Researched
Sextant
John Hadley's reflecting octant (1731), later the sextant, measures the Sun's height above the horizon from a pitching ship.
Open in the interactive tree →Mirrors let a navigator see the horizon and the Sun together and read the angle precisely. With a chronometer it gave sailors latitude and longitude at sea.
Prerequisites
Unlocks
- Marine Chronometer1761Longitude comes from comparing sextant sights with chronometer time
Sources
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