Listening for sounds from underground, Western Front, First World War, c1916, (c1920). 'Guarding against Underground Attack: British listening post on duty in the open...Note the position of the bayonet for the transmission of sound to the ear of the man on the left'. From "The Great World War: A History", Volume VI, edited by Frank A Mumby. [The Gresham Publishing Company Ltd, London, c1920]