De-gassing the Trenches (1918)

METHOD OF USING CANVAS TRENCH FANS

86. (a) CLEARING TRENCHES.–The fan blade is placed on the ground with the brace side downwards, the man using it being in a slightly crouching position with the left foot advanced, the right hand grasping the handle at the neck and the left hand near the butt end. The fan is brought up quickly over the right shoulder, and then smartly flicked to the ground. This drives a current of air along the earth and, on the top strokes, throws the gas out of the trench. The part of the fan blade nearest the handle should touch the ground first, and this can be accomplished in all cases by ending the stroke with the whole length of the handle as close to the ground as possible.

87. In working a traverse…, etc, the fan should be flapped round the corner with the hinge on the corner and the lower edge of the fan as near the bottom of the trench as can be managed. The brace side of the fan is to outward, and at the end of the stroke the whole length of the handle should be close up to the side of the trench.

88. If several fans are available, men should work in a single file and with “out-of-step” strokes–i.e., one fan should be up while the next is down. (Fig. 25.)

Source and image: Gas Warfare, Part II: Methods of Defense Against Gas Attacks, Army War College, January 1918, p. 34 and fig. 25