This page is about the navigational aid called foghorn, for the Ray Bradbury science fiction novel, see The fog horn
Foghorns are a navigation aid for mariners. In foggy conditions, when visual navigation aids such as lighthouses are obscured by the weather, fog horns provide an audible warning of rocks, headlands, or other dangers to shipping. The first automated steam-powered fog horn was invented by Robert Foulis of Saint John, New Brunswick, Canada. The first model was installed on Partridge Island in 1859, replacing the less effective bell and cannon which had been formerly used as warnings to ships in fog.
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