Definitions for backstaff
This page provides all possible meanings and translations of the word backstaff
An early navigational instrument for measuring the altitude of the sun and hence calculating latitude
an instrument formerly used for taking the altitude of the heavenly bodies, but now superseded by the quadrant and sextant; -- so called because the observer turned his back to the body observed
The backstaff is a navigational instrument that was used to measure the altitude of a celestial body, in particular the sun or moon. When observing the sun, users kept the sun to their back and observed the shadow cast by the upper vane on a horizon vane. It was invented by the English navigator John Davis that described it in his book Seaman's Secrets in 1594.
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