Definition of fog signal in English:
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.
- 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.