Alternative terms: Electromagnetic horn (G.B.), (Electromagnetic air) Oscillator (U.S.A.)
A fog signal apparatus comprising a resonant diaphragm maintained in vibrating motion by electromagnetic action.
Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)
centre of gravity
Centre of buoyancy
International Association of Marine Aids to Navigation and Lighthouse Authorities - AISM