by Dr William Sansome Tucker, had given Britain the methodology to use interconnected stations to pinpoint the position of an enemy in the sky. The system they developed for linking the stations and plotting aircraft movements was given to the early radar team and contributed to their success in World War II; although the British radar was less sophisticated than the German system, the British system was used more successfully. Modern uses Parabolic acoustic mirrors called "whisper dishes" are used as participatory exhibits in science museums to demonstrate focusing of sound. Examples are located at Bristol's We The Curious, Ontario Science Centre, Baltimore's Maryland Science Center, Oklahoma City's Science Museum Oklahoma, San Francisco's Exploratorium, the Science Museum of Minnesota, the Museum of Science and Industry in Chicago, Pacific Science Center in Seattle, Jodrell Bank Observatory, St. Louis Science Center, Parkes Observatory in Australia and on the north campus lawn of North Carolina State University. A pair of dishes, typically in diameter, is installed facing each other, separated by around a hundred metres. A person standing at the focus of one can hear another person speaking in a whisper at the focus of the other, despite the wide separation between them. Parabolic microphones depend on a parabolic dish to reflect sound coming from a specific direction into the microphone placed at the focus. They are extremely directional: sensitive to sounds coming from a specific direction. However, they generally have poor bass response because a dish small enough to be portable cannot focus long wavelengths (= low frequencies). Small portable parabolic microphones are used to record wildlife sounds such as bird song, in televised sports events to pick up the conversations of players, such as in the huddle during American Football games, or to record the sounds of the sport, and in audio surveillance to record speech without the knowledge of the speaker. Locations Acoustic aircraft detection mirrors are known to have been built at: Denge, Kent Abbot's Cliff, Kent (at OS grid reference TR27083867) Boulby, Yorkshire Dover, Kent, at Fan Bay (OS grid reference TR352428) Hartlepool, County Durham, in the Clavering area Hythe, Kent Malta – five sound mirrors were planned for Malta, serialled alphabetically, but only the Magħtab wall is known to have been built: A. Magħtab (colloquially Il Widna - The Ear) B. Zonkor C. Ta Karach D. Ta Zura E. Tal Merhla Joss Gap, Kent Kilnsea, Yorkshire Leros,