War Department,
Office of the Chief of Staff,
Washington, April 20, 1910.

The following Manual of Visual Signaling, prepared in the Office of the Chief Signal Officer, is approved and herewith published for the information and guidance of the Regular Army and the Organized Militia of the United States, and supersedes all other pamphlets or similar instructions heretofore issued upon the subject. Officers and men of the Signal Corps will thoroughly familiarize themselves with the instructions and suggestions contained herein.

By order of the Secretary of War.

Tasker H. Bliss,
Brig. General, General Staff,
Acting Chief of Staff.

TABLE OF CONTENTS.

Page.
Chapter I.—Introduction[9]
Chapter II.—Visual signaling equipment.
The wand[11]
The flag kit:
The 2-foot flag kit[12]
The 4-foot flag kit[12]
Care of flag material[13]
Powers and limitations of flag signaling[13]
The heliograph:
Historical[14]
Description[14]
Assembling[17]
Adjustment[20]
Operation[21]
Care of apparatus[22]
Powers and limitations of the heliograph[22]
The signal lantern:
Acetylene[23]
Calcium carbide[23]
Method of gas generation[24]
Description[25]
Operation and care[30]
Powers and limitations of the signal lantern[35]
Rockets and shells:
Description[35]
Operation[38]
Employment[40]
The semaphore: Description[40]
The searchlight: Methods of employment[41]
The Coston signals[41]
Very's night signals[42]
The Ardois system of signaling[42]
Sound signals[44]
Improvised signal methods[44]

Chapter III.—Alphabets or systems of signals.
Signal alphabets:
American Morse[45]
Continental Morse[45]
Army and navy[45]
Abbreviations[46]
Code calls[47]
Execution of signal alphabets[47]
The army and navy alphabet[47]
The Morse alphabets[49]
International code of signals:
Description[51]
Two-arm semaphore[51]
The Ardois system[52]
Coston signals[54]
Very's night signals[54]
Rocket signaling[55]
Two-arm semaphore alphabet, U. S. Navy[57]
Summary of signals, army and navy alphabet[60]

Chapter IV.—The field message.
Definition[64]
The blank form[64]
Writing the message[66]
Instructions to operators:
Use of message blank[66]
Duties of sending operators[66]
Order of transmission[66]
Duties of receiving operators[67]
Communications confidential[67]
Checking the message[67]

Chapter V.—The signal station.
Location of stations:
General considerations[68]
Backgrounds[70]
Azimuth of stations[71]
Altitude[71]
Determination of background color[72]
Choice of apparatus[73]
Miscellaneous considerations[73]
Intervisibility table[74]
Finding a station[75]
Operation of stations:
Personnel[76]
Calls and personal signals[78]
Opening communication[79]
Commencing the message[80]
Sending and receiving[80]
Breaking[80]
Discontinuance of transmission[81]
Acknowledgment of receipt[81]
Station records[81]
Formation of signals[82]
Repeating the message[83]
Signal practice[83]

Chapter VI.—Codes and ciphers.
Codes in use[84]
Employment of codes[84]
Cipher code[85]
The War Department Code[86]
Cipher code in field work[87]
Field ciphers:
Description and use[87]
Forms of field cipher[88]
Inversions[88]
Concealment of terminations[88]
Cipher apparatus: The cipher disk[89]
The mathematical cipher[93]
The route cipher[94]
Cipher detection: Employment of cipher disk[96]

Chapter VII.—Field glasses and telescopes.
Reflection[98]
Refraction[98]
Lenses[98]
Focus[99]
Optical center[99]
Image[99]
Conjugate foci[99]
Law of foci[100]
Formation of image[101]
Spherical aberration[102]
Chromatic aberration[102]
Telescopes[104]
Galilean field glasses and telescopes[106]
Porro prism field glasses and telescopes[106]
Field glasses[108]
Properties of telescopes and field glasses[109]
Power[109]
Light[111]
Field[114]
Definition[115]
Field glasses and telescopes issued by the Signal Corps[119]
Type A[121]
Type B[124]
Type C[125]
Type D[125]
Field-glass specifications[126]