On 22 October 1854 the New Brunswick Morning News described a new life-saving invention: the steam whistle fog alarm. A chain of lighthouses was safeguarding shipping off the Canadian coast but in foggy conditions their lights were invisible. Fog bells could not be heard at long distances, and cannon signals were expensive and labour intensive.
The steam whistle was invented by Robert Foulis, a Scot who studied engineering but worked as a portrait painter. Foulis had been walking home on a foggy night and heard his daughter playing the piano. He noticed how fog muffled the high notes but the low notes carried clearly.
This inspired him to build a whistle, powered by superheated steam, which could produce an exceptionally low note. It made a highly effective fog alarm. A clockwork valve sounded the whistle automatically at regular intervals; alternatively it could be operated manually to send signals in Morse code.
The steam whistle fog alarm was a great success, and ship owners lobbied British lighthouse authorities to install similar warning signals. Trinity House evaluated and compared various whistles, trumpets, sirens and other devices.
They eventually settled on a foghorn, which was first installed at St Abb’s Head lighthouse in Scotland during 1876. This original foghorn was succeeded by the diaphone horn, based on a church organ stop and powered by compressed air. The diaphone is named for its distinctive two-tone call, low then lower still, which became a familiar sound around the British coastline in foggy weather.
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