when taking a bearing with the 
 compass it must be borne in mind that the east and 
 west are reversed. 
 
 MAPS. 
 
 51. The signal corps should always be supplied 
 with the best obtainable maps of the country in which 
 they may be operating. United States topographical 
 maps, in sections, are preferable. 
 
 The margin should be trimmed off the top and 
 left-hand sides, and each section should be folded once 
 lengthwise and once crosswise, making the folded sec- 
 tion about eight by ten inches. 
 
 The sections should be numbered both inside and 
 out to correspond with the index, and packed in a sole- 
 leather case carried by a shoulder strap. The map 
 should always be carried in the field. If such maps 
 are not obtainable, those supplied should have the alti- 
 tude of dominant points, in feet, above sea level, indi- 
 cated. 
 
 52. To find the magnetic course between two points 
 on the map, in order that the direction of one from 
 the other may be found by the compass, draw a light 
 pencil line by means of a straight edge between the 
 points. Take a transparent protractor and lay it on 
 the map, curved edge to the north, with the line run- 
 ning between the point in the center of the base line 
 
MILITARY SIGNALING. 43 
 
 and ninety degrees, on a meridian line, and with the 
 point in center of the base line exactly over where the 
 pencil line crosses the meridian. 
 
 Note the number of deg'rees from north at which 
 the pencil line crosses. If the line crosses the circle 
 on that side of north to which the needle varies, sub- 
 tract the variation from the number of degrees from 
 north at which the pencil line crosses, and if it crosses 
 to the opposite side of north, add the variation to the 
 number of degrees from north at which the line 
 crosses, and the result will be the reading at which the 
 compass needle should be set in order that the sight 
 line on the cover shall be exactly in the line between 
 the two stations. 
 
 A protractor should always be carried in the map 
 case with the map. 
 
 Road books, such as are prepared in many States 
 for the use of cyclists, should be issued when practi- 
 cable, as they contain information as to grades and 
 condition of roads which may often be of much value. 
 
 MILITARY PHOTOGRAPHY. 
 
 53. The successful employment of photography in 
 military operations is of recent date, and is due to 
 modern improvements in apparatus and methods 
 which have rendered its operations practicable in the 
 I field. 
 
 U Photography is one of the most important aids for 
 tihe rapid acquirement of military information. The 
 l^ompactness of modern apparatus and the rapidity of 
 r^)hotographic processes render the reproduction of ter- 
 iene and enemies' works or positions the labor of but 
 few hours. 
 
44 INSTRUCTIONS IN 
 
 54. A military photograph possesses value from 
 the fact that it contains an accurate and graphic de- 
 scription of the object desired, and can be made in a 
 short space of time. 
 
 Artistic effect is not essential, for the photograph 
 is desired as a source of information, and the prime 
 requisite is absence of failure, for re-exposure will sel- 
 dom be possible. 
 
 65. Technical rather than artistic skill should be 
 cultivated. In reconnoitering work the camera is es- 
 pecially valuable, as the entire locality can be photo- 
 graphed in a few minutes and the finished prints can 
 be ready by the time the descriptive report is written, 
 thereby giving the commanding officer a full and de- 
 tailed source of information. 
 
 Ordinarily it will not be necessary to photograph 
 much of the landscape, but important places and ob- 
 jects only, such as bridges, ravines, defiles, forts, field 
 works, guns, magazines, buildings, ships, fords, land- 
 ing places, villages, signal stations, etc. 
 
 56. Any magazine camera with a rapid rectilineal 
 lens, which can be loaded in daylight, with films put 
 up in cartridge form on rolls of a capacity of twelve 
 to one hundred exposures, may be used. 
 
 The essential requirements are lightness, compact- 
 ness, strength, thoroughly seasoned wood, and metal 
 •parts strong and accurately made. 
 
 A camera which takes a picture five by seven inches 
 is preferable. The bellows should be made of red 
 Russia leather, since red ants will not eat this kind of 
 leather. 
 
