Mariner's Compass

The mariner’s compass is the magnetized needle device that gave seafarers a reliable heading independent of sun and stars, introduced to European navigation in the late twelfth century after earlier use in China. Mounting the needle on a card marked with the wind rose, and later gimballing the bowl, made it usable in a seaway, and dry-card compasses gave way to liquid-filled bowls in the nineteenth century. The compass underpinned dead reckoning and chart navigation and is one of the essential instruments of the Age of Sail.