A foghorn is a device that produces a loud, deep sound to warn ships and boats of navigational hazards such as rocky coastlines or other vessels in foggy or poor visibility conditions. It is most commonly used in marine transport to provide an audible warning when visual aids like lighthouses are obscured by fog. The foghorn sound is usually a low-frequency tone that travels long distances through fog. The invention of the automated steam-powered foghorn is attributed to Robert Foulis, a Canadian inventor, in 1859. Foghorns remain an important navigational tool, although modern technology like GPS has reduced their use in some areas.
