Cross-Staff Navigational Instrument

Timeline

1. c. 1480–1510Portuguese navigation school · PortugalPortuguese navigators adapted the astronomer's Jacob's staff into an onboard latitude-measuring tool, sighting Polaris or the noon sun to read altitude and compute latitude, enabling precise navigation in the Atlantic and Indian Ocean and supporting the eastward route around Africa.
2. 1520–1594Major European ports · Atlantic coastBy the mid-16th century, the cross-staff had become standard navigational equipment on Spanish, Portuguese, Dutch, and English ocean-going fleets and was recorded in official sailing manuals. Its main drawback was the need to stare directly at the sun, causing large observational errors and spurring development of more precise instruments.
3. 1601–1610Transoceanic routes of the Atlantic and Pacific · Pacific OceanBetween 1601 and 1610, although the back-staff had been invented in 1594, the cross-staff was still widely carried on Manila galleon routes, Dutch East India Company fleets, and the English East India Company's first expedition, owing to its low cost and ease of use.
4. 1620–1660European navigation schools and fleets · EuropeIn the mid-17th century, the spread of the more accurate back-staff and quadrant gradually removed the cross-staff from mainstream ocean navigation; after Hadley's octant appeared in 1731, the cross-staff became purely a historical artifact.