Diaphone - Cylinder
Cylinder (of a diaphone)
The fixed part of the modulator in which one part of the double piston slides; the modulation of the air is obtained by action of the slots on the two parts of the modulator moving in and out of concidence.
Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)
International Association of Marine Aids to Navigation and Lighthouse Authorities - AISM