 57. After the exposures have been made they may 
 be developed in the field in a dark room of cubical 
 form, five feet by four feet by three feet on the edges, 
 
MILITARY SIGNALING. 45 
 
 made of rubber blankets, or of one thickness of black 
 alpaca and one of turkey-red cotton sewed together, 
 one end being doubled so as to fold back like a cur- 
 tain. 
 
 The edges should be served with rope and eyes 
 worked in the corners of the top so that it can be sus- 
 pended in a common wall tent. An ordinary camp 
 lantern, with a couple of thicknesses of ruby cloth or 
 envelope paper, will serve as an illuminant for the 
 dark room. A couple of rubber trays, celluloid solu- 
 tion bottles, graduates, the necessary chemicals in cap- 
 sule or tabloid form, printing frame, and some ready- 
 sensitized paper, will prove sufficient for all the exi- 
 gencies of hasty field work. 
 
 68. Amateur photography is now so common that 
 it will be possible to find in any signal corps men with 
 some knowledge of the art. A few of these should be 
 detailed for instruction and practice in military pho- 
 tography in order that they may be prepared at any 
 time to accompany reconnoitering or inspecting offi- 
 cers. It has been very recently proved that by the use 
 of a camera suspended from kites it is possible to pho- 
 tograph an army or columns of troops at a distance of 
 five miles. For detailed instructions, see Manual of 
 Photography, War Department, Document No. 5, 
 Office of the Chief Signal Officer. 
 
 TRANSPORTATION OF APPARATUS. . 
 
 59. The most economical, rapid, and satisfactory 
 method of transporting signalmen and signal appara- 
 tus is by bicycle. 
 
 The bicycle should have pneumatic tires and a dia- 
 mond frame, with the largest possible space for lug- 
 
46 INSTRUCTIONS IN 
 
 gage case ; should be equipped with coasting brackets, 
 brake, and handle bars level with the saddle ; should 
 not be of too narrow tread, and should weigh not less 
 than twenty-three nor more than thirty pounds. All 
 bright parts should be blued like a rifle barrel, to ren- 
 der less conspicuous and to prevent rust. 
 
 Signal corps equipped with bicycles. ^ 
 
 60. It is a fundamental rule that the weight shall 
 be carried on the wheel and not on the man. The pis- 
 tol and haversack only should be carried on the per- 
 son, and it is often advisable to attach the haversack 
 to the machine. 
 
 The signal apparatus should be distributed among 
 the men in the party in such proportion as to equalize 
 the load as far as possible. A man should not be re- 
 quired to carry both heliograph case and tripods, if 
 avoidable. One man should carry the case, and anoth- 
 er the tripods. The heliograph case must always be 
 suspended over a rolled blanket in such a way that 
 
MILITARY SIGNALING. 
 
 47 
 
 it can not touch any part of the bicycle, as the jar 
 might injure the instruments. A handkerchief or a 
 piece of cloth should be stuffed in the mirror box to 
 keep the mirrors from rattling-. 
 
 61. To load the bicycle, tig-htly roll a blanket in a 
 roll about eighteen inches long and strap to front of 
 handle bar. Take mirror-bar case off the shoulder 
 sling of heliograph case and lay it on top of blanket. 
 
 Military bicycle, loaded. 
 
 With heliograph case, tripods, flag kit, blanket, shelter tent, 
 luu^t^aofe case, and canteen. 
 
 Take one turn of the shoulder sling around each end 
 of mirror-bar case, pass shoulder sling under upper 
 tube of diamond frame near the steering head, and 
 buckle tightly enough so that the case hangs sus- 
 
48 INSTRUCTIONS IN 
 
 pended in front of the blanket roll, not touching bi- 
 cycle. 
 
 Pass a strap around case and steering head, to keep 
 case from flying up and becoming displaced. Strap 
 flags in flag case, made for the purpose, tightly to right- 
 hand side of upper bar of frame. Strap heliograph 
 tripods in skeleton case tightly to frame on top of flag 
 case. Attach canteen under back of saddle, and tie in 
 bottom to frame so as to prevent rattling. 
 
 The luggage case, which serves as a knapsack, 
 should always be kept in the bicycle. When shelter 
 tents are carried, a jointed pole is rolled in center of 
 the blanket roll and half a tent rolled around blanket. 
 Pegs should be packed in luggage case. 
 
