CONCAVE DECAY

The sound mirrors at Dungeness are the most tangible echoes of a technological narrative that begins in the trenches of the World War I. As sedulously traced by Richard N. Scarth in his book Echoes From the Sky: A Story of Acoustic Defence, the short history of the acoustic warning system starts with the efforts of the British and French armies to plot the positions of Germans guns.2 The techniques of “sound ranging” gave rise to two innovations later essential to the development of the massive sound mirrors. First, the use of “listening wells”: deep shafts which would reduce or eliminate all surface noise, allowing a listener situated at the bottom of a shaft to focus on the desired sound. Second, the development in 1916, by William Sansome Tucker, of the hot-wire microphone, a device which could be tuned to register the frequency of the gun, or later aircraft, under surveillance. Tucker was to spend the next two decades perfecting the means of identifying and locating the low-frequency sounds of aircraft and ships. In the primitive earthworks of World War I, he saw the possibility of a more technically precise and (to the eyes, at least, of a contemporary observer of the mirrors’ melancholy presences) more aesthetically astonishing technology. Tucker practiced an art of the curve: “When a solid on which a wave impinges does not exceed about one quarter of a wave-length in diameter, the wave passes round it with little interruption. When the diameter of the barrier exceeds one wave-length, appreciable reflection should occur, and therefore a certain amount of concentration should be obtained by making the surface concave.” After the war, Tucker's concavities appear in a variety of forms: as parabolic bowls with stethoscopes or microphones attached, and “mirrors” carved into cliff faces and lined with concrete.

By the mid-1930s, a vast and varied network of listening devices had been envisaged, enclosing the Thames Estuary and the south-east coast in what Paul Virilio (writing of the German defenses which would later loom along the other side of the English Channel) has called “a carpet of trajectories.” The remnants of this doomed project, the architectural remains of a technology gradually overcome in the late 1930s by experiments with radar and a generalized eruption of the acoustic realm, are still to be seen at certain points along the coast. These long-decaying but still startlingly sculptural structures are monuments to both past and future, their eerie archaeology also a reminder of the whole panoply of technologies of the immaterial that have proliferated in the military sphere, the space of war now dominated by the grotesque intersection of implacable abstraction and fragile flesh.


cabinetmagazine
Issue 12 Fall/Winter 2003/04 Listening for the Enemy
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Brian Dillon