Trench fan

For ventilation of the dugout, there was the special antigas fan known as the Canvas Trench Fan. A 1918 War College gas warfare manual dedicated seven pages to the use of the fan, although all the fan really did was disperse the gas (Figure 2-13). Still, over 25,000 trench fans were sent to the front.26 33... 

Fig. 2-13. Procedures for using the trench fan to remove chemical agents from trenches. The fan was a failure. Reprinted from Army War College. Methods of Defense Against Gas Attacks. Vol 2. In Gas Warfare. Washington, DC War Department 1918 Figure 25.

Example Mid-Atlantic Ridge. North American Atlantic and Gulf Coast Mesozoic and Cenozoic. Aleutian trench. Siwalik scries of India, Bengal submarine fan. Triassic of Eastern North America. Michigan and Eastern interior basins of North America. 

The continental slope is the "relatively steep (usually 3-6°) portion of the seafloor which lies at the seaward border of the continental shelf" (Heezen et al., 1959) in water depths ranging from 100-200 m to 1,400-3,200 m, and locally to much greater depths (Bouma, 1979). This area is located just above the transition between continental and oceanic crust. The continental slopes are narrow (20-100 km), covering an area approximately 2.87 X 10E6 km, 5.6% of the Earth s surface (Drake and Burke, 1974). About half of the world s continental slopes terminate in deep-water trenches or shallower depressions, the rest gradually merging with slopes of 1 100 to 1 700 into continental rises and their deep-sea fans (Curray, 1966). 

Marshall, N.R 1978. A large storm-induced sediment slumps reopens an unknown Scripps submarine canyon tributary. In Sedimentation in Submarine Canyons, Fans, and Trenches, Stanley, D.J., and Kelling, G., eds., Dowden, Hutchinson Ross, Stroudsburg, PA, p>p. 73-84. 

Bachman, R.T., and Hamilton, E.L. 1982. Sediment sound velocity from sonobuoys Sunda Trench and forearc basins, Nicobar and Central Bengal fans, and Andaman Sea Basin. Journal of Geophysical Research, B86(ll) 9341-9346. 

AYRTON FAN. Initiation of chemical warfare in April 1915 brought with it many suggestions for means of combating its effects. British physicist Hertha Marks Ayrton (1854-1923) made one such suggestion, which came to be dubbed the Ayrton fan. It was a handheld, broom-like device made of wood and canvas. Soldiers were issued these fans with instructions to use them to sweep away the poisonous gases that would otherwise drift into their trenches. The Ayrton fans proved a failure, as winds would force the vapors back into the trenches, and using them to sweep proved nearly impossible to do while under attack. Ayrton s prominence in British science, however, forced the govermnent to adopt them, and at least 25,000 were produced and issued, primarily to British Expeditionary Force personnel. Ayrton was the first woman to read a paper before the British... 

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