Cross-Staff: Historical Navigational Tool for Measuring Celestial Angles #3477530 (License: Personal Use)

The cross-staff is a historical navigational instrument consisting of a long main staff with a movable transom (crosspiece) that slides along it. By aligning the transom with celestial objects like the sun or stars and the horizon, sailors could estimate angular height and thus their latitude. Its design evolved over time, with variants such as the backstaff improving accuracy and usability.

This image is typically used in educational or museum contexts-on history of navigation, maritime technology, or astronomy webpages-to illustrate pre-telescope celestial measurement tools. It serves users seeking historical understanding or visual reference for academic or hobbyist research.