Cross-Staff

The cross-staff, like the astrolabe, was used to measure the altitude of the sun or a star above the horizon. At the pinnacle of its development it consisted of a graduated staff with a set of interchangeable vanes that enabled the navigator to measure angles between 10º and 90º. While the cross-staff was an improvement over earlier navigational instruments, it had a few shortcomings of its own; the most problematic being that the navigator had to look directly into the sun to take a reading.

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