Galle Fort Dutch rampart signal station: semaphore flag communications with harbor ships?

Before wireless radio communications, Galle Harbour managed maritime traffic via an optical semaphore station atop the historic Flag Rock and Dutch ramparts. Signalmen hoisted standardized Marryat code flags to guide incoming sailing vessels past outer coral reefs into safe harbor anchorages. In the late 19th century, a precision Time Ball apparatus operated near the lighthouse: a large canvas-covered sphere was hoisted to the top of a mast and dropped mechanically at exactly 1:00 PM local time via telegraphic pulse from the Colombo Observatory. Ship captains observed the drop through telescopes to synchronize marine chronometers for navigation calculations.