Noun: heliograph 'hee-lee-u,grãf
- An apparatus for sending telegraphic messages by using a mirror to turn the sun's rays off and on
"Soldiers used a heliograph to communicate across long distances in the desert"
- Signal by means of a mirror and the using the sun's rays
"The stranded hikers heliographed their location to the rescue team"
Derived forms: heliographs, heliographing, heliographed
Type of: apparatus, setup, sign, signal, signalise [Brit], signalize
Encyclopedia: Heliograph