noun

• A small explosive charge which can be placed on a railway line in fog to be set off by the train as a signal to the driver.

  ‘Students were taught how to lay dummy charges and fog signals, then walk away and hide.’

  More example sentences

  • ‘Beavertail has probably seen more types of fog signals than any other New England lighthouse station.’
  • ‘The air fog signal was replaced by an electric omnidirectional signal controlled by a fog detector.’
  • ‘Construction began on the fog signal on July 1, 1890, and was completed on October 9 the same year.’
  • ‘Two years later, the original fog signal was replaced by a one and a half story, wood-framed structure.’
  • ‘In the 1820s a bell fog signal was apparently introduced at West Quoddy Head Lighthouse in Maine.’
  • ‘In the background is one of the two new electronic fog signals currently in use at Spring Point.’
  • ‘The original fog signal was a steam whistle, similar to the kind used in locomotives and ships.’
  • ‘The fog signal, a 12-inch steam whistle, was attached to the roof of the fog signal building.’
  • ‘There was a special felt lined cupboard for storing the detonators for the fog signal charges.’
  • ‘When the automated fog signal was installed the south window was blocked with the fog sensor.’
  • ‘These vessels, while constrained, are required to sound the same fog signal that would be sounded while underway.’
  • ‘The light has a nominal range of 22 miles and the fog signal a usual range of 2 miles.’
  • ‘Later various different fog signals were used until 1904 when a compressed air system replaced the old steam-operated signals.’
  • ‘Semaphore flags and fog signals are methods of communication.’