411 REFERENCE · Wiktionary
Ardois system
Reference material by Wiktionary contributors. This retains its source identity and is not 411 news reporting.
English
Ardois Light System
Etymology
en
Proper noun
1
en historical A system used by the US Navy in the late 19th century to enable ship-to-ship communications at night. Each installation used a series of eight double lamps (four red and four white) hung from a mast and used to transmit visual codes.