 The torch kit, or oil canteen, is packed by suspend- 
 ing over blanket roll in place of heliograph case. 
 Hand axes are carried, with a leather case protecting 
 the blade, and attached to bicycle in any convenient 
 place. Field glasses and telescopes may be carried 
 either on the person or the machine. Ponchos should 
 be rolled in a tight roll and strapped on top of upper 
 bar of frame so as to be easily accessible. 
 
 Every man should have a cyclometer, tool bag, 
 and tire repair outfit, and every party a camera. 
 
 62. It has been found that the average rate of 
 march of cyclists with full equipment is six miles per 
 hour. A halt of ten minutes should be made half an 
 hour after starting, and a halt of ten minutes every 
 hour thereafter. The men should at the completion of 
 the march be in condition for signaling or for further 
 and hard riding if necessary. 
 
 63. Signalmen should be armed with the revolver 
 only, worn on a web thimble cartridge belt, behind 
 the right hip. 
 
MILITARY SIGNALING. 49 
 
 Campaign hats should be worn in the field, a blue 
 or gray flannel shirt, blouse with pockets in the breast 
 for pencils and paper, re-enforced trousers, cavalry 
 canvas leggings, and stout shoes. 
 
 The overcoat should not be taken unless it be cold 
 enough to wear it. In warmer weather the detachable 
 cape may be taken in its place. 
 
 ORGANIZATIOIS', EQUIPMENT, AND COMMAND. 
 
 64. The chief signal officer of an army in the field 
 commands the signal corps serving therein. Orders 
 affecting them will be transmitted through him, and he 
 will be responsible that they are fully instructed, ade- 
 quately supplied, and that they properly perform their 
 duties. He will keep himself informed of the position 
 of the army and of the enemy, and under the instruc- 
 tions of the general commanding will establish his sta- 
 tions to the greatest advantage. (Army Regulations.) 
 
 Signal officers in the field will report to their im- 
 mediate commanders and to the chief signal officer, 
 for the information of the general commanding, all 
 movements of the enemy and other facts of interest to 
 the service coming within their knowledge. (Army 
 Regulations.) 
 
 65. A signal corps should be attached to each bri- 
 gade under the command of the brigade signal officer, 
 who should be a member of the staff of the brigade 
 commander. The corps should be composed of intel- 
 ligent men enlisted especially for the service, and 
 shouJd number one officer and nine men to each regi- 
 ment in the brigade, with an assistant surgeon, a first 
 sergeant, a quartermaster sergeant, and a commissary 
 sergeant in addition. 
 
 4 
 
50 INSTRUCTIONS IN MILITARY SIGNALING. 
 
 66. The unit of one officer and nine men consti- 
 tutes a '' section." Each section should consist of one 
 first lieutenant, one sergeant, two corporals, and six 
 privates. A signal corps for a brigade of four regi- 
 ments would consist of four first lieutenants, one as- 
 sistant surgeon (first lieutenant), one first sergeant, 
 one quartermaster sergea];it, one commissary sergeant, 
 four sergeants, eight corporals, and twenty-four privates 
 — total, forty -four — all under the command of the bri- 
 gade signal officer (of grade of major or captain). 
 
 If the regiments composing the brigade are sta- 
 tioned in different places, a section of the signal corps 
 may be located with each regiment. 
 
 Signalmen should be mounted on bicycles, which 
 may be purchased or hired, as may be most expedient. 
 
 67. The visual signal equipment for a corps of the 
 above strength should consist of not less than — 
 
 . 8 heliographs. 
 
 32 fiag kits, each containing two flags with one 
 staff. 
 
 8 Graham-Meyer torch kits. 
 
 8 telescopes. 
 
 8 field glasses. 
 
 No rules can be laid down for electric equipment. 
 When the Army shall have adopted a standard appa- 
 ratus for telegraphing and telephoning, instructions 
 for its use will be prepared. 
 

 APPENDIX I. 
 
 The Morse Telegraph Code. 
 
 ALPHABET. 
 
 A-— F K P U 
 
 B O L Q V. 
 
