Signalling with a Flash Light: Use a short flash for the dot and a long steady flash for the dash. Pause the length of three dots between letters, and the length of five dots between words. A still longer pause marks the end of a sentence. Signalling by Whistle: Use a short blast for the dot, and a long steady blast for the dash. Indicate the end of a letter, a word, and a sentence by the same pauses as explained in Flash Light Signalling. Signalling with a Lantern: The motions used in signalling with a lantern are somewhat like those of the wig wag flag. For Position hold the lantern directly in front of the body; for the dot swing it to the right and back to Position; for the dash swing it to the left and back to Position; and for Interval move it down and up in a vertical line directly in front. A stationary light should be placed on the ground before the feet as a point of reference for the various motions. B. SEMAPHORE SIGNALLING SEMAPHORE CODE The semaphore is a machine with two arms which may be moved into various positions to make letters. The semaphore code shown in the accompanying picture may also be employed by a person using two flags. It is the quickest method of flag signalling but is available for comparatively short distances, seldom over a mile, unless extra large flags are employed or there is some extraordinary condition of background or atmosphere. The semaphore code is not adapted to as many uses as is the general service code, but for quick signalling over comparatively short distances, it is preferable in every way. The regulation flag is 18 inches square, either divided diagonally into two triangles of white and red, or square of white with small square of red in the center, or red with small square of white. These flags are fastened on poles 24 inches long and 1/2 inch in diameter. The flags must be carefully held so that the sticks make, as it were, a continuation of the arm bone; a bent wrist will cause the flags to make an entirely different angle, and consequently a different letter from the one intended. Swing the arms smoothly and without hesitation from one letter to another. Hold each letter long enough to make it clear to the person receiving it. Every word begins and ends with "intervals," the hands crossed downward in front of the body, arms nearly straight, right hand always over the left. Indicate the end of a sentence by one "chip-chop" made by holding both flags to the right, horizontally, and moving them up and down several times; not altogether, but one flag going down as the other comes up, making the "chopping" motion. [Illustration: CODE FOR SEMAPHORE SIGNALLING] Note: The extended arm should always make a straight line with the flag staff.