Historical detoursSourced
Messages travelled
without wires.
Optical telegraphs relayed coded positions of arms or other signals from tower to tower over long distances.
A clear line of sight
served as the connection.
Summary / translation: Unbubly · CC BY-SA 4.0
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Optical telegraph · Wikimedia contributors
Adapted, summarized and translated from the source. Adapted text is also available under CC BY-SA 4.0.
Reviewed: 2026-09-30