 C -- - H M E- -- W 
 
 jy I -- N— - S --- X 
 
 E - J O - - T — Y 
 
 Z--- - &- --- 
 
 NUMERALS. 
 
 1 3 5 7 9_ 
 
 2-- 4 6 8 0- 
 
 PUNCTUATION. 
 
 Corama, Exclamation, 
 
 Semicolon, Si Parenthesis, Pn 
 
 Colon, Ko Brackets, Bx 
 
 Period, Dollar mark, Sx 
 
 Interrogation, Dash, Dx 
 
 Quotation, Qn Hyphen, Hx 
 
 Paragraph, Underline, Ux 
 
 51 
 
52 APPENDIX I. 
 
 SIGNALS. 
 
 1. Wait a moment. 
 
 4. Start me. 
 
 5. Have you anything for me ? 
 
 7. Are you ready ? 
 
 8. Busy on other wires (or stations). 
 
 9. Train order (or important military message)— 
 
 give way. 
 13. Do you understand ? 
 18. What is the matter ? 
 27. Adjust your magnet. 
 30. Circuit closed (or close station). 
 44. Answer quick. 
 73. Accept compliments. 
 92. Deliver (ed). 
 134. Who is at the key ? 
 
 ABBREVIATIONS. 
 
 Ahr-^Another. G R — Government rate. 
 
 Ans — Answer. N M — No more. 
 
 Ck — Check. O B — Official business. 
 
 Col— Collect. O K— All right. 
 
 D H — Dead head. Opr — Operator. 
 
 G A— Go ahead. Pd— Paid. 
 
 G E~Good evening. Qk — Quick. 
 
 G M — Good morning. Sig — Signature. 
 
 G N— Good night. 
 
APPENDIX 11. 
 
 The Myer code may be used for telegraphing" by 
 men not familiar with the Morse telegraph code. One 
 tick is made for "1," two ticks in quick succession 
 for "2," and three ticks in quick succession for "3." 
 Pauses between the elements of a letter should be dis- 
 tinct, but not too long. 
 
 Dwell slightly upon the pause between letters. 
 
 A. 
 B. 
 C. 
 D. 
 E. 
 F. 
 G. 
 H. 
 L. 
 J. 
 K. 
 L. 
 M. 
 N. 
 O. 
 
 THE MYER CODE FOR TELEGRAPHING. 
 
 22 
 
 2112 
 
 121 
 
 222 
 
 12 
 
 .2221 
 .2211 
 ..122 
 ....1 
 .1122 
 .2121 
 .221 
 .1221 
 ...11 
 ...21 
 
 53 
 
APPENDIX II. 
 P... 1212 
 
 Q 1211 
 
 E 211 
 
 S 212 
 
 T 2 
 
 U 112 
 
 V 1222 
 
 W ..1121 
 
 X 2122 
 
 Y Ill 
 
 Z 2222 
 
 NUMERALS. 
 
 1 nil 
 
 2 2222 
 
 3 1112 
 
 4 2221 
 
 5 1122 
 
 6 2211 
 
 7 1222 
 
 8 2111 
 
 9 1221 
 
 2112 
 
APPENDIX III. 
 
 Table of the Magnetic BecUnatioyi at Various Points 
 in the United States— for the Epoch 1900, 
 
 The magnetic declination (or variation of the com- 
 pass, as it was formerly called by surveyors and still is 
 by navigators) at any place, is the angle contained be- 
 tween two vertical planes, one being the astronomical 
 or true meridian, and the other the plane in which 
 the horizontal axis of a freely suspended magnet lies 
 at the time. 
 
 The declination is called ''West" when the north 
 end of a magnet points to the west of true north, and 
 " East " when the north end of the magnet points to 
 the east of true north. 
 
 The agonic line or zero curve of the Western Hemi- 
 sphere, a line at all points upon which the magnet 
 points to the true north, crosses the United States 
 (1890) ,\n. a generally southerly direction ; entering 
 at the junction of Lake Michigan and Lake Huron, 
 passing through the center of the State of Michigan, 
 touching the western extremity of Lake Erie, souther- 
 ly through the State of Ohio, and following the gen- 
 eral direction of the boundary line between Kentucky 
 and West Virginia, it curves slightly to the eastward, 
 55 
 
56 APPENDIX III. 
 
 and then, following the direction of the Great Pedee 
 River, passes just to the eastward of Charleston, S. C. 
 
