Le criard / Fog horn

At Cap-des-Rosiers lighthouse, fog remained a major danger to navigation even though the light was one of the colony's most powerful beams, because in fog no coastal landmarks could be seen day or night. To help navigators determine their exact position and stay on course, the light was supplemented by a local sound signal. The first fog signal, introduced in 1858, was a fog cannon fired with blanks every hour, and every half-hour starting in 1881, using about 3000 pounds of gunpowder each year. Because so much highly flammable powder was required, a powder magazine was built away from the house and service buildings to protect the keeper, his assistants, and his family. In 1882, the cannon was replaced by an alarm whistle operating on the same principle as old locomotive whistles; it sounded once a minute, cost less, carried farther, and was much safer. In 1906, a steam-powered compressed-air diaphone replaced the whistle and proved much more efficient. In 1972, authorities replaced the diaphone with a fully automatic electronic device with a fog detector and horns that was more reliable and required far less maintenance than a system needing constant human presence. Today, no fog signal is used at the lighthouse because of technological advances and the adoption of satellite navigation aids.

Quebec · Canada