heliograph Meaning, Definition & Usage

  1. noun an apparatus for sending telegraphic messages by using a mirror to turn the sun's rays off and on
  2. verb signal by means of a mirror and the using the sun's rays

WordNet

He"li*o*graph noun
Etymology
Helio- + -graph.
Definitions
  1. A picture taken by heliography; a photograph.
  2. An instrument for taking photographs of the sun.
  3. An apparatus for telegraphing by means of the sun's rays. See Heliotrope, 3.

Webster 1913