What is an instrument for making signals to an observer at a distance, by means of the sun's rays thrown from a mirror called?
heliotrope — (Geodesy & Signal Service) An instrument for making signals to an observer at a distance, by means of the sun's rays thrown from a mirror. (Webster's 1913.)
Sources
- Webster's Unabridged Dictionary, 1913 edition (public domain, via GCIDE / Project Gutenberg).
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- Published: 2026-07-17T00:00:00-07:00 · Modified: 2026-07-17T00:00:00-07:00