 At points east of the agonic line the declination is 
 west. At points west of the agonic line the .declina- 
 tion is east. 
 
 At present there is generally throughout the United 
 States an annual westward increase of declination, 
 varying from 0' to 5', which has been considered in 
 computing the declination as of the year 1900. 
 
 The declinations given are to the nearest degree, 
 which is sufficiently precise for ordinary use by the 
 Signal Corps. 
 
 The values given may be used without sensible in- 
 accuracy for four or five years before and after 1900. 
 
 LOCALITY. DECLINATION. 
 
 Alabama, Central part 3° E. 
 
 Western part 4° E. 
 
 Arkansas, Eastern part 5° E. 
 
 Central part. 6° E. 
 
 Western part 7° E. 
 
 Arizona, Southeastern part 13° E. 
 
 Central part 14° E. 
 
 Northwestern part 15° E. 
 
 California, Los Angeles 14° E. 
 
 Tulare Lake 15° E. 
 
 Santa Cruz 16° E. 
 
 Sacramento 17° E. 
 
 Northwestern part 18° E. 
 
 Colorado, Southeastern part 13° E. 
 
 Central part 14° E. 
 
 Northwestern part 15° E. 
 
 Connecticut, New London 11° W. 
 
 Stamford 10° W. 
 
APPENDIX III. 57 
 
 LOCALITY. DECLINATION. 
 
 Delaware 6° W. 
 
 District of Columbia 5° W. 
 
 Florida, Eastern coast 1° E. 
 
 Western coast 2** E. 
 
 Pensacola 4° E. 
 
 Georgia, Eastern part 1° E. 
 
 Central and western parts 2° E. 
 
 Idaho, Southeastern part 18° E. 
 
 Central part 19° E. 
 
 Bald Mountain 20° E. 
 
 Extreme northwest 22° E. 
 
 Illinois, Eastern part 3° E. 
 
 Central part 4° E. 
 
 Western part 5° E. 
 
 Indian Territory 9° E. 
 
 Indiana, Eastern part 1° E. 
 
 Central part 2° E. 
 
 Western part 3° E. 
 
 Iowa, Eastern part 6° E. 
 
 Des Moines 7° E. 
 
 Audubon 8° E. 
 
 Western part 9° E. 
 
 Kansas, Kansas City 8° E. 
 
 Manhattan 9° E. 
 
 Larned 10° E. 
 
 Western part 11° E. 
 
 Kentucky, Eastern extremity No variation. 
 
 Central part 2° E. 
 
 Western part 4° E. 
 
 Louisiana, Eastern part 5° E. 
 
 Western part 6° E. • 
 
 Maine, Saco 14° W. 
 
 Portland 15° W. 
 
 5 
 
58 APPENDIX III. 
 
 LOCALITY. DECLINATION. 
 
 Bangor 17° W. 
 
 Northern part 20° W. 
 
 Maryland, Baltimore 5° W. 
 
 Cumberland 4° W. 
 
 Massachusetts, Gloucester 13"* W. 
 
 Boston 12° W. 
 
 Central part 11° W. 
 
 Michigan, Detroit 2° W. 
 
 Central part No variation. 
 
 Western part 1° E. 
 
 Minnesota, Eastern part. 8° E. 
 
 Western part 9° E. 
 
 Mississippi, Eastern part •. 4° E. 
 
 Western part ...".. 5° E. 
 
 Missouri, St. Louis 5° E. 
 
 Eolla 6° E. 
 
 Sedalia 7° E. 
 
 Montana, Southeastern part 17° E. 
 
 Yellowstone County 18° E. 
 
 Virginia City 19° E. 
 
 Missoula 20° E. 
 
 Nebraska, Lincoln 10° E. 
 
 Grand Island 11° E. 
 
 Ogallala 12° E. 
 
 Nevada, Southern part 16° E. 
 
 Central part 17° E. 
 
 Northern part 18° E. 
 
