A visible time signalSourced
Ships set their clocks when a raised ball began to fall
Nineteenth-century ports used time balls: raised balls dropped at a predetermined time so navigators could synchronize marine chronometers. The reference moment was the start of the descent, not arrival at the bottom. A large moving object made precise time visible at a distance.
The fall was a signal, not just a spectacle.
Summary / translation: Unbubly · CC BY-SA 4.0
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Time ball · Wikimedia contributors
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Reviewed: 2026-10-05