An instrument formerly used for taking the altitude of the heavenly bodies, but now superseded by the quadrant and sextant; -- so called because the observer turned his back to the body observed.
Use in sentences of BACKSTAFF
Meaning of BACKSTAFF in English
An instrument formerly used for taking the altitude of the heavenly bodies, but now superseded by the quadrant and sextant; -- so called because the observer turned his back to the body observed.