 New Hampshire, Manchester 13° W. 
 
 Lake Winnepesaukee 14° W. 
 
 Northern part 16° W. 
 
 New Jersey, Southern part 7° W. 
 
 Central part 8° W. 
 
 Northern part 9° W; 
 
APPENDIX III. 59 
 
 LOCALITY. DECLINATION. 
 
 New Mexico, Southeastern part 12° E. 
 
 Central part 13° E. 
 
 Northwestern part 14° E. 
 
 New York, BuJffalo 6° W. 
 
 Rochester 8° W. 
 
 Oswego 9° W. 
 
 New York city 9° W. 
 
 Utica 10° W. 
 
 Albany 11° W. 
 
 Adirondacks 12° W. 
 
 Plattsburg 14° W. 
 
 North Carolina, Cape Hatteras 5° W. 
 
 New Berne 3° W. 
 
 Raleigh 2° W. 
 
 Great Pedee River No variation. 
 
 Asheville 1° E. 
 
 North Dakota, Eastern part 12° E. 
 
 Central part 15° E. 
 
 Western part 17° E. 
 
 Ohio, Eastern part 2° W. 
 
 Central part No variation. 
 
 Western part 1° E. 
 
 Oklahoma 10° E. 
 
 Oregon, Southern part 18° E. 
 
 Central part 19° E. 
 
 Northern part 20° E. 
 
 Pennsylvania, Wilkesbarre 8° W. 
 
 Williamsport 7° W. 
 
 Philadelphia 6° W. 
 
 Johnstown 5° W. 
 
 Pittsburg 4° W. 
 
 Rhode Island 12° W. 
 
 South Carolina, Eastern part No variation. 
 
60 APPENDIX III. 
 
 LOCALITY. DECLINATION. 
 
 Central part 1° E. 
 
 Western part 2° E. 
 
 South Dakota, Eastern part 11° E. 
 
 Central part 12° E. 
 
 Western part 14° E. 
 
 Tennessee, Eastern extremity. ..... No variation. 
 
 Central part 2° E. 
 
 Western part 4° E. 
 
 Texas, Corpus Cliristi 8° E. 
 
 Dallas 9° E. 
 
 Sherwood 10^ E. 
 
 Midland 11° E. 
 
 Utah, Southern part 15° E. 
 
 Central part 16° E. 
 
 Black Mountains 18° E. 
 
 Salt Lake 16° E. 
 
 Vermont, Southern part 13° W. 
 
 Central part 14° W. 
 
 Northern part 15° W. 
 
 Virg-inia, Richmond , . . . 4° W. 
 
 Liberty .^° W. 
 
 Marion No variation. 
 
 Washington (State), Southern part 21° E. 
 
 Central part 22° E. 
 
 Northern part. 23° E. 
 
 West Virginia, Eastern part 3° W. 
 
 Central part 2° W. 
 
 Western extremity No variation. 
 
 Wisconsin, Milwaukee. 3° E. 
 
 Fond du Lac 4° E. 
 
 Eau Claire 6° E. 
 
 Wyoming, Fort Laramie 15° E. 
 
 Sweet Water Mountains 16° E. 
 
APPENDIX III. 61 
 
 LOCALITY. DECLINATION. 
 
 Shoshone Reservation 17° E. 
 
 Yellowstone National Park 18° E. 
 
 For maps and complete data as to magnetic decli- 
 nation in the United States, see Appendix No. 7, 1888, 
 and Appendix No. 11, 1889, to the Reports of the United 
 States Geodetic and Coast Survey. 
 
INDEX. 
 
 References are to Paragraphs, 
 
 Abbreviations. 1. 
 
 Adjustment of Heliograph, 19, 20, 
 
 21, 25, 26. 
 Agonic Line, Appendix III. 
 Alignment of Heliograph, 19, 20, 
 
 21, 25, 26. 
 Alphabet, 1. 
 Apparatus, Transportation of, 59- 
 
 63. 
 Axe, where carried, 61. 
 
 Backgrounds, 40, 41, 42. 
 
 Bicycles, 59-63, 66. 
 
 Blanket under Heliograph, 60, 61. 
 
