Hollow truncated cone filament
No English Term
A filament (usually of multi-vee formation) in the form of a hollow truncated cone, generated around the axis of the lamp.
Note: The filament may be fully closed in plan, or may embrace an arc of less than 360 degrees.
In the latter case, the French term is Grille Tronconique Incomplete or Filament Tronconique Incomplet and the English term is"Bunch filament" (2-3-220).
Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)
Number of cells
International Association of Marine Aids to Navigation and Lighthouse Authorities - AISM