 Camera, 56, 
 Canteen, 61. 
 Cipher Disk, 45. 
 Cipher Messages, 45. 46, 47. 
 Circle of Illumination. 30. 
 Codes, 1, Appendices I and II. 
 Code Calls, 3. 
 Compass, 49, 50. 
 
 Compass, Variation of, 49, 52, Ap- 
 pendix III. 
 Conventional Signals, 2. 
 Cyclometer, 61. 
 
 Deciphering Messages, 47.' 
 Declination, Magnetic, Appendix 
 
 Description, of Bicycle, 59. 
 of Camera, 56. 
 
 63 
 
 Description, of Compass, 50. 
 
 of Dark Room, 57. 
 
 of Field Map, 51. 
 
 of Flag, 10. 
 
 of Heliograph. 14. 
 
 of Loaded Bicycle, 61. 
 
 of Torch, 12. 
 
 of Uniform, 63. 
 Disks, Cipher, 45. 
 Distances, Flag, 11. 
 
 Heliograph, 31. 
 Duties, Men on Stations, 33-36. 
 
 Enciphering Messages, 46. 
 Equipment, Visual Signal, 67. 
 
 Field Stations, 32-44. 
 
 Duties of Chief of, 34, 35. 
 Field Books, 39. 
 Fires, 42. 
 Flag, The, 10. 
 Flash Signals, with Heliograph 
 
 Search Light or Lantern, 7, 
 
 22. 
 Flying Torch, The, 12, 13, 42. 
 Foot Torch, The, 12, 13, 42. 
 Front Motion, 5, 11, 42. 
 
 Haversack. 60. 
 Heliograph, 14. 
 
 Adjustment of, 19, 20, 21, 25, 26. 
 
 Alignment of, 19, 20. 21, 25, 26. 
 
 Transportation of, 59-61. 
 
64 
 
 INDEX. 
 
 Information, to be reported, 64. 
 Instructions for using Myer Sys- 
 tem, 4. 
 Invisible Ink, 48. 
 
 Lanterns, Signaling with, 5. 
 Line of Visiofi, 11, 13, 42, 43. 
 Luggage Case, 59. 
 
 Magnetic Declination, 49, 52, Ap; 
 pendix III. 
 
 Courses, to find, 49, 52. 
 Maps, 39, 51, 52. 
 Matches, 13. 
 Messages, Order of, 9. 
 
 by Messengers, 48. 
 Military Photography, 53-58. 
 Morse Code, Appendix I. 
 Myer Code for Telegraphing, Ap- 
 pendix II. 
 Myei» System of Signaling, 1-8. 
 
 Night Signaling, 37, 42, 43. 
 Numerals, 1. 
 
 Order of Message, 9. 
 Organization, 04-66. 
 
 Position of Men in Signaling, 33, 
 
 of Stations, 37, 38. 
 Precision, 36. 
 
 Pronouncing Myer Alphabet, 9. 
 Photography, Military, 53-58. 
 
 Recording Signals, 33. 
 Recruits, Instruction of, 11. 
 
 Rhythm of Heliograph, 22. 
 Road Book, 52. 
 
 Scoop, against Wind, 11. 
 
 Signal Codes, 1, Appendices I and 
 
 II. 
 Signal Corps, Organization of, 65, 
 
 66. 
 Signaling, with Flag, Torch, or 
 
 Hand Lantern, 5, 33, 40, 41, 
 
 42, 43. 
 with Heliograph, 22, 44. 
 Size of Flags, 10. 
 Sound Signals with Fog Whistle, 
 
 Fog Horn, or Bugle, 8. 
 Speed, 36. 
 Staff, 10. 
 Stakes, 11. 
 Stations, where to be located, 
 
 37. 
 where not to be located, 37. 
 
 Table of Magnetic Declination, 
 
 Appendix III. 
 Torch, Description of, 12. 
 
 Signaling with, 13. 
 Transportation of Apparatus, 59- 
 
 Variation of the Compass, 49, 52, 
 
 Appendix III. 
 Vertical Motions, 5. 
 Vision, Line of, 11, 13, 42, 43. 
 
 Zero Circle, Appendix III. 
 
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